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 WOx 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.