On the growth mechanism of plasma deposited amorphous silicon thin films

We propose a comprehensive mechanism of amorphous silicon thin film growth by plasma deposition based on results of kinetic Monte Carlo simulations according to a database constructed by first-principles density functional theory calculations. The growth mechanism consists of various surface kinetic events including radical-surface and adsorbed radical-radical interactions, radical-surface diffusion, and surface hydride dissociation reactions. Of particular importance is the radical dissociative adsorption mediated by Si over-coordination defects along the reaction pathway. The proposed mechanism explains fully the experimentally measured surface composition of plasma deposited films under conditions that make the silyl radical the dominant deposition precursor.