The electronic band structure of GaTe has been calculated by numerical atomic orbitals density-functional theory, in the local density approximation. In addition, the valence-band dispersion along various directions of the GaTe Brillouin zone has been determined experimentally by angle-resolved photoelectron spectroscopy. Along these directions, the calculated valence-band structure is in good concordance with the valence-band dispersion obtained by these measurements. It has been established that GaTe is a direct-gap semiconductor with the band gap located at the Z point, that is, at Brillouin zone border in the direction perpendicular to the layers. The valence-band maximum shows a marked \textit{p}-like behavior, with a pronounced anion contribution. The conduction band minimum arises from states with a comparable \textit{s}- \textit{p}-cation and \textit{p}-anion orbital contribution. Spin-orbit interaction appears to specially alter dispersion and binding energy of states of the topmost valence bands lying at Γ. By spin-orbit, it is favored hybridization of the topmost \textit{p}z-valence band with deeper and flatter \textit{px}-\textit{py} bands and the valence-band minimum at Γ is raised towards the Fermi level since it appears to be determined by the shifted up \textit{px}-\textit{py} bands.
@article{arxiv.cond-mat/0110060,
title = {Angle-resolved photoemission study and first principles calculation of the electronic structure of GaTe},
author = {J. F. Sanchez-Royo and J. Pellicer-Porres and A. Segura and V. Munoz-Sanjose and G. Tobias and P. Ordejon and E. Canadell and Y. Huttel},
journal= {arXiv preprint arXiv:cond-mat/0110060},
year = {2009}
}