Formation of α-Si1−xCx:H and nc-SiC films grown by HWCVD under different process pressure

In this work, hydrogenated amorphous silicon carbide (α-Si1−xCx:H) and nanocrystalline SiC (nc-SiC) thin films were deposited by hot wire CVD (HWCVD) using SiH4/C2H2/H2 gas mixtures. It was found that the films prepared under low gas pressure were α-Si1−xCx:H and those prepared under high gas pressure were nc-3C-SiC. The α-Si1−xCx:H films showed enhanced density of C–Hn and Si–C bonds with increasing C2H2 fraction, which induced an increase in optical gap from 1.8 to 3.0 eV. For the deposition process of nc-SiC, the Eg opt of the deposited films varied from 1.9 eV to 2.5 eV as the filament temperature increased from 1700 to 2100 °C. The deposition rate decreased rapidly from 5.74 nm/min to 0.8 nm/min with increasing TF.