Electronic structure of ZnGeP₂: A detailed study of the band structure near the fundamental gap and its associated parameters

Full-potential linear muffin-tin orbital band-structure calculations of ZnGeP₂ in the local-density approximation (LDA) indicate several close-lying conduction-band minima at different points in the Brillouin zone. Quasiparticle results available for the zinc-blende “parent” compound GaP are used to estimate corrections beyond the LDA. Even including these corrections, ZnGeP₂ appears to be truly indirect rather than pseudodirect, as has been suggested in the literature. The experimental evidence is reviewed. The standard assignment of features in optical data pertaining to the absorption edge is questioned and a tentative new interpretation is presented in light of our multiple conduction-band minima model. Related band-structure parameters, such as band-gap deformation potentials, effective masses at each of the minima, and the valence-band effective Hamiltonian are determined.