Lattice location and thermal stability of implanted nickel in silicon studied by on-line emission channeling

We have studied the lattice location of implanted nickel in silicon, for different doping types (n, n$^{+}$ and p$^{+}$). By means of on-line emission channeling, $^{65}$Ni was identified on three different sites of the diamond lattice: ideal substitutional sites, displaced bond-center towards substitutional sites (near-BC) and displaced tetrahedral interstitial towards anti-bonding sites (near-T). We suggest that the large majority of the observed lattice sites are not related to the isolated form of Ni but rather to its trapping into vacancy-related defects produced during the implantation. While near-BC sites are prominent after annealing up to 300-500°C, near-T sites are preferred after 500-600°C anneals. Long-range diffusion starts at 600-700°C. We show evidence of Ni diffusion towards the surface and its further trapping on near-T sites at the R$_p$/2 region, providing a clear picture of the microscopic mechanism of Ni gettering by vacancy-type defects. The high thermal stability of near-BC sites in n$^{+}$-type Si, and its importance for the understanding of P-diusion gettering are also discussed.