Appropriateness of HSE06 exchange-correlation energies for post transition metal sesquioxides Ga2O3 and In2O3: Peculiarities in electronic states, momentum densities and thermoluminescence

Abstract

Compton scattering measurements using 59.54 keV γ-rays have been reported for sesquioxides Ga2O3 and In2O3. To precisely compare the experimental and theoretical momentum densities, different exchange and correlation potentials within density functional theory and its hybridisation with Hartree-Fock (PBESOL0 and HSE06) have been considered. χ2 fitting analysis depicts HSE06 as a better choice for both sesquioxides. Present band structures, density of states and UV–vis measurements unambiguously support the use of HSE06 for such oxides and resolves issues related to appropriateness of exchange and correlation potentials. Higher covalent character in Ga2O3 than In2O3 using Mulliken's population is well explained by equal-valence-electron-density scaled CPs. Most prominent and firstly reported features in band structures of In2O3 are presence of parabolic trapping centres at Γ, H and N points with three direct band gaps of similar energy (3.37 eV), which may lead to its higher luminescence properties including potential applications in thermoluminescence dosimeters.