  Defect energy formation, lattice distortions and electronic structure of
cubic In2O3 with Sn, Ga and O impurities were theoretically investigated using
density functional theory. Different types of point defects, consisting of 1 to
4 atoms of Sn, Ga and O in both substitutional and interstitial (structural
vacancy) positions, were examined. It was demonstrated, that formation of
substitutional Ga and Sn defects are spontaneous, while formation of
interstitial defects requires an activation energy. The donor-like behavior of
interstitial Ga defects with splitting of conduction band into two subbands
with light and heavy electrons, respectively, was revealed. Contrarily,
interstitial O defects demonstrate acceptor-like behavior with the formation of
acceptor levels or subbands inside the band gap. The obtained results are
important for an accurate description of transport phenomena in In2O3 with
substitutional and interstitial defects.
