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  • 1.
    Adam, Stefan
    et al.
    Leibniz Institute Polymerforsch eV, Germany; Technical University of Dresden, Germany.
    Koenig, Meike
    Leibniz Institute Polymerforsch eV, Germany; Technical University of Dresden, Germany; Karlsruhe Institute Technology, Germany.
    Rodenhausen, Keith Brian
    University of Nebraska, NE 68588 USA; Biolin Science Inc, NJ 07652 USA.
    Eichhorn, Klaus-Jochen
    Leibniz Institute Polymerforsch eV, Germany.
    Oertel, Ulrich
    Leibniz Institute Polymerforsch eV, Germany.
    Schubert, Mathias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Leibniz Institute Polymerforsch eV, Germany; University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA.
    Stamm, Manfred
    Leibniz Institute Polymerforsch eV, Germany; Technical University of Dresden, Germany.
    Uhlmann, Petra
    Leibniz Institute Polymerforsch eV, Germany; University of Nebraska, NE 68588 USA.
    Quartz crystal microbalance with coupled Spectroscopic Ellipsometry-study of temperature-responsive polymer brush systems2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, s. 843-851Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using a combined setup of quartz crystal microbalance with dissipation monitoring together with spectroscopic ellipsometry, the thermo-responsive behavior of two different brush systems (poly(N-isopropyl acrylamide) and poly(2-oxazoline)s) was investigated and compared to the behavior of the free polymer in solution. Poly(2-oxazoline)s with three different hydrophilicities were prepared by changing the content of a hydrophilic comonomer. While both polymer types exhibit a sharp, discontinuous thermal transition in solution, in the brush state the transition gets broader in the case of poly(N-isopropyl acrylamide) and is transformed into a continuous transition for poly(2-oxazoline)s. The position of the transition in solution is influenced by the degree of hydrophilicity of the poly(2-oxazoline). The difference in areal mass detected by quartz crystal microbalance and by spectroscopic ellipsometry, has been attributed to the chain segment density profile of the polymer brushes. Applying this density profile information, for poly(N-isopropyl acrylamide) two different swelling stages could be identified, while for poly(2-oxazoline) the transition between a parabolic and more step-wise profile is found continuous. The different swelling characteristics were attributed to the different miscibility behavior types, with the brush state acting similar to a crosslinked system. (C) 2017 Elsevier B.V. All rights reserved.

  • 2. Amandusson, H.
    et al.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Dannetun, Helen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Effect of CO and O2 on hydrogen permeation through a palladium membrane2000Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 153, nr 4, s. 259-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydrogen permeation through a 25-µm thick palladium membrane during continuous exposures of hydrogen together with different combinations of oxygen and carbon monoxide has been studied at membrane temperatures of 100 °C-250 °C (total pressures of 40-150 Torr). Both CO and O2, individually, inhibit hydrogen permeation through the membrane. The cause of the inhibition is, however, somewhat different. CO blocks available hydrogen dissociation sites, while oxygen both blocks dissociation sites and also consumes adsorbed hydrogen through the production of water. When a combination of CO and O2 is supplied together with hydrogen, new reaction pathways will emerge. The carbon dioxide formation will dominate the water forming reaction, and consequently, the blocking effect caused by the formation of water will be suppressed. In a mixture of CO+O2+H2, the hydrogen permeation can become either larger or smaller than that due to only O2+H2 or CO+H2 depending on the CO/O2 ratio. It is thus possible to find a situation where carbon monoxide and oxygen react to form CO2 leaving adsorbed hydrogen free to permeate the membrane.

  • 3.
    Armakavicius, Nerijus
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Bouhafs, Chamseddine
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Stanishev, Vallery
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Kühne, Philipp
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Knight, Sean
    Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, USA.
    Hofmann, Tino
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, USA / Department of Physics and Optical Science, University of North Carolina at Charlotte, USA.
    Schubert, Mathias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, USA.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Cavity-enhanced optical Hall effect in epitaxial graphene detected at terahertz frequencies2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, s. 357-360Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cavity-enhanced optical Hall effect at terahertz (THz) frequencies is employed to determine the free charge carrier properties in epitaxial graphene (EG) with different number of layers grown by high-temperature sublimation on 4H-SiC(0001). We find that one monolayer (ML) EG possesses p-type conductivity with a free hole concentration in the low 1012 cmᅵᅵᅵ2 range and a free hole mobility parameter as high as 1550 cm2/Vs. We also find that 6 ML EG shows n-type doping behavior with a much lower free electron mobility parameter of 470 cm2/Vs and an order of magnitude higher free electron density in the low 1013 cmᅵᅵᅵ2 range. The observed differences are discussed. The cavity-enhanced THz optical Hall effect is demonstrated to be an excellent tool for contactless access to the type of free charge carriers and their properties in two-dimensional materials such as EG.

  • 4.
    Azina, Clio
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Tunca, Bensu
    Katholieke Univ Leuven, Belgium.
    Petruhins, Andrejs
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Xin, Binbin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Yildizhan Özyar, Melike
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Vleugels, Jozef
    Katholieke Univ Leuven, Belgium.
    Lambrinou, Konstantina
    SCK CEN, Belgium; Univ Huddersfield, England.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Deposition of MAX phase-containing thin films from a (Ti,Zr)(2)AlC compound target2021Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 551, artikkel-id 149370Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work reports on sputter depositions carried out from a compound (Ti,Zr)(2)AlC target on Al2O3(0 0 0 1) substrates at temperatures ranging between 500 and 900 degrees C. Short deposition times yielded 30-40 nm-thick Al-containing (Ti,Zr)C films, whereas longer depositions yielded thicker films up to 90 nm which contained (Ti,Zr)C and intermetallics. At 900 degrees C, the longer depositions led to films that also consisted of solid solution MAX phases. Detailed transmission electron microscopy showed that both (Ti,Zr)(2)AlC and (Ti,Zr)(3)AlC2 solid solution MAX phases were formed. Moreover, this work discusses the growth mechanism of the thicker films, which started with the formation of the mixed (Ti,Zr)C carbide, followed by the nucleation and growth of aluminides, eventually leading to solid state diffusion of Al within the carbide, at the highest temperature (900 degrees C) to form the MAX phases.

    Fulltekst (pdf)
    fulltext
  • 5.
    Bafekry, A.
    et al.
    Univ Guilan, Iran; Islamic Azad Univ, Iran.
    Faraji, M.
    TOBB Univ Econ & Technol, Turkey.
    Fadlallah, Mohamed M.
    Benha Univ, Egypt.
    Jappor, H. R.
    Univ Babylon, Iraq.
    Hieu, N. N.
    Duy Tan Univ, Vietnam; Duy Tan Univ, Vietnam.
    Ghergherehchi, M.
    Sungkyunkwan Univ, South Korea.
    Gogova-Petrova, Daniela
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ab-initio-driven prediction of puckered penta-like PdPSeX (X=O, S, Te) Janus monolayers: Study on the electronic, optical, mechanical and photocatalytic properties2022Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 582, artikkel-id 152356Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A systematic investigation of the structural, mechanical, electronic, and optical properties of puckered penta-like PdPSeX (X=O, S and Te) Janus monolayers has been performed by means of the plane wave density functional theory. It is confirmed that the pentagonal PdPSeX monolayers are dynamically and mechanical stable by means of analysis of their phonon dispersion curves and the Born condition under harmonic approximation, respectively. The PdPSeX Janus monolayers are disclosed as brittle two-dimensional materials (2DMs). The PBE (HSE06)-based calculations exhibit they are indirect semiconductors with bandgap values of 0.65 (1.44) eV, 1.20 (2.02) eV, and 0.98 (1.70) eV for PbPSeO, PbPSeS, and PbPSeTe monolayer, sequentially. The computational results demonstrate the PdPSeTe monolayer as the best suited candidate for visible light absorption and photocatalytic water splitting within the considered pentagonal PdPSeX monolayers. Our ab-initio-based outcomes provide an insight into the fundamental properties of the penta-like PdPSeX Janus structures and surely would motivate further experimental and theoretical studies to reveal the full application potential of this new type of 2DMs.

