Raman scattering studies of amorphous Si xGe 1− x:H alloy films produced by hot-filament assisted chemical vapour deposition technique

Abstract

a-Si x Ge 1− x :H films have been produced by employing the hot-filament assisted chemical vapour deposition (HF-CVD) technique for investigation of their structural characteristics using Raman scattering technique. We show here that the HF-CVD technique can be used to produce a-Si x Ge 1− x :H alloy films of desired composition by using extremely low concentrations of GeH 4 gas in SiH 4 gas leading to what is termed as GeH 4 starving filament condition. The mechanism responsible for the growth of the alloy films is discussed and the Raman results have been used to show that the films grown by the HF-CVD technique are structurally better ordered compared to those grown by using the plasma and sputter deposition techniques.