Oxygen and point defect-related luminescence in AlN epitaxial layers grown by MOCVD

The optical properties of aluminum nitride (AlN) materials were investigated using cathodoluminescence (CL), revealing two deep-level related emission peaks located at 340 nm and 380 nm. These emission peaks are similar to the "yellow luminescence peak" observed in GaN materials. By increasing the acceleration voltage, it was found that the intensity of these peaks remained unchanged initially and then increased. Additionally, an increase in the injected current led to the emergence of a new emission peak at 320 nm. The tests indicated that these deep-level emissions are related to oxygen atoms and aluminum vacancy defects. Further investigations showed that controlling the TMAl injection, NH₃ injection, and growth pressure could suppress the formation of oxygen atoms and point defects.