Abstract Dopant incorporation during growth of films with δ-function like dopant profiles by Si molecular beam epitaxy is dominated by surface segregation at temperatures above 300°C. In this case the concentration should decay exponentially toward the surface. However, for sheet concentrations > 10 14 cm −2, we observe a plateau at about 10 20 cm −3, starting at the position of the intended δ-layer and extending toward the surface. Existing models are inconsistent with this observation. We describe a rate theory model for incorporation of Sb atoms into a Si film that predicts such a plateau, provided the Sb impurities are repelled from each other by means of a screened Coulomb interaction. The effects of temperature and growth rate on the Sb distribution predicted by our model are both consistent with the experiments.