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  • 1. Aberg, D.
    et al.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Pellegrino, P.
    Svensson, B. G.
    Nitrogen passivation by implantation-induced point defects in 4H-SiC epitaxial layers2001In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 184, no 04-jan, p. 263-267Article in journal (Refereed)
    Abstract [en]

    Ion implantation causes damage to the crystal lattice resulting in the loss of free charge carriers. In this study, low dose implantations using different ions and implantation doses are made to resolve the initial carrier loss in nitrogen-doped epitaxial layers. A strong dependence of compensation on nitrogen concentration is seen, showing that nitrogen is passivated by implantation-induced point defects. An activation energy of 3.2 eV for the dissociation of the passivated nitrogen center is obtained.

  • 2. Agustsson, J. S.
    et al.
    Arnalds, U. B.
    Ingason, A. S.
    Gylfason, Kristinn B.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Johnsen, K.
    Olafsson, S.
    Gudmundsson, Jon Tomas
    University of Iceland, Iceland.
    Growth, coalescence, and electrical resistivity of thin Pt films grown by dc magnetron sputtering on SiO22008In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 254, no 22, p. 7356-7360Article in journal (Refereed)
    Abstract [en]

    Ultra thin platinum films were grown by dc magnetron sputtering on thermally oxidized Si (100) substrates. The electrical resistance of the films was monitored in situ during growth. The coalescence thickness was determined for various growth temperatures and found to increase from 1.1 nm for films grown at room temperature to 3.3 nm for films grown at 400 degrees C. A continuous film was formed at a thickness of 2.9 nm at room temperature and 7.5 nm at 400 degrees C. The room temperature electrical resistivity decreases with increased growth temperature, while the in-plain grain size and the surface roughness, measured with a scanning tunneling microscope (STM), increase. Furthermore, the temperature dependence of the film electrical resistance was explored at various stages during growth.

  • 3. Al Alawai, Reem
    et al.
    Laxman, karthik
    Dastgir, Sarim
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Sultan Qaboos University, , Oman.
    Role of bonding mechanisms during transfer hydrogenation reaction on heterogeneous catalysts of platinum nanoparticles supported on zinc oxide nanorods2016In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, p. 200-206Article in journal (Refereed)
    Abstract [en]

    For supported heterogeneous catalysis, the interface between a metal nanoparticle and the support plays an important role. In this work the dependency of the catalytic efficiency on the bonding chemistry of platinum nanoparticles supported on zinc oxide (ZnO) nanorods is studied. Platinum nanoparticles were deposited on ZnO nanorods (ZnO NR) using thermal and photochemical processes and the effects on the size, distribution, density and chemical state of the metal nanoparticles upon the catalytic activities are presented. The obtained results indicate that the bonding at Pt-ZnO interface depends on the deposition scheme which can be utilized to modulate the surface chemistry and thus the activity of the supported catalysts. Additionally, uniform distribution of metal on the catalyst support was observed to be more important than the loading density. It is also found that oxidized platinum Pt(IV) (platinum hydroxide) provided a more suitable surface for enhancing the transfer hydrogenation reaction of cyclohexanone with isopropanol compared to zero valent platinum. Photochemically synthesized ZnO supported nanocatalysts were efficient and potentially viable for upscaling to industrial applications.

  • 4. Alam, M. M.
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsén, P.
    Kaplan, A. F. H.
    Häggblad, H. A.
    The influence of surface geometry and topography on the fatigue cracking behaviour of laser hybrid welded eccentric fillet joints2010In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 256, no 6, p. 1936-1945Article in journal (Refereed)
    Abstract [en]

    Laser hybrid welding of an eccentric fillet joint causes a complex geometry for fatigue load by 4-point bending. The weld surface geometry and topography were measured and studied in order to understand the crack initiation mechanisms. The crack initiation location and the crack propagation path were studied and compared to Finite Element stress analysis, taking into account the surface macro-and micro-geometry. It can be explained why the root and the upper weld toe are uncritical for cracking. The cracks that initiate from the weld bead show higher fatigue strength than the samples failing at the lower weld toe, as can be explained by a critical radius for the toe below which surface ripples instead determine the main stress raiser location for cracking. The location of maximum surface stress is related to a combination of throat depth, toe radius and sharp surface ripples along which the cracks preferably propagate.

  • 5. Al-Hamdi, Abdullah M.
    et al.
    Sillanpaa, Mika
    Bora, Tanujjal
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Efficient photocatalytic degradation of phenol in aqueous solution by SnO2:Sb nanoparticles2016In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 370, p. 229-236Article in journal (Refereed)
    Abstract [en]

    Photodegradation of phenol in the presence of tin dioxide (SnO2) nanoparticles under UV light irradiation is known to be an effective photocatalytic process. However, phenol degradation under solar light is less effective due to the large band gap of SnO2. In this study antimony (Sb) doped tin dioxide (SnO2) nanoparticles were prepared at a low temperature (80 degrees C) by a sol-gel method and studied for its photo catalytic activity with phenol as a test contaminant. The catalytic degradation of phenol in aqueous media was studied using high performance liquid chromatography and total organic carbon measurements. The change in the concentration of phenol affects the pH of the solution due to the by-products formed during the photo-oxidation of phenol. The photoactivity of SnO2:Sb was found to be a maximum for 0.6 wt.% Sb doped SnO2 nanoparticles with 10 mg L-1 phenol in water. Within 2 h of photodegradation, more than 95% of phenol could be removed under solar light irradiation.

  • 6.
    Anghel, Clara
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Hörnlund, Erik
    KTH, Superseded Departments, Materials Science and Engineering.
    Hultquist, Gunnar
    KTH, Superseded Departments, Materials Science and Engineering.
    Limbäck, Magnus
    Gas phase analysis of CO interactions with solid surfaces at high temperatures2004In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 233, no 1-4, p. 392-401Article in journal (Refereed)
    Abstract [en]

    An in situ method including mass spectrometry and labeled gases is presented and used to gain information on adsorption of molecules at high temperatures (>300 degreesC). Isotopic exchange rate in H-2 upon exposure to an oxidized zicaloy-2 sample and exchange rate in CO upon exposure to various materials have been measured. From these measurements, molecular dissociation rates in respective system have been calculated. The influence of CO and N-2 on the uptake rate of H-2 in zirconium and oxidized zicaloy-2 is discussed in terms of tendency for adsorption at high temperatures. In the case of oxidized Cr exposed to CO gas With C-12, C-13, O-16 and O-18, the influence of H2O is investigated with respect to dissociation of CO molecules. The presented data supports a view of different tendencies for molecular adsorption of H2O, CO, N-2, and H-2 molecules on surfaces at high temperatures.

