Beam-induced annealing of defects in silicon after light-ion implantation at 30 K

The channeling technique has been applied to investigate the damage created by implantation at 30 K with low-energy deuterium or helium in Si. It is demonstrated that irradiation at 30 K with a 750-keV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ beam induces a dramatic annealing of lattice defects. The annealing is found to be connected with the electronic part of the stopping power, and it may be explained in terms of ionization-induced migration of self-interstitials and vacancies. The experiments were carried out on the as-implanted sample and after isochronal annealing at various temperatures. Annealing stages observed at 110 and 190 K are interpreted in terms of vacancy and interstitial migration, respectively. From the channeling analysis, the major part of the Si atoms participating in the beam-induced reordering is found to be displaced on the average by about 0.25 Å from a lattice site. The displacements are interpreted as lattice relaxations around vacancy- and interstitial-type defects. There is a small interstitial component which may be ascribed to self-interstitials in a dumbbell configuration. The orientation can be in a 〈110〉 or 〈111〉 direction but not in a 〈100〉 direction.