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  • 1.
    Avdeev, M. V.
    et al.
    Joint Inst Nucl Res, Frank Lab Neutron Phys, Dubna 141980, Moscow Reg, Russia..
    Petrenko, V. I.
    Joint Inst Nucl Res, Frank Lab Neutron Phys, Dubna 141980, Moscow Reg, Russia.;Kyiv Taras Shevchenko Natl Univ, Kiev, Ukraine..
    Gapon, I. V.
    Joint Inst Nucl Res, Frank Lab Neutron Phys, Dubna 141980, Moscow Reg, Russia.;Kyiv Taras Shevchenko Natl Univ, Kiev, Ukraine..
    Bulavin, L. A.
    Kyiv Taras Shevchenko Natl Univ, Kiev, Ukraine..
    Vorobiev, Alexey A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Soltwedel, O.
    Max Planck Inst Solid State Res, Outstn MLZ, Garching, Germany..
    Balasoiu, M.
    Joint Inst Nucl Res, Frank Lab Neutron Phys, Dubna 141980, Moscow Reg, Russia.;Natl Inst Phys & Nucl Engn, Bucharest, Romania..
    Vekas, L.
    Acad Romana, Ctr Fundamental & Adv Tech Res, Timisoara Branch, Timisoara, Romania..
    Zavisova, V.
    SAS, Inst Expt Phys, Kosice, Slovakia..
    Kopcansky, P.
    SAS, Inst Expt Phys, Kosice, Slovakia..
    Comparative structure analysis of magnetic fluids at interface with silicon by neutron reflectometry2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 352, p. 49-53Article in journal (Refereed)
    Abstract [en]

    The adsorption of surfactant coated magnetic nanoparticles from highly stable magnetic fluids on crystalline functionalized silicon is studied by neutron reflectometry. Two types of magnetic fluids based on nanomagnetite dispersed and stabilized in non-polar organic solvent (deuterated benzene) and strongly polar solvent (heavy water) are considered. In both cases the interface shows the formation of just one well-defined adsorption layer of nanoparticles, which is insensitive to the effect of the external magnetic field. Still, the particle concentration in the benzene-based fluid is higher in the vicinity to the silicon surface as compared to the bulk distribution. Despite the presence of an aggregate fraction in the water-based system the width of the adsorption layer is consistent with the size of separated particles, thus showing the preferable adsorption of non-aggregated particles.

  • 2. Bandyopadhyay, Sulalit
    et al.
    Singh, Gurvinder
    Sandvig, Ioanna
    Sandvig, Axel
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kumar Puri, Anil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Glomm, Wilhelm Robert
    Synthesis and in vitro cellular interactions of superparamagnetic iron nanoparticles with a crystalline gold shell2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 316, p. 171-178Article in journal (Refereed)
    Abstract [en]

    Fe@Au core-shell nanoparticles (NPs) exhibit multiple functionalities enabling their effective use in applications such as medical imaging and drug delivery. In this work, a novel synthetic method was developed and optimized for the synthesis of highly stable, monodisperse Fe@Au NPs of average diameter similar to 24 nm exhibiting magneto-plasmonic characteristics. Fe@Au NPs were characterized by a wide range of experimental techniques, including scanning (transmission) electron microscopy (S(T)EM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) and UV-vis spectroscopy. The formed particles comprise an amorphous iron core with a crystalline Au shell of tunable thickness, and retain the superparamagnetic properties at room temperature after formation of a crystalline Au shell. After surface modification, PEGylated Fe@Au NPs were used for in vitro studies on olfactory ensheathing cells (OECs) and human neural stem cells (hNSCs). No adverse effects of the Fe@Au particles were observed post-labeling, both cell types retaining normal morphology, viability, proliferation, and motility. It can be concluded that no appreciable toxic effects on both cell types, coupled with multifunctionality and chemical stability make them ideal candidates for therapeutic as well as diagnostic applications.

  • 3.
    Bellardita, Marianna
    et al.
    Univ Palermo, Schiavello Grillone Photocatalysis Grp, Engn Dept, Viale Sci, I-90128 Palermo, Italy.
    Garlisi, Corrado
    Khalifa Univ Sci & Technol, Dept Chem Engn, POB 127788, Abu Dhabi, U Arab Emirates;Khalifa Univ Sci & Technol, Res & Innovat CO2 & H2 RICH Ctr, POB 127788, Abu Dhabi, U Arab Emirates;Khalifa Univ Sci & Technol, Ctr Membrane & Adv Water Technol, POB 135125, Abu Dhabi, U Arab Emirates.
    Ozer, Lütfiye Yildiz
    Khalifa Univ Sci & Technol, Dept Chem Engn, POB 127788, Abu Dhabi, U Arab Emirates;Khalifa Univ Sci & Technol, Res & Innovat CO2 & H2 RICH Ctr, POB 127788, Abu Dhabi, U Arab Emirates;Khalifa Univ Sci & Technol, Ctr Membrane & Adv Water Technol, POB 135125, Abu Dhabi, U Arab Emirates.
    Venezia, Anna Maria
    ISMN CNR, Via Ugo Malfa 153, I-90146 Palermo, Italy.
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Mamedov, Fikret
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Palmisano, Leonardo
    Univ Palermo, Schiavello Grillone Photocatalysis Grp, Engn Dept, Viale Sci, I-90128 Palermo, Italy.
    Palmisano, Giovanni
    Khalifa Univ Sci & Technol, Dept Chem Engn, POB 127788, Abu Dhabi, U Arab Emirates;Khalifa Univ Sci & Technol, Res & Innovat CO2 & H2 RICH Ctr, POB 127788, Abu Dhabi, U Arab Emirates;Khalifa Univ Sci & Technol, Ctr Membrane & Adv Water Technol, POB 135125, Abu Dhabi, U Arab Emirates.
    Highly stable defective TiO2-x with tuned exposed facets induced by fluorine: Impact of surface and bulk properties on selective UV/visible alcohol photo-oxidation2020In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 510, article id 145419Article in journal (Refereed)
    Abstract [en]

    Titanium dioxide samples were prepared in the presence of different amounts of fluorine via hydrothermal method. It has been found that the presence of fluoride influenced the physico-chemical properties of TiO2 in various ways as polymorphic form stability, surface hydroxylation, generation of hydroxyl radicals under irradiation and formation of Ti3+ centers and oxygen vacancies. The generation rate of (OH)-O-center dot radicals was investigated by the photoluminescence technique in the presence of terephthalic acid. X-ray diffractometry indicated that fluorine stabilized the anatase TiO2. X-Ray photoelectron spectroscopy (XPS) revealed the presence of fluorine on the surface and the shift of the valence band edge towards less negative potentials, electron paramagnetic resonance (EPR) confirmed the formation of Ti3+ in the bulk of the photocatalysts, UV-vis spectra showed the extension of the TiO2 photo-response in the visible light region. 2-Propanol degradation and 4-methoxybenzyl alcohol partial oxidation were studied as probe reactions by using the home prepared powders as photocatalysts. Surprisingly, the photocatalytic activity resulted to be mainly affected by (OH)-O-center dot radicals formation ability under irradiation, rather than by the presence of {0 0 1} facets, although it cannot be excluded that the latter could influence the ability to form radicals under irradiation.

  • 4.
    Berner, Simon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Lidbaum, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ledung, G.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Schiessling, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Gelius, Ulrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Bäckwall, J. E.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Oscarsson, Sven
    Electronic and structural studies of immobilized thiol-derivatized cobalt porphyrins on gold surfaces2007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 253, no 18, p. 7540-7548Article in journal (Refereed)
    Abstract [en]

    The immobilisation of thiol-derivatized cobalt porphyrins on gold surfaces has been studied in detail by means of combined scanning tunnelling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). S-thioacetyl has been used as a protective group for the thiol. Different routes for deprotection of the acetyl groups were performed in acidic and in basic conditions. The results show the formation of monolayer films for the different preparation schemes. The immobilisation of the molecules on the gold surface takes place through the thiol-linkers by the formation of multiple thiolate bonds. In the case of layers formed with protected porphyrins approximately 60% of the linkers are bonded to the gold surface whereas for deprotected layers the amount of bonded linkers is increased up to about 80%. STM measurements revealed that the molecules arrange in a disordered overlayer and do not exhibit mobility on the gold surface. Annealing experiments have been performed in order to test the stability of the porphyrin layers. Disordered patterns have been observed in the STM images after annealing at T = 400 °C. XPS revealed that the sulphur content disappeared completely after annealing at T = 180 °C and that the molecules did undergo significant modifications.

  • 5.
    Bhojani, Amit K.
    et al.
    Inst Infrastructure Technol Res & Management IITRA, Dept Basic Sci, Ahmadabad 380026, Gujarat, India..
    Kagdada, Hardik L.
    Inst Infrastructure Technol Res & Management IITRA, Dept Basic Sci, Ahmadabad 380026, Gujarat, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Indian Inst Technol Ropar, Dept Phys, Rupnagar 140001, Punjab, India..
    Singh, Dheeraj K.
    Inst Infrastructure Technol Res & Management IITRA, Dept Basic Sci, Ahmadabad 380026, Gujarat, India..
    Carbon-based monochalcogenides for efficient solar and heat energy harvesting2023In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 608, article id 155121Article in journal (Refereed)
    Abstract [en]

    A new generation of two-dimensional (2D) material has captivated significant attention in the energy conversion field owing to their promising optoelectronics and thermoelectric applications. The present work involves the systematic investigation of fundamental properties of single-layered 2D carbon-based monochalcogenides (CS, CSe, CTe) with planar, buckled and puckered geometry within the framework of density functional theory (DFT). The structural and lattice dynamics analysis disclose that puckered and buckled configurations are energetically and dynamically stable whereas planar structures depict instability. The anisotropic group velocity of longitu-dinal acoustic (LA) and transverse acoustic (TA) phonon modes in puckered systems may render the charac-teristics thermal transport properties. Additionally, for the first time, we scrutinized the thermoelectric and optical properties of these materials. At room temperature, the electron carrier mobilities are 174.698 and 160.830 m(2)V(-1)s(-1) of puckered and buckled CS systems, respectively are highest among all structures. The computed Seebeck coefficient, electrical conductivity and power factor manifests the high thermoelectric transport properties of puckered CS material. Further, the calculated solar parameters demonstrate an excep-tionally high-power conversion efficiency of 19.61 % for puckered CTe. Present work indicates that puckered phase of CS and CTe show their potential for the heat and solar energy harvesting devices, respectively.

  • 6.
    Borges, J.
    et al.
    Czech Tech Univ, Fac Elect Engn, Dept Control Engn, Tech 2, CR-16635 Prague 6, Czech Republic..
    Rodrigues, M. S.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal.;Inst Pedro Nunes, Lab Ensaios Desgaste & Mat, P-3030199 Coimbra, Portugal..
    Lopes, C.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal..
    Costa, D.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal..
    Couto, F. M.
    Norte Fluminense State Univ, Phys Sci Lab, BR-28013602 Campos, RJ, Brazil..
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Martins, B.
    Inst Pedro Nunes, Lab Ensaios Desgaste & Mat, P-3030199 Coimbra, Portugal..
    Duarte, N.
    Inst Pedro Nunes, Lab Ensaios Desgaste & Mat, P-3030199 Coimbra, Portugal..
    Dias, J. P.
    Inst Pedro Nunes, Lab Ensaios Desgaste & Mat, P-3030199 Coimbra, Portugal..
    Cavaleiro, A.
    Univ Coimbra, Dept Mech Engn, SEG CEMUC, P-3030788 Coimbra, Portugal..
    Polcar, T.
    Czech Tech Univ, Fac Elect Engn, Dept Control Engn, Tech 2, CR-16635 Prague 6, Czech Republic.;Univ Southampton, Natl Ctr Adv Tribol Southampton, Southampton SO17 1BJ, Hants, England..
    Macedo, F.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal..
    Vaz, F.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal..
    Thin films composed of Ag nanoclusters dispersed in TiO2: Influence of composition and thermal annealing on the microstructure and physical responses2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 358, p. 595-604Article in journal (Refereed)
    Abstract [en]

    Noble metal powders containing gold and silver have been used for many centuries, providing different colours in the windows of the medieval cathedrals and in ancient Roman glasses. Nowadays, the interest in nanocomposite materials containing noble nanoparticles embedded in dielectric matrices is related with their potential use for a wide range of advanced technological applications. They have been proposed for environmental and biological sensing, tailoring colour of functional coatings, or for surface enhanced Raman spectroscopy. Most of these applications rely on the so-called localised surface plasmon resonance absorption, which is governed by the type of the noble metal nanoparticles, their distribution, size and shape and as well as of the dielectric characteristics of the host matrix. The aim of this work is to study the influence of the composition and thermal annealing on the morphological and structural changes of thin films composed of Ag metal clusters embedded in a dielectric TiO2 matrix. Since changes in size, shape and distribution of the clusters are fundamental parameters for tailoring the properties of plasmonic materials, a set of films with different Ag concentrations was prepared. The optical properties and the thermal behaviour of the films were correlated with the structural and morphological changes promoted by annealing. The films were deposited by DC magnetron sputtering and in order to promote the clustering of the Ag nanoparticles the as-deposited samples were subjected to an in-air annealing protocol. It was demonstrated that the clustering of metallic Ag affects the optical response spectrum and the thermal behaviour of the films.