  • 7. Babonas, G. J.
    et al.
    Reza, A.
    Simkiene, I.
    Sabataityte, J.
    Baran, M.
    Szymczak, R.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Suchodolski, Arturas
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Optical properties of Fe-doped silica films on Si2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5391-5394Article in journal (Refereed)
    Abstract [en]

    Optical properties of Fe-doped silica films on Si were investigated by ellipsometric technique in the region 1-5 eV. Samples were produced by sol-gel method. Precursors were prepared by mixing tetraethoxysilane (TEOS) solution in ethanol and water with aqueous solution of Fe-chloride or Fe-acetate. The coating solution was deposited on Si substrates by spin on technique. The size of Fe-containing nanometric-sized particles depended on technology and varied from 20 to 100 nm. Optical response of complex hybrid samples SiO2:Fe/Si was interpreted in a multi-layer model. In the inverse problem, the Maxwell equations were solved by transfer matrix technique. Dielectric function of Fe-doped silica layers was calculated in the model of effective media. Analysis of optical data has shown that various Fe-oxides formed. Experimental data for films obtained from precursors with Fe-acetate and annealed in hydrogen were well described by the model calculations taking into account a small contribution 1-5% of metal Fe imbedded in silica. The Fe/Fe-O contribution to optical response increased for samples grown from FeCl3-precursor. Ellipsometric data for Fe-doped silica films on Si were interpreted taking into account the structural AFM studies as well as the results of magnetic measurements.

  • 8. Bexell, U.
    et al.
    Olsson, M.
    Sundell, P. E.
    Johansson, Mats K. G.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Carlsson, P.
    Hellsing, A.
    A ToF-SIMS study of linseed oil bonded to mercapto silane treated aluminium2004In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 231-2, p. 362-365Article in journal (Refereed)
    Abstract [en]

    ToF-SIMS has been used to analyse an aluminium surface treated with a vegetable oil using a mercapto silane as a coupling agent between the aluminium substrate and the vegetable oil. The coupling between the vegetable oil and the mercapto silane was obtained through a photoinduced thiol-ene reaction using UV-radiation. The ToF-SIMS results show that the desired thiolene reaction has taken place between the unsaturated parts of the vegetable oil and the thiol groups of the mercapto silane via the thiol-ene reaction forming a surface film.

  • 9. Beyhaghi, Maryam
    et al.
    Kiani-Rashid, Ali-Reza
    Kashefi, Mehrdad
    Khaki, Jalil Vandati
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Effect of powder reactivity on fabrication and properties of NiAl/Al2O3 composite coated on cast iron using spark plasma sintering2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 344, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Powder mixtures of Ni, NiO and Al are ball milled for 1 and 10 h. X-ray diffractometry and differential thermal analysis show that while ball milling for 1 h produced mechanically activated powder; 10 h ball milling produced NiAl and Al2O3 phases. Dense NiAl/Al2O3 composite coatings are formed on gray cast iron substrate by spark plasma sintering (SPS) technique. The effect of powder reactivity on microstructure, hardness and scratch hardness of NiAl/Al2O3 coatings after SPS is discussed. Results show that in the coating sample made of mechanically activated powder in situ synthesis of NiAl/Al2O3 composite coating is fulfilled and a thicker well-formed diffusion bond layer at the interface between coating and substrate is observed. The diffusion of elements across the bond layers and phase evolution in the bond layers were investigated. No pores or cracks were observed at the interface between coating layer and substrate in any of samples. Higher Vickers hardness and scratch hardness values in coating made of 10 h ball milled powder than in coating fabricated from 1 h ball milled powder are attributed to better dispersion of Al2O3 reinforcement particles in NiAl matrix and nano-crystalline structure of NiAl matrix. Scratched surface of coatings did not reveal any cracking or spallation at coating-substrate interface indicating their good adherence at test conditions.

  • 10. Bratus, V. Y.
    et al.
    Petrenko, T. T.
    von Bardeleben, H. J.
    Kalinina, E. V.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Vacancy-related defects in ion-beam and electron irradiated 6H-SiC2001In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 184, no 04-jan, p. 229-236Article in journal (Refereed)
    Abstract [en]

    A brief review is given on EPR study of irradiation-induced defects in SiC. The results of low-temperature study of Ky1 and Ky2 centers reveal for both of them the C-S symmetry, spin S = 1/2 and close coincidence of the g-tensor components. For Ky2 defect the principal values of g-tensor have been determined as g(z) = 2.0048, g(x) = 2.0022 and g(y) = 2.0037, where z and x directions reside in the (11 (2) over bar0) plane and the z-axis makes up an angle 65 degrees with the c-axis. The same residence of z- and x-axis and an angle 59 degrees are found for Ky1 center, g(z) = 2.0058, g(x) = 2.0025 and g(y) = 2.0023. A comparison of experimental and calculated hyperfine (HF) parameters is presented which suggests that Ky2 and Ky1 defects can be assigned to the positively charged carbon vacancy in 6H-SiC. The EPR study of defects created along the Al+ ion track in n-type 6H-SiC shows that lineshape, linewidth and integral intensity of the EPR signal reflect the state of damaged layer generated by ion implantation. A variation of defect density with annealing is reported and defect origin is discussed.

  • 11.
    Canestraro, Carla Daniele
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Oliveira, Marcela M.
    Departamento de Química, Universidade Federal do Paraná.
    Valaski, Rogerio
    Departamento de Física, Universidade Federal do Paraná.
    da Silva, Marcus V. S.
    Instituto de Física, Universidade Federal da Bahia.
    David, Denis G. F.
    Instituto de Física, Universidade Federal da Bahia.
    Pepe, Iuri
    Instituto de Física, Universidade Federal da Bahia.
    Ferreira da Silva, Antonio
    Instituto de Física, Universidade Federal da Bahia.
    Roman, Lucimara S.
    Departamento de Física, Universidade Federal do Paraná.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Strong inter-conduction-band absorption in heavily fluorine doped tin oxide2008In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 255, no 5, p. 1874-1879Article in journal (Refereed)
    Abstract [en]

    The optical, electrical and structural properties of thin. film tin oxide (TO), F-doped tin oxide (FTO; n(F) approximate to 6 x 10(20) cm (3)) and highly F-doped tin oxide (hFTO; n(F) approximate to 10 x 10(20) cm (3)), grown by spray pyrolysis technique, are studied by atomic force microscopy, Hall effect, X-ray. fluorescence and transmission/reflection measurements. The resistivity (rho = 32 x 10 (4) Omega cm for intrinsic tin oxide) shows intriguing characteristics when F concentration n(F) is increased (rho = 6 x 10 (4) Omega cm for FTO but 25 x 10 (4) Omega cm for hFTO) whereas the carrier concentration is almost constant at high F concentration (n(c) approximate to 6 x 10(20) cm (3) for FTO and hFTO). Thus, F seems to act both as a donor and a compensating acceptor in hFTO. The high carrier concentration has a strong effect on the optical band-edge absorption. Whereas intrinsic TO has room-temperature band-gap energy of E-g approximate to 3.2 eV with an onset to absorption at about 3.8 eV, the highly doped FTO and hFTO samples show relatively strong absorption at 2-3 eV. Theoretical analysis based on density functional calculations of FTO reveals that this is not a defect state within the band-gap region, but instead a consequence of a hybridization of the F donor states with the host conduction band in combination with a band. filling of the lowest conduction band by the free carriers. This allows photon-assisted inter-conduction band transitions of the free electrons to energetically higher and empty conduction bands, producing the below-gap absorption peak.

