Phase-pure a-SiC:H films prepared by closed chamber CVD

Abstract

a-SiC:H films were prepared by using a new film deposition process, referred to as closed chamber CVD (CC-CVD). The CC-CVD is a layer-by-layer technique, which repeats a cycle of two steps: (1) deposition of ultra-thin a-Si:C:H layer by common rf-plasma CVD (rf-CVD), and (2) reconstruction of the layer, performed at `etching/redeposition' equilibrium within a closed plasma chamber. In contrast to the common a-Si:C:H, the atomic network of the CC-CVD material is predominantly Si–C bonded. Films of a large optical band gap E g are achieved at low CH 4/SiH 4 gas ratios. The dark conductivity is several orders of magnitude higher than that of the common a-Si:C:H. The CC-CVD films also show a high photoconductivity. The film growth mechanism, resulting in a dramatic modification of the a-SiC:H material, is discussed.