Reducing the polarization mismatch between the last quantum barrier and p-EBL to enhance the carrier injection for AlGaN-based DUV LEDs

Abstract

In this work, we report an AlGaN-based ∼275 nm deep ultraviolet light-emitting diode (DUV LED) that has AlGaN based quantum barriers with a properly large Al composition. It is known that the increased conduction band barrier height helps to enhance the electron concentration in the active region. However, we find that the promoted hole injection efficiency is also enabled for the proposed DUV LED when the Al composition increases. This is attributed to the reduced positive polarization charge density at the last quantum barrier (LQB) and p-type electron blocking layer (p-EBL) interface, which can suppress the hole depletion effect in the p-EBL. Thus, the hole concentration in the p-EBL gets promoted, which is very helpful to reduce the hole blocking effect caused by the p-EBL. Therefore, thanks to the improved carrier injection, the proposed DUV LED increases the optical power and reduces the forward voltage when compared with the conventional DUV LED.