MBE growth of β-FeSi₂ epitaxial film on hydrogen terminated Si (1 1 1) substrate

β-FeSi₂ single crystal epitaxial films were successfully grown on hydrogen terminated Si (1 1 1) substrates by using solid source molecular beam epitaxy (SS-MBE). The β-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 °C. To study the effect of Fe/Si ratio on the film quality, a series of epilayers were grown at 580 °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 β-FeSi₂ epitaxial films at 580 °C, while the metallic ε-FeSi phase grew predominantly at 480 °C. The observations of transmission electron microscope (TEM) and reflective high-energy electron diffraction (RHEED) verified the epitaxial growth of β-FeSi₂ films on Si (1 1 1).