SwePub - sökning: L773:0040 6090

Numrering	Referens	Omslagsbild	Hitta
1.	Chirita, V, et al. (författare) Strain relaxation and thermal stability of the 3C-SiC(001)/Si(001) interface : A molecular dynamics study 1997 Ingår i: Thin Solid Films. - 0040-6090. ; 294:1-2, s. 47-49 Tidskriftsartikel (refereegranskat)abstract Molecular dynamics (MD) and high-resolution electron microscopy (HREM) imaging are used to investigate the mechanism of strain relaxation of a model 3C-SiC(001)/Si(001) interface. It is found that the essential atomic mechanism governing this process is the formation of undulations in planes parallel and perpendicular to the interface. The net effect is the generation of misfit-accommodating dislocations, of the [removed] type, which allow for structure relaxation at 2, 700 and 1000 K. MD configurations are then used for HREM image simulations. Comparisons with actual HREM images of the interface support the model interface and relaxation mechanisms proposed herein.
2.	Krupin, OW, et al. (författare) Ferrimagnetic 4f spin order in O/Gd surface monoxide 2003 Ingår i: Thin Solid Films. - 0040-6090. ; 428:1-2, s. 98-101 Tidskriftsartikel (refereegranskat)abstract The remanent 4f spin structure of the epitaxial surface monoxide O(1 X 1)/Gd(0001) has been investigated using magnetic dichroism in core-level photoemission (MDPE). Here we report the observation of a substantial dichroic signal of the chemically shifted Gd-4f PE line. It demonstrates the presence of a non-vanishing net magnetization of the surface monoxide layer at cryogenic temperatures. (C) 2002 Elsevier Science B.V. All rights reserved.
3.	Oberg, K., et al. (författare) Comparison of monolayer films of stearic acid and methyl stearate on an Al2O3 surface 2001 Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090. ; 397:1-2, s. 102-8 Tidskriftsartikel (refereegranskat)abstract Both stearic acid and methyl stearate chemisorbs onto an oxide surface of aluminum with an asymmetric coordination of the carboxylate group as concluded from infrared (IR) spectroscopy data. Similarities in the IR spectra of the films from the two compounds suggest that the ester is bonded in the same way as the acid, and that the ester therefore undergoes hydrolysis during the surface reaction. X-Ray photoelectron spectroscopy (XPS) and IR data are interpreted in terms of self-assembled monolayer formation and a more dense film from the carboxylic acid in comparison with that from the ester. (C) 2001 Elsevier Science B.V. All rights reserved.
4.	Selinder, T.I., et al. (författare) Structural characterization of yttria (Y2O3) inclusions in YBa2Cu3O7−x films : Growth model and effect on critical current density 1993 Ingår i: Thin Solid Films. - 0040-6090. ; 229:2, s. 237-248 Tidskriftsartikel (refereegranskat)abstract A higher critical current and enhanced pinning was obtained in c-axis-oriented YBa2Cu3O7−x (YBCO)films having a higher density of semicoherent yttria (Y2O3) inclusions. The films were grown by sputtering and the inclusion density depends on the fraction of N2O in the sputtering gas. The inclusions were studied by transmission electron microscopy, both in planar sections and in cross-sections. They are embedded in the YBCO matrix without disturbing its structure appreciably, and the inclusion density is up to about 1017 cm−3, comprising about 4% of the film volume. From the appearance of moiré fringes and from high resolution transmission electron micrographs, it is concluded that the inclusions are highly oriented and have coherent or semicoherent interfaces towards matrix. A model for formation of the yttria inclusions during film growth is presented, which includes nucleation of epitaxial coherent yttria islands, layer-by-layer growth and finally overgrowth by advancing steps of the YBCO film. The enhanced pinning and transport critical current densities, relation to film microstructure and the possible flux-pinning mechanisms by these yttria inclusions are discussed.
5.	Sjöström, H., et al. (författare) Microstructure of amorphous C:H and metal-containing C:H films deposited on steel substrates 1993 Ingår i: Thin Solid Films. - 0040-6090. ; 232:2, s. 169-179 Tidskriftsartikel (refereegranskat)abstract Cross-sectional transmission electron microscopy (XTEM), including high-resolution microscopy (HREM), was employed to characterize the interface between different amorphous hydrogenated carbon (a-C:H) films and steel substrates. Additional analyses using Auger electron spectroscopy (AES) and X-ray diffraction (XRD) were also performed. Films were deposited both by high-energy (50 keV) nitrogen ion-beam decomposition of large hydrocarbon molecules and by magnetron plasma decomposition of C2H2 in mixed Ar-C2H2 discharges. The latter method was also used to deposit Mo- or W-containing a-C:H films (Me-C:H films) onto steel substrates with interlayers of the pure metals between the substrate and Me-C:H film. The films were found to be truly amorphous except for the cases of the metal-containing films, where 1–2 nm crystalline clusters were present in an a-C:H matrix. In the case of Mo the clusters were identified from HREM micrographs to have a bcc-like structure, characteristic of metallic Mo. The metal interlayers had a columnar microstructure with column widths of ∼ 30 nm. The interfaces between the Mo and W interlayers and the a-C:H films were found to extend over 20–40 nm with a gradual crystalline-to-amorphous transition. In most of the a-C:H film-substrate interface regions a thin layer ( < 10 nm) was observed which was predominantly amorphous but contained a small fraction of crystalline grains. AES showed an increase of both O and N close to the interface. However, for the cases with Mo and W interlayers, the substrate surface contaminants were less localized, and on some parts of the substrate surface the lattice fringes of the substrate and metal interlayer phase were continuous across a sharp interface.
