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Chemical Vapour Deposition (chemical + vapour_deposition)
Kinds of Chemical Vapour Deposition Selected AbstractsNanocrystalline non-planar carbons: Growth of carbon nanotubes and curled nanostructuresCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10-11 2005S. Orlanducci Abstract We present a variety of non-planar graphitic nanostructures selectively generated in a modified Hot-Filament Chemical Vapour Deposition (HF-CVD) apparatus, using purpose-synthesized amorphous carbon nanoparticles or graphite powders as solid state precursor. The employed methodologies enable to successfully synthesize homogeneous and well organized deposits of single- and multi-walled carbon nanotubes, onion-like nanostructures, and nanotube bundles coated by nano-sized diamond grains. Variations in the morphological aspect of such non-planar graphite-based nanostructures are observed changing the experimental conditions: the solid state reactants, the filament and substrate temperatures, the catalyst concentration, and the atomic hydrogen flux over the substrate play key roles in the phenomenon. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Morphological, structural and optical study of quasi-1D SnO2 nanowires and nanobeltsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10-11 2005D. Calestani Abstract 0.1,0.3 mm thick entanglements of quasi-one-dimensional semiconducting Tin dioxide nanocrystals, in form of nanowires and nanobelts, are successfully grown by low cost Chemical Vapour Deposition directly on large area (100 mm2) Al2O3, SiO2 and Si substrates. Their lateral size ranges from 50 to 700 nm and their length can achieve several hundreds of micrometers. Transmission Electron Microscopy reveals either the nanowires and the nanobelts grow in the tetragonal Rutile structure. Diffraction contrast analyses and selected area diffraction investigations show the nanowires are single crystals without defects while the nanobelts sometimes present twins inside. An almost cylindrical shape and an average diameter of about 30,50 nm for the smallest nanowires is reported. X-ray diffraction investigations exclude the presence of spurious phases. A broad band structured in two emissions peaked at about 450 nm and 560 nm is revealed by large area Cathotoluminescence, while single nanocrystal spectroscopy shows that the reduction of the lateral dimension of the nanobelts from 1000 nm to 50 nm blue-shifts the main emission band at 560 nm of about 40 nm (at room temperature). These preliminary results suggest a possible role of oxygen vacancies and of the surface/volume ratio on the origin and the blue shift of Cathodoluminescence spectra. The near band edge emission, typical of bulk tin dioxide (,320 nm), is not found in nanobelts narrower than 1000 nm. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nb-Doped VO2 Thin Films Prepared by Aerosol-Assisted Chemical Vapour DepositionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2007Clara Piccirillo Abstract Niobium-doped vanadium dioxide (VxNb1,xO2, x = 0,0.037) thin films were prepared by aerosol-assisted chemical vapour deposition (AACVD) of vanadyl(IV) acetonate and niobium(V) ethoxide in ethanol. Samples were analysed by EDX, XRD, Raman, XPS and SEM. The analyses confirmed the deposition of niobium, even if no separated phase was formed; the morphological structure of the films was affected by the dopant presence. The thin films showed thermochromic behaviour, with a marked change in optical properties above and below the switching temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Si/SiO2 nanocomposite by CVD infiltration of porous SiO2PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2005G. Amato Abstract The aim of the present paper is to report first results on an innovative method for producing Si/SiO2 nanocomposites. Starting from a porous oxide structure, we infiltrated Si by Chemical Vapour Deposition of SiH4, under controlled conditions. In this way, we succeeded in infiltrating Si into the SiO2 template. Porous oxide is obtained by dry oxidation of mesoporous Si. By means of the electrochemical process used for producing porous Si, an interconnected pore structure is obtained. This allows for Si infiltration, giving rise, in principle, to an interconnected network of Si crystallites, in which electrical carriers are easily driven. Efficient charge injection in Si nanocrystals is of crucial importance for several applications, from electroluminescence to memory devices. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Analysis of traps in CVD diamond films through thermal depumping of nuclear detectorsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2004A. Balducci Abstract Carrier free paths in Chemical Vapour Deposition (CVD) diamond films depend on the presence of traps, which therefore strongly affect the performance of those CVD diamond based devices which rely on the electronic properties of the material, like radiation detectors. For the same reason, these devices can in turn be used as tools to study carrier dynamics. It is well known that some traps may be saturated by pre-irradiation with ionizing radiation (e.g. ,-particles), a process called "pumping" or "priming". Not all traps behave in the same way. Due to the large bandgap of diamond, both shallow (not affected by pumping) and deep traps for electrons and holes may exist. We measured, using 5.5 MeV 241Am ,-particles, the response of high quality CVD diamond based detectors after successive annealing steps performed at selected temperatures. The analisys of the decay of the detector efficency with annealing time at several temperatures allows a quantitative evaluation of the activation energy of these defects. Two main trapping centres connected to the pumping process were found, both related to holes, having activation energies of about 1.6 eV and 1.3 eV respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photoluminescence microscopy of as-grown individual single-walled carbon nanotubes on Si/SiO2 substratesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2006Oliver Kiowski Abstract We present far-field photoluminescence (PL) imaging at room temperature of tens of micrometer long individual single-walled carbon nanotubes (SWNTs) grown and measured directly on a Si/SiO2 surface. The SWNTs are grown by Chemical Vapour Deposition (CVD) with ethanol as carbon source and contact the surface with their full length. We detect the PL and its variations along SWNTs in a home-built laser microscope with a spatial resolution of ,400 nm. We are able to reliably assign (n, m)-structure of SWNTs by measuring PL spectra in the range of 800,1600 nm as function of the excitation wavelength varying between 710 and 860 nm. This allows us to check structural integrity (changes of helicity) along the tube. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Low-cost growth of AlN using vectored-flow epitaxy for the purpose of water sterilisation in a rural environmentPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2008Matthew Branch Abstract The high V/III ratio required for the Metalorganic Chemical Vapour Deposition (MOCVD) growth of AlN using the precursors trimethylaluminium and ammonia have contributed to the excessive costs of producing ultra violet light emitting diodes (UVLEDs) which can be used in water purification. This paper introduces a novel growth technique, vectored-flow epitaxy (VFE), which maintains the separation between gaseous reagents within the growth chamber. In addition, the VFE technique, which employs atmospheric pressure growth, also pre cracks the ammonia prior to injection and thereby significantly reduces the high V/III ratio required for the growth of this material. The pre cracked ammonia also removes the need for high growth temperatures, which is known to be necessary for its thermal decomposition. With this technique, 2 ,m/h growth is possible at a V/III ratio of 50. These advances will contribute to the development of a cost-effective solution to the treatment of drinking water in a rural environment. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation of graded index SiOxNy antireflection coating for silicon solar cell manufacturingPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2007M. Lipi Abstract An optimization of SiOxNy anti-reflective coatings with graded index layers for silicon solar cells based on the Bruggeman's effective medium approximation is presented. For simulation of reflectance and absorption of graded layer, the experimental optical data of silicon nitride SiNx:H and oxynitride SiOxNy obtained by Low Frequency (440 kHz) Plasma Enhanced Chemical Vapour Deposition (LF-PECVD) were used. We have shown that the graded index oxynitride antireflection coating can reduce the effective reflectance to about 2.5% but the high absorption due to high extinction coefficient compensates this improvement and reduces the short circuit current (Jsc) of the solar cell. The improvement in the Jsc can be obtained for graded SiNxOy layer with smaller value of refractive index of SiNx (n = 2.2). In this case the graded SiOxNy layer is characterized by an abrupt concentration profile and can be considered as a double antireflection coating SiO2/SiNx. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical effect of diamond-like carbon film coating of long-period optical fiber gratingsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2007M. Smietana Abstract The paper presents diamond-like carbon (DLC) film as a coating for long-period grating (LPG) optical fiber structure. The spectral response of a DLC-coated LPG structure is strictly dependent on Radio Frequency Plasma Chemical Vapour Deposition (RF PCVD) process parameters. The paper discusses the influence of DLC deposition time and self-bias voltage to shift of the LPG resonance peak and explores the possibility of using the structure as a refractometric sensor. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Studies of the Plasma Related Oxygen Contamination of Gallium Nitride Grown by Remote Plasma Enhanced Chemical Vapour DepositionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003K.S.A. Butcher Abstract Nitrogen and ammonia plasma containment tubes of quartz and fused alumina (Al2O3) are evaluated in terms of the oxygen contamination contributed during gallium nitride film growth by RPE-CVD. In-situ gas and plasma monitoring, and material characterisation (UV,Vis transmission measurements, X-ray diffraction and SIMS) were used to determine the contaminant chemistries for the plasmas maintained in these containment tubes. Oxygen contamination using a quartz tube is shown to be unavoidable. Al2O3 based tubes used with an ammonia plasma also supply unacceptably high levels of oxygen for GaN growth. However, we show that alumina containment tubes may be conditioned in a nitrogen plasma, so that an aluminium nitride protective layer limits the oxygen contamination. [source] Optical and Structural Analysis of GaN Grown by Remote Plasma Enhanced Laser Induced Chemical Vapour DepositionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003Afifuddin Abstract High quality polycrystalline gallium nitride (GaN) films have been grown by remote plasma enhanced laser induced chemical vapour deposition (RPE-LICVD) on sapphire, silicon, and quartz substrates at temperatures below 600 °C. Transmission spectra of the films indicate excellent properties with band gap 3.38 ± 0.02 eV. A yellow band-to-band transition at 2.2 eV is observed. X-ray diffraction patterns reveal the (0002) wurtzite reflection at 2, = 34.6° is dominant. Raman spectra of the films are discussed with respect to the phonon frequencies and strain-related phenomena. Compositional analysis with heavy ion Elastic Recoil Detection shows stoichiometric nitrogen to gallium ratios and relatively small amounts of incorporated oxygen. [source] Nb-Doped VO2 Thin Films Prepared by Aerosol-Assisted Chemical Vapour DepositionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2007Clara Piccirillo Abstract Niobium-doped vanadium dioxide (VxNb1,xO2, x = 0,0.037) thin films were prepared by aerosol-assisted chemical vapour deposition (AACVD) of vanadyl(IV) acetonate and niobium(V) ethoxide in ethanol. Samples were analysed by EDX, XRD, Raman, XPS and SEM. The analyses confirmed the deposition of niobium, even if no separated phase was formed; the morphological structure of the films was affected by the dopant presence. The thin films showed thermochromic behaviour, with a marked change in optical properties above and below the switching temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Tungsten Oxide and Tungsten Oxide-Titania Thin Films Prepared by Aerosol-Assisted Deposition , Use of Preformed Solid NanoparticlesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2007Uzma Qureshi Abstract Aerosol-assisted deposition (AAD) was used to deposit films of WO3 from a suspension of solid nanoparticulate WO3 in toluene. Titania films were deposited by the aerosol-assisted chemical vapour deposition of [Ti(OiPr)4] in the presence of WO3 nanoparticles. The WO3 and TiO2 films exhibited photoactivity and photoinduced superhydrophilicity, further the titania films showed very unusual highly crenulated microstructures. These microstructures could not be obtained by sol-gel, atmospheric pressure chemical vapour deposition or evaporation routes. Furthermore, the microstructures could not be obtained from [Ti(OiPr)4] in the absence of nanoparticulate WO3. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Diamond plates on dome-like particles: preparation, characterization and field emission propertiesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2010Rajanish N. Tiwari Thin diamond microplates have been grown on dome-like/hemispherical carbon particles on titanium carbide by a microwave plasma chemical vapour deposition (MPCVD) method using a gas mixture of methane and hydrogen. The diamond microplates have a thickness of about 200,nm. A thin (300,nm) film of titanium carbide was formed during carburization of sputtered titanium on an Si(100) substrate in MPCVD. The hemispherical carbon particles were covered with diamond microplates. The diamond microplates are isolated electron-emitting spherules and exhibit a low threshold (50,V,µm,1) and high current density (0.92,mA,cm,2) in their field emission properties. A possible mechanism for the formation of the diamond microplates and hemispherical carbon particles is presented. [source] Structure of PbTe(SiO2)/SiO2 multilayers deposited on Si(111)JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2010Guinther Kellermann The structure of thin films composed of a multilayer of PbTe nanocrystals embedded in SiO2, named as PbTe(SiO2), between homogeneous layers of amorphous SiO2 deposited on a single-crystal Si(111) substrate was studied by grazing-incidence small-angle X-ray scattering (GISAXS) as a function of PbTe content. PbTe(SiO2)/SiO2 multilayers were produced by alternately applying plasma-enhanced chemical vapour deposition and pulsed laser deposition techniques. From the analysis of the experimental GISAXS patterns, the average radius and radius dispersion of PbTe nanocrystals were determined. With increasing deposition dose the size of the PbTe nanocrystals progressively increases while their number density decreases. Analysis of the GISAXS intensity profiles along the normal to the sample surface allowed the determination of the period parameter of the layers and a structure parameter that characterizes the disorder in the distances between PbTe layers. [source] UV Laser-Induced Gas-Phase Copolymerization of Carbon Disulfide and EtheneMACROMOLECULAR RAPID COMMUNICATIONS, Issue 4 2004Radmila Tomovska Abstract Summary: The laser irradiation at 193 nm of a gaseous mixture of carbon disulfide and ethene induces the copolymerization of both compounds and affords the chemical vapour deposition of a C/S/H polymer, the composition of which indicates the reaction between two to three CS2 molecules and one C2H4 molecule. Polymer structure is interpreted on the basis of X-ray photoelectron and FT-IR spectra as consisting of >CS, >CC<, CH2CH2, (CC)SnC4,,,n, C(CS)S, S(CS)S, and CSSC configurations. The gas-phase copolymerization of carbon disulfide and ethene represents the first example of such a reaction between carbon disulfide and a common monomer. Scheme showing the expected reaction of excited CS2 molecules with other CS2 molecules to form dimers, which then react with another CS2 molecule or add to ethene. [source] Transluzente oxidfaserverstärkte Glasmatrix-VerbundwerkstoffeMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 7 2003P. Fehling glass composites; fiber coating; atomic force microscopy; chemical vapour deposition Abstract Das Ziel der Untersuchungen ist die Entwicklung von transparenten Glasmatrix-Kompositen. Neben den mechanischen müssen dazu auch die optischen Eigenschaften der Komponenten aneinander angepaßt werden. Der Einfluß unterschiedlicher Faserbeschichtungen (Bornitrid-, Titandioxid-Einzelbeschichtung oder Bornitrid/Titandioxid-Doppelbeschichtung) auf die mechanischen und optischen Eigenschaften von Nextel 440-Faser verstärktem Glas wird untersucht. Mikromechanische Untersuchungen (push-in Tests) und 3-Punktbiegeversuche erbrachten die größte Verbesserung der Bruchzähigkeit für die Verbunde mit Bornitrid/Titandioxid-doppelbeschichteten Fasern. Die Verbunde mit Bornitrid bzw. Titandioxid Einzelschichten wurden durch Transmissionsmessungen im sichtbaren Spektralbereich charakterisiert. Translucent oxide fiber reinforced glasmatrix composites The aim of the work is the developement of transparent glass matrix composites. Therefore besides the mechanical properties also the optical properties of the components have to be adapted. In this study the influence of different fiber coatings (boron nitride, titanium oxide and a boron nitride/titanium oxide double coating) on the mechanical and optical properties of Nextel 440-fiber reinforced glass was investigated. Micromechanical investigations (push-in-tests) and 3-point-bending tests have shown the best improvement of the fracture toughness for the binary boron nitride/titanium oxide coating. For single coatings of boron nitride or titanium