Effects of Different Point Defects on the Electronic Properties of III–V Al_0.5Ga_0.5N Photocathode Nanowires

AlxGa1−xN nanowires are the key materials for next-generation ultraviolet (UV) detectors. However, such devices have a low quantum efficiency caused by the introduction of defects and impurities throughout the preparation process of nanowires. Herein, the effects of different interstitial defects and vacancy defects on the electronic structure of Al0.5Ga0.5N nanowires are investigated using density functional theory calculations. Our results successfully discovered that only the formation of an N interstitial defect is thermally stable. In addition, the introduction of different defects makes the different nanowires exhibit n-type or p-type characteristics. Additionally, different defects lead to a decrease in the conduction band minimum in band structures, which is the major cause for the decrease in work function and increase in electron affinity of Al0.5Ga0.5N nanowires. What is more, the calculation of the partial density of states also proved that the interstitial defects contribute to a re-hybridization of local electron orbitals and then cause more significant movement of the electron density. Our investigations provide theoretical guidance for the pursuit of higher-quantum-efficiency ultraviolet (UV) detectors.