A probabilistic and diffusion-based model describing concentrations of multiple hydrogen isotopes simultaneously co-depositing with slowly grown metal layer is given. The conditions modeled are identical to stationary ion implantation into bulk material with infinite fluence. Ratios of different multiple hydrogen isotopes occupying same trapping sites in metal layers co-deposited from plasma are estimated. It is shown that if hydrogen isotopes have different detrapping energies in regards to the same trap (vacancy, dislocation, etc.), only the concentration of the isotope with highest detrapping energy decreases monotonously with deposition temperature. The uncertainty of tritium concentration in co-deposited layer based on the uncertainty in detrapping energy of tritium and deuterium is evaluated; for an 0.01 eV difference, a >10% tritium concentration uncertainty is predicted.
The oxidation behaviors of C/C composites with various silicon oxycarbide (SiOC) coatings prepared at various deposition temperatures (1300 - 1513 K) were studied. The SiOC coating improved the oxidation resistance of C/C composites by forming dense SiO 2 glass, but such an improvement was sensitive to the deposition temperature. The SiOC coatings prepared at low temperatures exhibited limited oxidation resistance improvement given the appearance of penetrating cracks, fundamentally caused by their thin, amorphous (high elastic modulus), dense, and brittle characteristics. The SiOC coatings prepared at high temperatures had thick, polycrystalline (low elastic modulus), loose, and resilient structures, thus exhibiting higher oxidation resistance.
The physical properties of CdS buffer layers and the interface quality between CdS layer and Cu 2 ZnSn(S,Se) 4 (CZTSSe) absorber have a significant impact on the performance of CZTSSe solar cells. In the present work, five types of CZTSSe solar cells with conventional structure (denoted as CdS- x -cells, x = 55, 60, 65, 70 and 75) were fabricated by using CdS prepared at deposition temperatures of 55, 60, 65, 70 and 75 ℃, respectively, as buffer layer, and influence mechanism of the deposition temperature of CdS layers on power conversion efficiency (PCE) of the CdS- x -cells was investigated. It is found that the PCE of the CdS- x -cells increases from 8.52% to 10.36% as the deposition temperature rises from 55 to 60 ℃ but falls from 10.36% to 7.14% from 60 to 75 ℃. The analysis on the photovoltaic and electrical parameters indicates that the increase in PCE is predominantly derived from the decreased reverse saturated current density (J 0 ), followed by the decreased series resistance (R S ) and increased shunt resistance (R Sh ). The decreased PCE with the further increasing deposition temperature is mainly contributed from the increased J 0 , followed by the decreased R Sh and photogenerated current density (J L ). The influence mechanism of deposition temperature of the CdS layer on PCE is suggested via quantitatively analysis of influence of electrical, optical properties and crystal quality of CdS prepared at various deposition temperatures on J L and electrical parameters of CdS- x -cells. This work is helpful for improvement of PCE of CZTSSe solar cells by modification of properties of buffer layer.
Silicon oxycarbide (SiOC) films on C/C composite substrate were prepared by isothermal chemical vapor deposition (CVD) with hexamethyldisilazane (HMDSN) as precursor. The deposition rate, microstructure, composition and mechanical properties of films prepared at deposition temperature ranging from 1300 K to 1576 K were investigated in details. With increasing deposition temperature, deposition rate increased gradually and reached a maximum value of 42.9 μm/h at 1513 K and then decreased; concurrently, the surface morphology of SiOC film changed from a smooth-dense to a coarse cauliflower, and then into a needle-like granular morphology. The SiOC films were composed of dominant SiC and a few other phases at all temperatures. In addition, the contents of oxygen-enriched units SiO 3 C and SiO 2 increased with deposition temperature due to redistribution reaction of Si –O and Si –C bonds and oxidation . SiOC films prepared at 1373 K showed the highest hardness and elastic modulus for 28.8 GPa and 234.2 GPa, respectively. SiOC films also contained small amounts of Si 3 N 4 and SiCN at all conditions.
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