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 (${\Gamma }_{15}^v$) 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 $\zeta =0.6\mathrm{}\pm 0.1$. The calculated values, 16-19 eV, of the optical deformation potential $d_0$ are substantially smaller than the published experimental results (≃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 $\frac{\left(\frac{1}{m_c^{*}}\right)d{m}_c^{*}}{\mathrm{dP}}=0.68\mathrm{}\times {10}^{-2\mathrm{}}$ ${\mathrm{kbar}}^{-1\mathrm{}}$. 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 $\zeta =0.6\mathrm{}$. The spin-orbit-induced splitting of the lowest conduction band for $\overrightarrow{\mathrm{k}}\parallel \mathrm{}\left[110\right]\mathrm{}$ and the additional strain-induced splitting are calculated and related to experimental results for spin relaxation of photoexcited electrons.