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

Abstract

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 3.0eV. For the deposition process of nc-SiC, the Egopt of the deposited films varied from 1.9eV to 2.5eV as the filament temperature increased from 1700 to 2100°C. The deposition rate decreased rapidly from 5.74nm/min to 0.8nm/min with increasing TF.