Group III nitrides and other wide band-gap semiconductors like ZnO are very promising materials for application in optoelectronics. However, little is known about the recovery of lattice damage caused by ion implantation necessary to achieve lateral structuring. We use the PAC technique to study the behaviour of the Rare Earth isotope 172Lu(172Yb) after implantation. After annealing, a large fraction of the probes is found on unique lattice sites with axial symmetry and a low damping of the interaction frequency. In addition the corresponding electric field gradient is aligned along the ⟨0001⟩ axis. A substitutional incorporation of the Rare Earth on regular lattice sites is therefore probable.