6.	Sjöström, H, et al. (författare) Reactive magnetron sputter deposition of CNx films on Si(001) substrates : film growth, microstructure and mechanical properties 1994 Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 246:1-2, s. 103-109 Tidskriftsartikel (refereegranskat)abstract There is currently considerable interest in producing new materials with extreme combinations of mechanical properties such as high hardnesses and moduli. One example of such a material is crystalline C3N4, which has been predicted to have a bulk modulus higher than that of diamond. In this paper we report on experiments carried out to synthesize CNx thin films. The films were grown in an unbalanced magnetron-sputtering system by reactive sputtering of C in N2 discharges. Si(001) substrates with the native oxide removed by thermal desorption and then kept at temperatures ranging from 150 to 600°C and substrate bias voltages Vs between 7.5 and -200 V were used. The films were analysed using X-ray diffraction, transmission electron microscopy (TEM). Auger electron spectroscopy, Rutherford backscattering and nano-indentation tests. Typically the films were grown at rates of 5 nm s-1 to total thicknesses of 300 nm. Owing to an extensive re-sputtering, only low negative bias voltages (-80
7.	Rönnow, Daniel, et al. (författare) Surface roughness of oxidised copper films studied by atomic force microscopy and spectroscopic light scattering 1998 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 325:1-2, s. 92-98 Tidskriftsartikel (refereegranskat)abstract The interface roughness of Cu2O films produced by thermal oxidation of Cu was studied by spectroscopic elastic light scattering and atomic force microscopy. No correlation could be found between the roughness of the two interfaces, although the amplitude and the length scale of the roughness changed in the same way with film thickness for both interfaces. Both interfaces were found to have a fractal dimension of two. A first order perturbation theory was used to analyse the light scattering data; theory and experiment are in good agreement within the limits of the theory.
8.	Abom, A.E., et al. (författare) Influence of gate metal film growth parameters on the properties of gas sensitive field-effect devices 2002 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 409:2, s. 233-242 Tidskriftsartikel (refereegranskat)abstract Thin films of Pt have been grown as gate metals on the oxide surface of gas sensitive field-effect devices. Both electron beam evaporation and dc magnetron sputtering has been used. The energy of the impinging Pt atoms, the substrate temperature and the thickness of the Pt film were used as parameters in this study. The influence of the growth parameters on the gas response has been investigated and compared with the properties of the films, studied by transmission electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The conditions during growth of the Pt film are found to have a large impact on the properties of the device. As expected, crystallinity, morphology and the metal/substrate interfacial structure are also affected by processing parameters. Three different growth processes stand out as the most promising from gas sensor considerations, namely room temperature evaporation, sputtering at high pressures and sputtering at high temperatures. The correlation between gas responses and properties of the gas sensitive layer is discussed. © 2002 Elsevier Science B.V. All rights reserved.
9.	Almer, J, et al. (författare) Microstructure, stress and mechanical properties of arc-evaporated Cr-C-N coatings 2001 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 385:1-2, s. 190-197 Tidskriftsartikel (refereegranskat)abstract The relationships between coating microstructure and properties in the Cr-C-N system have been investigated as a function of composition and post-deposition annealing. Coatings of varying compositions were grown using arc-evaporation, by varying the reactive gas flow ratio fR = f(C2H4)/f(N2) from 0 to 0.2, and were found to consist primarily of the cubic d-Cr(C,N) phase. Changes in both the unstressed lattice parameter, ao, and X-ray diffraction background intensity indicate that both the carbon concentration within the d-phase and amorphous/crystalline content increases with fR. Increasing fR also decreases the magnitude of the compressive biaxial residual stress, from approximately 6 to 1 GPa, while increasing both the inhomogeneous stress and thermal stability. The elastic modulus and hardness of as-deposited coatings were determined from nanoindentation to be 320 and 23 GPa, respectively, for moderate carbon concentrations (fR=0.05). Concurrent variations in microstructure and hardness with post-deposition annealing indicate that the as-deposited hardness is significantly enhanced by the microstructure, primarily by lattice defects and related stresses (microstresses) rather than average stresses (macrostresses).
10.	Almqvist, Nils, et al. (författare) Roughness determination of plasma-modified surface layers with atomic force microscopy 1995 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 270:1-2, s. 426-430 Tidskriftsartikel (refereegranskat)abstract Graphite surfaces exposed to the deuterium plasma in the TEXTOR tokamak were characterized in detail by means of scanning probe microscopy, ion beam analysis and colorimetry methods. The aim is to study the composition and structure of thin layer deposits formed on surfaces subjected to the tokamak plasma. The surface roughness was measured and parametrized in terms of fractal dimension and scaling constant. Several different methods for the fractal analysis of plasma-exposed surfaces have been critically evaluated. The main emphasis of this paper is on the correlation between surface roughness (fractal parameters), the amount of deposited atoms and the layer thickness.
11.	Andersson, Kent, et al. (författare) High stability titanium nitride based solar control films 1992 Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 214:2, s. 213-218 Tidskriftsartikel (refereegranskat)abstract Triple-layer structures of TiO2TiN/TiO2 and quadruple layer structures of TiO2Al/TiN/TiO2 have been sputtered on glass substrates at temperatures ranging from room temperature to 300°C. The reflectance and transmittance were measured in the visible and the near-IR wavelength regions. The thin layer of aluminium, in the quadruple layer, oxidizes and forms a dense diffusion barrier. The multilayers exhibit improved optical selectivity which also improves with substrate temperature up to 300°C.
12.	Arias, A.C., et al. (författare) Use of tin oxide thin films as a transparent electrode in PPV based light-emitting diodes 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 371:1, s. 201-206 Tidskriftsartikel (refereegranskat)abstract Tin oxide (TO) thin films, nominally undoped, have been used as electrodes in poly(p-phenylene vinylene) (PPV) based organic electroluminescent devices. The evolution of the crystallinity and the electrical resistance of TO films submitted to the PPV thermal conversion conditions, have been investigated. It has been found that the electrical resistance is decreased whereas the crystallinity of the film is increased. It is shown in this work, that the photoluminescence of PPV converted on top of TO substrates is not as quenched as it is when converted on top of indium-tin oxide (ITO) substrates. The quantum efficiency of light-emitting diode is 0.07% at 17 V forward bias. It is also shown that the work function of TO films is very stable to different cleaning procedures, in contrast with previous results obtained for ITO films.
