Light extraction structure formation process in DUV-LEDs

In AlGaN-based deep ultraviolet light-emitting diodes (DUV-LEDs), improving light extraction efficiency is a key challenge. One major limiting factor is the large refractive index mismatch between the sapphire substrate and the AlN buffer layer, which causes significant internal reflection. In this study, we propose a novel approach utilizing a sacrificial layer embedded in the epitaxial structure. By applying photoelectrochemical (PEC) etching, the sacrificial layer is selectively removed, allowing for substrate lift-off without damaging the device layers. We report on the design of the epitaxial structure, process optimization, and successful demonstration of the separation technique. This method offers a promising route toward enhancing the light output efficiency of DUV-LEDs, which is critical for their practical deployment in sterilization and sensing applications.