    Fulltekst (pdf)
    fulltext
  • 6.
    Bafekry, A.
    et al.
    Univ Guilan, Iran; Islamic Azad Univ, Iran.
    Faraji, M.
    TOBB Univ Econ & Technol, Turkey.
    Hieu, N. N.
    Duy Tan Univ, Vietnam; Duy Tan Univ, Vietnam.
    Khatibani, A. Bagheri
    Islamic Azad Univ, Iran.
    Fadlallah, Mohamed M.
    Benha Univ, Egypt.
    Gogova-Petrova, Daniela
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ghergherehchi, M.
    Sungkyunkwan Univ, South Korea.
    Tunable electronic properties of porous graphitic carbon nitride (C6N7) monolayer by atomic doping and embedding: A first-principle study2022Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 583, artikkel-id 152270Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Motivated by the successful synthesis of the porous graphitic carbon nitride (C6N7) monolayer very recently, we investigate the structural and electronic properties of C6N7 with doped and embedded with various atoms by means of spin-polarized density functional theory calculations. C6N7 monolayers doped with B, N, C, and O atoms have been revealed as stable and predicted to be feasible for experimental fabrication as free-standing monolayers based on the energy and thermal stability. Our computations demonstrate that while the C6N7 is a semiconductor, the doped C6N7 monolayers can be metal, dilute-magnetic semiconductor or half-metal. Further, a non magnetic moment is discovered in three of the doped C6N7 models and their electronic properties are disclosed to depend strongly on the spin configurations. The electronic properties of C6N7 depend on the doping atoms and doping sites. Furthermore, the effect of embedding of common nonmetal atoms such as B, C, N, S, O, Al, Si and P as well as transition metal including Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn atoms on the electronic and magnetic behavior of the C6N7 are studied. The charge transfer analysis shows that all embedded atoms act as electron donors, expect N, O and S atoms which act as electron acceptors when interacting with C6N7. The modification of the electronic band structure of C6N7 as the underlying mechanism for the changes in its electronic properties has been investigated. The intention is to demonstrate how entering the above mentioned impurities changes the nature of C6N7 into a metal, ferromagnetic-metal or dilute-magnetic semiconductor. These findings give not only an insight into the physical properties of doped and embedded C6N7 monolayer by different atoms, but also can serve as a guide to discover future possible applications of this novel material.

  • 7.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Dorri, Samira
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Kosari, Ali
    Delft Univ Technol, Netherlands.
    Mol, Arjan
    Delft Univ Technol, Netherlands.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Microstructure, mechanical, and corrosion properties of Zr1-xCrxBy diboride alloy thin films grown by hybrid high power impulse/DC magnetron co-sputtering2022Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 591, artikkel-id 153164Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study microstructure, mechanical, and corrosion properties of Zr1-xCrxBy coatings deposited by hybrid high power impulse/DC magnetron co-sputtering (CrB2-HiPIMS/ZrB2-DCMS). Cr/(Zr + Cr) ratio, x, increases from 0.13 to 0.9, while B/(Zr + Cr) ratio, y, decreases from 2.92 to 1.81. As reference, ZrB2.18 and CrB1.81 layers are grown at 4000 W DCMS. ZrB2.18 and CrB1.81 columns are continual from near substrate toward the surface with open column boundaries. We find that the critical growth parameter to achieve dense films is the ratio of Cr+- dominated ion flux and the (Zr + B) neutral flux from the ZrB2 target. Thus, the alloys are categorized in two groups: films with x < 0.32 (low Cr+/(Zr + B) ratios) that have continuous columnar growth, rough surfaces, and open column boundaries, and films with x >= 0.32 (high Cr+/(Zr + B) ratios) that Cr+-dominated ion fluxes are sufficient to interrupt continuous columns, resulting in smooth surface and dense fine-grain microstructure. The pulsed metal-ion irradiation is more effective in film densification than continuous Ar+ bombardment. Dense Zr0.46Cr0.54B2.40 and Zr0.10Cr0.90B1.81 alloys are hard (> 30 GPa) and almost stress-free with relative nano indentation toughness of 1.3 MPa root m and 2.3 MPa root m, respectively, and remarkedly low corrosion rates (~& nbsp;1.0 x 10(-6) mA/cm(2) for Zr0.46Cr0.54B2.40 and~& nbsp; 2.1 x 10(-6) mA/cm(2) for Zr0.10Cr0.90B1.81).

    Fulltekst (pdf)
    fulltext
  • 8.
    Bertuccio, Giuseppe
    et al.
    Politecnico di Milano, Como Campus, Italy.
    Puglisi, Donatella
    Politecnico di Milano, Como Campus, Italy.
    Torrisi, Lorenzo
    University of Messina, Italy.
    Lanzieri, Claudio
    Selex Sistemi Integrati S.p.A., Rome, Italy.
    Silicon carbide detector for laser-generated plasma radiation2013Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 272, s. 128-131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the performance of a Silicon Carbide (SiC) detector in the acquisition of the radiation emittedby laser generated plasmas. The detector has been employed in time of flight (TOF) configuration withinan experiment performed at the Prague Asterix Laser System (PALS). The detector is a 5 mm2 area 100 nmthick circular Ni SiC Schottky junction on a high purity 4H-SiC epitaxial layer 115 μm thick. Currentsignals from the detector with amplitudes up to 1.6 A have been measured, achieving voltage signals over 80 V on a 50 Ω load resistance with excellent signal to noise ratios. Resolution of few nanoseconds hasbeen experimentally demonstrated in TOF measurements. The detector has operated at 250 V DC biasunder extreme operating conditions with no observable performance degradation.

  • 9.
    Bjorklund, Robert
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Karlsson, Susanne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Borén, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Organisk Analytisk Kemi.
    Allard, E
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Linkoping Univ, Dept Water & Environm Studies, S-58183 Linkoping, Sweden.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Photodesorption of fulvic acid from iron oxide surfaces into aqueous solutions2001Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 174, nr 2, s. 166-175Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photodesorption of thin films of fulvic acid adsorbed on planar iron oxide surfaces was monitored by ellipsometry. Description was first observed at 546 nm, and additional fractions of the adsorbed acid left the surfaces at 405 and 365 nm Similar kinetics for photodesorption was observed from metallic iron films and from porous iron oxide prepared electrochemically by deposition on porous silicon substrates. Soluble photoproducts leaving the surface H ere monitored by UV absorbance spectroscopy at 200 nm Gaseous products were not detected by mass spectrometry but the results seemed to indicate that net all of the photoproducts entered the liquid phase. Of the metal films tested which adsorbed fulvic acid from aqueous solution (Fe. Cr, Ni, Al, and Pt), it was only iron which exhibited a photodesorption effect. (C) 2001 Elsevier Science B.V. All rights reserved.

  • 10.
    Briley, Chad
    et al.
    University of Nebraska, NE 68588 USA.
    Mock, Alyssa
    University of Nebraska, NE 68588 USA.
    Korlacki, Rafal
    University of Nebraska, NE 68588 USA.
    Hofmann, Tino
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. University of Nebraska, NE 68588 USA.
    Schubert, Eva
    University of Nebraska, NE 68588 USA.
    Schubert, Mathias
    University of Nebraska, NE 68588 USA.
    Effects of annealing and conformal alumina passivation on anisotropy and hysteresis of magneto-optical properties of cobalt slanted columnar thin films2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, s. 320-324Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present magneto-optical dielectric tensor data of cobalt and cobalt oxide slanted columnar thin films obtained by vector magneto-optical generalized ellipsometry. Room-temperature hysteresis magnetization measurements were performed in longitudinal and polar Kerr geometries on samples prior to and after a heat treatment process with and without a conformal Al2O3 passivation coating. The samples have been characterized by generalized ellipsometry, scanning electron microscopy, and Raman spectroscopy in conjuncture with density functional theory. We observe strongly anisotropic hysteresis behaviors, which depend on the nanocolumn and magnetizing field orientations. We find that deposited cobalt films that have been exposed to heat treatment and subsequent atmospheric oxidation into Co3O4, when not conformally passivated, reveal no measurable magneto-optical properties while cobalt films with passivation coatings retain highly anisotropic magneto-optical properties (C) 2016 Published by Elsevier B.V.

  • 11.
    Bukaluk, A.
    et al.
    Instytut Matematyki I Fizyki, Akademia Techniczno-Rolnicza, Ul. K., Bydgoszcz, Poland.
    Wronkowska, A.A.
    Instytut Matematyki I Fizyki, Akademia Techniczno-Rolnicza, Ul. K., Bydgoszcz, Poland.
    Wronkowski, A.
    Instytut Matematyki I Fizyki, Akademia Techniczno-Rolnicza, Ul. K., Bydgoszcz, Poland.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Firszt, F.
    Instytut Fizyki, Uniw. Mikolaja Kopernika, Ul. G., Torun, Poland.
    Legowski, S.
    Instytut Fizyki, Uniw. Mikolaja Kopernika, Ul. G., Torun, Poland.
    Meczynska, H.
    Meczynska, H., Instytut Fizyki, Uniw. Mikolaja Kopernika, Ul. G., Torun, Poland.
    Szatkowski, J.
    Instytut Fizyki, Uniw. Mikolaja Kopernika, Ul. G., Torun, Poland.
    Auger electron spectroscopy, ellipsometry and photoluminescence investigations of Zn1-XBeXSe alloys2001Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 175-176, s. 531-537Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, properties of the Zn1-XBeXSe crystals grown from the melt by the high-pressure Bridgman method are reported. Spectroscopic ellipsometry has been used for determination of the complex dielectric function of Zn1-XBeXSe. On the basis of the photon energy dependence of the dielectric function, the energy gaps of alloys containing different beryllium concentrations have been evaluated. Measurements of the photoluminescence (PL) spectra allowed to find the excitonic gap in the investigated alloys. Auger electron spectroscopy (AES) with simultaneous argon ion sputtering has been used for determination of surface composition. AES investigations allowed to make predictions concerning distribution of particular elements in the samples. © 2001 Elsevier Science B.V.

