Impurities–Si interstitials interaction in Si doped with B or Ga during ion irradiation

Abstract

Substitutional impurities (B, Ga) in Si experienced an off-lattice displacement during ion-irradiationusing a H+ or He+ beam at room temperature in random incidence. Samples were prepared by solid phase epitaxy(SPE) of pre-amorphized Si subsequently implanted with B and Ga at a concentration of about1 × 1020 at. cm−3 confined in a 300 nm thick surface region. The lattice location of impurities wasperformed by a channelling technique along different axes (, ) using the 11B(p,α)8Be reaction and standard RBS for B and Ga, respectively. The normalized channelling yieldχ of the impurity signal increases with the ion fluence, indicating a progressive off-latticedisplacement of the dopant during irradiation in random incidence, until it saturates atχF<1, suggesting a non-random displacement of the dopant. In particular, atsaturation the off-lattice displacement of B and Ga was investigated byangular scanning, revealing different positions for each dopant. This effecthas been related to the interaction of impurities with the Si self-interstitials(SiI) generated by the impinging beam in the doped region.