  • 7.
    Brohede, Ulrika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhao, Shuxi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lindberg, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Forsgren, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    A novel graded bioactive high adhesion implant coating2009In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 255, no 17, p. 7723-7728Article in journal (Refereed)
    Abstract [en]

     One method to increase the clinical success rate of metal implants is to increase their bone bonding properties, i.e. to develop a bone   bioactive surface leading to reduced risks of interfacial problems.   Much research has been devoted to modifying the surface of metals to   make them become bioactive. Many of the proposed methods include   depositing a coating on the implant. However, there is a risk of coating failure due to low substrate adhesion. This paper describes a method to obtain bioactivity combined with a high coating adhesion via   a gradient structure of the coating. Gradient coatings were deposited   on Ti (grade 5) using reactive magnetron sputtering with increasing   oxygen content. To increase the grain size in the coating, all coatings   were post annealed at 385 degrees C. The obtained coating exhibited a gradual transition over 70 nm from crystalline titanium oxide (anatase)  at the surface to metallic Ti in the substrate, as shown using  cross-section transmission electron microscopy and X-ray photoelectron   spectroscopy depth pro. ling. Using scratch testing, it could be shown that the adhesion to the substrate was well above 1 GPa. The bioactivity of the coating was verified in vitro by the spontaneous   formation of hydroxylapatite upon storage in phosphate buffer solution at 37 degrees C for one week.   The described process can be applied to implants irrespective of bulk  metal in the base and should introduce the possibility to create safer permanent implants like reconstructive devices, dental, or spinal implants.

  • 8.
    Bruckner, Barbara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Johannes Kepler Univ Linz, IEP AOP, Altenbergerstr 69, A-4040 Linz, Austria.
    Bauer, Peter
    Johannes Kepler Univ Linz, IEP AOP, Altenbergerstr 69, A-4040 Linz, Austria.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    The impact of surface oxidation on energy spectra of keV ions scattered from transition metals2019In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 479, p. 1287-1292Article in journal (Refereed)
    Abstract [en]

    Studying the initial stages of surface oxidation is of great relevance to understand how oxygen alters the physical and chemical properties at the interface of the host material to the environment and is therefore, crucial for improvement in manifold technological applications. We investigated the influence of surface oxygen on ion spectra recorded for keV noble gas ions backscattered from metal surfaces in low energy ion scattering (LEIS). Initially pure Zn and Ta surfaces, chosen for their well-characterized properties in ion-neutralization in LEIS, have been oxidized and ion spectra for pure and oxidized surfaces have been compared. Oxygen on the surface significantly influences shape and intensity of the backscattered ion spectrum at all energies: for both metal systems, the surface scattered ion yield of the metal is drastically decreasing under oxygen presence. The observed decrease, however, cannot be explained by the reduction in the surface areal density of the metal constituents exclusively. At least for Zn an additional significant change in charge exchange behavior is necessary to explain the observations. In contrast to the generally observed decrease in the yield of ions scattered from the outermost surface, the change in shape and intensity of the reionization background are found to show opposing trends and different energy dependencies for Zn and Ta.

  • 9.
    Chakarov, D V
    et al.
    Chalmers University of Technology.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hellsing, B
    Chalmers University of Technology.
    Kasemo, B
    Chalmers University of Technology.
    Photos induced desorption and intercalation of potassium atoms deposited on graphite(0001)1996In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 106, p. 186-192Article in journal (Refereed)
    Abstract [en]

    In addition to the photodesorption phenomenon previously observed for single K atoms from a graphite surface covered with a monolayer of potassium we present new results related to the photon stimulated interaction of potassium with graphite, which concerns alternative routes for energy relaxation of the photo excited K adatoms: photoinduced intercalation. The desorption yield has a threshold at h omega approximate to 3 eV and a maximum at h omega(max) approximate to 4.9 eV, Polarization measurements indicate a substrate-mediated mechanism. The coverage dependence suggests that only the ionic 2D, K-phase is photo active. The proposed mechanism includes attachment of photo-generated hot electrons to the K 4s adsorbate resonance of energy E(res). Assuming an analogous excitation process we discuss different mechanisms for the K photo intercalation and possible applications of the photon stimulated doping of carboneous materials at low temperature.

  • 10.
    Chen, Zhang
    et al.
    Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Xiaoxiao, Zheng
    Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Jie, Cui
    Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061, China.
    Jiangwei, Liu
    School of Energy and Power Engineering, Shandong University, Jinan 250061, China.
    Duan, Tianbo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Baoqing, Zhang
    Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Zihao, Zhang
    Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Jafri, Hassan
    Department of Electrical Engineering, Mirpur University of Science and Technology (MUST), Mirpur Azad Jammu and Kashmir 10250, Pakistan.
    Papadakis, Raffaello
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. TdB Labs, Ultuna, Uppsala 75651, Sweden.
    Zhao, Qian
    Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061, China.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Making monolayer graphene photoluminescent by electron-beam-activated fluorination approach2023In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 608, article id 154593Article in journal (Refereed)
    Abstract [en]

    The past one and half decades have witnessed a tremendous development of graphene electronics, and the key to the success of graphene is its exceptional properties. The lacking of an inherent bandgap endows graphene with excellent electrical properties but considerably limits its applications in light-emitting and high-performance graphene-based devices. Herein, an approach for the direct writing of semiconducting and photoluminescent fluorinated graphene (C4F) patterns on monolayer graphene by an optimized electron-beam-activated fluorination technique is reported. A series of characterization approaches, such as atomic force microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy were used to demonstrate the successful preparation of C4F for maskless lithography. Specially, a sharp and strong photoluminescence located at the purple light range of ∼380 nm was observed in C4F, demonstrating a desirable semiconducting nature, and the bandgap was further confirmed by follow-up electrical measurements, where the C4F filed-effect transistor exhibited a p-type semiconductor behavior and significantly enhanced on/off ratio. Therefore, this work provides a novel technique for the fabrication of graphene devices for promising electronic and optoelectronic applications, but also opens a route towards the tailoring and engineering of electronic properties of graphene.

  • 11.
    Chow, Winnie W. Y.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Herwik, Stanislav
    Ruther, Patrick
    Göthelid, Emmanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Oscarsson, Sven
    Bio-polymer coatings on neural probe surfaces: Influence of the initial sample composition2012In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, no 20, p. 7864-7871Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of the study of hyaluronic acid (HyA) coating on two structural materials, silicon oxide (dielectric) surface and platinum (Pt) surface used for fabrication of probes developed for neurological investigations in the framework of the EU-project NeuroProbes. The silicon-based neural probes consist of multiple Pt electrodes on the probe shafts for neural recording applications. HyA coatings were proposed to apply on the probe surfaces to enhance the biocompatibility [1]. This study aims at understanding the influence of the initial composition of the probe surface on the structure and morphology of HyA coating. HyA was chemically functionalized by SS-pyridin using (N-Succinimidyl 3-[2-pyridyldithio]-propionate) (SPDP) and was immobilized on the surfaces via a covalent bond. The dielectric and Pt surfaces were derivatized by use of (3-mercaptopropyl) methyldimethoxysilane (MPMDMS). The silanol groups in MPMDMS bind to the dielectric surface, leaving the thiol groups at the uppermost surface and the thiol groups then bind covalently to the functionalized HyA. On the Pt surface, it is the thiol group which binds on the Pt surface. The coated surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). A well-defined HyA layer was observed on both dielectric and Pt surfaces. The coating of two molecular weights (340 kDa and 1.3 MDa) of HyA was examined. The influence of the silanized layer on the HyA coating was also investigated. 

  • 12.
    Coll, M.
    et al.
    CSIC, Inst Ciencia Mat Barcelona ICMAB, Campus UAB, Cerdanyola Del Valles 08193, Catalonia, Spain.
    Fontcuberta, J.
    CSIC, Inst Ciencia Mat Barcelona ICMAB, Campus UAB, Cerdanyola Del Valles 08193, Catalonia, Spain.
    Althammer, M.
    Bayer Akad Wissensch, Walther Meissner Inst, D-85748 Garching, Germany;Tech Univ Munich, Phys Dept, D-85748 Garching, Germany.
    Bibes, M.
    Univ Paris Sud, Univ Paris Saclay, Thales, Unite Mixte Phys,CNRS, F-91767 Palaiseau, France.
    Boschker, H.
    Max Planck Inst Solid State Res, Heisenbergstr 1, D-70569 Stuttgart, Germany.
    Calleja, A.
    OXOLUTIA SL, Avda Castell Barbera 26,Tellers 13,Nau 1, Barcelona 08210, Spain.
    Cheng, G.
    Univ Sci & Technol China, CAS Key Lab Microscale Magnet Resonance, Hefei 230026, Anhui, Peoples R China;Univ Sci & Technol China, Dept Modern Phys, Hefei 230026, Anhui, Peoples R China;Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA;Pittsburgh Quantum Inst, Pittsburgh, PA 15260 USA.
    Cuoco, M.
    Univ Salerno, CNR SPIN, IT-84084 Fisciano, SA, Italy;Univ Salerno, Dipartimento Fis ER Caianiello, IT-84084 Fisciano, SA, Italy.
    Dittmann, R.
    Forschungszentrum Julich, Peter Grunberg Inst PGI 7, D-52425 Julich, Germany.
    Dkhil, B.
    Univ Paris Saclay, CNRS UMR 8580, Cent Supelec, Lab Struct Proprietes & Modelisat Solides, F-91190 Gif Sur Yvette, France.
    El Baggari, I
    Cornell Univ, Dept Phys, Ithaca, NY 14853 USA.
    Fanciulli, M.
    Univ Milano Bicocca, Dept Mat Sci, Milan, Italy.
    Fina, I
    CSIC, Inst Ciencia Mat Barcelona ICMAB, Campus UAB, Cerdanyola Del Valles 08193, Catalonia, Spain.
    Fortunato, E.
    Univ NOVA Lisboa UNL, FCT, Dept Ciencia Mat, CENIMAT i3N, Lisbon, Portugal;CEMOP UNINOVA, P-2829516 Caparica, Portugal.
    Frontera, C.
    CSIC, Inst Ciencia Mat Barcelona ICMAB, Campus UAB, Cerdanyola Del Valles 08193, Catalonia, Spain.
    Fujita, S.
    Kyoto Univ, Kyoto 6158520, Japan.
    Garcia, V
    Univ Paris Sud, Univ Paris Saclay, Thales, Unite Mixte Phys,CNRS, F-91767 Palaiseau, France.
    Goennenwein, S. T. B.
    Tech Univ Dresden, Inst Festkorperphys, D-01062 Dresden, Germany;Tech Univ Dresden, Ctr Transport & Devices Emergent Mat, D-01062 Dresden, Germany.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Grollier, J.
    Univ Paris Sud, Univ Paris Saclay, Thales, Unite Mixte Phys,CNRS, F-91767 Palaiseau, France.
    Gross, R.
    Bayer Akad Wissensch, Walther Meissner Inst, D-85748 Garching, Germany;Tech Univ Munich, Phys Dept, D-85748 Garching, Germany;NIM, D-80799 Munich, Germany.
    Hagfeldt, A.
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland.
    Herranz, G.
    CSIC, Inst Ciencia Mat Barcelona ICMAB, Campus UAB, Cerdanyola Del Valles 08193, Catalonia, Spain.
    Hono, K.
    NIMS, Res Ctr Magnet & Spintron Mat, 1-2-1 Sengen, Tsukuba, Ibaraki 3050047, Japan.
    Houwman, E.
    Univ Twente, MESA Inst Nanotechnol, NL-7500 AE Enschede, Netherlands.
    Huijben, M.
    Univ Twente, MESA Inst Nanotechnol, NL-7500 AE Enschede, Netherlands.
    Kalaboukhov, A.
    Chalmers Univ Technol, Dept Microtechnol & Nanosci, MC2, Gothenburg, Sweden.
    Keeble, D. J.
    Univ Dundee, Sch Sci & Engn, Carnegie Lab Phys, SUPA, Dundee DD1 4HN, Scotland.
    Koster, G.
    Univ Twente, MESA Inst Nanotechnol, NL-7500 AE Enschede, Netherlands.
    Kourkoutis, L. F.
    Kavli Inst Cornell Nanoscale Sci, Ithaca, NY 14853 USA;Cornell Univ, Sch Appl & Engn Phys, Ithaca, NY 14853 USA.
    Levy, J.
    Bayer Akad Wissensch, Walther Meissner Inst, D-85748 Garching, Germany;Pittsburgh Quantum Inst, Pittsburgh, PA 15260 USA.
    Lira-Cantu, M.
    CSIC, Catalan Inst Nanosci & Nanotechnol ICN2, Campus UAB, E-08193 Barcelona, Spain;BIST, Campus UAB, E-08193 Barcelona, Spain.
    MacManus-Driscoll, J. L.
    Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England.
    Mannhart, Jochen
    Max Planck Inst Solid State Res, Heisenbergstr 1, D-70569 Stuttgart, Germany.
    Martins, R.
    Univ Milano Bicocca, Dept Mat Sci, Milan, Italy;IMM CNR, MDM Lab, Agrate Brianza, Italy.
    Menzel, S.
    Pittsburgh Quantum Inst, Pittsburgh, PA 15260 USA.
    Mikolajick, T.
    NaMLab gGmbH, Noethnitzer Str 64, D-01187 Dresden, Germany;Tech Univ Dresden, Chair Nanoelect Mat, D-01062 Dresden, Germany.
    Napari, M.
    Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England.
    Nguyen, M. D.
    Univ Twente, MESA Inst Nanotechnol, NL-7500 AE Enschede, Netherlands.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Paillard, C.
    Univ Arkansas, Phys Dept, Fayetteville, AR 72701 USA.
    Panigrahi, S.
    Univ NOVA Lisboa UNL, FCT, Dept Ciencia Mat, CENIMAT i3N, Lisbon, Portugal;CEMOP UNINOVA, P-2829516 Caparica, Portugal.
    Rijnders, G.
    Univ Twente, MESA Inst Nanotechnol, NL-7500 AE Enschede, Netherlands.
    Sanchez, F.
    CSIC, Inst Ciencia Mat Barcelona ICMAB, Campus UAB, Cerdanyola Del Valles 08193, Catalonia, Spain.
    Sanchis, P.
    Univ Politecn Valencia, Nanophoton Technol Ctr, Camino Vera S-N, E-46022 Valencia, Spain.
    Sanna, S.
    Tech Univ Denmark, Dept Energy Storage & Convers, DK-4000 Roskilde, Denmark.
    Schlom, D. G.
    Cornell Univ, Dept Phys, Lab Atom & Solid State Phys, Ithaca, NY 14853 USA;Cornell Univ, Dept Mat Sci & Engn, Ithaca, NY 14853 USA.
    Schroeder, U.
    NaMLab gGmbH, Noethnitzer Str 64, D-01187 Dresden, Germany.
    Shen, K. M.
    Kavli Inst Cornell Nanoscale Sci, Ithaca, NY 14853 USA;Cornell Univ, Dept Phys, Lab Atom & Solid State Phys, Ithaca, NY 14853 USA.
    Siemon, A.
    Rhein Westfal TH Aachen, Inst Werkstoffe Elektrotech IWE 2, D-52066 Aachen, Germany.
    Spreitzer, M.
    Jozef Stefan Inst, Adv Mat Dept, Jamova Cesta 39, Ljubljana 1000, Slovenia.
    Sukegawa, H.
    NIMS, Res Ctr Magnet & Spintron Mat, 1-2-1 Sengen, Tsukuba, Ibaraki 3050047, Japan.
    Tamayo, R.
    OXOLUTIA SL, Avda Castell Barbera 26,Tellers 13,Nau 1, Barcelona 08210, Spain.
    van den Brink, J.
    IFW Dresden, Inst Theoret Solid State Phys, Helm Holtzstr 20, D-01069 Dresden, Germany.
    Pryds, N.
    Tech Univ Denmark, Dept Energy Storage & Convers, DK-4000 Roskilde, Denmark.
    Granozio, F. Miletto
    CNR SPIN, Naples Unit, Complesso Univ Monte St Angelo,Via Cinthia, IT-80126 Naples, Italy.
    Towards Oxide Electronics: a Roadmap2019In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 482, p. 1-93Article in journal (Refereed)
    Abstract [en]

