Low Threshold Current Density InGaN Based 520-530nm Green Laser Diodes on Semi-Polar {20(2)over-bar1} Free-Standing GaN Substrates

Green laser diodes (LDs) on the {20 (2) over bar1} 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 f{20 (2) over bar1} 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 theta(perpendicular to) and parallel theta(parallel to) beam divergence angles at half power of the {20 (2) over bar1} green LDs are 24 and 11 degrees, respectively. From the viewpoint of the device characteristics, especially the threshold current density, we conclude that the green LDs on the {20 (2) over bar1} plane GaN substrates have the essential advantage for obtaining efficient green LDs. (C) 2010 The Japan Society of Applied Physics