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  • 51.
    Khranovskyy, Volodymyr
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Ekblad, Tobias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Surface morphology effects on the light-controlled wettability of ZnO nanostructures2012Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, nr 20, s. 8146-8152Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    ZnO nanostructures of diverse morphology with shapes of corrals and cabbages as well as open and filled hexagons and sheaves prepared by APMOCVD technique, are investigated with water contact angle (CA) analysis. The as-grown ZnO nanostructures exhibit pure hydrophobic behavior, which is enhanced with the increase of the nanostructures surface area. The most hydrophobic structures (CA = 124 degrees) were found to be the complex nanosheaf, containing both the macro-and nanoscale features. It is concluded that the nanoscale roughness contributes significantly to the hydrophobicity increase. The character of wettability was possible to switch from hydrophobic-to-superhydrophilic state upon ultra violet irradiation. Both the rate and amplitude of the contact angle depend on the characteristic size of nanostructure. The observed effect is explained due to the semiconductor properties of zinc oxide enhanced by increased surface chemistry effect in nanostructures.

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  • 52.
    Khun, Kimleang
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Hussain Ibupoto, Zafar
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Chey, Chan Oeurn
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Comparative study of ZnO nanorods and thin films for chemical and biosensing applications and the development of ZnO nanorods based potentiometric strontium ion sensor2013Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 268, s. 37-43Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the comparative study of ZnO nanorods and ZnO thin films were performed regarding the chemical and biosensing properties and also ZnO nanorods based strontium ion sensor is proposed. ZnO nanorods were grown on gold coated glass substrates by the hydrothermal growth method and the ZnO thin films were deposited by electro deposition technique. ZnO nanorods and thin films were characterised by field emission electron microscopy [FESEM] and X-ray diffraction [XRD] techniques and this study has shown that the grown nanostructures are highly dense, uniform and exhibited good crystal quality. Moreover, transmission electron microscopy [TEM] was used to investigate the quality of ZnO thin film and we observed that ZnO thin film was comprised of nano clusters. ZnO nanorods and thin films were functionalised with selective strontium ionophore salicylaldehyde thiosemicarbazone [ST] membrane, galactose oxidase, and lactate oxidase for the detection of strontium ion, galactose and l-lactic acid, respectively. The electrochemical response of both ZnO nanorods and thin films sensor devices was measured by using the potentiometric method. The strontium ion sensor has exhibited good characteristics with a sensitivity of 28.65 +/- 0.52 mV/decade, for a wide range of concentrations from 1.00 x 10(-6) to 5.00 x 10(-2) M, selectivity, reproducibility, stability and fast response time of 10.00 s. The proposed strontium ion sensor was used as indicator electrode in the potentiometric titration of strontium ion versus ethylenediamine tetra acetic acid [EDTA]. This comparative study has shown that ZnO nanorods possessed better performance with high sensitivity and low limit of detection due to high surface area to volume ratio as compared to the flat surface of ZnO thin films.

  • 53.
    Lauridsen, Jonas
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Nedfors, N
    Uppsala University, Sweden .
    Jansson, U
    Uppsala University, Sweden .
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ti-B-C nanocomposite coatings deposited by magnetron sputtering2012Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, nr 24, s. 9907-9912Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

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  • 54.
    Lee, Taewoong
    et al.
    Pusan Natl Univ, South Korea.
    Chae, Seongwook
    Pusan Natl Univ, South Korea.
    Heo, Woo Sub
    Pusan Natl Univ, South Korea.
    Kang, Haisu
    Univ Illinois, IL 61801 USA.
    Park, Jae Bin
    Pusan Natl Univ, South Korea.
    Park, Yiseul
    Pukyong Natl Univ, South Korea.
    Park, Tae Hyun
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Lee, Jin Hong
    Pusan Natl Univ, South Korea.
    Lee, Seung Geol
    Pusan Natl Univ, South Korea.
    Dye-functionalized carbonaceous interlayer as an efficient lithium polysulfide mediator for high performance lithium-sulfur batteries2024Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 649, artikel-id 159156Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lithium - sulfur (Li-S) batteries with their high theoretical energy density and abundant resources have been considered as a promising candidate for next-generation energy storage systems. Nonetheless, undesirable diffusion of lithium polysulfides (LiPSs) toward the lithium metal anode in electrolytes during discharge/charge cycles of Li-S batteries, which is known as shuttle behavior of LiPSs, degrades the long-term stability of Li-S batteries and limits their practical applications. Herein, we present dye-functionalized carbonaceous interlayer, in which organic dye containing nitrogen and sulfur functional groups are incorporated into the carbon matrix of a graphitic layer via hydrothermal process. The introduction of such functional interlayer in Li-S batteries reveals that the carbon matrix with various heteroatom moieties can create physically/chemically favorable active sites for trapping LiPSs and enhance LiPSs conversion toward insoluble products of Li2S/Li2S2, resulting in excellent rate capability and long-term stability with high coulombic efficiency. This study emphasizes the potential of organic dyes functionalization and demonstrates enhanced LiPSs conversion and long-term stability of Li-S batteries.

  • 55.
    Levin, Martina
    et al.
    Naphtenics Research AB Nynäs Petroleum.
    Wiklund, Per
    Naphtenics Research AB Nynäs Petroleum.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Adsorption and film growth of N-methylamino substituted triazoles on copper surfaces in dydrocarbon media2007Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 254, s. 1528-1533Artikel i tidskrift (Refereegranskat)
  • 56.
    Li, Junyi
    et al.
    KTH Royal Inst Technol, Sweden.
    Liu, Xianjie
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Jonsson, Mats
    KTH Royal Inst Technol, Sweden.
    UO2 dissolution in aqueous halide solutions exposed to ionizing radiation2024Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 646, artikel-id 158955Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we have experimentally studied UO2 dissolution in pure water and in 1 M aqueous solutions of either Cl- or Br- exposed to gamma-radiation. It has previously been found that high ionic strength can facilitate adsorption of dissolved UO?+ on UO2 surfaces. The adsorption is also affected by the solution pH relative to the point of zero charge of UO2. In our experiments, Br3 -was observed in 1 M Br- solution exposed to gamma-radiation. Experiments confirmed that Br3 -can quantitively oxidize UO2. XPS and UPS were used to characterize potential surface modifications after exposure. The XPS results show that the UO2 surfaces after exposure to gamma-radiation in pure water and in 1 M aqueous solutions of either Cl- or Br- were significantly oxidized with U(V) as the dominating state. U 4f7/2 and O 1 s spectra of the UO2 surface after exposure to gamma-radiation in pure water demonstrates the formation of uranyl peroxide secondary phases. UPS results indicate that there is a large percentage of U(VI) on the ultra-thin outer layer of UO2 after exposure to gamma-radiation in 1 M aqueous solutions of Br- and Cl-, and 100 % of U(VI) in the pure water case.

  • 57.
    Li, Yaohui
    et al.
    Jinan Univ, Peoples R China.
    Wang, Yufei
    Jinan Univ, Peoples R China.
    Zuo, Qiong
    Jinan Univ, Peoples R China.
    Li, Bolun
    Jinan Univ, Peoples R China.
    Li, Yukun
    Jinan Univ, Peoples R China.
    Cai, Wanzhu
    Jinan Univ, Peoples R China.
    Qing, Jian
    Jinan Univ, Peoples R China.
    Li, Yuan
    South China Univ Technol, Peoples R China.
    Liu, Xianjie
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Shi, Jifu
    Jinan Univ, Peoples R China.
    Hou, Lintao
    Jinan Univ, Peoples R China.
    Improved efficiency of organic solar cell using MoS2 doped poly (3,4-ethylenedioxythiophene)(PEDOT) as hole transport layer2022Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 590, artikel-id 153042Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report an efficient hole transporting layer (HTL) for organic solar cell (OSC) based on solution-processed organic-inorganic hybrid composed of ultrasonic-exfoliated MoS2 nanosheets and dopamine-copolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) derivative (DA-P). The OSCs based on this new hybrid HTL show a marked performance improvement over those with single-component HTLs, and they retain up to 80% of their original power conversion efficiency after 35 days. Our investigations reveal that the boost in performance is due to a synergistic effect that improves both hole transport and extraction ability. This effect is mainly due to the doping of exfoliated-MoS2 nanosheets on DA-P. We employ a comprehensive range of spectroscopies to uncover that the dopant is derived from the oxidation products of MoS2 nanosheets during the ultrasonic exfoliation. Our work demonstrates an efficient hybrid HTL and offers new insights into the interaction of exfoliated-MoS2 nanosheets and the PEDOT derivatives.

