The effect of vacancy defects on the electronic characteristics of the β-Ga2O3/AlN interface

Abstract

The effects of oxygen vacancy and gallium vacancy defects on the electronic properties of β-Ga2O3/AlN heterojunction have been investigated in detail using the density functional theory. The Non-Al (VO) and Non-Al (VGa) and Ga-Al(VGa) interface relaxations mainly occur in the horizontal direction, while the others mainly occurs in the vertical direction;The results of the study proved that the relaxation of the Al plane mainly occurs in the horizontal direction, while the relaxation of the N plane mainly occurs in the vertical direction. A comparative analysis of the formation and binding energies with and without the introduction of defects revealed that addition of defects led to a reduction in both energies, resulting in the formation of a more stable interface.The O-Al (VO) model proved to be the most stable with the lowest energy. The formation energy was considered to be −0.583 eV, whereas the binding energy was obtained as −1.901 eV. An analysis of the differential charge density of the introduced vacancy defects revealed that they played a huge role in distribution and transfer of the charges. After introducing vacancies into the interface, new energy levels are generated in the NON-N model with the O vacancy and O-Al model with the O vacancy. But both levels belong to deep levels in the bandgap, which does not affect the band characteristics. The results of study clearly showed that O-Al (VO) model was more suitable for high frequency and high power devices. It also proved that introduction of appropriate defects at the interface can help improve electrical characteristics of these devices, providing theoretical guidance for device preparation.