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

摘要

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) which was self-assembled at relatively low temperature (450 degrees 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+delta)(NbxMo1-x)Se-2 ferecrystal alloy of the same composition (x approximate to 0.5). Comparison of the in-plane lattice parameters with the (SnSe)(1+delta)(NbxMo1-x)Se-2 alloys allowed the extent of interdiffusion of the dichalcogenide constituents to be evaluated, yielding a stoichiometry of (SnSe)(1.16)([Mo0.9Nb0.1]-Se-2)(1.06)(SnSe)(1.06)([Nb0.9Mo0.1]Se-2)(1).