    At the end of a rush lasting over half a century, in which CMOS technology has been experiencing a constant and breathtaking increase of device speed and density, Moore's law is approaching the insurmountable barrier given by the ultimate atomic nature of matter. A major challenge for 21st century scientists is finding novel strategies, concepts and materials for replacing silicon-based CMOS semiconductor technologies and guaranteeing a continued and steady technological progress in next decades. Among the materials classes candidate to contribute to this momentous challenge, oxide films and heterostructures are a particularly appealing hunting ground. The vastity, intended in pure chemical terms, of this class of compounds, the complexity of their correlated behaviour, and the wealth of functional properties they display, has already made these systems the subject of choice, worldwide, of a strongly networked, dynamic and interdisciplinary research community.

    Oxide science and technology has been the target of a wide four-year project, named Towards Oxide-Based Electronics (TO-BE), that has been recently running in Europe and has involved as participants several hundred scientists from 29 EU countries. In this review and perspective paper, published as a final deliverable of the TO-BE Action, the opportunities of oxides as future electronic materials for Information and Communication Technologies ICT and Energy are discussed. The paper is organized as a set of contributions, all selected and ordered as individual building blocks of a wider general scheme. After a brief preface by the editors and an introductory contribution, two sections follow. The first is mainly devoted to providing a perspective on the latest theoretical and experimental methods that are employed to investigate oxides and to produce oxide-based films, heterostructures and devices. In the second, all contributions are dedicated to different specific fields of applications of oxide thin films and heterostructures, in sectors as data storage and computing, optics and plasmonics, magnonics, energy conversion and harvesting, and power electronics.

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  • 13.
    Cupak, C.
    et al.
    Vienna Univ Technol, Inst Appl Phys, Wiedner Hauptstr 8-10-E134, A-1040 Vienna, Austria.;Fus OAW, Vienna, Austria..
    Szabo, P. S.
    Vienna Univ Technol, Inst Appl Phys, Wiedner Hauptstr 8-10-E134, A-1040 Vienna, Austria.;Fus OAW, Vienna, Austria..
    Biber, H.
    Vienna Univ Technol, Inst Appl Phys, Wiedner Hauptstr 8-10-E134, A-1040 Vienna, Austria.;Fus OAW, Vienna, Austria..
    Stadlmayr, R.
    Vienna Univ Technol, Inst Appl Phys, Wiedner Hauptstr 8-10-E134, A-1040 Vienna, Austria.;Fus OAW, Vienna, Austria..
    Grave, C.
    Vienna Univ Technol, Inst Appl Phys, Wiedner Hauptstr 8-10-E134, A-1040 Vienna, Austria.;Fus OAW, Vienna, Austria..
    Fellinger, M.
    Vienna Univ Technol, Inst Appl Phys, Wiedner Hauptstr 8-10-E134, A-1040 Vienna, Austria.;Fus OAW, Vienna, Austria..
    Broetzner, J.
    Vienna Univ Technol, Inst Appl Phys, Wiedner Hauptstr 8-10-E134, A-1040 Vienna, Austria.;Fus OAW, Vienna, Austria..
    Wilhelm, R. A.
    Vienna Univ Technol, Inst Appl Phys, Wiedner Hauptstr 8-10-E134, A-1040 Vienna, Austria.;Fus OAW, Vienna, Austria..
    Moeller, W.
    Helmholtz Zentrum Dresden Rossendorf eV HZDR, Inst Ion Beam Phys & Mat Res, Bautzner Landstr 400, D-01328 Dresden, Germany..
    Mutzke, A.
    Max Planck Inst Plasma Phys, Wendelsteinstr 1, D-17491 Greifswald, Germany..
    Moro, Marcos V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Aumayr, F.
    Vienna Univ Technol, Inst Appl Phys, Wiedner Hauptstr 8-10-E134, A-1040 Vienna, Austria.;Fus OAW, Vienna, Austria..
    Sputter yields of rough surfaces: Importance of the mean surface inclination angle from nano- to microscopic rough regimes2021In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 570, article id 151204Article in journal (Refereed)
    Abstract [en]

    The roughness of a surface is known to have a strong influence on the sputtering process. Commonly used 1D Monte Carlo codes for calculating sputter yields show good agreement with experimental data only for comparably flat surfaces, whereas local ion incidence angles, shadowing and redeposition influence the sputter yields in both magnitude and angular dependence on rough surfaces. In the present work, we therefore investigated tungsten samples of largely different roughness, characterised by atomic force and confocal microscopy. A highly sensitive quartz crystal microbalance was used to determine sputter yields during ion irradiation. Low ion fluences were applied to ensure that the surface morphology did not change during irradiation. The results were used to benchmark our new ray-tracing simulation code SPRAY, which can take microscopy images without limitations in size as input. SPRAY was furthermore applied to perform systematic simulations for artificially roughened and computer-generated surfaces. A clear result was that the governing parameter for description of the sputtering behaviour is the mean value of the surface inclination angle distribution, rather than the commonly used root mean square roughness. Our simulations show that this parameter is universally applicable for a wide range of different surface structures.

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  • 14.
    Das, Sourav
    et al.
    Indian Inst Technol Kharagpur, Sch Nanosci & Technol, Kharagpur 721302, India..
    Pal, Sourabh
    Indian Inst Technol Kharagpur, Adv Technol & Dev Ctr, Kharagpur 721302, India..
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mandal, Debabrata
    Indian Inst Technol Kharagpur, Sch Nanosci & Technol, Kharagpur 721302, India..
    Giri, Soumen
    Indian Inst Technol Kharagpur, Mat Sci Ctr, Kharagpur 721302, India..
    Banerji, Pallab
    Indian Inst Technol Kharagpur, Sch Nanosci & Technol, Kharagpur 721302, India.;Indian Inst Technol Kharagpur, Adv Technol & Dev Ctr, Kharagpur 721302, India.;Indian Inst Technol Kharagpur, Mat Sci Ctr, Kharagpur 721302, India..
    Chandra, Amreesh
    Indian Inst Technol Kharagpur, Dept Phys, Kharagpur 721302, India..
    Basori, Rabaya
    Indian Inst Technol Kharagpur, Sch Nanosci & Technol, Kharagpur 721302, India..
    Hydrothermally grown SnS2/Si nanowire core-shell heterostructure photodetector with excellent optoelectronic performances2023In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 624, article id 157094Article in journal (Refereed)
    Abstract [en]

    Core-shell nanowire heterostructure is a new architecture for photodetector application with enlarged active surface area enhancing light absorption and photodetector performance. As an emanating coating material, SnS2 has a growing interest in next-generation optoelectronic materials. Here, we reported the enhanced optoelectronic performance of the hydrothermally grown SnS2 and Si nanowire (SiNWs) core-shell heterostructure. Hydrothermally grown SnS2 on Si nanowire creates a uniform coating over the entire surface of nanowires which enhances the heterostructure's effective junction area and improves optoelectronic performance over the broad spectral range (300 - 1100 nm). Specially, under 340 nm illumination, the core-shell photodetector exhibits large responsivity (-383 A/W) and extremely high external quantum efficiency (-2 x 105 %) at very low optical power (-20 nW/mm2). This SnS2/SiNWs core-shell heterostructure with significantly improved optoelectronic performance will be favourable for the development of photodetector with an ability to work with extremely high efficiency.

  • 15.
    David, Denis G.F.
    et al.
    Univ Fed Bahia, Inst Fis, Campus Univ Ondina, BR-40210340 Salvador, BA, Brazil.
    Godet, Christian
    Univ Rennes 1, CNRS, IPR, UMR 6251, F-35042 Rennes, France.
    Johansson, Fredrik O. L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Quantitative analysis of plasmon excitations in hard x-ray photoelectron spectra of bulk black phosphorus2020In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 505, article id 144385Article in journal (Refereed)
    Abstract [en]

    Black phosphorus (BPh) is a layered material with strong in-plane anisotropy of its structural and electronic properties; in spite of the great potential of BPh for conceptually new devices in optoelectronics and plasmonics, its fundamental electronic excitations have not yet been fully elucidated. In order to discriminate collective (plasmons) and single-particle (inter band transitions) excitations, we investigate the energy-loss distribution of P 1s photoelectrons in hard X-ray photoelectron spectra of BPh over a wide energy range. The energy-loss function (ELF), averaged over the principal directions of the BPh crystal, has been retrieved by using a Fourier Transform analysis to eliminate multiple inelastic scattering events. At low loss energies (1-8 eV), weak unresolved energy loss peaks are well described by DFT calculated inter band transitions, showing some anisotropy in the dielectric function epsilon(omega, q) tensor of BPh. At high loss energies, the ELF is dominated by the collective excitation of valence electrons with a peak energy at 20.1 +/- 0.2 eV, and weak anisotropy is found in the DFT calculated Im(- 1/epsilon) tensor. The anomalously small peak energy (9.0 +/- 0.5 eV) of a weak surface plasmon resonance is attributed either to low surface electron density in the terminal phosphorene layer or to some anisotropic surface plasmon propagation.

