High Hole Injection for Nitrogen-Polarity AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes

High hole injection is desired for improving the performance of AlGaN-based deep-ultraviolet (DUV) light-emitting diodes (LEDs). In this work, we adopted a compositionally graded p-Aly1Ga1-y1N/Al0.85Ga0.15N superlattice (SL) structure in a nitrogen-polarity DUV LED. Our numerical simulation results show that this SL structure is very beneficial to the hole injection into the active region, and leads to a low turn-on voltage and device resistance. This is significant because a low device resistance means a low power consumption and a high wall-plug efficiency. Meanwhile, a DUV LED with compositionally graded SL has a peak internal quantum efficiency (72%) that is much higher than that of the reference DUV LED without an SL (56%). This work provides an attractive approach to effectively injecting holes into the active region of a nitrogen-polarity AlGaN-based DUV LED.