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  • 51.
    Larsson, Fredrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Keller, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Törndahl, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Atomic layer deposition of amorphous tin-gallium oxide films2019Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, nr 3, artikel-id 030906Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A wide range of applications benefit from transparent semiconducting oxides with tunable electronic properties, for example, electron transport layers in solar cell devices, where the electron affinity is a key parameter. Presently, a few different ternary oxides are used for this purpose, but the attainable electron affinity range is typically limited. In this study, the authors develop a low-temperature atomic layer deposition (ALD) process to grow amorphous Sn1-xGaxOy thin films from dimethylamino-metal complexes and water. This oxide is predicted to provide a wide selection of possible electron affinity values, from around 3 eV for pure Ga2O3 to 4.5 eV for pure SnO2. The ALD process is evaluated for deposition temperatures in the range of 105-195 degrees C by in situ quartz crystal microbalance and with ex situ film characterization. The growth exhibits an ideal-like behavior at 175 degrees C, where the film composition can be predicted by a simple rule of mixture. Depending on film composition, the growth per cycle varies in the range of 0.6-0.8 angstrom at this temperature. Furthermore, the film composition for a given process appears insensitive to the deposition temperature. From material characterization, it is shown that the deposited films are highly resistive, fully amorphous, and homogeneous, with moderate levels of impurities (carbon, nitrogen, and hydrogen). By tailoring the metal cation ratio in films grown at 175 degrees C, the optical bandgap can be varied in the range from 2.7 eV for SnO2 to above 4.2 eV for Ga2O3. The bandgap also varies significantly as a function of deposition temperature. This control of properties indicates that Sn1-xGaxOy is a promising candidate for an electron transport layer material in a wide electron affinity range. Published by the AVS.

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  • 52.
    Ledinek, Dorothea
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    In the confines of Cu(In,Ga)Se2 thin film solar cells with rear surface passivating oxide layers2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The material supply to build renewable energy conversion systems needs to be considered from both a cost and an energy security perspective. For Cu(In,Ga)Se2 (CIGS) thin film solar cells the use of indium in the absorber layer is most problematic. The material input per service unit can be reduced, if the absorber layers are thinned down without a loss in power conversion efficiency.

    Thinning down absorber layers can increase the conversion efficiency. However, for real CIGS solar cells absorption losses and recombination rates at the rear surface between the CIGS absorber and the Mo rear contact as well as shunt-like behavior increase. Thus, both rear surface passivation and optical management are essential for maintaining high power conversion efficiencies.

    In this work, thin oxide layers, so-called passivation layers, are introduced between the CIGS absorber layer and the Mo contact. They can passivate the CIGS surface, if the CIGS-oxide interface has a lower defect density than the CIGS-Mo interface and/or if they contain a negative fixed oxide charge, which increases the hole concentration and reduces the electron concentration in the CIGS in the vicinity of the oxide.

    As these oxides are insulators, electrical conduction through the passivation layer has to be ensured. In this work, nanopoint contacts were etched into ALD-Al2O3 passivation layers in CIGS solar cells. These solar cells had 0.5 -1.5 µm thin absorber layers with a low In content and a high band gap. Ga grading was not used. Although absorber layers with a high Ga content have a short minority carrier diffusion length, a passivation effect could be discerned with the help of external quantum efficiency measurements and current-voltage measurements under varying temperatures in combination with optical and electrical modeling with a two-diode model. Moreover, the possibility of leaving out the additional fabrication step has been explored for ALD-Al2O3 and HfO2 as passivation layers. The results suggest that the passivation layer does not necessarily need to be opened for electrical conduction in an additional fabrication step, if sodium fluoride (NaF) is deposited onto Al2O3 layers prior to CIGS evaporation. In this case solar cells with 215 nm absorber layers and 6 nm thin passivation layers have a power conversion efficiency of 8.6 %, which is 3 % (absolute) higher than the conversion efficiency on a reference. Shunt-like behavior is additionally reduced. For the HfO2 layers photoluminescence data indicate a good passivation effect, but the layers need to be opened up to ensure conduction.

    Delarbeten
    1. Thickness and Ga content variations in co-evaporated CIGS solar cells with a flat Ga profile: an electrical characteriyation
    Öppna denna publikation i ny flik eller fönster >>Thickness and Ga content variations in co-evaporated CIGS solar cells with a flat Ga profile: an electrical characteriyation
    2014 (Engelska)Ingår i: EU PVSEC 2014 Proceedings Papers, Munchen, 2014, s. 1832-1836Konferensbidrag, Publicerat paper (Övrigt vetenskapligt)
    Abstract [en]

    In this work an extensive experimental series has been carried out by co-evaporating CIGS layers with varying thickness (0.5, 1.0, 1.5 µm) and varying Ga content (Ga/(Ga+In)=0.15, 0.30, 0.45 and 0.60). In all CIGS layers the Cu concentration has been held constant at Cu/(In+Ga)=0.85. The cells have been characterized with dark and light current voltage measurements, external quantum efficiency measurements and apparent quantum efficiency measurements at negative bias. In agreement with the literature, we observe a distinctively shorter collection length for high Ga concentrations and voltage dependent photo current collection for all cells. Voltage dependent current collection however cannot alone explain our data and the cells need to be described with an illumination dependent diode current or photo current. The generation dependent diode or photo current increase the slope of the light JV curve at negative bias voltage for all solar cells and dominates the slope in cells with 0.5 µm thin absorbers regardless of Ga content. We propose that this behavior is connected to the recombination at the back contact, as it is smaller in the cells with thick absorber layers and since we do not observe the same behavior in back side passivated cells. Keywords: Cu(InGa)Se2, Modelling, Electrical Characterization, Shunting, Ga content, thin absorbers, superposition principle, shifting approximation

    Ort, förlag, år, upplaga, sidor
    Munchen: , 2014
    Nyckelord
    CIGS; CIGSe; Thin film solar cells; GGI; Ga content; electrical characterization;
    Nationell ämneskategori
    Den kondenserade materiens fysik
    Forskningsämne
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-390309 (URN)
    Konferens
    29th European Photovoltaic Solar Energy Conference and Exhibition,22-26 September, 2014, Amsterdam
    Tillgänglig från: 2019-08-08 Skapad: 2019-08-08 Senast uppdaterad: 2019-08-29Bibliografiskt granskad
    2. Rear Contact Passivation for High Bandgap Cu(In,Ga)Se2 Solar Cells With a Flat Ga profile
    Öppna denna publikation i ny flik eller fönster >>Rear Contact Passivation for High Bandgap Cu(In,Ga)Se2 Solar Cells With a Flat Ga profile
    Visa övriga...
    2018 (Engelska)Ingår i: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 8, nr 3, s. 864-870Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this study, Cu(In, Ga)Se2 solar cells with a high bandgap (1.31 eV) and a flat Ga profile ([Ga]/([Ga]+[In]) ≈ 0.60) were examined. For absorber layer thicknesses varying from 0.60 to 1.45 μm, the Mo rear contact of one set of samples was passivated with an ultrathin (27 nm) Al2O3 layer with point contact openings, and compared with reference samples where the rear contact remained unpassivated. For the passivated samples, mainly large gains in the short-circuit current led to an up to 21% (relative) higher power conversion efficiency compared with unpassivated cells. The differences in temperature-dependent current voltage behavior between the passivated and the unpassivated samples and the thin and the thick samples can be explained by an oppositely poled secondary photodiode at the rear contact.

    Nyckelord
    Back contact, CIGS, CIGSe, Cu(In, Ga)Se-2, energy barrier, passivation, rear contact, thin films, two-diode model
    Nationell ämneskategori
    Den kondenserade materiens fysik Teknik och teknologier
    Identifikatorer
    urn:nbn:se:uu:diva-356073 (URN)10.1109/JPHOTOV.2018.2813259 (DOI)000430718700029 ()
    Forskningsfinansiär
    EnergimyndighetenStandUp
    Tillgänglig från: 2018-07-13 Skapad: 2018-07-13 Senast uppdaterad: 2019-08-08
    3. Effect of different Na supply methods on thin Cu(In,Ga)Se2 solar cells with Al2O3 rear passivation layers
    Öppna denna publikation i ny flik eller fönster >>Effect of different Na supply methods on thin Cu(In,Ga)Se2 solar cells with Al2O3 rear passivation layers
    Visa övriga...
    2018 (Engelska)Ingår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 187, nr 1, s. 160-169Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this work, rear-contact passivated Cu(In,Ga)Se2 (CIGS) solar cells were fabricated without any intentional contact openings between the CIGS and Mo layers. The investigated samples were either Na free or one of two Na supply methods was used, i) a NaF precursor on top of the Al2O3 rear passivation layer or ii) an in situ post- deposition treatment with NaF after co-evaporation of the CIGS layer. The thickness of the ALD-Al2O3 passi- vation layer was also varied in order to find an optimal combination of Na supply and passivation layer thickness. Our results from electrical characterization show remarkably different solar cell behavior for different Na supplies. For up to 1nm thick Al2O3 layers an electronically good contact could be confirmed independently of Na deposition method and content. When the Al2O3 thickness exceeded 1 nm, the current was blocked on all samples except on the samples with the NaF precursor. On these samples the current was not blocked up to an Al2O3 layer thickness of about 6 nm, the maximum thickness we could achieve without the CIGS peeling off the Al2O3 layer. Transmission electron microscopy reveals a porous passivation layer for the samples with a NaF precursor. An analysis of the dependence of the open circuit voltage on temperature (JVT) indicates that a thicker NaF precursor layer lowers the height of the hole barrier at the rear contact for the passivated cells. This energy barrier is also lower for the passivated sample, compared to an unpassivated sample, when both samples have been post-deposition treated.

    Nyckelord
    Alkali, Back contact, CIGS, Passivation, Thin films, Rear contact, Tunneling
    Nationell ämneskategori
    Elektroteknik och elektronik Energisystem Annan materialteknik
    Identifikatorer
    urn:nbn:se:uu:diva-357123 (URN)10.1016/j.solmat.2018.07.017 (DOI)000445308300019 ()
    Forskningsfinansiär
    Vetenskapsrådet, 43523-1StandUpEU, Horisont 2020, 720887
    Tillgänglig från: 2018-08-12 Skapad: 2018-08-12 Senast uppdaterad: 2019-08-08Bibliografiskt granskad
    4. Effect of NaF pre-cursor on alumina and hafnia rear contact passivation layers in ultra-thin Cu(In,Ga)Se2 solar cells
    Öppna denna publikation i ny flik eller fönster >>Effect of NaF pre-cursor on alumina and hafnia rear contact passivation layers in ultra-thin Cu(In,Ga)Se2 solar cells
    Visa övriga...
    2019 (Engelska)Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 683, s. 156-164Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this work, we evaluate the effect of NaF layers on the properties of Al2O3 and HfO2 rear contact passivation layers in ultra-thin Cu(In,Ga)Se2 solar cells. The 6 nm thin passivation layers were deposited by atomic layer deposition and neither intentionally opened nor nano-patterned in any extra-fabrication step. NaF layers, 7.5 or 15 nm thin, were deposited as precursors prior to CIGS absorber co-evaporation. The 215 nm thick absorbers were co-evaporated with constant evaporation rates for all elements. Directly thereafter, a 70 nm thick cadmium sulfide layer was deposited. Photoluminescence measurements indicate a strongly reduced recombination at the rear contact for all passivated samples compared to an unpassivated reference. Although the sample with Al2O3 passivation and a 15 nm NaF precursor layer luminesces by far the least of the passivated samples, solar cells made from this sample show the highest efficiency (8.6% compared with 5.6% for the reference with no passivation). The current-voltage curves of the solar cells fabricated from the sample with 7.5 nm NaF on top of the Al2O3 layer and both samples with HfO2 exhibit blocking behavior to various degrees, but a high photoluminescence response. We conclude that NaF precursor layers increase conduction through the Al2O3 layer, but also reduce its effectiveness as a passivation layer. In contrast, conduction through the HfO2 passivation layers seem to not be influenced by NaF precursor layers, and thus requires nano-patterning or thinning for conduction.

    Ort, förlag, år, upplaga, sidor
    ELSEVIER SCIENCE SA, 2019
    Nyckelord
    Alkali, Alumina, Copper indium gallium diselenide, Hafnia, Passivation, Sodium fluoride, Ultra-thin
    Nationell ämneskategori
    Den kondenserade materiens fysik Teknik och teknologier
    Identifikatorer
    urn:nbn:se:uu:diva-387716 (URN)10.1016/j.tsf.2019.05.024 (DOI)000469854700020 ()
    Forskningsfinansiär
    EnergimyndighetenVetenskapsrådet, 621-2014-5599StandUp
    Tillgänglig från: 2019-06-26 Skapad: 2019-06-26 Senast uppdaterad: 2020-02-05Bibliografiskt granskad
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  • 53.
    Axelsson, Mathias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Transparent conductive oxides deposited by magnetron sputtering: synthesis and characterization2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The thesis has dealt with transparent conducting oxide (TCO) materials, with a focus on Al:ZnO and with studies on Sn:In2O3 and ZnO. TCOs are a material group that is used for its properties of being conductive and at the same time transparent. In solar cells, a top layer of TCO is often used to allow light to transmit into the cell and then conduct the resulting current.

     

    A set of growth parameters was chosen and optimized through a literature study and experiments. The depositied thin films were characterized by optical and electrical characterization methods. Rf-magnetron-sputtering was used as the deposition method, where the influence of O2, argon and substrate temperature were the parameters to be studied. As a part of the characterization a model for spectroscopic ellipsometry on Al:ZnO was made, enabling faster measurement of transport properties. The main parameter affecting the TCO properties was found to be oxygen flow and the optimum flow value for each material has been determined. Substrate heating did not show any significant improvement on the resistivity of Al:ZnO with a minimum value of ~5.0*10-4 Ωcm while no heating resulted in a value of ~6.0*10-4  Ωcm. These values are comparable to the state-of-the-art from the literature.

     

    As a demonstration of application, the developed AZO and ZnO were applied to CIGS solar cells and these were compared to a reference. The newly developed AZO and ZnO was comparable to the reference but a lower mean fill factor indicates that improvements can be made.

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  • 54.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    A novel gate junction design for low noise Si Nanowire ISFET Sensor application2019Konferensbidrag (Övrigt vetenskapligt)
  • 55.
    Malmquist, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Prototype manufacturing of microwave components using plastic 3D printing2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The ability to easily customize and produce specialized MW-components for research and industry is a real challenge and the need is identified, as standardized parts have limited use and can limit design freedom. This study aims at exploring if there are simple ways to manufacture rectangular X-band waveguides with operating frequency of 8-12GHz with novel polymer additive manufacturing and chemical metal deposition that can match Computer Numerical Control (CNC) manufactured rectangular metal waveguides in performance. X-band was chosen mostly because of it having a good size to start printing trials and x-band components being in heavy use where a lightweight would be beneficial. Also, to evaluate the manufacturing results by measuring and comparing s-parameters and weight between measuring standard and manufactured waveguides. Furthermore, to use the preexisting models for approximating the attenuation due to surface roughness. Different designs were tested with different polymers and electrodeposition techniques and approaches. Two of the benchmarked techniques gave better results; first, using a modular design with a combination of different polymers and an industrial copper plating technique; second, a single polymer one-piece design using an acrylic carbon paint and a small scale in-house electroless copper deposition. The performance of conventionally manufactured rectangular metal waveguides was not matched but the two investigated techniques show on results that the techniques could possibly be modified in the future to match the performance of conventionally manufactured waveguides.

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  • 56.
    Andreasson, Joel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Design och konstruktion av distorsionseffekt för gitarrer2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This project has been done as a part of a bachelors degree in engineering at Uppsala university. The project was supervised by Jörgen Olsson at the division of solid state electronics.

    The goal of this project was to develop a distortion effect that can be used with an guitar and a amplifier. The effect was to have controllable distorsion, volume and tone control including bass and treble. The circuit is also supposed to be run using a 9V battery as power supply, which means that the in circuit currents shold be low. When the circuit was finished it was also analyzed through different measurements and simulations.

    The distortion of the circuit was achieved using diodes to get a nonlinear amplification. The goals of the circuit controls was achieved, and although a low circuit current was achieved, it only satisfied the goal of 1 mA when high distorsion was set for the circuit.

