Theory of defect formation in the glow-discharge deposition of phosphorus-doped hydrogenated amorphous silicon

A quantitative theory (with no fitted parameters) of the doping of n-type hydrogenated amorphous silicon deposited by glow discharge from phosphine-silane mixtures is presented. Film growth results from the reaction of neutral Si dangling bonds on the film surface with ${\mathrm{SiH}}_3$ radicals. Fourfold-coordinated P donors are produced by the reaction of ${\mathrm{PH}}_3$ with positively charged Si dangling bonds. This theory explains the dependence of the donor concentration, the dangling-bond concentration, and the Fermi level of the film on the phosphine concentration in the discharge.