  • 58.
    Liu, Qing
    et al.
    Yangzhou Univ, Peoples R China.
    Wang, Xiaoyang
    Yangzhou Univ, Peoples R China.
    Zhu, Xingwang
    Yangzhou Univ, Peoples R China.
    Ding, Penghui
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Zhong, Kang
    Jiangsu Univ, Peoples R China.
    Liu, Jinyuan
    Jiangsu Univ, Peoples R China.
    Hua, Yingjie
    Hainan Normal Univ, Peoples R China.
    Hu, Qingsong
    Yangzhou Univ, Peoples R China.
    Yi, Jianjian
    Yangzhou Univ, Peoples R China.
    Xu, Hui
    Jiangsu Univ, Peoples R China.
    Wang, Xiaozhi
    Yangzhou Univ, Peoples R China.
    Ding, Jianning
    Yangzhou Univ, Peoples R China.
    Unraveling the unique role of brown graphitic carbon nitride in robust CO2 photoreduction2023Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 615, artikel-id 156173Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photocatalytic CO2 reduction is one of the important means to alleviate the energy crisis. In this work, an oxygen linked and brown graphitic carbon nitride (GACN) was successfully prepared by thermal polymerization after oil bath method. GACN introduced oxygen atoms on surface of BulkCN. Various characterizations of the material show that the prepared GACN has a different structure and higher photoelectronic activity compared to BulkCN. GACN possessed strong photocatalytic CO2 reduction capacity, and the photocatalytic activity was significantly improved compared with BulkCN. In view of density functional theory calculations, it is proved that the oxygen atoms introduced by GACN increase CO2 photoreaction reactivity, enhance electronic activity and reduce the reaction energy barrier. This work can have a positive effect on the photocatalytic application of g-C3N4 with the existence of oxygen atoms.

  • 59.
    Magnuson, Martin
    et al.
    Uppsala University.
    Butorin, Sergei M.
    Uppsala University.
    Werme, Lars
    Uppsala University.
    Nordgren, Joseph
    Uppsala University.
    Ivanov, Kirill E.
    RRC Kurchatov Institute, Moscow.
    Guo, Jinghua
    Lawrence Berkeley National Laboratory, Berkeley, USA.
    Shuh, David K.
    Lawrence Berkeley National Laboratory, Berkeley, USA.
    Uranium oxides investigated by X-ray absorption and emission spectroscopies2006Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, nr 115, s. 5615-6518Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

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  • 60.
    Magnuson, Martin
    et al.
    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.
    Eriksson, Fredrik
    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.
    Högberg, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Electronic Structure of ß-Ta Films from X-ray Photoelectron Spectroscopy and First-principles Calculations2019Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 470, s. 607-612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electronic structure and chemical bonding of ß-Ta synthesized as a thin 001-oriented film (space group P 21m) is investigated by 4f core level and valence band X-ray photoelectron spectroscopy and compared to α-Ta bulk. For the b-phase, the 4f7/2 peak is located at 21.91 eV and with the 4f5/2 at 23.81 eV which is 0.16 eV higher compared to the corresponding 4f peaks of the a-Ta reference. We suggest that this chemical shift originates from higher resistivity and tensile strain in the ß-Ta film. Furthermore, the 5d-5s states at the bottom of the valence band are shifted by 0.75 eV towards higher binding energy in ß-Ta compared to α-Ta. This is a consequence of the lower number of nearest neighbors with four in ß-Ta compared to eight in the α-Ta phase. The difference in the electronic structures, spectral line shapes of the valence band and the energy positions of the Ta 4f, 5p core-levels of b-Ta versus a-Ta are discussed in relation to calculated states of ß-Ta and α-Ta. In particular, the lower number of states at the Fermi level of ß-Ta (0.557 states/eV/atom) versus α-Ta (1.032 states/eV/atom) that according to Mott’s law should decrease the conductivity in metals and affect the stability by charge redistribution in the valence band. This is experimentally supported from resistivity measurements of the film yielding a value of ~170 µW cm in comparison to α-Ta bulk with a reported value of ~13.1 µW cm.

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  • 61.
    Malysheva, Liubov
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Onipko, A
    Valiokas, Ramunas
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Liedberg, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik.
    First-principles modeling of oligo(ethylene glycol)-terminated and amide group containing alkanethiolates2005Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 246, nr 4, s. 372-376Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, self-assemblies of HS(CH2)(15)CONH(CH2CH2O)(6)H were found to undergo a reversible temperature-driven conformational transition from the helical to all-trans state [R. Valiokas, M. Ostblom, S. Svedhem, S.C.T. Svensson, B. Liedberg 104 (2000) 7565]. The transition reveals distinctive signatures in the reflection-absorption (RA) spectrum associated with different conformations of the OEG portion of the SAM [R. Valiokas, M. Ostblom, S. Svedhem, S.C.T. Svensson, B. Liedberg 104 (2000) 7565]. Here we report an extensive ab initio modeling of infrared RA spectra of molecular constituents of OEG-terminated amide-containing SAMs. The model spectra for this type of molecules (with large OEG and alkyl portions) are obtained, for the first time, by using DFT methods with gradient corrections. The position and relative intensities of all characteristic bands, observed in the fingerprint region of the SAM RA spectrum, are shown to be well reproduced by the single-molecule model spectrum calculated for a certain relative orientation of the alkyl- and OEG portions and the amide bridge. This provides us additional information about actual structure, particularly, molecular orientation within the OEG-containing SAMs in focus. (c) 2004 Elsevier B.V. All rights reserved.

  • 62.
    Marinova, Ts.
    et al.
    Bulgarian Academy of Sciences, Sofia.
    Kakanakova-Georgieva, Anelia
    Bulgarian Academy of Sciences, Sofia.
    Kalitzova, M.
    Bulgarian Academy of Sciences, Sofia.
    Vitali, G.
    Universita ‘‘La Sapienza'', Rome.
    Pizzuto, C.
    Universita ‘‘La Sapienza'', Rome.
    Zollo, G.
    Universita ‘‘La Sapienza'', Rome.
    XPS depth profiling of laser-annealed Zn+-implanted GaAs1997Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 109/110, s. 80-86Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Data on the effects of 140 keV Zn+-implantation in (100) GaAs and the consequent low power pulsed laser annealing (LPPLA) on the As/Ga ratio and the chemical states of the elements at the surface and in the subsurface region are presented. The results include the depth distribution of the elements for virgin, as-implanted and implanted+LPPLA [30×(4.5/7.5) MW/cm2] samples. The X-ray photoelectron spectra of as-implanted samples show that a low-intensity Zn 2p peak is observed after 20 min of Ar+ sputtering with an energy of 3 keV, corresponding to about 20 nm of etched material. The depth profiling XPS analysis confirms the ‘recovering' of the stoichiometry of Zn+-implanted specimens after LPPLA with laser pulses of a power density in the energy window of (5–7 MW/cm2). At laser pulse power densities outside of this energy window (4.5 and 7.5 MW/cm2) Zn appears again in the XP spectra after 20 min sputtering as in the case of as-implanted GaAs.

  • 63.
    Mock, Alyssa
    et al.
    University of Nebraska Lincoln, NE USA.
    Carlson, Timothy
    University of Nebraska Lincoln, NE USA.
    VanDerslice, Jeremy
    University of Nebraska Lincoln, NE USA; JA Woollam Co Inc, NE USA.
    Mohrmann, Joel
    JA Woollam Co Inc, NE USA.
    Woollam, John A.
    University of Nebraska Lincoln, NE 68588 USA; JA Woollam Co Inc, NE USA.
    Schubert, Eva
    University of Nebraska Lincoln, NE USA.
    Schubert, Mathias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. University of Nebraska Lincoln, NE USA; Leibniz Institute Polymer Research Dresden, Germany.
    Multiple-layered effective medium approximation approach to modeling environmental effects on alumina passivated highly porous silicon nanostructured thin films measured by in-situ Mueller matrix ellipsometry2017Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, s. 663-666Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Optical changes in alumina passivated highly porous silicon slanted columnar thin films during controlled exposure to toluene vapor are reported. Electron-beam evaporation glancing angle deposition and subsequent atomic layer deposition are utilized to deposit alumina passivated nanostructured porous silicon thin films. In-situ Mueller matrix generalized spectroscopic ellipsometry in an environmental cell is then used to determine changes in optical properties of the nanostructured thin films by inspection of individual Mueller matrix elements, each of which exhibit sensitivity to adsorption. The use of a multiple-layered effective medium approximation model allows for accurate description of the inhomogeneous nature of toluene adsorption onto alumina passivated highly porous silicon slanted columnar thin films. (C) 2016 Elsevier B.V. All rights reserved.

