Impact of the interface vacancy on Schottky barrier height for Au/AlN polar interfaces

Schottky barrier heights (SBHs) at the Au/AlN interface are systemically studied by density functional calculations. Two types of interfaces, including Al- and N-polar interfaces, are constructed to examine the relationship between the SBH and the interfacial atom species. An in-depth exploration is conducted by introducing interfacial aluminum vacancy or nitride vacancy. The results show that the calculated p-type SBH of the Al-polar interface (2.30 eV) is higher than that of the N-polar interface (1.23 eV). Results also show that the SBH of the interface with Al or N vacancies would be higher. More obvious metal-induced gap states (MIGS) can be observed after the introduction of interfacial vacancy site, leading to a stronger Fermi-level pinning at the contact. The derived SBHs are within the reported measurement range. The findings provide an insightful hint for AlN-based devices where Schottky contact matters.