Performance Improvement of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes with Multigradient Electron Blocking Layer and Triangular Last Quantum Barrier

The performance improvements of AlGaN-based deep ultraviolet light-emitting diodes (DUV-LEDs) with multigradient electron blocking layer (EBL) and triangular last quantum barrier (LQB) are investigated. The results show that the maximum internal quantum efficiency (IQE) is improved by 44.9% and light output power (LOP) is improved by 58.1% at 200 A cm(-2), exhibiting a tremendous improvement compared to the conventional structure. These improvements are mainly attributed to the fact that both multigradient EBL and triangular LQB can generate negative polarization charges in the graded composition layer, which leads to a significant increase in hole concentration compared to the conventional EBL and LQB structures. Meanwhile, the multigradient EBL can transform the conventional triangular barrier into an arc-shaped barrier, increasing the electron potential barrier height and decreasing the hole potential barrier height. This unique design suppresses electron leakage and enhances hole injection, leading to a significant enhancement of the IQE and alleviation of the efficiency droop.