High Efficiency Deep Ultraviolet Light-Emitting Diodes With Polarity Inversion of Hole Injection Layer

In this work, we investigate the performance improvement of N-polar AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) by the inversion of the hole injection layer from N-polar to Ga-polar. The influence of different inversion points on the performance and the energy band of DUV LED is systematically studied, and the principle of performance improvement of DUV LED is explained in detail through the analysis of the energy band. Furthermore, according to the simulation results and practical application, an appropriate inversion point is selected. Under the current of 120 mA, with polarity inversion of the hole injection layer, the light output power of the DUV LEDs increases from 21.34 mW to 29.71 mW, and the applied voltage reduces from 16.06 V to 9.63 V. The DUV LED with polarity inversion has a 132% increase in wall-plug efficiency (WPE) compared with the DUV LED which is totally along [000-1] direction. Therefore, polarity inversion is an effective way to achieve high-performance UV-LEDs.