    When measuring and simulating the system, some major differences was found. The simulated frequency response characteristics was found to be very different from the measured. This is likely due to the simulation program not being

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  • 57.
    Mastrothanasis, Helene Alexandra
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Antonsson, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Sahlin, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Kamerahus med inbyggd autofokus2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Autofokus i en kamera fungerar genom att elektroniskt ändra avståndetmellan lins och sensor, och låta en dator avgöra när motivet är ifokus. I detta projekt testades en metod där fokus fås med hjälp aven flyttbar sensor inuti kamerahuset. Kamerahuset byggdes med hjälpav 3D-printning, och elektroniken styrdes med en Raspberry Pi. Vidareanvändes en metod där linsen projicerar på en yta som sedanfotograferas av, istället för direkt på en fotosensor. Resultat varen fungerande kamera, men med bristfällig bildkvalitét. Utifrånresultatet kan slutsatsen dras att metoden även skulle fungera ikommersiellt syfte.

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  • 58.
    Ledinek, Dorothea
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Keller, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Hägglund, Carl
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Chen, Wei-Chao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Effect of NaF pre-cursor on alumina and hafnia rear contact passivation layers in ultra-thin Cu(In,Ga)Se2 solar cells2019Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 683, s. 156-164Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we evaluate the effect of NaF layers on the properties of Al2O3 and HfO2 rear contact passivation layers in ultra-thin Cu(In,Ga)Se2 solar cells. The 6 nm thin passivation layers were deposited by atomic layer deposition and neither intentionally opened nor nano-patterned in any extra-fabrication step. NaF layers, 7.5 or 15 nm thin, were deposited as precursors prior to CIGS absorber co-evaporation. The 215 nm thick absorbers were co-evaporated with constant evaporation rates for all elements. Directly thereafter, a 70 nm thick cadmium sulfide layer was deposited. Photoluminescence measurements indicate a strongly reduced recombination at the rear contact for all passivated samples compared to an unpassivated reference. Although the sample with Al2O3 passivation and a 15 nm NaF precursor layer luminesces by far the least of the passivated samples, solar cells made from this sample show the highest efficiency (8.6% compared with 5.6% for the reference with no passivation). The current-voltage curves of the solar cells fabricated from the sample with 7.5 nm NaF on top of the Al2O3 layer and both samples with HfO2 exhibit blocking behavior to various degrees, but a high photoluminescence response. We conclude that NaF precursor layers increase conduction through the Al2O3 layer, but also reduce its effectiveness as a passivation layer. In contrast, conduction through the HfO2 passivation layers seem to not be influenced by NaF precursor layers, and thus requires nano-patterning or thinning for conduction.

  • 59.
    Cavallaro, Sara
    et al.
    KTH Royal Inst Technol, Sch Engn Sci, Dept Appl Phys, S-16440 Kista, Sweden.
    Horak, Josef
    KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Prot Sci, AlbalNova Univ Ctr, S-10691 Stockholm, Sweden.
    Haag, Petra
    Karolinska Inst, Karolinska Univ Hosp, Dept Oncol Pathol, Theme Canc,Patient Area,Pelvis, Akad Straket 1, S-17164 Stockholm, Sweden.
    Gupta, Dhanu
    Karolinska Inst, Clin Res Ctr, Dept Lab Med, S-17177 Stockholm, Sweden;Evox Therapeut Ltd, Oxford OX4 4HG, England.
    Stiller, Christiane
    KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Prot Sci, AlbalNova Univ Ctr, S-10691 Stockholm, Sweden.
    Sahu, Siddharth S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Gorgens, Andre
    Karolinska Inst, Clin Res Ctr, Dept Lab Med, S-17177 Stockholm, Sweden;Evox Therapeut Ltd, Oxford OX4 4HG, England;Univ Duisburg Essen, Univ Hosp Essen, Inst Transfus Med, D-45122 Essen, Germany.
    Gatty, Hithesh Kumar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Viktorsson, Kristina
    Karolinska Inst, Dept Oncol Pathol, Karolinska Univ Hosp, Theme Canc,Patient Area,Head & Neck Lung & Skin, Akad Straket 1, S-17164 Solna, Sweden.
    El Andaloussi, Samir
    Karolinska Inst, Clin Res Ctr, Dept Lab Med, S-17177 Stockholm, Sweden;Evox Therapeut Ltd, Oxford OX4 4HG, England.
    Lewensohn, Rolf
    Karolinska Inst, Dept Oncol Pathol, Karolinska Univ Hosp, Theme Canc,Patient Area,Head & Neck Lung & Skin, Akad Straket 1, S-17164 Solna, Sweden.
    Karlstrom, Arnelie E.
    KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Prot Sci, AlbalNova Univ Ctr, S-10691 Stockholm, Sweden.
    Linnros, Jan
    KTH Royal Inst Technol, Sch Engn Sci, Dept Appl Phys, S-16440 Kista, Sweden.
    Dev, Apurba
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Label-Free Surface Protein Profiling of Extracellular Vesicles by an Electrokinetic Sensor2019Ingår i: ACS SENSORS, ISSN 2379-3694, Vol. 4, nr 5, s. 1399-1408Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Small extracellular vesicles (sEVs) generated from the endolysosomal system, often referred to as exosomes, have attracted interest as a suitable biomarker for cancer diagnostics, as they carry valuable biological information and reflect their cells of origin. Herein, we propose a simple and inexpensive electrical method for label-free detection and profiling of sEVs in the size range of exosomes. The detection method is based on the electrokinetic principle, where the change in the streaming current is monitored as the surface markers of the sEVs interact with the affinity reagents immobilized on the inner surface of a silica microcapillary. As a proof-of-concept, we detected sEVs derived from the non-small-cell lung cancer (NSCLC) cell line H1975 for a set of representative surface markers, such as epidermal growth factor receptor (EGFR), CD9, and CD63. The detection sensitivity was estimated to be similar to 175000 sEVs, which represents a sensor surface coverage of only 0.04%. We further validated the ability of the sensor to measure the expression level of a membrane protein by using sEVs displaying artificially altered expressions of EGFR and CD63, which were derived from NSCLC and human embryonic kidney (HEK) 293T cells, respectively. The analysis revealed that the changes in EGFR and CD63 expressions in sEVs can be detected with a sensitivity in the order of 10% and 3%, respectively, of their parental cell expressions. The method can be easily parallelized and combined with existing microfluidic-based EV isolation technologies, allowing for rapid detection and monitoring of sEVs for cancer diagnosis.

  • 60.
    Fjellstedt, Christoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Methods for including stiffness parameters from reduced finite element models in simulations of multibody systems2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Two methods using lumped element (lumped parameter) methods to model flexible bodies have been presented. The methods are based on the concept of using a Guyan reduced stiffness matrix to describe the elasticity of a body. The component to be modeled has been divided into two parts using FE software and the mass and inertia tensor for the respective part of the component have been retrieved. The first method has been based on including the elements from the stiffness matrix in compliant constraints. The compliant constraints have been derived and a prototype has been implemented in MATLAB. It has been shown that using compliant constraints and stiffness parameters from a Guyan reduced stiffness matrix it is possible, with highly accurate results, to describe the deformation of a flexible body in multibody simulations.

    The second method is based on springs and dampers and has been implemented in the simulation environment Dymola. The springs and dampers have been constructed to include coupling elements from a Guyan reduced stiffness matrix. It has been shown that using the proposed method it is possible, with highly accurate results, to describe the static deformation of a flexible body. Further, using dynamic simulations of a full robot manipulator model, it has been shown that it is possible to use the spring-damper model to capture the deformation of the links of a manipulator in dynamic simulations with large translations and rotations.

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  • 61.
    Wen, Chenyu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Solid-State Nanopores for Sensing: From Theory to Applications2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Nanopore based sensing technology has been widely studied for a broad range of applications including DNA sequencing, protein profiling, metabolite molecules, and ions detection. The nanopore technology offers an unprecedented technological solution to meeting the demands of precision medicine on rapid, in-field, and low-cost biomolecule analysis. In general, nanopores are categorized in two families: solid-state nanopore (SSNP) and biological nanopore. The former is formed in a solid-state membrane made of SiNx, SiO2, silicon, graphene, MoS2, etc., while the latter represents natural protein ion-channels in cell membranes. Compared to biological pores, SSNPs are mechanically robust and their fabrication is compatible with traditional semiconductor processes, which may pave the way to their large-scale fabrication and high-density integration with standard control electronics. However, challenges remain for SSNPs, including poor stability, low repeatability, and relatively high background noise level. This thesis explores SSNPs from basic physical mechanisms to versatile applications, by entailing a balance between theory and experiment.

    The thesis starts with theoretical models of nanopores. First, resistance of the open pore state is studied based on the distribution of electric field. An important concept, effective transport length, is introduced to quantify the extent of the high field region. Based on this conductance model, the nanopores size of various geometrical shapes can be extracted from a simple resistance measurement. Second, the physical causality of ionic current rectification of geometrically asymmetrical nanopores is unveiled. Third, the origin of low-frequency noise is identified. The contribution of each noise component at different conditions is compared. Forth, a simple nano-disk model is used to describe the blockage of ionic current caused by DNA translocation. The signal and noise properties are analyzed at system level.

    Then, nanopore sensing experiments are implemented on cylinder SiNx nanopores and truncated-pyramid silicon nanopores (TPP). Prior to a systematic study, a low noise electrical characterization platform for nanopore devices is established. Signal acquisition guidelines and data processing flow are standardized. The effects of electroosmotic vortex in TPP on protein translocation dynamics are excavated. The autogenic translocation of DNA and proteins driven by the pW-level power generated by an electrolyte concentration gradient is demonstrated. Furthermore, by extending to a multiple pore system, the group translocation behavior of nanoparticles is studied. Various application scenarios, different analyte categories and divergent device structures accompanying with flexible configurations clearly point to the tremendous potential of SSNPs as a versatile sensor.

    Delarbeten
    1. Physical Model for Rapid and Accurate Determination of Nanopore Size via Conductance Measurement
    Öppna denna publikation i ny flik eller fönster >>Physical Model for Rapid and Accurate Determination of Nanopore Size via Conductance Measurement
    2017 (Engelska)Ingår i: ACS SENSORS, ISSN 2379-3694, Vol. 2, nr 10, s. 1523-1530Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Nanopores have been explored for various biochemical and nanoparticle analyses, primarily via characterizing the ionic current through the pores. At present, however, size determination for solid-state nanopores is experimentally tedious and theoretically unaccountable. Here, we establish a physical model by introducing an effective transport length, L (eff) that measures, for a symmetric nanopore, twice the distance from the center of the nanopore where the electric field is the highest to the point along the nanopore axis where the electric field falls to e-(1)of this maximum. By G = sigma(s0)/L-eff, a simple expression S-0=/(G, sigma, h, beta) is derived to algebraically correlate minimum nanopore cross-section area S (0)to nanopore conductance G, electrolyte conductivity a, and membrane thickness h with (3 to denote pore shape that is determined by the pore fabrication technique. The model agrees excellently with experimental results for nanopores in graphene, single-layer MoS2, and ultrathin SiNx films. The generality of the model is verified by applying it to micrometer-size pores.

    Nyckelord
    nanopores, physical model, effective transport length, algebraic solution, conductance measurement in electrolyte
    Nationell ämneskategori
    Nanoteknik
    Identifikatorer
    urn:nbn:se:uu:diva-340952 (URN)10.1021/acssensors.7b00576 (DOI)000414238600021 ()28974095 (PubMedID)
    Forskningsfinansiär
    Vetenskapsrådet, 621-2014-6300
    Tillgänglig från: 2018-02-13 Skapad: 2018-02-13 Senast uppdaterad: 2019-06-19Bibliografiskt granskad
    2. Zero-Depth Interfacial Nanopore Capillaries
    Öppna denna publikation i ny flik eller fönster >>Zero-Depth Interfacial Nanopore Capillaries
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    2018 (Engelska)Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 30, nr 9, artikel-id 1703602Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    High-fidelity analysis of translocating biomolecules through nanopores demands shortening the nanocapillary length to a minimal value. Existing nanopores and capillaries, however, inherit a finite length from the parent membranes. Here, nanocapillaries of zero depth are formed by dissolving two superimposed and crossing metallic nanorods, molded in polymeric slabs. In an electrolyte, the interface shared by the crossing fluidic channels is mathematically of zero thickness and defines the narrowest constriction in the stream of ions through the nanopore device. This novel architecture provides the possibility to design nanopore fluidic channels, particularly with a robust 3D architecture maintaining the ultimate zero thickness geometry independently of the thickness of the fluidic channels. With orders of magnitude reduced biomolecule translocation speed, and lowered electronic and ionic noise compared to nanopores in 2D materials, the findings establish interfacial nanopores as a scalable platform for realizing nanofluidic systems, capable of single-molecule detection.

    Ort, förlag, år, upplaga, sidor
    WILEY-V C H VERLAG GMBH, 2018
    Nyckelord
    2D nanopores, biomolecules, 1, f noise, mechanical stability, translocation speed
    Nationell ämneskategori
    Den kondenserade materiens fysik Atom- och molekylfysik och optik Teknik och teknologier
    Identifikatorer
    urn:nbn:se:uu:diva-350489 (URN)10.1002/adma.201703602 (DOI)000426491600035 ()
    Forskningsfinansiär
    Vetenskapsrådet, 621-2014-6300]EU, Europeiska forskningsrådet, 335879
    Tillgänglig från: 2018-05-09 Skapad: 2018-05-09 Senast uppdaterad: 2019-06-19Bibliografiskt granskad
    3. On rectification of ionic current in nanopores
    Öppna denna publikation i ny flik eller fönster >>On rectification of ionic current in nanopores
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    2019 (Engelska)Ingår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 91, nr 22, s. 14597-14604Artikel i tidskrift (Refereegranskat) Published
    Nationell ämneskategori
    Nanoteknik
    Identifikatorer
    urn:nbn:se:uu:diva-384653 (URN)10.1021/acs.analchem.9b03685 (DOI)000498280100059 ()31644866 (PubMedID)
    Forskningsfinansiär
    Vetenskapsrådet, 621-20146300; 2016/39
    Tillgänglig från: 2019-06-07 Skapad: 2019-06-07 Senast uppdaterad: 2019-12-18Bibliografiskt granskad
    4. Generalized Noise Study of Solid-State Nanopores at Low Frequencies
    Öppna denna publikation i ny flik eller fönster >>Generalized Noise Study of Solid-State Nanopores at Low Frequencies
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    2017 (Engelska)Ingår i: ACS Sensors, ISSN 2379-3694, Vol. 2, nr 2, s. 300-307Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Nanopore technology has been extensively investigated for analysis of biomolecules, and a success story in this field concerns DNA sequencing using a nanopore chip featuring an array of hundreds of biological nanopores (BioNs). Solid-state nanopores (SSNs) have been explored to attain longer lifetime and higher integration density than what BioNs can offer, but SSNs are generally considered to generate higher noise whose origin remains to be confirmed. Here, we systematically study lowfrequency (including thermal and flicker) noise characteristics of SSNs measuring 7 to 200 nm in diameter drilled through a 20-nmthick SiNx membrane by focused ion milling. Both bulk and surface ionic currents in the nanopore are found to contribute to the flicker noise, with their respective contributions determined by salt concentration and pH in electrolytes as well as bias conditions. Increasing salt concentration at constant pH and voltage bias leads to increase in the bulk ionic current and noise therefrom. Changing pH at constant salt concentration and current bias results in variation of surface charge density, and hence alteration of surface ionic current and noise. In addition, the noise from Ag/AgCl electrodes can become predominant when the pore size is large and/or the salt concentration is high. Analysis of our comprehensive experimental results leads to the establishment of a generalized nanopore noise model. The model not only gives an excellent account of the experimental observations, but can also be used for evaluation of various noise components in much smaller nanopores currently not experimentally available.

    Nyckelord
    flicker noise, nanopore, electrical double layer, model, power spectrum density, low frequency range, Hooge’s theory
    Nationell ämneskategori
    Annan elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-315230 (URN)10.1021/acssensors.6b00826 (DOI)000395047000017 ()
    Forskningsfinansiär
    Vetenskapsrådet, 621-2014-6300Stiftelsen Olle Engkvist Byggmästare, 2016/39Stiftelsen för strategisk forskning (SSF)
    Anmärkning

    Chenyu Wen and Shuangshuang Zeng contributed equally to this work.