  • 64.
    Nilsson, H.-E.
    et al.
    Department of Information Technology, Mid-Sweden University, S-851 70 Sundsvall, Sweden.
    Martinez, A.
    Department of Electronics, Kungl. Tekniska Högskolan, Electrum 229, S-164 40 Kista, Sweden.
    Sannemo, Ulf
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Numerical study of Bloch electron dynamics in wide band-gap semiconductors2001Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 184, nr 1-4, s. 199-203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we are using numerical calculations to demonstrate the importance of band to band tunneling in wide band-gap semiconductors. We have considered 4H-SiC, 3C-SiC and wurtzite GaN as prototype semiconductors in the demonstration. Wide band-gap semiconductors allow device operation under very high-applied electric fields, where significant band to band tunneling is expected to occur. Hexagonal wide band-gap semiconductors have a valence band structure with a large number of bands separated by rather small energies. Our calculation shows that this leads to a very significant band to band tunneling even at relatively low electric fields. In cubic wide band-gap semiconductors the tunneling is much less pronounced. However, at the valence band maximum the band separations are small enough to allow significant band to band tunneling. The spin-orbit interaction tends to bend the band near the maximum creating degradation from a parabolic curvature. This bending is found to significantly influence the band to band tunneling process. © 2001 Elsevier Science B.V. All rights reserved.

  • 65.
    Nilsson, Sara
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Björefors, Fredrik
    Uppsala University, Sweden .
    Robinson, Nathaniel D.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Electrochemical quartz crystal microbalance study of polyelectrolyte film growth under anodic conditions2013Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 280, s. 783-790Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coating hard materials such as Pt with soft polymers like poly-l-lysine is a well-established technique for increasing electrode biocompatibility. We have combined quartz crystal microgravimetry with dissipation with electrochemistry (EQCM-D) to study the deposition of PLL onto Pt electrodes under anodic potentials. Our results confirm the change in film growth over time previously reported by others. However, the dissipation data suggest that, after the short initial phase of the process, the rigidity of the film increases with time, rather than decreasing, as previously proposed. In addition to these results, we discuss how gas evolution from water electrolysis and Pt etching in electrolytes containing Cl affect EQCM-D measurements, how to recognize these effects, and how to reduce them. Despite the challenges of using Pt as an anode in this system, we demonstrate that the various electrochemical processes can be understood and that PLL coatings can be successfully electrodeposited.

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  • 66.
    Näslund, Lars-Åke
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    XPS spectra curve fittings of Ti3C2Tx based on first principles thinking2022Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 593, artikel-id 153442Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    MXenes are an interesting family of 2D materials that have the potential to meet challenges in many applications. A useful tool in the work of understanding the nature of the MXenes, as well as exploring their capabilities, is Xray photoelectron spectroscopy (XPS). In analyzing XPS spectra it might be necessary to use curve fitting to extract valuable information. However, approaches toward the curve fitting procedure have been different in many studies and introductions of questionable assumptions, unverified feature assignments, and inconsistent curve fitting have led to contrasting conclusions from XPS analysis. It is therefore motivated to show curve fittings of F 1s, O 1s, Ti 2p, and C 1s XPS spectra obtained from high quality Ti3C2Tx that are based on fundamental knowledge applied step by step through the strategy of first principles thinking. With the use of first principles thinking the curve fittings and the subsequent analysis became more realistic compared to what have been presented in recent studies. The results of the curve fittings presented in this work are well founded and can be used as a model for future curve fittings of MXenes. The strategy of first principles thinking is advantageous in XPS curve fittings in general.

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  • 67. Petersson, L.-G.
    et al.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Fogelberg, J.
    Lundström, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Oxygen as a poison or promoter in the catalytic dissociation of H2, C2H2, C2H4, and NH3 on palladium1986Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 27, s. 275-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dissociation rates of H2, C2H4, C2H4, and NH3 have been studied on oxygen covered Pd surfaces by measuring the water desorption rates during exposure to each of the molecules. These results are correlated with the hydrogen response of a Pd-MOS structure. The measurements show a trend (at 473 K) where oxygen blocks H2 dissociation, blocks C2H4 dissociation only above a certain oxygen coverage, has no influence on C2H2 dissociation, and promotes NH3 dissociation.

  • 68.
    Pliatsikas, Nikolaos
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten.
    Karabinaki, O.
    Aristotle Univ Thessaloniki, Greece.
    Zarshenas, Mohammad
    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.
    Shtepliuk, Ivan
    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.
    Arvanitidis, J.
    Aristotle Univ Thessaloniki, Greece.
    Christofilos, D.
    Aristotle Univ Thessaloniki, Greece.
    Sarakinos, Kostas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten. Univ Helsinki, Finland.
    Energetic bombardment and defect generation during magnetron-sputter-deposition of metal layers on graphene2021Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 566, artikel-id 150661Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, we elucidate the interplay among energetic bombardment effects in magnetron sputtering and defect generation in two-dimensional (2D) materials. Using deposition of gold (Au) layers on single-layer graphene (SLG) as a model system, we study the effect of pressure-distance (pd) product during magnetron sputtering on the pristine SLG properties. Raman spectroscopy, complemented by X-ray photoelectron spectroscopy, shows that for pd = 8.2 Pa center dot cm, Au layer deposition causes defects in the SLG layer, which gradually diminish and eventually disappear with increasing pd to 82.5 Pa center dot cm. Stochastic and deterministic simulations of the sputtering process, the gas-phase transport, and the interaction of sputtered and plasma species with the substrate surface suggest that defects in SLG primarily emanate from ballistic damage caused by backscattered Ar atoms with energies above 100 eV. With increasing pd, and thereby gas-phase scattering, such high energy Ar species become thermalized and hence incapable of causing atomic displacements in the SLG layer. The overall results of our study suggest that control of backscattered Ar energy is a potential path toward enabling magnetron sputtering for fabrication of multifunctional metal contacts in devices founded upon 2D materials.

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  • 69.
    Qing, Jian
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Jinan Univ, Peoples R China; Shenzhen Univ, Peoples R China.
    Ramesh, Sankaran
    Nanyang Technol Univ, Singapore; Nanyang Technol Univ, Singapore.
    Liu, Xiaoke
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Wang, Heyong
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Yu, Hongling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Kuang, Chaoyang
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Hou, Lintao
    Jinan Univ, Peoples R China.
    Zhang, Wenjing
    Shenzhen Univ, Peoples R China.
    Sum, Tze Chien
    Nanyang Technol Univ, Singapore.
    Gao, Feng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Spacer cation engineering in Ruddlesden-Popper perovskites for efficient red light-emitting diodes with recommendation 2020 color coordinates2023Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 616, artikel-id 156454Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ruddlesden-Popper perovskites (RPPs) have been demonstrated as a very promising approach for tuning the emission color of perovskite light-emitting diodes (PeLEDs). However, achieving high-performance red PeLEDs with recommendation 2020 color coordinates is still challenging due to the lack of reasonable control over the properties of RPP films. Here, we demonstrate that the judicious selection of spacer cations in RPPs affords a lever for engineering their film properties, including phase distribution, energy funneling process, trap density, and carrier mobility. Four structurally related spacer cations, benzylammonium (BZA), phenylethylammonium (PEA), 3-phenyl-1-propylammonium (PPA), and phenoxyethylammonium (POEA), are studied. Owing to narrow phase distribution, efficient energy funneling, and low trap density, the POEA-based RPP films enable efficient red PeLEDs with a peak external quantum efficiency of 10.3%, a maximum brightness of 1052 cd m- 2, and excellent spectral stability. Significantly, the electroluminescence spectrum represents CIE 1931 color coordinates of (0.71, 0.29), which meets the recommendation 2020 standard (0.708, 0.292). The findings provide useful guidelines for the rational design of new organic spacer cations for RPPs with high performance.

