Influence of the deposition parameters on the transition region of hydrogenated silicon films growth

Hydrogenated microcrystalline and amorphous silicon thin films were prepared by very high frequency plasma-enhanced chemical vapour deposition (VHF PECVD) by using a mixture of silane and hydrogen as source gas. The influence of deposition parameters on the transition region of hydrogenated silicon films growth was investigated by varying the silane concentration (SC), plasma power (P_w), working pressure (P), and substrate temperature (T_s).Results suggest that SC and T_s are the most critical factors that affect the film structure transition from microcrystalline to amorphous phase. A narrow region in the range of SC and T_s, in which the rapid phase transition takes place, was identified. It was found that at lower P or higher P_w, the transition region is shifted to larger SC. In addition, the dark conductivity and photoconductivity decrease with SC and show sharp changes in the transition region. It proposed that the transition process and the transition region are determined by the competition between the etching effect of atomic hydrogen and the growth of amorphous phase.