Seed-assisted epitaxy of intermetallic compounds with interface-determined orientation: Incommensurate Nowotny chimney-ladder FeGe epitaxial film

Epitaxial growth of functional thin films on Si substrates is attracting great attention in various electronic fields. However, the conventional epitaxial growth methods cannot be applied to all materials; for example, intermetallic materials are often difficult to epitaxially grow due to the atomic diffusion causing segregation or deviation of target stoichiometry. In this work, seed-assisted epitaxy (SAE) is presented as a technique to enable the epitaxial growth of intermetallic materials such as incommensurate Nowotny chimney-ladder FeGe _γ ( γ ∼1.52) on Si substrates. In the SAE, the intermetallic compound FeGe _γ film is epitaxially grown by annealing after deposition of amorphous FeGe _γ film on FeGe _γ nanoseeds. The interfaces between the nanoseeds and the films promote the epitaxial growth of the intermetallic compound FeGe _γ. Furthermore, the composition ratio controls the orientation of the one-dimensional Ge helical ladders and Fe helices in the Nowotny chimney-ladder FeGe _γ grown from the nanoseed interface. This result proposes the SAE method as a powerful tool for epitaxial growth of various functional intermetallic materials on Si substrates.