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  • 70.
    Rice, Charles
    et al.
    University of Nebraska, NE USA.
    Mock, Alyssa
    University of Nebraska, NE USA.
    Sekora, Derek
    University of Nebraska, NE USA.
    Schmidt, Daniel
    University of Nebraska, NE USA.
    Hofmann, Tino
    University of Nebraska, NE USA.
    Schubert, Eva
    University of Nebraska, NE USA.
    Schubert, Mathias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. University of Nebraska, NE 68588 USA; University of Nebraska, NE USA; Leibniz Polymer Research Institute, Germany.
    Control of slanting angle, porosity, and anisotropic optical constants of slanted columnar thin films via in situ nucleation layer tailoring2017Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, s. 766-771Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electron-beam evaporation at a glancing angle of 85 is utilized to fabricate highly ordered, spatially coherent titanium slanted columnar thin films. Prior to deposition of the slanted columnar thin films, a titanium nucleation layer is deposited using electron-beam deposition at normal incidence with various intended nucleation layer thicknesses of 0 nm, 5 nm, 7.5 nm, 10 nm, 20 nm, and 50 nm. Structural and optical properties of the anisotropic porous thin films are studied by scanning electron microscopy, atomic force microscopy, and Mueller matrix generalized spectroscopic ellipsometry in the near infrared to ultra-violet spectral regions. An anisotropic effective medium approximation is employed for analysis of the ellipsometry data in order to determine slanting angle and porosity model parameters. We find that the slanting angle and titanium volume fraction are strongly influenced by the nucleation layer thickness. Structural parameters of SCTFs deposited on 50 nm nucleation layers are similar to those from SCTFs with no nucleation layer. For small nucleation layer thicknesses, the corresponding SCTF slanting angle and titanium volume fraction decrease reaching a minimum of approximate to 33 degrees and approximate to 12% respectively, at 10 nm nucleation layer thickness. In accordance with the strong decrease in volume fraction we observe substantial reduction of the effective anisotropic thin film optical constants. We find the slanting angle and porosity variation reproducible and suggest use of a nucleation layer for control of slanting angle and porosity of slanted columnar thin films. (C) 2017 Published by Elsevier B.V.

  • 71.
    Ritchie, Andrew
    et al.
    University of Saskatchewan, Saskatoon, SK, Canada.
    Eger, Shaylin
    University of Saskatchewan, Saskatoon, SK, Canada.
    Wright, Chelsey
    Canadian Light Source, Saskatoon, SK, Canada.
    Chelladurai, Saniel
    University of Saskatchewan, Saskatoon, SK, Canada.
    Borrowman, Cuyler
    University of Saskatchewan, Saskatoon, SK, Canada.
    Olovsson, Weine
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Magnuson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Verma, Jai
    University of Notre Dame, IN, USA.
    Jena, Debdeep
    Univeristy of Notre Dame, IN, USA.
    Grace Xing, Huili
    University of Notre Dame, IN, USA.
    Duboc, Christian
    Osemi Canada Inc., Sherbrooke, Quebec, Canada.
    Urquhart, Stephen
    University of Saskatchewan, Saskatoon, SK, Canada.
    Strain sensitivity in the nitrogen 1s NEXAFS spectra of gallium nitride2014Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 316, s. 232-236Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nitrogen 1s near edge X-ray absorption fine structure (NEXAFS) of gallium nitride (GaN) shows astrong natural linear dichroism that arises from its anisotropic wurtzite structure. An additional spectro-scopic variation arises from lattice strain in epitaxially grown GaN thin films. This variation is directlyproportional to the degree of strain for some spectroscopic features. This strain variation is interpretedwith the aid of density functional theory calculations.

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  • 72.
    Rittiruam, Meena
    et al.
    Chulalongkorn Univ, Thailand.
    Khamloet, Pisit
    Chulalongkorn Univ, Thailand.
    Ektarawong, Annop
    Chulalongkorn Univ, Thailand.
    Atthapak, Chayanon
    Chulalongkorn Univ, Thailand.
    Saelee, Tinnakorn
    Chulalongkorn Univ, Thailand.
    Khajondetchairit, Patcharaporn
    Chulalongkorn Univ, Thailand.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Praserthdam, Supareak
    Chulalongkorn Univ, Thailand; Chulalongkorn Univ, Thailand.
    Praserthdam, Piyasan
    Chulalongkorn Univ, Thailand.
    Screening of Cu-Mn-Ni-Zn high-entropy alloy catalysts for CO2 reduction reaction by machine-learning-accelerated density functional theory2024Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 652, artikel-id 159297Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-entropy-alloy (HEA) catalysts have been used in many challenging electrocatalytic reactions, e.g., CO2 reduction reaction (CO2RR) due to their promising properties. For CO2RR catalysts, tuning metal compositions in Cu-based catalysts is one of the techniques to control the desired products. Thus, this work investigated the optimal composition of Cu-Mn-Ni-Zn HEA catalysts using high-throughput screening (HTS) for CO2RR targeting on two competing routes toward CH4 and CH3OH products. The screening protocol evaluates catalytic activity through adsorption energy (Eads) of *CO2, *CO, *COOH, and *H. At the same time, the selectivity is represented by Eads of *COH, *CH4, *CHO, and *CH3OH, using density functional theory (DFT) accelerated by machine learning techniques. The screening result from 11,920 data revealed 259 candidates for CH4-selective and 4,214 for CH3OH-selective catalysts. Interestingly, the Cu-Mn-Ni-Zn excellently prevented competitive hydrogen evolution reaction by up to 90%. Optimal composition for each route are Cu0.1Mn0.4Ni0.2Zn0.3 and Cu0.2Mn0.4- Ni0.1Zn0.3 in CH4-selective route and Cu0.3Mn0.3Ni0.2Zn0.2, Cu0.3Mn0.2Ni0.3Zn0.2, Cu0.3Mn0.2Ni0.2Zn0.3, and Cu0.2Mn0.3Ni0.3Zn0.2 in CH3OH-selective route. The optimal catalyst structure with high CO2RR activity in both routes was revealed to have the Mn atom as an active site, while Cu, Ni, and Zn as neighboring atoms. Hence, the Cu-Mn-Ni-Zn HEA catalyst is the promising electrocatalyst for CO2RR.

  • 73.
    Roccaforte, F.
    et al.
    CNR IMM, Italy.
    Greco, G.
    CNR IMM, Italy.
    Fiorenza, P.
    CNR IMM, Italy.
    Di Franco, S.
    CNR IMM, Italy.
    Giannazzo, F.
    CNR IMM, Italy.
    La Via, F.
    CNR IMM, Italy.
    Zielinski, M.
    NOVASiC, France.
    Mank, H.
    NOVASiC, France.
    Jokubavicius, Valdas
    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.
    Towards vertical Schottky diodes on bulk cubic silicon carbide (3C-SiC)2022Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 606, artikel-id 154896Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we demonstrate the feasibility of fabricating vertical Schottky diodes on bulk cubic silicon carbide (3C-SiC) material obtained by combining sublimation epitaxy and chemical vapor deposition, starting from 4 degrees -off axis 4H-SiC. First, the good quality of the epilayers grown with this method was demonstrated by morphological and structural analyses. Then, fabricated vertical Pt/3C-SiC Schottky diodes exhibited an ideality factor of 1.21 and a barrier height of 0.6 eV, as determined by thermionic emission model. The temperature dependent forward current analysis indicated the formation of an inhomogeneous barrier, which has been related with the presence of conductive surface defects, detected by nanoscale local current measurements. On the other hand, the reverse leakage current could be described by thermionic field emission model, including image force lowering. These findings demonstrate the viability of the proposed approach for bulk 3C-SiC growth for device fabrication. The material quality and the feasibility of fabricating vertical diodes based on 3C-SiC with a low barrier pave the way for the application of this polytype for medium-voltage power devices.

    Publikationen är tillgänglig i fulltext från 2024-09-15 15:51
  • 74.
    Rogström, Lina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Moreno, Maiara
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Andersson, J. M.
    Seco Tools AB, Fagersta, Sweden.
    Johansson-Jöesaar, M. P.
    Seco Tools AB, Fagersta, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Klementiev, K.
    MAX IV Laboratory, Lund University, Lund, Sweden.
    Näslund, Lars-Åke
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Magnuson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Structural changes in Ti1-xAlxN coatings during turning: A XANES and EXAFS study of worn tools2023Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 612, artikel-id 155907Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Structural changes in Ti1-xAlxN coated tool inserts used for turning in 316L stainless steel were investigated by XANES, EXAFS, EDS, and STEM. For coarse-grained fcc-structured Ti1-xAlxN coatings, with 0 ≤ x ≤ 0.62, the XANES spectrum changes with Al-content. XANES Ti 1s line-scans across the rake face of the worn samples reveals that TiN-enriched domains have formed during turning in Ti0.47Al0.53N and Ti0.38Al0.62N samples as a result of spinodal decomposition. The XANES spectra reveal the locations on the tool in which the most TiN-rich domains have formed, indicating which part of the tool-chip contact area that experienced the highest temperature during turning. Changes in the pre-edge features in the XANES spectra reveal that structural changes occur also in the w-TiAlN phase in fine-grained Ti0.38Al0.62N during turning. EDS shows that Cr and Fe from the steel adhere to the tool rake face during machining. Cr 1s and Fe 1s XANES show that Cr is oxidized in the end of the contact length while the adhered Fe retains in the same fcc-structure as that of the 316L stainless steel.

