Area-Selective Growth of Two-Dimensional Mono- And Bilayer WS₂ for Field Effect Transistors

Herein, we propose a novel approach for area-selective tunable growth of uniform monolayer or bilayer WS₂ on dielectric substrates through in situ conversion of a predeposited W metal pad to WO_x initially and then to WS₂ mono- and bilayers. Compared with the various transfer methods that have been used previously for multilayer stacking, this direct-growth method has the advantages of producing cleaner interfaces and the capability of growing tunable layers on target substrates, thereby making it more suitable for manufacturing processes. The WS₂ bilayer displayed uniform optical properties, with the atomic arrangement between layers having an AA stacking order that are supposed to have higher mobility. We adopted these WS₂ monolayers and bilayers in field-effect transistors. Accordingly, this approach for highly area-selective growth of transition metal dichalcogenide monolayers and bilayers with metal pads and their in situ conversion appears to provide effective platforms for further device applications.