Valence-band splittings in cubic and hexagonal AlN, GaN, and InN

Modern parameter-free band-structure calculations are applied to the uppermost valence bands near the Gamma point. They are based on a nonlocal exchange-correlation starting point for the iteration of the quasiparticle equation and include spin-orbit interaction. The Ga 3d and In 4d electrons remarkably influence the valence-band splittings. Quasiparticle effects shrink the crystal-field splitting Delta(cf) for GaN and increase the inverted Gamma(1)-Gamma(5) distance for AlN. Beyond the quasicubic approximation, we find a small anisotropy of the spin-orbit splittings. While for AlN Delta(so) does only weakly depend on the crystal structure, variations are found between zinc blende and wurtzite for GaN or InN. (C) 2010 American Institute of Physics. [doi:10.1063/1.3524234]