Lattice site location of optical centers in GaN:Eu light emitting diode material grown by organometallic vapor phase epitaxy

Eu-doped GaN was grown by organometallic vapor phase epitaxy at temperatures from 900 to $1100°C$⁠. Eu incorporation is influenced by temperature with the highest concentration found for growth at $1000°C$⁠. In all samples, Eu is incorporated entirely on substitutional Ga sites with a slight displacement which is highest $(∼0.2Å)$ in the sample grown at $900°C$ and mainly directed along the c-axis. The major optical $Eu3+$ centers are identical for in situ doped and ion-implanted samples after high temperature and pressure annealing. The dominant $Eu3+$ luminescence lines are attributed to isolated, substitutional Eu.