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  • 75.
    Saelee, Tinnakorn
    et al.
    Chulalongkorn Univ, Thailand; Chulalongkorn Univ, Thailand; Rittiruam Res Grp, Thailand.
    Boonchuay, Suphawich
    Chulalongkorn Univ, Thailand; Chulalongkorn Univ, Thailand.
    Sriwattana, Attachai
    Chulalongkorn Univ, Thailand; Chulalongkorn Univ, Thailand.
    Rittiruam, Meena
    Chulalongkorn Univ, Thailand; Chulalongkorn Univ, Thailand; Rittiruam Res Grp, Thailand.
    Khajondetchairit, Patcharaporn
    Chulalongkorn Univ, Thailand; Chulalongkorn Univ, Thailand; Khajondetchairit Res Grp, Thailand.
    Praserthdam, Supareak
    Chulalongkorn Univ, Thailand; Chulalongkorn Univ, Thailand.
    Ektarawong, Annop
    Chulalongkorn Univ, Thailand; Chulalongkorn Univ, Thailand; Chulalongkorn Univ, Thailand.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Praserthdam, Piyasan
    Chulalongkorn Univ, Thailand.
    On the enhanced performance of Pt-based high-entropy alloys catalyst during water-gas shift reaction: A density functional theory study2023Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 623, artikel-id 157023Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electricity production from clean energy sources has gained attention during these decades. However, many power plants worldwide still use coal and natural gas as raw materials, which generates toxic gases, especially CO and CO2. To deal with this problem, transforming generated CO into another useful precursor before sup-plying it to the chemical process is a good idea. One of the most effective approaches is WGSR using a highly effective catalyst. In this work, we elucidate the insight information of PtPdRhFeCo HEA(1 1 1) surface improving the catalytic efficiency of Pt(1 1 1) surface. Interestingly, the homogenous form of electron distribution along Pt (1 1 1) surface is changed to heterogeneous forms creating unique electronic properties in which the electron donor and acceptor species exist simultaneously. The weakening interaction of CO corresponding to the strengthening interaction of CO2 on HEA(1 1 1) surface are advantages to preventing CO poison and trapping the CO2 after the WGSR. Moreover, the HEA(1 1 1) surface can thermodynamically promote the dissociation of H2O in pre-WGSR, creating active species of H*, O*, and OH* supplying to further the WGSR process. Nevertheless, consideration of PES along WGSR demonstrates that all possible pathways, including carboxyl, redox, and formate pathways along HEA(1 1 1) surface, are significantly improved by enhancing the thermodynamic driving force producing CO2.

  • 76.
    Sangiovanni, Davide Giuseppe
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Copper adatom, admolecule transport, and island nucleation on TiN(0 0 1) via ab initio molecular dynamics2018Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 50, s. 180-189Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Density-functional ab initio molecular dynamics (AIMD) simulations are carried out to determine Cu adatom and admolecule transport properties as a function of temperature, as well as atomistic processes leading to formation of Cu/TiN(0 0 1) islands at 350 K. At very low temperatures T ≤ 200 K, Cu adatoms (Cuad) migrate among favored fourfold-hollow surface sites by passing across atop-Ti metastable positions. For increasing temperatures, however, Cuad transport becomes progressively more isotropic, and switches continuously from normal- to super-diffusive with mean-square displacement dependencies on time that alternate between linear and exponential. Despite that, the Cuad diffusivity D can be expressed by a fairly Arrhenius-like behavior D(T) = 8.26(×2±1) × 10−4 cm2 s−1exp[(−0.04 ± 0.01 eV)/(kBT)] over the entire investigated temperature range (100 ≤ T ≤ 1000 K). AIMD simulations also reveal that the condensation of Cu adatoms into Cux>1 adspecies is kinetically hindered by long-range (>5.5 Å) adatom/adatom repulsion. During Cu island nucleation, all Cu atoms occupy atop-N positions indicating favored Cu(0 0 1)/TiN(0 0 1) epitaxial growth. Nevertheless, Cu agglomerates formed by five, or more, atoms tend to arrange in 3D structures, which maximize intracluster bonds while minimizing film/substrate interactions. Results here presented provide insights for understanding the properties of weakly-interacting metal/substrate interface systems in general.

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  • 77.
    Schmeisser, D.
    et al.
    Schmeißer, D., Angewandte Physik-Sensorik, BTU Cottbus, Erich-Weinert-Str. 1, 03046 Cottbus, Germany.
    Batchelor, D.R.
    Angewandte Physik-Sensorik, BTU Cottbus, Erich-Weinert-Str. 1, 03046 Cottbus, Germany.
    Mikalo, R.P.
    Angewandte Physik-Sensorik, BTU Cottbus, Erich-Weinert-Str. 1, 03046 Cottbus, Germany.
    Hoffmann, P.
    Angewandte Physik-Sensorik, BTU Cottbus, Erich-Weinert-Str. 1, 03046 Cottbus, Germany.
    Lloyd-Spets, Anita
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Oxide growth on SiC(0 0 0 1) surfaces2001Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 184, nr 1-4, s. 340-345Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The oxidation of 6H SiC(0 0 0 1) surfaces is studied by high resolution photoelectron spectroscopy. We compare the oxides formed by HF dip, by room temperature treatment in ozone, and by thermal oxidation in air at 1000 °C, respectively. We find a stable intermediate layer in all investigated systems which differs from the bulk oxide that is stable up to 1200 °C. Our data suggest that the growth of the SiO2 layer proceeds via that intermediate silicate layer. © 2001 Published by Elsevier Science B.V.

  • 78.
    Sekora, Derek
    et al.
    University of Nebraska Lincoln, NE USA.
    Briley, Chad
    University of Nebraska Lincoln, NE USA.
    Schubert, Mathias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. University of Nebraska Lincoln, NE USA; Leibniz Institute Polymer Research Dresden, Germany.
    Schubert, Eva
    University of Nebraska Lincoln, NE USA.
    Optical and structural properties of cobalt-permalloy slanted columnar heterostructure thin films2017Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, s. 783-787Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Optical and structural properties of sequential Co-column-NiFe-column slanted columnar heterostructure thin films with an A1203 passivation coating are reported. Electron-beam evaporated glancing angle deposition is utilized to deposit the sequential multiple-material slanted columnar heterostructure thin films. Mueller matrix generalized spectroscopic ellipsometry data is analyzed with a best-match model approach employing the anisotropic Bruggeman effective medium approximation formalism to determine bulk-like and anisotropic optical and structural properties of the individual Co and NiFe slanted columnar material sub-layers. Scanning electron microscopy is applied to image the Co-NiFe sequential growth properties and to verify the results of the ellipsometric analysis. Comparisons to single-material slanted columnar thin films and optically bulk solid thin films are presented and discussed. We find that the optical and structural properties of each material sub-layer of the sequential slanted columnar heterostructure film are distinct from each other and resemble those of their respective single-material counterparts. (C) 2016 Elsevier B.V. All rights reserved.

  • 79.
    Semchuk, O. Yu
    et al.
    Institute of Surface Chemistry NAS of Ukraine.
    Semioshko, V.N.
    Institute of Surface Chemistry NAS of Ukraine.
    Grechko, L.G.
    Institute of Surface Chemistry NAS of Ukraine.
    Willander, Magnus
    Goteborg University.
    Karlsteen, M.
    Goteborg University.
    Laser ablation lithography on thermoelectric semconductor2006Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, nr 13, s. 4759-4762Artikel i tidskrift (Refereegranskat)
    Abstract [en]

      In this paper, experimental results of the investigation of the periodic structure on thermoelectric semiconductor Cu2Se are presented. Periodic structures were formed on surfaces of semiconductors due to multi-beam interaction of Q-switched Nd:YAG laser, which was operated in the lowest order of Gaussian mode and pulse duration 7 ns. Surface temperature evolution and transient reflectivity are studied during laser treatment. Creation of Cu islands in the maximal intensity of interference pattern was found.

