Luminescence Properties of Eu-Doped GaN Grown on GaN Substrate

We report a study on Eu the luminescence properties of Eu-doped GaN (GaN:Eu) grown on a GaN substrate by organometallic vapor phase epitaxy (OMVPE). Thermal quenching of the Eu luminescence was suppressed using the GaN substrate, which is due to the preferential formation of a Eu luminescent site with a local structure with high symmetry. The preferential formation of this luminescent site was supported by the observation of strong near-band-edge emission. The strong near band-edge emission occurred as a result of suppressed formation of the dominant Eu luminescent site in GaN:Eu on a sapphire substrate, which is known to be coupled with a defect and to have a large capture cross section of photogenerated carriers.