oxide the transparency was characterized by the transmission spectra. [source] Position-sensitive radiation detectors made of single crystal CVD diamondPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2009M. Pomorski Abstract Based on a single crystal chemical vapour deposition (scCVD) diamond plate a position sensitive detector [position sensitive detection position sensitive detector (PSD)] has been fabricated. The ,9,mm2 sensing area of the detector consists of a diamond-like carbon (DLC) thin film, in the form of a plane-pad resistive electrode layer deposited on the scCVD surface. The 1D position information is obtained from the resistive charge division between two collecting electrodes located at the extremities of the DLC sensing electrode. The detector properties have been tested using a 241Am ,-particles source. The timing characteristics of the device were probed using broad-band (BB) electronics: the signal formation does not exceed 30,ns, thus detector operation with a negligible ballistic effect is possible at high rates approaching 107,particles/s. The linearity and position resolution of the device was measured using low-noise charge-sensitive (CS) electronics: the position resolution reaches 30,µm (,), the deviation from linearity remain below 2% in the full range of the detector sensing area. [source] Structural and photoluminescence studies of erbium-implanted nanocrystalline silicon thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2009M. F. Cerqueira Abstract Hydrogenated amorphous and nanocrystalline silicon thin films deposited by hot wire (HW) and radio-frequency plasma-enhanced chemical vapour deposition (RF-PECVD) were erbium-implanted. Their pre-implantation structural properties and post-implantation optical properties were studied and correlated. After 1,h annealing at 150,°C in nitrogen atmosphere only amorphous films showed photoluminescence (PL) activity at 1.54,µm, measured at 5,K. After further annealing at 300,°C for 1,h, all the samples exhibited a sharp PL peak positioned at 1.54,µm, with an FWHM of ,5,nm. Amorphous films deposited by HW originated a stronger PL peak than corresponding films deposited by RF, while in nanocrystalline films PL emission was much stronger in samples deposited by RF than by HW. There was no noticeable difference in Er3+ PL activity between films implanted with 1,×,1014 and 5,×,1015,atoms,cm,2 Er doses. [source] Combined structural and optical studies of stacking faults in 4H-SiC layers grown by chemical vapour depositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2009Maya Marinova Abstract The formation of in-grown stacking faults (SFs) in chemical vapour deposition (CVD) grown 4H-SiC epilayer has been studied by high-resolution transmission electron microscopy (HRTEM) and low-temperature photoluminescence (LTPL). Local inhomogeneities in the SF density have been found, where different SF arrangements appear. They range from pure 8H-SiC unit cells to a few distinguished sequences, forming in some cases long-range semi-periodic incommensurate structures. Despite such large dispersion, the same optical (LTPL) signature is always found. This is discussed in the light of coupled quantum well models. HRTEM image showing the formation of an extended defect (16 bilayers thick) in a CVD grown 4H-SiC epitaxial layer. [source] High resolution Laplace deep level transient spectroscopy of p-type polycrystalline diamondPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2008N. Mitromara Abstract High resolution Laplace deep level transient spectroscopy (LDLTS) has been used to characterise deep electronic states in the band gap of polycrystalline p-type diamond. The thin diamond films were grown by the hot-filament chemical vapour deposition (HFCVD) technique on p-type and n-type Si for the formation of the Schottky and p,n diodes respectively. The B concentration in the diamond films ranged from 7 × 1018 cm,3 to 7 × 1021 cm,3. Conventional capacitance DLTS showed a fairly narrow peak at about 180 K from the diamond grown on p-type Si, but further analysis with LDLTS shows that this peak originates from a complex defect with up to three hole emission rates. In the case of the Schottky diode, these emission rates do not vary much with temperature which indicates that they may be due to the presence of an extended defect, where the valence band itself is changing its profile as the traps capture more carriers. LDLTS of a similar trap in the diamond grown on n-type Si also shows three emission rates, which do not vary as expected with temperature. The results are discussed in terms of defects existing in the strain fields of grain boundaries, and exhibiting non point-defect like properties. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Structural defects in homoepitaxial diamond layers grown on off-axis Ib HPHT substratesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2006T. Bauer Abstract In the present study homoepitaxial diamond films have been grown by microwave plasma chemical vapour deposition (MWPCVD) on (001)-oriented Ib HPHT substrates with off-axis angles of up to 11°. Freestanding films of several hundred microns thickness were produced by removal of the Ib substrate and of the polycrystalline rim. In high resolution X-ray diffraction (HRXRD) rocking curve measurements the crystals showed a full width at half maximum (FWHM) between (2 × 10,3)°, which is close to the instrumental limit of our setup, and maximum values of (3 × 10,2)°. The structural quality is directly reflected in the strength of the birefringence observed in the optical microscope. While the high quality sample showed a weak birefringence with a couple of localized centres distributed over the whole sample surface, a tatami-like pattern is measured for the sample with the broad rocking curve. Identical defect structures with perfect correspondence are observed in X-ray topography images. Furthermore the X-ray topographs allow to identify isolated dislocation lines. Both characterisation methods show that the defect lines are aligned along the off-axis direction which allows conclusions on the mechanism of formation. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Mg-doped AlGaN grown on an AlN/sapphire template by metalorganic chemical vapour depositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2006Hongbo Yu Abstract The growth of high-performance Mg-doped p-type AlxGa1,xN (x = 0.35) layers using low-pressure metalorganic chemical vapour deposition on an AlN/sapphire template is reported. The influence of growth conditions on the p-type conductivity of the AlxGa1,xN (x = 0.35) alloy was investigated. It was found that the p-type resistivity of the AlGaN alloy demonstrates a marked dependence on the Mg concentration, V/III ratio and group III element flow rate. A minimum p-type resistivity of 3.5 , cm for AlxGa1,xN (x = 0.35) epilayers was achieved. A Ni/Au (10 nm/100 nm) ohmic contact was also fabricated and a specific contact resistivity of 8.1 × 10,2 , cm2 was measured. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] FMR study of strain-induced magnetic anisotropies in CrO2 thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 15 2004B. Z. Rameev Abstract Epitaxial CrO2 thin films were grown on TiO2 (100) single-crystalline substrates by chemical vapour deposition (CVD) process with use of CrO3 solid precursor. The films with different thickness (27,530 nm) were studied by Ferromagnetic Resonance (FMR) technique. Strong dependence of FMR signal on the film thickness was observed in the series of CrO2 films deposited onto the pre-etched TiO2 substrates. It is shown that the magnetic behaviour of the CrO2 films arises from competition between magnetocrystalline and strain anisotropies that favour the [001] and [010] magnetization directions, respectively. For the thinnest film the strain anisotropy dominates, and the magnetic easy axis switches from [001] to the [010] direction. On the contrary, the CrO2 film grown on the unetched substrate demonstrates essentially strain-free magnetic anisotropy behaviour. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Kinetics of the heteroepitaxial growth of Ge layer at low temperature on Si(001) in UHV-CVDPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2004M. Halbwax Abstract The Ge growth at 330 °C by ultrahigh vacuum chemical vapour deposition is investigated in real time by reflection high energy electron diffraction (RHEED) in combination with atomic force microscopy and Rutherford back scattering spectrometry (RBS). The Stranski-Krastanov-related 2D to 3D transition is avoided at low temperature and the major part of the relaxation process occurs during the deposition of the first two monolayers. The very low growth rate observed during this first step is related to the deposition of Ge on Si. Beyond 2 deposited MLs, the growth rate increases drastically due to a complete coverage of Si by Ge. Finally, the deposition of Ge at 330 °C results in an in-plane lattice parameter approaching 90% of that of Ge bulk and a flat surface with rms roughness of 0.6 nm for a film thickness lower than 30 nm. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Carbon nanotubes for interconnects in VLSI integrated circuitsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2008J. Robertson Abstract The paper reviews the requirements for carbon nanotubes to be used as interconnects in VLSI integrated circuits. It describes the production by chemical vapour deposition of high density arrays of nanotubes suitable for use as interconnects, and describes their characterisation by Raman and transmission electron microscopy. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Feature Article: Bound exciton and donor,acceptor pair recombinations in ZnOPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2004B. K. Meyer The article [1] features the current state of knowledge on the optical properties of excitonic and donor,acceptor pair recombination in bulk n-ZnO, as revealed by recent photo- and cathodoluminescence measurements. The cover picture is a photograph showing an unusual look at the green luminescence of rod-shaped ZnO crystals under ultraviolet excitation. The first author, Bruno K. Meyer, is professor of physics at the Justus Liebig University of Giessen. His scientific interests include synthesis of semiconductor oxides by chemical vapour deposition and magnetron sputtering, in particular with respect to doping issues, materials science of electro- and thermochromic materials, recombination phenomena and defect characterization by magnetic resonance. This issue also contains an Editor's Choice on "Evolution of molecular ordering and phase transitions in C60/C70 solid solutions" by Gabriela Rueda-Morales and Jaime Ortiz-López [2]. [source] Polycrystalline silicon thin films on glass obtained by nickel-induced crystallization of amorphous siliconPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010J. A. Schmidt Abstract In this work, we use the nickel-induced crystallization process to crystallize a-Si:H thin films at temperatures compatible with the utilization of glass substrates. Hydrogenated amorphous silicon films are deposited on planar float glass (Schott AF37) by plasma-enhanced chemical vapour deposition. The films, between 400 and 1400 nm thick, are grown intrinsic, slightly p-doped (p - ) or with a combined structure of heavily p-doped / slightly p-doped (p+/p - ) layers. On these films we sputter nickel with concentrations between 2.5×1014 and 3×1015 at./cm2, and then we anneal the samples in a standard nitrogen-purged tube furnace. The process evolves through the formation of the nickel silicide NiSi2, which has a lattice constant very similar to that of c-Si and acts as a nucleation centre. As a result of this thermal treatment we obtain thin polycrystalline films with a grain size over 100 ,m. The high crystallinity of the samples is confirmed through optical and electron microscopy observations, X-rays diffraction and Raman spectroscopy. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Study on the excimer laser annealed amorphous hydrogenated silicon carbon films deposited by PECVDPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010G. Ambrosone Abstract Hydrogenated amorphous silicon carbon films of different carbon content were deposited by plasma enhanced chemical vapour deposition at low substrate temperature (200 °C) and were subjected to excimer laser annealing. X-ray diffraction spectra and field emission scanning electron microscopy images demonstrate that carbon content plays an important role in facilitating the crystallization process induced by the excimer laser treatment (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanocrystallites formation in a-SiC by low power plasma enhanced chemical vapour depositionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010Ayana Bhaduri Abstract Formation of nanocrystallites in the amorphous silicon carbide thin films deposited from silane methane mixture diluted in argon by plasma enhanced CVD has been studied under different levels of rf power density and Ar dilution. Systematic transformations between different polymorphic phases of SiC have been observed with changes in rf power and Ar dilution. At low Ar dilution no H-SiC (,-SiC) nanocrystallites was observed. Only traces of ,-SiC of Si were observed. With increase in Ar dilution formation of ,-SiC nanocrystallites was observed. Increase of rf power density at this dilution enhanced ,-SiC nanocrystallites but reduced ,-SiC slightly. Variation of SiC peak in the infra red absorption corresponds closely with the changes in ,-SiC nanocrystallites in the layers. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||