  • 12. Chaudhary, Shilpi
    et al.
    Kamra, Tripta
    Uddin, Khan Mohammad Ahsan
    Snezhkova, Olesia
    Jayawardena, H. Surangi N.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Montelius, Lars
    Schnadt, Joachim
    Ye, Lei
    Controlled short-linkage assembly of functional nano-objects2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 300, p. 22-28Article in journal (Refereed)
    Abstract [en]

    In this work, we report a method that allows the deterministic, photo-controlled covalent assembly of nanoparticles directly on surface. As a model system, we study the conjugation of molecularly imprinted polymer (MIP) nanoparticles on a glass surface and confirm that the immobilized nanoparticles maintain their molecular recognition functionality. The glass slide was first modified with perfluorophenylazide and then used to bind MIP nanoparticles under UV irradiation. After each step the surface was analyzed by water contact angle measurement, fluorescence microscopy, scanning electron microscopy, and/or synchrotron-based X-ray photoelectron spectroscopy. The MIP nanoparticles immobilized on the glass surface remained stable and maintained specific binding for the template molecule, propranolol. The method developed in this work allows MIP nanoparticles to be directly coupled to a flat surface, offering a straightforward means to construct robust chemical sensors. Using the reported photo conjugation method, it is possible to generate patterned assembly of nanoparticles using a photomask. Since perfluorophenylazide-based photochemistry works with all kinds of organic material, the method developed in this work is expected to enable immobilization of not only MIPs but also other kinds of organic and inorganic-organic core-shell particles for various applications involving photon or electron transfer.

  • 13.
    Cheng, Yajuan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Zhao, Zhe
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Controllable fabrication of large-area 2D colloidal crystal masks with large size defect-free domains based on statistical experimental design2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 313, p. 144-151Article in journal (Refereed)
    Abstract [en]

    A large-area hexagonal packed monolayer of silica spheres with consistent defect-free domains of a size larger than 3000 mu m(2) was prepared by spin coating on glass substrates with the assistance of experimental design and statistical analysis. The ratio of the defect-free monolayer area to the square of sphere diameter is nearly two times of the previously reported maximum values. Several parameters involved in the spin coating systems were investigated. The results indicated that the relative humidity and the rotational speed of the first step of the spin coating had the most important impact on the ordering degree of the prepared monolayer. Furthermore, the ordering degree of the obtained monolayer increased with a decreased relative humidity. In addition, it reached an optimal value when the first rotational speed during spin coating reached a value of 1000 rpm. From this study, it can be concluded that statistical experimental design is an efficient strategy, especially for multi-factor phenomenon studies.

  • 14.
    Cheng, Yajuan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Wang, Jing
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jösson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Zhao, Zhe
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Improvement and optimization of the growth quality of upright ZnOrod arrays by the response surface methodology2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 351, p. 451-459Article in journal (Refereed)
    Abstract [en]

    Response surface methodology was employed to guide the growth of ZnO rod arrays. With its assistance, the growth quality of the obtained samples was improved dramatically. The morphologies evolved from sparsely, randomly oriented rods to dense and upright rod arrays. Moreover, the significant parameters for ZnO rod arrays growth and their optimal regions were also determined. Furthermore, with the optimized parameters, the obtained aspect ratio of the vertically aligned ZnO rod arrays reached a value of 31. This is relatively a high value of ZnO rod arrays synthesized by wet chemical methods without capping agents in neutral solutions.

  • 15. Coullerez, G.
    et al.
    Lundmark, S.
    Malkoch, Michael
    KTH, Superseded Departments, Polymer Technology.
    Magnusson, H.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hult, Anders
    KTH, Superseded Departments, Polymer Technology.
    Mathieu, H. J.
    Insights into ToF-SIMS analysis of dendritic macromolecules: cationization and PCA to probe their molecular weight on surfaces2003In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 203, p. 620-624Article in journal (Refereed)
    Abstract [en]

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is utilized to study dendrons, dendrimers and hyperbranched derivatives prepared from the 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) or the 3-ethyl-3-(hydroxymethyl)oxetane (TMPO). We show that the cationization experiments of the intact molecules with alkali or metal ions such as Na+, Cu+ or Ag+ allow to detect whole molecular species up to 3000 Da (low generation). It allows to probe directly their molecular TM weight and end-functionality. However, when the molecule lift-off fails for series of hyperbranched polyesters Boltorn(TM), the fingerprint part of the SIMS spectra (m/z < 300 Da) is instead used. The low-mass fragments are mainly assigned to the bis-MP repeating unit. Ions due to the core molecule are also distinguished. Data treatment is combined with the principal component analysis (PCA) multivariate statistical method to highlight the main differences between the spectra. Only one principal component (PC1) is needed to describe most of the variance between the samples taking into account the generation effect. PC1 plotted as a function of the molecular weight gives a calibration curve. Normalization of the data set by ion intensities from the core molecule allows the linearization of the SIMS intensities vs. the molecular weight.

  • 16. da Silva, A. F.
    et al.
    Pepe, I.
    Gole, J. L.
    Tomas, S. A.
    Palomino, R.
    de Azevedo, W. M.
    da Silva, E. F.
    Ahuja, R.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Optical properties of in situ doped and undoped titania nanocatalysts and doped titania sol-gel nanofilms2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5365-5367Article in journal (Refereed)
    Abstract [en]

    In this paper we present spectroscopic properties of doped and undoped titanium dioxide (TiO2) as nanofilms prepared by the sol-gel process with rhodamine 6G doping and studied by photoacoustic absorption, excitation and emission spectroscopy. The absorption spectra of TiO2 thin films doped with rhodamine 6G at very low concentration during their preparation show two absorption bands, one at 2.3 eV attributed to molecular dimmer formation, which is responsible for the fluorescence quenching of the sample and the other at 3.0 eV attributed to TiO2 absorption, which subsequently yields a strong en-fission band at 600 nm. The electronic band structure and optical properties of the rutile phase of TiO2 are calculated employing a fully relativistic, full-potential, linearized, augmented plane-wave (FPLAPW) method within the local density approximation (LDA). Comparison of this calculation with experimental data for TiO2 films prepared for undoped sol-gels and by sputtering is performed.

  • 17. Davila, M. E.
    et al.
    Avila, J.
    Ascolani, H.
    Le Lay, G.
    Göthelid, Mats
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Karlsson, Ulf O.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Asensio, M. C.
    Surface phase transitions at metal-semiconductor interfaces: a revisit is needed2004In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 234, no 04-jan, p. 274-285Article in journal (Refereed)
    Abstract [en]

    In this article, we review some of the most recent progress and understanding in the low temperature surface phase transitions at prototypical metal-semiconductor interfaces. We essentially focus on quantitative surface structural information obtained by using a significant variety of specialised techniques for the individual phases of a model system, namely, tin on Ge(1 1 1) substrates. The strengths and limitations of the structural results obtained by using scanning tunnelling microscopy, photoelectron diffraction and surface X-ray diffraction are discussed in relation to their support with respect to possible mechanisms recently invoked in the literature as being at the origin of the phase transition. These investigations show that a large progress has been made in this field, taking into account the very valuable experimental and theoretical contributions provided by different groups. There remain, however, essential unresolved problems, which will be analysed in the light of the limitations of these structural methods and the difficulty presented by the complex adsorbate systems studied.

