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

Herein,we propose a novel approach for area-selectivetunablegrowth of uniform monolayer or bilayer WS2 on dielectricsubstrates through in situ conversion of a predeposited W metal padto WO x initially and then to WS2 mono- and bilayers. Compared with the various transfer methods thathave been used previously for multilayer stacking, this direct-growthmethod has the advantages of producing cleaner interfaces and thecapability of growing tunable layers on target substrates, therebymaking it more suitable for manufacturing processes. The WS2 bilayer displayed uniform optical properties, with the atomic arrangementbetween layers having an AA stacking order that are supposed to havehigher mobility. We adopted these WS2 monolayers and bilayersin field-effect transistors. Accordingly, this approach for highlyarea-selective growth of transition metal dichalcogenide monolayersand bilayers with metal pads and their in situ conversion appearsto provide effective platforms for further device applications.