The complex dielectric constant frequency spectra of vapor‐deposited amorphous Se&sngbnd;Bi and Se&sngbnd;Bi&sngbnd;As films were measured as a function of heat treatment near the glass transition temperature. The observed dielectric dispersions have been attributed to interfacial polarization arising from a layering of alternate high‐bismuth and low‐bismuth amorphous phases parallel to the surface of the film. Theoretical equations based on this interfacial polarization model have been used to reproduce the observed dielectric behavior. The model can correctly fit the observed loss peak frequencies and amplitudes and the increase of the peak frequencies with increasing time of heat treatment for lower‐bismuth‐concentration films (<5.0 at.% Bi). At higher bismuth concentrations conducting paths must be proposed in order to account for the very large dispersion peaks and low‐frequency dielectric constants which are observed. These paths occur either through individual high‐bismuth layers or through the bulk of the film. The addition of arsenic to the low‐bismuth‐concentration films increases the over‐all conductivity and causes a conductivity maximum with heat treatment in the high‐conductivity layers. In the high‐bismuth‐concentration films the arsenic tended to stabilize the amorphous phases of the film.