  • 18.
    Davoodi, Ali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Norgren, S.
    Sapa Technology, Finspång.
    Probing of local dissolution of Al-alloys in chloride solutions by AFM and SECM2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5499-5503Article in journal (Refereed)
    Abstract [en]

    Local dissolution of Al alloys was probed in situ in chloride solutions by using atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM). Preferential dissolution in the boundary region between some intermetallic particles (IMPs) and alloy matrix, and trench formation around large IMPs during free immersion and under electrochemical anodic polarization were observed, which indicate different dissolution behavior associated to different types of IMPs. Moreover, by using an integrated AFM/SECM system with a dual mode cantilever/microelectrode probe, simultaneous probing of electrochemical active sites and topographic changes over the same area was performed with submicron resolution. This allowed the ongoing localized corrosion processes related to the IMP to be revealed.

  • 19. Duch, J.
    et al.
    Kubisiak, P.
    Adolfsson, Karin H.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Golda-Cepa, M.
    Kotarba, A.
    Work function modifications of graphite surface via oxygen plasma treatment2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 419, p. 439-446Article in journal (Refereed)
    Abstract [en]

    The surface modification of graphite by oxygen plasma was investigated experimentally (X-ray diffraction, nanoparticle tracking analysis, laser desorption ionization mass spectrometry, thermogravimetry, water contact angle) and by molecular modelling (Density Functional Theory). Generation of surface functional groups (mainly –OHsurf) leads to substantial changes in electrodonor properties and wettability gauged by work function and water contact angle, respectively. The invoked modifications were analyzed in terms of Helmholtz model taking into account the theoretically determined surface dipole moment of graphite—OHsurf system (μ = 2.71 D) and experimentally measured work function increase (from 0.75 to 1.02 eV) to determine the –OH surface coverage (from 0.70 to 1.03 × 1014 groups cm−2). Since the plasma treatment was confined to the surface, the high thermal stability of the graphite material was preserved as revealed by the thermogravimetric analysis. The obtained results provide a suitable quantitative background for tuning the key operating parameters of carbon electrodes: electronic properties, interaction with water and thermal stability.

  • 20.
    Ejenstam, Lina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Tuominen, Mikko
    Haapanen, Janne
    Mäkelä, Jyrki M.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Swerin, Agne
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Long-term corrosion protection by a thin nano-composite coating2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584Article in journal (Refereed)
    Abstract [en]

    We report and discuss the corrosion protective properties of a thin nano-composite coating system consisting of an 11 μm thick polyester acrylate (PEA) basecoat, covered by an approximately 1 - 2 μm thick layer of TiO2 nanoparticles carrying a 0.05 μm thick hexamethyl disiloxane (HMDSO) top coat. The corrosion protective properties were evaluated on carbon steel substrates immersed in 3 wt% NaCl solution by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements. The protective properties of each layer, and of each pair of layers, were also evaluated to gain further understanding of the long term protective properties offered by the nano-composite coating. The full coating system showed excellent corrosion protective properties in the corrosive environment of 3 wt% NaCl-solution for an extended period of 100 days, during which the coating impedance, at the lower frequency limit (0.01 Hz), remained above 108 Ωcm2. We suggest that the excellent corrosion protective properties of the complete coating system is due to a combination of i) good adhesion and stability of the PEA basecoat, ii) the surface roughness and the elongated diffusion path provided by the addition of TiO2 nanoparticles, and iii) the low surface energy provided by the HMDSO top coat.

  • 21. Evertsson, J.
    et al.
    Bertram, F.
    Zhang, Fan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Rullik, L.
    Merte, L. R.
    Shipilin, M.
    Soldemo, Markus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Ahmadi, Sareh
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Vinogradov, N.
    Carla, F.
    Weissenrieder, Jonas
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Götelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Mikkelsen, A.
    Nilsson, J. -O
    Lundgren, E.
    The thickness of native oxides on aluminum alloys and single crystals2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 349, p. 826-832Article in journal (Refereed)
    Abstract [en]

    We present results from measurements of the native oxide film thickness on four different industrial aluminum alloys and three different aluminum single crystals. The thicknesses were determined using X-ray reflectivity, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. In addition, atomic force microscopy was used for micro-structural studies of the oxide surfaces. The reflectivity measurements were performed in ultra-high vacuum, vacuum, ambient, nitrogen and liquid water conditions. The results obtained using X-ray reflectivity and X-ray photoelectron spectroscopy demonstrate good agreement. However, the oxide thicknesses determined from the electrochemical impedance spectroscopy show a larger discrepancy from the above two methods. In the present contribution the reasons for this discrepancy are discussed. We also address the effect of the substrate type and the presence of water on the resultant oxide thickness.

  • 22. Ferraris, M.
    et al.
    Perero, S.
    Ferraris, S.
    Miola, M.
    Verne, E.
    Skoglund, Sara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden, Sweden.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Antibacterial silver nanocluster/silica composite coatings on stainless steel2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 396, p. 1546-1555Article in journal (Refereed)
    Abstract [en]

    A coating made of silver nanocluster/silica composites has been deposited, Via a radio frequency (RF) co-sputtering technique, for the first time onto stainless steel (AISI 304L) with the aim to improve its antibacterial properties. Different thermal treatments after coating deposition have been applied in order to optimize the coating adhesion, cohesion and its antibacterial properties. Its applicability has been investigated at realistic conditions in a cheese production plant. The physico-chemical characteristics of the coatings have been analyzed by means of different bulk and surface analytical techniques. Field emission scanning electron microscopy (FESEM), X-ray Photoelectron Spectroscopy (XPS), contact angle measurements and atomic force microscopy (AFM) were employed to assess coating morphology, composition, surface roughness, wetting properties, size and local distribution of the nanoparticles within the coating. Tape tests were used to determine the adhesion/cohesion properties of the coating. The amount and time-dependence of released silver in solutions of acetic acid, artificial water, artificial tap water and artificial milk were determined by means of Atomic Absorption Spectroscopy (AAS). The antibacterial effect of the coating was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus in compliance with National Committee for Clinical Laboratory Standards (NCCLS) and AATCC 147 standards. The Ahearn test was performed to measure the adhesion of bacteria to the coated stainless steel surface compared with a control surface. The antibacterial coating retained its antibacterial activity after thermal treatment up to 450 degrees C and after soaking in common cleaning products for stainless steel surfaces used for e.g. food applications. The antibacterial capacity of the coating remained at high levels for 1-5 days, and showed a good capacity to reduce the adhesion of bacteria up to 30 days. Only a few percent of silver in the coating was released into acetic acid, even after 10 days of exposure at 40 degrees C. Most silver (> 90%) remained also in the coating even after 240 h of continuous exposure. Similar observations were made after repeated exposure at 100 degrees C. Very low levels of released silver in solution were observed in artificial milk. No release of silver nanoparticles was observed either in synthetic tap water or in artificial milk at given conditions. The coating further displayed good antibacterial properties also when tested during working conditions in a cheese production plant.

