Fabrication of high growth rate solar-cell-quality c-Si:H thin films by VHF-PECVD

Abstract

Several series of Si:H films were fabricated by the very high frequency plasma enhanced chemical vapour deposition (VHF-PECVD) at different substrate temperatures (Ts) and silane concentration (SC=[SiH4]/[SiH4+H2]%). The results of Raman spectroscopy showed structural evolution of the Si:H films with the variation of Ts and SC. The results of x-ray diffraction (XRD) measurements indicated that Ts also influences the crystal orientation of the Si:H films. The modulation effect of Ts on crystalline volume fraction (Xc) is more evident for the high SC, which shows different trend compared to low SC. In addition, the growth rate of the films also showed a regular change with the variation of SC andTs. Different samples in the series showed a similar increase in dark conductivity and a decrease in photosensitivity with increasing Ts and decreasing SC. Device-quality microcrystalline silicon materials were deposited at a high growth rate, characterized by relatively low dark conductivity and relatively high photosensitivity in a certain crystalline range. The microcrystalline silicon solar cell with a conversion efficiency of 4.55% has been prepared by VHF-PECVD.