13.	Arwin, Hans (författare) Ellipsometry on thin organic layers of biological interest : Characterization and applications 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 377-378, s. 48-56 Tidskriftsartikel (refereegranskat)abstract The thickness resolution and in situ advantage of ellipsometry make this optical technique particularly suitable for studies of thin organic layers of biological interest. Early ellipsometric studies in this area mainly provided thickness quantification, often expressed in terms of surface mass. However, today it is possible to perform monolayer spectroscopy, e.g. of a protein layer at a solid/liquid interface, and also to resolve details in the kinetics of layer formation. Furthermore, complicated microstructures, like porous silicon layers, can be modeled and protein adsorption can be monitored in such layers providing information about pore filling and penetration depths of protein molecules of different size and type. Quantification of adsorption and microstructural parameters of thin organic layers on planar surfaces and in porous layers is of high interest, especially in areas like biomaterials and surface-based biointeraction. Furthermore, by combining ellipsometric readout and biospecificity, possibilities to develop biosensor concepts are emerging. In this report we review the use of ellipsometry in various forms for studies of organic layers with special emphasis on biologically-related issues including in situ monitoring of protein adsorption on planar surfaces and in porous layers, protein monolayer spectroscopy and ellipsometric imaging for determination of thickness distributions. Included is also a discussion about recent developments of biosensor systems and possibilities for in situ monitoring of engineering of multilayer systems based on macromolecules.
14.	Bantikassegn, W., et al. (författare) Absence of Schottky barrier formation in junctions of Al and polypyrrole-polyelectrolyte polymer complexes 1993 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 224:2, s. 232-236 Tidskriftsartikel (refereegranskat)abstract Thin films of conducting polypyrrole doped with large polymeric anions of polystyrene-sulphonate are electrochemically prepared to study the metal/polymer junctions. Aluminium and gold contacts are vacuum deposited to form metal/polymer/gold sandwich structures for current-voltage characterization. Photoelectron spectroscopy, using UV and X-ray photons, is carried out to investigate the possible causes of current limitation in the Al/PPy(PSS) junction.
15.	Baudin, M., et al. (författare) Molecular dynamics simulations of an Al2O3(0001 +/-, 0-10(II))/CeO2 (011 +/-,01-1(II)) interface system 2001 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 401:02-jan, s. 159-164 Tidskriftsartikel (refereegranskat)abstract Constant stress, constant temperature (10 K, 300 K) molecular dynamics simulations were carried out with shell-model potentials for an infinite composite ceria-alumina slab with two free surfaces [alpha -Al2O3 (0001) and CeO2(011) and their opposite counterparts]. The interface introduces considerable structural and dynamical changes, both at the slab surfaces and in the center of the slab. Structurally, both oxide surfaces become effectively oxygen-terminated and the surface structures become disordered close to the interface. Dynamically, in the region near the 'alumina surface/ceria surface/alumina-ceria interface' 3-phase junction the ionic motion is considerably enhanced. Thus, in the interface region, the ionic mean-square displacements increase 2-3 times compared to the pure slabs. Moreover, the ions at the interface participate in a new kind of motion, not present in the pure oxide slabs: large occasional, but frequently reoccurring, back-and-forth ionic motions take place with square-amplitudes as large as similar to0.70 Angstrom (2).
16.	Cardona, M., et al. (författare) Ellipsometric investigations of piezo-optical effects 1998 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 313-314, s. 10-17 Tidskriftsartikel (refereegranskat)abstract An introduction to the stress-induced birefringence of solids, with emphasis on cubic and amorphous materials, is given. Most available experimental data have been obtained in the frequency region below the electronic absorption edge: the corresponding coefficients of the stress-optical tensor are then real. Above the edge (and also in the IR region of the Reststrahlen) they become complex. Ellipsometry is an excellent tool for the investigation of complex stress-optical functions. It also yields the hydrostatic pressure induced changes in the dielectric functions. Data obtained recently for diamond and zincblende-type crystals and their theoretical interpretation are discussed.
17.	Carlberg, M H, et al. (författare) Defects and energy accommodation in epitaxial sputter deposited Mo/W superlattices studied by molecular dynamics 1998 Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 317:1-2, s. 10-13 Tidskriftsartikel (refereegranskat)abstract We report here the results of a Molecular Dynamics-Embedded Atom Method-investigation of the pathways generating point defects in Mo/W superlattices during bombardment with energetic (50 to 200 eV) Ar and Kr neutrals. Energy accommodation coefficients are computed for the different structures and are found to be roughly independent of the incident energy, and substantially higher for structures with Mo on top. Several different types of defects are shown, and two general processes generating those are discussed. Trapping of the incoming noble gas was observed for the case of Kr impinging on structures with Mo as the top monolayer; this is interpreted as an effect of the small mass difference between the Mo and the Kr atoms. An increase in atomic mass of the gas translates into a more disparate behaviour of the studied structures. The energy exchange with the surface layer dictates the behaviour of the superlattice; this is accentuated when bombarding with the heavier gas, Kr. (C) 1998 Elsevier Science S.A.
18.	Chen, Weimin (författare) Applications of optically detected magnetic resonance in semiconductor layered structures 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 364:1, s. 45-52 Tidskriftsartikel (refereegranskat)abstract A short introduction is given on the physics, method, capabilities and limitations of the optically detected magnetic resonance (ODMR) technique. The advantages of the optical detection method in terms of sensitivity and of its direct probe in recombination processes, as compared with the traditional spin resonance technique, will be demonstrated. The importance of these advantages for the ODMR applications in semiconductor layered and quantum structures will be emphasized. The ability of the ODMR technique to provide important information on physical properties of semiconductor layered structures will be highlighted. These include chemical identification, electronic and geometric structure of both radiative and non-radiative defects, carrier recombination mechanism, electronic excitation, etc. Representative cases from CVD-SiC and MBE-Si/SiGe based layered structures will be discussed as examples. The most recent progress, on-going efforts and prospects in achieving unprecedentedly high spectral, time and spatial resolution of the ODMR technique will also be outlined.
19.	Chirita, Valeriu, et al. (författare) Cluster diffusion and surface morphological transitions on Pt (111) via reptation and concerted motion 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 370:1, s. 179-185 Tidskriftsartikel (refereegranskat)abstract Embedded-atom molecular dynamics simulations were used to follow the diffusion dynamics of compact Pt clusters with up to 19 atoms on Pt (111) surfaces. The results reveal a novel cluster diffusion mechanism, involving successive shear translations of adjacent subcluster regions, which give rise to reptation, a snake-like gliding motion. We show that for compact clusters with 4 to 6 atoms, this mechanism competes energetically with that of island diffusion through concerted motion. However, as the cluster size increases from > 7 to ? 20 atoms, reptation becomes the energetically favored diffusion mechanism. The concerted shear motion of subcluster regions, leading to reptation, is also shown to play a significant role in dendritic-to-compact morphological transitions of Pt island.
