Ultraviolet laser diodes grown on semipolar (20(2)over-bar1) GaN substrates by plasma-assisted molecular beam epitaxy

We demonstrate ultra-violet laser diodes emitting at 388 nm grown by plasma-assisted molecular beam epitaxy on semipolar (20 (2) over bar1)GaN substrates under metal-rich conditions. The threshold current density and voltage of 13.2 kA/cm(2) and 10.8 V were measured at room temperature for devices with the laser ridge waveguide oriented along the [(1) over bar2 (1) over bar0] direction. We show smooth, atomically flat surface morphology after growth. The excellent structural quality of the laser heterostructure was corroborated by transmission electron microscopy. (C) 2013 AIP Publishing LLC.