In order to explore more completely the role of plasma ions in the epitaxial growth of silicon thin films by remote plasma chemical vapor deposition (RPCVD), absolute cross-sections for the removal of hydrogen from the 2H::Si(100) surface by 100-200eV Ar + and He + ions have been measured. The cross-sections are of the order of 1x10 - 1 7 cm 2 , with Ar + being more effective than He + in the sputter removal of surface hydrogen. Recoil implantation removal of surface hydrogen could not be measured directly in these experiments, but was estimated by Monte Carlo modeling. The modeling suggests that recoil implantation removal is of increasing importance at lower ion energies, and is more important for Ar + bombardment than for He + . These results support the hypothesis that the generation of active sites through the removal of hydrogen from the passivated surface is an important step in the growth mechanism for RPCVD silicon epitaxy. They also explain the greater efficacy of Ar + plasmas in RPCVD.