X-Ray Photoemission Valence-Band Spectra and Theoretical Valence-Band Densities of States for Ge, GaAs, and ZnSe

The first high-resolution valence-band x-ray photoemission spectra for Ge, GaAs, and ZnSe are compared with pseudopotential density-of-states calculations. The general agreement between the experimental and theoretical results is quite good. For ZnSe the photoemission spectrum shows the $\mathrm{Zn} 3d$ states to be higher in energy than the lowest valence-band $s$ state. In order to obtain this ordering of states in the theoretical calculation, a pseudopotential with an explicit energy dependence is required.