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Publications (10 of 90) Show all publications
Chen, X., Chen, S., Hu, Q., Zhang, S.-L., Solomon, P. & Zhang, Z. (2019). Device noise reduction for Silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate. ACS sensors, 4(2), 427-433
Open this publication in new window or tab >>Device noise reduction for Silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate
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2019 (English)In: ACS sensors, ISSN 2379-3694, Vol. 4, no 2, p. 427-433Article in journal (Refereed) 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.

Keywords
Noise reduction, schottky junction gate, silicon nanowire, field-effect transistor, low frequency noise, ion sensor
National Category
Nano Technology Signal Processing
Identifiers
urn:nbn:se:uu:diva-374776 (URN)10.1021/acssensors.8b0139 (DOI)000459836400021 ()30632733 (PubMedID)
Funder
Swedish Foundation for Strategic Research , SSF ICA 12-0047Swedish Foundation for Strategic Research , FFL15-0174Swedish Research Council, VR 2014-5588Knut and Alice Wallenberg Foundation
Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-03-18Bibliographically approved
Xu, X., Makaraviciute, A., Pettersson, J., Zhang, S.-L., Nyholm, L. & Zhang, Z. (2019). Revisiting the factors influencing gold electrodes prepared using cyclic voltammetry. Sensors and actuators. B, Chemical, 283, 146-153
Open this publication in new window or tab >>Revisiting the factors influencing gold electrodes prepared using cyclic voltammetry
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2019 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 283, p. 146-153Article in journal (Refereed) Published
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.

Keywords
gold electrode, cyclic voltammetry, platinum, electrde etching, chloride leakage, Au(I) complexes
National Category
Analytical Chemistry
Research subject
Chemistry with specialization in Inorganic Chemistry; Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-372135 (URN)10.1016/j.snb.2018.12.008 (DOI)000455854000018 ()
Funder
Swedish Foundation for Strategic Research , ICA 12-0047Swedish Foundation for Strategic Research , FFL15-0174Swedish Research Council, 2014-5588Wallenberg Foundations, Academy Fellow
Available from: 2019-01-06 Created: 2019-01-06 Last updated: 2019-02-18Bibliographically approved
Xu, X., Makaraviciute, A., Pettersson, J., Zhang, S.-L. & Zhang, Z. (2018). Considerations for the Cyclic Voltammetry of Gold in Sulfuric Acid Solutions. In: : . Paper presented at 69th Annual Meeting of the International Society of Electrochemistry in Bologna.
Open this publication in new window or tab >>Considerations for the Cyclic Voltammetry of Gold in Sulfuric Acid Solutions
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

A comprehensive understanding of the cyclic voltammetry (CV) for gold surfaces is essential for advanced applications. In the present study, a series of experiments were designed to investigate CV for gold under different experimental conditions when using a conventional configuration of a Ag/AgCl/sat. KCl reference electrode and a platinum wire counter electrode. The interferences introduced by the configuration were reflected in the three fingerprint regions of the voltammograms. It was found that the shape of the voltammograms was less reproducible at a lower sample volume when the cycle number was increased. This observation could be explained by different concentrations of Cl- leaking from the reference electrode and platinum dissolved from the counter electrode. The reproducibility of the gold oxidation and reduction (Ox/Re) region in the voltammograms was improved when gold dissolution and re-deposition caused by Cl- leakage was eliminated by using a bridge. In the hydrogen evolution and oxidation reactions (HER/HOR) region the catalytic performance of the gold electrode could be minimized by replacing the platinum counter electrode with a graphite rod. Alternatively, it could be enhanced by increasing the surface ratio of the co-deposited platinum to gold. In the electric double layer (EDL) region, peaks dependent on the concentrations of Cl- and SO42- were observed. To account for the occurrence of these peaks, a new mechanism based on the formation of neutral gold (I) complexes at very low Au+ concentrations, was proposed. 

