Near band edge and defect emissions from epitaxial lateral overgrown a-plane GaN with different stripe orientations

Epitaxial lateral overgrowth (ELOG) of a-plane GaN on r-plane sapphire with stripe orientations parallel to [0 0 0 1], [011̲1], and [011̲0] has been investigated. The emission from ELOG stripes with different orientations and from different growth facets has been compared by spectrally and spatially resolved cathodoluminescence and by temperature-dependent photoluminescence measurements. A reduction in the nonradiative recombination rate by the ELOG process is clearly observed. For all stripe orientations the ELOG wing regions exhibit increased radiative emission intensities compared to the window areas, indicating a reduced dislocation density in the overgrown areas. The highest increase of the near band edge (NBE) emission is observed in the wing regions for stripes parallel to [011̲0]. In this region, the density of basal plane stacking faults (BSFs) is also reduced. NBE emission is detected up to temperatures of 250 K.