Preparation of Wide-Gap Hydrogenated Amorphous Silicon Carbide Thin Films by Hot-Wire Chemical Vapor Deposition at a Low Tungsten Temperature

Hydrogenated amorphous silicon carbide (a-Si_1-xC_x:H) thin films were prepared by hot-wire chemical vapor deposition at a tungsten temperature of 1400°C in methane, silane and hydrogen gas atmosphere, and their properties were investigated. The optical band gap, estimated from Tauc's plot, of a-Si_1-xC_x:H films prepared at a total gas pressure of 1 Torr was 1.79±0.03 eV. On the other hand, the optical band gap of a-Si_1-xC_x:H films prepared at 4 Torr was 2.18 ±0.05 eV. The infrared absorption spectra showed that a-Si_1-xC_x:H films prepared at 4 Torr have more Si–C bonds than those prepared at 1 Torr. These findings indicate that the preparation at a high total gas pressure can lead to higher carbon content, consequently, wider-gap a-Si_1-xC_x:H films, even at a low tungsten temperature.