  • 12.
    Chen, Ruei-San
    et al.
    National Taiwan University of Science and Technology, Taiwan.
    Tang, Chih-Che
    Department of Electronic Engineering, National Taiwan University of Science and Technology, Taiwan.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Holtz, Per Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Electronic transport properties in aluminum indium nitride nanorods grown by magnetron sputter epitaxy2013Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 285, s. 625-628Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electronic transport properties of the wide-bandgap aluminum indium nitride (AlInN) nanorods (NRs) grown by ultrahigh-vacuum magnetron sputter epitaxy (MSE) have been studied. The conductivities of the ternary compound nanostructure locates at the value of 15 Q-1 cm -1, which is respectively one and two orders of magnitude lower than the binary GaN and InN counterparts grown by chemical vapor deposition (CVD). The very shallow donor level/band with the activation energy at 11 + 2 meV was obtained by the temperature-dependent measurement. In addition, the photoconductivity has also been investigated. The photoconductive (PC) gain of the NRs device can reach near 2400 under a low bias at 0.1 V and the light intensity at 100W m-2 for ultraviolet response in vacuum. The power-insensitive gain and ambience-dependent photocurrent are also observed, which is attributed to the probable surfacecontrolled PC mechanism in this ternary nitride nanostructure.

    Fulltekst (pdf)
    fulltext
  • 13.
    Dannetun, Helen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Lundström, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Petersson, L.-G.
    The relative ionization gauge sensitivity of some unsaturated hydrocarbons1987Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 29, s. 331-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By studying the water desorption rate from an oxygen covered Pd surface which is exposed to some unsaturated hydrocarbons (and hydrogen) the relative ionization gauge sensitivity of the hydrocarbons: acetylene, ethylene, propene, 1- and 2-butene, propadiene, 1,3-butadiene, propyne and butyne has been determined.

  • 14.
    Dannetun, Helen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Petersson, L.-G.
    Söderberg, D.
    Lundström, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    A hydrogen-sensitive Pd-MOS structure working over a wide pressure range1984Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 17, s. 259-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A Pd-MOS structure has been developed which has proven to be sensitive to hydrogen both in air at atmospheric pressures and in UHV. The ability to work over a wide pressure range makes it an interesting component in, e.g., the study of catalytic reactions involving hydrogen on metal surfaces. Here we demonstrate the hydrogen sensitivity of such a structure over a pressure range of 5x10-11 to 2 Torr.

  • 15.
    Dorri, Samira
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Stendahl, Sjoerd
    Department of Physics and Astronomy, Material Physics, Uppsala University, Uppsala, Sweden.
    Devishvili, Anton
    Institut Laue-Langevin, Grenoble, France.
    Vorobiev, Alexei
    Department of Physics and Astronomy, Material Physics, Uppsala University, Uppsala, Sweden; Institut Laue-Langevin, Grenoble, France .
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O.Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Enhanced quality of single crystal CrBx/TiBy diboride superlattices by controlling boron stoichiometry during sputter deposition2024Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, artikkel-id 159606Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Single-crystal CrB2/TiB2 diboride superlattices with well-defined layers are promising candidates for neutron optics. However, excess B in sputter-deposited TiBy using a single TiB2 target deteriorates the structural quality of CrBx/TiBy (0001) superlattices. We study the influence of co-sputtering of TiB2 + Ti on the stoichiometry and crystalline quality of 300-nm-thick TiBy single layers and CrBx/TiBy (0001) superlattices on Al2O3(0001) substrates grown by DC magnetron sputter epitaxy at growth-temperatures TS ranging from 600 to 900 °C. By controlling the relative applied powers to the TiB2 and Ti magnetrons, y could be reduced from 3.3 to 0.9. TiB2.3 grown at 750 °C exhibited epitaxial domains about 10x larger than non-co-sputtered films. Close-to-stoichiometry CrB1.7/TiB2.3 superlattices with modulation periods Λ = 6 nm grown at 750 °C showed the highest single crystal quality and best layer definition. TiB2.3 layers display rough top interfaces indicating kinetically limited growth while CrB1.7 forms flat and abrupt top interfaces indicating epitaxial growth with high adatom mobility.

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  • 16.
    Eriksson, Mats
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Real time measurements of hydrogen desorption and absorption during CO exposures of Pd: Hydrogen sticking and dissolution1998Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 133, nr 1-2, s. 89-97Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Combined real time measurements of hydrogen desorption and absorption show that both processes may be induced simultaneously by CO adsorption on a hydrogen-covered Pd surface. The induced absorption is found to be a kinetic effect, where the amount absorbed depends on the hydrogen desorption rate and the CO adsorption rate. In addition to simple site blocking, adsorbed CO induces an increase in the hydrogen desorption energy and an activation barrier for hydrogen dissociation. Both increase linearly with CO coverage for θCO>0.18 ML. Below this coverage, the hydrogen dissociation is non-activated.

  • 17.
    Gangaprasad Rao, Smita
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Shu, Rui
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och ytbeläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Le Febvrier, Arnaud
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    The effects of copper addition on phase composition in (CrFeCo)1-yNy multicomponent thin films2022Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 572, artikkel-id 151315Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Cantor alloy CrFeCoMnNi is generally fcc structured, but moderate changes in the composition can have a large influence on the phase formation. The aim of this study was to understand the changes brought on in lownitrogen-containing (CrFeCo)1-yNy thin films with y = 0.19 on the addition of copper, an interesting metal in terms of atomic size and nitride formation enthalpy. (CrFeCoCux)1-yNy films were grown by reactive magnetron sputtering. The amount of copper in the films was increased from x = 0 to x = 0.15 to study competitive phase formation. Without Cu, two-phase fcc + bcc films were obtained. The addition of Cu was found to stabilize the bcc structure despite the fact that Cu as a pure metal is fcc. Nanoindentation tests showed slight increase in hardness with initial Cu addition from 11 GPa to 13.7 +/- 0.2 GPa. The occurrence of pile up as opposed to cracking is an indication of the films ductility.

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  • 18.
    Gervacio-Arciniega, J. J.
    et al.
    University of Nacl Autonoma Mexico, Mexico.
    Flores-Ruiz, F. J.
    University of Nacl Autonoma Mexico, Mexico.
    Diliegros-Godines, C. J.
    University of Nacl Autonoma Mexico, Mexico.
    Broitman, Esteban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Enriquez-Flores, C. I.
    CINVESTAV, Mexico.
    Espinoza-Beltran, F. J.
    CINVESTAV, Mexico.
    Siqueiros, J.
    University of Nacl Autonoma Mexico, Mexico.
    Cruz, M. P.
    University of Nacl Autonoma Mexico, Mexico.
    Nanofrictional behavior of amorphous, polycrystalline and textured Y-Cr-O films2016Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 378, s. 157-162Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Differences in friction coefficients (mu) of ferroelectric YCrO3, textured and polycrystalline films, and non-ferroelectric Y-Cr-O films are analyzed. The friction coefficient was evaluated by atomic force microscopy using a simple quantitative procedure where the dependence of friction force with the applied load is obtained in only one topographical image. A simple code was developed with the MATLAB (R) software to analyze the experimental data. The code includes a correction of the hysteresis in the forward and backward scanning directions. The quantification of load exerted on the sample surface was obtained by finite element analysis of the AFM cantilever starting from its experimental dynamic information. The results show that the ferroelectric YCrO3 film deposited on a Pt(150 nm)/TiO2(30 nm)/SiO2/Si (100) substrate is polycrystalline and has a lower friction coefficient than the deposited on SrTiO3 (110), which is highly textured. From a viewpoint of industrial application in ferroelectric memories, where the writing process is electrical or mechanically achieved by sliding AFM tips on the sample, polycrystalline YCrO3 films seem to be the best candidates due to their lower mu, (C) 2016 Elsevier B.V. All rights reserved.

  • 19.
    Gervilla Palomar, Victor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten.
    Almyras, Georgios
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten.
    Thunstrom, F.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA.
    Sarakinos, Kostas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten.
    Dynamics of 3D-island growth on weakly-interacting substrates2019Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 488, s. 383-390Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The growth dynamics of faceted three-dimensional (3D) Ag islands on weakly-interacting substrates are investigated-using kinetic Monte Carlo (kMC) simulations and analytical modelling-with the objective of determining the critical top-layer radius R-c required to nucleate a new island layer as a function of temperature T, at a constant deposition rate. kMC shows that R-c decreases from 17.3 to 6.0 angstrom as T is increased at 25 K intervals, from 300 to 500 K. That is, a higher T promotes top-layer nucleation resulting in an increase in island height-to-radius aspect ratios. This explains experimental observations for film growth on weakly-interacting substrates, which are not consistent with classical homoepitaxial growth theory. In the latter case, higher temperatures yield lower top-layer nucleation rates and lead to a decrease in island aspect ratios. The kMC simulation results are corroborated by an analytical mean field model, in which R-c is estimated by calculating the steady-state adatom density on the island side facets and top layer as a function of T. The overall findings of this study constitute a first step toward developing rigorous theoretical models, which can be used to guide synthesis of metal nanostructures, and layers with controlled shape and morphology, on technologically important substrates, including two-dimensional crystals, for nanoelectronic and catalytic applications.