20.	Cobet, C., et al. (författare) Optical properties of SiC investigated by spectroscopic ellipsometry from 3.5 to 10 eV 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 364:1, s. 111-113 Tidskriftsartikel (refereegranskat)abstract In this work we present the dielectric function of hexagonal 4H- and 6H-SiC polytypes as well as the cubic 3C-SiC polytype in the energy range from 3.5 to 10 eV measured by spectroscopic ellipsometry. We operated with synchrotron radiation at the Berlin electron storage ring BESSY I. Additionally the samples were investigated by atomic force microscopy to correct the measured dielectric function for the influence of surface roughness. The experimental results are compared to theoretical calculations.
21.	Crossley, A, et al. (författare) Surface treatment for galling protection of titanium alloys : characterization by surface-specific electron and Raman spectroscopies 2002 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 414:2, s. 224-230 Tidskriftsartikel (refereegranskat)
22.	Dannetun, Per, et al. (författare) High-resolution electron energy loss spectroscopy of thin crystalline highly oriented films of poly(tetrafluoroethylene) 1996 Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 286:1-2, s. 321-329 Tidskriftsartikel (refereegranskat)abstract High-resolution electron energy loss spectroscopy (HREELS) spectra of highly oriented films of poly(tetrafluoroethylene) (PTFE) are reported. With one exception, all peaks in the spectra correspond to IR active vibrations. They are well resolved, and with a remarkably high intensity, more than two orders of magnitude greater than we have observed on any other polymer in HREELS. The angular distributions of the elastic peak, and of the vibrational peaks are very narrow, which indicates both a well ordered system and a dipolar scattering behaviour. No evidence of amorphous regions in these films is found. A Raman active mode can be observed in off-specular geometry, using an incident electron beam coplanar with the PTFE fibers direction. This corresponds to resonance excitation of a transient negative ion state, with a maximum cross-section at an incident electron kinetic energy of about 4 eV.
23.	Dilawar, Nita, et al. (författare) Adhesion enhancement of diamond coatings on WC tools by high energy ion irradiation 1998 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 323:1-2, s. 163-169 Tidskriftsartikel (refereegranskat)abstract Microcrystalline diamond thin films were deposited on cemented tungsten carbide cutting tools by hot-filament chemical vapour deposition process. The coatings deposited were irradiated with 50 MeV Si7+ ions upto a dose of <1013 ions cm-2. The adhesion and wear characteristics of as-deposited and irradiated coatings were studied and it was found that irradiation induced increased adhesion of the coatings to the substrate resulting in reduced coating failure during wear tests.
24.	Donchev, V., et al. (författare) Photoluminescence study of AlAs/GaAs superlattices containing enlarged wells 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 364:1, s. 224-227 Tidskriftsartikel (refereegranskat)abstract Photoluminescence (PL) spectra of MBE grown short-period AlAs/GaAs superlattices with one or two enlarged wells (5 and 12 nm) have been measured at 2 K. Sharp PL peaks corresponding to excitonic transitions between the lowest electron and heavy-hole states in the enlarged wells are observed. The excitonic transition energies are calculated by means of an envelope function based model, taking into account the exciton binding energies. The model incorporates a smooth potential at the interfaces, which is represented by a diffusion potential, the diffusion length being a parameter. The calculated and experimentally observed excitonic transition energies agree well if diffusion lengths of 3.5 and 4.5 monolayers are considered in the samples with and without a buffer layer, respectively. These values are consistent with the complicated nature of the growth kinetics and mechanisms of quantum heterostructures. The PL spectra reveal also complicated structures connected with the superlattice. Their qualitative discussion confirms the smooth potential model. Thus, an attempt is made to extend the analysis of complicated AlAs/GaAs heterostructures towards real interfaces, which is essential for advanced device fabrication.
25.	Dutta, Joydeep, et al. (författare) Application of pyrosol deposition process for large-area deposition of fluorine-doped tin dioxide thin films 1994 Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 239:1, s. 150-155 Tidskriftsartikel (refereegranskat)
26.	Dutta, Joydeep, et al. (författare) Variations in structural and electrical properties of magnetron-sputtered indium tin oxide films with deposition parameters 1988 Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 162:C, s. 119-127 Tidskriftsartikel (refereegranskat)
27.	Edwards, N.V., et al. (författare) Optical characterization of wide bandgap semiconductors 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 364:1, s. 98-106 Tidskriftsartikel (refereegranskat)abstract Our work primarily concerns the characterization of wide-gap III-V nitride semiconductors, nondestructively and at variable temperature, with spectroscopic ellipsometry (SE) and reflectometry in the spectral range from 1.5 to 6 eV. In the case of GaN, there are three main concerns associated with such data: (a) the quantification of the dispersion of the index of refraction with energy, (b) the removal of surface overlayers in real-time, and (c) the determination of the variation of valence bands with biaxial stress and the quantification of residual stress in thin films. The SE and reflectance capabilities provide (1) broadband spectra from 1.5 to 6 eV, which yield information about (a) below the bandgap and (b) above it, and (2) high resolution spectra (less than 1 meV at 3.4 eV) in the vicinity of the gap (3.3-3.6 eV), which enables (c). Here we will discuss issues concerning the relation of (c) to GaN material and growth parameters, though similar data for other wide bandgap materials will be discussed where relevant. Specifically, optimal heterostructure design for potential valence band engineering applications will be discussed in the context of trends in residual stress as a function of film thickness, growth temperature and substrate orientation for GaN/AlN/6H-SiC heterostructures. Standard heterostructures are mostly compressive for samples less than about 0.7 µm thick, are tensile up to about 2 µm and then abruptly become less tensile with stress values near 1 kbar thereafter. Additionally, these trends can be circumvented for moderately thick (approximately 2 µm) GaN layers (normally>2 kbar, tensile) by the introduction of a `buried interface' approach, namely, a strain mediating layer (SML) above the standard high-temperature AlN buffer layer designed to yield a range of compressive stresses from 0 to 2 kbar. The strain characteristics but also the growth rates of subsequently deposited nitride layers can be modulated by changing the growth parameters of the SML. This is achieved by in situ techniques during crystal growth without degrading the optical and structural properties of the deposited layer, as confirmed by XRD, SEM, PL, and AFM data taken on the overlying GaN layers. These results are interpreted in terms of coefficient of thermal expansion data for the layers and data concerning the planarization of GaN layers and growth behavior in non-(0001) directions.
