Review on the Progress of AlGaN-based Ultraviolet Light-Emitting Diodes

AlGaN-based materials have exhibited considerable potential for fabricating ultraviolet (UV) light-emitting diodes (LEDs) owing to their direct, wide, and adjustable energy bandgap. AlGaN-based devices have extensive applicability owing to their stable physico-chemical properties. With decades of research effort, significant progress has been achieved in enhancing the working efficiency of AlGaN-based LEDs by optimizing the crystalline quality, doping efficiency, and device design. In this review, methods to obtain high-quality AlGaN-based materials, achieve high doping efficiency, and design UV-LED structures are summarized and discussed. Finally, the issues that need to be addressed in AlGaN-based UV-LED devices are highlighted.