Lattice location of implanted tellurium in GaN heteroepitaxial films

Abstract

The lattice site of implanted tellurium in gallium nitrideheteroepitaxial films grown on sapphire substrates has been studied. GaNsamples were implanted with 400 keV 130Te ions at 300 °C. Theion dose was 1.5×1015 cm-2. The samples were analysedwith Rutherford backscattering spectrometry channelling using 2.0 MeV4He ions. The maximum Te concentration was 0.2 at.%. Based onmeasured channelling angular scans for Ga and Te along the ⟨0001⟩ and ⟨101̅1⟩ axial directions,analysed by comparison with Monte Carlo simulations, it was concluded thatin the as-implanted sample about 70% of Te atoms were on the Ga atomlattice sites, slightly displaced. The measured ⟨101̅1⟩ scan showed no evidence of substitutional Te on Nlattice site. The post-implantation annealing at 900 °C was foundto decrease the substitutional fraction of Te while little recovery of thehost lattice was observed. This indicates an interaction process betweenTe atoms and implantation-induced lattice defects. No migration of Teduring annealing at 900 °C was observed. In addition, the effect ofmisfit dislocations in the host lattice on the channelling yield wasvisible in the ⟨101̅1⟩ angular scan measured at a47° tilt angle.}\\fnm{3}{Present address: Vaisala Oyj, FIN-00421 Helsinki, Finland.