TERMS LINEAR IN K IN THE BAND-STRUCTURE OF WURTZITE-TYPE SEMICONDUCTORS

Wurtzite has the space-group symmetry P6(3)mc. The absence of inversio n symmetry allows linear-k terms in the electronic band structure when the spin-orbit interaction is included. Their existence has been conf irmed in a number of experiments, but no microscopic calculations have been published. In the present paper, we discuss the origin of these linear-k terms using group theory and k . p arguments. The various con tributions to these terms are identified through band-structure models . We present an ab initio calculation, performed with the linear-muffi n-tin-orbital method, of these spin splittings in CdS, CdSe, and ZnO. A renormalization of the valence-band spin-splitting coefficients obta ined in the linear-muffin-tin-orbital calculations was found necessary to correct for errors in the relative energies of the uppermost valen ce bands as compared with the experimental values. We point out that a similar procedure should be used when evaluating masses and other ban d parameters from calculated local-density-approximation band structur es.