    Tillgänglig från: 2017-02-10 Skapad: 2017-02-10 Senast uppdaterad: 2019-12-16Bibliografiskt granskad
    5. On nanopore DNA sequencing by signal and noise analysis of ionic current
    Öppna denna publikation i ny flik eller fönster >>On nanopore DNA sequencing by signal and noise analysis of ionic current
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    2016 (Engelska)Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 27, artikel-id 215502Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    DNA sequencing, i.e., the process of determining the succession of nucleotides on a DNA strand, has become a standard aid in biomedical research and is expected to revolutionize medicine. With the capability of handling single DNA molecules, nanopore technology holds high promises to become speedier in sequencing at lower cost than what are achievable with the commercially available optics-or semiconductor-based massively parallelized technologies. Despite tremendous progress made with biological and solid-state nanopores, high error rates and large uncertainties persist with the sequencing results. Here, we employ a nano-disk model to quantitatively analyze the sequencing process by examining the variations of ionic current when a DNA strand translocates a nanopore. Our focus is placed on signal-boosting and noise-suppressing strategies in order to attain the single-nucleotide resolution. Apart from decreasing pore diameter and thickness, it is crucial to also reduce the translocation speed and facilitate a stepwise translocation. Our best-case scenario analysis points to severe challenges with employing plain nanopore technology, i.e., without recourse to any signal amplification strategy, in achieving sequencing with the desired single-nucleotide resolution. A conceptual approach based on strand synthesis in the nanopore of the translocating DNA from single-stranded to double-stranded is shown to yield a 10-fold signal amplification. Although it involves no advanced physics and is very simple in mathematics, this simple model captures the essence of nanopore sequencing and is useful in guiding the design and operation of nanopore sequencing.

    Nyckelord
    nanopore; DNA sequencing; ionic current; model; series resistance; noise; signal
    Nationell ämneskategori
    Annan elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-295968 (URN)10.1088/0957-4484/27/21/215502 (DOI)000374507600013 ()27095148 (PubMedID)
    Forskningsfinansiär
    Vetenskapsrådet, 621-2014-6300
    Tillgänglig från: 2016-06-11 Skapad: 2016-06-11 Senast uppdaterad: 2019-06-19Bibliografiskt granskad
    6. Rectification of protein translocation in truncated-pyramidal nanopores
    Öppna denna publikation i ny flik eller fönster >>Rectification of protein translocation in truncated-pyramidal nanopores
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    2019 (Engelska)Ingår i: Nature Nanotechnology, ISSN 1748-3387, E-ISSN 1748-3395, Vol. 14, s. 1056-1062Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Solid-state nanopore technology presents an emerging single-molecule-based analytical tool for the separation and analysis of nanoparticles. Different approaches have been pursued to attain the anticipated detection performance. Here, we report the rectification behaviour of protein translocation through silicon-based truncated pyramidal nanopores. When the size of translocating proteins is comparable to the smallest physical constriction of the nanopore, the frequency of translocation events observed is lower for proteins that travel from the larger to the small opening of the nanopore than for those that travel in the reverse direction. When the proteins are appreciably smaller than the nanopore, an opposite rectification in the frequency of translocation events is evident. The maximum rectification factor achieved is around ten. Numerical simulations reveal the formation of an electro-osmotic vortex in such asymmetric nanopores. The vortex–protein interaction is found to play a decisive role in rectifying the translocation in terms of polarity and amplitude. The reported phenomenon can be potentially exploitable for the discrimination of various nanoparticles.

    Nationell ämneskategori
    Nanoteknik Teknik och teknologier
    Identifikatorer
    urn:nbn:se:uu:diva-384656 (URN)10.1038/s41565-019-0549-0 (DOI)000495608700014 ()31591525 (PubMedID)
    Forskningsfinansiär
    Vetenskapsrådet, 621-2014-6300Vetenskapsrådet, 2016/39
    Tillgänglig från: 2019-06-07 Skapad: 2019-06-07 Senast uppdaterad: 2019-12-16Bibliografiskt granskad
    7. Autogenic analyte translocation in nanopores
    Öppna denna publikation i ny flik eller fönster >>Autogenic analyte translocation in nanopores
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    2019 (Engelska)Ingår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, s. 503-509Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Nanopores have been widely studied for power generation and single-molecule detection. Although the power level generated by a single nanopore based on electrolyte concentration gradient is too low to be practically useful, such a power level is found sufficient to drive analyte translocation in nanopores. Here, we explore the simultaneous action of a solid-state nanopore as a nanopower generator and a nanoscale biosensor by exploiting the extremely small power generated to drive the analyte translocation in the same nanopore device. This autogenic analyte translocation is demonstrated using protein and DNA for their distinct shape, size and charge. The simple device structure allows for easy implementation of either electrical or optical readout. The obtained nanopore translocation is characterized by typical behaviors expected for an ordinary nanopore sensor powered by an external source. Extensive numerical simulation confirms the power generation and power level generated. It also reveals the fundamentals of autogenic translocation. As it requires no external power source, the sensing can be conducted with simple readout electronics and may allow for integration of high-density nanopores. Our approach demonstrated in this work may pave the way to practical high-throughput single-molecule nanopore sensing powered by the distributed energy harvested by the nanopores themselves.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2019
    Nationell ämneskategori
    Nanoteknik
    Identifikatorer
    urn:nbn:se:uu:diva-384648 (URN)10.1016/j.nanoen.2019.03.092 (DOI)000467774100056 ()
    Forskningsfinansiär
    Vetenskapsrådet, 621-2014-6300Stiftelsen Olle Engkvist Byggmästare, 2016/39
    Tillgänglig från: 2019-06-07 Skapad: 2019-06-07 Senast uppdaterad: 2019-06-19Bibliografiskt granskad
    8. Group behavior of nanoparticles translocating multiple nanopores
    Öppna denna publikation i ny flik eller fönster >>Group behavior of nanoparticles translocating multiple nanopores
    2018 (Engelska)Ingår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 90, nr 22, s. 13483-13490Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Nanopores have been implemented as nanosensors for DNA sequencing, biomolecule inspection, chemical analysis, nanoparticle detection, etc. For high-throughput and parallelized measurement using nanopore arrays, individual addressability has been a crucial technological solution in order to enable scrutiny of signals generated at each and every nanopore. Here, an alternative pathway of employing arrayed nanopores to perform sensor functions is investigated by examining the group behavior of nanoparticles translocating multiple nanopores. As no individual addressability is required, fabrication of nanopore devices along with microfluidic cells and readout circuits can be greatly simplified. Experimentally, arrays of less than 10 pores are shown to be capable of analyzing translocating nanoparticles with a good signal-to-noise margin. According to theoretical predictions, more pores (than 10) per array can perform high-fidelity analysis if the noise level of the measurement system can be better controlled. More pores per array would also allow for faster measurement at lower concentration because of larger capture cross sections for target nanoparticles. By experimentally varying the number of pores, the concentration of nanoparticles, or the applied bias voltage across the nanopores, we have identified the basic characteristics of this multievent process. By characterizing average pore current and associated standard deviation during translocation and by performing physical modeling and extensive numerical simulations, we have shown the possibility of determining the size and concentration of two kinds of translocating nanoparticles over 4 orders of magnitude in concentration. Hence, we have demonstrated the potential and versatility of the multiple-nanopore approach for high-throughput nanoparticle detection.

    Ort, förlag, år, upplaga, sidor
    Washington: American Chemical Society (ACS), 2018
    Nationell ämneskategori
    Nanoteknik
    Identifikatorer
    urn:nbn:se:uu:diva-369418 (URN)10.1021/acs.analchem.8b03408 (DOI)000451246100048 ()30372031 (PubMedID)
    Forskningsfinansiär
    Vetenskapsrådet, 621-2014-6300Stiftelsen Olle Engkvist Byggmästare, 2016/39
    Tillgänglig från: 2018-12-13 Skapad: 2018-12-13 Senast uppdaterad: 2019-12-16Bibliografiskt granskad
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  • 62.
    Johansson, Oscar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wassénius, Lucas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Estimation of Orientation in a Dual-Tag Ultra Wideband Indoor Positioning System2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this report the feasibility of using a dual-tag setup in an indoor positioning system was investigated. The reason for the dual-tag setup was to be able to estimate both position and orientation. The system was designed using UWB-technology, with an time of flight trilateration algorithm to calculate the position. The orientation was then estimated from the relative position between the two tags. The system was tested both with stationary tags, but also with the tags moving along two paths. These tests were conducted for different separation distance between the tags, namely 20 cm, 30 cm and 40 cm. The result was that the mean position error for stationary tags was less than 8 cm for all separations and the mean orientation error was less than 3$^\circ$ for all separations. For the moving tag tests a decrease of the error in orientation of about 30 \% could be observed for a separation of 30 and 40 cm compared to 20 cm. However this difference is small in absolute values so more tests are needed to draw any conclusion about whether 30 and 40 cm tag separation performs better than 20 cm tag separation. The performance of the system could also be increased further by optimizing the anchor placement as well as the calibration of the antenna delays of the UWB-modules. 

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  • 63.
    Aboulfadl, Hisham
    et al.
    Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden.
    Keller, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Larsen, Jes K
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Thuvander, Mattias
    Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Platzer Björkman, Charlotte
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Microstructural Characterization of Sulfurization Effects in Cu(In,Ga)Se-2 Thin Film Solar Cells2019Ingår i: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 25, nr 2, s. 532-538Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface sulfurization of Cu(In,Ga)Se-2 (CIGSe) absorbers is a commonly applied technique to improve the conversion efficiency of the corresponding solar cells, via increasing the bandgap towards the heterojunction. However, the resulting device performance is understood to be highly dependent on the thermodynamic stability of the chalcogenide structure at the upper region of the absorber. The present investigation provides a high-resolution chemical analysis, using energy dispersive X-ray spectrometry and laser-pulsed atom probe tomography, to determine the sulfur incorporation and chemical re-distribution in the absorber material. The post-sulfurization treatment was performed by exposing the CIGSe surface to elemental sulfur vapor for 20 min at 500 degrees C. Two distinct sulfur-rich phases were found at the surface of the absorber exhibiting a layered structure showing In-rich and Ga-rich zones, respectively. Furthermore, sulfur atoms were found to segregate at the absorber grain boundaries showing concentrations up to similar to 7 at% with traces of diffusion outwards into the grain interior.

  • 64.
    Hedberg, Karolina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Homman, Rebecka
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Konstruktion av EMC-skanner med CoreXY-teknik2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En god elektromagnetisk kompatibilitet (EMC) är en viktig faktor vid konstruktion av kretskort. EMC syftar på ett systems kompatibilitet med sin omgivning och en god EMC innefattar att ett elektriskt system inte interfererar med sig själv eller närliggande system. Kartläggning av EMC kan göras med en EMC-skanner vilken mäter det elektromagnetiska närfältet kring ett mätobjekt. Målet med det här projektet är att konstruera en EMC-skanner vars rörelsemekanism är baserad på CoreXY-teknik. Långsiktigt är målet att skannern ska kunna användas för att skapa 3D-kartor av EMC:n hos kretskort.

    EMC-skannerns mekaniska konstruktion utgick från en design från den digitala plattformen Thingiverse och bestod av aluminiumprofil och delar utskrivna med 3D-skrivare. För mätningar av det elektriska respektive magnetiska närfältet användes en närfältsprob. Rörelsen hos EMC-skannern styrdes av ett styrkort bestående av en Arduino och en RAMPS 1.4 med tre stegmotordrivare. Projektets arbetsgång bestod i att finna en lämplig design av skannern, skriva ut delar med 3D-skrivare, montera skannern, koppla och programmera komponenter för EMC-skannerns styrning samt att utföra en enklare provmätning. Slutprodukten blev en EMC-skanner med fungerande rörelser i x-, y- och z-led och vars rörelsemekanism i xy-planet baserats på CoreXY-teknik. Provmätningar visade att skannern kan användas för att mäta elektriska och magnetiska närfält från ett plant mätobjekt förutsatt att närfältsproben placeras tillräckligt nära detta. För att effektivt kunna använda EMC-skannern för att utföra mätningar på kretskort krävs vidareutveckling främst av skannerns styrning.   

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  • 65.
    Jablonka, Lukas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Contacts and Interconnects for Germanium-based Monolithic 3D Integrated Circuits2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Three-dimensional integrated circuits have great potential for further increasing the number of transistors per area by stacking several device tiers on top of each other and without the need to continue the evermore complicated and expensive down-scaling of transistor dimensions. Among the different approaches towards the realization of such circuits, the monolithic approach, i.e. the tier-by-tier fabrication on a single substrate, is the most promising one in terms of integration density. Germanium is chosen as a substrate material instead of silicon in order to take advantage of its low fabrication temperatures as well as its high carrier mobilities. In this thesis, the work on two key components for the realization of such germanium-based three-dimensional integrated circuits is presented:the source/drain contacts to germanium the interconnects.

    As a potential source/drain contact material, nickel germanide is investigated.In particular, the process temperature windows for the fabrication of morphologically stable nickel germanide layers formed from initial nickel layers below 10 nm are identified and the reaction between nickel and germanium is further studied by means of in-situ x-ray diffraction. The agglomeration temperature of nickel germanide is increased by 100 °C by the addition of tantalum and tungsten interlayers and capping layers. In an effort to more thoroughly characterize the contacts, a method to reliably extract the specific contact resistivity is implemented on germanium.

    As a potential interconnect material cobalt is investigated. In a first step, highly conductive cobalt thin films are demonstrated by means of high-power impulse magnetron sputtering. The high conductivity of the cobalt films is owing to big grains, high density, high purity, and smooth interfaces. In a second step, the potential of high-power impulse magnetron sputtering for the metallization of nanostructures is further explored.

    Delarbeten
    1. Formation of nickel germanides from Ni layers with thickness below 10 nm
    Öppna denna publikation i ny flik eller fönster >>Formation of nickel germanides from Ni layers with thickness below 10 nm
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    2017 (Engelska)Ingår i: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 35, nr 2, artikel-id 020602Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The authors have studied the reaction between a Ge (100) substrate and thin layers of Ni ranging from 2 to 10 nm in thickness. The formation of metal-rich Ni5Ge3 was found to precede that of the monogermanide NiGe by means of real-time in situ x-ray diffraction during ramp-annealing and ex situ x-ray pole figure analyses for phase identification. The observed sequential growth of Ni5Ge3 and NiGe with such thin Ni layers is different from the previously reported simultaneous growth with thicker Ni layers. The phase transformation from Ni5Ge3 to NiGe was found to be nucleationcontrolled for Ni thicknesses < 5 nm, which is well supported by thermodynamic considerations. Specifically, the temperature for the NiGe formation increased with decreasing Ni (rather Ni5Ge3) thickness below 5 nm. In combination with sheet resistance measurement and microscopic surface inspection of samples annealed with a standard rapid thermal processing, the temperature range for achieving morphologically stable NiGe layers was identified for this standard annealing process. As expected, it was found to be strongly dependent on the initial Ni thickness.

    Ort, förlag, år, upplaga, sidor
    A V S AMER INST PHYSICS, 2017
    Nationell ämneskategori
    Materialteknik
    Identifikatorer
    urn:nbn:se:uu:diva-320866 (URN)10.1116/1.4975152 (DOI)000397858500029 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), SE13-0033 RIF14-0053Vetenskapsrådet, C0514401
    Tillgänglig från: 2017-04-26 Skapad: 2017-04-26 Senast uppdaterad: 2019-06-13Bibliografiskt granskad
    2. Improving the morphological stability of nickel germanide by tantalum and tungsten additions
    Öppna denna publikation i ny flik eller fönster >>Improving the morphological stability of nickel germanide by tantalum and tungsten additions
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    2018 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, nr 10, artikel-id 103102Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    To enhance the morphological stability of NiGe, a material of interest as a source drain-contact in Ge-based field effect transistors, Ta or W, is added as either an interlayer or a capping layer. The efficacy of this Ta or W addition is evaluated with pure NiGe as a reference. While interlayers increase the NiGe formation temperature, capping layers do not retard the NiGe formation. Regardless of the initial position of Ta or W, the morphological stability of NiGe against agglomeration can be improved by up to 100 °C. The improved thermal stability can be ascribed to an inhibited surface diffusion, owing to Ta or W being located on top of NiGe after annealing, as confirmed by means of transmission electron microscopy, Rutherford backscattering spectrometry, and atom probe tomography. The latter also shows a 0.3 €‰at. % solubility of Ta in NiGe at 450 °C, while no such incorporation of W is detectable.

