Implantation angle dependence of ion irradiation damage in GaN

We use molecular dynamics (MD) simulations to study the effect of the implantation angle on the damage produced during ion beam irradiation of GaN. We bombard 5 keV Er ions at perfect wurtzite GaN with incident angles of 0°–22° angle against the [0 0 0 1] crystal axis. The simulations reproduce the angular dependence of the damage observed in the experiments. Two main reasons for the experimentally observed suppression in damage production are found. One is the decreased total damage production for small angles and another is the smaller fraction of clustered defects formed during channeling implantations. Large damage clusters are found to form near the surface. The surface damage peak is stronger for large angle bombardment.