In this study an analytical approach is made to understand the mechanisms of boron-doping of Si using B 2 H 6 and SiH 4 in a H 2 atmosphere. A simple model, namely that every boron atom on the surface creates a two-dimensional nucleation site for Si, is used to explain the observed growth enhancement of Si at low temperatures and high B-doping levels. An excellent agreement between experimental data and the model is found. This result also gives deeper insights into the growth limiting steps of atmospheric pressure chemical vapour deposition of undoped Si.