Search results for "amorphous"
showing 10 items of 790 documents
Changes in Amorphous Hydrogenated Carbon Films by Ultraviolet and Infrared Laser Irradiation
2013
Amorphous hydrogenated carbon lms were formed on the Si (100) wafers by a direct-ion beam deposition method from pure acetylene and acetylene hydrogen gas mixtures. The lms were irradiated with a nanosecond Nd:YAG laser working at the rst harmonics (λ1 = 1064 nm), the fourth harmonics (λ4 = 266 nm) or with a Nd:YVO4 laser working at the third harmonic (λ3 = 355 nm). The lms were studied by the Raman scattering, micro-Fourier transform infrared and Fourier transform infrared spectroscopies, null-ellipsometry, optical and scanning electron microscope, and Vickers hardness method. Irradiation by the wavelength λ1 = 1064 nm leads to graphitization and formation of the silicon carbide, because o…
Surface morphology and grain analysis of successively industrially grown amorphous hydrogenated carbon films (a-C:H) on silicon
2015
Abstract Silicon (1 0 0) has been gradually covered by amorphous hydrogenated carbon (a-C:H) films via an industrial process. Two types of these diamond-like carbon (DLC) coatings, one more flexible (f-DLC) and one more robust (r-DLC), have been investigated. Both types have been grown by a radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique with acetylene plasma. Surface morphologies have been studied in detail by atomic force microscopy (AFM) and Raman spectroscopy has been used to investigate the DLC structure. Both types appeared to have very similar morphology and sp 2 carbon arrangement. The average height and area for single grains have been analyzed for al…
Spinel-mullite composites with optical properties
1997
The aim of this paper was to study the synthesis and characterization of spinel-containing mullite based materials, using sol-gel techniques. Several gels were prepared, with nominal compositions 3(Al2−2xMx TixO3)·2SiO2 and 3(Al2−xMxO3)·2SiO2, with M=Ni+2 or Co+2 and 0.0≤x≤0.2, by hydrolysis and condensation of mixtures of aluminum, silicon and titanium alkoxides and nickel chloride. Dried gels were homogeneous and displayed a glass transition at around 750°C, which indicated that the system could be described as an amorphous silicoaluminate network.
Confocal spectromicroscopy of amorphous and nanocrystalline tungsten oxide films
2007
A Raman confocal spectromicroscopic system was used to study in situ phase composition and surface morphology in amorphous and nanocrystalline tungsten oxide and tungstate thin films, prepared on silicon and glass substrates by dc magnetron co-sputtering technique. The possible use of these films for the phase-change optical recording was demonstrated using 442 nm He–Cd laser with a variable power of up to 50 mW. The formation of nanocrystalline tungsten trioxide or tungstate phases was observed under the laser irradiation. These nanocrystalline phases show relatively strong Raman activity, which can be used for information reading purposes. A multilayer structure composed of several tungst…
Frenkel defect process in amorphous silica
2011
Point defects strongly influence optical properties of synthetic amorphous silica (synthetic a-SiO2) used in excimer laser photolithography and their properties are intensively studied. Decomposition of an Si-O-Si bond into a pair of oxygen vacancy and interstitial oxygen species is an intrinsic defect process in a-SiO2. It is similar to the creation of vacancy-interstitial pairs in crystalline materials and is regarded as "Frenkel defect process" in an amorphous material. Oxygens are also known to be emitted from a-SiO2 surfaces under irradiation with vacuumultraviolet (VUV) light or electron beam. However, the anion part of the Frenkel pair in a-SiO2, interstitial oxygen atom, lacks relia…
Memory effects in MOS capacitors with silicon rich oxide insulators
2000
ABSTRACTTo form crystalline Si dots embedded in SiO2, we have deposited thin films of silicon rich oxide (SRO) by plasma-enhanced chemical vapor deposition of SiH4 and O2. Then the materials wereannealed in N2 ambient at temperatures between 950 and 1100 °C. Under such processing, the supersaturation of Si in the amorphous SRO film produces the formation of crystalline Si dots embedded in SiO2. The narrow dot size distributions, analyzed by transmission electron microscopy, are characterized by average grain radii and standard deviations down to about 1 nm. The memory function of such structures has been investigated in metal-oxidesemiconductor (MOS) capacitors with a SRO film sandwiched be…
Potential of amorphous Mo–Si–N films for nanoelectronic applications
2003
The properties of amorphous metallic molybdenum–silicon–nitrogen (Mo–Si–N) films were characterised for use in nanoelectronic applications. The films were deposited by co-sputtering of molybdenum and silicon targets in a gas mixture of argon and nitrogen. The atomic composition, microstructure and surface roughness were studied by RBS, TEM and AFM analyses, respectively. The electrical properties were investigated in the temperature range 80 mK to 300 K. No transition into a superconductive state was observed. Nanoscale wires were fabricated using electron beam lithography with their properties measured as a function of temperature.
The Antimicrobial Action of Silver Halides in Calcium Phosphate
2014
Silver halides represent a yet unexplored avenue for imparting antimicrobial activity to calcium phosphates. Negtively charged silver halide colloids (AgI, AgBr and AgCl) were added to synthesized amorphous calcium phosphate. Concurrent melting of silver halides and crystallization to carbonated apatite at 700 oC increased the silver halide surface area available to bacteria and formed a lower solubility apatite. The effect of the matrix solubility on antimicrobial response could then be investigated. Pseudomonas aeruginosa was more sensitive to silver iodide and silver bromide than Staphylococcus aureus. Silver iodide demonstrated greater activity than silver bromide. Silver chloride did n…
Relevant factors for the eco-design of polylactide/sisal biocomposites to control biodegradation in soil in an end-of-life scenario
2017
[EN] The eco-design considers the factors to prepare biocomposites under an end-of-life scenario. PLA/sisal biocomposites were obtained from amorphous polylactide and sisal loadings of 10, 20 and 30 wt% with and without coupling agent, and subjected to biodegradation in soil according to standard IS0846. Mass loss, differential scanning calorimetry and size-exclusion chromatography were used for monitoring biodegradation. A statistical factorial analysis based on the molar mass M-n, and crystallinity degree X-c pointed out the relevance and interaction of amount of fibre and use of coupling agent with the time of burial in soil., During the preparation of biocomposites, chain scission provo…
Investigations of As-S-Se thin films for use as inorganic photoresist for digital image-matrix holography
2011
AbstractAs-S-Se chalcogenide thin films are successfully employed in classical and dot-matrix holography as inorganic photoresists for obtaining a relief-phase hologram. However using these films for image-matrix hologram recording has not been studied due to some features of image-matrix technology. For the applied research of the optical properties of As-S-Se films an experimental device of digital image-matrix holographic recording based on 100 mW 405 nm semi-conductor laser and Spatial Light Modulator (SLM) has been created. The device has the following main parameters: 140 × 105 µm frame size; laser intensity during exposure 10 W/cm2. With the help of this device diffraction grating an…