Ion beam enhanced diffusion of B during Si molecular beam epitaxy

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 of n-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 the p-n junction leads to a further smearing of the B profile.