    Nationell ämneskategori
    Annan elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-344676 (URN)10.1063/1.5019440 (DOI)000427031300021 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), SE13- 0033Stiftelsen för strategisk forskning (SSF), RIF14- 0053Vetenskapsrådet, C0514401
    Tillgänglig från: 2018-03-07 Skapad: 2018-03-07 Senast uppdaterad: 2019-06-28Bibliografiskt granskad
    3. A novel route to a reliable extraction of the specific contact resistivity of the germanium/nickel germanide interface
    Öppna denna publikation i ny flik eller fönster >>A novel route to a reliable extraction of the specific contact resistivity of the germanium/nickel germanide interface
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    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-385286 (URN)
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), SE13-0333
    Tillgänglig från: 2019-06-13 Skapad: 2019-06-13 Senast uppdaterad: 2019-06-22
    4. Highly conductive ultrathin Co films by high-power impulse magnetron sputtering
    Öppna denna publikation i ny flik eller fönster >>Highly conductive ultrathin Co films by high-power impulse magnetron sputtering
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    2018 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, nr 4, artikel-id 043103Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Ultrathin Co films deposited on SiO2 with conductivities exceeding that of Cu are demonstrated. Ionized deposition implemented by high-power impulse magnetron sputtering (HiPIMS) is shown to result in smooth films with large grains and low resistivities, namely, 14 mu Omega cm at a thickness of 40 nm, which is close to the bulk value of Co. Even at a thickness of only 6 nm, a resistivity of 35 mu Omega cm is obtained. The improved film quality is attributed to a higher nucleation density in the Co-ion dominated plasma in HiPIMS. In particular, the pulsed nature of the Co flux as well as shallow ion implantation of Co into SiO2 can increase the nucleation density. Adatom diffusion is further enhanced in the ionized process, resulting in a dense microstructure. These results are in contrast to Co deposited by conventional direct current magnetron sputtering where the conductivity is reduced due to smaller grains, voids, rougher interfaces, and Ar incorporation. The resistivity of the HiPIMS films is shown to be in accordance with models by Mayadas-Shatzkes and Sondheimer which consider grain-boundary and surface-scattering.

    Ort, förlag, år, upplaga, sidor
    American Institute of Physics (AIP), 2018
    Nationell ämneskategori
    Annan elektroteknik och elektronik Materialkemi
    Identifikatorer
    urn:nbn:se:uu:diva-340315 (URN)10.1063/1.5011109 (DOI)000423724300039 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), SE13-0033Stiftelsen för strategisk forskning (SSF), RIF14-0053Vetenskapsrådet, C0514401
    Tillgänglig från: 2018-01-29 Skapad: 2018-01-29 Senast uppdaterad: 2019-06-13Bibliografiskt granskad
    5. Metal Filling by High Power Impulse Magnetron Sputtering
    Öppna denna publikation i ny flik eller fönster >>Metal Filling by High Power Impulse Magnetron Sputtering
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    2019 (Engelska)Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 52, nr 36, artikel-id 365202Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    High power impulse magnetron sputtering (HiPIMS) is an emerging thin film deposition technology that provides a highly ionized flux of sputtered species. This makes HiPIMS attractive for metal filling of nanosized holes for highly scaled semiconductor devices. In this work, HiPIMS filling with Cu and Co is investigated. We show that the quality of the hole filling is determined mainly by the fraction of ions in the deposited flux and their energy. The discharge waveforms alone are insufficient to determine the ionization of the metal flux. The experimental results are in a good agreement with Monte-Carlo simulations using the measured flux characteristics. Based on the simulations, strategies to improve the filling are discussed.

    Nyckelord
    metallization, HiPIMS, ionized sputtering
    Nationell ämneskategori
    Annan elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-384881 (URN)10.1088/1361-6463/ab28e2 (DOI)000474655700001 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), SE13-0033
    Tillgänglig från: 2019-06-10 Skapad: 2019-06-10 Senast uppdaterad: 2019-09-17Bibliografiskt granskad
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  • 66.
    Rademacher, Frans
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Larsson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Lundberg, Oskar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Praktisk konstruktion av 8-bitarsdator2019Självständigt arbete på grundnivå (konstnärlig kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En 8-bitarsdator är i dagens samhälle gammal teknik. De kan knappast konkurrera med dagens moderna datorer som arbetar snabbare och med större tal. Genom att del för del ändå konstruera en 8-bitarsdator ges dock än idag stor insikt i hur datorer i allmänhet är konstruerade. Med bakgrundskunskap inom grundläggande digital elektronik kan enskilda moduler förstås, vilket sedan leder till en förståelse för datorn i stort. Detta projekt kretsade alltså kring att konstruera en 8-bitarsdator. Denna dator ska efter projektets slut kunna finnas kvar i syftet att användas i undervisning av digital elektronik. 8-bitarsdatorn innefattar flera moduler som var för sig kan både simuleras i mjukvara och konstrueras för sig. Därefter kunde alla moduler sättas samman. Datorn kan enkelt programmeras för att köra olika program, och kan med hjälp av så kallade flaggor hoppa i programkoden för att upprepa kod. Den resulterade datorn har vissa förbättringspotentialer, men fungerar väl enligt förväntningarna. Med strategiska val av färger på kablage och ett stort antal lysdioder blev datorn lättare att förstå och undersöka.

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  • 67.
    Jablonka, Lukas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Moskovkin, Pavel
    Laboratoire d'Analyse par Réactions Nucléaires (LARN), Namur Institute of Structured Matter (NISM), University of Namur (UNamur), Namur, Belgium.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Lucas, Stéphane
    Laboratoire d'Analyse par Réactions Nucléaires (LARN), Namur Institute of Structured Matter (NISM), University of Namur (UNamur), Namur, Belgium.
    Kubart, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Metal Filling by High Power Impulse Magnetron Sputtering2019Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 52, nr 36, artikel-id 365202Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High power impulse magnetron sputtering (HiPIMS) is an emerging thin film deposition technology that provides a highly ionized flux of sputtered species. This makes HiPIMS attractive for metal filling of nanosized holes for highly scaled semiconductor devices. In this work, HiPIMS filling with Cu and Co is investigated. We show that the quality of the hole filling is determined mainly by the fraction of ions in the deposited flux and their energy. The discharge waveforms alone are insufficient to determine the ionization of the metal flux. The experimental results are in a good agreement with Monte-Carlo simulations using the measured flux characteristics. Based on the simulations, strategies to improve the filling are discussed.

  • 68.
    Wen, Chenyu
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Li, Shiyu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zeng, Shuangshuang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Autogenic analyte translocation in nanopores2019Ingår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, s. 503-509Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanopores have been widely studied for power generation and single-molecule detection. Although the power level generated by a single nanopore based on electrolyte concentration gradient is too low to be practically useful, such a power level is found sufficient to drive analyte translocation in nanopores. Here, we explore the simultaneous action of a solid-state nanopore as a nanopower generator and a nanoscale biosensor by exploiting the extremely small power generated to drive the analyte translocation in the same nanopore device. This autogenic analyte translocation is demonstrated using protein and DNA for their distinct shape, size and charge. The simple device structure allows for easy implementation of either electrical or optical readout. The obtained nanopore translocation is characterized by typical behaviors expected for an ordinary nanopore sensor powered by an external source. Extensive numerical simulation confirms the power generation and power level generated. It also reveals the fundamentals of autogenic translocation. As it requires no external power source, the sensing can be conducted with simple readout electronics and may allow for integration of high-density nanopores. Our approach demonstrated in this work may pave the way to practical high-throughput single-molecule nanopore sensing powered by the distributed energy harvested by the nanopores themselves.

  • 69.
    Zeng, Shuangshuang
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wen, Chenyu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Solomon, Paul
    IBM TJ Watson Res Ctr, Yorktown Hts, NY USA.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Rectification of protein translocation in truncated-pyramidal nanopores2019Ingår i: Nature Nanotechnology, ISSN 1748-3387, E-ISSN 1748-3395, Vol. 14, s. 1056-1062Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Solid-state nanopore technology presents an emerging single-molecule-based analytical tool for the separation and analysis of nanoparticles. Different approaches have been pursued to attain the anticipated detection performance. Here, we report the rectification behaviour of protein translocation through silicon-based truncated pyramidal nanopores. When the size of translocating proteins is comparable to the smallest physical constriction of the nanopore, the frequency of translocation events observed is lower for proteins that travel from the larger to the small opening of the nanopore than for those that travel in the reverse direction. When the proteins are appreciably smaller than the nanopore, an opposite rectification in the frequency of translocation events is evident. The maximum rectification factor achieved is around ten. Numerical simulations reveal the formation of an electro-osmotic vortex in such asymmetric nanopores. The vortex–protein interaction is found to play a decisive role in rectifying the translocation in terms of polarity and amplitude. The reported phenomenon can be potentially exploitable for the discrimination of various nanoparticles.

  • 70.
    Wen, Chenyu
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zeng, Shuangshuang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Li, Shiyu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    On rectification of ionic current in nanopores2019Ingår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 91, nr 22, s. 14597-14604Artikel i tidskrift (Refereegranskat)
  • 71.
    Mathur, Parul
    et al.
    Amrita Vishwa Vidyapeetham, RF & Wireless Syst Lab, Dept Elect & Commun Engn, Sch Engn, Bengaluru, India.
    Perez, Mauricio D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Augustine, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Kurup, Dhanesh G.
    Amrita Vishwa Vidyapeetham, RF & Wireless Syst Lab, Dept Elect & Commun Engn, Sch Engn, Bengaluru, India.
    NDECOAX: A software package for nondestructive evaluation of stratified dielectric media2019Ingår i: SoftwareX, E-ISSN 2352-7110, Vol. 9, s. 187-192Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents a software package based on the C++ language for accurate computation of material properties of a stratified media using an open ended coaxial probe (OECP). Since OECP is one of the most commonly used sensors for evaluation of materials today, the program developed can be customized for real time nondestructive evaluation of materials. The main contribution of this article is a computationally efficient software for solving an infinite domain integral with multiple singularities based on plane wave spectrum theory. The computed results for aperture admittance of the coaxial probe using the developed software show good agreement with both measurements and results from a commercial solver using the finite element method (FEM). It is also proved that, the execution time per frequency point of the developed code is much faster than FEM. (C) 2019 The Authors. Published by Elsevier B.V.

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  • 72.
    Teixeira, J. P.
    et al.
    Univ Aveiro, Dept Fis & I3N, P-3810193 Aveiro, Portugal.
    Salome, P. M. P.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal;Univ Aveiro, Dept Fis, P-3810193 Aveiro, Portugal.
    Alves, B.
    Univ Aveiro, Dept Fis & I3N, P-3810193 Aveiro, Portugal.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Leitao, J. P.
    Univ Aveiro, Dept Fis & I3N, P-3810193 Aveiro, Portugal.
    Evidence of Limiting Effects of Fluctuating Potentials on V-OC of Cu(In, Ga)Se-2 Thin-Film Solar Cells2019Ingår i: Physical Review Applied, E-ISSN 2331-7019, Vol. 11, nr 5, artikel-id 054013Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper we present a consistent theoretical approach and an extensive experimental study of Cu(In, Ga)Se-2- (CIGS-)based solar cells to investigate the influence of fluctuating potentials on the limitations of solar-cell performance. The absorptance is calculated for extensions to the Shockley-Queisser model involving the description of tail states under the Urbach-rule, optimal-fluctuation-theory, and bandgap-fluctuation models, as well as the expected values for the saturation current density, short-circuit current density, and open-circuit voltage (V-OC). Three CIGS-based solar cells with [Cu]/([Ga]+[In]) ratios of 0.53, 0.71, and 0.84 are grown to intentionally have sufficiently different amplitudes of fluctuating potentials. We show both theoretically and experimentally the role played by fluctuating potentials, in particular in the V-OC losses. We provide evidence for a higher degree of correlation of electrostatic fluctuating potentials with V-OC losses in comparison with band-gap fluctuations. Additionally, our results show the influence of fluctuating potentials not just at low temperature but also at room temperature.

  • 73.
    Smolarczyk, Marek
    et al.
    Institute of Nanostructure Technologies and Analytics (INA) and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), Heinrich‐Plett‐Strasse 40, 34132 Kassel, Germany.
    Jablonka, Lukas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Institute of Nanostructure Technologies and Analytics (INA) and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), Heinrich‐Plett‐Strasse 40, 34132 Kassel, Germany.
    Reuter, Sabrina
    Institute of Nanostructure Technologies and Analytics (INA) and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), Heinrich‐Plett‐Strasse 40, 34132 Kassel, Germany.
    Hillmer, Hartmut
    Institute of Nanostructure Technologies and Analytics (INA) and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), Heinrich‐Plett‐Strasse 40, 34132 Kassel, Germany.
    Self-Aligned Molding Technology (SAMT) for Fabrication of 3D Structures with a Foldable Imprint Mold2019Ingår i: Applied Nanoscience, ISSN 2190-5509, E-ISSN 2190-5517, Vol. 9, nr 6, s. 1255-1263Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose self-aligned molding technology (SAMT) as a novel nanoimprint technique with a self-aligned foldable imprint mold to control size and shape of structures and particles for a broad range of materials. SAMT is a single-step molding process for complex 3D shaped structures and particles using a reusable double-sided mold with a hinge. We present the fabrication process of SAMT molds, including electron beam lithography on a sloped surface, angular dry etching, and a template-based double inversion technique. We present fabricated SAMT molds and molding results of micro-scale 3D structures.

  • 74.
    Larsen, Jes K
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Larsson, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Törndahl, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Saini, Nishant
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Ren, Yi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Midsummer AB, Elect Hojden 6, S-17543 Jarfalla, Sweden.
    Biswal, Adyasha
    KIT, Inst Photon Sci & Synchrotron Radiat IPS, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany;KIT, Inst Chem Technol & Polymer Chem ITCP, Engesserstr 18-20, D-76128 Karlsruhe, Germany.
    Hauschild, Dirk
    KIT, Inst Photon Sci & Synchrotron Radiat IPS, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany;KIT, Inst Chem Technol & Polymer Chem ITCP, Engesserstr 18-20, D-76128 Karlsruhe, Germany.
    Weinhardt, Lothar
    KIT, Inst Photon Sci & Synchrotron Radiat IPS, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany;KIT, Inst Chem Technol & Polymer Chem ITCP, Engesserstr 18-20, D-76128 Karlsruhe, Germany;Univ Nevada, Dept Chem & Biochem, Las Vegas UNLV, 4505 Maryland Pkwy, Las Vegas, NV 89154 USA.
    Heske, Clemens
    KIT, Inst Photon Sci & Synchrotron Radiat IPS, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany;KIT, Inst Chem Technol & Polymer Chem ITCP, Engesserstr 18-20, D-76128 Karlsruhe, Germany;Univ Nevada, Dept Chem & Biochem, Las Vegas UNLV, 4505 Maryland Pkwy, Las Vegas, NV 89154 USA.
    Platzer Björkman, Charlotte
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Cadmium Free Cu2ZnSnS4 Solar Cells with 9.7% Efficiency2019Ingår i: Advanced Energy Material, ISSN 1614-6832, Vol. 9, nr 21, artikel-id 1900439Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cu2ZnSnS4(CZTS) thin-film solar cell absorbers with different bandgaps can be produced by parameter variation during thermal treatments. Here, the effects of varied annealing time in a sulfur atmosphere and an ordering treatment of the absorber are compared. Chemical changes in the surface due to ordering are examined, and a downshift of the valence band edge is observed. With the goal to obtain different band alignments, these CZTS absorbers are combined with Zn1−xSnxOy (ZTO) or CdS buffer layers to produce complete devices. A high open circuit voltage of 809 mV is obtained for an ordered CZTS absorber with CdS buffer layer, while a 9.7% device is obtained utilizing a Cd free ZTO buffer layer. The best performing devices are produced with a very rapid 1 min sulfurization, resulting in very small grains.

    Ladda ner fulltext (pdf)
    fulltext
  • 75.
    Malyi, Oleksandr, I
    et al.
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, POB 1048, NO-0316 Oslo, Norway.
    Sopiha, Kostiantyn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Persson, Clas
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, POB 1048, NO-0316 Oslo, Norway.
    Noble gas as a functional dopant in ZnO2019Ingår i: NPJ COMPUTATIONAL MATERIALS, ISSN 2057-3960, Vol. 5, artikel-id 38Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Owing to fully occupied orbitals, noble gases are considered to be chemically inert and to have limited effect on materials properties under standard conditions. However, using first-principles calculations, we demonstrate herein that the insertion of noble gas (i.e. He, Ne, or Ar) in ZnO results in local destabilization of electron density of the material driven by minimization of an unfavorable overlap of atomic orbitals of the noble gas and its surrounding atoms. Specifically, the noble gas defect (interstitial or substitutional) in ZnO pushes the electron density of its surrounding atoms away from the defect. Simultaneously, the host material confines the electron density of the noble gas. As a consequence, the interaction of He, Ne, or Ar with O vacancies of ZnO in different charge states q (ZnO:V-O(q)) affects the vacancy stability and their electronic structures. Remarkably, we find that the noble gas is a functional dopant that can delocalize the deep in-gap V-O(q) states and lift electrons associated with the vacancy to the conduction band.

