High purity Al films were epitaxially grown on Si substrares by gas-source metalorganic molecular-beam epitaxy method using dimethylethylamine-alane as a source gas. Crystalline orientation of the Al films on the Si(1 0 0) substrates was determined as Al(1 1 0) Si(1 0 0). The reflection high-energy electron diffraction patterns from the Al film grown at 500°C showed streaky patterns. The growth rate increased with increase of the growth temperature, and the activation energy of the growth rate was 0.28 eV, which was smaller than those of other alkyl Al sources. The carbon incorporation in the grown Al film was smaller compared with those grown by other alkyl aluminum.