  • 16.
    Dobrota, Ana S.
    et al.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Pasti, Igor A.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Mentus, Slavko, V
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.;Serbian Acad Arts & Sci, Knez Mihajlova 35, Belgrade 11000, Serbia..
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Brinellvagen, S-10044 Stockholm, Sweden;Humboldt Univ, Phys Dept, Zum Grossen Windkanal 6, D-12489 Berlin, Germany..
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Brinellvagen, S-10044 Stockholm, Sweden.
    Altering the reactivity of pristine, N- and P-doped graphene by strain engineering: A DFT view on energy related aspects2020In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 514, article id 145937Article in journal (Refereed)
    Abstract [en]

    For carbon-based materials, in contrast to metal surfaces, a general relationship between strain and reactivity is not yet established, even though there are literature reports on strained graphene. Knowledge of such relationships would be extremely beneficial for understanding the reactivity of graphene-based surfaces and finding optimisation strategies which would make these materials more suitable for targeted applications. Here we investigate the effects of compressive and tensile strain (up to +/- 5%) on the structure, electronic properties and reactivity of pure, N-doped and P-doped graphene, using DFT calculations. We demonstrate the possibility of tuning the topology of the graphene surface by strain, as well as by the choice of the dopant atom. The reactivity of (doped) strained graphene is probed using H and Na as simple adsorbates of great practical importance. Strain can both enhance and weaken H and Na adsorption on (doped) graphene. In case of Na adsorption, a linear relationship is observed between the Na adsorption energy on P-doped graphene and the phosphorus charge. A linear relationship between the Na adsorption energy on flat graphene surfaces and strain is found. Based on the adsorption energies and electrical conductivity, potentially good candidates for hydrogen storage and sodiumion battery electrodes are discussed.

  • 17.
    Ershadi, Mahshid
    et al.
    Amirkabir Univ Technol, Dept Chem, Tehran, Iran.;Amirkabir Univ Technol, Renewable Energy Res Ctr, Tehran, Iran..
    Javanbakht, Mehran
    Amirkabir Univ Technol, Dept Chem, Tehran, Iran.;Amirkabir Univ Technol, Renewable Energy Res Ctr, Tehran, Iran..
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mozaffari, Sayed Ahmad
    Iranian Res Org Sci & Technol IROST, Dept Chem Technol, Tehran, Iran..
    Aghdam, Ali Molaei
    Amirkabir Univ Technol, Dept Chem Engn, Tehran Polytech, Tehran, Iran..
    Facile Synthesis of Amino-functionalized Mesoporous Fe3O4/rGO 3D Nanocomposite by Diamine compounds as Li-ion Battery Anodes2022In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 601, article id 154120Article in journal (Refereed)
    Abstract [en]

    Being an essential part of lithium-ion batteries, the development of novel anode materials currently receives much attention. Among these, the high theoretical capacity of Fe3O4 (924 mAh g(-1)) makes it highly promising. However, massive volumetric changes and particle aggregation during repeated insertion/de-insertion of lithium ions damage the electrode structure and destroy the electrical connection with the current collectors, resulting in rapid and significant capacity losses. One strategy to overcome this problem is the employment of graphene-based compounds as a substrate in an interconnected porous conductive network using a crosslinker (e.g., ethylene diamine) to adjust the distance between the graphene layers. Such a 3D framework creates enough available space for the lithium ions to be inserted or de-inserted respectively to or from the electrode during the charge-discharge process. Moreover, this strategy prevents large electrode volume changes and the accumulation of Fe3O4 during cycling. Herein, an ex situ method was used to synthesize amino-functionalized mesoporous Fe3O4/graphene-based nanocomposites. In the first step, Fe3O4 nanoparticles were synthesized with the addition of ethylenediamine (EDA), whereby mesoporous Fe3O4 nanoparticles were obtained (Fe3O4-E). In the second step, Fe3O4-E/rGO nanocomposites were prepared with the help of electrostatic interactions. The Fe3O4-E/rGO nanocomposite showed good cycling performance vs. Li-metal and a high reversible capacity (similar to 465 mAh g(-1)) and average coulombic efficiency of similar to 98% after 250 cycles at the current density of 1000 mA g(-1). These promising results can be attributed to the presence of EDA in the formation of mesoporous nanoparticles and the 3D structure of the resulting composite. It prevents the fragmentation of Fe3O4 particles induced by the formation of mesoporous structures and the restacking of rGO sheets generated by adjusting the layer spacing.

  • 18.
    Espinoza, Shirly
    et al.
    Czech Acad Sci, Inst Phys, ELI Beamlines, Na Slovance 2, Prague 18221, Czech Republic..
    Neuber, Gerd
    Univ Hamburg, Inst Nanostruct & Solid State Phys, Ctr Free Electron Laser Sci, Adv Study Grp APOG, Luruper Chaussee 149, D-22761 Hamburg, Germany..
    Brooks, Christopher D.
    Czech Acad Sci, Inst Phys, ELI Beamlines, Na Slovance 2, Prague 18221, Czech Republic..
    Besner, Bastian
    Univ Hamburg, Inst Nanostruct & Solid State Phys, Ctr Free Electron Laser Sci, Adv Study Grp APOG, Luruper Chaussee 149, D-22761 Hamburg, Germany..
    Hashemi, Maryam
    4 DOS GmbH, Wehmerweg 26, D-22529 Hamburg, Germany..
    Ruebhausen, Michael
    Univ Hamburg, Inst Nanostruct & Solid State Phys, Ctr Free Electron Laser Sci, Adv Study Grp APOG, Luruper Chaussee 149, D-22761 Hamburg, Germany..
    Andreasson, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics. Czech Acad Sci, Inst Phys, ELI Beamlines, Na Slovance 2, Prague 18221, Czech Republic.; Chalmers, Dept Phys, Condensed Matter Phys, Kemigarden 1, SE-41296 Gothenburg, Sweden..
    User oriented end-station on VUV pump-probe magneto-optical ellipsometry at ELI beamlines2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, no Part B, p. 378-382Article in journal (Refereed)
    Abstract [en]

    A state of the art ellipsometer for user operations is being implemented at ELI Beamlines in Prague, Czech Republic. It combines three of the most promising and exotic forms of ellipsometry: VUV, pump-probe and magneto-optical ellipsometry. This new ellipsometer covers a spectral operational range from the NIR up to the VUV, with high through-put between 1 and 40 eV. The ellipsometer also allows measurements of magneto-optical spectra with a 1 kHz switchable magnetic field of up to 1.5 T across the sample combining ellipsometry and Kerr spectroscopy measurements in an unprecedented spectral range. This form of generalized ellipsometry enables users to address diagonal and off-diagonal components of the dielectric tensor within one measurement. Pump-probe measurements enable users to study the dynamic behaviour of the dielectric tensor in order to resolve the time-domain phenomena in the femto to 100 ns range.

  • 19.
    Farkas, B.
    et al.
    Univ Szeged, Dept Opt & Quantum Elect, Szeged, Hungary; ELI HU Nonprofit Ltd, Szeged, Hungary.
    Heszler, P.
    Univ Szeged, Hungarian Acad Sci, Res Grp Laser Phys, Szeged, Hungary.
    Budai, J.
    Univ Szeged, Dept Opt & Quantum Elect, Szeged, Hungary.
    Oszko, A.
    Univ Szeged, Hungarian Acad Sci, React Kinet Res Grp, Szeged, Hungary.
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Geretovszky, Zs.
    Univ Szeged, Dept Opt & Quantum Elect, Szeged, Hungary.
    Optical, compositional and structural properties of pulsed laser deposited nitrogen-doped Titanium-dioxide2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 433, p. 149-154Article in journal (Refereed)
    Abstract [en]

    N-doped TiO2 thin films were prepared using pulsed laser deposition by ablating metallic Ti target with pulses of 248 nm wavelength, at 330 °C substrate temperature in reactive atmospheres of N2/O2 gas mixtures. These films were characterized by spectroscopic ellipsometry, X-ray photoelectron spectroscopy and X-ray diffraction. Optical properties are presented as a function of the N2 content in the processing gas mixture and correlated to nitrogen incorporation into the deposited layers. The optical band gap values decreased with increasing N concentration in the films, while a monotonically increasing tendency and a maximum can be observed in case of extinction coefficient and refractive index, respectively. It is also shown that the amount of substitutional N can be increased up to 7.7 at.%, but the higher dopant concentration inhibits the crystallization of the samples.

  • 20.
    Fredriksson, Wendy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Malmgren, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Germany.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Full depth profile of passive films on 316L stainless steel based on high resolution HAXPES in combination with ARXPS2012In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, no 15, p. 5790-5797Article in journal (Refereed)
    Abstract [en]

    Depth profiles of the passive films on stainless steel were based on analysis with the non-destructive hard X-ray photoelectron spectroscopy (HAXPES) technique in combination with the angular resolved X-ray photoelectron spectroscopy (ARXPS). The analysis depth with ARXPS is within the passive film thickness, while the HAXPES technique uses higher excitation energies (between 2 and 12 keV) also non-destructively probing the chemical content underneath the film. Depth profiles were done within and underneath the passive film of 316L polarized in acidic solution. The passive film thickness was estimated to 2.6 nm for a sample that was polarized at 0.6 V and the main component in the passive film is, as expected, chromium. From the high resolution HAXPES spectra we suggest chromium in three different oxidation states present. Also for iron three oxides were detected. Gradients of chromium and iron concentrations and oxidation states within the film and an enrichment of nickel within a 0.5 nm layer directly underneath the passive film are some of the results discussed. 

  • 21.
    Greczynski, G.
    et al.
    Linkoping Univ, IFM, Dept Phys, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hultman, L.
    Linkoping Univ, IFM, Dept Phys, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Reference binding energies of transition metal carbides by core-level x-ray photoelectron spectroscopy free from Ar+ etching artefacts2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 436, p. 102-110Article in journal (Refereed)
    Abstract [en]

    We report x-ray photoelectron spectroscopy (XPS) core level binding energies (BE's) for the widely-applicable groups IVb-VIb transition metal carbides (TMCs) TiC, VC, CrC, ZrC, NbC, MoC, HfC, TaC, and WC. Thin film samples are grown in the same deposition system, by dc magnetron co-sputtering from graphite and respective elemental metal targets in Ar atmosphere. To remove surface contaminations resulting from exposure to air during sample transfer from the growth chamber into the XPS system, layers are either (i) Ar+ ion-etched or (ii) UHV-annealed in situ prior to XPS analyses. High resolution XPS spectra reveal that even gentle etching affects the shape of core level signals, as well as BE values, which are systematically offset by 0.2-0.5 eV towards lower BE. These destructive effects of Ar+ ion etch become more pronounced with increasing the metal atom mass due to an increasing carbon-to-metal sputter yield ratio. Systematic analysis reveals that for each row in the periodic table (3d, 4d, and 5d) C 1s BE increases from left to right indicative of a decreased charge transfer from TM to C atoms, hence bond weakening. Moreover, C 1s BE decreases linearly with increasing carbide/metal melting point ratio. Spectra reported here, acquired from a consistent set of samples in the same instrument, should serve as a reference for true deconvolution of complex XPS cases, including multinary carbides, nitrides, and carbonitrides.

