Effect of film thickness on hydrogenated amorphous silicon grown with hydrogen diluted silane

Thin films of hydrogenated amorphous silicon (a-Si:H) prepared by plasma-enhanced chemical vapor deposition with 10% SiH4 in hydrogen have been studied concerning the effect of film thickness on the hydrogen concentration, interconnected void network and mechanical stress. The hydrogen concentration was determined by nuclear reaction analysis. The interconnected void network was studied by the method of ion exchange in glass substrate. The films were prepared at a substrate temperature in the range of 150-270 degreesC. The results show that at the substrate temperature of 150 degreesC the film starts to grow with an extensive void network, and its structural improvement with thickness is manifested by an increase of the film density. In contrast, at 270 degreesC the film starts to grow with a dense structure, and its improvement is manifested by an increase of the intrinsic compressive stress. The hydrogen concentration does not depend on the film thickness at any substrate temperature. (C) 2002 American Institute of Physics.