beta-FeSi2 single crystal epitaxial films were successfully grown on hydrogen terminated Si (111) substrates by using solid source molecular beam epitaxy (SS-MBE). The beta-FeSi2 epitaxial film with thickness of 180 nm was grown without template-layer or post-growth annealing. By analyzing X-ray diffraction (XRD) patterns and the corresponding scanning electron microscopy (SEM) images, the optimal growth temperature was established to be 580 degrees C. To study the effect of Fe/Si ratio on the film quality, a series of epilayers were grown at 580 degrees C with various Fe/Si ratios from 2 to 0.4. The stoichiometric Fe/Si flux ratio of 0.5 was confirmed to be an essential condition to grow single crystalline beta-FeSi2 epitaxial films at 580 degrees C, while the metallic epsilon-FeSi phase grew predominantly at 480 degrees C. The observations of transmission electron microscope (TEM) and reflective high-energy electron diffraction (RHEED) verified the epitaxial growth of beta-FeSi2 films on Si (111). (c) 2005 Elsevier B.V. All rights reserved.