Enhanced hole injection in Ga-polar 290 nm AlGaN-based DUV LEDs with a p-n junction hole accelerator

The limited kinetic energy of holes in AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) poses a challenge in their transportation into the active region across the Alrich electron blocking layer (EBL) and significantly restricts the electrical and optical performance of DUV LEDs. In this work, we propose a hole accelerator structure composing a p-AlxGa1-xN/nAlxGa1-xN junction to improve the hole injection efficiency and explore the mechanism behind the enhanced performance with the Advanced Physical Models of Semiconductor Devices software (APSYS). The built-in electric field of the p-n junction distributes along the [000-1] direction, which can enhance the hole drift velocity and improve the hole injection into the active region. Moreover, with an optimum Al composition of 50%, [000-1] oriented polarization-induced electric field can be generated at the vicinity of both the p-EBL/accelerator and accelerator/hole supplier interfaces, which further boosts the holes into the active region. Besides, the original steep barrier for holes at the EBL/hole supplier interface can be splited into a two-step barrier which is more favorable for hole transportation. As a result, an enhanced optical power by 49.4% and alleviated efficiency droop by 76.3% can be achieved with the proposed p-n junction-based hole accelerator. The results can pave the way for AlGaN-based DUV LEDs towards high-power and high-efficiency applications.