The Advantages of AlGaN-Based Ultraviolet Light-Emitting Diodes With Al Content Graded AlGaN Barriers

A novel five-period AlGaN/AlGaN multiple quantum wells light-emitting diodes (LEDs) structure with Al content graded AlGaN barriers is designed in order to improve the electrical and optical performance of ultraviolet LEDs (UV-LEDs), and the effects are analyzed by using the APSYS simulation programs. The results show that the effective potential height for electrons is increased, and simultaneously the effective potential height for holes is decreased with the increased number of graded AlGaN barriers, which contributes to less electron leakage and better hole injection efficiency. Thus, the internal quantum efficiency and light output power are significantly improved, and the efficiency droop is also mitigated effectively as the number of graded AlGaN barriers increases. However, there is an undesired peak emission in the last barrier when it is replaced by the graded AlGaN barrier.