P-μc-Si_1−xGe_x:H thin film by VHF-PECVD

Abstract

In this paper, a series of boron doped microcrystalline hydrogenated silicon-germanium (p-μc-Si_1−xGe_x: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-Si_1−xGe_x: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.

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