The effect of the ion mass upon ion beam-induced epitaxial crystallization was examined for C, Si, Ge, Ag and Au ions with energies of 1.5, 3.0 or 5.6MeV. The re-growth rates were normalized with respect to the number of displacements, or degree of energy deposition, in order to evaluate the contribution which defect generation made to crystal growth. The normalized re-growth rate increased, by a factor of 4, with decreasing ion mass from Au to C. However, the dose-rate dependence for 3MeV Au and Ag deviated from this mass-dependence curve at low dose rates; thus indicating that significant cascade-density effects (instantaneous dose-rate effects) coexisted with average dose-rate effects. This implied that the crystal growth rate was affected by defect interactions within individual cascades, as well as by defect interactions between different cascades. The activation energies which were measured for 4 types of ion at 3MeV were also mass-dependent, and ranged from 0.18 to 0.40eV. The results indicated that ion beam-induced epitaxial crystallization could not be characterized by a single activation energy. The data were compared with a number of models for ion beam-induced crystallization, and were found to be inconsistent with the process being controlled by a single defect-type. It was suggested that several rate-limiting defect processes might be involved and that the predominance of a single defect depended upon the ion mass (cascade density), average dose rate and temperature regime.

Mass Effects on Regrowth Rates and Activation Energies of Solid-Phase Epitaxy Induced by Ion Beams in Silicon A.Kinomura, J.S.Williams, K.Fujii: Physical Review B, 1999, 59[23], 15214-24