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  • 20. Greczynski, G.
    et al.
    Fahlman, Mats
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi.
    Salaneck, William R
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi.
    Experimental study of poly(9,9-dioctyl-fluorene) and its interface with Li and LiF2000Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 166, nr 1, s. 380-386Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chemical and electronic structure of a new conjugated polymer, poly(9,9-dioctyl-fluorene) (PFO), has been studied by photoelectron spectroscopy. The polymer films were free of oxygen contamination (within the detection limits of photoelectron spectroscopy). X-ray and ultraviolet photoelectron spectroscopy was carried out on Li- and LiF-deposition on PFO as well as on LiF-deposition on aluminum. In the case of Li-deposition on PFO films, doping occurred resulting in the formation of polaronic charge carriers at low doping levels and bipolaronic charge carriers at high doping levels. LiF-deposition on PFO did not cause doping of the polymer films, nor did the LiF dissociate at the interface. No significant shifts in binding energy (BE) or work function occurred. LiF-deposition on sputter-cleaned aluminum showed evidence of surface dipole formation, though LiF dissociation was not detected. Al-deposition on LiF/PFO films did not cause dissociation of LiF, unlike the case in Alq3.

  • 21. Greczynski, G.
    et al.
    Salaneck, William R
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi.
    Fahlman, Mats
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi.
    An experimental study of poly(9,9-dioctyl-fluorene) and its interfaces with Al, LiF and CsF2001Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 175-176, s. 319-325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sandwich-style interfaces of Al/LiF/poly(9,9-dioctyl-fluorene) and Al/CsF/poly(9,9-dioctyl-fluorene) have been studied using X-ray and ultraviolet photoelectron spectroscopy. The polymer films were free of oxygen contamination (within the detection limits of photoelectron spectroscopy). In the case of LiF-deposition on poly(9,9-dioctyl-fluorene) films, doping did not occur, nor did the LiF dissociate upon Al-deposition. No significant shifts in a binding energy of the core levels, nor any changes in the work function were detected. However, for the Al/LiF/poly(9,9-dioctyl-fluorene) interface, there was no degradation of the p-electronic structure, unlike the case for Al deposited directly unto poly(9,9-dioctyl-fluorene). For the Al/CsF/poly(9,9-dioctyl-fluorene) interface, the CsF dissociated upon Al-deposition, with the Cs likely n-doping, the polymer at the interface. When deposited onto an Al surface, CsF also were found to dissociate at the interface but remaining in the CsF form away from the Al surface. © 2001 Elsevier Science B.V.

  • 22.
    Greczynski, Grzegorz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Critical method evaluation refutes the Ar 2p signal of implanted Ar for referencing X-ray photoelectron spectra2023Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 635, artikkel-id 157598Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Correct binding energy (BE) spectra referencing of insulating samples remains the major challenge in modern XPS analyses. Ar 2p signal of implanted Ar is sometimes used for this purpose. The method relies upon the assumption that chemically inert species such as noble gas atoms would be ideally suited as other factors affecting core level peak positions (such as chemical bonding) can be excluded. Here, we present a systematic study on the Ar 2p referencing method applied to a wide range of thin film sample materials of metals, nitrides, carbides, and borides. All specimens exhibit a well-defined Fermi edge, which serves as an independent internal reference for Ar 2p spectra of in-situ implanted Ar. Ar 2p3/2 binding energy is shown to vary by as much as 5.1 eV between samples. This is more than typical chemical shifts of interest, which obviously disqualifies Ar 2p referencing. The BE of the Ar 2p peaks shows a strong correlation to the number of valence electrons available for screening, implying that the polarization energy has a major role for the observed large spread of Ar 2p3/2 BE values. In several cases of single-phase films, an additional Ar 2p doublet is observed with the Ar 2p3/2 BE referenced to the vacuum level higher than the gas phase value of 248.6 eV, which is tentatively assigned to the formation of Ar-N and Ar-C complexes stabilized by Van der Waals forces. Ar implantation into two-phase samples, exemplified here by phase-segregated NiCrC/a-C:H and nanocomposite c-TiN/SiNx thin films, leads to complex Ar 2p spectra, which further demonstrates unreliability of the referencing method. The firm conclusion of the study is that the Ar 2p3/2 peak from implanted Ar is not a remedy for the charge referencing problem.

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  • 23.
    Greczynski, Grzegorz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Referencing to adventitious carbon in X-ray photoelectron spectroscopy: Can differential charging explain C 1s peak shifts?2022Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 606, artikkel-id 154855Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    C 1s peak of adventitious carbon (AdC), often used for charge referencing XPS spectra, shows markedly large shifts from the "recommended" value of 284.8 eV that basically disqualifies its reliability. In some earlier papers we attributed this spreading effect to the vacuum level (VL) alignment at the AdC/sample interface, which makes the measured position of C 1s peak highly sensitive to the sample work function . Recently, it was suggested [M.C. Biesinger, Appl. Surf. Sci. 597 (2022) 153681] that it is instead the differential charging in the native oxide layers that sometimes accounts for C 1s shifts and that electrically isolating samples from the spectrometer would solve the problem. To evaluate this hypothesis, we performed a series of experiments with Au and Al foils electrically isolated from the spectrometer, while varying the surface potential in a relatively wide range by adjusting the charge neutralizer settings. Markedly, the C 1s peak positions recorded from Au and Al foils are distinctly different when referred to their Fermi levels, at respectively 284.80 +/- 0.05 eV and 286.31 +/- 0.06 eV, independent of the surface potential. This confirms the interpretation presented in our previous papers (experiments performed in a conventional way with samples connected to spectrometer), that the binding energy of C 1s peaks from Au and Al foils differs significantly due to the corresponding difference in their work function values, such that the sum is constant at similar to 289.6 eV, as imposed by the VL alignment. In addition, the energy separation between metal and oxide peaks in Al 2p spectra from Al foil is independent of the surface potential (controlled by the charge neutralizer settings), the photoelectron current (varied by adjusting x-ray power) and the Al oxide thickness (in the range from 0.7 to 4.7 nm). These observations disprove differential charging as the general cause of C 1s peak shifts at least for the case of Al foils with thinner oxide layers. As many thicker oxides are well-known to develop charging, a similar type of analysis can be performed on the case-tocase bases to determine the reasons for C 1s peak shifts.

    Fulltekst (pdf)
    fulltext
  • 24.
    Greczynski, Grzegorz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Reliable determination of chemical state in x-ray photoelectron spectroscopy based on sample-work-function referencing to adventitious carbon: Resolving the myth of apparent constant binding energy of the C 1s peak2018Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 451, s. 99-103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The accuracy of chemical-state determination by x-ray photoelectron spectroscopy (XPS) used in contemporary advanced materials research relies on a trustworthy binding energy (BE) referencing method. The C 1s peak corresponding to C-C/C-H bonds of adventitious carbon (AdC), present on a majority of air-exposed samples, is most commonly employed for this purpose, irrespective of whether samples are electrically conducting or not. Contrary to conventional practice, which takes the BE of C 1s peak of AdC as a constant, we find that the C 1s peak position E-B(F) varies over an alarmingly large range, from 284.08 to 286.74 eV, depending on the substrate, for nearly a hundred predominantly thin-film samples comprising metals, nitrides, carbides, borides, oxides, and oxynitrides. Our consistent measurements also show that, independent of materials system, E-B(F) of the C 1s peak is closely correlated to the sample work function phi(SA),such that the sum E-B(F) thorn /SA is constant, indicating that the electronic levels of the AdC layer align to the vacuum level, rather than to the Fermi level as commonly assumed. This phenomenon can be understood given that the AdC layer is not an inherent part of the analyzed sample and that the interaction to the substrate is weak, showing in that a common Fermi level is not established at the interface. Thus, a straightforward complementary measurement of /SA enables using the C 1s peak of AdC for the purpose of BE-scale calibration for samples exhibiting decent electrical conductivity. This new practice resolves problems associated with the conventional method and allows for more reliable bonding assignments. It is thus advisable that both ASTM and ISO XPS referencing guides relying on the use of AdC should be reviewed. (C) 2018 Elsevier B.V. All rights reserved.

