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