Spin-orbit splitting in crystalline and compositionally disordered semiconductors

Abstract

The electronic structures of C, Si, Ge, $\alpha -\mathrm{Sn}$, GaP, GaAs, GaSb, InP, InAs, InSb, and ZnSe are studied using a tight-binding approach which includes spin-orbit interactions. The spin-orbit splittings ${\mathrm{\Delta }}_0$ and ${\mathrm{\Delta }}_1$ are related to atomic spin-orbit splittings and optical gaps. The variation of ${\mathrm{\Delta }}_0$ as a function of chemical composition is studied for a number of alloy systems. It is shown that the nonlinear dependence of ${\mathrm{\Delta }}_0$ on alloy composition is a disorder-induced effect. The bowing parameter is calculated in terms of tight-binding parameters and band gaps.