Status and challenges in deep UV semiconductor lasers

Despite the rapid progress in III-nitride-based laser diodes, sub-300 nm UV semiconductors lasers have not been realized yet. UV optoelectronic devices have a variety of applications such as sterilization, water purification, spectroscopy, high density optical data storage, and biological sensing. More specifically, UV laser diodes can be used as an alternative to expensive, bulky, and potentially toxic tube lasers. Technical and scientific barriers arise from the lack of proper crystalline substrates and a poor understanding of defect control in the wide bandgap semiconductors. AlGaN-based technology developed on single crystalline AlN substrates and impurity control in the active region offers a pathway to address all these challenges.