p-d hybridization of the valence bands of AgxCu1-xGaSe2compounds

Polycrystalline compounds of Ag x Cu 1-x GaSe 2 were grown by the Bridgman method. x was varied from 1.0 to 0.0 at intervals of 0.2. The optical absorption spectra of these six samples were measured using a photoacoustic spectrometer. From these spectra the authors determined the A, B and C transition energies of Ag x Cu 1-x GaSe 2 as functions of the silver concentration x. The transition energies E A and E C relative to transition energy E B were used to obtain both the spin-orbit splitting of the valence bands in a cubic field and the crystal-field splitting of the valence bands in the absence of spin-orbit interaction as functions of x. Furthermore, they estimated the fractional p-like character of the uppermost valence bands for various x, under the assumption that the d levels of Ag and Cu contribute to the spin-orbit splitting according to x.