28.	Enquist, F., et al. (författare) The fabrication of amorphous SiO2 substrates suitable for transmission electron microscopy studies of ultrathin polycrystalline films 1986 Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 145:1, s. 99-104 Tidskriftsartikel (refereegranskat)abstract A method to produce SiO2 transmission electron microscopy substrates by means of silicon micromachining is described. The substrate consists of an SiO2 window 50–200 nm thick suspended in a silicon frame. It was developed to enable the study of ultrathin porous gate metals grown on the same substrate as in the device studied. The thin film to be studied can be vapour phase deposited directly onto the substrate and then without any further manipulations inserted into the transmission electron microscope.
29.	Eriksson, Mats, 1963-, et al. (författare) Morphology changes of thin Pd films grown on SiO2: influence of adsorbates and temperature 1999 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 342:1-2, s. 297-306 Tidskriftsartikel (refereegranskat)abstract Under certain conditions morphology changes occur when thin Pd films, grown on SiO2 at room temperature, are subject to elevated temperatures. First holes in the metal are observed, followed by network formation and finally isolation of metal islands. This process is known as agglomeration. The influence of gas exposures on this restructuring process has been studied by following variations in the capacitance of the structure and by atomic force microscopy, transmission electron microscopy and ultraviolet photoelectron spectroscopy. The capacitance measurements show that carbonaceous species have an impeding influence on the rate of agglomeration and may lock the film structure in a thermodynamic non-equilibrium state. By removing these species with oxygen exposure, i.e. by forming volatile CO and CO2, a clean surface is obtained and the agglomeration process can proceed. High oxygen or hydrogen coverages also lower the rate of restructuring, compared to the case of a clean surface. For the clean Pd surface, an apparent activation energy of 0.64 eV is found for the restructuring process.
30.	Greczynski, G., et al. (författare) Polymer interfaces studied by photoelectron spectroscopy : Li on polydioctylfluorene and Alq3 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 363:1, s. 322-326 Tidskriftsartikel (refereegranskat)abstract The behavior of lithium atoms deposited on the surfaces of ultra-thin spin-coated films of poly(dioctylfluorene), and of condensed molecular solid films of tris(8-hydroxyquinoline) aluminum, have been studied through a combined experimental-theoretical approach. The Li-atoms donate charges to the organic systems, leading to doping-induced electronic states in the otherwise forbidden energy gap. The changes in the electronic structure induced by charge transfer from the Li-atoms are different in the two materials studied, and depend upon the localization of the electronic states to which the electrons are transferred. In the case of the delocalized wave functions of the p-system of poly(dioctylfluorene), at low doping levels, the added charges lead to the formation of polaron states, while at higher doping concentrations, bipolaron states are formed. In the case of the tris(8-hydroxyquinoline) aluminum, however, up to a level of three added electrons per molecule, the added electrons reside in states localized on each of the three ligands.
31.	Grivickas, V., et al. (författare) Spatially and time-resolved infrared absorption for optical and electrical characterization of indirect band gap semiconductors 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 364:02-jan, s. 181-185 Tidskriftsartikel (refereegranskat)abstract The current status of the spatially and time-resolved free-carrier absorption (FCA) method is provided. The FCA technique allows monitoring carrier dynamics in a time scale from nanoseconds to miliseconds by employing either collinear or orthogonal geometry between pump and probe beams. A high spatial resolution is achieved allowing in-depth carrier profiles to be extracted. The method is particularly suited for investigation of injection-dependent optical and recombination phenomena: band gap optical absorption, Shockley-Read-Hall (SRH) lifetime, Auger recombination coefficient, and the injection-dependent surface (interface) recombination velocity. We summarize important aspects of the technique demonstrating numerous measurements that have been implemented in studies of bulk Si, epilaxial 4H-SiC and porous silicon.
32.	Hammar, M., et al. (författare) Investigation of chemically vapour deposited tungsten and tungsten silicide as contacts to n+ and p+ silicon areas 1990 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 185:1, s. 9-19 Tidskriftsartikel (refereegranskat)abstract Tungsten and WSi2 have been examined as contact barriers between aluminium and n+ - or p+ -Si. The specific contact resistivity and diode leakage current were evaluated after heat treatment at different temperatures. Rutherford backscattering spectrometry measurements, X-ray diffraction analysis, scanning electron microscopy and sheet resistance measurements were performed to study the thermal stabilities of the Al/W/Si and Al/WSi2/Si systems. The contact resistivities of chemically vapour deposited tungsten and WSi2 to n+ -Si with a surface concentration of 7.5 × 1019 cm-3 were 8 × 10-7 Ωcm2 and 9 × 10-7 Ωcm2 respectively. To p+ -Si with a surface concentration of 2.6 × 1019 cm-3, they were 5 × 10-6 and 1 × 10-6 Ωcm2. Diffusion of aluminium was revealed to occur above 475°C in the case of tungsten and at 475°C in the case of WSi2. The void formation in silicon substrates was observed after heat treatment at 500°C for the Al/WSi2/Si system. The increase in leakage current for the Al/W/Si and Al/WSi2/Si structures is related to the onset of Si-Al interpenetration. Alloy formation was observed at 500°C for tungsten contacts whereas W-Al or other alloys were not detected up to 600°C for the WSi2 contact.
