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 (∼0.2 Å) in the sample grown at 900 °C and mainly directed along the c-axis. The major optical Eu 3+ centers are identical for in situdoped and ion-implanted samples after high temperature and pressure annealing. The dominant Eu 3+ luminescence lines are attributed to isolated, substitutional Eu.