Anomalous decomposition profile of the excited triplet SiH3F: A prediction by a b i n i t i o molecular orbital calculations

Abstract

In search of new starting materials for producing amorphous silicon by plasma chemical vapor deposition, decomposition profiles through triplet states have been studied for fluorosilanes SiHmF4−m (m=0–4) by energy-gradient ab initio molecular orbital calculations with the 6–21G** basis set. Anomalous Si–F bond cleavage at the first stage was concluded for triplet SiH3F, while all the other fluorosilanes decompose through the Si–H bond cleavage. The anomaly observed for triplet SiH3F is due to the positive charge on F and to the negative overlap population of the Si–F bond. Thus, SiH3F is expected to be a unique source for amorphous silicon films.