Ultraviolet Absorption of Insulators. II. Partially Ionic Crystals

Abstract

A wide range of experimental data now indicates that uv structure depends primarily on crystal structure and only secondarily on atomic composition. We assign characteristic structure of ultraviolet absorption to interband transitions at symmetry points of the Brillouin zone. The crystal structures that are discussed are zincblende and wurtzite. The experimental information required for comparison with theoretical calculations is discussed, with special emphasis laid on the importance of polarization studies of the reflectance of hexagonal crystals.