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    FULLTEXT01
  • 76.
    Zhao, Jie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Solution-Processable Conductive Graphene-Based Materials for Flexible Electronics2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis work explores electrical conductors based on few-layer graphene flakes as an enabler for low-cost, mechanically flexible, and high-conductivity conductors in large area flexible and printed electronic devices. The flakes are deposited from aqueous solutions and processed at low temperature.

    Graphene is selected for its excellent properties in mechanical, optical, electronic, and electrical aspects. However, thin films of pristine few-layer graphene flakes deposited from dispersions normally exhibit inferior electrical conductivity. One cause responsible for this problem is the loose stacking and random orientation of graphene flakes in a graphene deposition. We have solved this problem by implementing a simple post-deposition treatment leading to dramatically densified and planarized thin films. Significantly increased electrical conductivity by ~20 times is obtained. The 1-pyrenebutyric acid tetrabutylammonium salt as an exfoliation enhancer and dispersant in water yields ~110 S/m in conductivity when the graphene based thin films are processed at 90 °C. In order to achieve higher conductivity, a room-temperature method for site-selective copper electroless deposition has been developed. This method is of particular interest for the self-aligned copper deposition to the predefined graphene films. The resultant two-layer graphene/copper structure is characterized by an overall conductivity of ~7.9 × 105 S/m, an increase by ~7000 times from the template graphene films. Several electronic circuits based on the graphene/copper bilayer interconnect have been subsequently fabricated on plastic foils as proof-of-concept demonstrators. Alternatively, highly conductive composites featuring graphene flakes coated with silver nanoparticles with electrical conductivity beyond 106 S/m can be readily obtained at 100 oC. Moreover, a highly conductive reduced-graphene-oxide/copper hybrid hydrogel has been achieved by mixing aqueous graphene oxide solution and copper-containing Fehling's solution. The corresponding aerogel of high porosity exhibits an apparent electrical conductivity of ~430 S/m and delivers a specific capacity of ~453 mAh g−1 at current density of 1 A/g. The experimental results presented in this thesis show that the solution-phase, low-temperature fabrication of highly conductive graphene-based materials holds promises for flexible electronics and energy storage applications. 

    Delarbeten
    1. Re-organized graphene nanoplatelet thin films achieved by a two-step hydraulic method
    Öppna denna publikation i ny flik eller fönster >>Re-organized graphene nanoplatelet thin films achieved by a two-step hydraulic method
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    2018 (Engelska)Ingår i: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 84, s. 141-145Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Film deposition of graphene nanoplatelets (GNPs) from dispersion via casting and printing approaches features cost- and material-efficiency, however, it usually suffers from poor uniformity, rough surface and loose flake stacking due to adverse effect of hydraulic force. Here, a simple two-step method exploiting hydraulic force is presented to readily deliver GNP films of improved quality from an aqueous dispersion. While as-deposited GNP films exhibit the aforementioned film defects, the hydraulic force in the subsequent step constituting soaking in water and drying leads to an efficient re-organization of the individual GNPs in the films, The majority of GNPs thus are oriented horizontally and closely stacked. As a result, densified, smoothened and homogenized GNP thin films can be readily achieved. The GNP re-organization reduces resistivity from > 1 Omega cm to 10(-2) Omega cm. The method developed is universally applicable to solution-phase film deposition of 2D materials.

    Ort, förlag, år, upplaga, sidor
    ELSEVIER SCIENCE SA, 2018
    Nationell ämneskategori
    Kompositmaterial och -teknik
    Identifikatorer
    urn:nbn:se:uu:diva-356327 (URN)10.1016/j.diamond.2018.03.016 (DOI)000432101800019 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), Dnr SE13-0061Vetenskapsrådet, 621-2014-5596
    Tillgänglig från: 2018-07-26 Skapad: 2018-07-26 Senast uppdaterad: 2019-04-08Bibliografiskt granskad
    2. A Sequential Process of Graphene Exfoliation and Site-Selective Copper/Graphene Metallization Enabled by Multifunctional 1-Pyrenebutyric Acid Tetrabutylammonium Salt
    Öppna denna publikation i ny flik eller fönster >>A Sequential Process of Graphene Exfoliation and Site-Selective Copper/Graphene Metallization Enabled by Multifunctional 1-Pyrenebutyric Acid Tetrabutylammonium Salt
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    2019 (Engelska)Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 6, s. 6448-6455Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    This paper reports a procedure leading to shear exfoliation of pristine few-layer graphene flakes in water and subsequent site-selective formation of Cu/graphene films on polymer substrates, both of which are enabled by employing the water soluble 1-pyrenebutyric acid tetrabutylammonium salt (PyB-TBA). The exfoliation with PyB-TBA as an enhancer leads to as-deposited graphene films dried at 90 °C that are characterized by electrical conductivity of ∼110 S/m. Owing to the good affinity of the tetrabutylammonium cations to the catalyst PdCl42–, electroless copper deposition selectively in the graphene films is initiated, resulting in a self-aligned formation of highly conductive Cu/graphene films at room temperature. The excellent solution-phase and low-temperature processability, self-aligned copper growth, and high electrical conductivity of the Cu/graphene films have permitted fabrication of several electronic circuits on plastic foils, thereby indicating their great potential in compliant, flexible, and printed electronics.

    Nyckelord
    graphene, electroless copper deposition, solution-phase processing, self-aligned metallization, flexible electronics
    Nationell ämneskategori
    Materialkemi Teknik och teknologier
    Identifikatorer
    urn:nbn:se:uu:diva-378999 (URN)10.1021/acsami.8b21162 (DOI)000459221900096 ()30656938 (PubMedID)
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), Dnr SE13-0061Vetenskapsrådet, 621-2014-5596
    Tillgänglig från: 2019-03-19 Skapad: 2019-03-19 Senast uppdaterad: 2020-01-08Bibliografiskt granskad
    3. Microstructure-tunable highly conductive graphene-metal composites achieved by inkjet printing and low temperature annealing
    Öppna denna publikation i ny flik eller fönster >>Microstructure-tunable highly conductive graphene-metal composites achieved by inkjet printing and low temperature annealing
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    2018 (Engelska)Ingår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 28, nr 3, artikel-id 035006Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We present a method for fabricating highly conductive graphene-silver composite films with a tunable microstructure achieved by means of an inkjet printing process and low temperature annealing. This is implemented by starting from an aqueous ink formulation using a reactive silver solution mixed with graphene nanoplatelets (GNPs), followed by inkjet printing deposition and annealing at 100 degrees C for silver formation. Due to the hydrophilic surfaces and the aid of a polymer stabilizer in an aqueous solution, the GNPs are uniformly covered with a silver layer. Simply by adjusting the content of GNPs in the inks, highly conductive GNP/Ag composites (> 106 S m(-1)), with their microstructure changed from a large-area porous network to a compact film, is formed. In addition, the printed composite films show superior quality on a variety of unconventional substrates compared to its counterpart without GNPs. The availability of composite films paves the way to the metallization in different printed devices, e.g. interconnects in printed circuits and electrodes in energy storage devices.

    Ort, förlag, år, upplaga, sidor
    IOP PUBLISHING LTD, 2018
    Nyckelord
    graphene, composite, inkjet printing
    Nationell ämneskategori
    Materialteknik
    Identifikatorer
    urn:nbn:se:uu:diva-345709 (URN)10.1088/1361-6439/aaa450 (DOI)000423867400001 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), Dnr SE13-0061Vetenskapsrådet, 621-2014-5596
    Tillgänglig från: 2018-03-14 Skapad: 2018-03-14 Senast uppdaterad: 2019-04-08Bibliografiskt granskad
    4. High-Conductivity Reduced-Graphene-Oxide/Copper Aerogel for Energy Storage
    Öppna denna publikation i ny flik eller fönster >>High-Conductivity Reduced-Graphene-Oxide/Copper Aerogel for Energy Storage
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    2019 (Engelska)Ingår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, s. 760-767Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    This work reports a room-temperature, solution-phase and one-pot method for macro-assembly of a three-dimensional (3D) reduced-graphene-oxide/copper hybrid hydrogel. The hydrogel is subsequently transformed into a highly conductive aerogel via freeze-drying. The aerogel, featuring reduced graphene oxide (rGO) networks decorated with Cu and CuxO nanoparticles (Cu/CuxO@rGO), exhibits a specific surface area of 48 m2/g and an apparent electrical conductivity of ∼33 and ∼430 S/m prior to and after mechanical compression, respectively. The compressed Cu/CuxO@rGO aerogel delivers a specific capacity of ∼453 mAh g−1 at a current density of 1 A/g and ∼184 mAh g−1 at 50 A/g in a 3 M KOH aqueous electrolyte evidenced by electrochemical measurements. Galvanostatic cycling tests at 5 A/g demonstrates that the Cu/CuxO@rGO aerogel retains 38% (∼129 mAh g−1) of the initial capacity (∼339 mAh g−1) after 500 cycles. The straightforward manufacturing process and the promising electrochemical performances make the Cu/CuxO@rGO aerogel an attractive electrode candidate in energy storage applications.

    Nyckelord
    Reduced graphene oxide, Graphene, Copper, Aerogel, Energy storage, Battery
    Nationell ämneskategori
    Materialkemi Nanoteknik
    Identifikatorer
    urn:nbn:se:uu:diva-381347 (URN)10.1016/j.nanoen.2019.04.023 (DOI)000467774100084 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), Dnr SE13-0061Vetenskapsrådet, 621-2014-5596
    Tillgänglig från: 2019-04-08 Skapad: 2019-04-08 Senast uppdaterad: 2020-05-18Bibliografiskt granskad
    Ladda ner fulltext (pdf)
    fulltext
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    presentationsbild
  • 77.
    Zhao, Jie
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an.
    Pan, Ruijun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Sun, Rui
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Wen, Chenyu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wu, Biao
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Zhang, Zhi-Bin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    High-Conductivity Reduced-Graphene-Oxide/Copper Aerogel for Energy Storage2019Ingår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, s. 760-767Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work reports a room-temperature, solution-phase and one-pot method for macro-assembly of a three-dimensional (3D) reduced-graphene-oxide/copper hybrid hydrogel. The hydrogel is subsequently transformed into a highly conductive aerogel via freeze-drying. The aerogel, featuring reduced graphene oxide (rGO) networks decorated with Cu and CuxO nanoparticles (Cu/CuxO@rGO), exhibits a specific surface area of 48 m2/g and an apparent electrical conductivity of ∼33 and ∼430 S/m prior to and after mechanical compression, respectively. The compressed Cu/CuxO@rGO aerogel delivers a specific capacity of ∼453 mAh g−1 at a current density of 1 A/g and ∼184 mAh g−1 at 50 A/g in a 3 M KOH aqueous electrolyte evidenced by electrochemical measurements. Galvanostatic cycling tests at 5 A/g demonstrates that the Cu/CuxO@rGO aerogel retains 38% (∼129 mAh g−1) of the initial capacity (∼339 mAh g−1) after 500 cycles. The straightforward manufacturing process and the promising electrochemical performances make the Cu/CuxO@rGO aerogel an attractive electrode candidate in energy storage applications.

  • 78.
    Chen, Xi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Silicon Nanowire Field-Effect Devices as Low-Noise Sensors2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In the past decades, silicon nanowire field-effect transistors (SiNWFETs) have been explored for label-free, highly sensitive, and real-time detections of chemical and biological species. The SiNWFETs are anticipated for sensing analyte at ultralow concentrations, even at single-molecule level, owing to their significantly improved charge sensitivity over large-area FETs. In a SiNWFET sensor, a change in electrical potential associated with biomolecular interactions in close proximity to the SiNW gate terminal can effectively control the underlying channel and modulate the drain-to-source current (IDS) of the SiNWFET. A readout signal is therefore generated. This signal is primarily determined by the surface properties of the sensing layer on the gate terminal, with sensitivity close up to the Nernstian limit widely demonstrated. To achieve a high signal-to-noise ratio (SNR), it is essential for the SiNWFETs to possess low noise of which intrinsic device noise is one of the major components. In metal-oxide-semiconductor (MOS)-type FETs, the intrinsic noise mainly results from carrier trapping/detrapping at the gate oxide/semiconductor interface and it is inversely proportional to the device area.

    This thesis presents a comprehensive study on design, fabrication, and noise reduction of SiNWFET-based sensors on silicon-on-oxide (SOI) substrate. A novel Schottky junction gated SiNWFET (SJGFET) is designed and experimentally demonstrated for low noise applications. Firstly, a robust process employing photo- and electron-beam mixed-lithography was developed to reliably produce sub-10 nm SiNW structures for SiNWFET fabrication. For a proof-of-concept demonstration, MOS-type SiNWFET sensors were fabricated and applied for multiplexed ion detection using ionophore-doped mixed-matrix membranes as sensing layers. To address the fundamental noise issue of the MOS-type SiNWFETs, SJGFETs were fabricated with a Schottky (PtSi/silicon) junction gate on the top surface of the SiNW channel, replacing the noisy gate oxide/silicon interface in the MOS-type SiNWFETs. The resultant SJGFETs exhibited a close-to-ideal gate coupling efficiency (60 mV/dec) and significantly reduced device noise compared to reference MOS-type SiNWFETs. Further optimization was performed by implementing a three-dimensional Schottky junction gate wrapping both top surface and two sidewalls of the SiNW channel. The tri-gate SJGFETs with optimized geometry exhibited significantly enhanced electrostatic control over the channel, thereby confined IDS in the SiNW bulk, which greatly improved the device noise immunity to the traps at bottom buried oxide/silicon interface. Finally, a lateral bipolar junction transistor (LBJT) was also designed and fabricated on a SOI substrate aiming for immediate sensor current amplification. Integrating SJGFETs with LBJTs is expected to significantly suppress environmental interference and improve the overall SNR especially under low sensor current situations.

    Delarbeten
    1. Aged hydrogen silsesquioxane for sub-10 nm line patterns
    Öppna denna publikation i ny flik eller fönster >>Aged hydrogen silsesquioxane for sub-10 nm line patterns
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    2016 (Engelska)Ingår i: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 163, s. 105-109Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Hydrogen silsesquioxane (HSQ) has been used as a negative tone resist in electron beam lithography to define sub-10 nm patterns. The spontaneous polymerization in HSQ usually called aging in this context, sets a restricted period of time for a vendor-warranted use in patterning such small features with satisfactory line-edge roughness (LER). Here, we study the effect of HSQ aging on sensitivity and LER by focusing on exposing line patterns of 10 nm width in various structures. The results show that the 10 nm lines are easily achievable and the LER of the patterned lines remains unaltered even with HSQ that is stored 10 months beyond the vendor-specified expiration date. However, an increasingly pronounced decrease with time of the threshold electron dose (D-th), below which the line width would become less than 10 nm, is observed. After the HSQ expiration for 10 months, the 10 nm lines can be manufactured by reducing D-th to a level that is technically manageable with safe margins. In addition, the inclusion of a prebaldng step at 220 degrees C to accelerate the aging process results in a further reduced D-th for the 10 nm lines and thereby leads to a shortened writing time. The time variation of D-th with respect to the vendor-specified production date of HSQ is found to follow an exponential function of time and can be associated to the classical nucleation-growth polymerization process in HSQ.

    Nyckelord
    Electron beam lithography (EBL); Hydrogen silsesquioxane (HSQ); 10 nm wide resist lines; Aging effect; Line edge roughness (LER); Prebaking
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:uu:diva-300188 (URN)10.1016/j.mee.2016.06.011 (DOI)000381837300015 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), ICA 12-0047 SE13-0033Vetenskapsrådet, 2014-5588 2014-5591Göran Gustafssons Stiftelse för främjande av vetenskaplig forskning vid Uppsala universitet och Kungl tekniska högskolan (UU/KTH), GG 1459BCarl Tryggers stiftelse för vetenskaplig forskning , CTS14-527
    Tillgänglig från: 2016-08-04 Skapad: 2016-08-04 Senast uppdaterad: 2019-04-03Bibliografiskt granskad
    2. Multiplexed analysis of molecular and elemental ions using nanowire transistor sensors
    Öppna denna publikation i ny flik eller fönster >>Multiplexed analysis of molecular and elemental ions using nanowire transistor sensors
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    2018 (Engelska)Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 270, s. 89-96Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    An integrated sensor chip with silicon nanowire ion-sensitive field-effect transistors for simultaneous and selective detection of both molecular and elemental ions in a single sample solution is demonstrated. The sensing selectivity is realized by functionalizing the sensor surface with tailor-made mixed-matrix membranes (MMM) incorporated with specific ionophores for the target ions. A biomimetic container molecule, named metal-organic supercontainer (MOSC), is selected as the ionophore for detection of methylene blue (MB+), a molecular ion, while a commercially available Na-ionophore is used for Na+, an elemental ion. The sensors show a near-Nernstian response with 56.4 ± 1.8 mV/dec down to a concentration limit of ∌1 ΌM for MB+ and 57.9 ± 0.7 mV/dec down to ∌60 ΌM for Na+, both with excellent reproducibility. Extensive control experiments on the MB+ sensor lead to identification of the critical role of the MOSC molecules in achieving a stable and reproducible potentiometric response. Moreover, the MB+-specific sensor shows remarkable selectivity against common interfering elemental ions in physiological samples, e.g., H+, Na+, and K+. Although the Na+-specific sensor is currently characterized by insufficient immunity to the interference by MB+, the root cause is identified and remedies generally applicable for hydrophobic molecular ions are discussed. River water experiments are also conducted to prove the efficacy of our sensors.