  • 23.
    Ferraris, Sara
    et al.
    Politecnico di Torino.
    Perero, S.
    Politecnico di Torino.
    Miola, M.
    Politecnico di Torino.
    Vernè, E.
    Politecnico di Torino.
    Rosiello, A.
    Aero Sekur S.p.A.
    Ferrazzo, V.
    Aero Sekur S.p.A.
    Valletta, G.
    Aero Sekur S.p.A.
    Sanchez, Javier
    Bactiguard AB.
    Ohrlander, Mattias
    Bactiguard AB.
    Tjörnhammar, Staffan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Fokine, Michael
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, Sweden.
    Skoglund, Sara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ferraris, M.
    Politecnico di Torino.
    Chemical, mechanical and antibacterial properties of silver nanocluster/silica composite coated textiles for safety systems and aerospace applications2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 317, p. 131-139Article in journal (Refereed)
    Abstract [en]

    This work describes the chemical, mechanical and antibacterial properties of a novel silver nanocluster/silica composite coating, obtained by sputtering, on textiles for use in nuclear bacteriological and chemical (NBC) protection suites and for aerospace applications.

    The properties of the coated textiles were analyzed in terms of surface morphology, silver concentration and silver release in artificial sweat and synthetic tap water, respectively. No release of silver nanoparticles was observed at given conditions.

    The water repellency, permeability, flammability and mechanical resistance of the textiles before and after sputtering demonstrated that the textile properties were not negatively affected by the coating.

    The antibacterial effect was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus and compared with the behavior of uncoated textiles.

    The coating process conferred all textiles a good antibacterial activity. Optimal deposition conditions were elaborated to obtain sufficient antibacterial action without altering the aesthetical appearance of the textiles.

    The antibacterial coating retained its antibacterial activity after one cycle in a washing machine only for the Nylon based textile.

  • 24. Gothelid, M
    et al.
    LeLay, G
    Wigren, C
    Bjorkqvist, M
    Rad, M
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Etching and a disordered overlayer on the Ge(100)-S surface1997In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 115, no 1, p. 87-95Article in journal (Refereed)
    Abstract [en]

    High resolution core level photoelectron spectroscopy (PES) and scanning tunneling microscopy (STM) have been used to study the adsorption and desorption of S on and off the Ge(100) surface. The previously proposed bridge adsorption site of S is consistent with our results at low coverage. At saturation the substrate contains several GeSx species, with x = 0.5 to 4. Both photoemission and STM reveals a non-ideal surface, with a saturation coverage above one monolayer. Furthermore, S is found to etch the substrate. The reaction products forms a disordered overlayer on top of the interface. This overlayer is transparent in the filled state STM images.

  • 25. Gothelid, M
    et al.
    Odasso, S
    LeLay, G
    Bjorkqvist, M
    Janin, E
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Grehk, T M
    Ge/(111)3x1:K/Sn; On the influence of tin substitution in a metal induced 3x1 reconstruction1996In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 104, p. 113-117Article in journal (Refereed)
    Abstract [en]

    Go-adsorption of tin and potassium is found to induce a 3x1 reconstruction on the Ge(lll) surface. A very small amount of tin influences the Ge 3d core level spectra substantially compared to the Ge(111)3x1:K reconstruction. This is interpreted as resulting from a relaxation of the strain in the rows Ge atoms running along the surface, as proposed for this structure.

  • 26.
    Göthelid, Mats
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Material Physics, MF.
    Hosseinpour, S.
    Ahmadi, S.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Johnson, C. Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hexane selenol dissociation on Cu: The protective role of oxide and water2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 423, p. 716-720Article in journal (Refereed)
    Abstract [en]

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

  • 27.
    Haralson, Erik
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Suvar, Erdal
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Malm, B. Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Radamson, Henry H.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Wang, Yong-Bin
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Östling, Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    The effect of C on emitter-base design for a single-polysilicon SiGe: C HBT with an IDP emitter2004In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 224, no 1-4, p. 330-335Article in journal (Refereed)
    Abstract [en]

    A differential epitaxy SiGe:C heterojunction bipolar junction transistor (HBT) design is reported and used to study the effect of carbon on junction formation as well as the effect of lateral design parameters on ac and dc performance. The device exhibits a high current gain (beta) of 1700 and a BVCEO of 1.8 V. The peak cutoff frequency (f(T)) and maximum oscillation frequency (f(MAX)) are 73 and 17 GHz, respectively. The effect of emitter overlap on f(T) was minimal, but it had a strong impact on dc performance. LOCOS opening size strongly impacted both ac and dc performance. In addition, the effect of carbon, base cap thickness, and rapid thermal anneal (RTA) temperature on the emitter-base (E-B) junction formation was studied.

  • 28.
    He, Yunjuan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Dobryden, Illia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Ahniyaz, Anwar
    RISE Res Inst Sweden, Div Biosci & Mat, SE-11486 Stockholm, Sweden..
    Deltin, Tomas
    PTE Coatings AB, Hammarsvagen 4, SE-59432 Gamleby, Sweden..
    Corkery, Robert W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Nano-scale mechanical and wear properties of a waterborne hydroxyacrylic-melamine anti-corrosion coating2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 457, p. 548-558Article in journal (Refereed)
    Abstract [en]

    Corrosion protection is commonly achieved by applying a thin polymer coating on the metal surface. Many studies have been devoted to local events occurring at the metal surface leading to local or general corrosion. In contrast, changes occurring in the organic coating after exposure to corrosive conditions are much less studied. In this article we outline how changes in the coating itself due to curing conditions, environmental and erosion effects can be investigated at the nanometer scale, and discuss how such changes would affect its corrosion protection performance. We focus on a waterborne hydroxyacrylic-melamine coating, showing high corrosion protection performance for carbon steel during long-term (approximate to 35 days) exposure to 0.1 M NaCl solution. The effect of curing time on the conversion of the crosslinking reaction within the coating was evaluated by fourier transform infrared spectroscopy (FTIR); the wetting properties of the cured films were investigated by contact angle measurement, and the corrosion resistance was studied by electrochemical impedance spectroscopy (EIS). In particular, coating nanomechanical and wear properties before and after exposure to 0.1 M NaCl, were evaluated by atomic force microscopy (AFM). Fiber-like surface features were observed after exposure, which are suggested to arise due to diffusion of monomers or low molecular weight polymers to the surface. This may give rise to local weakening of the coating, leading to local corrosion after even longer exposure times. We also find a direct correlation between the stick-slip spacing during shearing and plastic deformation induced in the surface layer, giving rise to topographical ripple structures on the nanometer length scale.

  • 29. He, Z Q
    et al.
    Ilver, L
    Kanski, J
    Nilsson, P O
    Songsiriritthigul, P
    Holmen, G
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Band structure evolution in InAs overlayers on GaAs(110)1996In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 104, p. 608-614Article in journal (Refereed)
    Abstract [en]

    An angle-resolved photoemission study of MBE grown InAs/GaAs(110) hetero-structures was carried out to investigate the establishment of valence bands as a function of overlayer thickness. The valence band spectra were found to change gradually up to thicknesses well above 10 nm. The data are interpreted in terms of excitations within the overlayer from a combination of substrate and overlayer initial states, the former tailing into the overlayer.