33.	Hellgren, N., et al. (författare) Effect of chemical sputtering on the growth and structural evolution of magnetron sputtered CNx thin films 2001 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 382:1-2, s. 146-152 Tidskriftsartikel (refereegranskat)abstract The growth and microstructure evolution of carbon nitride CNx (0=x=0.35) films, deposited by reactive d.c. magnetron sputtering in Ar/N2 discharges has been studied. The substrate temperature TS varied between 100 and 550 °C, and the N2 fraction in the discharge gas varied from 0 to 100%. It is found that the deposition rate and film morphology show strong dependence on TS and nitrogen fraction. For growth temperature of 100 °C, the films are amorphous, and essentially unaffected by the nitrogen fraction. For TS>200 °C, however, the nitrogen fraction has more significant effect on the growth and structural evolution of the films. The pure carbon films appear porous and have a high surface roughness. For increasing nitrogen fraction the films become denser and the roughness decreases by one order of magnitude. It is suggested that a chemical sputtering process, during which desorption of volatile N2 and CN-species, predominantly C2N2, is important not only for the deposition rate and the nitrogen incorporation, but also for the resulting film structure. The chemical sputtering process becomes more pronounced at elevated temperatures with higher nitrogen fractions.
34.	Hirschauer, B, et al. (författare) Highly oriented alpha-alumina films grown by pulsed laser deposition 1997 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 305:1-2, s. 243-247 Tidskriftsartikel (refereegranskat)abstract Highly oriented thin films of alpha-alumina have been grown by pulsed laser deposition on Si(lll). The influence of the substrate temperature on the film growth was studied by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (MID). Ablation at temperatures between room temperature and 850 degrees C gave rise to incorporated crystalline aluminium (Al), while the stoichiometric and highly oriented alpha-Al2O3 films were obtained only at 850 degrees C. The XRD rocking curve measurements of the ablated films showed the full-width-at-half-maximum (FWHM) Of 0.2 degrees. Further annealing at 1000 degrees C in air for 26 h slightly improved out-of-plane orientation. (C) 1997 Elsevier Science S.A.
35.	Hirschauer, B, et al. (författare) Studies of highly oriented CeO2 films grown on Si(111) by pulsed laser deposition 1999 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 348:1-2, s. 3-7 Tidskriftsartikel (refereegranskat)abstract CeO2 is an interesting buffer layer material for the growth of YBa(2)Cu(3)O(7-)delta overlayers on Si in devices, with the aim of preventing heat-diffusion due to its excellent lattice matching with Si and YBa(2)Cu(3)O(7-)delta. Epitaxial CeO2-films have been synthesised on Si(lll) by pulsed laser deposition. Stoichiometric changes of the CexOy-film depending on the ambient oxygen pressure during the deposition were studied by X-ray photoelectron spectroscopy. A method is presented for growing a sharp interface between CeO2 and Si(111). The dependence of the inplane orientation of the CeO2 film on the substrate temperature was investigated by X-ray diffraction. The best films, grown at 700 degrees C, showed full width at half maximum of the rocking curve close to 0.1 degrees, but already at room temperature very highly oriented films with less than 0.2 degrees were synthesised. (C) 1999 Elsevier Science S,A. All rights reserved.
36.	Hultaker, A., et al. (författare) Electrical and optical properties of sputter deposited tin doped indium oxide thin films with silver additive 2001 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 392:2, s. 305-310 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract Tin doped indium oxide (ITO) films with a few mol% of silver were prepared by reactive DC magnetron sputtering. The purpose of adding silver is to boost conductivity. The real part of the refractive index of ITO was determined from ellipsometry data, applying a model combining a Drude and a Lorentz term. The imaginary part was calculated from the absorptance, which was derived from transmittance and reflectance data. We found that up to 6 mol% of silver additive enhanced the conductivity by as much as a factor of two for layers post-treated at 200 and 300°C in reducing gas consisting of 93% N2 and 7% H2. For samples with 1 mol% silver, which was post-treated at 100 and 200°C, we observed an increase in the luminous transmittance. The transmittance decreased with increased silver content. © 2001 Elsevier Science B.V.
37.	Jin, P., et al. (författare) Epitaxial growth of W-doped VO2/V2O3 multilayer on a-Al2O3(110) by reactive magnetron sputtering 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 375:1-2, s. 128-131 Tidskriftsartikel (refereegranskat)abstract Multilayer epitaxy with a W-VO2 top layer over a bottom layer of which the crystal phase depends on the starting oxygen flow, was done on a-Al2O3(110) by reactively sputtering a V-W (1.6 at.% wt.) alloy target at linearly increasing oxygen flow without interrupting film growth. For the film deposited in the oxygen flow from 10 to 26 sccm, a W-VO2/W-V2O3 multilayer was formed on a-Al2O3(110) with the epitaxial relationship being (001)f?(110)s, (110)f?(001)s for W-V2O3, and (010)f?(110)s, (100)f?(001)s for W-VO2 where f and s denote the film and substrate, respectively. The formation of a triple domain structure was confirmed in the W-VO2 top layer due to the strong influence from the symmetry of the substrate. The multilayer shows phase transition behavior differing from the single layer film, which was presumably due to the effects of W-doping, compositional gradient, and strain.
38.	Johansson, M P, et al. (författare) Growth of CNx/BN : C multilayer films by magnetron sputtering 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 360:1-2, s. 17-23 Tidskriftsartikel (refereegranskat)abstract Symmetric CNx/BN:C multilayer thin films, with nominal compositional modulation periods of ? = 2.5, 5, and 9 nm were deposited by unbalanced dual cathode magnetron sputtering from C (graphite) and B4C targets in an Ar/N2 (60/40) discharge. The multilayers and single-layer of the constituent CNx and BN:C compounds were grown to a total thickness of 0.5 µm onto Si(001) substrates held at 225°C and a negative floating potential of approx. 30 V (Ei = 24 eV). Layer characterizations were performed by TEM, X-ray reflectivity, RBS, and nanoindentation measurements. Results show that CN0.33 and BN:C (35, 50, and 15 at.% of B, N, and C, respectively) layers were prepared at the above conditions. It is suggested that all films exhibit a three-dimensional interlocked structure with a cylindrical texture in the film growth direction. The structure was continuous over relatively well defined and smooth CNx/BN:C interfaces. All coatings exhibit extreme elasticity with elastic recoveries as high as 85-90% (10 mN maximum load) attributed to the observed structure. However, the multilayers were stiffer and more elastic compared to that of the single-layers and thus shows promise for improved protective properties.