  • 22.
    Greczynski, G.
    et al.
    Linkoping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Lu, J.
    Linkoping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Hultman, L.
    Linkoping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Core-level spectra and binding energies of transition metal nitrides by non-destructive x-ray photoelectron spectroscopy through capping layers2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 396, p. 347-358Article in journal (Refereed)
    Abstract [en]

    We present the first measurements of x-ray photoelectron spectroscopy (XPS) core level binding energies (BE: s) for the widely-applicable group IVb-VIb polycrystalline transition metal nitrides (TMN's) TiN, VN, CrN, ZrN, NbN, MoN, HfN, TaN, and WN as well as AlN and SiN, which are common components in the TMN-based alloy systems. Nitride thin film samples were grown at 400.degrees C by reactive dc magnetron sputtering from elemental targets in Ar/ N-2 atmosphere. For XPS measurements, layers are either (i) Ar+ ion-etched to remove surface oxides resulting from the air exposure during sample transfer from the growth chamber into the XPS system, or (ii) in situ capped with a few nm thick Cr or W overlayers in the deposition system prior to air-exposure and loading into the XPS instrument. Film elemental composition and phase content is thoroughly characterized with time-of-flight elastic recoil detection analysis (ToF(-) ERDA), Rutherford backscattering spectrometry (RBS), and x-ray diffraction. High energy resolution core level XPS spectra acquired with monochromatic Al K alpha radiation on the ISO-calibrated instrument reveal that even mild etching conditions result in the formation of a nitrogen-deficient surface layer that substantially affects the extracted binding energy values. These spectra-modifying effects of Ar+ ion bombardment increase with increasing the metal atom mass due to an increasing nitrogen-to-metal sputter yield ratio. The superior quality of the XPS spectra obtained in a non-destructive way from capped TMN films is evident from that numerous metal peaks, including Ti 2p, V 2p, Zr 3d, and Hf 4f, exhibit pronounced satellite features, in agreement with previously published spectra from layers grown and analyzed in situ. In addition, the N/ metal concentration ratios are found to be 25-90% higher than those obtained from the corresponding ion-etched surfaces, and in most cases agree very well with the RBS and ToF-E ERDA values. The N 1 s BE: s extracted from capped TMN films, thus characteristic of a native surface, show a systematic trend, which contrasts with the large BE spread of literature "reference" values. Hence, non-destructive core level XPS employing capping layers provides an opportunity to obtain high-quality spectra, characteristic of virgin in situ grown and analyzed TMN films, although with larger versatility, and allows for extracting core level BE values that are more reliable than those obtained from sputter-cleaned N-deficient surfaces. Results presented here, recorded from a consistent set of binary TMN's grown under the same conditions and analyzed in the same instrument, provide a useful reference for future XPS studies of multinary materials systems allowing for true deconvolution of complex core level spectra.

  • 23.
    Göthelid, M.
    et al.
    KTH, MNF, SCI, Mat Fys, S-16440 Kista, Sweden..
    Hosseinpour, S.
    Univ Erlangen Nurnberg, Inst Particle Technol LFG, Cauerstr 4, D-91058 Erlangen, Germany..
    Ahmadi, Sareh
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Leygraf, C.
    KTH, Dept Chem, Div Surface & Corros Sci, S-10044 Stockholm, Sweden..
    Johnson, C. M.
    KTH, Dept Chem, Div Surface & Corros Sci, S-10044 Stockholm, Sweden..
    Hexane selenol dissociation on Cu: The protective role of oxide and water2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 423, p. 716-720Article in journal (Refereed)
    Abstract [en]

    Hexane selenol (CH3(CH2)(5)SeH) was adsorbed from gas phase in ultra-high vacuum on polycrystalline Cu and studied with synchrotron radiation based photoelectron spectroscopy (PES) and Near edge X-ray absorption fine structure spectroscopy (NEXAFS). Adsorption was done on a bare copper surface at room temperature (RT), on a thin oxide on Cu at room temperature, and on a thin layer of water on Cu at 140 K.

  • 24.
    Haman, Zakaryae
    et al.
    Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Lab Phys Mat & Modelisat Syst, Meknes, Morocco..
    Khossossi, Nabil
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Lab Phys Mat & Modelisat Syst, Meknes, Morocco..
    Kibbou, Moussa
    Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Lab Phys Mat & Modelisat Syst, Meknes, Morocco..
    Bouziani, Ilyas
    Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Lab Phys Mat & Modelisat Syst, Meknes, Morocco..
    Singh, Deobrat
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Essaoudi, Ismail
    Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Lab Phys Mat & Modelisat Syst, Meknes, Morocco..
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Lab Phys Mat & Modelisat Syst, Meknes, Morocco.;Max Planck Inst Phys Complexer Syst, NothnitzerStr 38, D-01187 Dresden, Germany..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat Sci & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Computational identification of efficient 2D Aluminium chalcogenides monolayers for optoelectronics and photocatalysts applications2021In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 556, article id 149561Article in journal (Refereed)
    Abstract [en]

    The massive consumption of traditional fossil fuel like oil, coal and natural gas has led to serious environmental issues, which drove the search for cleaner renewable energy sources. One such option is photocatalytic water splitting that has attracted much attention as a viable process for the large scale production of hydrogen as a renewable fuel. Within this perspective, we methodically studied the structural, optoelectronic, and photocatalytic properties of two-dimensional aluminum monochalcogenide monolayers with the chemical formula AlX (X = O, S, Se, and Te) based on the framework of Density Functional Theory (DFT). All considered structures are full relaxed and their thermodynamic stabilities are confirmed by computing the phonon spectrum and Ab Initio Molecular Dynamics (AIMD) simulations. The electronic characteristics are also performed on the basis of both exchange correlation functional GGA-PBE and HSE06 in order to obtain the accurate electronic band gap. According to our calculations, all the four monolayers posses indirect band gaps ranging between 1.937 and 2.46 eV. Furthermore, based on desirable electronic band gaps, the optical performance features were further explored including complex refractive index, absorption coefficient and energy loss function by means of the complex dielectric function. It is found that all the four materials present a high absorption coefficient in the visible and Ultra-Violet regions. Finally, the band edge positions of our monolayers straddle the reduction potential of H2 and the oxidation potential H2O. Also, it was found that the Gibbs free energy of 2D AlO monolayer is 0.02 eV at certain applied external electric field and very close to ideal catalysts which suggest that the AlO monolayer is better candidate for hydrogen production. Our findings demonstrate that AlX monolayers are suitable materials for optoelectronics and hydrogen production via photocatalytic water splitting.

  • 25.
    Haman, Zakaryae
    et al.
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Mat & Modelisat Syst LP2MS, Meknes, Morocco..
    Khossossi, Nabil
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Mat & Modelisat Syst LP2MS, Meknes, Morocco.;Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Kibbou, Moussa
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Mat & Modelisat Syst LP2MS, Meknes, Morocco..
    Bouziani, Ilyas
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Mat & Modelisat Syst LP2MS, Meknes, Morocco..
    Singh, Deobrat
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Mat & Modelisat Syst LP2MS, Meknes, Morocco..
    Essaoudi, Ismail
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Mat & Modelisat Syst LP2MS, Meknes, Morocco..
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Mat & Modelisat Syst LP2MS, Meknes, Morocco..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Indian Inst Technol Ropar, Dept Phys, Rupnagar 140001, Punjab, India..
    Janus Aluminum Oxysulfide Al2OS: A promising 2D direct semiconductor photocatalyst with strong visible light harvesting2022In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 589, article id 152997Article in journal (Refereed)
    Abstract [en]

    Hydrogen production via solar light-driven water dissociation has been regarded as an artificial and effective process to overcome the environmental problem as well as solving the current energy crisis. In this regard, numerous works have mainly been devoted to developing the appropriate photocatalyst which satisfies the conditions for water splitting and understanding the photocatalysis process. In this study, we propose for the first time the potential application of the two-dimensional Janus aluminum oxysulfide Al2OS as an efficient photocatalyst material for hydrogen-production H-2 through the first-principles calculations. Janus Al2OS monolayer has been designed from the parental binary aluminum sulfide AlS by substituting one sub-layer of sulfide atoms (S) to oxygen atoms (O). The electronic properties of the pristine AlS and the derived Janus Al2OS were computed using GGA-PBE and HSE06 functionals. According to the band structure, AlS monolayer shows a semiconductor behavior with an indirect bandgap of 2.14 eV whereas, the Janus Al2OS exhibits a direct bandgap of 1.579 eV. Motivated by the desirable bandgap of the Janus Al2OS, the absorption-coefficient of Janus Al2OS shows strong visible light harvesting compared to the parental AlS. Furthermore, the photocatalytic performance of Al2OS has been investigated. Our calculations demonstrate that the band edge position of Al2OS is suitable for the hydrogen evolution reaction (HER). More importantly, based on the reaction coordinate, it was found that the Gibbs free-energy Delta G(H*) of Al2OS is 0.97 eV which is smaller than of the two-dimensional Janus Ga2XY (X, Y = S, Se, Te with X not equal Y) reported recently. Moreover, this value decreases from 0.97 eV to 0.69 eV under 0.5 V/angstrom of an external electrical field. Our results indicate that Janus Al2OS fulfills the fundamental requirements for efficient photo-catalyst under visible light and provides new guidance for hydrogen-production via water splitting.

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  • 26.
    Han, Yuanyuan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Univ Manchester, Sch Elect & Elect Engn, Manchester M13 9PL, Lancs, England.
    Jafri, Syed Hassan Mujtaba
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur 10250, Azad Jammu & Ka, Pakistan.
    Ossipov, Dmitri A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Karolinska Inst, Dept Biosci & Nutr, S-17177 Stockholm, Sweden.
    Hilborn, Jöns
    Karolinska Inst, Dept Biosci & Nutr, S-17177 Stockholm, Sweden.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Optimization and analysis of pyrene-maltose functionalized graphene surfaces for Con A detection2020In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 510, article id 145409Article in journal (Refereed)
    Abstract [en]

    Utilizing the non-covalent pi-pi stacking of pyrene functionalized molecules onto graphene surfaces has achieved great success in the detection of various bio-objects, while the fundamental investigations on surface modifications stills remain rarely exploited. Here, we report the nano and atomic scale analysis of the pi-pi stacking functionalized graphene surface regarding to its surface topography, molecular self-assembly as well as process optimizations. The 'amphipathic' molecule, pyrene-maltose, is used for the non-covalent functionalization of graphene and systematical analysis is performed to understand the influence of different solvents on the molecular surface arrangement. Atomic force microscopy (AFM) and spectroscopy analysis indicate the successful formation of pyrene-maltose layer on graphene surface and it is further confirmed by scanning tunneling microscopy, depicting the self-assembled and densely packed pyrene-maltose layer that give distinguished and ordered diamond-shape lattice as compared to triangular lattice in pristine graphene. We also demonstrated that the interfacial adhesion forces between the AFM probe and the functionalized surfaces allow the detection of the lectin protein Concavalin A through selective absorption. This work provides essential evidence of the pi-pi interactions between pyrene molecules and graphene, and the AFM based adhesion measurement also has the potential to be employed in a variety of bio-detection applications.

  • 27. Hellwig, M. Ay. O
    et al.
    Becker, H. W.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Physics.
    Zabel, H.
    Oxidation of epitaxial Y(0001) films2008In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 254, no 10, p. 3184-3190Article in journal (Refereed)
    Abstract [en]

    We have investigated the oxidation behavior of MBE grown epitaxial Y(0 0 0 1)/Nb(1 1 0) films on sapphire (11 (2) over bar0) substrates at elevated temperatures under atmospheric conditions with a combination of experimental methods. At room temperature X-ray diffraction (XRD) reveals the formation of a 25 A thick YOxHx layer at the surface, while simultaneously oxide growth proceeds along defect lines normal to the film plane, resulting in the formation of a single crystalline cubic Y2O3 (2 2 2) phase. Furthermore, nuclear resonance analysis (NRA) reveals that hydrogen penetrates into the sample and transforms the entire Y film into the hydride YH2 phase. Additional annealing in air leads to further oxidation radially out from the already existing oxide channels. Finally material transport during oxidation results in the formation of conically shaped oxide precipitations at the surface above the oxide channels as observed by atomic force microscopy (AFM).

  • 28.
    Heszler, P.
    et al.
    Research Group of Laser Physics of the Hungarian Academy of Sciences, University of Szeged.
    Landström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Granqvist, Claes G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Laser-Induced Synthesis of Nanostructured Thin Films2007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 253, no 19, p. 8292-8299Article in journal (Refereed)
    Abstract [en]

    We present a number of important characteristics of laser techniques for preparation of nanostructured thin films with foci on laser ablation (LA) and laser-assisted chemical vapor decomposition (LCVD). Size-related features and structures of the deposited layers are associated with process parameters. Whenever possible, the performance of the deposits is compared to that of films prepared by other methods (e.g., physical vapor synthesis such as gas deposition, sputtering, etc.). The LA and LCVD methods allow a wide variety of materials to be prepared. A number of promising applications emerge when one combines this versatility with the potential for making certain types of nanostructured layers. These possibilities are also discussed.

  • 29.
    Hussain, T.
    et al.
    Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia.
    Singh, Deobrat
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. SV Natl Inst Technol, Dept Appl Phys, Adv Mat Lab, Surat 395007, Gujarat, India.
    Gupta, Sanjeev K.
    St Xaviers Coll, Dept Phys, Computat Mat & Nanosci Grp, Ahmadabad 380009, Gujarat, India.
    Karton, A.
    Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia.
    Sonvane, Yogesh
    SV Natl Inst Technol, Dept Appl Phys, Adv Mat Lab, Surat 395007, Gujarat, India.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden.
    Efficient and selective sensing of nitrogen-containing gases by Si2BN nanosheets under pristine and pre-oxidized conditions2019In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 469, p. 775-780Article in journal (Refereed)
    Abstract [en]

    Motivated by the promise of two-dimensional nanostructures in the field of gas sensing, we have employed van der Waals corrected density functional theory calculations to study the structural, electronic and gas sensing propensities of the recently designed Si2BN monolayer. Our rigorous simulations reveal that the representative members of nitrogen-containing gases (NCGs) such as NO, NO2 and NH3 binds extremely strongly on pristine Si2BN monolayer. However, a strong dissociative adsorption in case of NO and NO2 would poison the Si2BN and ultimately reversibility of the monolayer would be compromised. Exploring the sensing mechanism in more realistic pre-oxidized conditions, the binding characteristics of O2@Si2BN changed dramatically, resulting into much lower adsorption in associative manner for all NO, NO2 and NH3. A visible change in work function indicates the variation in conductivity of O2@Si2BN upon the exposure of incident gases. Sustainable values of binding energies would also ensure a quick recovery time that makes O2@Si2BN an efficient nano sensor for pollutants like NCGs.

