Using three-source molecular beam epitaxy, we demonstrate the direct heteroepitaxial growth of the direct semiconductorCuInS2on silicon (001) substrates. The pretreatment of the silicon wafers includes a high-temperature exposure to the sulphur beam which leads to an ideal(1×1)sulphur-terminated surface defining the starting condition for successful epitaxy. All stages of the growth process were controlledin situusing Auger electron spectroscopy and low energy electron diffraction. Furthermore, the epitaxial layers were characterized by means of x-ray diffraction methods and by transmission electron microscopy. It is shown that theCuInS2epilayers grow with a tetragonal structure which is clearly distinct from chalcopyrite. ©1998 American Institute of Physics.