Performance evaluation of tunnel junction-based N-polar AlGaN deep-ultraviolet light-emitting diodes

In this study, an N-polar AlGaN-based deep-ultraviolet (DUV) light-emitting diode (LED) incorporating a tunnel junction (TJ) as the p-side contact layer, named the N-TJ-LED, was proposed. Compared with regular N-polar LEDs (N-LEDs) with a p-GaN contact layer, the N-TJ-LEDs exhibited 50% enhanced internal quantum efficiency, 2.7 times higher light output power at an injection current of 40 mA, and dramatically reduced turn-on voltage. In addition, it was found that the N-TJ-LED can still maintain outstanding device performance at a low p-type doping level in the electron blocking layer and p-AlGaN current injection layer, significantly outperforming the regular N-LED. All these performance enhancements are derived from the higher electron and hole concentration in the active region of the N-TJ-LED, thanks to the TJ-facilitated efficient hole injection and effective electron blocking in the device. The results demonstrated in this work provide an effective strategy for the future experimental optimization of N-polar AlGaN-based DUV LEDs.