  • 30.
    Hussain, T.
    et al.
    Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia;Univ Queensland, Australian Inst Bioengn & Nanotechnol, Ctr Theoret & Computat Mol Sci, Brisbane, Qld 4072, Australia.
    Vovusha, Hakkim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KAUST, Phys Sci & Engn Div PSE, Thuwal 239556900, Saudi Arabia.
    Umer, R.
    Univ Southern Queensland, Ctr Future Mat, Toowoomba, Qld 4350, Australia.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden.
    Superior sensing affinities of acetone towards vacancy induced and metallized ZnO monolayers2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 456, p. 711-716Article in journal (Refereed)
    Abstract [en]

    The sensing propensities of acetone molecule towards zinc oxide monolayers (ZnO-ML) have been studied by means of density functional theory (DFT) calculations. Our van der Waals induced first principles calculations revealed that pristine ZnO-ML barely binds acetone, which limits its application as acetone sensing materials. However the formation of vacancies and foreign element doping improves acetone binding drastically. Among several defects, divacancy, and metal doping Li, Sc and Ti functionalization on ZnO-ML has been found the most promising ones. Presence of dangling electrons and partial positive charges in case of vacancy-induced and metallized ZnO-ML respectively, is believed to enhance the binding of acetone on the monolayers. The acetone-ZnO binding behavior has been further explained through studying the electronic properties by density of states and charge transfer mechanism though Bader analysis. Thus defected and metallized ZnO-ML could be a promising nano sensor for efficient sensing/capture of acetone.

  • 31.
    Högström, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Fredriksson, Wendy
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Olsson, Claes-O. A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Cation profiling of passive films on stainless steel formed in sulphuric and acetic acid by deconvolution of angle-resolved X-ray photoelectron spectra2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 284, p. 700-714Article in journal (Refereed)
    Abstract [en]

    An approach for determining depth gradients of metal-ion concentrations in passive films on stainlesssteel using angle-resolved X-ray photoelectron spectroscopy (ARXPS) is described. The iterative method,which is based on analyses of the oxidised metal peaks, provides increased precision and hence allowsfaster ARXPS measurements to be carried out. The method was used to determine the concentrationdepth profiles for molybdenum, iron and chromium in passive films on 316L/EN 1.4432 stainless steelsamples oxidised in 0.5 M H2SO4 and acetic acid diluted with 0.02 M Na2B4O7 · 10H2O and 1 M H2O,respectively. The molybdenum concentration in the film is pin-pointed to the oxide/metal interface andthe films also contained an iron-ion-enriched surface layer and a chromium-ion-dominated middle layer.Although films of similar composition and thickness (i.e., about 2 nm) were formed in the two electrolytes,the corrosion currents were found to be three orders of magnitude larger in the acetic acid solution.The differences in the layer composition, found for the two electrolytes as well as different oxidationconditions, can be explained based on the oxidation potentials of the metals and the dissolution rates ofthe different metal ions.

  • 32.
    Intarasiri, Saweat
    et al.
    Institute for Science and Technology Research and Development, Chiang Mai University.
    Hallén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Lu, Jun
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Jensen, Jens
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Bertilsson, K.
    Mittuniversitetet.
    Wolborski, M.
    KTH.
    Singkarat, S.
    FNRF, Department of Physics, Faculty of Science, Chiang Mai University.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Crystalline quality of 3C-SiC formed by high-fluence C+-implanted Si2007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 253, no 11, p. 4836-4842Article in journal (Refereed)
    Abstract [en]

    Carbon ions at 40 keV were implanted into (1 0 0) high-purity p-type silicon wafers at 400 °C to a fluence of 6.5 × 1017 ions/cm2. Subsequent thermal annealing of the implanted samples was performed in a diffusion furnace at atmospheric pressure with inert nitrogen ambient at 1100 °C. Time-of-flight energy elastic recoil detection analysis (ToF-E ERDA) was used to investigate depth distributions of the implanted ions. Infrared transmittance (IR) and Raman scattering measurements were used to characterize the formation of SiC in the implanted Si substrate. X-ray diffraction analysis (XRD) was used to characterize the crystalline quality in the surface layer of the sample. The formation of 3C-SiC and its crystalline structure obtained from the above mentioned techniques was finally confirmed by transmission electron microscopy (TEM). The results show that 3C-SiC is directly formed during implantation, and that the subsequent high-temperature annealing enhances the quality of the poly-crystalline SiC.

  • 33.
    Jacobo-Martin, Alejandra
    et al.
    Ciudad Univ Cantoblanco, Madrid Inst Adv Studies Nanoscience IMDEA Nanosci, C Faraday 9, Madrid 28049, Spain..
    Hernandez, Jaime J.
    Ciudad Univ Cantoblanco, Madrid Inst Adv Studies Nanoscience IMDEA Nanosci, C Faraday 9, Madrid 28049, Spain..
    Solano, Eduardo
    ALBA Synchrotron, Carrer Llum 2 26, 08290 Cerdanyola Vall, Barcelona, Spain..
    Monclus, Miguel A.
    Tecnogetafe, IMDEA Mat Inst, C Eric Kandel 2, Getafe 28906, Spain..
    Martinez, Juan Carlos
    ALBA Synchrotron, Carrer Llum 2 26, 08290 Cerdanyola Vall, Barcelona, Spain..
    Fernandes, Daniel Filipe Félix
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Pedraz, Patricia
    Ciudad Univ Cantoblanco, Madrid Inst Adv Studies Nanoscience IMDEA Nanosci, C Faraday 9, Madrid 28049, Spain..
    Molina-Aldareguia, Jon M.
    Tecnogetafe, IMDEA Mat Inst, C Eric Kandel 2, Getafe 28906, Spain.;Univ Polit prime ecnica Madrid, Dept Mech Engn, Madrid 28006, Spain..
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Rodriguez, Isabel
    Ciudad Univ Cantoblanco, Madrid Inst Adv Studies Nanoscience IMDEA Nanosci, C Faraday 9, Madrid 28049, Spain..
    Resilient moth-eye nanoimprinted antireflective and self-cleaning TiO2 sputter-coated PMMA films2022In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 585, article id 152653Article in journal (Refereed)
    Abstract [en]

    Moth-eye nanostructures are amongst the most remarkable surfaces in nature because of their multi-functionality including antireflection, self-cleaning and bactericidal ability. Moth-eye surfaces consist of subwavelength arrays of tapered nanostructures, which are challenging to reproduce artificially. Nanoimprint lithography is probably one of the most suited technologies for this purpose. However, the poor mechanical resilience and durability of the polymeric nanocones when exposed to the environment, hinders their use in actual applications. To overcome these limitations, this work demonstrates the use of a thin oxide coating over the polymer moth-eye features imprinted on poly methyl methacrylate (PMMA) films. Particularly TiO2 conformal thin film coatings are deposited by unipolar pulsed dc magnetron sputtering over the antireflective nanopatterns acting as encapsulant. The coating, while preserving the antireflective properties, protects the nanostructures against mechanical scratching and improves substantially their thermal stability to over 250 ?. Furthermore, the TiO2 layer provides additional photoinduced self-cleaning functionality and at the same time it protects the matrix from UV photodegradation. The robust and durable antireflective surfaces developed here may find application on solar cells covers, flat panel displays or on optical components.

  • 34.
    Jeong, Heesu
    et al.
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Han, Jeong Woo
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Baek, Seungtae
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Kim, Sang Hyub
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Lee, Minho
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Yun, Yeonghun
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Kim, Byeong Jo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Jo, Hyunil
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Jung, Hyun Suk
    Sungkyunkwan Univ, Sch Adv Mat Sci & Engn, Suwon, South Korea..
    Park, Ik Jae
    Sookmyung Womens Univ, Dept Appl Phys, Seoul 04310, South Korea..
    Heo, Yeong-Woo
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Lee, Sangwook
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Room-Temperature-Grown amorphous Indium-Tin-Silicon-Oxide thin film as a new electron transporting layer for perovskite solar cells2022In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 581, article id 151570Article in journal (Refereed)
    Abstract [en]

    We report the amorphous quaternary oxide, indium-tin-silicon-oxide (ITSO), thin film as a new electron transport layer (ETL) for perovskite solar cells (PSCs). ITSO thin films are grown by magnetron co-sputtering indium-tin-oxide (ITO) and silicon oxide (SiO2) on commercial transparent conducting oxide (TCO) thin films at room temperature. As Si content increases (0-53.8 at%) the optical bandgap increases by approximately 1.3 eV and the electrical resistivity increases by six orders mainly because of the carrier concentration decrease. Consequently, the ITSO electronic structure depends largely on Si content. PSCs employing ITSO thin films as ETLs were fabricated to evaluate the effect of Si content on device performances. Si content influenced the shunt and series resistance. The optimized device was obtained using an ITSO film with 33.0 at% Si content, exhibiting 14.50% power-conversion efficiency. These results demonstrate that ITSO films are promising for developing efficient PSCs by optimizing the growing process and/or In/Sn/Si/O compositions. This approach can reduce PSC manufacturing process time and costs if ITO and ITSO are grown together by continuous sequential sputtering in a dual gun (ITO and SiO2) chamber.

  • 35.
    Jovanovic, Aleksandar
    et al.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia;Oberflachentechnol GmbH, CEST Kompetenzzentrum Elektrochem, Viktor Kaplan Str 2,Sect A, A-2700 Wiener Neustadt, Austria.
    Petkovic, Milena
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.
    Pasti, Igor A.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia;KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Sch Ind Engn & Managment, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden;Humboldt Univ, Phys Dept, Zum Grossen Windkanal 6, D-12489 Berlin, Germany.
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Tuning the electronic and chemisorption properties of hexagonal MgO nanotubes by doping: Theoretical study2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 457, p. 1158-1166Article in journal (Refereed)
    Abstract [en]

    Oxide materials offer a wide range of interesting physical and chemical properties. Even more versatile behavior of oxides is seen at the nanoscale, qualifying these materials for a number of applications. In this study we used DFT calculations to investigate the physical and chemical properties of small hexagonal MgO nanotubes of different length. We analyzed the effect of Li, B, C, N, and F doping on the properties of the nanotubes. We find that all dopants favor the edge positions when incorporated into the nanotubes. Doping results in the net magnetization whose value depends on the type of the impurity. Using the CO molecule as a probe, we studied the adsorption properties of pristine and doped MgO nanotubes. Our results show that the dopant sites are also the centers of significantly altered chemical reactivity. While pristine MgO nanotubes adsorb CO weakly, very strong adsorption at the dopant sites (B-, C-, and N-doped nanotubes) or neighboring edge atoms (F- and Li-doped nanotubes) is observed. Our results suggest that impurity engineering in oxide materials can be a promising strategy for the development of novel materials with possible use as selective adsorbents or catalysts.

  • 36.
    Kim, Seohan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Pusan Natl Univ, Mat Technol Res Inst, Busan 46241, South Korea.;Uppsala Univ, Dept Engn Sci, Angstrom Lab, SE-75121 Uppsala, Sweden..
    Yoon, Janghee
    Korea Basic Sci Inst, Busan Ctr, Busan 46742, South Korea..
    Park, Sungmin
    Pusan Natl Univ, Dept Mat Sci & Engn, Busan 46241, South Korea..
    Bang, Joonho
    Sungkyunkwan Univ, Dept Energy Sci, Suwon 16419, South Korea..
    Song, Pungkeun
    Pusan Natl Univ, Dept Mat Sci & Engn, Busan 46241, South Korea..
    Hydrogen-driven surface amorphization of the transparent oxide semiconductor thin-films for photovoltaic applications2021In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 555, article id 149702Article in journal (Refereed)
    Abstract [en]

    Crystalline transparent conductive oxides are promising candidates as front electrodes in electronic devices due to the high electron mobility and good optical transparency in the visible region. However, the rough surface morphology resulting from the grain growth during the deposition and post-annealing process triggers severe drawbacks in their thin-film applications. Here, we demonstrate the hydrogen-driven surface amorphization of the crystalline In?Sn?O (c-ITO) thin film. By introducing hydrogen gas during the deposition process, the surface of the c-ITO thin film is selectively amorphized, allowing for the smooth surface morphology while preserving the advantages of the crystalline thin film. The progressive surface amorphization of c-ITO thin film offers the tunability of the work function, leading to the improved power conversion efficiency of the thin-film solar cell. Our work provides a facile method to realize the smooth surface morphology of the c-ITO thin films, which can be further utilized for a wide range of crystalline thin films for optoelectronic applications.

