Electronic and optical properties of highly complex Ga2O3 and In2O3 polymorphs using approximate quasiparticle DFT+A−1/2

Ga2O3 and In2O3 are promising wide-gap semiconductors for application in trans- parent electronics and ultraviolet optoelectronics. Their pronounced polymorphism leads to varying materials properties with the actual crystal structure. The underly- ing atomic geometries are taken from total energy optimizations within the density functional theory with an appropriate exchange-correlation functional. The precise description of their electronic structures is a challenging task even for the most sophisticated quasiparticle (QP) methods. We apply the fast and efficient but approximate DFT+A−1/2 method to predict fundamental gaps, interband energies and d-level positions of five Ga2O3 and five In2O3 polymorphs in an accurate way, even for polymorphs with 160 atoms in the unit cell. The resulting electronic structures are used to pre- dict dielectric and optical spectra. The resulting effective band masses and dielectric tensors are used to estimate binding energies of band edge excitons. All results are dis- cussed along the polymorph geometry or symmetry and compared with experimental and theoretical data available.