Electronic structure of GaAs under strain

Abstract

Results of self-consistent relativistic band calculations for GaAs under hydrostatic as well as uniaxial strain are presented. Deformation potentials related to the splitting of the valence-band edge (${\ensuremath{\Gamma}}_{15}^{v}$) are calculated with and without inclusion of spin-orbit coupling. The trigonal-shear deformation potentials that agree with experiments correspond to an internal-strain parameter $\ensuremath{\zeta}=0.6\ifmmode\pm\else\textpm\fi{}0.1$. The calculated values, 16-19 eV, of the optical deformation potential ${d}_{0}$ are substantially smaller than the published experimental results (\ensuremath{\simeq}41 eV). The ${E}_{0}$ gap obtained in the local-density approximation is 0.25 eV. A method of correcting for this error and for calculating, self-consistently, the lowest $s$-like conduction band is described, and used to derive pressure dependences of the gaps and conduction-band masses. The parameters for this adjustment of the conduction band are determined for zero pressure, and can be kept pressure independent. We find $\frac{(\frac{1}{{m}_{c}^{*}})d{m}_{c}^{*}}{\mathrm{dP}}=0.68\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$ ${\mathrm{kbar}}^{\ensuremath{-}1}$. The pressure at which conduction-band inversion occurs is 30.5 kbar. The value calculated for shear deformation potential ${\mathcal{E}}_{2}^{L}$ is 19 eV for $\ensuremath{\zeta}=0.6$. The spin-orbit-induced splitting of the lowest conduction band for $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}\ensuremath{\parallel}[110]$ and the additional strain-induced splitting are calculated and related to experimental results for spin relaxation of photoexcited electrons.