Entirely Crack-Free Ultraviolet GaN/AlGaN Laser Diodes Grown on 2-in. Sapphire Substrate

Abstract

We have succeeded in fabricating ultraviolet (UV) GaN/AlGaN laser diodes without any crack generation on a whole 2-in. sapphire substrate using a hetero-facet-controlled epitaxial lateral overgrowth (hetero-FACELO) method. The UV laser diodes lased in the peak wavelength range from 355.4 to 361.6 nm under a pulsed current operation at room temperature. We have also investigated both parameters, material gain and optical-internal loss in GaN/AlGaN multiple quantum wells (MQWs). The actual threshold currents of the UV laser diodes were practically in agreement with the estimated threshold current from these parameters. This layer structure is one of the solutions for the purpose of high-yield production of UV photonic devices.