The role of donor-acceptor pairs in the excitation of Eu-ions in GaN:Eu epitaxial layers

The nature of Eu incorporation and resulting luminescence efficiency in GaN has been extensively investigated. By performing a comparative study on GaN:Eu samples grown under a variety of controlled conditions, and using a variety of experimental techniques, the configuration of the majority site has been concluded to contain a nitrogen vacancy (VN). The nitrogen vacancy can appear in two symmetries, which has a profound impact on the luminescence and magnetic properties of the sample. The structure of the minority site has also been identified. We propose that, for both sites, the excitation efficiency of the red Eu emission is improved by the presence of donor-acceptor pairs in the close vicinity of the Eu. (C) 2014 AIP Publishing LLC.