Spatial correlation between optical properties and defect formation in GaN thin films laterally overgrown on cone-shaped patterned sapphire substrates

Abstract

This study examines the influence of the growth mode on defect formation and strain relaxation in GaN thin films grown on cone-shaped patterned sapphire (CSPS) substrates by metal-organic chemical vapor deposition. A dramatic reduction in the luminescence dark spot density and a red-shifted excitonic emission were found for GaN on CSPS compared to GaN on planar sapphire substrates. The results also show that both the crystal quality and optical properties are improved in GaN on CSPS with a strong spatial correlation between the dark spots and local structural properties due to the induced-lateral overgrowth on the cone-shaped patterns.