Native point defects and dangling bonds in α-Al2O3

We performed hybrid functional calculations of native point defects and dangling bonds (DBs) in alpha-Al2O3 to aid in the identification of charge-trap and fixed-charge centers in Al2O3/III-V metaloxide-semiconductor structures. We find that Al vacancies (V-Al) are deep acceptors with transition levels less than 2.6 eV above the valence band, whereas Al interstitials (Al-i) are deep donors with transition levels within similar to 2 eV of the conduction band. Oxygen vacancies (V-O) introduce donor levels near midgap and an acceptor level at similar to 1 eV below the conduction band, while oxygen interstitials (O-i) are deep acceptors, with a transition level near the mid gap. Taking into account the band offset between alpha-Al2O3 and III-V semiconductors, our results indicate that V-O and Al DBs act as charge traps (possibly causing carrier leakage), while V-Al, Al-i, O-i, and O DBs act as fixed-charge centers in alpha-Al2O3/III-V metal-oxide-semiconductor structures. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4784114]