All-dry fabrication of hBN-encapsulated devices with high-quality CVD-grown transition metal dichalcogenide flakes

Two-dimensional (2D) semiconductors, including transition metal dichalcogenides (TMDs), have provided a fascinating opportunity to explore novel optical and electric properties at the two-dimensional limit. For this purpose, high-quality devices are indispensable to address their intrinsic properties, and TMDs prepared with the mechanical exfoliation method have been used. Here, we report all-dry fabrication of hexagonal Boron Nitride (hBN) encapsulated devices with CVD-grown monolayer tungsten disulfide (WS₂). Using pre-patterned hBN fabricated with reactive ion etching, we have successfully picked up the CVD-grown TMDs directly from the substrate. Fabricated field effect transistor (FET) devices have shown FET mobility of ca. 40 cm²/Vs at room temperature. Considering the advantages of CVD-grown TMDs, large-area monolayer flakes is possible, the present method should contribute to further exploration of basic properties of TMDs. In this presentation, the details of device fabrication and electric transport of hBN-encapsulated devices will be explained.