Native defects and their complexes in spinel LiGa5O8

Abstract

Recently, LiGa5O8 was identified as a cubic spinel type ultra-wide-bandgap semiconductor with a gap of about 5.36 eV and reported to be unintentionally p-type. Here, we present first-principles calculations of native defects and their various complexes to try to explain the occurrence of p-type doping. Although we find Li vacancies (0.74 eV above VBM) to be shallower acceptors than in LiGaO2 (1.63 eV above VBM), and becoming slightly shallower in complexes with donors such as VO (0.58 eV above VBM) and GaLi antisites (0.65 eV above VBM), these VLi based defects are not sufficiently shallow to explain p-type doping. The dominant defects are donors and, in equilibrium, the Fermi level would be determined by compensation between donors and acceptors and pinned deep in the gap.