Electronic structure of GaAs under strain

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 (Γ₁₅^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 ζ=0.6±0.1. The calculated values, 16-19 eV, of the optical deformation potential d₀ are substantially smaller than the published experimental results (≃41 eV). The E₀ 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 (1/m_c^*)dm_c^*/dP=0.68×10^-2 kbar^-1. The pressure at which conduction-band inversion occurs is 30.5 kbar. The value calculated for shear deformation potential E₂^L is 19 eV for ζ=0.6. The spin-orbit-induced splitting of the lowest conduction band for k⃗∥[110] and the additional strain-induced splitting are calculated and related to experimental results for spin relaxation of photoexcited electrons.