N-AlGaN Free Deep-Ultraviolet Light-Emitting Diode with Transverse Electron Injection

For the first time, the n-AlGaN free deep-ultraviolet light-emitting diode (DUV-LED) with transverse electron injection by selective area regrowth (SAG) n(+)-GaN is demonstrated. The multiple quantum wells (MQWs) and upper layers of the transverse structure LEDs that deposited directly on the AlN template exhibit lower threading dislocation density and better surface morphology compared to conventional structure LEDs with thick n-AlGaN layer. The internal quantum efficiency of the transverse structure LED estimated by temperature-dependent photoluminescence is 95%, which is almost twice higher than that of the conventional structure LED (48%). The electroluminescence intensity of transverse structure LEDs is more than twice that of the conventional structure LEDs. Furthermore, the high crystal quality of MQWs enables transverse structure LEDs to emit shorter peak wavelengths (251-254 nm) and narrower full width at half maximums (10.1-10.7 nm). This study demonstrates that by adopting SAG n(+)-GaN as an electron injection layer, the n-AlGaN free transverse structure LEDs can be realized, enabling a substantial improvement in DUV-LEDs that are generally based on poor crystal quality n-AlGaN.