Surface step edge-assisted monolayer epitaxy of α-antimonene on SnSe2 substrate

We demonstrate a strategy of van der Waals (vdW) epitaxy assisted by surface step edges. Different from the usual vdW epitaxy where the growth is initiated by the vdW interactions with the substrate, the step edge-assisted epitaxy is most likely initiated by the formation of a strong valence bond at the periphery of surface step edges, thus allowing for the growth of strained vdW monolayers. With this strategy, we have successfully grown the α-antimonene monolayer with a puckered honeycomb lattice on the SnSe2 substrate with a high density of surface step edges, thus forming a horizontal heterostructure. This study paves a way toward tuning the morphology and properties of epitaxial vdW materials via a strong valence bond at the boundary between the epilayer and substrate.