39.	Jonsson, Lars, et al. (författare) Compositional variations of sputter deposited Ti/W barrier layers on substrates with pronounced surface topography 1999 Ingår i: THIN SOLID FILMS. - 0040-6090 .- 1879-2731. ; 348:1-2, s. 227-232 Tidskriftsartikel (refereegranskat)abstract Sputter deposited Ti/W barrier layers have been found to be Ti deficient with respect to the target composition, which is attributed to the preferential resputtering of Ti from the deposited films by energetic neutrals or ions from the discharge. On the o
40.	Kakanakova-Georgieva, Anelia, 1970-, et al. (författare) Characterization of ohmic and Schottky contacts on SiC 1999 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 343-344, s. 637-641 Tidskriftsartikel (refereegranskat)abstract The interface chemistry of nickel and tungsten based contacts on SiC has been investigated by XPS on as-deposited samples and after contact formation. After annealing at 950 °C for 10 min, Ni/SiC and Ni/Si/SiC ohmic contacts are formed due to the chemical reactions, as a result of which Ni2Si appears. However, Ni/Si (instead of pure Ni) deposition on SiC leads to modification of the diffusion processes and formation of a contact layer free of carbon. After annealing at 1200 °C for 4 min, the WN (W)/SiC systems are characterized by strong interface reactions resulting in W5Si3 and W2C formation in the contact layer. The 800 °C annealed WN/SiC contact is characterized by a chemically inert interface, and is found to be of a Schottky type.
41.	Kakanakova-Georgieva, Anelia, 1970-, et al. (författare) XPS characterization of tungsten based contact layers on 4H-SiC 1999 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 337:1-2, s. 180-183 Tidskriftsartikel (refereegranskat)abstract Annealed W (WN)/4H–SiC interfaces have been compared on the basis of X-ray photoelectron spectroscopy (XPS) studies. The 1200°C annealed W (WN)/4H–SiC structures are characterized by intense interface reactions leading to tungsten carbide and tungsten silicide formation in the contact layers. The 800°C annealed WN/4H–SiC structure exhibits a chemically inert interface, and the 800°C annealed WN/4H–SiC contact is found to be of a Schottky type with a barrier height of 0.94 eV and an ideality coefficient of 1.09.
42.	Karlsson, L., et al. (författare) Influence of residual stresses on the mechanical properties of TiCxN1-x (x = 0, 0.15, 0.45) thin films deposited by arc evaporation 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 371:1, s. 167-177 Tidskriftsartikel (refereegranskat)abstract The influence of residual stress state and composition on the mechanical properties of arc evaporated TiCxN1-x thin films been investigated. By controlling the flow ratios of the reactive gases, N2 and CH4, films with compositions x = 0 (TIN), x to approximately 0.15, and x to approximately 0.45 have been grown on cemented carbide substrates. The residual stress state was altered through variations in the negative substrate bias over the range 20 V=Vs=820 V. The intrinsic stress, sint, measured by the X-ray diffraction (XRD) sin2? method was compressive and increased with decreasing Vs and increasing x. The latter behavior is suggested to be due to increased effective stability of defect complexes when the carbon content increases. Maximum stress level was between -6 and -7 GPa and limited by interior cracking of the films. The increase in intrinsic stress was accompanied by an increase in XRD peak broadening due to inhomogeneous strains. The hardness, H, and Young's modulus, E, of as-deposited films were measured using the nanoindentation technique. Apparently linear correlations between sint and H were found for each film composition where H increased with x. The maximum H, 44 GPa, was thus obtained for the x to approximately 0.45 film with sint = -5.5 GPa. The lowest hardness for this composition was 35 GPa for a film with sint = -2.7 GPa. For the TiN films, a similar variation in hardness of 33 GPa at sint = -5.8 to 26 GPa at sint = -1.2 GPa was obtained. E was constant at approximately 610 GPa for most of the films, with a slight decrease in the films with the lowest sint values.
43.	Kullman, L., et al. (författare) Elastic Light Scattering and Electrochemical Durability of Electrochromic Tungsten-oxide-based Films 1996 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 288:1-2, s. 330-333 Tidskriftsartikel (refereegranskat)abstract Electrochromic W-oxide-based films were produced by reactive d.c. magnetron sputtering. Fluorination and substrate bias were used to modify the film properties. Spectral measurements of the total and diffuse light scattering showed that the diffuse component remained at much less than 1% in the visible, irrespective of electrochemical degradation, which is low enough for smart windows applications.
44.	Lloyd Spetz, Anita, et al. (författare) X-ray photoemission and Auger electron spectroscopy analysis of fast responding activated metal oxide silicon carbide gas sensors 1997 Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 299:1-2, s. 183-189 Tidskriftsartikel (refereegranskat)abstract Platinum-silicon dioxide-silicon carbide, MOSiC, sensors are possible to operate at high temperatures and show a gas sensitivity pattern which is of interest for many applications including exhaust gases from car engines. The introduction of a buffer layer of tantalum silicide between the metal and the silicon dioxide resulted, after an annealing step, in a very good adhesion of the gate contact and fast responding sensors with improved signal stability. Depth profiling using X-ray photoemission and Auger electron spectroscopy showed that the annealing step converts the tantalum silicide to a mixed phase predominantly containing tantalum pentoxide. Tantalum silicide as well as platinum silicide are also present in the metal-oxide interface region.
45.	Lu, J., et al. (författare) Chemical vapour deposition of molybdenum carbides : aspects of phase stability 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 370:02-jan, s. 203-212 Tidskriftsartikel (refereegranskat)abstract Thin films of different molybdenum carbides (delta-MoC1-x, gamma'-MoC1-x and Mo2C) have been deposited from a gas mixture of MoCl5/H-2/C2H4 at 800 degrees C by CVD. The H-2 content in the vapour has a strong influence on the phase composition and microstructure. Typically, high H-2 contents lead to the formation of nanocrystalline delta-MoC1-x films while coarse-grained gamma'-MoC1-x, is formed with an H-2-free gas mixture. This phase has previously only been synthesized by carburization of Mo in a CO atmosphere and it has therefore been considered as an oxycarbide phase stabilized by the presence of oxygen in the lattice. Our results, however, show that gamma'-MoC1-x films containing only trace amounts of oxygen can be deposited by CVD. Stability calculations using a FP-LMTO method confirmed that the gamma'-MoC1-x phase is stabilized by oxygen but that the difference in energy between e.g. delta-MoC0.75 and oxygen-free gamma'-MoC0.75 is Small enough to allow the synthesis of the latter phase in the absence of kinetic constraints. Annealing experiments of metastable delta-MoC1-x and gamma'-MoC1-x films showed two different reaction products suggesting that kinetic effects play an important role in the decomposition of these phases.
