First-principles analysis of precursor-surface reaction pathways relevant to plasma deposition of silicon thin films

Abstract

Passivation of silicon dangling bonds and abstraction of hydrogen by growth precursors are among the fundamental atomic-scale processes that determine the growth of hydrogenated amorphous silicon thin films during plasma-enhanced chemical vapor deposition from SiH/sub 4//H/sub 2/ containing discharges. Using results of first-principles density functional theory calculations, combined with images of planar intersections of the three-dimensional valence electron density distribution, we determine the optimized reaction pathways and energetics of dangling bond passivation and hydrogen abstraction reactions. Both reactions are found to be barrierless and exothermic in accordance with the experimentally observed temperature-independent growth rate of amorphous Si thin films.