  • 30. Hellsing, M
    et al.
    Fokine, Michael
    Claesson, A
    Nilsson, E
    Margulis, Walter
    ToF-SIMS imaging of dopant diffusion in optical fibers2003In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 203, p. 648-651Article in journal (Refereed)
    Abstract [en]

    Applications of optical fibers in telecommunication and sensing are rapidly emerging where the fiber properties are related to the controlled addition of dopants such as germanium, phosphorous, fluorine and erbium. The modern ToF-SIMS instrument, with its high sensitivity and high lateral resolution, has shown to be an excellent tool to directly analyze cross-sections of as-manufactured fibers. The present work describes ToF-SIMS imaging of the dopant distribution in fluorine, germanium and rare-earth doped fibers where dopants are confined to a few mum in the core. The increased fluorine diffusion in the fluorine doped fibers due to chemical reactions with hydroxyl groups was examined. This process is utilized in the manufacture of thermally stable chemical composition fiber Bragg gratings. We were able to produce ToF-SIMS elemental images with a lateral resolution around 0.5 mum showing the detailed distribution of the dopants.

  • 31. Hirschauer, B
    et al.
    Gothelid, M
    Janin, E
    Lu, H
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    CeO2 on Si(111) 7 X 7 and Si(111)-H 1 X 1, an interface study by high-resolution photoelectron spectroscopy1999In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 148, no 3-4, p. 164-170Article in journal (Refereed)
    Abstract [en]

    The formation of the CeO2-Si(111) interface was studied by high-resolution photoelectron spectroscopy. It is shown that CeO2 and Si(111) forms a highly reactive: interface with a strong interdiffusion of Si into the CeO2. A passive silicon surface formed by saturating the Si dangling bonds with hydrogen is considerably less reactive. Defects on the surface, however, act as nucleations centres for reactions of a Si:Ce:O matrix. Oxygen leaves the surface at about 800 degrees C and at 1000 degrees C a surface reconstruction of Si(111)-Ce 2 X 2/root 3 X root 3 is formed. (C) 1999 Elsevier Science B.V. All rights reserved.

  • 32.
    Hussain, T.
    et al.
    Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia..
    Singh, D.
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden.;SV Natl Inst Technol, Dept Appl Phys, Adv Mat Lab, Surat 395007, Gujarat, India..
    Gupta, Sanjeev K.
    St Xaviers Coll, Dept Phys, Computat Mat & Nanosci Grp, Ahmadabad 380009, Gujarat, India..
    Karton, A.
    Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia..
    Sonvane, Yogesh
    SV Natl Inst Technol, Dept Appl Phys, Adv Mat Lab, Surat 395007, Gujarat, India..
    Ahuja, R.
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden.;Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Efficient and selective sensing of nitrogen-containing gases by Si2BN nanosheets under pristine and pre-oxidized conditions2019In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 469, p. 775-780Article in journal (Refereed)
    Abstract [en]

    Motivated by the promise of two-dimensional nanostructures in the field of gas sensing, we have employed van der Waals corrected density functional theory calculations to study the structural, electronic and gas sensing propensities of the recently designed Si2BN monolayer. Our rigorous simulations reveal that the representative members of nitrogen-containing gases (NCGs) such as NO, NO2 and NH3 binds extremely strongly on pristine Si2BN monolayer. However, a strong dissociative adsorption in case of NO and NO2 would poison the Si2BN and ultimately reversibility of the monolayer would be compromised. Exploring the sensing mechanism in more realistic pre-oxidized conditions, the binding characteristics of O-2@Si2BN changed dramatically, resulting into much lower adsorption in associative manner for all NO, NO2 and NH3. A visible change in work function indicates the variation in conductivity of O-2@Si2BN upon the exposure of incident gases. Sustainable values of binding energies would also ensure a quick recovery time that makes O-2@Si2BN an efficient nano sensor for pollutants like NCGs.

  • 33.
    Hussain, T.
    et al.
    Univ Queensland, Australian Inst Bioengn & Nanotechnol, Ctr Theoret & Computat Mol Sci, Brisbane, Qld 4072, Australia.;Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia..
    Vovusha, H.
    KAUST, Phys Sci & Engn Div PSE, Thuwal 239556900, Saudi Arabia.;Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Umer, R.
    Univ Southern Queensland, Ctr Future Mat, Toowoomba, Qld 4350, Australia..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Superior sensing affinities of acetone towards vacancy induced and metallized ZnO monolayers2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 456, p. 711-716Article in journal (Refereed)
    Abstract [en]

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

  • 34.
    Hållstedt, Julius
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Suvar, Erdal
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Persson, P. O. Å.
    Department of Physics, Thin Film Physics Division, Linköpings Universitet.
    Hultman, L.
    Department of Physics, Thin Film Physics Division, Linköpings Universitet.
    Wang, Yong-Bin
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Radamson, Henry H.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Growth of high quality epitaxial Si1-x-yGexCy layers by using chemical vapor deposition2004In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Applied Surface Science, Vol. 224, no 1-4, p. 46-50Article in journal (Refereed)
    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.

  • 35. Intarasiri, S.
    et al.
    Hallén, Anders.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lu, J.
    Jensen, J.
    Yu, L. D.
    Bertilsson, K.
    Wolborski, M.
    Singkarat, S.
    Possnert, G.
    Crystalline quality of 3C-SiC formed by high-fluence C+-implanted Si2007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 253, no 11, p. 4836-4842Article in journal (Refereed)
    Abstract [en]

    Carbon ions at 40 keV were implanted into (1 0 0) high-purity p-type silicon wafers at 400 degrees C to a fluence of 6.5 x 10(17) ions/cm(2). Subsequent thermal annealing of the implanted samples was performed in a diffusion furnace at atmospheric pressure with inert nitrogen ambient at 1100 degrees C. Time-of-flight energy elastic recoil detection analysis (ToF-E ERDA) was used to investigate depth distributions of the implanted ions. Infrared transmittance (IR) and Raman scattering measurements were used to characterize the formation of SiC in the implanted Si substrate. X-ray diffraction analysis (XRD) was used to characterize the crystalline quality in the surface layer of the sample. The formation of 3C-SiC and its crystalline structure obtained from the above mentioned techniques was finally confirmed by transmission electron microscopy (TEM). The results show that 3C-SiC is directly formed during implantation, and that the subsequent high-temperature annealing enhances the quality of the polycrystalline SiC.

  • 36. Janin, E
    et al.
    Bjorkqvist, M
    Grehk, T M
    Gothelid, M
    Pradier, C M
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Rosengren, A
    Hydrogen adsorption on the Pt(111)(root 3x root 5)R30 degrees-Sn surface alloy studied by high resolution core level photoelectron spectroscopy1996In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 99, no 4, p. 371-378Article in journal (Refereed)
    Abstract [en]

    Investigation of the clean and atomic hydrogen covered Pt(111)(root 3 x root 3)R30 degrees-Sn surface alloy has been carried out using high resolution core level photoelectron spectroscopy, The Pt 4(7/2) spectrum recorded from the clean surface alloy shows a single surface peak shifted - 0.25 eV relative to the bulk. Its interpretation by means of a thermodynamical model using Born-Haber cycles confirms the surface alloy model. Adsorption of H does not change the line shape of the Sn 4d core level while a new surface component shifted by 0.59 eV compared to the bulk peak appears in the Pt 4(7/2) spectrum. These results are discussed in the light of the thermodynamical calculations, H atoms are believed to bind only to Pt atoms, and their adsorption site seems to be influenced by the tin present in the surface layer.

