Growth and characterization of van der Waals heterostuctures formed by the topological insulator Bi₂Se₃ and the trivial insulator SnSe₂

The formation, structure and electronic properties of SnSe₂–Bi₂Se₃ van der Waals heterostructures were studied. Both heterostructures, SnSe₂ on Bi₂Se₃ and Bi₂Se₃ on SnSe₂, were grown epitaxially with high crystallinity and sharp interfaces. Their electron band structures are of trivial and topological insulators, respectively. The Dirac surface states of Bi₂Se₃ survive under the SnSe₂ overlayer. One triple layer of SnSe₂ was found to be an efficient spacer for separating a Bi₂Se₃ topological-insulator slab into two and creating the corresponding topological surface states.