  • 80.
    Shtepliuk, Ivan
    et al.
    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.
    Interaction of H and Li with epitaxial graphene on SiC: A comparative analysis by first principles study2021Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 568, artikel-id 150988Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ever-growing energy consumption in the world fosters the development of innovative energy technologies for sustainable energy production and storage. In this view, monolayer epitaxial graphene grown on 4H-SiC (MLEG/SiC) may be considered as a potential component of energy-related systems. The current paper deals with modelling of adsorption, diffusion and intercalation of hydrogen and lithium using MLEG/SiC model encompassing 2 x 2 graphene on root 3 x root 3R30 degrees surface reconstructed nine-bilayer 4H-SiC. The obtained results demonstrate a strong and stable chemisorption of hydrogen on top site of epitaxial graphene with limited surface mobility, while lithiation process occurs via formation of LiC6 phase. The stages of hydrogen and lithium intercalation beneath graphene are studied in detail by performing potential energy scan. Energetic preferences for MLEG/SiC with intercalated hydrogen and lithium atoms versus MLEG/SiC with top-adsorbed H and Li are revealed. Li intercalant-induced complete decoupling of the buffer layer from the SiC substrate followed by the formation of bilayer graphene with inequivalent doping per layer is proposed as an explanation of experimentally observed Raman G peak splitting in electrochemically lithiated epitaxial graphene on 4H-SiC. This work provides deep insights into the nature of atomic-scale processes at epitaxial graphene, which is essential for improving performance of energy-related devices.

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  • 81.
    Shtepliuka, I.
    et al.
    National Academy of Sciences of Ukraine, Kiev.
    Khranovskyy, Volodymyr
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lashkarev, G.
    National Academy of Sciences of Ukraine, Kiev.
    Khomyak, V.
    Chernivtsi National University, Ukraine.
    Ievtushenko, A.
    National Academy of Sciences of Ukraine, Kiev.
    Tkach, V.
    National Academy of Sciences of Ukraine, Kiev.
    Lazorenko, V.
    National Academy of Sciences of Ukraine, Kiev.
    Timofeeva, I.
    National Academy of Sciences of Ukraine, Kiev.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Microstructure and luminescence dynamics of ZnCdO films with high Cd content deposited on different substrates by DC magnetron sputtering method2013Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 276, s. 550-557Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Investigation of Cd behavior in the ZnCdO alloys, where Cd content exceeds the solubility limit, is of importance due to possible impurity segregation and second phases' formation in this material. We have studied the Cd behavior in the Zn1-xCdxO films deposited by dc magnetron sputtering on different substrates: c-plane Al2O3, bare Si (1 0 0) and Au (45 nm)/Si (1 0 0). It is revealed that Cd content of 10 at. % in the target results in average 6-8 at. % of Cd in the films, depending on the substrate type. Structural analysis based on X-ray diffraction revealed the absence of Cd-related secondary phases. Time-resolved photoluminescence (TRPL) and high-resolution energy dispersive X-ray analysis (EDX) help to understand the recombination dynamics of spontaneous emission and to establish correlations between cadmium content and radiative lifetime. We have revealed that the internal quantum efficiency is influenced by the Cd content and defect concentration. It is suggested that increasing of the cadmium content results in the reduction of nonradiative recombination centers originating from point defects.

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  • 82.
    Toropov, A.A.
    et al.
    Ioffe Institute of RAS, Politeknicheskaia 26, 194021, St. Petersburg, Russian Federation.
    Shubina, T.V.
    Ioffe Institute of RAS, Politeknicheskaia 26, 194021, St. Petersburg, Russian Federation.
    Sorokin, S.V.
    Ioffe Institute of RAS, Politeknicheskaia 26, 194021, St. Petersburg, Russian Federation.
    Kyutt, R.N.
    Ioffe Institute of RAS, Politeknicheskaia 26, 194021, St. Petersburg, Russian Federation.
    Ivanov, S.V.
    Ioffe Institute of RAS, Politeknicheskaia 26, 194021, St. Petersburg, Russian Federation.
    Pozina, Galia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Bergman, Peder
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Karlsteen, M.
    Chalmers Univ. Technol./Goteborg U., S-412 96, Göteborg, Sweden.
    Willander, M.
    Chalmers Univ. Technol./Goteborg U., S-412 96, Göteborg, Sweden.
    Excitons as a probe of interface morphology in Cd(Zn)Se/ZnSe heterostructures2000Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 166, nr 1, s. 278-283Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present studies of the excitonic spectrum in superlattices (SLs) of CdSe insertions in a ZnSe matrix aimed at elucidating the CdSe/ZnSe interface morphology. The experimental photoluminescence excitation spectra are compared with the results of variational exciton calculations performed within the effective mass approximation. The shape of the average vertical (along the SL growth axis) distribution of CdSe within each insertion, used in the calculations, was obtained from a theoretical simulation of X-ray diffraction (XRD) rocking curves measured in the same samples. The results indicate that the thinnest layers are graded composition ZnCdSe quantum wells (QWs), generally homogeneous in the layer planes, whereas flat islands enriched by Cd appear at the CdSe nominal thickness larger than 0.5-0.6 monolayer (ML).

  • 83.
    Torrisi, Lorenzo
    et al.
    University of Messina, Italy.
    Cutroneo, Maria
    INFN - Laboratori Nazionali del Sud, Catania, Italy.
    Cavallaro, Salvatore
    INFN - Laboratori Nazionali del Sud, Catania, Italy.
    Giuffirda, Lorenzo
    INFN - Laboratori Nazionali del Sud, Catania, Italy.
    Andò, L.
    INFN - Laboratori Nazionali del Sud, Catania, Italy.
    Cirrone, Pablo
    INFN - Laboratori Nazionali del Sud, Catania, Italy.
    Bertuccio, Giuseppe
    Politecnico di Milano, Como Campus, Italy.
    Puglisi, Donatella
    Politecnico di Milano, Como Campus, Italy.
    Calcagno, Lucia
    University of Catania, Italy.
    Verona, Claudio
    University of Rome "Tor Vergata", Italy.
    Picciotto, A.
    Fondazione Bruno Kessler–IRST, Povo, Trento, Italy.
    Krasa, J.
    Institute of Physics, ASCR, Prague, Czech Republic.
    Margarone, Daniele
    Institute of Physics, ASCR, Prague, Czech Republic.
    Velyhan, A.
    Institute of Physics, ASCR, Prague, Czech Republic.
    Laska, L.
    Institute of Physics, ASCR, Prague, Czech Republic.
    Krousky, E.
    Institute of Physics, ASCR, Prague, Czech Republic.
    Pfeiffer, M.
    Institute of Physics, ASCR, Prague, Czech Republic.
    Skala, J.
    Institute of Physics, ASCR, Prague, Czech Republic.
    Ullschmied, J.
    Institute of Physics, ASCR, Prague, Czech Republic.
    Wolowski, J.
    Institute of Plasma Physics and Laser Microfusion, IPPLM, Waesaw, Poland.
    Badziak, J.
    Institute of Plasma Physics and Laser Microfusion, IPPLM, Waesaw, Poland.
    Rosinski, M.
    Institute of Plasma Physics and Laser Microfusion, IPPLM, Waesaw, Poland.
    Ryc, L.
    Institute of Plasma Physics and Laser Microfusion, IPPLM, Waesaw, Poland.
    Szydlowski, A.
    Institute of Plasma Physics and Laser Microfusion, IPPLM, Waesaw, Poland.
    Proton driven acceleration by intense laser pulses irradiating thin hydrogenated targets2013Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 272, s. 2-5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Asterix iodine laser of the PALS laboratory in Prague, operating at 1315 nm fundamental frequency, 300 ps pulse duration, 600 J maximum pulse energy and 1016 W/cm2 intensity, is employed to irradiatethin hydrogenated targets placed in high vacuum. Different metallic and polymeric targets allow togenerate multi-energetic and multi-specie ion beams showing peculiar properties. The plasma obtainedby the laser irradiation is monitored, in terms of properties of the emitted charge particles, by using time-of-flight techniques and Thomson parabola spectrometer (TPS). A particular attention is given tothe proton beam production in terms of the maximum energy, emission yield and angular distributionas a function of the laser energy, focal position (FP), target thickness and composition.

  • 84.
    Trivedi, Maitrayee
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Pandit Deendayal Petr Univ, India.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Kanth P., Chandra
    Pandit Deendayal Petr Univ, India.
    Pandey, Manoj Kumar
    Pandit Deendayal Petr Univ, India.
    Ivanov, Ivan Gueorguiev
    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.
    Yazdi, Gholamreza
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Study of Cucurbit[7]uril nanocoating on epitaxial graphene to design a versatile sensing platform2021Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 563, artikel-id 150096Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Present study aimed to develop nanocoating of cucurbit[7]uril (CB[7]) on surfaces of silicon and epitaxial graphene using drop casting and spin coating techniques. Here, we report a systematic study for the influence of sonication, probe sonication, and centrifugation time on the dispersion of CB[7] in aqueous solutions for the preparation of high-quality CB[7] nanocoating. Spin speed, spin time, and spin acceleration have been optimised to attain uniform films with minimum rms. Atomic force microscopy is used to study morphology, rms, and height of CB[7] nanocoating under different parameters. The presence of CB[7] on the nanocoating and its binding nature was determined by Infrared absorption and X-ray photoelectron spectroscopy. The present method of CB[7] nanocoating preparation is easy, versatile, scalable, and does not need the addition of electrolyte additives. Prepared CB[7] films are high-quality, uniform, and could be used as a novel sensing platform to tether required functional groups.

