POSTHYDROGENATION STUDY OF A-SI FILMS GROWN BY REACTIVE MAGNETRON SPUTTERING

Amorphous silicon thin films were deposited by dc reactive magnetron s puttering and posthydrogenated in order to investigate the H diffusion kinetics in a network originally free of H. A flux of atomic H was ge nerated by dissociation of molecular hydrogen on a hot filament. Secon dary ion mass spectroscopy was used to characterize the H profiles at various stages of diffusion. H profiles measured from secondary ion ma ss spectroscopy can be fitted by a complementary error function. The H diffusion exhibits a dispersive behavior, and the diffusivity in the a-Si is about I X 10(-15) cm2 s-1 at 340-degrees-C and t = 240 min. Th e dispersive parameter alpha was estimated to be approximately 0.4. Th e activation energy was approximately 0.4 eV. In order to improve the sensitivity at low concentration, posthydrogenation was also done with deuterium. Secondary ion mass spectroscopy analysis shows that at hig h D concentration the profile follows a complementary error function b ehavior, while at low concentration D profile follows an exponential d ecay. These results show that the posthydrogenation in dc magnetron sp uttered amorphous silicon can be described by the combined effects of deep and shallow traps.