A Self-Assembled Double-Island Buffer Structure for Improving GaN-Based Materials Grown on Si Substrates

Abstract

This paper reports a new method to reduce threading dislocation density in GaN epilayers grown on (111) Si substrates by metal-organic chemical vapor deposition. This method utilizes an in- situ SiNx mask to produce a self-assembled double-island structure, which effectively reduces threading dislocation density from 9.6 × 109 cm−2 to 2.6 × 109 cm−2 without using any lithographic and regrowth processes. InGaN light-emitting diodes fabricated on the double-island buffer layer exhibit nearly 20% improvement on the optical output power as well as less energy localization effect, compared to those without the double-island buffer layer. The mechanisms of double-island formation as well as dislocation reduction are proposed based on transmission electron microscopy investigations.