First-principles study of the elastic tensor of GaP at high electronic temperature

Gallium phosphide (GaP) in the cubic zinc-blende structure is a wide bandgap III-V semiconductor used in electronic devices due to its electroluminescent properties. Despite this importance for optoelectronics, the response of its three-element elastic tensor to illumination is unknown. We use density functional theory to investigate changes in the elastic moduli under photoexcitation. We assume a thermalized photoexcited state represented using hot-electron Fermi distributions of Kohn-Sham occupation numbers, with electronic temperatures between 0.1 eV to 1.0 eV, corresponding to 1.2 to 11,606 K and excited-carrier densities of up to 1022 cm- 3. Ground-state elastic constants computed in this work agree with prior experimental and simulation results. When computing the elastic moduli for increasing electronic temperatures, the elements of the elastic tensors change by up to 61% and approach each other. Based on the Born stability criteria the material remains stable under all electronic temperatures.