The optical properties of silicon carbide thin films prepared by HWCVD from pure silane and methane under various total gas partial pressure

Optical properties of amorphous and nanocrystalline silicon carbide (SiC) thin films prepared by hot wire chemical vapor deposition (HWCVD) from silane (SiH₄) and methane (CH₄) gases under various total gas partial pressures are investigated. The variation of structure and optical properties of the films as a function of total gas partial pressure are studied using FTIR spectroscopy, Raman scattering spectroscopy, and UV–vis-NIR spectroscopy. Optical constants of the SiC films such as absorption coefficient, optical band gap, and refractive index are determined, and the significant correlation between the optical, structural and chemical composition of the films are discussed. The results indicated that the total gas partial pressure and deposition pressure have a strong influence on the structure of the films and therefore significantly control their optical parameters. Consequently, suitable deposition conditions for obtaining SiC films with desired optical and structural properties could be selected. (paper)