Substitutional impurities (B, Ga) in Si experienced an off-lattice displacement during ion-irradiation using a H+ or He+ beam at room temperature in random incidence. Samples were prepared by solid-phase epitaxy of pre-amorphized Si subsequently implanted with B and Ga at a concentration of about 1020/cm3 confined in a 300nm thick surface region. The lattice location of impurities was performed by a channelling technique along different axes (<100>, <110>) using the 11B(p,α)8Be reaction and standard Rutherford back-scattering for B and Ga, respectively. The normalized channelling yield χ of the impurity signal increased with the ion fluence, indicating a progressive off-lattice displacement of the dopant during irradiation in random incidence, until it saturates at χF<1, suggesting a non-random displacement of the dopant. In particular, at saturation the off-lattice displacement of B and Ga was investigated by angular scanning, revealing different positions for each dopant. This effect was related to the interaction of impurities with the Si self-interstitials (SiI) generated by the impinging beam in the doped region.

Impurities–Si Interstitials Interaction in Si Doped with B or Ga during Ion Irradiation. L.Romano, A.M.Piro, M.G.Grimaldi, E.Rimini: Journal of Physics - Condensed Matter, 2005, 17[22], S2279-84