Polarization-Engineered p-Type Electron-Blocking-Layer-Free III-Nitride Deep-Ultraviolet Light-Emitting Diodes for Enhanced Carrier Transport

Electron leakage is one of the critical challenges in AlGaN ultraviolet (UV) light-emitting diodes (LEDs). In this regard, a p-type AlGaN electron-blocking layer (EBL) has been utilized to suppress electron leakage. However, it affects the hole injection due to the generation of positive polarization sheet charges at the hetero-interface of the EBL and the last quantum barrier (QB). To address this problem, we propose an EBL-free AlGaN UV LED using polarization-engineered graded QBs instead of conventional QBs. The proposed structure could enhance the carrier confinement in the active region and significantly reduces electron leakage due to the progressively increased effective conduction band barrier heights. Substantially, the proposed structure exhibits higher optical power and wall-plug efficiency at 60 mA current injection, which are boosted by ~85.9% and ~53.6% compared to the conventional structure. Such a unique LED design could pave the way for the next generation of high-power deep UV light sources.