Valence band structure of some chalcopyrite compounds

Abstract

It is shown that if the quasi-cubic model is used in the analysis of the variation of the valence to conduction band transition energies as a function of temperature, the values of spin-orbit and crystal-field splittings and their temperature variations so determined are inconsistent with those from X-ray diffraction measurements of lattice parameters and tetragonal distortion. Therefore the previously published results for five compounds have now been analyzed in terms of a recently developed theoretical model which takes into account the effects of p-d hybridization on both spin-orbit and crystal-field splittings. The analysis gives values of a dimensionless parameter M/E which is a measure of the interaction between the p and d states forming the valence bands and which determines the fractional d-like character (1 − α ) of those bands. The variations of M/E and (1 − α ) with temperature have been determined for each compound considered.