In this work, we study previously published Pearson models in amorphous silicon and present an improved Pearson IV model of ion implantation as a function of implant energy and crystal orientation for use in crystalline silicon. The first 4 moments of the Pearson IV distribution have been extracted from impurity profiles obtained from the Binary Collision Approximation (BCA) code, Crystal TRIM for a wide energy range 0.1-300 keV at varying tilts and rotations. By comparisons with experimental data, we show that certain amounts of channelling always occur in crystalline targets and the analytical Pearson technique should be replaced by a more robust method. We propose an alternative model based on sampling calibration of profiles and present implant tables that has been assimilated in the process simulator DIOS. Two-dimensional impurity profiles can be subsequently generated from these one-dimensional profiles when the lateral standard deviation is specified. (c) 2005 Elsevier Ltd. All rights reserved.