Effect of hydrostatic pressure and temperature on theCu2⁢Oelectronic band structure

Abstract

We present extensive experimental and theoretical research aimed at thoroughly examining changes in the electronic structure of Cu2⁢O under the influence of external factors. Hydrostatic pressure and temperature dependencies of optical properties were investigated experimentally using photoreflectance (PR), determining the pressure coefficients of as many as four direct optical transitions at the Γ point. Using state-of-the-art theoretical methods for band-structure prediction (including electron-phonon calculations), we obtained an excellent agreement of theory and experiment for both pressure and temperature properties. After theoretical analysis of excitonic properties, we claim that the change of the binding energy of the Wannier-Mott exciton under pressure turned out to be negligibly small up to applied pressure (17 kbar). We further describe the system in terms of the 12-band 𝑘·𝑝 Hamiltonian, derived in the invariant expansion form, including the strain part. We find parameter values for the 𝑘·𝑝 model based on our accurate band-structure calculations, including a set of absolute deformation potentials for band edges. As a result, we deliver a reliable and computationally efficient methodology for semiconductor device modeling.