Native point defects and dangling bonds in α-Al2O_3

摘要

We performed hybrid functional calculations of native point defects and dangling bonds (DBs) in α-Al2O_3 to aid in the identification of charge-trap and fixed-charge centers in Al2O_3/III-V metal-oxide-semiconductor structures. We find that Al vacancies (V_(Ai)) 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 ～2 eV of the conduction band. Oxygen vacancies (V_O) introduce donor levels near midgap and an acceptor level at ～ 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 α-Al_2O_3 and III-V semiconductors, our results indicate that V_O and Al DBs act as charge traps (possibly causing carrier leakage), while V_(AI), Al_i, O_i, and O DBs act as fixed-charge centers in α-Al_2O_3/III-V metal-oxide-semiconductor structures.