    Nyckelord
    Elemental ion, ISFET, Metal-organic supercontainer, Molecular ion, Multiplex detection, Silicon nanowire FET
    Nationell ämneskategori
    Annan elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-351716 (URN)10.1016/j.snb.2018.05.018 (DOI)000434011500011 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), SSF ICA 12-0047;FFL15-0174Vetenskapsrådet, VR 2014-5588Göran Gustafssons Stiftelse för främjande av vetenskaplig forskning vid Uppsala universitet och Kungl tekniska högskolan (UU/KTH), GG 1459BCarl Tryggers stiftelse för vetenskaplig forskning , CTS14-527
    Anmärkning

    Xi Chen and Qitao Hu contributed equally to this work

    Tillgänglig från: 2018-05-29 Skapad: 2018-05-29 Senast uppdaterad: 2019-04-03Bibliografiskt granskad
    3. Device noise reduction for Silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate
    Öppna denna publikation i ny flik eller fönster >>Device noise reduction for Silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate
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    2019 (Engelska)Ingår i: ACS sensors, ISSN 2379-3694, Vol. 4, nr 2, s. 427-433Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The sensitivity of metal-oxide-semiconductor field-effect transistor (MOSFET) based nanoscale sensors is ultimately limited by noise induced by carrier trapping/detrapping processes at the gate oxide/semiconductor interfaces. We have designed a Schottky junction gated silicon nanowire field-effect transistor (SiNW-SJGFET) sensor, where the Schottky junction replaces the noisy oxide/semiconductor interface. Our sensor exhibits significantly reduced noise, 2.1×10-9 V2µm2/Hz at 1 Hz, compared to reference devices with the oxide/semiconductor interface operated at both inversion and depletion modes. Further improvement can be anticipated by wrapping the nanowire by such a Schottky junction thereby eliminating all oxide/semiconductor interfaces. Hence, a combination of the low-noise SiNW-SJGFET sensor device with a sensing surface of the Nernstian response limit holds promises for future high signal-to-noise ratio sensor applications.

    Nyckelord
    Noise reduction, schottky junction gate, silicon nanowire, field-effect transistor, low frequency noise, ion sensor
    Nationell ämneskategori
    Nanoteknik Signalbehandling
    Identifikatorer
    urn:nbn:se:uu:diva-374776 (URN)10.1021/acssensors.8b0139 (DOI)000459836400021 ()30632733 (PubMedID)
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), SSF ICA 12-0047Stiftelsen för strategisk forskning (SSF), FFL15-0174Vetenskapsrådet, VR 2014-5588Knut och Alice Wallenbergs Stiftelse
    Tillgänglig från: 2019-01-24 Skapad: 2019-01-24 Senast uppdaterad: 2019-04-03Bibliografiskt granskad
    4. Low-Noise Schottky Junction Trigate Silicon Nanowire Field-effect Transistor for Charge Sensing
    Öppna denna publikation i ny flik eller fönster >>Low-Noise Schottky Junction Trigate Silicon Nanowire Field-effect Transistor for Charge Sensing
    Visa övriga...
    2019 (Engelska)Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 66, nr 9, s. 3994-4000Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Silicon nanowire (SiNW) field-effect transistors (SiNWFETs) are of great potential as a high-sensitivity charge sensor. The signal-to-noise ratio (SNR) of an SiNWFET sensor is ultimately limited by the intrinsic device noise generated by carrier trapping/detrapping processes at the gate oxide/silicon interface. This carrier trapping/detrapping-induced noise can be significantly reduced by replacing the noisy oxide/silicon interface with a Schottky junction gate (SJG) on the top of the SiNW. In this paper, we present a tri-SJG SiNWFET (Tri-SJGFET) with the SJG formed on both the top surface and the two sidewalls of the SiNW so as to enhance the gate control over the SiNW channel. Both experiment and simulation confirm that the additional sidewall gates in a narrow Tri-SJGFET indeed can confine the conduction path within the bulk of the SiNW channel away from the interfaces and significantly improve the immunity to the traps at the bottom buried oxide/silicon interface. Therefore, the optimal low-frequency noise performance can be achieved without the need for any substrate bias. This new gating structure holds promises for further development of robust SiNWFET-based charge sensors with low noise and low operation voltage.

    Nyckelord
    Silicon nanowire field-effect transistor, Schottky junction, trigate, sensor, low-frequency noise, charge sensing
    Nationell ämneskategori
    Elektroteknik och elektronik
    Forskningsämne
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-380971 (URN)10.1109/TED.2019.2930067 (DOI)000482583200046 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), SSF FFL15-0174Vetenskapsrådet, VR 2014-5588Knut och Alice Wallenbergs Stiftelse
    Anmärkning

    Title in thesis list of papers: Low Noise Schottky Junction Tri-gate Silicon Nanowire Field-effect Transistor for Charge Sensing

    Tillgänglig från: 2019-04-02 Skapad: 2019-04-02 Senast uppdaterad: 2019-10-23Bibliografiskt granskad
    5. Top-bottom gate coupling effect on low frequency noise in a Schottky junction gated silicon nanowire field-effect transistor
    Öppna denna publikation i ny flik eller fönster >>Top-bottom gate coupling effect on low frequency noise in a Schottky junction gated silicon nanowire field-effect transistor
    2019 (Engelska)Ingår i: IEEE Journal of the Electron Devices Society, ISSN 2168-6734, Vol. 7, s. 696-700Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this letter, strong low frequency noise (LFN) reduction is observed when the buried oxide (BOX)/silicon interface of a Schottky junction gated silicon nanowire field-effect transistor (SJGFET) is depleted by a substrate bias. Such LFN reduction is mainly attributed to the dramatic reduction in Coulomb scattering when carriers are pushed away from the interface. The BOX/silicon interface depletion can also be achieved by sidewall Schottky junction gates in a narrow channel SJGFET, leading to an optimal LFN performance without the need of any substrate bias.

    Nationell ämneskategori
    Elektroteknik och elektronik
    Forskningsämne
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-380974 (URN)10.1109/JEDS.2019.2929163 (DOI)000478945400003 ()
    Forskningsfinansiär
    Vetenskapsrådet, VR 2014-5588Stiftelsen för strategisk forskning (SSF), FFL15-0174
    Tillgänglig från: 2019-04-02 Skapad: 2019-04-02 Senast uppdaterad: 2019-09-26Bibliografiskt granskad
    6. Current gain and low-frequency noise of symmetriclateral bipolar junction transistors on SOI
    Öppna denna publikation i ny flik eller fönster >>Current gain and low-frequency noise of symmetriclateral bipolar junction transistors on SOI
    Visa övriga...
    2018 (Engelska)Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This paper presents a comprehensive study ofsymmetric lateral bipolar junction transistors (LBJTs) fabricatedon SOI substrate using a CMOS-compatible process; LBJTs findmany applications including being a local signal amplifier forsilicon-nanowire sensors. Our LBJTs are characterized by a peakgain (β) over 50 and low-frequency noise two orders ofmagnitude lower than what typically is of the SiO2/Si interfacefor a MOSFET. β is found to decrease at low base current due torecombination in the space charge region at the emitter-basejunction and at the surrounding SiO2/Si interfaces. This decreasecan be mitigated by properly biasing the substrate.

    Nyckelord
    symmetric lateral bipolar junction transitor; current amplification; low frequency noise; silicon nanowire field-effect transitor
    Nationell ämneskategori
    Annan elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-364155 (URN)
    Konferens
    48th European Solid-State Device Research Conference, September 3 - 6, 2018, Dresden, Germany
    Anmärkning

    Qitao Hu and Xi Chen contribute equally to the work.

    Tillgänglig från: 2018-10-24 Skapad: 2018-10-24 Senast uppdaterad: 2019-04-03Bibliografiskt granskad
    Ladda ner fulltext (pdf)
    fulltext
    Ladda ner (jpg)
    presentationsbild
  • 79.
    Chen, Xi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Chen, Si
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Solomon, Paul
    IBM Corp, Div Res, TJ Watson Res Ctr, Yorktown Hts, NY 10598 USA.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Top-bottom gate coupling effect on low frequency noise in a Schottky junction gated silicon nanowire field-effect transistor2019Ingår i: IEEE Journal of the Electron Devices Society, ISSN 2168-6734, Vol. 7, s. 696-700Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this letter, strong low frequency noise (LFN) reduction is observed when the buried oxide (BOX)/silicon interface of a Schottky junction gated silicon nanowire field-effect transistor (SJGFET) is depleted by a substrate bias. Such LFN reduction is mainly attributed to the dramatic reduction in Coulomb scattering when carriers are pushed away from the interface. The BOX/silicon interface depletion can also be achieved by sidewall Schottky junction gates in a narrow channel SJGFET, leading to an optimal LFN performance without the need of any substrate bias.

    Ladda ner fulltext (pdf)
    fulltext
  • 80.
    Chen, Xi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Chen, Si
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Solomon, Paul
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. IBM Thomas J. Watson Research Center.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Low-Noise Schottky Junction Trigate Silicon Nanowire Field-effect Transistor for Charge Sensing2019Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 66, nr 9, s. 3994-4000Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silicon nanowire (SiNW) field-effect transistors (SiNWFETs) are of great potential as a high-sensitivity charge sensor. The signal-to-noise ratio (SNR) of an SiNWFET sensor is ultimately limited by the intrinsic device noise generated by carrier trapping/detrapping processes at the gate oxide/silicon interface. This carrier trapping/detrapping-induced noise can be significantly reduced by replacing the noisy oxide/silicon interface with a Schottky junction gate (SJG) on the top of the SiNW. In this paper, we present a tri-SJG SiNWFET (Tri-SJGFET) with the SJG formed on both the top surface and the two sidewalls of the SiNW so as to enhance the gate control over the SiNW channel. Both experiment and simulation confirm that the additional sidewall gates in a narrow Tri-SJGFET indeed can confine the conduction path within the bulk of the SiNW channel away from the interfaces and significantly improve the immunity to the traps at the bottom buried oxide/silicon interface. Therefore, the optimal low-frequency noise performance can be achieved without the need for any substrate bias. This new gating structure holds promises for further development of robust SiNWFET-based charge sensors with low noise and low operation voltage.

  • 81.
    Zou, Haiyang
    et al.
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Li, Xiaogan
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Dai, Guozhang
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA;Cent S Univ, Sch Phys & Elect, Hunan Key Lab Super Microstruct & Ultrafast Proc, Changsha 410083, Hunan, Peoples R China.
    Peng, Wenbo
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Ding, Yong
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Zhang, Ying
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Wang, Aurelia Chi
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Zhang, Steven L.
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Xu, Cheng
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA;China Univ Min & Technol, Sch Mat Sci & Engn, Xuzhou 221116, Jiangsu, Peoples R China.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wang, Zhong Lin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA;Chinese Acad Sci, Beijing Inst Nanoenergy & Nanosyst, Beijing 100083, Peoples R China.
    Dramatically Enhanced Broadband Photodetection by Dual Inversion Layers and Fowler-Nordheim Tunneling2019Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 13, nr 2, s. 2289-2297Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silicon photonics is now widely accepted as a key technology in a variety of systems. But owing to material limitations, now it is challenging to greatly improve the performance after decades of development. Here, we show a high-performance broadband photodetector with significantly enhanced sensitivity and responsivity operating over a wide wavelength range of light from near-ultraviolet to near-infrared at low power consumption. The specially designed textured top ceiling electrode works effectively as an antireflection layer to greatly improve the absorption of near-infrared light, thereby overcoming the absorption limitation of near-infrared light. Instead of the conventional p-n junction and p-intrinsic-n junction, we introduce a similar to 15 nm thick alumina insulator layer between a p-type Si substrate and n-type ZnO nanowire (NW) arrays, which significantly enhances the charge carrier separation and collection efficiency. The photosensing responsivity and sensitivity are found to be nearly 1 order of magnitude higher than that of a reference device of p-Si/n-ZnO NW arrays, significantly higher than the commercial silicon photodiodes as well. The light-induced charge carriers flow across the appropriate thickness of insulator layer via the quantum mechanical Fowler-Nordheim tunneling mechanism. By virtue of the piezo-phototronic effect, the charge density at the interfaces can be tuned to alter the energy bands and the potential barrier distance for tunneling. Additionally, along with the use of incident light of different wavelengths, the influence of the insulator layer on the transport of electrons and holes separately is further investigated. The demonstrated concepts and study would lead to sensitivity improvement, quality enhancement of data transfer, decrease of power consumption, and cost reduction of silicon photonics.

  • 82.
    Zhao, Jie
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Northwest Univ, Coll Chem & Mat Sci, Minist Educ, Key Lab Synthet & Nat Funct Mol Chem, Xian, Shaanxi, Peoples R China.
    Wen, Chenyu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Sun, Rui
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wu, Biao
    Northwest Univ, Coll Chem & Mat Sci, Minist Educ, Key Lab Synthet & Nat Funct Mol Chem, Xian, Shaanxi, Peoples R China.
    Zhang, Zhi-Bin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    A Sequential Process of Graphene Exfoliation and Site-Selective Copper/Graphene Metallization Enabled by Multifunctional 1-Pyrenebutyric Acid Tetrabutylammonium Salt2019Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 6, s. 6448-6455Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports a procedure leading to shear exfoliation of pristine few-layer graphene flakes in water and subsequent site-selective formation of Cu/graphene films on polymer substrates, both of which are enabled by employing the water soluble 1-pyrenebutyric acid tetrabutylammonium salt (PyB-TBA). The exfoliation with PyB-TBA as an enhancer leads to as-deposited graphene films dried at 90 °C that are characterized by electrical conductivity of ∼110 S/m. Owing to the good affinity of the tetrabutylammonium cations to the catalyst PdCl42–, electroless copper deposition selectively in the graphene films is initiated, resulting in a self-aligned formation of highly conductive Cu/graphene films at room temperature. The excellent solution-phase and low-temperature processability, self-aligned copper growth, and high electrical conductivity of the Cu/graphene films have permitted fabrication of several electronic circuits on plastic foils, thereby indicating their great potential in compliant, flexible, and printed electronics.

  • 83.
    Donzel-Gargand, Olivier
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Larsson, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Törndahl, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Stolt, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Solibro Research AB, Vallvägen 5, Uppsala,Sweden.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Secondary phase formation and surface modification from a high dose KF-post deposition treatment of (Ag,Cu)(In,Ga)Se-2 solar cell absorbers2019Ingår i: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 27, nr 3, s. 220-228Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, we assessed the potential of KF-post deposition treatment (PDT) performed on a silver-alloyed Cu (In,Ga)Se-2 (ACIGS) solar absorber. ACIGS absorbers with Ag/Ag + Cu ratio (Ag/I) close to 20% were co-evaporated on a Mo-coated glass substrate and exposed to in-situ KF-PDT of various intensities. The current-voltage characteristics indicated that an optimized PDT can be beneficial, increasing in our study the median V-oc and efficiency values by +48 mV and + 0.9%(abs) (from 728 mV and 16.1% efficiency measured for the sample without PDT), respectively. However, an increased KF-flux during PDT resulted in a net deterioration of the performance leading to median V-oc and efficiency values as low as 503 mV and 4.7%. The chemical composition analysis showed that while the reference absorber without any post deposition treatment (PDT) was homogeneous, the KF-PDT induced a clear change within the first 10 nm from the surface. Here, the surface layer composition was richer in K and In with an increased Ag/I ratio, and its thickness seemed to follow the KF exposure intensity. Additionally, high-dose KF-PDT resulted in substantial formation of secondary phases for the ACIGS. The secondary phase precipitates were also richer in Ag, K, and In, and electron and X-ray diffraction data match with the monoclinic C 1 2/c 1 space group adopted by the Ag-alloyed KInSe2 phase. It could not be concluded whether the performance loss for the solar cell devices originated from the thicker surface layer or the presence of secondary phases, or both for the high-dose KF-PDT sample.