46.	Lu, J, et al. (författare) Chemical vapour deposition of molybdenum carbides: aspects of phase stability 2000 Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 370:1-2, s. 203-212 Tidskriftsartikel (refereegranskat)abstract Thin films of different molybdenum carbides (δ-MoC1−x, γ′-MoC1−x and Mo2C) have been deposited from a gas mixture of MoCl5/H2/C2H4 at 800°C by CVD. The H2 content in the vapour has a strong influence on the phase composition and microstructure. Typically, high H2 contents lead to the formation of nanocrystalline δ-MoC1−x films while coarse-grained γ′-MoC1−x is formed with an H2-free gas mixture. This phase has previously only been synthesized by carburization of Mo in a CO atmosphere and it has therefore been considered as an oxycarbide phase stabilized by the presence of oxygen in the lattice. Our results, however, show that γ′-MoC1−x films containing only trace amounts of oxygen can be deposited by CVD. Stability calculations using a FP-LMTO method confirmed that the γ′-MoC1−x phase is stabilized by oxygen but that the difference in energy between e.g. δ-MoC0.75 and oxygen-free γ′-MoC0.75 is small enough to allow the synthesis of the latter phase in the absence of kinetic constraints. Annealing experiments of metastable δ-MoC1−x and γ′-MoC1−x films showed two different reaction products suggesting that kinetic effects play an important role in the decomposition of these phases.
47.	Münger, Peter, et al. (författare) Destabilization and diffusion of two-dimensional close-packed Pt clusters on Pt(111) during film growth from the vapor phase 1998 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 318:1-2, s. 57-60 Tidskriftsartikel (refereegranskat)abstract Cluster migration is known to be an important process during film growth at elevated temperatures, but relatively little quantitative data is available. We have used molecular dynamics simulations to follow the dynamics of small two-dimensional Pt clusters on Pt(lll) at 1000 K. While close-packed Pt-7 heptamers are extremely stable structures, the addition of a single-cluster vacancy or an on-top adatom immediately results in intracluster bond breaking, reconfigurations, rotations, the introduction of stacking faults, and greatly enhanced cluster-diffusion rates. Mapping center-of-mass motion for total simulation times > 145 ns revealed increases in cluster velocities by more than an order of magnitude with cluster migration occurring primarily by concerted motion and a novel diffusion mechanism involving double shearing of dimers/trimers. Contrary to some previous reports, edge-atom diffusion plays only a minor role. (C) 1998 Elsevier Science S.A.
48.	Ni, Wei-Xin, et al. (författare) Light emitting SiGe/i-Si/Si : Er 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 369:1, s. 414-418 Tidskriftsartikel (refereegranskat)abstract p+-SiGe/i-Si/n-Si:Er:O/n+-Si tunneling diodes have been processed using layer structures prepared by molecular beam epitaxy (MBE). Electroluminescence has been observed at room temperature from these devices at reverse bias. The devices have been used for characterizing the optical activation of Er3+ ions in MBE Si:Er:O layers grown at different conditions. In the range of 400-575 °C, a high substrate temperature is favored for formation of Er emission centers, but this is limited by the silicidation process occurring above 600 °C. Several important device parameters such as the impact excitation cross section and various EL decay processes have been carefully studied. A fast decay (approximately 4 µs) due to the Auger carrier transfer process is observed.
49.	Niklasson, Gunnar A., et al. (författare) Surface roughness of pyrolytic tin dioxide films evaluated by different methods 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 359:2, s. 203-209 Tidskriftsartikel (refereegranskat)abstract The scaling of surface roughness in thin spray pyrolyzed fluorinated tin dioxide films of different thicknesses was obtained from atomic force microscopy. The data show that, within experimental uncertainties, the effective dimensionality of the surface is 2; hence no evidence of fractal surface roughness was found. Other methods – based upon light scattering and cyclic voltammetry – gave additional information on the surface topography. Cyclic voltammetry measurements show that the reaction sites on the surface are distributed in a fractal structure and may be identified with hillocks seen in surface reliefs.
50.	Odén, Magnus, 1965-, et al. (författare) Microstructure-property relationships in arc-evaporated Cr-N coatings 2000 Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 377-378, s. 407-412 Tidskriftsartikel (refereegranskat)abstract Chromium nitride (Cr-N) coatings have received increased attention for tribological applications due to their favorable properties including wear resistance, toughness and oxidation resistance. These properties, in turn, can be strongly influenced by the coating microstructure and residual stress resulting from deposition and subsequent processing operations. In this study these microstructure-property correlations are investigated in Cr-N coatings grown by arc-evaporation. Prominent as-deposited features include formation of metastable amounts of the cubic d-CrN phase, and high levels of compressive residual stress and defect density. During annealing up to 650 ░C the residual stress and defect density decrease substantially, accompanied by a diffusion-based d-CrN to ▀-Cr2N phase transformation and equiaxed grain formation. The effects of these microstructural modifications on the hardness, fracture and wear properties of the coatings are evaluated using a combination of nanoindentation, scratch and pin-on-disk testing. Appreciable changes in these properties are found after annealing, and are correlated to the Cr-N microstructure. As-deposited coating hardness is enhanced by high levels of lattice defect density, with both decreasing concomitantly during annealing. Scratch results show that resistance to cohesive flaking is increased by annealing, suggesting ductility increases via defect annealing and equiaxed grain formation. Finally, the wear rate under dry sliding generally increased with annealing temperature, although wear rates of all Cr-N coatings significantly outperformed TiN tested under identical conditions.

Skapa referenser, mejla, bekava och länka

Länka till träfflistan

Träfflista för sökning "L773:0040 6090 "

Avgränsa träffmängd

År