P-μc-Si1−xGex:H thin film by VHF-PECVD

Abstract

In this paper, a series of boron doped microcrystalline hydrogenated silicon-germanium (p-μc-Si1−xGex:H) was deposited by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) from SiH4 and GeF4 mixtures. The effect of GeF4 concentration on films’ composition, structure and electrical properties was studied. The results show that with the increase of GeF4 concentration, the Ge fraction x increases. The dark conductivity and crystalline volume fraction increase first, and then decrease. When the GC is 4%, p-μc-Si1−xGex:H material with high conductivity, low activation energy (σ=1.68 S/cm, E g= 0.047 eV), high crystalline volume fraction (60%) and with an average transmission coefficient over the long wave region reaching 0.9 at the thickness of 72 nm was achieved. The experimental results were discussed in detail.