Bias Effects on Morphology and Growth Rate of Glow Discharge a-Si:H Films in a Triode System

We investigated the positive and negative bias effects on the morphology and the growth rate of a glow-discharge a-Si:H film prepared using a triode system. The growth rate increased with the magenitude of the bias, irrespective of its polarity. A columnar structure is promoted if the film is prepared with, an applied positive bias. The film is favorably densified if it is prepared with an applied moderate negative bias. An extremely high negative bias, however, leads to the formation of unfavorable nodules on the film surface. The configurational change of the incorporated hydrogen by the bias is discussed in terms of an inhomogeneous structure composed of a grain-boundary like region and a grain-like region.