Structural Studies on Hydrogenated Amorphous Germanium-Carbon Films Prepared by RF Sputtering

Abstract

ESR signals for hydrogenated amorphous Ge–C alloy films prepared by magnetron sputtering were deconvoluted into signals originating from a Ge dangling bond and a C dangling bond. It was determined from the results of the deconvolution that the number of Ge dangling bonds per Ge atom is ten to sixty times larger than that of C dangling bonds per C atom. In contrast to the case of Ge–Si alloy films, in which the number of Ge dangling bonds per Ge atom decreases by increasing the Si content because of the increase in the density of Si–H bonds, the number of Ge dangling bonds per Ge atom increases by increasing the C content in Ge–C alloy films, although the density of C–H bonds increases. This finding may be caused by an increase in the structural randomness because the difference in the covalent bond radius between Ge and C is quite large.