Formation of twins during epitaxial growth of -iron films on silicon (111)

Since the initial report on the epitaxial growth of -Fe films on hydrogen-terminated Si(111) surfaces at 300 K, two in-plane orientation relationships, twinned and aligned epitaxy, have been suggested. In this paper, the epitaxial growth of Fe on Si(111) is further examined in detail by x-ray-diffraction -2 scans, x-ray-diffraction scans, transmission electron microscopy, and reflection high-energy electron diffraction. Twinned epitaxy at the Fe/Si interface is established, i.e., (111)-Fe(111)Si and [110]-Fe[110]Si. As the film thickness increases, the formation of twins in the epitaxial -Fe films is observed. The apparent aligned epitaxy is the result of twinning in the -Fe film. The formation of twins in the epitaxial -Fe film is attributed to the limited mobility at 300 K. The dominance of twinned epitaxy at the interface suggests that the influence of the second-nearest-neighbor interaction between Fe and Si atoms near the interface is important.