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  • 25.
    Greczynski, Grzegorz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Self-consistent modelling of X-ray photoelectron spectra from air-exposed polycrystalline TiN thin films2016Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 387, s. 294-300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present first self-consistent modelling of x-ray photoelectron spectroscopy (XPS) Ti 2p, N ls, 0 ls, and C ls core level spectra with a cross-peak quantitative agreement for a series of TiN thin films grown by dc magnetron sputtering and oxidized to different extent by varying the venting temperature Tv of the vacuum chamber before removing the deposited samples. So-obtained film series constitute a model case for XPS application studies, where certain degree of atmosphere exposure during sample transfer to the XPS instrument is unavoidable. The challenge is to extract information about surface chemistry without invoking destructive pre-cleaning with noble gas ions. All TiN surfaces are thus analyzed in the as-received state by XPS using monochromatic Al K alpha. radiation (hv = 1486.6 eV). Details of line shapes and relative peak areas obtained from deconvolution of the reference Ti 2p and N 1 s spectra representative of a native TiN surface serve as an input to model complex core level signals from air-exposed surfaces, where contributions from oxides and oxynitrides make the task very challenging considering the influence of the whole deposition process at hand. The essential part of the presented approach is that the deconvolution process is not only guided by the comparison to the reference binding energy values that often show large spread, but in order to increase reliability of the extracted chemical information the requirement for both qualitative and quantitative self-consistency between component peaks belonging to the same chemical species is imposed across all core-level spectra (including often neglected 0 is and C is signals). The relative ratios between contributions from different chemical species vary as a function of T-v presenting a self-consistency check for our model. We propose that the cross-peak self-consistency should be a prerequisite for reliable XPS peak modelling as it enhances credibility of obtained chemical information, while relying entirely on reference binding energy values introduces large ambiguity. (C) 2016 Elsevier B.V. All rights reserved.

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  • 26.
    Greczynski, Grzegorz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Towards reliable X-ray photoelectron spectroscopy: Sputter-damage effects in transition metal borides, carbides, nitrides, and oxides2021Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 542, artikkel-id 148599Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ar+ sputter etching is often used prior to X-ray photoelectron spectroscopy (XPS) analyses with the intention to remove surface oxides and contaminants. Since the XPS probing depth is comparable to the thickness of the ionbeam modified layer the signal from the latter dominates the spectra. We check here the conditions for reliable XPS analysis by studying ion irradiation effects for single-phase Group IVB transition metal (IVB-TM) boride, carbide, nitride, and oxide thin film specimens. The extent of sputter damage, manifested by changes in the surface composition, binding energy shift, peak broadening, and the appearance of new spectral features, varies greatly between material systems: from subtle effects in the case of IVB-TM carbides to a complete change of spectral components for IVB-TM oxides. The determining factors are: (i) the nature of compounds that may form as a result of ion-induced mixing in the affected layer together with (ii) the final elemental composition after sputtering, and (iii) the thickness of the Ar+-affected layer with respect to the XPS probing depth. Our results reveal that the effects of Ar+ ion irradiation on XPS spectra cannot be a priori neglected and a great deal of scrutiny, if not restraint, is necessary during spectra interpretation.

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  • 27.
    Greczynski, Grzegorz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Rhein Westfal TH Aachen, Germany.
    Mraz, S.
    Rhein Westfal TH Aachen, Germany.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Schneider, J. M.
    Rhein Westfal TH Aachen, Germany.
    Unintentional carbide formation evidenced during high-vacuum magnetron sputtering of transition metal nitride thin films2016Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 385, s. 356-359Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbide signatures are ubiquitous in the surface analyses of industrially sputter-deposited transition metal nitride thin films grown with carbon-less source materials in typical high-vacuum systems. We use high-energy-resolution photoelectron spectroscopy to reveal details of carbon temporal chemical state evolution, from carbide formed during film growth to adventitious carbon adsorbed upon contact with air. Using in-situ grown Al capping layers that protect the as-deposited transition metal nitride surfaces from oxidation, it is shown that the carbide forms during film growth rather than as a result of post deposition atmosphere exposure. The XPS signature of carbides is masked by the presence of adventitious carbon contamination, appearing as soon as samples are exposed to atmosphere, and eventually disappears after one week-long storage in lab atmosphere. The concentration of carbon assigned to carbide species varies from 0.28 at% for ZrN sample, to 0.25 and 0.11 at% for TiN and HfN, respectively. These findings are relevant for numerous applications, as unintentionally formed impurity phases may dramatically alter catalytic activity, charge transport and mechanical properties by offsetting the onset of thermally induced phase transitions. Therefore, the chemical state of C impurities in PVD-grown films should be carefully investigated. (C) 2016 Elsevier B.V. All rights reserved.

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  • 28.
    Greczynski, Grzegorz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Primetzhofer, D.
    Uppsala Univ, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Reference binding energies of transition metal carbides by core-level x-ray photoelectron spectroscopy free from Ar+ etching artefacts2018Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 436, s. 102-110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report x-ray photoelectron spectroscopy (XPS) core level binding energies (BEs) 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. (C) 2017 Elsevier B.V. All rights reserved.

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  • 29.
    Greczynski, Grzegorz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Primetzhofer, D.
    Uppsala University, Sweden.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Core-level spectra and binding energies of transition metal nitrides by non-destructive x-ray photoelectron spectroscopy through capping layers2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 396, s. 347-358Artikkel i tidsskrift (Fagfellevurdert)
    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 (TMNs) 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 TMNs 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. (C) 2016 Elsevier B. V. All rights reserved.

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  • 30.
    Gurban, S.
    et al.
    Hungarian Academic Science, Hungary.
    Pecz, B.
    Hungarian Academic Science, Hungary.
    Menyhard, M.
    Hungarian Academic Science, Hungary.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Determination of the thickness distribution of a graphene layer grown on a 2 SiC wafer by means of Auger electron spectroscopy depth profiling2014Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 316, s. 301-307Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Auger electron spectroscopy (AES) depth profiling was applied for determination of the thickness of a macroscopic size graphene sheet grown on 2 in. 6H-SiC (0 0 0 1) by sublimation epitaxy. The measured depth profile deviated from the expected exponential form showing the presence of an additional, buffer layer. The measured depth profile was compared to the simulated one which allowed the derivation of the thicknesses of the graphene and buffer layers and the Si concentration of buffer layer. It has been shown that the graphene-like buffer layer contains about 30% unsaturated Si. The depth profiling was carried out in several points (diameter 50 mu m), which permitted the constructing of a thickness distribution characterizing the uniformity of the graphene sheet.

  • 31.
    Halim, Joseph
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Cook, Kevin M.
    Praxair Inc, NY 14150 USA.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Barsoum, Michel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Drexel Univ, PA 19104 USA.
    XPS of cold pressed multilayered and freestanding delaminated 2D thin films of Mo2TiC2Tz and Mo2Ti2C3Tz (MXenes)2019Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 494, s. 1138-1147Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    MXenes, transition metal carbides and/or nitrides, that are synthesized from the top down by etching of their 3D parent layered solids, the MAX phases, are the latest family of the two-dimensional solids discovered. When the A layers - mostly Al - are etched they are replaced by surface terminations, Tz mainly comprised of O-, OH- and F-terminations. One of the few techniques capable of quantifying these surface terminations is X-ray photo-electron spectroscopy, XPS. Herein, we undertook an XPS study of the out-of-plane ordered MXenes, Mo2TiC2Tz and Mo2Ti2C3Tz, in both multilayered, ML, cold pressed and delaminated thin film forms. The harsh conditions needed to etch these MAX phases into MLs, results in their partial oxidation. The hydroxide used to delaminate the MLs results in further oxidation and a reduction in the F-content. In all cases, etching resulted in a decrease in the Ti to Mo ratio implying that the former atoms are selectively etched. In all but the ML Mo2TiC2Tz case, the Mo to C ratio was also reduced. It follows that the loss of Ti also results in the loss of C atoms. Again with the exception of the ML Mo2Ti2C3Tz case, the number of termination moles per formula unit, z, was amp;gt; 2, which is energetically unfavorable and thus unlikely. However, if one assumes that not all of the O signal is coming from terminations but rather from O atoms that replace C atoms in the MX blocks, then z similar to 2. This work is an important step in quantifying and understanding the effects of etching on terminations and structure in these Mo and Ti-based MXenes.

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  • 32.
    Halim, Joseph
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Drexel University, PA 19104 USA; Drexel University, PA 19104 USA.
    Cook, Kevin M.
    Naval Air Syst Command, MD 20670 USA.
    Naguib, Michael
    Oak Ridge National Lab, TN 37831 USA.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Gogotsi, Yury
    Drexel University, PA 19104 USA; Drexel University, PA 19104 USA.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Barsoum, Michel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Department of Materials Science & Engineering, Drexel University, Philadelphia, PA 19104, USA.
    X-ray photoelectron spectroscopy of select multi-layered transition metal carbides (MXenes)2016Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 362, s. 406-417Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, a detailed high resolution X-ray photoelectron spectroscopy (XPS) analysis is presented for select MXenes a recently discovered family of two-dimensional (2D) carbides and carbonitrides. Given their 2D nature, understanding their surface chemistry is paramount. Herein we identify and quantify the surface groups present before, and after, sputter-cleaning as well as freshly prepared vs. aged multi layered cold pressed discs. The nominal compositions of the MXenes studied here are Ti-3 C2Tx,Ti3CNTx, Nb2CTx and Nb4C3Tx where T represents surface groups that this work attempts to quantify. In all the cases, the presence of three surface terminations, O, OH and F, in addition to OH-terminations relatively strongly bonded to H2O molecules, was confirmed. From XPS peak fits, it was possible to establish the average sum of the negative charges of the terminations for the aforementioned MXenes. Based on this work, it is now possible to quantify the nature of the surface terminations. This information can, in turn, be used to better design and tailor these novel 2D materials for various applications. Published by Elsevier B.V.

