Advantages of Polarization Engineered Quantum Barriers in III-Nitride Deep Ultraviolet Light-Emitting Diodes: An Electron Blocking Layer Free Approach

The p-type AlGaN electron barrier layer (EBL) has been widely used to suppress electron leakage from the active region of AlGaN-based deep ultraviolet (UV) light-emitting diodes (LEDs). However, the conventional EBL can reduce the electron leakage partially and invertedly affects the hole injection due to the formation of positive polarization sheet charges at the hetero-interface. Recently, EBL-free LED structures have received significant attention due to the improved carrier transportation and reduced electron leakage. In this context, we present a novel band-engineered EBL-free AlGaN UV LED structure that uses polarization-controlled composition-graded convex quantum barriers (QBs) instead of traditional QBs and analyzed its performance theoretically. Our proposed structure opens a new path to control the electron leakage due to both a gradual increase in the effective conduction band barrier height and mitigated electrostatic field in the active region. As a result, the internal quantum efficiency and output power of the reported EBL-free structure are boosted significantly compared to the traditional AlGaN UV LED at ~260 nm emission wavelength. Experimental demonstration of such a unique LED design can show the way to generate high-power deep UV light sources for practical applications.