Suppressing the luminescence of Vcation-related point-defect in AlGaN grown by MOCVD on HVPE-AlN

Abstract AlGaN materials have a great prospect in ultraviolet and deep-ultraviolet optoelectronic devices, while the point-defects impede their applications. In this report, we successfully suppressed the luminescence of Vcation-related point-defect in AlGaN materials. AlGaN epilayers were grown on AlN/sapphire template by metal-organic chemical vapor deposition and the mixed metal-organic flows were used to pretreat the surface of AlN/sapphire template. The luminescence intensity of (Vcation-complex)2- point-defects was reduced by the pretreatment, demonstrating the favorable suppression effect on the luminescence of (Vcation-complex)2- point-defects. The ephemeral metal-rich condition and metal-droplets on the AlN/sapphire template were believed to be partially responsible for the suppression. It also supported the conception that the 3.90 eV luminescence in AlN originated from the Vcation-related point-defects rather than the CN point-defects. The surface morphology was investigated and an optimized pretreating time of 60 s was obtained. The carrier recombination mechanism was also studied and the results revealed that dislocations not only could act as non-radiative recombination centers, but also could bind the excitons.