ION-IMPLANTATION AND ENERGY DEPOSITION PROFILES IN THE STRAIGHT-AHEAD APPROXIMATION WITH REALISTIC POTENTIALS

The straight-ahead approximation to the Boltzmann equation is revisted and shown to be a viable and economical alternative to traditional, computationally demanding approaches for a class of ion transport problems. In conjunction with realistic potentials, and a fast and efficient numerical scheme, the model yields quite accurate profiles of implanted ions and of deposited energy for MeV P implantation in a Si substrate. Extensive results are presented for energetic heavy ion transport in multilayer media and mixtures. For 500 keV Bi ions incident on a Ge/Si bilayer implantation profiles are seen to be sensitive to the choice of interatomic potential. For a given potential, the effect of the disparate mass ratio on the energy spectrum is investigated as primary ions slow down across the interface from Ge into Si. Results are also presented for the partitioning of the primary ion (Bi and O) energy amongst the elements of the high-T(c) superconductor material YBa2Cu3O7.