The structure of amorphous silicon nitride films

Abstract

Abstract In an amorphous material the scattered intensity of electron waves depends, in part, on its structure. The variation of the scattered intensity with angle may be mathematically transformed to give a radial distribution function (RDF) which describes both the position, number and type of atoms around an origin atom. The methods used to obtain the RDF from the structurally dependent intensity and the elimination of errors are described. To determine the scattered intensity experimentally, the electron diffraction pattern is scanned across a small aperture and the open circuit voltage developed in a silicon solar cell is measured. These methods have been used to determine the structure of amorphous silicon nitride films prepared by the glow discharge technique. By changing the ratio of ammonia to silane gases, the average composition of the deposit may be varied from silicon to silicon nitride. The effect of these and other deposition parameters on the structure of the films is described. The structure of these films is shown to consist of a mixture of silicon and silicon nitride. The effect of inelastic scattering on the RDF is discussed and the validity of the results confirmed.