National Category
Physical Chemistry Other Chemical Engineering
Identifiers
urn:nbn:se:uu:diva-363362 (URN)
Conference
69th Annual Meeting of the International Society of Electrochemistry in Bologna
Available from: 2018-10-17 Created: 2018-10-17 Last updated: 2018-10-18Bibliographically approved
Hu, Q., Chen, X., Norström, H., Zeng, S., Yifei, L., Fredrik, G., . . . Zhang, Z. (2018). Current gain and low-frequency noise of symmetriclateral bipolar junction transistors on SOI. In: : . Paper presented at 48th European Solid-State Device Research Conference, September 3 - 6, 2018, Dresden, Germany.
Open this publication in new window or tab >>Current gain and low-frequency noise of symmetriclateral bipolar junction transistors on SOI
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2018 (English)Conference paper, Published paper (Refereed)
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.

Keywords
symmetric lateral bipolar junction transitor; current amplification; low frequency noise; silicon nanowire field-effect transitor
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-364155 (URN)
Conference
48th European Solid-State Device Research Conference, September 3 - 6, 2018, Dresden, Germany
Note

Qitao Hu and Xi Chen contribute equally to the work.

Available from: 2018-10-24 Created: 2018-10-24 Last updated: 2019-03-06Bibliographically approved
Wen, C., Zeng, S., Zhang, Z. & Zhang, S.-L. (2018). Group behavior of nanoparticles translocating multiple nanopores. Analytical Chemistry, 90(22), 13483-13490
Open this publication in new window or tab >>Group behavior of nanoparticles translocating multiple nanopores
2018 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 90, no 22, p. 13483-13490Article in journal (Refereed) 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.

Place, publisher, year, edition, pages
Washington: American Chemical Society (ACS), 2018
National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-369418 (URN)10.1021/acs.analchem.8b03408 (DOI)000451246100048 ()30372031 (PubMedID)
Funder
Swedish Research Council, 621-2014-6300Stiftelsen Olle Engkvist Byggmästare, 2016/39
Available from: 2018-12-13 Created: 2018-12-13 Last updated: 2019-01-24Bibliographically approved
Jablonka, L., Riekehr, L., Zhang, Z., Zhang, S.-L. & Kubart, T. (2018). Highly conductive ultrathin Co films by high-power impulse magnetron sputtering. Applied Physics Letters, 112(4), Article ID 043103.
Open this publication in new window or tab >>Highly conductive ultrathin Co films by high-power impulse magnetron sputtering
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2018 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 4, article id 043103Article in journal (Refereed) 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.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2018
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-340315 (URN)10.1063/1.5011109 (DOI)000423724300039 ()
Funder
Swedish Foundation for Strategic Research , SE13-0033Swedish Foundation for Strategic Research , RIF14-0053Swedish Research Council, C0514401
Available from: 2018-01-29 Created: 2018-01-29 Last updated: 2018-04-04Bibliographically approved
Jablonka, L., Kubart, T., Gustavsson, F., Descoins, M., Mangelinck, D., Zhang, S.-L. & Zhang, Z. (2018). Improving the morphological stability of nickel germanide by tantalum and tungsten additions. Applied Physics Letters, 112(10)
Open this publication in new window or tab >>Improving the morphological stability of nickel germanide by tantalum and tungsten additions
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2018 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 10Article in journal (Refereed) 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.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-344676 (URN)10.1063/1.5019440 (DOI)
Funder
Swedish Foundation for Strategic Research , SE13- 0033Swedish Foundation for Strategic Research , RIF14- 0053Swedish Research Council, C0514401
Available from: 2018-03-07 Created: 2018-03-07 Last updated: 2018-05-18Bibliographically approved
Zhang, D., Solomon, P., Zhang, S.-L. & Zhang, Z. (2018). Low-frequency noise originating from the dynamic hydrogen ion reactivity at the solid/liquid interface of ion sensors. In: : . Paper presented at China Semiconductor Technology International Conference (CSTIC).
Open this publication in new window or tab >>Low-frequency noise originating from the dynamic hydrogen ion reactivity at the solid/liquid interface of ion sensors
2018 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

