Calculation of optical excitations in cubic semiconductors. I. Electronic structure and linear response

Abstract

The electronic structures and the linear optical dielectric functions of 18 cubic semiconductors are studied by the first-principles orthogonalized linear-combination-of-atomic-orbitals (OLCAO) method in the local-density approximation. The crystals studied include the group-IV semiconductors C, Si, and Ge; the III-V compounds AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, InSb; and the II-VI semiconductors ZnS, ZnSe, ZnTe, CdS, CdSe, and CdTe. Results are presented for the band structures, for the density of states, and for the real and imaginary parts of the linear dielectric functions for photon energies up to 12 eV. The results are compared with other existing calculations and experimental data. Some interesting correlations and trends among the 18 semiconductors studied are pointed out, and possible problems with the optical excitation calculation are discussed. These results provide the groundwork for the calculation of nonlinear optical properties on these crystals using the full band-structure approach in the two papers to follow. It is argued that optical excitations in semiconductors can be efficiently carried out using the OLCAO method without resorting to empirical methods or model studies. The present calculation gives band gaps larger than the well-converged result of first-principles pseudopotential calculations. The consequence of this difference on the optical properties is discussed.