Study on the fabrication of UV LED based on Au/i-AlN/n-GaN structure and the effect of operating temperature on the carrier transmission and electroluminescence characteristics

GaN-based light-emitting diodes (LEDs) have important applications in medical diagnostics, sterilization, and other fields. However, the mismatch of p-type materials usually makes it difficult for conventional pn-type GaN-based LEDs to obtain pure ultraviolet (UV) emission. In this paper, a series of metal-insulator-semiconductor (MIS)-type diodes with Au/i-AlN/n-GaN structure were prepared by varying the deposition time of AlN films, and the effects of ambient temperature on their electrical and electroluminescence (EL) properties were investigated. The Au/i-AlN/n-GaN diode achieved high-purity UV emission, and the device had the lowest turn-on voltage and the strongest EL intensity when the deposition time of AlN is 40 min. In addition, the effect of ambient temperature on the EL performance of the MIS-type LED was investigated, and the emission was attenuated due to thermal effects at temperatures above 40℃. Finally, we clarified the source of holes from the energy band structure and discussed the luminescence mechanism of the device. The results show that the MIS structure is an attractive choice to effectively realize the UV emission of GaN-based LEDs.