Low-frequency noise (LFN) is of significant implications in ion sensing. As a primary component of LFN for ion sensing in electrolytes, the solid/liquid interfacial noise remains poorly explored especially regarding its relation to the surface binding/de-binding dynamic properties. In this talk, the solid/liquid interfacial noise will first be characterized by direct electrical measurements. It will then be correlated to the dynamic properties of surface protonation (i.e., hydrogen binding) and deprotonation (i.e., hydrogen de-binding) processes using an impedance spectroscopy. Finally we will provide insights into how detailed surface properties may affect the noise performance of an ion sensor operating in electrolytes.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-347580 (URN)
Conference
China Semiconductor Technology International Conference (CSTIC)
Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-09
Chen, X., Hu, Q., Chen, S., Netzer, N. L., Wang, Z., Zhang, S.-L. & Zhang, Z. (2018). Multiplexed analysis of molecular and elemental ions using nanowire transistor sensors. Sensors and actuators. B, Chemical, 270, 89-96
Open this publication in new window or tab >>Multiplexed analysis of molecular and elemental ions using nanowire transistor sensors
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2018 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 270, p. 89-96Article in journal (Refereed) 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.

Keywords
Elemental ion, ISFET, Metal-organic supercontainer, Molecular ion, Multiplex detection, Silicon nanowire FET
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-351716 (URN)10.1016/j.snb.2018.05.018 (DOI)000434011500011 ()
Funder
Swedish Foundation for Strategic Research , SSF ICA 12-0047;FFL15-0174Swedish Research Council, VR 2014-5588Göran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of Technology, GG 1459BCarl Tryggers foundation , CTS14-527
Note

Xi Chen and Qitao Hu contributed equally to this work

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-08-31Bibliographically approved
Wu, J., Mahajan, A., Riekehr, L., Zhang, H., Yang, B., Meng, N., . . . Yan, H. (2018). Perovskite Sr-x(Bi1-xNa0.97-xLi0.03)(0.5)TiO3 ceramics with polar nano regions for high power energy storage. Nano Energy, 50, 723-732
Open this publication in new window or tab >>Perovskite Sr-x(Bi1-xNa0.97-xLi0.03)(0.5)TiO3 ceramics with polar nano regions for high power energy storage
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2018 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 50, p. 723-732Article in journal (Refereed) Published
Abstract [en]

Dielectric capacitors are very attractive for high power energy storage. However, the low energy density of these capacitors, which is mainly limited by the dielectric materials, is still the bottleneck for their applications. In this work, lead-free single-phase perovskite Srx(Bi1-xNa0.97-xLi0.03)(0.5)TiO3 (x = 0.30 and 0.38) bulk ceramics, prepared using solid-state reaction method, were carefully studied for the dielectric capacitor application. Polar nano regions (PNRs) were created in this material using co-substitution at A-site to enable relaxor behaviour with low remnant polarization (P-r) and high maximum polarization (P-max). Moreover, P-max was further increased due to the electric field induced reversible phase transitions in nano regions. Comprehensive structural and electrical studies were performed to confirm the PNRs and reversible phase transitions. And finally a high energy density (1.70 J/cm(3)) with an excellent efficiency (87.2%) was achieved using the contribution of field-induced rotations of PNRs and PNR-related reversible transitions in this material, making it among the best performing lead-free dielectric ceramic bulk material for high energy storage.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Relaxor Ferroelectric, Dielectric, Polar Nano Regions, Energy Storage
National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-361041 (URN)10.1016/j.nanoen.2018.06.016 (DOI)000438076200084 ()
Funder
Swedish Foundation for Strategic Research , FFL15-0174
Available from: 2018-09-21 Created: 2018-09-21 Last updated: 2018-10-09Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-4317-9701

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