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

Abstract

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 FeGeγ (γ∼1.52) on Si substrates. In the SAE, the intermetallic compound FeGeγ film is epitaxially grown by annealing after deposition of amorphous FeGeγ film on FeGeγ nanoseeds. The interfaces between the nanoseeds and the films promote the epitaxial growth of the intermetallic compound FeGeγ. Furthermore, the composition ratio controls the orientation of the one-dimensional Ge helical ladders and Fe helices in the Nowotny chimney-ladder FeGeγ 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.