Growth and characterizations of GaN-Based LEDs grown on wet-etched stripe-patterned sapphire substrates

The material and electrical properties of GaN-based light-emitting diodes (LEDs) grown on wet-etched stripe-patterned substrates were investigated. Footprint-like patterns, located directly above the inclined groove sidewalls, were found on the as-grown LED surface. Cross-sectional transmission electron microscopy (TEM) showed that 'tumor'-like structures with poor crystal quality were initiated on the inclined sidewalls, seeding dislocation bundles in the subsequently grown crystal. The high dislocation density slowed down the growth above the inclined sidewall, resulting in the uneven morphology. The fabricated devices showed over 30% enhancement in light output power as a result of improvements in both internal and extraction efficiencies.