Numerical Investigation on the Carrier Transport Characteristics of AlGaN Deep-UV Light-Emitting Diodes

Carrier transport characteristics of AlGaN-based deep-ultraviolet light-emitting diodes (LEDs) are theoretically investigated. Simulation results reveal that hole transport/injection may be severely obstructed by the large potential barrier at the p-electron-blocking layer/p-GaN interface. Under this circumstance, the slope efficiency degrades and electron leakage increases accordingly. By inserting the AlGaN interlayers to form band-engineered staircase p-region, both the transport/injection of holes and I-V characteristic are improved. Moreover, the LED characteristics become less sensitive to the polarization field, which is beneficial for obtaining high LED performance with the LED of high crystalline quality.

I. Introduction

The deep-ultraviolet (DUV) light-emitting diodes (LEDs) are of great interest for various applications, such as the biochemistry, medicine, water purification, and sterilization. Owing to the direct and wide bandgap energy, III-nitride semiconductors such as GaN, AlN, AlGaN, and InAlGaN are promising materials for the realization of high-efficiency DUV light sources [1]. To date, there are a few AlGaN-based DUV LED structures reported in the literature [2]–[6]. Even though efforts have been made to improve the quality of epitaxial growth, several challenges including high threading dislocation density, low light extraction efficiency, and low hole concentration still limit the external efficiency and retard the progress of mass production of DUV LEDs [4]–[6]. Besides the problem of crystal growth, the polarization effect may also influence the DUV LED performance as well.