  • 84.
    Serrano, Ismael G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Panda, Jaganandha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Denoel, Fernand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Vallin, Örjan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Phuyal, Dibya
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Karis, Olof
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Kamalakar, M. Venkata
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Two-Dimensional Flexible High Diffusive Spin Circuits2019Ingår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 19, nr 2, s. 666-673Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Owing to their unprecedented electronic properties, graphene and two-dimensional (2D) crystals have brought fresh opportunities for advances in planar spintronic devices. Graphene is an ideal medium for spin transport while being an exceptionally resilient material for flexible nanoelectronics. However, these extraordinary traits have never been combined to create flexible graphene spin circuits. Realizing such circuits could lead to bendable strain-spin sensors, as well as a unique platform to explore pure spin current based operations and low-power 2D flexible nanoelectronics. Here, we demonstrate graphene spin circuits on flexible substrates for the first time. Despite the rough topography of the flexible substrates, these circuits prepared with chemical vapor deposited monolayer graphene reveal an efficient room temperature spin transport with distinctively large spin diffusion coefficients ∼0.2 m2 s–1. Compared to earlier graphene devices on Si/SiO2 substrates, such values are up to 20 times larger, leading to one order higher spin signals and an enhanced spin diffusion length ∼10 μm in graphene-based nonlocal spin valves fabricated using industry standard systems. This high performance arising out of a characteristic substrate terrain shows promise of a scalable and flexible platform towards flexible 2D spintronics. Our innovation is a key step for the exploration of strain-dependent 2D spin phenomena and paves the way for flexible graphene spin memory–logic units and planar spin sensors.

  • 85.
    Song, Man
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Graphene Based Inks for Printed Electronics2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The outstanding properties of graphene make it attractive ink filler for conductive inks which plays an important role in printed electronics. This thesis focuses on the ink formulation based on graphene and graphene oxide (GO).

    Liquid phase exfoliation of graphite is employed to prepare graphene dispersions, i.e., shear- and electrochemical exfoliation. High concentration graphene dispersions with small size, few-layer graphene platelets are obtained by both methods. With the addition of ethyl cellulose stabilizer, shear-exfoliated graphene platelets in NMP were successfully inkjet printed on different substrates. The printed graphene film with electrical conductivity of ~3^104 S/m was obtained after annealing at 350 °C for one hour. Alternatively, the electrochemically exfoliated graphene nano-platelets were collected and redispersed in DMF to form inks. The printed film of conductivity ~2.5^103 S/m was obtained after annealing at 300 °C for one hour.

    Water based GO/Ag hybrid inks were developed for screen printing. When high concentration GO aqueous dispersion was mixed with reactive silver ink, the viscosity of the mixture increased instantly to above 1000 cP as a result of reactions between oxygen functional groups (OFGs) on GO sheets and ingredients in the reactive silver ink. When the screen printed lines with different GO:Ag ratios were annealed in air, the conductivity of the resultant reduced graphene oxide/silver nanoparticles (RGO/AgNPX) composites decreased as silver content increased. As oxygen enriched compounds in RGO/AgNPX composites were detected, we proposed that AgOx compounds were generated on the AgNPs surface, which raised the contact resistance between AgNPs and RGO flakes. To solve this problem, the printed patterns were instead annealed in reducing gas (Ar/H2 5%). The electrical conductivity ~2.0^104 S/m was then achieved.

    Furthermore, the reduction of GO using ammonium formate as reducing reagent was investigated. When applying a hydrothermal method, ammonium formate shows excellent reduction ability, surpassing the widely used reducing agent, L-ascorbic acid, under same condition. Elemental analysis shows the C/O ratio of RGO as high as ~11 and most OFGs were removed in the reduction process. Meanwhile, incorporated nitrogen atoms introduced active sites in resultant RGO, making it a promising electrocatalyst for oxygen reduction reaction.

    Delarbeten
    1. Scalable inkjet printing of shear-exfoliated graphene transparent conductive films
    Öppna denna publikation i ny flik eller fönster >>Scalable inkjet printing of shear-exfoliated graphene transparent conductive films
    2016 (Engelska)Ingår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 102, s. 51-57Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this study, we demonstrate scalable and efficient inkjet printing of graphene flexible transparent conducting films (TCFs). The highly concentrated and stable graphene ink (3.2 mg/mL) that is dominated by 4-layer graphene flakes is achieved by means of shear exfoliation process. The printed graphene TCFs with DC conductivity of ∼4 × 104 S/m (sheet resistance 260 Ω/□ coupled with optical transparency of 86%) without intentional doping are readily obtained. Excellent flexibility and air stability of the printed graphene TCFs allow their potential applications in different flexible opto-electronics devices. Systematic investigation of the inkjet printing of graphene and the annealing effect on the graphene TCFs is presented.

    Nyckelord
    Graphene, Inkjet printing, Transparent conductive films
    Nationell ämneskategori
    Den kondenserade materiens fysik Teknik och teknologier
    Identifikatorer
    urn:nbn:se:uu:diva-276479 (URN)10.1016/j.carbon.2016.02.013 (DOI)000372808200006 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), Dnr SE13-0061Vetenskapsrådet, 621-2014-5596
    Tillgänglig från: 2016-02-14 Skapad: 2016-02-14 Senast uppdaterad: 2019-02-25Bibliografiskt granskad
    2. Inkjet printing of electrochemically-exfoliated graphene nano-platelets
    Öppna denna publikation i ny flik eller fönster >>Inkjet printing of electrochemically-exfoliated graphene nano-platelets
    Visa övriga...
    2016 (Engelska)Ingår i: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 220, s. 318-322Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this study, we report on a facile method of inkjet printing of graphene nano-platelets (GNPs). The GNPs are exfoliated from graphite by means of an electrochemical process in an inorganic salt based electrolyte. The electrochemically exfoliated GNPs with oxygen-bearing functional groups exhibit spectroscopic features similar to those of reduced graphene oxides. As a result, ink formulation with such GNPs for inkjet printing readily accomplishes without using stabilizer and various conductive objects are easily fabricated on different substrates by inkjet printing. The as-printed films of the electrochemically exfoliated GNPs deliver an electrical conductivity of 44 S/m, a typical value for as-printed pristine GNP films in the literature. A simple thermal treatment results in an improved DC conductivity by two orders of magnitude to ~2.5 × 103 S/m.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2016
    Nyckelord
    Graphene; Electrochemical process; Inkjet printing
    Nationell ämneskategori
    Annan materialteknik
    Identifikatorer
    urn:nbn:se:uu:diva-298103 (URN)10.1016/j.synthmet.2016.06.029 (DOI)000383811300040 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), Dnr SE13-0061Vetenskapsrådet, 621-2014-5596
    Tillgänglig från: 2016-06-29 Skapad: 2016-06-29 Senast uppdaterad: 2019-02-25Bibliografiskt granskad
    3. Screen Printed Conductive Composites with Reduced Graphene Oxide and Silver
    Öppna denna publikation i ny flik eller fönster >>Screen Printed Conductive Composites with Reduced Graphene Oxide and Silver
    2018 (Engelska)Ingår i: 2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac), 2018, s. 35-39Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This work provides a method to fabricate conductive composites by screen printing of aqueous hybrid inks with graphene oxide (GO) and silver acetate as silver source. The formulation of the aqueous hybrid inks is realized by mixing highly concentrated GO solution and reactive silver solution, which readily results in a formation of viscous pastes. Composite films with four-probe structure were fabricated by means of blade coating, followed by annealing at 160 °C in air and subsequently at 600 °C in Ar/H 2 . While the reactive silver solution without GO can be completely reduced when annealed at 90 °C in air, resulting in elemental Ag films with resistivity close to the bulk value, no reduction occurs in the hybrid inks under the same annealing condition. Silver nanoparticles are formed from the hybrid inks at 160 °C and discretely distributed on the reduced GOs (rGOs), which shows a retardation effect of GO on the reduction of silver. Further annealing at 600 °C in Ar/H 2 leads to partial restoration of sp 2 lattice in the rGOs. The resistivity of the composite films increases as the silver content is increased, which is interpreted by using a percolation model with rGO networks.

    Nyckelord
    annealing, coatings, electrical conductivity, electrical resistivity, graphene compounds, mixing, nanocomposites, nanofabrication, nanoparticles, percolation, reduction (chemical), silver, thin films, aqueous hybrid inks, silver acetate, reactive silver solution, silver nanoparticles, reduced graphene oxide, screen printed conductive composites, viscous pastes, four-probe structure, blade coating, retardation effect, percolation model, temperature 160.0 degC, temperature 600.0 degC, temperature 90.0 degC, CO-Ag, Ink, Films, Conductivity, Printing, Graphene, graphene oxide, conductive composite, screen printing
    Nationell ämneskategori
    Materialkemi
    Identifikatorer
    urn:nbn:se:uu:diva-363974 (URN)10.23919/NORDPAC.2018.8423856 (DOI)
    Konferens
    2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac), 12th – 14th June 2018, Oulu, Finland
    Forskningsfinansiär
    Vetenskapsrådet, No. 621-2014-5596Stiftelsen för strategisk forskning (SSF), Dnr SE13-0061
    Tillgänglig från: 2018-10-22 Skapad: 2018-10-22 Senast uppdaterad: 2019-03-14Bibliografiskt granskad
    4. Efficient Gelation of Graphene Oxide Aqueous Dispersion Induced by Sonication-Promoted Leuckart Reaction
    Öppna denna publikation i ny flik eller fönster >>Efficient Gelation of Graphene Oxide Aqueous Dispersion Induced by Sonication-Promoted Leuckart Reaction
    Visa övriga...
    2018 (Engelska)Ingår i: ChemNanoMat, ISSN 2199-692X, Vol. 4, nr 11, s. 1145-1152Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Abstract Graphene oxide (GO) undergoes a rapid gelation process in the presence of ammonium hydroxide and formic acid at room temperature which is promoted by ultrasonication. Infrared and X-ray photoelectron spectroscopy proved partial reduction of GO and nitrogen incorporation, resulting from sonication-promoted Leuckart reactions at GO carbonyl groups. The amine groups produced via Leuckart reactions undergo further reactions that result in salt bridges with carboxylic groups and covalent cross-links, both of which contribute to the stabilization of the resulting hydrogel. The resultant GO hydrogel exhibits enhanced thermal stability.

    Nyckelord
    Gelation, graphene oxide, hydrogels, Leuckart reaction, ultrasonication
    Nationell ämneskategori
    Materialteknik
    Identifikatorer
    urn:nbn:se:uu:diva-363972 (URN)10.1002/cnma.201800286 (DOI)000452398900006 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), SE13-0061Vetenskapsrådet, No. 621-2014-5596Knut och Alice Wallenbergs Stiftelse
    Tillgänglig från: 2018-10-22 Skapad: 2018-10-22 Senast uppdaterad: 2019-02-25
    5. Nitrogen-doped Reduced Graphene Oxide Hydrogel Achieved via a One-Step Hydrothermal Process
    Öppna denna publikation i ny flik eller fönster >>Nitrogen-doped Reduced Graphene Oxide Hydrogel Achieved via a One-Step Hydrothermal Process
    Visa övriga...
    2019 (Engelska)Ingår i: CHEMNANOMAT, ISSN 2199-692X, Vol. 5, nr 9, s. 1144-1151Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We report an efficient one-step method to achieve highly reduced graphene oxide (rGO) hydrogel doped with nitrogen where the rGO sheets are interconnected forming a porous structure by means of hydrothermal process. During the synthesis, ammonium formate is used as reducing reagent and simultaneously as nitrogen supplier, which delivers nitrogen-doped rGO (NRGO) hydrogel that exhibits C/O atomic ratio as high as at ~11.1 and contains decent ~5.4 at.% nitrogen. As comparison, the reduction efficiency is only half of the value and no nitrogen doping can be obtained when L-ascorbic acid is used as reducing reagent. The resultant NRGO shows enhanced electrocatalytic ability for oxygen reduced reaction indicating its great potential of the one-step method for the catalyst and energy applications. 

    Ort, förlag, år, upplaga, sidor
    WILEY-V C H VERLAG GMBH, 2019
    Nyckelord
    reduced graphene oxide, ammonium formate, hydrothermal, reduction, oxygen reduction reaction
    Nationell ämneskategori
    Teknik och teknologier
    Forskningsämne
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-377624 (URN)10.1002/cnma.201900167 (DOI)000476035600001 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF), Dnr SE13-0061Vetenskapsrådet, 621-2014-5596
    Tillgänglig från: 2019-02-22 Skapad: 2019-02-22 Senast uppdaterad: 2019-11-04Bibliografiskt granskad
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  • 86.
    Song, Man
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhao, Jie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Meng, Yu
    Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Hou, Peng-Xiang
    Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.
    Grennberg, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Zhang, Zhi-Bin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Nitrogen-doped Reduced Graphene Oxide Hydrogel Achieved via a One-Step Hydrothermal Process2019Ingår i: CHEMNANOMAT, ISSN 2199-692X, Vol. 5, nr 9, s. 1144-1151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report an efficient one-step method to achieve highly reduced graphene oxide (rGO) hydrogel doped with nitrogen where the rGO sheets are interconnected forming a porous structure by means of hydrothermal process. During the synthesis, ammonium formate is used as reducing reagent and simultaneously as nitrogen supplier, which delivers nitrogen-doped rGO (NRGO) hydrogel that exhibits C/O atomic ratio as high as at ~11.1 and contains decent ~5.4 at.% nitrogen. As comparison, the reduction efficiency is only half of the value and no nitrogen doping can be obtained when L-ascorbic acid is used as reducing reagent. The resultant NRGO shows enhanced electrocatalytic ability for oxygen reduced reaction indicating its great potential of the one-step method for the catalyst and energy applications. 

  • 87.
    Bose, Sourav
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.
    Cunha, J. M. V.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    Borme, J.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.
    Chen, Wei-Chao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Shariati Nilsson, Nina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Teixeira, J. P.
    Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    Gaspar, J.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.
    Leitao, J. P.
    Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Fernandes, P. A.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal;Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal;Inst Politecn Porto, Inst Super Engn Porto, Dept Fis, Rua Dr Antonio Bernardino de Almeida 431, P-4200072 Porto, Portugal.
    Salome, P. M. P.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    A morphological and electronic study of ultrathin rear passivated Cu(In,Ga)Se2 solar cells2019Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 671, s. 77-84Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of introducing a passivation layer at the rear of ultrathin Copper Indium Gallium di-Selenide Cu(In,Ga)Se2 (CIGS) solar cells is studied. Point contact structures have been created on 25 nm Al2O3 layer using e-beam lithography. Reference solar cells with ultrathin CIGS layers provide devices with average values of light to power conversion efficiency of 8.1% while for passivated cells values reached 9.5%. Electronic properties of passivated cells have been studied before, but the influence of growing the CIGS on Al2O3 with point contacts was still unknown from a structural and morphological point of view. Scanning Electron Microscopy, X-ray Diffraction and Raman spectroscopy measurements were performed. These measurements revealed no significant morphological or structural differences in the CIGS layer for the passivated samples compared with reference samples. These results are in agreement with the similar values of carrier density (~8 x 1016 cm-3) and depletion region (~160 nm) extracted using electrical measurements. A detailed comparison between both sample types in terms of current-voltage, external quantum efficiency and photoluminescence measurements show very different optoelectronic behaviour which is indicative of a successful passivation. SCAPS simulations are done to explain the observed results in view of passivation of the rear interface.

    Publikationen är tillgänglig i fulltext från 2020-12-16 00:00
  • 88.
    Sortica, Mauricio A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Paneta, Valentina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Bruckner, Barbara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik. Johannes Kepler Univ Linz, Atom Phys & Surface, A-4040 Linz, Austria.
    Lohmann, Svenja
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Nyberg, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Bauer, Peter
    Johannes Kepler Univ Linz, Atom Phys & Surface, A-4040 Linz, Austria.
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    On the Z(1)-dependence of electronic stopping in TiN2019Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikel-id 176Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a thorough experimental study of electronic stopping of H, He, B, N, Ne and Al ions in TiN with the aim to learn about the energy loss mechanisms of slow ions. The energy loss was measured by means of time-of-flight medium-energy ion scattering. Thin films of TiN on silicon with a delta-layer of W at the TiN/Si interface were used as targets. We compare our results to non-linear density functional theory calculations, examining electron-hole pair excitations by screened ions in a free electron gas in the static limit, with a density equivalent to the expected value for TiN. These calculations predict oscillations in the electronic stopping power for increasing atomic number Z(1) of the projectile. An increasing discrepancy between our experimental results and predictions by theory for increasing Z(1) was observed. This observation can be attributed to contributions from energy loss channels different from electron-hole pair excitation in binary Coulomb collisions.

