We have compared ion channeling results with molecular dynamics simulations to investigate low‐temperature molecular beam homoepitaxy on silicon. We report the temperature dependence, rate dependence, and thickness dependence of films grown on Si(111). For 350 A˚ films, a transition to good crystalline quality is seen in ion channeling at growth temperatures of ≊400 °C; this is compared to ≊100 °C for (100) epitaxy. The evolution of surface microstructure leading to breakdown of epitaxial growth at low temperatures is discussed.