Enhanced optical gain of c-plane InGaN laser diodes via a strain relaxed template with reduced threading dislocation density

Abstract

In this work, we demonstrate a method to reduce the threading dislocation density (TDD) of the previously reported strain relaxed template (SRT) on c-plane. Through the processes of nano-patterning/etching and epitaxial lateral overgrowth (ELO) of GaN, the TDD was reduced from beyond measurable level to 1.8 × 109/cm2. The electrically pumped blue edge emitting laser diodes (EELDs) exhibit much improved device performance than previously reported results, where a threshold current density (Jth) of 7.4 kA/cm2 is demonstrated, with the internal loss as low as 8–10 cm-1. Additionally, the thresholds outperform conventional c-plane EELDs without SRT as the cavity length scales below 1200 µm. Moreover, a more than 50% enhanced material gain than conventional c-plane devices is experimentally demonstrated.