Synthesis and Characterization of Quaternary Monolayer Thick MoSe₂/SnSe/NbSe₂/SnSe Heterojunction Superlattices

Abstract

The synthesis of multiple-component heterostructures is conventionally accomplished through mechanical or chemical exfoliation, followed by physically stacking the layers together. Here, we report the synthesis, structure, and local composition of a three-component heterostructure (SnSe)1.16(MoSe2)1.06(SnSe)1.16(NbSe2)1, which was self-assembled at relatively low temperature (450 °C) from a designed precursor. XRD and STEM studies showed that the compound consisted of alternating layers of trigonal prismatic MoSe2 and NbSe2, interleaved with SnSe layers in a distorted rock salt structure. The new three-component ferecrystal is metallic with a factor of 3 higher conductivity than the (SnSe)1+δ(NbxMo1–x)Se2 ferecrystal alloy of the same composition (x ≈ 0.5). Comparison of the in-plane lattice parameters with the (SnSe)1+δ(NbxMo1−x)Se2 alloys allowed the extent of interdiffusion of the dichalcogenide constituents to be evaluated, yielding a stoichiometry of (SnSe)1.16([Mo0.9Nb0.1]Se2)1.06(SnSe)1.16([Nb0.9Mo0.1]Se2)1.