  • 85.
    Virojanadara, Chariya
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Glans, P.-A.
    Johansson, Leif
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Eickhoff, Th.
    II. Inst. Exp. Phys., Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.
    Drube, W.
    Hamburger S., Deutschen Elektronen-Synchrt. DESY, D-22603 Hamburg, Germany.
    High energy photoemission investigations of SiO2/SiC samples2001Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 172, nr 3-4, s. 253-259Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chemically etched and directly load-locked SiO2/SiC samples are investigated using a photon energy of 3.0 keV. Si 2p and C 1s spectra recorded at different electron emission angles each show two components originating from SiC, SiO2 and graphite like carbon, respectively. The relative intensity of these are extracted and compared to calculated intensity variations. For the samples investigated, best agreement between experimental and calculated intensity variations is obtained when assuming a graphite like layer on top of the oxide. No graphite like carbon at the SiO2/SiC interface was detected, even on a sample for which the graphite like carbon contribution at the surface corresponds to a layer thickness of only 0.05 angstrom. The energy separation between the oxide and carbide components in the Si 2p spectrum was monitored before and after Ar+ sputtering cycles and before and after in situ heating. The separation increased directly upon sputtering while only in situ heating does not affect it. We suggest that defects induced by the sputtering give rise to the increase, observed in the energy separation.

  • 86.
    Wallin, M.
    et al.
    Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96, Göteborg, Sweden, Dept. of Applied Surface Chemistry, Chalmers University of Technology, SE-412 96, Göteborg, Sweden.
    Gronbeck, H.
    Grönbeck, H., Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96, Göteborg, Sweden, Department of Applied Physics, Chalmers University of Technology, SE-412 96, Göteborg, Sweden.
    Lloyd-Spets, Anita
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Skoglundh, M.
    Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96, Göteborg, Sweden, Dept. of Applied Surface Chemistry, Chalmers University of Technology, SE-412 96, Göteborg, Sweden.
    Vibrational study of ammonia adsorption on Pt/SiO22004Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 235, nr 4, s. 487-500Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Vibrational properties of surface species formed upon NH3 adsorption on Pt/SiO2, model system for the gas sensitive part in ammonia sensors based on field effect devices, have been investigated with in situ DRIFT spectroscopy. Experiments have been performed for a series of samples with different Pt loading at three temperatures, 50, 150 and 300°C, and in the absence and presence of oxygen. In addition, electronic structure calculations and vibrational analysis have been performed within the density functional theory (DFT) for NH3 and NH2 species adsorbed on platinum and hydroxylated silica model systems. Observations from both DRIFT spectra and DFT calculations indicate that NH3 is more strongly bound to platinum than to silanol groups on the SiO2 support. Vibrational modes assigned to NH2 appeared in the DRIFT experiments, indicative of NH3 dissociation, an interpretation supported by the calculations. Exposure of O2 was found to have minor effect on the vibrational spectrum at 50°C. However, at 150°C an increase of the vibration band assigned to the NH2 surface species was observed together with formation of gas phase N2O for samples with high platinum content. Thus, ammonia is oxidised over Pt at this temperature and oxygen is most likely facilitating ammonia dissociation. © 2004 Elsevier B.V. All rights reserved.

  • 87.
    Wicher, Bartosz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Warsaw Univ Technol, Poland.
    Chodun, Rafal
    Warsaw Univ Technol, Poland.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Lachowski, Artur
    Polish Acad Sci, Poland.
    Trzcinski, Marek
    Bydgoszcz Univ Sci & Technol, Poland.
    Pshyk, Oleksandr
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Krol, Krystian
    Warsaw Univ Technol, Poland.
    Kulikowski, Krzysztof
    Warsaw Univ Technol, Poland.
    Skowronski, Lukasz
    Bydgoszcz Univ Sci & Technol, Poland.
    Zdunek, Krzysztof
    Warsaw Univ Technol, Poland.
    Carbon ion self-sputtering attained by sublimation of hot graphite target and controlled by pulse injection of a neon-helium gas mixture2023Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 620, artikel-id 156708Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The operation of graphite targets with an increased temperature (HT - hot target) is studied for the case of gas injection magnetron sputtering (GIMS) of: 1) diamond-like carbon (DLC), and 2) carbon-silicon carbide (C-SiC) films. A purposely-thinned graphite target with a reduced thermal conductivity is applied for DLC deposition, extending its high temperature sputtering range up to 1636 degrees C. For the purpose of C-SiC synthesis four sockets with a silicon carbide powder are designed within graphite target. In this approach, the C-SiC target surface can be heated up to 1443 degrees C due to a greater energy input from impulse plasma, in the range 322-932 J. The HT sputtering is energy-controlled by a pulsed injection of a neon-helium gas mixture. High-energy Ne+ and He+ ions extend the length of pulsed GIMS discharge due to the self-sputtering effect observed during the deposition of DLC and C-SiC films. These conditions result in an almost 5-fold increase in the film growth rate (up to 185 nm/min) with respect to the operation with a cold target, which is due to the assisting vapour sublimation from custom-designed graphite-based targets. The temperature boosted HT GIMS discharge, proves to be an efficient tool for reaching relatively high (similar to 35 %) sp(3)-hybridized C content in both carbon-based materials. It also allows for tailoring the energy bandgap of DLC-based optical structure, in the range from 1.7 to 2.75 eV, due to the formation of the (C-C) and (C-O) bonds. Higher content of silicon oxide (SiO2-x) and silicon carbide (SiC) phases (15 - 23 %) in the case of C-SiC films results in hardness increase from 21.8 to 30.1 GPa.

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  • 88.
    Wongmanerod, C.
    et al.
    Department of Physics, Fac. Sci., Chulalongkorn U., Bangkok, Thailand.
    Zangooie, S.
    Department of Electrical Engineering, Ctr. Microlectron. Optical Mat. R., Lincoln, NE 68588-0511, United States.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Determination of pore size distribution and surface area of thin porous silicon layers by spectroscopic ellipsometry2001Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 172, nr 1-2, s. 117-125Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A non-destructive method for investigation of pore size distribution and surface area of porous silicon is presented. Adsorption and desorption isotherms of water in thin films of porous silicon are analyzed using variable angle of incidence spectroscopic ellipsometry. The analysis is based on multilayer optical models and the Bruggeman effective medium approximation. Pore size distribution and surface area are extracted from the isotherms employing the Wheeler theory combined with the Kelvin and Cohan equations. Good agreement is obtained between the calculated pore size distribution and estimations made by scanning electron microscopy. The evaluated specific surface area for the porous layers presented here is approximately 180 m2/cm3, which is in good agreement with the value reported in the literature.

  • 89.
    Wronkowska, A.A.
    et al.
    Instytut Matematyki i Fizyki, Akademia Techniczno-Rolnicza, Al. S. Kaliskiego 7, Bydgoszcz PL-85 796, Poland.
    Wronkowski, A.
    Instytut Matematyki i Fizyki, Akademia Techniczno-Rolnicza, Al. S. Kaliskiego 7, Bydgoszcz PL-85 796, Poland.
    Bukaluk, A.
    Instytut Matematyki i Fizyki, Akademia Techniczno-Rolnicza, Al. S. Kaliskiego 7, Bydgoszcz PL-85 796, Poland.
    Stefanski, M.
    Stefanski, M., Instytut Matematyki i Fizyki, Akademia Techniczno-Rolnicza, Al. S. Kaliskiego 7, Bydgoszcz PL-85 796, 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. Grudzia¸dzka 5, Torun PL-87 100, Poland.
    Legowski, S.
    L?gowski, S., Instytut Fizyki, Uniw. Mikolaja Kopernika, Ul. Grudzia¸dzka 5, Torun PL-87 100, Poland.
    Meczynska, H.
    M?czynska, H., Instytut Fizyki, Uniw. Mikolaja Kopernika, Ul. Grudzia¸dzka 5, Torun PL-87 100, Poland.
    Hradil, K.
    Universität Würzburg, Mineralogisches Institut, Am Hubland, Würzburg, Germany.
    Investigations of Cd1-xMnxTe crystals by means of ellipsometry and Auger electron spectroscopy2003Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 212-213, nr SPEC., s. 110-115Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Cd1-xMnxTe crystals, obtained by the high-pressure Bridgman method for x = 0, 0.27, 0.49, 0.67 and 0.8, were investigated. Crystal composition was determined by electron microprobe analysis. For an Mn content lower than 0.7, a single phase of pure zinc blend structure was found. In Cd0.2Mn0.8Te samples a two-phase structure was revealed. Auger electron spectroscopy (AES) was used to determine the composition of the crystal surfaces. AES depth profiles obtained by argon sputtering and AES analysis allowed to find the distribution of Cd, Mn and Te inside the sub-surface region. Spectroscopic ellipsometry was applied to determine the complex dielectric function e of the samples. Ellipsometric measurements were performed at room temperature in the photon energy range 0.75-6.5 eV. The spectral dependence of e was used to find the energy gaps Eg of the alloys with different Mn content. Ellipsometric data were correlated with the compositional results obtained from the electron microprobe and AES depth profile investigations. A linear increase of energy gaps with increasing x was observed for chemically homogeneous CdMnTe crystals. © 2003 Elsevier Science B.V. All rights reserved.

