Performance enhancement of AlGaN-based 365 nm ultraviolet light-emitting diodes with a band-engineering last quantum barrier.

In this Letter, the characteristics of the AlGaN-based near-ultraviolet light-emitting diodes with a band-engineering last quantum barrier (LQB) were analyzed experimentally and numerically. The experimental results show that the peak wavelengths of UV-LEDs are around 368 nm with a full width at half-maximum of 12-14 nm, and the optical and electrical properties are improved by using an AlxGa1-xN LQB with a gradually decreasing Al content. The designed LQB can reduce the forward voltage from 4.35 to 4.29 V and markedly enhance LOP by 47.4% at an injection current of 200 mA, compared with the original structure. These improvements are mainly attributed to less electron leakage and higher hole injection efficiency, resulting from the weakened polarization field in the electron-blocking layer (EBL) and LQB, as well as the alleviation of the band bending at the EBL/LQB interface.