Low Threshold Current Density InGaN Based 520–530 nm Green Laser Diodes on Semi-Polar {2021} Free-Standing GaN Substrates

Green laser diodes (LDs) on the {2021} plane exhibit lower threshold current densities, nearly half of those on the c -plane in the green region between 520–530 nm. The threshold current of a typical {2021} green LD lasing at 525.5 nm under room temperature cw operation is 51.1 mA, which corresponds to a threshold current density of 4.3 kA/cm 2 . The threshold voltage is 6.38 V. The characteristics temperature T 0 is measured to be 175 K. The perpendicular θ ⊥ and parallel θ || beam divergence angles at half power of the {2021} green LDs are 24 and 11°, respectively. From the viewpoint of the device characteristics, especially the threshold current density, we conclude that the green LDs on the {2021} plane GaN substrates have the essential advantage for obtaining efficient green LDs.