Improved Characteristics of InGaN Multi-Quantum-Well Laser Diodes Grown on Laterally Epitaxially Overgrown GaN on Sapphire

Abstract

InGaN multi-quantum-well laser diodes have been fabricated on fully-coalesced laterally epitaxially overgrown (LEO) GaN on sapphire. The laterally overgrown ‘wing’ regions as well as the coalescence fronts contained few or no threading dislocations. Laser diodes fabricated on the low-dislocation-density wing regions showed a reduction in threshold current density from 8 kA/cm2 to 3.7 kA/cm2 compared the those on the high-dislocation ‘window’ regions. Laser diodes also showed a two-fold reduction in threshold current density when comparing those on the wing regions to those fabricated on conventional planar GaN on sapphire. The internal quantum efficiency also improved from 3% for laser diodes on conventional GaN on sapphire to 22% for laser diodes on LEO GaN on sapphire.