Ion implanted dopants in GaN and AlN: Lattice sites, annealing behavior, and defect recovery

The recovery of structural defects in gallium nitride (GaN) and aluminum nitride (AlN) after implantation of ${}^{\mathrm{111}}{\mathrm{In}}^{\mathrm{+}}$ and ${}^{\mathrm{89}}{\mathrm{Sr}}^{\mathrm{+}}$ in the dose range (0.1–3) ${10}^{13}$ ${\mathrm{cm}}^{\text{−2}}$ and ion energies of 60–400 keV has been investigated as a function of annealing temperature with emission channeling (EC) and perturbed γγ angular correlation spectroscopy. The implanted In and Sr atoms occupied substitutional sites in heavily perturbed surroundings of point defects after room temperature implantation. No amorphization of the lattice structure was observed. The point defects could be partly removed after annealing to 1473 K for 10–30 min. Lattice site occupation of implanted light alkalis, ${}^{\mathrm{24}}{\mathrm{Na}}^{\mathrm{+}}$ in GaN and AlN as well as ${}^{\mathrm{8}}{\mathrm{Li}}^{\mathrm{+}}$ in AlN, were also determined by EC as a function of implantation and annealing temperature. These atoms occupied mainly interstitial sites at room temperature. Lithium diffusion and the occupation of substitutional sites was observed in GaN and AlN at implantation temperatures above 700 K. A lattice site change was also observed for sodium in AlN, but not in GaN after annealing to 1073 K for 10 min.