High-Fidelity Transfer\nof 2D Semiconductors and Electrodes\nfor van der Waals Devices

As traditional silicon-based materials\nalmost reach their\nlimits\nin the post-Moore era, two-dimensional (2D) transition metal dichalcogenides\n(TMDCs) have been regarded as next-generation semiconductors for high-performance\nelectrical and optical devices. Chemical vapor deposition (CVD) is\na widely used technique for preparing large-area and high-quality\nTMDCs. Yet, it suffers from the challenge of transfer due to the strong\ninteraction between 2D materials and substrates. The traditional PMMA-assisted\nwet etching method tends to induce damage, wrinkles, and inevitable\npolymer residues. In this work, we propose an etch-free and clean\ntransfer method via a water intercalation strategy for TMDCs, ensuring\na high-fidelity, wrinkle-free, and crack-free transfer with negligible\nresidues. Furthermore, metal electrodes can also be transferred via\nthis method and back-gate field-effect transistors (FETs) based on\nCVD-grown monolayer WSe<sub>2</sub> with van der Waals (vdW) metal/semiconductor\ncontacts are fabricated. Compared to the PMMA-assisted transfer method\n(∼1.2 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> hole mobility with ∼2 × 10<sup>6</sup> ON/OFF ratio),\nour high-fidelity transfer method significantly enhances the electrical\nperformance of WSe<sub>2</sub> FET over one order of magnitude, achieving\na hole mobility of ∼43 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> and a high ON/OFF ratio of ∼5 ×\n10<sup>7</sup> in air at room temperature.