Enhanced diffusion of B is observed during the growth of ion bombarded epitaxial layers by Si molecular beam epitaxy. Ion‐assisted methods are generally required for high levels ofn‐type doping, and we find that the damage caused by the low‐level ion bombardment is responsible for the enhanced diffusion of B. Furthermore, the concentration profiles of as‐grown and post‐growth annealed samples show that the diffusion is a transient effect that occurs at the growth temperature of 600–700 °C. Simulation of the diffusion process demonstrates that nearly all of the B is participating in the diffusion and that the built‐in electric field at thep‐njunction leads to a further smearing of the B profile.