Critical angles and low-energy limits to ion channeling in silicon

Publisher Website
Google Scholar
Abstract
Channeling theory is reviewed and some improvements are presented. Several models for the calculation of critical approach distances, critical angles, and minimum energies for channeling are compared. While the influence of the choice of the interatomic potential is small, existing models of the critical approach distance yield rather different results particularly in the case of planar channeling. An improved model is proposed based on binary collision simulations. A low-energy limit to ion channeling along a given axis or plane is defined by equating the critical approach distance with the channel radius. Minimum energies for channeling and critical angles as a function of energy are presented for B, P, and As in Si along the major channels. In the case of B in Si from these data channeling maps are constructed and compared with channeling maps obtained from binary collision simulations. The predicted minimum energies for channeling are shown to agree well with a large number of experimental data obtained by SIMS, thermal wave, and backscattering yield measurements. Finally, the relevance of the critical angles and of calculated channeled fractions to ion implantation is discussed.