  • 37.
    Kim, Yun-Ho
    et al.
    Chung Ang Univ, Dept Phys, Seoul 06974, South Korea..
    Kang, Min-Sung
    Chung Ang Univ, Dept Phys, Seoul 06974, South Korea..
    Choi, Jae Won
    Chung Ang Univ, Dept Phys, Seoul 06974, South Korea..
    Lee, Won-Yong
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics. Uppsala Univ, Dept Elect Engn, Div Solid State Elect, Uppsala, Sweden..
    Kim, Min-Jeong
    Chung Ang Univ, Dept Phys, Seoul 06974, South Korea..
    Park, No-Won
    Chung Ang Univ, Dept Phys, Seoul 06974, South Korea..
    Yoon, Young-Gui
    Chung Ang Univ, Dept Phys, Seoul 06974, South Korea..
    Kim, Gil-Sung
    Chung Ang Univ, Dept Phys, Seoul 06974, South Korea..
    Lee, Sang-Kwon
    Chung Ang Univ, Dept Phys, Seoul 06974, South Korea..
    Barrier-free semimetallic PtSe2 contact formation in two-dimensional PtSe2/PtSe2 homostructure for high-performance field-effect transistors2023In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 638, article id 158061Article in journal (Refereed)
    Abstract [en]

    The search for low-resistance metal contacts on two-dimensional (2D) layered transition metal dichalcogenide (TMDC) materials for high-performance electronic devices remains challenging owing to the lack of interfacial bonding on the surface and a strong Fermi-level pinning effect. In this study, we demonstrate a high-performance 2D large-area homostructured PtSe2/PtSe2 field-effect transistor (FET) by introducing a Schottky-barrier-free and semimetallic PtSe2 film (top layer) as an ohmic contact to semiconducting 2D PtSe2 films (bottom layer) via the wet-transfer method. We successfully improved the current on/off ratio of homostructured 2D/2D PtSe2/PtSe2 FET by more than approximately twofold increase compared to the PtSe2 FET with Pt contacts owing to the barrier-free homojunction PtSe2 layer. Our finding represents a significant achievement in obtaining highperformance electronic devices with barrier-free contacts on homostructured PtSe2 FETs and paves the way toward a promising strategy for wafer-scale 2D TMDC electronic devices.

  • 38.
    Kuzmin, Mikhail
    et al.
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland.;Russian Acad Sci, Ioffe Phys Tech Inst, 26 Polytekhnicheskaya, St Petersburg 194021, Russia..
    Lahtonen, Kimmo
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland..
    Vuori, Leena
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland..
    Sánchez-de-Armas, Rocío
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hirsimäki, Mika
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland..
    Valden, Mika
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland..
    Investigation of the structural anisotropy in a self-assembling glycinate layer on Cu(100) by scanning tunneling microscopy and density functional theory calculations2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 409, p. 111-116Article in journal (Refereed)
    Abstract [en]

    Self-assembling organic molecule-metal interfaces exhibiting free-electron like (FEL) states offers an attractive bottom-up approach to fabricating materials for molecular electronics. Accomplishing this, however, requires detailed understanding of the fundamental driving mechanisms behind the self assembly process. For instance, it is still unresolved as to why the adsorption of glycine ([NH2(CH2)COOH) on isotropic Cu(100) single crystal surface leads, via deprotonation and self-assembly, to a glycinate ([NH2(CH2)COO-]) layer that exhibits anisotropic FEL behavior. Here, we report on bias-dependent scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations for glycine adsorption on Cu(100) single crystal surface. We find that after physical vapor deposition (PVD) of glycine on Cu(100), glycinate self-assembles into an overlayer exhibiting c(2 x 4) and p(2 x 4) symmetries with non-identical adsorption sites. Our findings underscore the intricacy of electrical conductivity in nanomolecular organic overlayers and the critical role the structural anisotropy at molecule-metal interface plays in the fabrication of materials for molecular electronics.

  • 39.
    Lakhani, Krupa
    et al.
    Kadi Sarva Vishwavidyalaya, SMMPISR, Dept Phys, Gandhinagar 382015, India..
    Kansara, Shivam
    Kadi Sarva Vishwavidyalaya, SMMPISR, Dept Phys, Gandhinagar 382015, India.;Morgan State Univ, Dept Phys, Baltimore, MD 21251 USA..
    Gupta, Sanjeev K.
    St Xaviers Coll, Dept Phys, Computat Mat & Nanosci Grp, Ahmadabad 380009, Gujarat, India..
    Sonvane, Yogesh
    Sardar Vallabhbhai Natl Inst Technol, Dept Phys, Adv Mat Lab, Surat 395007, India..
    Seifu, Dereje
    Morgan State Univ, Dept Phys, Baltimore, MD 21251 USA..
    Gajjar, P. N.
    Gujarat Univ, Univ Sch Sci, Dept Phys, Ahmadabad 380009, Gujarat, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Indian Inst Technol IIT Ropar, Dept Phys, Rupnagar 140001, Punjab, India..
    Dissociation of air pollutants on the uniform surface of pentagonal BeP22021In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 570, article id 151061Article in journal (Refereed)
    Abstract [en]

    In this present work, the investigation was carried out using density functional theory (DFT) for the dissociation of noxious gas molecules such as carbon and nitrogen-based molecules (CO, CO2, N-2, NH3, NO, and NO2) on a pentagonal two-dimensional beryllium diphosphide (BeP2). The pentagonal BeP2 monolayer has a similar band structure as graphene. Here, some carbon and nitrogen-based noxious gases such as CO, CO2, N-2, NH3, NO, and NO2 with Van der Waals (vdW) interaction behave like physisorbed, while strong covalent (Be-O) interactions of O-2 on BeP2 formed chemisorption. Due to the chemisorption of O-2 gas molecules, the bandgap at Dirac point at P-site on BeP2 opens. While CO, CO2, N-2, NO, and NO2 are dissociated at the C-site, only CO, N-2, and NO are dissociated at the P-site. Beryllium diphosphide's band-gap shifts resulting from interactions with CO, N-2, and O-2 molecules are just 6%, 12.1%, and 22.2%, respectively, meaning that the BeP2 material has a moderate and high sensitivity towards CO, N-2, and O-2 molecules. BeP2 appears to be a potential catalyst for the dissociation of CO, CO2, N-2, NO, NO2, and O-2 gas molecules, which is even more interesting.

  • 40. Lauridsen, J.
    et al.
    Nedfors, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jensen, J.
    Eklund, P.
    Hultman, L.
    Ti-B-C nanocomposite coatings deposited by magnetron sputtering2012In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, no 24, p. 9907-9912Article in journal (Refereed)
    Abstract [en]

    Ti-B-C nanocomposite coatings with a B content of 8-17 at.% have been deposited by magnetron sputtering from B4C, Ti, and C targets. X-ray diffraction, photoelectron spectroscopy, and electron microscopy show that the coatings consist of nanocrystalline (nc) TiC: B embedded in a matrix of amorphous (a) C, BCx, TiOx and BOx. The fraction of amorphous phase scales with the Ti concentration, where the matrix predominantly consists of free C with some BCx in coatings with a C/Ti ratio > 1, while the matrix predominantly consists of BCx with some free C in coatings with a C/Ti ratio < 1. nc-TiC:B/a-BCx/a-C coatings with low amount of free C exhibit a contact resistance comparable to the contact resistance of an Ag sputtered coating at loads of similar to 1 N against an Au probe, despite the O content of similar to 16 at.%.

  • 41.
    Lee, Minho
    et al.
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Park, Ik Jae
    Seoul Natl Univ, Dept Mat Sci & Engn, Seoul 08826, South Korea.;Seoul Natl Univ, Res Inst Adv Mat RIAM, Seoul 08826, South Korea..
    Jeong, Heesu
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Kim, Byeong Jo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Yun, Yeonghun
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Kim, Hae Jin
    Seoul Natl Univ, Dept Mat Sci & Engn, Seoul 08826, South Korea..
    Cho, Hanbyeol
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Lee, Sangwook
    Kyungpook Natl Univ, Sch Mat Sci & Engn, Daegu 41566, South Korea..
    Thermal-assisted photo-annealed TiO2 thin films for perovskite solar cells fabricated under ambient air2020In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 530, article id 147221Article in journal (Refereed)
    Abstract [en]

    We report herein a facile process for the fabrication of amorphous TiO2 thin films under ambient atmosphere using thermal-assisted UV-annealing (similar to 125 degrees C). The TiO2 films were prepared via spin-coating titanium diisopropoxide bis(acetylacetonate) precursor and sequential photo-annealing at various temperatures. Additional soft annealing during the UV-annealing altered the surface chemical states and electrical band structures of the amorphous TiO2 films. The UV-annealing at room temperature leads to a higher conduction band minimum level of the film and a smaller amount of hydroxyl group at the film surface, compared to the thermal-assisted (100-250 degrees C) UV-annealing or the thermal-only annealing (500 degrees C). Effects of the temperature during the UV-annealing process on photovoltaic properties were investigated by fabricating planar heterojunction perovskite cells with methylammonium lead triiodide under ambient atmosphere. At higher temperature of 100-150 degrees C, compared to room temperature, fill factor and power conversion efficiency were enhanced, and hysteresis in current-voltage curves were reduced. Impedance analysis demonstrates that the capacitance is significantly reduced, leading to suppressed hysteresis of the perovskite solar cells. Finally, we achieved a power-conversion efficiency of 20.36% (for the reverse scan) and a stabilized power output of 18.57% from a 125 degrees C -photo-annealed TiO2-based device.

  • 42.
    Lewin, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Empa, Lab Nanoscale Mat Sci, Uberlandstr 129, CH-8600 Dubendorf, Switzerland.
    Counsell, Jonathan
    Kratos Analyt Ltd, Trafford Wharf Rd, Manchester M17 1G, Lancs, England.
    Patscheider, Jörg
    Empa, Lab Nanoscale Mat Sci, Uberlandstr 129, CH-8600 Dubendorf, Switzerland;Evatec AG, Trubbach, Switzerland.
    Spectral artefacts post sputter-etching and how to cope with them - A case study of XPS on nitride-based coatings using monoatomic and cluster ion beams2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 442, p. 487-500Article in journal (Refereed)
    Abstract [en]

    The issue of artefacts due to sputter-etching has been investigated for a group of AlN-based thin film materials with varying thermodynamical stability. Stability of the materials was controlled by alloying AlN with the group 14 elements Si, Ge or Sn in two different concentrations. The coatings were sputter-etched with monoatomic Ar+ with energies between 0.2 and 4.0 keV to study the sensitivity of the materials for sputter damage. The use of Ar-n(+) clusters to remove an oxidised surface layer was also evaluated for a selected sample. The spectra were compared to pristine spectra obtained after in-vacuo sample transfer from the synthesis chamber to the analysis instrument. It was found that the all samples were affected by high energy (4 keV) Ar+ ions to varying degrees. The determining factors for the amount of observed damage were found to be the materials' enthalpy of formation, where a threshold value seems to exist at approximately -1.25 eV/atom (similar to-120 kJ/mol atoms). For each sample, the observed amount of damage was found to have a linear dependence to the energy deposited by the ion beam per volume removed material. Despite the occurrence of sputter-damage in all samples, etching settings that result in almost artefact-free spectral data were found; using either very low energy (i.e. 200 eV) monoatomic ions, or an appropriate combination of ion cluster size and energy. The present study underlines that analysis post sputter-etching must be carried out with an awareness of possible sputter-induced artefacts.

  • 43.
    Lilja, Mirjam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Butt, Umer
    Sandvik Coromant.
    Bjöörn, Dorota
    Sandvik Coromant.
    Shen, Zhijian
    Nucleation and growth of hydroxyapatite on arc-deposited TiO2surfaces studied by quartz crystal microbalance with dissipation2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 284, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Understanding of nucleation and growth kinetics of biomimetically deposited hydroxyapatite (HA) oncrystalline TiO2surfaces is important with respect to the application and performance of HA as functionalimplant coatings. Arc-evaporation was used to deposit TiO2coatings dominated by anatase phase, rutilephase or their mixtures. Subsequent formation of HA from phosphate buffered saline solution (PBS) wasinvestigated in real-time using in situ quartz crystal microbalance with dissipation technique (QCM-D). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to characterize thepresence, morphology and crystal structure of TiO2coatings and the formed HA. Increasing temperature ofthe PBS, increasing flow rate and applying a higher ion concentration in solution were found to accelerateHA nucleation process and hence affect growth kinetics. Lower PBS temperature resulted in the formationof HA coatings with flake-like morphology and increasing HA porosity. All TiO2coatings under studyenabled HA formation at body temperature, while in contrast Ti reference surfaces only supported HAnucleation and growth at elevated temperatures. QCM-D technique is a powerful tool for studying theimpact of process parameters during biomimetic coating deposition on coating structure evolution in realtime and provides valuable information for understanding, optimizing as well as tailoring the biomimeticHA growth processes.

