The diffusion of boron in single crystal silicon has been modeled following a BF2 or boron implant in a polysilicon layer deposited on a single crystal silicon substrate. The effective concentration-dependent diffusivities of boron in single crystal have been extracted using Boltzmann-Matano analysis from the experimental boron diffusion profiles measured using secondary ion mass spectrometry. The effective boron diffusivities are found to be independent of the implant dose. A new analytical model for concentration-dependent boron diffusivities has been implemented in the PEPPER simulation program to accurately model the boron diffusion profiles in single crystal silicon for a polysilicon-on-single-crystal-silicon structure. The model has been verified for a wide range of furnace anneal conditions (800-950-degrees-C, from 30 min to 6 h), and implant conditions (BF2 doses varied from 5 x 10(15) to 2 x 10(16) cm-2 at 70 keV and boron dose of 5 x 10(15) cm-2 at 20 keV).