Characterization of structural defects in semipolar GaN layers grown on patterned sapphire substrates

Abstract

We present the transmission electron microscopy characterization of GaN layers grown by metal–organic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HVPE) on patterned sapphire substrates (PSSs). We determined that the predominant I1-type basal stacking faults (BSFs) propagated toward the surface without an annihilation reaction, even when the layer thickness was increased by HVPE, whereas some threading dislocations were annihilated through their coalescence. It is revealed that BSFs were generated owing to the growth on the −c plane facet at the initial stage of MOVPE growth. One way to improve the crystalline quality is to use PSSs with wide terraces to expand the defect-free region.