Continuous-wave operation of GaN-based laser diodes using stress-relaxed epitaxial lateral overgrown GaN on Si substrates

A GaN layer grown using the epitaxial lateral overgrowth method (ELO-GaN) on Si substrates was evaluated in terms of dislocations. ELO-GaN grown by optimized growth conditions has no dark line defects that were previously observed. Analysis revealed that strain relaxation suppressed the dark line defects and suggested that the strain relaxation was caused by high carbon concentration in ELO-GaN. Laser diodes (LDs) with a cavity length of 100 µm were fabricated on this strain-relaxed ELO-GaN on Si. Continuous-wave (CW) operation has been demonstrated at a threshold current density of 5.6 kA/cm² thanks to a significantly reduced threshold current.