Channeling studies of ion-implanted silicon

Abstract

The channeling effect has been used to study the lattice location of Sb, Bi and Pb implanted into Si. Angular scans through the ⟨111⟩, ⟨110⟩ and ⟨100⟩ axes show that the channeling dips obtained in 1 MeV He ion scattering measurements are significantly narrower for the impurities than for the Si host lattice. Annealing of Sb implanted samples at 900°C results in a broadening of the Sb dip but not to the full Si width. Measurements on diffused Sb samples give wider Sb dips than for implanted Sb. Calculations of channeling angular distributions using the average potential model, imply that the smaller widths of the impurity dips can be caused by a small equilibrium displacement of the impurity atoms from lattice sites. Preliminary measurements on B implanted Si crystals annealed at 950°C for 30 minutes, indicate that the dip width obtained from the ₁₁B(p, α)₈Be reaction at 670 keV does not differ significantly from that obtained from 670 keV proton scattering off Si.