The effects of hydrogen dilution on a-Si:H were studied. A-Si:H thin films were prepared by conventional capacitively coupled rf glow discharge PECVD with silane and hydrogen mixture as source gases. Deposition conditions such as substrate temperature, rf power and dilution ratio were varied, but total pressure was fixed. As a result of hydrogen dilution, in some conditions the properties of the sample such as photosensitivity and photoconductivity were improved but at high dilution ratio and high substrate temperature the quality of the film was deteriorated.
Stability under light soaking was studied. By hydrogen dilution, the stability of the samples prepared at low substrate temperature was improved. It was noted that the behavior of degradation was different for the samples made under various substrate temperature. And the correlation between degradation and photosensitivity was observed.
Low substrate temperature (＜200℃) and low rf-power density are suggested as the best condition under which hydrogen dilution might improve the quality of a-Si:H.
