Efficiency- and lifetime-limiting effects of commercially available UVC LEDs: a review

Abstract Light emitting diodes (LEDs) that emit in the ultraviolet (UV) wavelength range can be used in a wide range of application from material processing and sensing to disinfection and sterilization. Therefore, these emitters have gained considerable interest over the last decade, and their development has shown impressive progress with respect to output power, efficiency, and lifetime. These UV-LEDs are based on the AlGaN material system, and the emission wavelength depends primarily on the Al-Ga ratio. In spite of their development, the intrinsic technologies in these semiconductor devices are still not as mature as their InGaN-based counterparts emitting in the visible range, which are widely used for white light applications. For the latter, significant knowledge about the material system, epitaxy, front- and backend processing and packaging has been gained over the last 30 years of research, development, and commercialization. While some of this knowledge can be adopted for UV-LEDs, the shift from the InGaN to the AlGaN material system and the increased photon energy raises new challenges and partly requires new concepts and solutions for commercial market adoption. This review is intended to give a snapshot of currently available commercial UVC LED technology and devices and provide an overview of the performance and reliability that commercial AlGaN-based UVC LEDs now achieve. It also aims to create awareness of the challenges and special aspects observed for these emitters, which may be instrumental in the development of optimized UVC LED-based applications such as disinfection systems.