Suppression of rare-earth implantation-induced damage in GaN

We have studied the damage induced by 80 keV Er implantation in epitaxial GaN/sapphire layers at room temperature and at 450 degreesC. The dopant distribution and lattice damage were investigated using Rutherford backscattering, channeling spectrometry and X-ray diffraction, whereas photoluminescence was used to probe the optical response. Random implantation results in substantial damage accumulation, which is difficult to recover during subsequent annealing. To reduce the ion-induced damage, we applied channeled implantation, i.e. directing the Er-beam along the nitride c-axis. Using this implantation geometry, a drastic decrease in the induced damage is observed. Channeled implantation generally results in green luminescence lines at room temperature, whereas no Er-related luminescence is observed after random implantation. (C) 2001 Elsevier Science B.V. All rights reserved.