Improved Wave Function Overlap and Carrier Confinement of AlGaN‐Based Deep‐Ultraviolet Light‐Emitting Diodes with Graded Composition Multiple Quantum Wells

Abstract

Herein, the electron–hole wave function overlaps as well as the carrier confinement are both improved by an inversely graded Al‐composition design in the multiple‐quantum‐well (MQW) active region of deep‐ultraviolet light‐emitting diodes (DUV–LEDs). Simulation results show that at a current of 250 mA, the light output power (LOP) of the DUV–LEDs with graded composition MQWs has achieved a remarkable enhancement of 38.7% as compared to that with conventional MQWs, and the efficiency droop is significantly reduced from 32.2% to 9.3%. The enhanced performance is attributed to the increased wave function overlap of the electrons and holes due to the alleviated polarization electric field. Furthermore, the depth of quantum wells (QWs) is increased by the increased polarization‐induced charges and results in a better carrier confinement in the well layers. In addition, the LOP is further enhanced by 20.5% and the efficiency droop is reduced to 6.2% by engineering the last quantum barrier in the graded MQWs, which is attributed to the further reduction in the electron leakage. The proposed structure provides a valuable guideline for the high‐efficiency DUV–LEDs.