On the Nature of Eu in Eu-Doped GaN

Abstract

Using scanning transmission electron microscope high-angle annular dark-field imaging, we have investigated the Eu-rich region formed by high-energy implantation of Eu+ ions into GaN and annealing at 1300 degrees C. In conjunction With multi-slice calculations, we have used the higher-than-average intensities of atomic columns to identify candidate Eu-containing strings and calculate the visibility of these strings. These candidate strings show a bimodal distribution; the higher mode agreeing well with the visibilities suggested by the multi-slice calculations. From this, we find that the Eu atoms are predominantly isolated and do not form Eu-clusters after annealing.