Solid-phase growth of β-FeSi₂ on Si substrates with different crystal orientations

Orientation dependent solid-phase growth of β-FeSi₂ thin films on (100), (110), and (111) Si substrates has been investigated by using a-Fe(thickness: 20 nm)/c-Si stacked structures. XRD measurements suggested that the substrate orientation dependence of the formation rate of β-FeSi₂ was as follows: (100) > (111) > (110). This dependence can be explained on the basis of the lattice mismatch between β-FeSi₂ and Si substrates, i.e., the lattice mismatch between β-FeSi₂ (100) and Si (100), β-FeSi₂ (110) or (101) and Si (111), and β-FeSi₂ (010) or (001) and Si (110) are 1.4-2.0%, 5.3-5.5%, and 9.2%, respectively. The substrate orientation dependence of solid-phase growth becomes relatively remarkable for very thin films.