Etching, Insertion and Abstraction Reactions of Atomic Deuterium with Amorphous Silicon Hydride Films

We report structural and kinetic studies of the reactions of hydride species in amorphous Si films with atomic deuterium (Dat). Infrared (IR) spectroscopy is used to otain Si-H bonding information and direct recoiling methods are used to measure reaction rates. Two kinds of films are prepared by filament-assisted growth from Si2H6, and are characterized by IR spectroscopy. A film containing only monohydride hydrogen is grown at 200degrees C, and a polymer containing tri-, di- and mono-hydride is grown at -110degreesC. Rates of H abstraction by Dat, and Dat insertion into Si-Si bonds, are reported. The abstraction rate of H by Dat in both films is similar to that from well defined H-terminated crystal Si surfaces. The insertion rate into Si-Si bonds in both films is reported for the first time, and is about 1/10 the rate of abstraction. A qualitative study of the etching reaction of Dat with the polymeric film is reported, and a strong temperature dependence is observed.