Band structure ofCdGeAs2near the fundamental gap

Abstract

First-principles band structure calculations were carried out for the chalcopyrite semiconductor ${\mathrm{CdGeAs}}_{2}$ using the linear muffin-tin orbital method, including spin-orbit coupling. The emphasis of the analysis is on the band gaps and energy band splittings near the fundamental gap. The gap underestimate due to the local-density approximation is corrected using information on quasiparticle calculations for the parent compound GaAs. The experimental information on optical transitions near the gap is reviewed critically in the light of our calculations. The polarization dependence and the pseudodirect nature of some of the transitions is discussed. The effective masses of the conduction band and valence bands are derived from the calculated band structure. A generalization of the Luttinger Hamiltonian for chalcopyrite is presented and its parameters determined.