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  • 33. Hallstedt, J
    et al.
    Suvar, E
    Persson, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Wang, YB
    Radamson, HH
    Growth of high quality epitaxial Si1-x-yGexCy layers by using chemical vapor deposition2004Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 224, nr 01-Apr, s. 46-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The epitaxial quality of non-selective and selective deposition of Si1-x-yGexCy (0 less than or equal to x less than or equal to 0.30, 0 less than or equal to y less than or equal to 0.02) layers has been optimized by using high-resolution reciprocal lattice mapping (HRRLM). The main goal was to incorporate a high amount of substitutional carbon atoms in Si or Si1-xGex matrix without creating defects. The carbon incorporation behavior was explained by chemical and kinetic effects of the reactant gases during epitaxial process. Although high quality epitaxial Si1-yCy layers can be deposited, lower electron mobility compared to Si layers was observed. (C) 2003 Elsevier B.V. All rights reserved.

  • 34.
    He, Jiangping
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Hansson, Göran
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik.
    Uhrberg, Roger
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik.
    Atomic structure of the carbon induced Si(001)c(4x4) surface2006Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, s. 5284-5287Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

       

  • 35.
    Hilfiker, James N.
    et al.
    JA Woollam Co Inc, NE 68508 USA.
    Hale, Jeffrey S.
    JA Woollam Co Inc, NE 68508 USA.
    Herzinger, Craig M.
    JA Woollam Co Inc, NE 68508 USA.
    Tiwald, Tom
    JA Woollam Co Inc, NE 68508 USA.
    Hong, Nina
    JA Woollam Co Inc, NE 68508 USA.
    Schoche, Stefan
    JA Woollam Co Inc, NE 68508 USA.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Estimating depolarization with the Jones matrix quality factor2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, s. 494-499Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mueller matrix (MM) measurements offer the ability to quantify the depolarization capability of a sample. Depolarization can be estimated using terms such as the depolarization index or the average degree of polarization. However, these calculations require measurement of the complete MM. We propose an alternate depolarization metric, termed the Jones matrix quality factor, QJM, which does not require the complete MM. This metric provides a measure of how close, in a least-squares sense, a Jones matrix can be found to the measured Mueller matrix. We demonstrate and compare the use of QJM to other traditional calculations of depolarization for both isotropic and anisotropic depolarizing samples; including nonuniform coatings, anisotropic crystal substrates, and beetle cuticles that exhibit both depolarization and circular diattenuation. (C) 2016 Elsevier B.V. All rights reserved.

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  • 36.
    Hofmann, Tino
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. University of North Carolina Charlotte, NC 28223 USA; University of Nebraska, NE USA.
    Knight, S.
    University of Nebraska, NE USA.
    Sekora, D.
    University of Nebraska, NE USA.
    Schmidt, D.
    University of Nebraska, NE USA.
    Herzinger, C. M.
    JA Woollam Co Inc, NE 68508 USA.
    Woollam, J. A.
    JA Woollam Co Inc, NE 68508 USA.
    Schubert, E.
    University of Nebraska, NE USA.
    Schubert, Mathias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. University of Nebraska, NE USA.
    Screening effects in metal sculptured thin films studied with terahertz Mueller matrix ellipsometry2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, s. 513-517Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The anisotropic optical dielectric functions of a metal (cobalt) slanted columnar thin film deposited by electronbeam glancing angle deposition are reported for the terahertz (THz) frequency domain before and after the slanted columnar thin film was passivated by a conformal alumina coating. A simple effective medium dielectric function homogenization approach which describes isolated, electrically conductive columns rendering the thin film biaxial (orthorhombic) is used to model the observed optical responses. Upon passivating the slanted columnar thin film with a 3 nm thick alumina film an increase of both the real and the imaginary part of the dielectric function for all major polarizability directions is found and attributed to screening effects within the spatially coherent metal nanocolumns. (C) 2016 Elsevier B.V. All rights reserved.

  • 37.
    Horvath, ZJ
    et al.
    Hungarian Acad Sci, Res Inst Tech Phys & Mat Sci, H-1525 Budapest 114, Hungary Linkoping Univ, Dept Phys, S-58183 Linkoping, Sweden.
    Järrendahl, Kenneth
    Linköpings universitet, Tekniska högskolan.
    Adam, M
    Hungarian Acad Sci, Res Inst Tech Phys & Mat Sci, H-1525 Budapest 114, Hungary Linkoping Univ, Dept Phys, S-58183 Linkoping, Sweden.
    Szabo, I
    Hungarian Acad Sci, Res Inst Tech Phys & Mat Sci, H-1525 Budapest 114, Hungary Linkoping Univ, Dept Phys, S-58183 Linkoping, Sweden.
    Van Tuyen, V
    Hungarian Acad Sci, Res Inst Tech Phys & Mat Sci, H-1525 Budapest 114, Hungary Linkoping Univ, Dept Phys, S-58183 Linkoping, Sweden.
    Czigany, Z
    Hungarian Acad Sci, Res Inst Tech Phys & Mat Sci, H-1525 Budapest 114, Hungary Linkoping Univ, Dept Phys, S-58183 Linkoping, Sweden.
    Electrical peculiarities in Al/Si/Ge/... /Ge/Si and Al/SiGe/Si structures2002Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 190, nr 1-4, s. 403-407Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The current-voltage (I-V) and capacitance-voltage (C-V) behaviour of different Si/Ge multilayers and SiGe single layers prepared on p-type Si substrates by magnetron sputtering and annealing, has been studied in the temperature rang, of 80-320 K by using Al Schottky contacts as test structures. Although a significant influence of the microstructure of the Si/Ge multilayers and SiGe layers was obtained on the electrical behaviour of the structures, the structures exhibited similar specific features. (C) 2002 Elsevier Science B.V. All rights reserved.

  • 38.
    Hsu, Tun-Wei
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Kolozsvári, Szilárd
    Plansee Composite Materials GmbH, Lechbruck am See, DE-86983, Germany.
    Polcik, Peter
    Plansee Composite Materials GmbH, Lechbruck am See, DE-86983, Germany.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Dense and hard TiWC protective coatings grown with tungsten ion irradiation using WC-HiPIMS/TiC-DCMS co-sputtering technique without external heating2023Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 618, artikkel-id 156639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Titanium tungsten carbide (TiWC) coatings are deposited by a combined high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) technique. No external heating is applied during deposition phase, instead, the thermally driven adatom mobility is substituted by heavy ion irradiation. DCMS sources equipped with titanium carbide targets provide constant neutral fluxes to establish the predominant coating structures, whereas tungsten carbide target in HiPIMS mode serves as the source of heavy metal-ions. Substrate bias of −60 V is synchronized to W+ ion-rich time domains of HiPIMS pulses to minimize the contribution from working gas ions. The influence of W+ ion flux intensity, controlled by varying peak target current density (JT), on film properties is investigated. X-ray photoelectron spectroscopy reveals the presence of over stoichiometric carbon forming an amorphous phase, the amount of which can be fine-tuned by varying JT. Changes in film composition as a function of JT are explained based on the in-situ ion mass spectroscopy analyses. Dense TiWC coatings by hybrid process exhibit hardness higher than 30 GPa, which are comparable to TiWC films deposited by DCMS with dc substrate bias and external heating. The relative energy consumption in the hybrid process is reduced by 77 % as compared to high-temperature DCMS processing.