  • 44.
    Lindahl, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of strontium ions on the early formation of biomimetic apatite on single crystalline rutile2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 266, p. 199-204Article in journal (Refereed)
    Abstract [en]

    Single crystalline rutile is a good model to investigate the growth mechanism of hydroxyapatite on bioactive Ti surfaces. Previous studies have shown the difference on different crystalline rutile faces in the early stage and during the growth of HAp crystals from simulated body fluids. It is known that the biological apatite crystal is an ion-substituted apatite. Ion substitution will influence the HAp crystal growth and morphology. In the present study, the effect of strontium ions on the adsorption of Ca and phosphate ions on three different faces of single crystalline rutile substrates has been investigated. The ion adsorption is the crucial step in the nucleation of HAp crystals on specific surfaces. Single crystalline rutile surfaces ((1 1 0), (1 0 0) and (0 0 1)) were soaked in phosphate buffer solutions containing calcium and strontium ions for different time periods. The results showed that the adsorption of Sr, Ca and P is faster on the (1 1 0) surface than on the (1 0 0) and (0 0 1) surfaces. Almost same amount of Sr ion was adsorbed on the surfaces compared to the adsorption of Ca ion. Strontium ion influenced the biological apatite formation in the early stage in this study.

  • 45.
    Lindahl, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Snis, Anders
    Arcam AB, Sweden.
    Lausmaa, Jukka
    Palmquist, Anders
    Department of Biomaterials, Sahlgrenska Academy at the University of Gothenburg, Gothenburg.
    Biomimetic calcium phosphate coating of additively manufactured porous CoCr implants2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 353, p. 40-47Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to study the feasibility to use a biomimetic method to prepare biomimetic hydroxyapatite (HA) coatings on CoCr substrates with short soaking times and to characterize the properties of such coatings. A second objective was to investigate if the coatings could be applied to porous CoCr implants manufactured by electron beam melting (EBM). The coating was prepared by immersing the pretreated CoCr substrates and EBM implants into the phosphate-buffered solution with Ca2+ in sealed plastic bottles, kept at 60 degrees C for 3 days. The formed coating was partially crystalline, slightly calcium deficient and composed of plate-like crystallites forming roundish flowers in the size range of 300-500 nm. Cross-section imaging showed a thickness of 300-500 nm. In addition, dissolution tests in Tris-HCl up to 28 days showed that a substantial amount of the coating had dissolved, however, undergoing only minor morphological changes. A uniform coating was formed within the porous network of the additive manufactured implants having similar thickness and morphology as for the flat samples. In conclusion, the present coating procedure allows coatings to be formed on CoCr and could be used for complex shaped, porous implants made by additive manufacturing.

  • 46.
    Magnuson, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II.
    Butorin, Sergei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II.
    Werme, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II.
    Nordgren, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II.
    Ivanov, Kiril
    Guo, Jinghua
    Shuh, David
    Uranium oxides investigated by X-ray absorption and emission spectroscopies2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5615-5618Article in journal (Refereed)
    Abstract [en]

    X-ray absorption and resonant X-ray emission measurements at the O 1s edge of the uranium oxides UO2, U3O8 and UO3 are presented. The spectral shapes of the O Kα X-ray emission spectra of UO3 exhibit significant excitation energy dependence, from an asymmetric to a symmetric form, which differs from those of UO2 and U3O8. This energy dependence is attributed to a significant difference in the oxygen–uranium hybridization between two different sites in the crystal structure of UO3. The spectral shapes of UO2 and U3O8 are also found to be different but without significant energy dependence. The experimental spectra of the valence and conduction bands of the uranium oxides are compared to the results of electronic structure calculations available in the literature.

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  • 47.
    Majumdar, Arnab
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Yang, Xiaoyong
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala Univ, Dept Phys & Southwest Univ Sci & Technol, Mianyang 621010, Sichuan, Peoples R China..
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chowdhury, Suman
    Skolkovo Innovat Ctr, Skolkovo Inst Sci & Technol, 3 Nobel St, Moscow 121205, Russia..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Indian Inst Technol, Discipline Phys, Indore 453552, Madhya Pradesh, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    High exothermic dissociation in van der Waals like hexagonal two dimensional nitrogene from first-principles molecular dynamics2020In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 529, article id 146552Article in journal (Refereed)
    Abstract [en]

    Mono and multilayered two dimensional (2D) nitrogene in which nitrogen atoms are single bonded are studied for energy applications. The structures are observed to be dynamically and thermally stable at room temperature but dissociate into triple bonded N-2 molecules at higher temperatures. From ab initio molecular dynamics simulations, the dissociation temperature is found to be decreasing with increasing number of layers (1500 K for single layer and 500 K for six layers). The energy released for the different layered cases is large due to the energy difference between single and triple-bonded nitrogen (similar to 0.88 - 1.8 eV/atom). Significantly high energy densities calculated for the multilayered structures (similar to 6 - 12.3 kJ/gm) can secure these materials an important position amongst non-nuclear and inorganic high energy density materials known today. We believe that this work will shed light on synthesizing next generation non-nuclear environmentally clean high energy density materials using multi-layer nitrogene that detonate at not very high temperatures.

  • 48.
    Meier de Andrade, Ageo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Broqvist, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Controlling the metal work function through atomic-scale surface engineering2022In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 589, article id 152932Article in journal (Refereed)
    Abstract [en]

    Adsorbate induced work function modification of Ni have been investigated by means of first-principles calculations. More specifically, the adsorption of Li, Na, Si, Zr, Pd, Pt, or Sn at various coverages on Ni low-index surface models have been considered. In the case of Sn, a more thorough investigation was performed comparing the adsorption as an overlayer structure with the case of surface alloy formation. Our calculations suggest that the most stable Sn@Ni configuration corresponds to a surface alloy, and here the Ni(100)c(2 × 2)-Sn, Ni(110)c(2 × 2)-Sn, and Ni(111)()R30-Sn surface alloys were found to display similar stability. Concerning the induced work function change, a different behaviour as a function of coverage was observed depending on the nature of the Sn@Ni surface model. Both overlayer adsorption and surface alloying were found to induce a work function decrease already at relatively low coverages ( 0.05 atom Å −2), regardless of the underlying surface orientation. However, while the work function obtained for stable surface alloys was found to monotonously decrease as the coverage increases, the work function for the stable overlayer structures goes through a minimum. For all investigated surface modifications, the change in work function was found to be consistent with the orientation of the charge transfer at the adsorbate–surface interface. The computed data in this work may serve as handles for experimental endeavours aiming to optimize properties of active materials through atomic-scale surface engineering.

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  • 49.
    Nafday, Dhani
    et al.
    Asia Pacific Ctr Theoret Phys, Pohang 790784, Gyeonbuk, South Korea..
    Richter, Christine
    CY Cergy Paris Univ, Lab Phys Mat & Surfaces, 5 Mail Gay Lussac, F-95031 Cergy Pontoise, France.;Univ Paris Saclay, LIDYL, CNRS, CEA, F-91191 Gif Sur Yvette, France..
    Heckmann, Olivier
    CY Cergy Paris Univ, Lab Phys Mat & Surfaces, 5 Mail Gay Lussac, F-95031 Cergy Pontoise, France.;Univ Paris Saclay, LIDYL, CNRS, CEA, F-91191 Gif Sur Yvette, France..
    Wang, Weimin
    Lund Univ, Max IV Lab, POB 118, S-22100 Lund, Sweden..
    Mariot, Jean-Michel
    Sorbonne Univ, CNRS, Lab Chim Phys Matiere & Rayonnement, 4 Pl Jussieu, F-75252 Paris 05, France..
    Djukic, Uros
    CY Cergy Paris Univ, Lab Phys Mat & Surfaces, 5 Mail Gay Lussac, F-95031 Cergy Pontoise, France..
    Vobornik, Ivana
    CNR, TASC Lab, Ist Off Mat, Area Sci Pk Basovizza,Str Statale 14,Km 163-5, I-34149 Trieste, Italy..
    Lefevre, Patrick
    Synchrotron SOLEIL, Dept 128, F-91190 St Aubin, France..
    Taleb-Ibrahimi, Amina
    Synchrotron SOLEIL, Dept 128, F-91190 St Aubin, France..
    Rault, Julien
    Synchrotron SOLEIL, Dept 128, F-91190 St Aubin, France..
    Nicolai, Laurent
    Synchrotron SOLEIL, Dept 128, F-91190 St Aubin, France..
    Ong, Chin Shen
    Univ West Bohemia, New Technol Res Ctr, Plzen 30100, Czech Republic..
    Thunström, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hricovini, Karol
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Minar, Jan
    CY Cergy Paris Univ, Lab Phys Mat & Surfaces, 5 Mail Gay Lussac, F-95031 Cergy Pontoise, France.;Univ Paris Saclay, LIDYL, CNRS, CEA, F-91191 Gif Sur Yvette, France..
    Di Marco, Igor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Asia Pacific Ctr Theoret Phys, Pohang 790784, Gyeonbuk, South Korea.;Pohang Univ Sci & Technol, Dept Phys, Pohang 790784, Gyeonbuk, South Korea.
    Electronic structure of Bi nanolines on InAs(100)2023In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 611, article id 155436Article in journal (Refereed)
    Abstract [en]

    Self-assembled nanolines are attractive to build the technological devices of next generation, but characterizing their electronic properties is often difficult to achieve. In this work we employ angle-resolved photoemission spectroscopy and density functional theory to clarify the electronic structure exhibited by self-assembled Bi nanolines grown on the InAs(100) surface. A surface resonance associated to the reconstructed zeta(4 x 2) surface is visible in the photoemission spectra before and after the formation of the Bi nanolines. This demonstrates that Bi deposition does not necessarily drive a transition to an unreconstructed surface in the substrate, which is contrary to what was reported in previous studies. In addition, experiment and theory show the presence of a flat band located in the band gap of InAs, just above the valence band maximum. This flat band is associated to the Bi nanolines and possesses a strong orbital character, consistent with its unidimensional nature. These spectral features suggest that Bi nanolines on InAs(100) may have a strongly polarized conductivity, which makes them suitable to be exploited as nanowires in nanotechnology. The coexistence with an accumulation layer suggests an even farther functionalization.

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  • 50.
    Naqvi, Syeda R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hussain, Tanveer
    School of Molecular Sciences, University of Western Australia, Perth.
    R. Gollu, Sankara
    Organic Materials Innovation Centre, School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom.
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology (KTH), S-100 44 Stockholm, Sweden.
    Superior sensitivity of metal functionalized boron carbide (BC3) monolayer towards carbonaceous pollutants2020In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 512, article id 145637Article in journal (Refereed)
    Abstract [en]

    The sensitivity of light metal functionalized boron carbide (BC3) sheets towards selected carbonaceous gases like CO, CO2, and CH4 is investigated by using first principles density functional theory calculations. We find that functionalization with alkali (Li, Na, K) and alkaline earth metals (Be, Mg, Ca), is a useful strategy to improve the sensitivity of graphene-like BC3 towards the mentioned gases. A semiconductor-to-metal transformation of BC3 is observed upon the introduction of metal dopants. Gas molecules are adsorbed on the metallized BC3 through weak chemisorption, which is an ideal scenario for gas sensing under practical working conditions. We find that the adsorption energies (Eads) of CO molecule are found to be 1.71, 0.48, 0.34, 0.35, 0.96, and 0.84 eV on Be-, Li-, Na-, K-, Mg-, and Ca-doped BC3, respectively. Similarly, CO2 binds to Li-, Be-, Mg-, and Ca- doped BC3 with Eads of 0.54, 0.87, 0.61, and 0.43 eV, respectively. For CH4, an Eads value of 0.74 eV turns out to be the strongest in case of Be-BC3. Bader charge analysis divulges that the transfer of charges results in the adsorption mechanism of the gases to the metallized BC3. In addition to feasible Eads, change in the work function upon the adsorption of gas molecules further confirms good sensitivity of the metallized BC3 towards CO, CO2and CH4. Based on our findings, we deduce that metal-doped BC3 is an excellent candidate for the efficient sensing of harmful pollutants.

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