EFFICIENT MOLECULAR-DYNAMICS SCHEME FOR THE CALCULATION OF DOPANT PROFILES DUE TO ION-IMPLANTATION

We present a highly efficient molecular dynamics scheme for calculatin g the concentration depth profile of dopants in ion irradiated materia ls. The scheme incorporates several methods for reducing the computati onal overhead, plus a rare event algorithm that allows statistically r eliable results to be obtained over a range of several orders of magni tude in the dopant concentration. We give examples of using this schem e for calculating concentration profiles of dopants in crystalline sil icon. Here we can predict the experimental profile over five orders of magnitude for both channeling and nonchanneling implants at energies up to hundreds of keV. The scheme has advantages over binary collision approximation (BCA) simulations, in that it does not rely on a large set of empirically fitted parameters. Although our scheme has a greate r computational overhead than the BCA, it is far superior in the low i on energy regime, where the BCA scheme becomes invalid.