Layer-Controlled\nChemical Vapor Deposition Growth\nof MoS₂ Vertical Heterostructures via van der Waals Epitaxy

Abstract

The\nfascinating semiconducting and optical properties of monolayer\nand few-layer transition metal dichalcogenides, as exemplified by\nMoS₂, have made them promising candidates for optoelectronic\napplications. Controllable growth of heterostructures based on these\nlayered materials is critical for their successful device applications.\nHere, we report a direct low temperature chemical vapor deposition\n(CVD) synthesis of MoS₂ monolayer/multilayer vertical heterostructures\nwith layer-controlled growth on a variety of layered materials (SnS₂, TaS₂, and graphene) via van der Waals epitaxy.\nThrough precise control of the partial pressures of the MoCl₅ and elemental sulfur precursors, reaction temperatures, and careful\ntracking of the ambient humidity, we have successfully and reproducibly\ngrown MoS₂ vertical heterostructures from 1 to 6 layers\nover a large area. The monolayer MoS₂ heterostructure was\nverified using cross-sectional high resolution transmission electron\nmicroscopy (HRTEM) while Raman and photoluminescence spectroscopy\nconfirmed the layer-controlled MoS₂ growth and heterostructure\nelectronic interactions. Raman, photoluminescence, and energy dispersive\nX-ray spectroscopy (EDS) mappings verified the uniform coverage of\nthe MoS₂ layers. This reaction provides an ideal method\nfor the scalable layer-controlled growth of transition metal dichalcogenide\nheterostructures via van der Waals epitaxy for a variety of optoelectronic\napplications.