Up to 30 nm thick Ge layers were grown on Si(100) by using Sb as a surfactant and were investigated by reflection high‐energy electron diffraction, x‐ray photoelectron spectroscopy,secondary ion mass spectroscopy,transmission electron microscopy, and confocal laserscan microscopy. The introduction of a surfactant alters the growth mode drastically from a three‐dimensional clustering mechanism to a two‐dimensional layer‐by‐layer growth. Smooth and strained Ge layers, with a thickness much larger then the critical thickness for commensurate growth, are achievable. The antimony monolayer mainly segregates on top of the growngermanium layer.