Abstract
AlGaN-based deep-ultraviolet (DUV) laser diodes (LDs) are expected to be applied to various applications such as sterilization, sensing, and laser processing as compact, efficient, and eco-friendly deep-ultraviolet light sources. To realize laser diodes operating in the DUV wavelength range (200 nm to 280 nm), our research group has achieved major breakthroughs such as high-quality AlGaN thin film crystals grown on AlN single-crystal substrates and p-type conductivity control through distributed polarization doping. As a result, pulsed lasing at room temperature was demonstrated. Furthermore, continuous-wave (CW) lasing has been successfully achieved by suppressing dislocation formation through stress concentration suppression and further design improvements. In this presentation, we will review the research results of our group on DUV LD devices and describe the key technologies that played an important role in these achievements.