Heteroepitaxial cubic SiC films were grown on (001) Si substrates at 900 to 980 degrees C using 1,3-disilabutane (H3SiCH2SiH2CH3) as a single molecular precursor under high vacuum conditions (5.0 to 8.0 x 10(-6) Torr). A carbonized buffer layer, grown in situ by gas source molecular beam epitaxy (GSMBE) of propane (C3H8) was employed to minimize the effect of lattice mismatch between the Si substrate and the SiC overlayer. The crystalline structure, chemical composition, and thickness of the deposited films were investigated by in situ reflection high-energy diffraction, x-ray diffraction, Rutherford back scattering, Auger electron spectroscopy and transmission electron microscopy. The results show that high quality epitaxial 3C-SiC films with correct stoichiometry can be deposited on Si in this temperature range. The single precursor 1,3-disilabutane has been found suitable for the epitaxial growth of cubic SiC on (001) Si substrates.