Room-Temperature Continuous-Wave Electrically Driven Semipolar (20(2)over-bar1) Blue Laser Diodes Heteroepitaxially Grown on a Sapphire Substrate

Growth of semipolar GaN laser diodes (LDs) on low-cost and large-size foreign substrates is crucial yet remains very challenging. In this study, we report the world's first continuous-wave (CW) electrically driven semipolar blue LDs at room temperature heteroepitaxially grown on a 4-in. sapphire substrate. The semipolar (20 (2) over bar1) GaN material grown on sapphire substrate exhibits high crystal quality from the X-ray diffraction and transmission electron microscopy measurements. The AIGaN-cladding free semipolar blue LDs utilizing thin p-GaN/indium tin oxide (ITO) cladding structure show a lasing peak at 456 nm, a threshold current density of 6.1 kA/cm(2), and a high output power (P-0) of 1.03 W at 2.8 A under pulsed operation condition. Moreover, the semipolar blue LDs exhibit a CW P-0 of 243 mW at room temperature. The emission light from the semipolar blue LDs is 100% polarized. These results mark a significant breakthrough in substantially reducing the cost of semipolar LDs and expediting the development of future semipolar GaN LDs and their applications.