Influence of Deposition Conditions on Properties of a-SiGe:H Prepared by Microwave-Excited Plasma CVD

The influence of the deposition conditions on properties of a-SiGe:H prepared by the microwave-excited plasma CVD was examined. Highly photoconductive a-SiGe:H alloys were obtained at the pressures lower than 0.8 mTorr when the substrate was heated to 200degC. The photoconductive property of a-SiGe:H deteriorated when the microwave power was decreased. Similar deterioration was observed when the deposition pressure was increased. It was suggested that the deterioration of the photoconductive property was caused by the depression of SiH 4 decomposition. The photoconductivity of a-SiGe:H alloys increased with the decrease of the deposition pressure even though the amount of the isolated SiH 2 bonds in the film also increased with the decrease of the deposition pressure. The deposition mechanism inducing this deposition pressure dependence was discussed.