We have correlated luminescence studies of epitaxially laterally overgrown GaN with microstructure and local carrier concentration measurements. We have found that the luminescence characteristics of the coherently grown regions are considerably different from those of the sidewall facets. We find that these differences are related to the growth-front and not the dislocation density. The differences appears to be due to a variation in the incorporation of Ga vacancies for different facets. The ELO GaN (ELOG) structures were grown using metalorganic chemical vapor deposition, with a parallel stripe pattern of SiO2 mask along (1100) direction.