  • 37. Janin, E.
    et al.
    Göthelid, Mats
    KTH, Superseded Departments, Materials Science and Engineering.
    Karlsson, U. O.
    Formation of two-dimensional graphite islands on the Pt(110)(1x2) surface2000In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 162, p. 184-189Article in journal (Refereed)
    Abstract [en]

    The formation of thin carbon overlayers at temperatures above 600 degrees C has been studied on the Pt(110)(1 X 2) surface by Scanning Tunneling Microscopy (STM), PES and Low-Energy Electron Diffraction (LEED). Their graphitic character is evidenced through the binding energy of the Cls core-level, the LEED pattern observed and the atomic structure resolved on the islands. The orientation of the graphite layers is determined to be C < 1010 > parallel to the Pt[110] direction. Their thickness and the nature of the substrate are discussed below.

  • 38. Janson, M. S.
    et al.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Linnarsson, Margareta K
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, B. G.
    Hydrogen-boron complex formation and dissociation in 4H-silicon carbide2001In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 184, no 04-jan, p. 257-262Article in journal (Refereed)
    Abstract [en]

    The diffusion of deuterium (H-2) in p-type 4H-silicon carbide (SiC) has been studied in detail by secondary ion mass spectrometry. An effective capture radius for the formation of H-2-B complexes at 460 degreesC is determined to R-HB = (21 +/- 4) A. This value is in good agreement with that expected for a coulomb force-assisted trapping mechanism. At higher temperatures, the H-2 diffusion follows Fick's law with a constant effective diffusivity from which the complex dissociation frequencies nu (HB) are determined. The frequencies exhibit an Arrhenius temperature dependence over the three orders of magnitude covered by the extracted nu (HB). The complex dissociation energy is determined to E-d(HB) = (2.51 +/- 0.04) eV which is 0.9 eV larger than the corresponding value for the H-2-Al complex, suggesting that the atomic configurations for the two complexes are significantly different. The extracted dissociation attempt frequency, nu (HB)(0) = (1.2 +/- 0.7) x 10(13) s(-1) is very close to the characteristic oscillation frequency of the SiC lattice, nu (SiC)(lattice) = 1.6 x 10(13) s(-1). In addition, H-2 diffusion in an epitaxial AI multilayer structure demonstrates the influence of internal electric fields on the H-2 diffusion in p-type SiC.

  • 39.
    Jovanovic, Aleksandar
    et al.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.;Oberflachentechnol GmbH, CEST Kompetenzzentrum Elektrochem, Viktor Kaplan Str 2,Sect A, A-2700 Wiener Neustadt, Austria..
    Petkovic, Milena
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Pasti, Igor A.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala Univ, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden.;Humboldt Univ, Phys Dept, Zum Grossen Windkanal 6, D-12489 Berlin, Germany..
    Skorodumova, Natalia
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala Univ, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden..
    Tuning the electronic and chemisorption properties of hexagonal MgO nanotubes by doping - Theoretical study2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 457, p. 1158-1166Article in journal (Refereed)
    Abstract [en]

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

  • 40. Kalinina, E.
    et al.
    Kholujanov, G.
    Solov'ev, V.
    Strel'chuk, A.
    Kossov, V.
    Yafaev, R.
    Kovarskii,
    Shchukarev, A.
    Obyden, S.
    Saparin, G.
    Ivannikov, P.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Konstantinov, A.
    Influence of ion implantation on the quality of 4H-SiC CVD epitaxial layers2001In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 184, no 04-jan, p. 323-329Article in journal (Refereed)
    Abstract [en]

    The effect of ion implantation doping (ID) with high doses of Al followed by short high-temperature annealing of n-type 4H-SiC epitaxial layers grown by chemical vapor deposition (CVD) has been studied. The comparative investigations of the structural and electrical properties, lateral and as a function of depth, in the CVD layers before and after Al ID p(+)n junction formations were determined by several different methods. Structural improvement of the CVD epitaxial layers close to Al ID p(+)n junction positions was revealed for the first time.

  • 41.
    Karlsson, Ulf O.
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101).
    Wäppling, Roger
    Preface: ACSIN8/ICTF13 - Proceedings of the Eighth International Conference on Atomically Controlled Surfaces, Interfaces and Nanostructures and the Thirteenth International Congress on Thin Films - Stockholm, Sweden, June 20-23, 20052006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5243-Article in journal (Refereed)
  • 42. Karpus, V.
    et al.
    Suchodolskis, Arturas
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Lay, G.
    Giovanelli, L.
    Assmus, W.
    Bruhne, S.
    Uhrig, E.
    Mg 2p shallow core-level and local atomic structure of i-ZnMgRE quasicrystals2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5411-5414Article in journal (Refereed)
    Abstract [en]

    We present a detailed analysis of the Mg 2p shallow core-levels measured on icosahedral single-grain ZnMgY, ZnMgHo, and ZnMgEr quasicrystals during a photoelectron microscopy study. The synchrotron radiation photoemission measurements were performed on in situ cleaved samples at a pressure of 10(-10) mbar and at low temperature, typically 90-150 K. The Mg 2p photoemission lines are essentially broadened as compared to those of the Mg 2p spin-orbit doublet recorded on the Zn2Mg crystalline Laves phase. The broadening is associated to the coordination shifts of the Mg 2p level due to the inequivalent magnesium sites in the quasicrystalline lattice. The coordination shifts are calculated on the basis of i-ZnMg(Ho, Y) atomic structure data, recently determined from the pair distribution function analysis. The coordination shifts obtained are up to 0.2 eV. The Mg 2p experimental spectral intensity is nicely reproduced by a superposition of coordination-shifted Mg 2p spin-orbit doublets.

  • 43. Kleber, C.
    et al.
    Weissenrieder, Jonas
    KTH, Superseded Departments, Materials Science and Engineering.
    Schreiner, M.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Comparison of the early stages of corrosion of copper and iron investigated by in situ TM-AFM2002In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 193, no 1-4, p. 245-253Article in journal (Refereed)
    Abstract [en]

    Tapping mode atomic force microscopy (TM-AFM) was used for the investigation of the early stages of atmospheric corrosion of pure copper and pure iron. The information obtained by this method is the change of the topography of the sample surfaces with emphasis on the. shape and lateral distribution of the corrosion products grown within the first 1300 min of weathering. Investigations were carried out in synthetic air at 80 and 90% relative humidity (RH) with additions of 250 ppb SO2 and 250 ppb NO2. On a polished copper surface the growth of corrosion products could be observed already at 80% RH and 250 ppb SO2, whereas an iron surface had to be exposed to 90% RH with 250 ppb SO2 and 250 ppb NO, to produce detectable changes on the surface.

