Angle-resolved photoemission study and first principles calculation of the electronic structure of GaTe

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 $\mathit{\text{p}}$-like behavior, with a pronounced anion contribution. The conduction band minimum arises from states with a comparable $\mathit{\text{s}}$- $\mathit{\text{p}}$-cation and $\mathit{\text{p}}$-anion orbital contribution. Spin-orbit interaction appears to specially alter dispersion and binding energy of states of the topmost valence bands lying at $\mathrm{\Gamma }$. By spin-orbit, it is favored hybridization of the topmost $\mathit{\text{p}}$${}_z$-valence band with deeper and flatter $\mathit{\text{p}}{}_x$-$\mathit{\text{p}}{}_y$ bands and the valence-band minimum at $\mathrm{\Gamma }$ is raised towards the Fermi level since it appears to be determined by the shifted up $\mathit{\text{p}}{}_x$-$\mathit{\text{p}}{}_y$ bands.