Identification of the prime optical center inGaN:Eu3+

Abstract

We identify a dominant light-emitting center in ion-implanted $\text{GaN}:{\text{Eu}}^{3+}$ for which the lattice damage has been completely healed, according to x-ray diffraction and Rutherford backscattering spectrometry measurements, by high-temperature, high-pressure annealing. This center is likely to be the isolated substitutional ${\text{Eu}}_{\text{Ga}}$ defect. It lacks a ``subgap'' excitation band and therefore has no state in the GaN band gap, shows threefold splitting of its ${^{7}\text{F}}_{2}$ level, with two sublevels nearly degenerate, and exhibits a long, single-exponential luminescence decay. Competing luminescent centers of GaN:Eu involve this prime center with intrinsic lattice defects, one of which may also be responsible for the GaN yellow band.