MICROCRYSTALLINE SILICON FILMS PREPARED BY VERY HIGH FREQUENCY PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION AT LOW TEMPERATURE

Abstract

Intrinsic microcrystalline silicon films have been prepared using very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) at low temperature. The effect of silane concentration and power density on the deposition rate and crystallinity of silicon films has been investigated. The Raman spectra indicates a phase transition from microcrystalline to amorphous phase at silane concentrations of higher than 6%. A growth rate of microcrystalline films as high as 6.6 A/s is achieved at a silane concentration of 6% and the crystalline volume fraction Xc is 39%. We have also observed that the decrease of power density shifts the phase transition to low silane concentration.