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  • 89.
    Johansson Byberg, Joel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    A comparative study of ZnO i-layer deposited with ALD and PVD for CIGS solar cells2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Two identified setbacks for CIGS based devices in order to obtain higher efficiency

    are parasitic absorption in the window layer structure and losses in open-circuit

    voltage due to bad interfaces. This study investigated how the performance of the

    solar cell is affected by depositing intrinsic ZnO (i-ZnO) and ZnMgO with atomic

    layer deposition (ALD) instead of the conventional sputtering.

    No significant improvement in fill factor was obtained by the use of ALD compared

    to sputtering, leading to the conclusion that pinholes in the sputtered film are not a

    detrimental factor for the cell. As the thickness of the i-layer increased, an

    increase in FF was observed for the ALD-deposited i-layer, whereas a decrease

    was observed for the sputtered i-layer. The open-circuit voltage was considered

    constant between the two series with only small fluctuations, indicating that the

    defect chemistry of the i-ZnO/CdS interface was not improved with the use of ALD.

    In this study it is shown that a gain in short-circuit current can be obtained for

    CIGS solar cells in the high energy region of the spectrum by reducing the

    thickness of the i-ZnO, as well as alloying the ZnO with Mg. When compared with a

    baseline layer sample with a sputtered i-layer thickness of around 90 nm, the

    estimated gain in short-circuit current density without a loss in fill factor was 0.14

    and 0.20 mA/cm2 for ALD and sputtering, respectively. For the series with a

    ZnMgO i-layer, the highest estimated gain was 0.17 mA/cm2. This was observed

    for the sample with a 4:1 (Zn:Mg) pulse ratio, whereas higher Mg contents yielded

    a too high band gap that resulted in an electron blocking barrier.

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  • 90.
    Chen, Xi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Chen, Si
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Hu, Qitao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Solomon, Paul
    IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Device noise reduction for Silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate2019Ingår i: ACS sensors, ISSN 2379-3694, Vol. 4, nr 2, s. 427-433Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The sensitivity of metal-oxide-semiconductor field-effect transistor (MOSFET) based nanoscale sensors is ultimately limited by noise induced by carrier trapping/detrapping processes at the gate oxide/semiconductor interfaces. We have designed a Schottky junction gated silicon nanowire field-effect transistor (SiNW-SJGFET) sensor, where the Schottky junction replaces the noisy oxide/semiconductor interface. Our sensor exhibits significantly reduced noise, 2.1×10-9 V2µm2/Hz at 1 Hz, compared to reference devices with the oxide/semiconductor interface operated at both inversion and depletion modes. Further improvement can be anticipated by wrapping the nanowire by such a Schottky junction thereby eliminating all oxide/semiconductor interfaces. Hence, a combination of the low-noise SiNW-SJGFET sensor device with a sensing surface of the Nernstian response limit holds promises for future high signal-to-noise ratio sensor applications.

  • 91.
    Igalson, M.
    et al.
    Warsaw Univ Technol, Fac Phys, Koszykowa 75, PL-00662 Warsaw, Poland.
    Maciaszek, M.
    Warsaw Univ Technol, Fac Phys, Koszykowa 75, PL-00662 Warsaw, Poland.
    Macielak, K.
    Warsaw Univ Technol, Fac Phys, Koszykowa 75, PL-00662 Warsaw, Poland.
    Czudek, A.
    Warsaw Univ Technol, Fac Phys, Koszykowa 75, PL-00662 Warsaw, Poland.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Barreau, N.
    Univ Nantes, CNRS, Inst Mat Jean Rouxel IMN, 2 Rue Houssiniere,BP 32229, F-44322 Nantes 3, France.
    Concentration of defects responsible for persistent photoconductivity in Cu (In,Ga)Se-2: Dependence on material composition2019Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 669, s. 600-604Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Persistent photoconductivity (PPC) in thin Cu(In,Ga)Se-2 films is discussed within a model of relaxing defects acting as donors or acceptors depending on their configurational and charge state. The aim of this work is to identify the factors related to technological processes which affect the magnitude of PPC. We established a method of evaluation of the concentration of metastable defects in thin Cu(In,Ga)Se-2 films relating it to the position of the Fermi level in thermodynamic equilibrium and used it to compare and discuss the impact of preparation details on the PPC value. The main result is that deviation from Cu/(Ga + In) stoichiometry does not change the concentration of metastable defects. Post deposition annealing in selenium affects the PPC depending on the presence of sodium during the treatment, while the impact of sodium itself on the metastable defect concentration apparently depends on whether it is present during the Cu(In,Ga)Se-2 deposition process or whether it is supplied during post-deposition treatment.

  • 92.
    Xu, Xingxing
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Makaraviciute, Asta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Pettersson, Jean
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Revisiting the factors influencing gold electrodes prepared using cyclic voltammetry2019Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 283, s. 146-153Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gold is widely used as the electrode material in different chemi- and biosensing applications while cyclic voltammetry (CV) in sulfuric acid solutions is a commonly employed method for gold surface preparation and characterization. However, as shown herein, chloride leakage from the Ag/AgCl/sat. KCl reference electrode and platinum dissolution from the platinum counter electrode can severely compromise the reproducibility and hence the reliability of the prepared gold electrodes. The aim of this work is to obtain a comprehensive understanding of the separate and interdependent effects of the aforementioned factors on the voltammetric behavior of microfabricated polycrystalline gold electrodes. It is shown that the leakage of chloride gives rise to etching of both the gold working and the platinum counter electrodes and that the chloride concentration has a strong influence on the ratio between the obtained gold and platinum concentrations in the electrolyte. The dissolved gold and platinum are then re-deposited on the gold electrode on the cathodic voltammetric scan, changing the structure and properties of the electrode. It is also demonstrated that the changes in the properties of the gold electrode are determined by the ratio between the co-deposited platinum and gold rather than the absolute amount of platinum deposited on the gold electrode. In addition, the chloride and sulfate adsorption behavior on the gold electrode is carefully investigated. It is proposed that redox peaks due to the formation ofthe corresponding Au(I) complexes can be seen in the double layer region of the voltammogram. The results show that the chloride leakage from the reference electrode needs to be carefully controlled and that platinum counter electrodes should be avoided when developing gold sensing electrodes. The present comprehensive understanding of the electrochemical performance of gold electrodes prepared using CV should be of significant importance in conjunction with both fundamental investigations and practical applications.

  • 93.
    Niklasson, Gunnar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Qiu, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Bayrak Pehlivan, Ilknur
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Impedance spectroscopy of water splitting reactions on nanostructured metal-based catalysts2019Ingår i: Functional Materials and Nanotechnologies (FM&NT 2018), Institute of Physics Publishing (IOPP), 2019, artikel-id 012005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hydrogen production by water splitting using nanomaterials as electrocatalysts is a promising route enabling replacement of fossil fuels by renewable energy sources. In particular, the development of inexpensive non-noble metal-based catalysts is necessary in order to replace currently used expensive Pt-based catalysts. We report a detailed impedance spectroscopy study of Ni-Mo and Ni-Fe based electrocatalytic materials deposited onto porous and compact substrates with different conductivities. The results were interpreted by a critical comparison with equivalent circuit models. The reaction resistance displays a strong dependence on potential and a lower substrate dependence. The impedance behaviour can also provide information on the dominating reaction mechanism. An optimized Ni-Fe based catalyst showed very promising properties for applications in water electrolysis.

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  • 94. Zeng, Ruixue
    et al.
    Zhang, Junkai
    Yang, Hui
    Sun, Cuiling
    Xu, Ming
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wu, Dongping
    Modelling and Characterization of Novel Reference-Less Semiconductor Ion Sensor for pH Sensing2019Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 281, s. 60-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A SPICE macromodel is developed for a novel reference-less semiconductor ion sensor (RELESIS), which has been proposed to eliminate the use of reference electrode in the field effect based sensor detection. The working principle of the RELESIS, previously validated by a prototype device via pH sensing, is featured by non-constant bulk solution potential, which distincts itself from any conventional ion sensitive field effect transistor. Simulations are performed here using the macromodel and the results fit well with the experimental data. The proposed SPICE macromodel can be used to predict the behavior of the RELESIS and carry out performance optimizations for the RELESIS to be used in various applications.

  • 95.
    Redzwan, Syaiful
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Velander, Jacob
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Perez, Mauricio D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Asan, Noor Badariah
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Rajabi, Mina
    KTH Royal Inst Technol, Sch Elect Engn, Dept Micro & Nanosyt, Stockholm, Sweden.
    Niklaus, Frank
    KTH Royal Inst Technol, Sch Elect Engn, Dept Micro & Nanosyt, Stockholm, Sweden.
    Nowinski, Daniel
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Plastikkirurgi.
    Lewén, Anders
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Enblad: Neurokirurgi.
    Enblad, Per
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Enblad: Neurokirurgi.
    Augustine, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Initial In-Vitro Trial for Intra-Cranial Pressure Monitoring Using Subdermal Proximity-Coupled Split-Ring Resonator2018Ingår i: Proceedings of the 2018 IEEE/MTT-S International Microwave Biomedical Conference (IMBioC), IEEE, 2018, s. 73-75Konferensbidrag (Refereegranskat)
    Abstract [en]

    Intra cranial pressure (ICP) monitoring is used in treating severe traumatic brain injury (TBI) patients. All current clinical available measurement methods are invasive presenting considerable social costs. This paper presents a preliminary investigation of the feasibility of ICP monitoring using an innovative microwave-based non-invasive approach. A phantom mimicking the dielectric characteristics of human tissues of the upper part of the head at low microwave frequencies is employed together to a proof-of-concept prototype based on the proposed approach consisting in a readout system and a sub-dermally implanted passive device, both based in split ring resonator techniques. This study shows the potential of our approach to detect two opposite pressure variation stages inside the skull. The employed phantom model needs to be improved to support finer variations in the pressure and better phantom parts, principally for the skull mimic and the loss tangent of all mimics.

  • 96.
    Velander, Jacob
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Redzwan, Syaiful
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Perez, Mauricio D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Asan, Noor Badariah
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Nowinski, Daniel
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Plastikkirurgi.
    Lewén, Anders
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Enblad: Neurokirurgi.
    Enblad, Per
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Enblad: Neurokirurgi.
    Augustine, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    A Four-Layer Phantom for Testing In-Vitro Microwave-Based Sensing Approach in Intra-Cranial Pressure Monitoring2018Ingår i: Proceedings Of The 2018 IEEE/MTT-S International Microwave Biomedical Conference (IMBioC), IEEE, 2018, s. 49-51Konferensbidrag (Refereegranskat)
    Abstract [en]

    Multi-layer phantoms in proofs of concept, designs and validations of both microwave-based biomedical sensing and imaging system are becoming popular means to facilitate in-vitro experiments. In addition, they can contribute significantly to reduce animal use in scientific experimentation. In this paper, we design and fabricate a four-layer phantom composed of skin, skull, cerebrospinal fluid and brain mimic tissues to work between 2 and 3 GHz. In addition, the phantom incorporates a mechanism to produce pressure variation between the cerebrospinal fluid and the brain mimic tissues. This phantom is used in an in-vitro experiment to test and validate a new approach which could sense intra-cranial pressure variations through a microwave-based reflection method. The similarity of the phantom's tissues with human tissues from the viewpoint of the microwave response is analyzed in comparison with data from Italian Institute of Applied Physics in Florence. We found good agreement for the dielectric constant (Rel. Err. < 13 % for 68% of significance) in skin, cerebrospinal fluid and brain mimic tissues. For the skin, we got also good agreement for the loss tangent (Rel. Err. < 11 % for 68% of significance). The skull mimic phantom was stiff enough, but even presenting considerable errors, it was still good enough for the experiment. In addition, the capability of the phantom to operate at different pressures is discussed.

  • 97.
    Lee, Doojin
    et al.
    Univ Waterloo, Mech & Mechatron Engn, Waterloo, ON, Canada.
    Shaker, George
    Univ Waterloo, Mech & Mechatron Engn, Waterloo, ON, Canada.
    Nowinski, Daniel
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Plastikkirurgi.
    Augustine, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Monitoring of Healing Progression of Cranial Vault using One-dimensional Pulsed Radar Technique2018Ingår i: Proceedings of the 2018 IEEE/MTT-S International Microwave Biomedical Conference (IMBioC), IEEE, 2018, s. 64-66Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, the skull healing after surgery has been investigated using proposed resistively loaded antenna utilizing the principles of short pulse radar technique. The one-dimensional pulsed profile for every stage has been demonstrated that the healing stages after craniotomy can be monitored by observing the change in the amplitude of the matched filter responses.

  • 98.
    Asan, Noor Badariah
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Velander, Jacob
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Redzwan, Syaiful
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Perez, Mauricio D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Hassan, Emadeldeen
    Umeå University, Department of Computing Science, Umeå, Sweden.
    Blokhuis, Taco J.
    Maastricht University Medical Center, Department of Surgery, Maastricht, The Netherland.
    Voigt, Thiemo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorarkitektur och datorkommunikation.
    Augustine, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Effect of thickness inhomogeneity in fat tissue on in-body microwave propagation2018Ingår i: 2018 IEEE International Microwave Biomedical Conference (IMBioC), Philadelphia, USA: IEEE, 2018, s. 136-138Konferensbidrag (Refereegranskat)
    Abstract [en]

    In recent studies, it has been found that fat tissue can be used as a microwave communication channel. In this article, the effect of thickness inhomogeneities in fat tissues on the performance of in-body microwave communication at 2.45 GHz is investigated using phantom models. We considered two models namely concave and convex geometrical fat distribution to account for the thickness inhomogeneities. The thickness of the fat tissue is varied from 5 mm to 45 mm and the Gap between the transmitter/receiver and the starting and ending of concavity/convexity is varied from 0 mm to 25 mm for a length of 100 mm to study the behavior in the microwave propagation. The phantoms of different geometries, concave and convex, are used in this work to validate the numerical studies. It was noticed that the convex model exhibited higher signal coupling by an amount of 1 dB (simulation) and 2 dB (measurement) compared to the concave model. From the study, it was observed that the signal transmission improves up to 30 mm thick fat and reaches a plateau when the thickness is increased further.

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  • 99.
    Lee, Doojin
    et al.
    UW, Mech & Mechatron Engn, Waterloo, ON, Canada.
    Shaker, George
    UW, Mech & Mechatron Engn, Waterloo, ON, Canada.
    Augustine, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Preliminary Study: Monitoring of Healing Stages of Bone Fracture utilizing UWB Pulsed Radar Technique2018Ingår i: 2018 18th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM 2018), IEEE, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The feasibility study of healing stages after fracture has been performed in this paper. The ultra-wide band (UWB) pulsed radar technique has been applied to monitor the healing stages in the way of numerical approach and simulation study as a proof of concept. The healing stages can be monitored by looking at the changes in amplitude of reflected pulse.

  • 100.
    Quaglia Casal, Luciano
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Developing a Combinatorial Synthesis Database Tool2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Thin-film solar cell research is central to the electricity production of the near future. Photovoltaic technologies based on silicon have a significant portion of the global market and installed capacity. Thin-film solar cells are port of the emerging photovoltaic technologies that are challenging silicon for a part of the electricity production based on solar power. These thin-film technologies, such as copper indium gallium selenide (CIGS) and cadmium telluride (CdTe), are lower cost and require less energy to produce, but also require rare materials. An alternative to these technologies are thin-film solar cells based on more abundant materials. To develop these new materials at Uppsala University, combinatorial synthesis is used. This method produces a significant amount of data across different measurement methods. The data needs to be analysed and combined to gather information about the characteristics of the materials being developed. To facilitate the analysis and combination of data, a database tool was created in MATLAB. The result is a program that allows its User to combine energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy and Photoluminescence spectroscopy measurements done on solar cell absorber layers. Absorber layers are the section of solar cells where sun lighet is absorbed, and electron-hole pairs are created. The program provides multiple figures and graphs combining the different data collected, enabling the User to draw conclusions about the characteristics of the sample and its suitability as an absorber layer. The combinatorial synthesis database tool created could be user for combinatorial synthesis analysis of other material samples that are not necessarily absorber layers for thin-film solar cells. This report describes both the development of the tool and the code itself.

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