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  • 39.
    Höglund, Linda
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik. Linköpings universitet, Tekniska högskolan.
    Petrini, E.
    Acreo AB, Electrum 236, S-164 40 Kista, Sweden.
    Asplund, C.
    Acreo AB, Electrum 236, S-164 40 Kista, Sweden.
    Malm, H.
    Acreo AB, Electrum 236, S-164 40 Kista, Sweden.
    Andersson, J. Y.
    Acreo AB, Electrum 236, S-164 40 Kista, Sweden.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik. Linköpings universitet, Tekniska högskolan.
    Optimising uniformity of InAs/(InGaAs)/GaAs quantum dots grown by metal organic vapor phase epitaxy2006Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, nr 15, s. 5525-5529Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A route towards optimisation of uniformity and density of InAs/(InGaAs)/GaAs quantum dots grown by metal organic vapor phase epitaxy (MOVPE) through successive variations of the growth parameters is reported. It is demonstrated that a key parameter in obtaining a high density of quantum dots is the V/III ratio, a fact which was shown to be valid when either AsH3 (arsine) or tertiary-butyl-arsine (TBA) were used as group V precursors. Once the optimum V/III ratio was found, the size distribution was further improved by adjusting the nominal thickness of deposited InAs material, resulting in an optimum thickness of 1.8 monolayers of InAs in our case. The number of coalesced dots was minimised by adjusting the growth interruption time to approximately 30 s. Further, the uniformity was improved by increasing the growth temperature from 485 °C to 520 °C. By combining these optimised parameters, i.e. a growth temperature of 520 °C, 1.8 monolayers InAs thickness, 30 s growth stop time and TBA as group V precursor, a full-width-half-maximum (FWHM) of the low temperature luminescence band of 40 meV was achieved, indicating a narrow dot size distribution.

    Fulltekst (pdf)
    FULLTEXT01
  • 40.
    Ivashchuk, Anatoliy V
    et al.
    Natl Tech Univ Ukraine, Ukraine.
    Dusheiko, Mykhailo G.
    Natl Tech Univ Ukraine, Ukraine.
    Roshchina, Nina M.
    NAS Ukraine, Ukraine.
    Smertenko, Petro S.
    NAS Ukraine, Ukraine.
    Dimitriev, Oleg
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten. NAS Ukraine, Ukraine.
    Liu, Xianjie
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Fahlman, Mats
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Impact of molecular layer on emergent photovoltaic response in silicon unraveled by photoelectron spectroscopy2021Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 544, artikkel-id 148807Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The large photovoltaic response from homogeneous silicon wafer obtained upon deposition of a molecular layer on its surface remained an unexplained phenomenon so far. Here, we show by X-ray and ultraviolet photo-electron spectroscopy that deposition of species containing acidic groups on the surface of n-type silicon with native silicon oxide overlayer always results in increased work function of the hybrid interface. This effect is shown to originate due to the surface band bending of the silicon crystal upward, which is accompanied by a negative surface dipole formed. This effect is assigned to protonation of the silicon oxide film by molecular acidic groups, which in turn facilitates accumulation of a mirror negative charge at the Si-SiO2 interface, thus increasing the depth of the depletion region and height of the Schottky barrier in the silicon semiconductor, respectively. Comparison of the work functions of the samples in the dark and under illumination confirms formation of a depletion region at the silicon surface upon molecular adsorption.

  • 41.
    Jamnig, Andreas
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten. Institut Pprime, Département Physique et Mécanique des Matériaux, Université de Poitiers, Poitiers Cedex, France.
    Pliatsikas, Nikolaos
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten.
    Abadias, Grégory
    Institut Pprime, Département Physique et Mécanique des Matériaux, Université de Poitiers, Poitiers Cedex, France.
    Sarakinos, Kostas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten.
    On the effect of copper as wetting agent during growth of thin silver films on silicon dioxide substrates2021Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 538, artikkel-id 148056Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study the effect of Cu incorporation on the morphological evolution and the optoelectronic properties of thin Ag films deposited by magnetron sputtering on weakly-interacting SiO2 substrates. In situ and real time spectroscopic ellipsometry data show that by adding up to 4at.% Cu throughout the entire film deposition process, wetting of the substrate by the metal layer is promoted, as evidenced by a decrease of the thickness at which the film becomes continuous from 19.5nm (pure Ag) to 15nm (Ag96Cu4). The in situ data are consistent with ex situ x-ray reflectometry analyses which show that Cu-containing films exhibit a root mean square roughness of 1.3nm compared to the value 1.8nm for pure Ag films, i.e., Cu leads to smoother film surfaces. These morphological changes are coupled with an increase in continuous-layer electrical resistivity from 1.0×10-5Ωcm (Ag) to 1.25×10-5Ωcm (Ag96Cu4). Scanning electron microscopic studies of discontinuous layers reveal that the presence of Cu at the film growth front promotes smooth surfaces (as compared to pure Ag films) by hindering the rate of island coalescence. To further understand the effect of Cu on film growth and electrical properties, in a second set of experiments, we deploy Cu with high temporal precision to target specific film-formation stages. The results show that longer presence of Cu in the vapor flux and the film growth front promote flat morphology. However, both a flat surface and a continuous-layer electrical resistivity that is equal to that of pure Ag films can only be achieved when Cu is deployed during the first 2.4nm of film deposition, during which morphological evolution is, primarily, governed by island coalescence. Our overall results highlight potential pathways for fabricating high-quality multifunctional metal contacts in a wide range of optoelectronic devices based on weakly-interacting oxides and van der Waals materials.

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    fulltext
  • 42. Johansson, M.
    et al.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Hydrogen adsorbed on palladium during water formation studied with palladium membranes2001Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 173, nr 1-2, s. 122-133Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The amount of hydrogen adsorbed on palladium during water formation has been studied by measurements of the rate at which hydrogen permeates a palladium membrane. The water formation and hydrogen permeation rates were measured simultaneously for palladium membranes exposed to a hydrogen-oxygen-argon mixture on one side and to pure argon on the other side. Investigations were carried out for the temperatures 100, 150 and 200 °C at a total pressure of 760 Torr. If the rates are plotted as a function of a, where a = pH(2)/(pH(2)+pO(2)), pH(2) and pO(2) are the pressures of hydrogen and oxygen at the palladium surface, respectively, it is found that, at 100 °C, a peak occurs in the water formation rate at amax˜0.2. The palladium surface is dominated by hydrogen for a>amax and is hydrogen deficient for a>amax. This is consistent with a rate limiting step for the water forming reaction where adsorbed hydrogen is one of the reactants. It is also concluded that the heat of adsorption for hydrogen on the palladium surface is significantly lower than previously derived from experiments made under ultrahigh vacuum conditions.

  • 43. Johansson, M.
    et al.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    The water formation rate on platinum and palladium as a function of the surface hydrogen pressure from three-dimensional hydrogen pressure distributions2001Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 180, nr 1-2, s. 27-35Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The water formation rate on platinum and palladium as a function of the reactant pressures at the catalytic surface has been determined from measurements of the three-dimensional hydrogen pressure distributions over the catalytic surface. Measurements were made for gas mixtures containing less than 1% of hydrogen and 20% of oxygen in argon at atmospheric pressure. The experiments were performed in a reactor with a simple and well-defined geometry which makes it possible to calculate the hydrogen pressure distribution in the entire region where measurements are made. The water formation rate as a function of the hydrogen pressure at the catalytic surface is obtained by comparing calculated hydrogen pressure distributions to measured ones. It is concluded that three-dimensional reactant pressure distributions can be used to accurately determine the reaction rate on a catalytic surface as a function of the reactant pressures at the surface. This is valuable for studies in the viscous pressure regime, where mass transfer limitations may be difficult to avoid. © 2001 Elsevier Science B.V.

  • 44.
    Jokubavicius, Valdas
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Yazdi, Gholamreza
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ivanov, Ivan G.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Niu, Yuran
    Max Lab, Lund University.
    Zakharov, Alexei
    Max Lab, Lund University.
    Lakimov, Tihomir
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Syväjärvi, Mikael
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Surface engineering of SiC via sublimation etching2016Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 390, s. 816-822Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a technique for etching of SiC which is based on sublimation and can be used to modify the morphology and reconstruction of silicon carbide surface for subsequent epitaxial growth of various materials, for example graphene. The sublimation etching of 6H-, 4H- and 3C-SiC was explored in vacuum (10−5 mbar) and Ar (700 mbar) ambient using two different etching arrangements which can be considered as Si-C and Si-C-Ta chemical systems exhibiting different vapor phase stoichiometry at a given temperature. The surfaces of different polytypes etched under similar conditions are compared and the etching mechanism is discussed with an emphasis on the role of tantalum as a carbon getter. To demonstrate applicability of such etching process graphene nanoribbons were grown on a 4H-SiC surface that was pre-patterned using the thermal etching technique presented in this study.

  • 45.
    Kakanakova-Georgieva, Anelia
    et al.
    Bulgarian Academy of Sciences, Sofia.
    Kassamakova, L
    Bulgarian Academy of Sciences, Plovdiv, Bulgaria.
    Marinova, Ts.
    Bulgarian Academy of Sciences, Sofia.
    Kakanakov, R.
    Bulgarian Academy of Sciences, Plovdiv, Bulgaria.
    Noblanc, O.
    Thomson-CSF/LCR, Orsay Cedex, France.
    Arnodo, C.
    Thomson-CSF/LCR, Orsay Cedex, France.
    Cassette, S.
    Thomson-CSF/LCR, Orsay Cedex, France.
    Brylinski, C.
    Thomson-CSF/LCR, Orsay Cedex, France.
    Interface chemistry of WN/4H-SiC structures1999Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 151, nr 3-4, s. 225-232Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interface chemistry of WN/4H–SiC structures has been studied by means of X-ray photoelectron spectroscopy (XPS). XPS investigations have been performed on as deposited, 800°C and 1200°C annealed (4 min) samples. The as deposited and 800°C annealed samples are characterized by chemically inert interfaces. Complete nitrogen out-diffusion from the WN layer, significant carbon diffusion into the contact layer, tungsten carbide and tungsten silicide formation occur during the 1200°C annealing process. The 800°C annealed WN/4H–SiC contacts are found to be of a Schottky type with a barrier height of 0.91 eV. The Schottky barrier height and the ideality factor show no significant changes during 100 h storage at 500°C under nitrogen and during operation at increasing temperature up to 350°C in air.

