Chemical Vapor Deposition最新文献

Terbium oxide films are deposited on silicon substrates by metal-organic (MO)CVD from a vapor of Tb(thd)₃ in argon. Terbium sesquioxide (C-form) is realized in this process. Annealing of the films in air at 800 °C, followed by cooling in air, leads to the formation of Tb₄O₇. The Ar ion-etching of the annealed films causes a reduction of Tb⁴⁺ to Tb³⁺. Optical E_g is estimated, photoluminescence spectra are investigated, and refractive indexes and dielectric constants are measured for terbium oxide films before and after annealing in air.

A well-designed and assembled apparatus for producing silicon nanoparticles by CO₂ laser-driven pyrolysis of SiH₄ is shown. The effects of process parameters (chamber pressure, laser power, gas composition) on the nano-silicon characteristics (average particle size, size distribution and shape) are systematically investigated. The produced silicon nanopowders are characterized and analyzed, demonstrating the produced particles are much smaller and much more uniform in size than the commercial products and those previously reported. The impressive productivity and yield are also discussed. This research allows a better understanding of the influences of processing parameters on silicon nanopowders, shows a controllable way of producing the desired powders, and paves the way to commercialization.

CVD is used to prepare indium tin oxide (ITO)-induced polycrystalline silicon thin films with SiH₄ as the precursor. The growth of columnar polycrystalline silicon is shown. The sheet resistance (R_□) of ITO-induced Si thin films ranges from about 167.3 to 466.2 Ω/sq. Light absorption increases, as does the detected transmittance, by about 18.4% − 30.5% for wavelengths less than 500 − 700 nm.

The ability of the two fluid method (TFM) to predict the gas-solid flow phenomenon in conical spouted beds operated with high density (6050 kg m⁻³) particles simulating the nuclear fuel coating conditions is investigated. The effects of geometric and operational factors, such as conical angle and static bed height, are also assessed. The results show that TFM predicts the time-averaged bed pressure drop quite well. The qualitative variation of the particle velocity, solids volume fraction, and axial particle flux with axial height are captured by the simulations. The simulated trends observed in the investigation of the effects of static bed height and conical angle on the particle velocity, solids volume fraction, and axial particle flux agree well with those of the experimental measurements.

Thin films of anatase titanium dioxide are deposited on fluorine-doped tin oxide (FTO) glass substrates utilizing the electric field-assisted aerosol (EA)CVD reaction of titanium isopropoxide in toluene at 450 °C. The as-deposited films are characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (RS), and UV-vis spectroscopy. The photoactivity and antibacterial activity of the films are also assessed. The characterization analysis reveals that the use of an electric field affects the film microstructure, its preferential orientation, and the functional properties. XRD of the anatase films reveals that the application of electric fields causes a change in the preferential orientation of the films from (101) to (004) or (211) planes, depending on the strength of the applied field during the deposition.

The decomposition of Mo₂O₃(S₂CNEt₂) ₄ (1) and Mo₂O₃(S₂COEt)₄ (2) single-source precursors (SSPs) via aerosol-assisted (AA⁻) CVD onto glass substrates is reported. The films grown from 2 are achieved at a lower temperature than 1 (300 and 425 °C, respectively), potentially attributable to the Chugaev elimination mechanism. Raman spectroscopy (RS) and scanning electron microscopy (SEM) show the composition of the films to be variable; films that are grown from the AACVD reaction of 1 are found to be of pure MoS₂ nanoplates, whereas those grown from 2 consist of MoO₃ microparticles and MoO₂ noncrystalline films, together with various nanostructures of MoS₂, depending on deposition temperature. The decomposition processes of the SSPs are assessed to determine why these variations in thin films are seen.