Lattice location of implanted tellurium in GaN heteroepitaxial films

The lattice site of implanted tellurium in gallium nitride heteroepitaxial films grown on sapphire substrates has been studied. GaN samples were implanted with 400 keV 130Te ions at 300 °C. The ion dose was 1.5×1015 cm-2. The samples were analysed with Rutherford backscattering spectrometry channelling using 2.0 MeV 4He ions. The maximum Te concentration was 0.2 at.%. Based on measured channelling angular scans for Ga and Te along the 0001 and 101 axial directions, analysed by comparison with Monte Carlo simulations, it was concluded that in the as-implanted sample about 70% of Te atoms were on the Ga atom lattice sites, slightly displaced. The measured 101 scan showed no evidence of substitutional Te on N lattice site. The post-implantation annealing at 900 °C was found to decrease the substitutional fraction of Te while little recovery of the host lattice was observed. This indicates an interaction process between Te atoms and implantation-induced lattice defects. No migration of Te during annealing at 900 °C was observed. In addition, the effect of misfit dislocations in the host lattice on the channelling yield was visible in the 101 angular scan measured at a 47° tilt angle.}