Laser diodes with 353 nm wavelength enabled by reduced-dislocation-density AlGaN templates

We fabricated optically pumped and electrically injected ultraviolet (UV) lasers on reduced-threading-dislocation-density (reduced-TDD) AlGaN templates. The overgrowth of sub-micron-wide mesas in the Al 0.32 Ga 0.68 N templates enabled a tenfold reduction in TDD, to (2–3) × 10 8 cm −2 . Optical pumping of AlGaN hetero-structures grown on the reduced-TDD templates yielded a low lasing threshold of 34 kW/cm 2 at 346 nm. Room-temperature pulsed operation of laser diodes at 353 nm was demonstrated, with a threshold of 22.5 kA/cm 2 . Reduced-TDD templates have been developed across the entire range of AlGaN compositions, presenting a promising approach for extending laser diodes into the deep UV.