Facilitating uniform large-scale MoS₂, WS₂ monolayers and their heterostructures through van der Waals Epitaxy

Abstract

The fabrication process for the uniform large-scale MoS₂, WS₂ transition metal
dichalcogenides (TMDCs) monolayers and their heterostructures has been developed by Van der Waals epitaxy (VdWE) through the reaction of MoCl₅ or WCl6 precursors and the reactive gas H₂S to form MoS₂ or WS₂ monolayers, respectively. The heterostructures of MoS₂/WS₂ or WS₂/MoS₂ can be easily achieved by changing the precursor from WCl₆ to MoCl₅ once the WS₂ monolayer has been fabricated or switching the precursor from MoCl5 to WCl₆ after the MoS₂ monolayer has been deposited on the substrate.
These VdWE-grown MoS₂, WS₂ monolayers and their heterostructures have been successfully deposited on Si wafer with 300 nm SiO₂ coating (300 nm SiO₂/Si), quartz glass, fused silica and sapphire substrates using the protocol we have developed. We have characterized these TMDCs materials with a range of tools/techniques including scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), micro-Raman, photoluminescence (PL), atomic force microscopy (AFM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX) and selected area electron diffraction (SAED). The band alignment and large-scale uniformity of MoS₂/WS₂ heterostructures have also been evaluated with PL spectroscopy.
This process and resulting large-scale MoS₂, WS₂ monolayers and their heterostructures have demonstrated promising solutions for the applications in next generation nanoelectronics, nanophotonics and quantum technology.

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Identifiers

ORCID for Kevin Chung-Che Huang: orcid.org/0000-0003-3471-2463

ORCID for Tomas Polcar: orcid.org/0000-0002-0863-6287

ORCID for Daniel W. Hewak: orcid.org/0000-0002-2093-5773

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