Enhanced performance of AlGaN-based deep-UV LED by incorporating carrier injection balanced modulation layer synergistically with polarization-regulating structures

Abstract

A comparable concentration of carriers injected and transported into the active region, that is, balanced hole and electron injection, significantly affects the optoelectronic performance of AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs). In this study, we introduce a novel structure characterized by a carrier injection balanced modulation layer, incorporating a polarization-regulating gradient p-AlGaN in a DUV LED. We conducted a systematic examination of its impact on the carrier injection and transport processes. Theoretical simulations demonstrate the mitigation of abrupt variations in Al content at the interface between electron blocking layer/p-AlGaN and p-AlGaN/p-GaN within the valence bands. Consequently, holes are more likely to be injected into the active region rather than accumulating at these interfaces. Meanwhile, due to the reduced barrier height at the top of the valence band, the holes were efficiently transported into the quantum well and confined with comparable and balanced concentrations of electrons by suppressing overflow, thereby promoting the radiative recombination rate. Compared with the conventional DUV LED, the hole concentration and radiative recombination rate of the designed structure in the final quantum well are significantly increased to 179.8% and 232.3%, respectively. The spontaneous emission intensity achieves nearly twice at the same current injection density. Moreover, the efficiency droop is significantly suppressed when operated at a gradually increasing current density. This study presents a promising approach that can serve as a reference for achieving high-efficiency AlGaN-based DUV LEDs.