  • 44.
    Laxman, Kunjali Karthik
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Al Rashdi, M.
    Al Sabahi, J.
    Al Abri, M.
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Supported versus colloidal zinc oxide for advanced oxidation processes2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 411, p. 285-290Article in journal (Refereed)
    Abstract [en]

    Photocatalysis is a green technology which typically utilizes either supported or colloidal catalysts for the mineralization of aqueous organic contaminants. Catalyst surface area and surface energy are the primary factors determining its efficiency, but correlation between the two is still unclear. This work explores their relation and hierarchy in a photocatalytic process involving both supported and colloidal catalysts. In order to do this the active surface areas of supported zinc oxide nanorods (ZnO NR's) and colloidal zinc oxide nanoparticles (having different surface energies) were equalized and their phenol oxidation mechanism and capacity was analyzed. It was observed that while surface energy had subtle effects on the oxidation rate of the catalysts, the degradation efficiency was primarily a function of the surface area; which makes it a better parameter for comparison when studying different catalyst forms of the same material. Thus we build a case for the use of supported catalysts, wherein their catalytic efficiency was tested to be unaltered over several days under both natural and artificial light, suggesting their viability for practical applications.

  • 45. Le Lay, G.
    et al.
    Rad, M. G.
    Göthelid, Mats
    KTH, Superseded Departments, Materials Science and Engineering.
    Karlsson, Ulf O.
    KTH, Superseded Departments, Physics.
    Avila, J.
    Asensio, M. C.
    Nature of the root 3 alpha to 3 x 3 reversible phase transition at low temperature in Sn/Ge (111)2001In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 175, p. 201-206Article in journal (Refereed)
    Abstract [en]

    Metal-induced superstructures on semiconductors at sub-monolayer coverages have been mostly studied at, or above, room temperature. Yet, recently, several reversible phase transitions, like, e.g. the root3 x root3 alpha to 3 x 3 transition in the Pb, Sn/Ge (111) prototypical systems, have been discovered below RT. The origin of these new reconstructions is very intriguing and is a matter of strong debate. Some groups privilege electronic instabilities leading to charge ordered states at low temperature (LT), while other favor dynamical effects and the formation a kind of bond density waves (BDW's) at LT. Besides these intrinsic behaviors, the role played by inevitable defects has also been emphasized by several authors. Focussing especially on the Sn/Ge (111) system, we present a detailed analysis of the spectroscopic signatures of each phase in photoemission measurements. We show that static models are impossible to reconcile with these measurements.

  • 46. LELAY, G
    et al.
    ARISTOV, VY
    KANSKI, J
    NILSSON, PO
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    HRICOVINI, K
    BONNET, JE
    ELECTRONIC-PROPERTIES OF CLEAVED(110) AND MBE-GROWN(100) INAS SURFACES, CLEAN AND COVERED WITH AN ULTRA-THIN AG ADLAYER1993In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 70-1, p. 502-506Article in journal (Refereed)
    Abstract [en]

    The initial electronic structure of the pseudomorphic InAs/GaAs(100) heterostructure as well as that of the Ag/InAs(110) interface at 20 K have been studied by synchrotron radiation photoelectron spectroscopy. In the first case we find that the valence band spectra show no evidence for the formation of bulk-like energy bands. In the second case we prove for the first time that upon deposition of minute amounts of Ag at low temperature onto cleaved InAs(110) substrates one induces a giant movement of the Fermi level well into the conduction band thus creating a strong two-dimensional electron channel at the surface.

  • 47. LELAY, G
    et al.
    KANSKI, J
    NILSSON, PO
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    CORE-LEVEL SPECTROSCOPY STUDY OF THE INITIAL FORMATION OF TIN GERMANIUM INTERFACES1992In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 56-8, p. 178-184Article in journal (Refereed)
    Abstract [en]

    We have studied the initial stages of the Schottky barrier formation at Sn/Ge(100) interfaces, in comparison with Sn/Ge(111) ones, with high resolution core-level spectroscopy measurements (Ge 3d and Sn 4d shallow core levels) using synchrotron radiation. A detailed, stringent decomposition of the core lines reveals three different components for both Ge and Sn on the two surfaces. The three components of the Sn 4d line on the Ge(100)2 x 1-Sn surface are interpreted as due to three different adsorption sites simultaneously occupied, while the persistence of the surface components in the Ge 3d core lines suggests that the building block of the reconstruction remains an asymmetric Ge dimer.

  • 48.
    Levin, Martina
    et al.
    Nynas AB.
    Wiklund, Per
    Nynas AB.
    Arwin, Hans
    Linköping University.
    Adsorption and film growth of N-methylamino substituted triazoles on copper surfaces in hydrocarbon media2007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 254, no 5, p. 1528-1533Article in journal (Refereed)
    Abstract [en]

    The adsorption of benzotriazole (BTA), tolyltriazole (TTA) and two different N-methylaminosubstituted triazoles on copper surfaces in hydrocarbon media has been examined by in situ ellipsometry and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). All four triazoles were found to form films and from the ellipsometric study were the film thicknesses estimated to be in the range of 0.5-2 nm after 1000 min exposure time. The layers formed from BTA and TTA were thicker (up to 2 nm) than the layers from N-aminomethyl substituted triazoles (roughly 0.5 nm). Desorption was studied qualitatively and 20% or less of the adsorbed material were found to desorb. The ToF-SIMS study showed that while BTA and TTA adsorbed intact did the N-aminomethyl substituted triazoles appear to loose their aminomethyl tails on binding since only signals corresponding to triazole moieties of the compounds were detected.

  • 49.
    Linnarsson, Margareta K.
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Janson, Martin S.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Nordell, Nils
    KTH, School of Information and Communication Technology (ICT), Centres, Electrum Laboratory, ELAB.
    Wong-Leung, J.
    Schoner, A.
    Formation of precipitates in heavily boron doped 4H-SiC2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5316-5320Article in journal (Refereed)
    Abstract [en]

    Secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM) are utilized to study precipitation and the solubility of B in 4H-SiC epitaxial layers super saturated with B. Heat treatments are performed in Ar atmosphere in an rf-heated furnace at temperatures between 1700 and 2000 degrees C. SIMS ion images, and TEM micrographs reveal the formation of two types of precipitates where the larger, more thermally stable one is suggested to be B4C. The boron solubility is determined from SIMS depth profiles and is shown to follow the Arrhenius expression: 7.1 x 10(22) exp(-1.4 eV/k(B)T) cm(-3) over the studied temperature range.

  • 50.
    Linnarsson, Margareta K.
    et al.
    KTH, Superseded Departments, Electronics.
    Svensson, B. G.
    KTH, Superseded Departments, Electronics.
    Andersson, T. G.
    Wang, S. M.
    Paska, Z. F.
    Sputter profiling of AlGaAs/GaAs superlattice structures using oxygen and argon ions1993In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 70-71, no 1, p. 40-43Article in journal (Refereed)
    Abstract [en]

    Broadening of Al sputter profiles in AlxGa1-xAs/GaAs structures has been investigated using secondary ion mass spectrometry. The depth profiling was carried out with 32O+2 ions and 40Ar+ ions using net primary energies of 1.8, 2.2, 3.2 and 5.7 keV. The decay lengths of the Al profiles show a pronounced increase with increasing sputtering ion energy caused by ballistic mixing. Moreover, in the O+2 case the λ-values degrade with eroded depth, indicating that beam-induced surface roughening takes place during profiling and in particular, this holds for high x-values. The results are discussed in terms of a semi-empirical model for ion-beam-induced broadening developed by Zalm and Vriezema.

12 1 - 50 of 90
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