The Structure of Silicon Oxide Films

The scattering of electron waves by an amorphous material is partly dependent on its structure. The variation of this scattered intensity with angle may be mathematically transformed to give a radial distribution function (r.d.f.) which describes both the position and co‐ordination of sets of atoms. The methods used to obtain the r.d.f. 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. The structure found for amorphous silica films is similar to that determined by X‐rays and amorphous silicon has the expected tetrahedral bonding. It is shown that glow discharge and evaporated silicon oxide films, whose average composition lies between silicon and silica, consist of a mixture of these latter two materials.