Boosting Performance of AlGaN-Based Ultraviolet-C Light-Emitting Diodes via High-Quality AlN Template

Abstract

Ultraviolet-C light-emitting diodes (UVC LEDs) have exhibited promising future on the pursuit of sustainable and environmental-friendly germicidal irradiation source for the next generation. Nevertheless, owing to the large lattice mismatch between the AlN buffer template and sapphire substrate, the current AlGaN-based UVC LEDs are subjected to severe compressive strain and high dislocation density. Here we propose a paradigm to achieve high-quality AlN buffer template via the nucleation layer (NL) modification, growth mode regulation, and indium (In) doping modulation. Consequently, a defect-reduced, strain-controlled, and atomically flatten AlN film is achieved on the flat sapphire substrate (FSS). Furthermore, a remarkable enhancement on electroluminescence performance was observed in our UVC LED via using the proposed AlN buffer template. It is noted that our UVC LED presents a remarkable improvement on the external quantum efficiency (EQE), which is almost 90% greater than that of its referred UVC LED grown on the conventional AlN buffer template. Our work is able to supply a new horizon in the development of the excellent UVC light sources for biomedical testing, water/air purification, and another relevant fields.