Status of the growth and fabrication of AlGaN-based UV laser diodes for near and mid-UV wavelength

In this article, the development of mid-UV laser diodes based on the AlGaN materials system is reviewed. The targeted wavelength for these lasers covers the range from 200 to 350 nm. After introducing UV laser diodes and explaining their applications, the challenges in growth, design, and fabrication are discussed. In addition, recent results from optically and electrically injected UV laser diodes are presented. Finally, we will discuss possible pathways to improve performance and give an outlook on the expected development of UV laser diodes in the near future. Graphical abstract