  • 46.
    Kakanakova-Georgieva, Anelia
    et al.
    Bulgarian Academy of Sciences, Sofia .
    Marinova, Ts.
    Bulgarian Academy of Sciences, Sofia .
    Noblanc, O.
    Thomson-CSF/LCR, Orsay Cedex, France.
    Arondo, C.
    Thomson-CSF/LCR, Orsay Cedex, France.
    Cassette, S.
    Thomson-CSF/LCR, Orsay Cedex, France.
    Brylinski, C.
    Thomson-CSF/LCR, Orsay Cedex, France.
    Interface chemistry of a Ti/ Au/ Pt/ Ti/ SiC structure1997Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 121/122, s. 208-212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) is used to investigate the chemical reactions and diffusion processes at Ti/Au/Pt/Ti/SiC interfaces for as deposited and annealed at 575°C for 10 min structures. The distribution of the elements and the change in their chemical state has been studied. The XP spectra indicate titanium carbide and platinum silicides formation at the SiC interface, which is preceded by the dissociation of SiC due to the reactivity of Ti at 575°C. TiC represents a barrier to the further diffusion of Ti to the SiC bulk and the Ti layer makes the diffusion of Pt into SiC difficult. The element distribution of the annealed structure demonstrates that Pt has diffused through almost the whole gold layer to the surface, an alloy of the two metals being formed.

  • 47.
    Kakanakova-Gueorguieva, Anelia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Giannazzo, Filippo
    CNR, Italy.
    Nicotra, Giuseppe
    CNR, Italy.
    Cora, Ildiko
    Inst Tech Phys & Mat Sci, Hungary.
    Gueorguiev, Gueorgui Kostov
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Pecz, Bela
    Inst Tech Phys & Mat Sci, Hungary.
    Material proposal for 2D indium oxide2021Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 548, artikkel-id 149275Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Realization of semiconductor materials at the two-dimensional (2D) limit can elicit exceptional and diversified performance exercising transformative influence on modern technology. We report experimental evidence for the formation of conceptually new 2D indium oxide (InO) and its material characteristics. The formation of 2D InO was harvested through targeted intercalation of indium (In) atoms and deposition kinetics at graphene/SiC interface using a robust metal organic chemical vapor deposition (MOCVD) process. A distinct structural configuration of two sub-layers of In atoms in "atop" positions was imaged by scanning transmission electron microscopy (STEM). The bonding of oxygen atoms to indium atoms was indicated using electron energy loss spectroscopy (EELS). A wide bandgap energy measuring a value of 4.1 eV was estimated by conductive atomic force microscopy measurements (C-AFM) for the 2D InO.

    Fulltekst (pdf)
    fulltext
  • 48.
    Kaushik, Priya Darshni
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Jamia Millia Islamia, India.
    Ivanov, Ivan Gueorguiev
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Lin, Pin-Cheng
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Kaur, Gurpreet
    University of Delhi, India.
    Eriksson, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad sensorvetenskap. Linköpings universitet, Tekniska fakulteten.
    Lakshmi, G. B. V. S.
    Interuniv Accelerator Centre, India.
    Avasthi, D. K.
    Interuniv Accelerator Centre, India; Amity Institute Nanotechnol, India.
    Gupta, Vinay
    University of Delhi, India.
    Aziz, Anver
    Jamia Millia Islamia, India.
    Siddiqui, Azher M.
    Jamia Millia Islamia, India.
    Syväjärvi, Mikael
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Yazdi, Gholamreza
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Surface functionalization of epitaxial graphene on SiC by ion irradiation for gas sensing application2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 403, s. 707-716Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, surface functionalization of epitaxial graphene grown on silicon carbide was performed by ion irradiation to investigate their gas sensing capabilities. Swift heavy ion irradiation using 100 MeV silver ions at four varying fluences was implemented on epitaxial graphene to investigate morphological and structural changes and their effects on the gas sensing capabilities of graphene. Sensing devices are expected as one of the first electronic applications using graphene and most of them use functionalized surfaces to tailor a certain function. In our case, we have studied irradiation as a tool to achieve functionalization. Morphological and structural changes on epitaxial graphene layers were investigated by atomic force microscopy, Raman spectroscopy, Raman mapping and reflectance mapping. The surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles at highest fluence (2 x 10(13) ions/cm(2)). Raman spectra analysis shows that the graphene defect density is increased with increasing fluence, while Raman mapping and reflectance mapping show that there is also a reduction of monolayer graphene coverage. The samples were investigated for ammonia and nitrogen dioxide gas sensing applications. Sensors fabricated on pristine and irradiated samples showed highest gas sensing response at an optimal fluence. Our work provides new pathways for introducing defects in controlled manner in epitaxial graphene, which can be used not only for gas sensing application but also for other applications, such as electrochemical, biosensing, magnetosensing and spintronic applications. (C) 2017 Elsevier B.V. All rights reserved.

    Fulltekst (pdf)
    fulltext
  • 49.
    Keraudy, Julien
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Shimizu, Tetsuhide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten. Tokyo Metropolitan Univ, Japan.
    Helmersson, Ulf
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Jouan, P-Y
    Univ Nantes, France.
    Phase separation within NiSiN coatings during reactive HiPIMS discharges: A new pathway to grow NixSi nanocrystals composites at low temperature2018Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 454, s. 148-156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The precise control of the growth nanostructured thin films at low temperature is critical for the continued development of microelectronic enabled devices. In this study, nanocomposite Ni-Si-N thin films were deposited at low temperature by reactive high-power impulse magnetron sputtering. A composite Ni-Si target (15 at.% Si) in combination with a Ar/N-2 plasma were used to deposit films onto Si(0 01) substrates, without any additional substrate heating or any post-annealing. The films microstructure changes from a polycrystalline to nanocomposite structure when the nitrogen content exceeds 16 at.%. X-ray diffraction and (scanning) transmission electron microscopy analyses reveal that the microstructure consists of nanocrystals, NixSi (x amp;gt; 1) 7-8 nm in size, embedded in an amorphous SiN x matrix. It is proposed that this nanostructure is formed at low temperatures due to the repeated-nucleation of NixSi nanocrystals, the growth of which is restricted by the formation of the SiNx phase. X-ray photoelectron spectroscopy revealed the trace presence of a ternary solid solution mainly induced by the diffusion of Ni into the SiNx matrix. Four-probe electrical measurements reveal all the deposited films are electrically conducing.

  • 50.
    Keraudy, Julien
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten. IRT, France; University of Nantes, France.
    Ferrec, Axel
    University of Nantes, France.
    Richard-Plouet, Mireille
    University of Nantes, France.
    Hamon, Jonathan
    University of Nantes, France.
    Goullet, Antoine
    University of Nantes, France.
    Jouan, Pierre-Yves
    University of Nantes, France.
    Nitrogen doping on NiO by reactive magnetron sputtering: A new pathway to dynamically tune the optical and electrical properties2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 409, s. 77-84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    N-doped nickel oxide (NiO:N) thin films were deposited on glass and silicon substrates by reactive DC magnetron sputtering in Ar/O-2/N-2 gas atmosphere with a series of N-2/O-2 gas ratio ranging from 0 to 80%. X-ray diffraction measurements have revealed that the films are constituted of Ni1_xO grains and showed enhanced polycrystalline features with increasing N-doping concentration. For the first time, we report here that N-doping in the Ni-deficient NiO (Ni1-xO) film leads to a band-gap narrowing from 3.6 to 2.3 eV. X-ray photoelectron spectroscopy (XPS) measurements proved that up to 4 atomic percent (at.%) nitrogen can be incorporated at least at the surface of the NiO:N samples. In addition, XPS valence band spectra and UV-vis transmission measurements have demonstrated that the band-gap narrowing may originates from the contribution of an intermediate band (IB) similar to 2.4 eV just above the valence band maximum and the up-shifting of the valence band edge (similar to 0.3 eV) due to the introduction of occupied N 2p states. Local I-V measurements, carried out by conductive AFM (C-AFM), have revealed that the extrinsic doping of N atoms within the oxide can be a good way to precisely control the electrical conductivity of such p-type materials. (C) 2017 Elsevier B.V. All rights reserved.

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