Implementation of electron restriction layer in n-AlGaN toward balanced carrier distribution in deep ultraviolet light-emitting-diodes

Abstract

The distribution of electrons and holes inside the multiple-quantum wells is highly non-uniform for AlGaN-based deep ultraviolet light-emitting diodes (DUV-LEDs) due to both insufficient hole injection and excessive electron leakage. A key factor to improve the quantum efficiency of DUV-LED is to reduce the proportion of hot electrons in n-AlGaN through carrier deceleration. In this work, we propose a structure design by introducing an additional Al0.55Ga0.45N/Al0.42Ga0.58N superlattice electron restriction layer between the active region and n-AlGaN for electron deceleration. The superlattice structure not only reduces the mobility of the electrons, which helps to balance the distribution of carriers in the active region, thus, promoting radiative recombination, but also facilitates the lateral transport of the electrons, thus, reducing the current crowding effect through band engineering. Low temperature electroluminescence analysis reveals that the improvement of quantum efficiency is due to both enhanced carrier injection efficiency and radiation recombination efficiency in the active region.