  • 90.
    Yang, Li-Li
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan. Institute of Condensed State Physics, Jilin Normal University, Siping, People's Republic of China.
    Zhao, Qingxiang
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Xianjie
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Fahlman, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Yang, J H
    Institute of Condensed State Physics, Jilin Normal University, Siping, People's Republic of China.
    Origin of the surface recombination centers in ZnO nanorods arrays by X-ray photoelectron spectroscopy2010Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 256, nr 11, s. 3592-3597Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The surface composition of as-grown and annealed ZnO nanorods arrays (ZNAs) grown by a two-step chemical bath deposition method has been investigated by X-ray photoelectron spectroscopy (XPS). XPS confirms the presence of OH bonds and specific chemisorbed oxygen on the surface of ZNAs, as well as H bonds on (1 0 (1) over bar 0) surfaces which has been first time observed in the XPS spectra. The experimental results indicated that the OH and H bonds play the dominant role in facilitating surface recombination but specific chemisorbed oxygen also likely affect the surface recombination. Annealing can largely remove the OH and H bonds and transform the composition of the other chemisorbed oxygen at the surface to more closely resemble that of high temperature grown ZNAs, all of which suppresses surface recombination according to time-resolved photoluminescence measurements.

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  • 91.
    Yang, L.L.
    et al.
    Jilin Normal University.
    Zhao, Qingxiang
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Xing, G.Z.
    Nanyang Technology University.
    Wang, D.D.
    Nanyang Technology University.
    Wu, T.
    Nanyang Technology University.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Gueorguiev Ivanov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Yang, J.H.
    Jilin Normal University.
    A SIMS study on Mg diffusion in Zn(0.94)Mg(0.06)O/ZnO heterostructures grown by metal organic chemical vapor deposition2011Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 257, nr 20, s. 8629-8633Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Zn(0.94)Mg(0.06)O/ZnO heterostructures have been grown on 2 in. sapphire wafer using metal organic chemical vapor deposition (MOCVD). Photoluminescence (PL) mapping demonstrates that Mg distribution on the entire wafer is very uniform (standard deviation of Mg concentration/mean Mg concentration = 1.38%) with average concentration of similar to 6%. The effect of annealing on the Mg diffusion in Zn(0.94)Mg(0.06)O/ZnO heterostructures has been investigated in detail by using secondary ion mass spectrometry (SIMS). All the Mg SIMS depth profiles have been fitted by three Gaussian distribution functions. The Mg diffusion coefficient in the as-grown Zn(0.94)Mg(0.06)O layer deposited at 700 degrees C is two orders of magnitude lower than that of annealed samples, which clearly indicates that the deposition temperature of 700 degrees C is much more beneficial to grow ZnMgO/ZnO heterostructures and quantum wells.

  • 92.
    Yazdi, Gholamreza
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Akhtar, Fatima
    IHP, Germany.
    Ivanov, Ivan Gueorguiev
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Schmidt, Susann
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Shtepliuk, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Zakharov, Alexei
    Lund Univ, Sweden.
    Iakimov, Tihomir
    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.
    Effect of epitaxial graphene morphology on adsorption of ambient species2019Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 486, s. 239-248Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work illustrates the impact of atmospheric gases on the surface of epitaxial graphene. The different rate of adsorption on different parts of graphene samples provides a concrete evidence that the surface morphology of graphene plays a significant role in this process. The uneven adsorption occurs only on the surface of the monolayer graphene and not on bilayer graphene. The second monolayer is distinguished and verified by the phase contrast mode of atomic force microscopy and the low energy electron microscopy, respectively. Raman spectroscopy is used to study the strain on the surface of graphene; results indicate that monolayer and bilayer graphene exhibit different types of strain. The bilayer is under more compressive strain in comparison with monolayer graphene that hinders the process of adsorption. However, the wrinkles and edges of steps of the bilayer are under tensile strain, hence, facilitate adsorption. Samples were subjected to X-ray photoelectron spectroscopy which confirms that the adsorbates on the epitaxial graphene are carbon clusters with nitrogen and oxygen contamination. For reversing the adsorption process the samples are annealed and a method for the removal of these adsorbates is proposed.

  • 93.
    Zhang, Hanmin
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Balasubramanian, T
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Univ Lund, Max Lab, S-22100 Lund, Sweden.
    Uhrberg, Roger
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik.
    Surface electronic structure of the root 3x root 3, root 39x root 39 and 6x6 surfaces of Ag/Ge(111): observation of a metal to semiconductor transition2001Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 175, s. 237-242Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Deposition of 1 monolayer (ML) of Ag on the clean Ge(1 1 1) surface, followed by annealing at 300 degreesC for 2 min, results in a sharp root3 x root3 low-energy electron diffraction (LEED) pattern. This surface transforms into a root 39 x root 39 surface, as observed by LEED, due to a tiny amount of additional Ag atoms when the temperature is below approximately -20 degreesC. The presence of the additional Ag leads to an increased filling of two partially occupied surface bands. By depositing approximately 0.2 ML of Ag on the root3 x root3 surface, it transforms into a 6 x 6 periodicity. The addition of Ag leads to an interesting transition from the metallic surfaces (root3 x root3 and root 39 x root 39) to the semiconducting 6 x 6 surface with a gap of around 0.2 eV with respect to the Fermi-level. On the 6 x 6 phase, the lower one of the partially occupied surface bands of the root3 x root3 and root 39 x root 39 surfaces seems to be entirely pulled down below the Fermi-level, while the upper one is missing. The electronic structures of the different Ag/Ge(111) surfaces an also discussed in comparison with the Ag/Si(111) surfaces. (C) 2001 Elsevier Science B.V. All rights reserved.

  • 94.
    Zhang, Hanmin
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Sakamoto, K
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Uhrberg, Roger
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Semiconductor-metal-semiconductor transition: valence band photoemission study of Ag/Si(111) surfaces2002Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 190, nr 1-4, s. 103-107Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The root3 x root3, root21 x root21 and 6 x 6 phases of Ag/Si(111) have been studied by angle-resolved photoemission and low-energy electron diffraction. The Ag/Si(111) root3 x root3 surface has an intrinsic semiconducting character with two fully occupied, dispersing surface state bands. We find that only one of the additional surface bands on the root21 x root21 surface is metallic in contrast to the two metallic bands discussed in the literature. On the 6 x 6 surface, the partially occupied surface band of the root21 x root21 surface seems to be absent, resulting in a gap of about 0.2 eV with respect to the Fermi-level. (C) 2002 Elsevier Science B.V. All rights reserved.

  • 95.
    Zhang, Hanmin
    et al.
    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 structures of Ag/Ge(1 1 1) v39 × v39 and 6 × 6 surfaces studied by STM: Observations of bias dependent reconstruction transformations2003Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 212-213, nr SPEC., s. 353-359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The 6 × 6 and v39 × v39 phases on Ag/Ge(1 1 1) have been studied by scanning tunneling microscopy (STM). Four types of 6 × 6 configurations are found which all consist of a v3 × v3 layer with six extra Ag adatoms per 6 × 6 unit cell. These reconstructions show either mirrored or complementary relations. We observe interesting transitions between the different 6 × 6 reconstructions. The v39 × v39 surface appears to have five extra Ag atoms per unit cell. By using various tip biases, we show that the v39 × v39 domain orientation can be changed. Surface structure models of the v39 × v39 and 6 × 6 phases are proposed based on the HCT structure of the underlying v3 × v3 surface. © 2003 Elsevier Science B.V. All rights reserved.

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