PVA-Mediated Transfer of MoS2 and Au Electrodes: A Lithography-Free Route to Ultraclean van der Waals Interfaces for...

Scalable 2D semiconductor device integration is persistently hindered by polymer residues, wrinkles, and interfacial voids introduced during transfer, as well as by surface damage incurred during photolithographic contact fabrication, collectively degrading metal/semiconductor interfaces and limiting device reproducibility. Here, we report an aqueous poly(vinyl alcohol) (PVA) platform that resolves both challenges within a single workflow. By incorporating a controlled fraction of isopropyl alcohol (IPA) into the PVA solution, wetting conformity is improved and interfacial void trapping during film delamination is suppressed, yielding wrinkle-free, optically uniform monolayer MoS2 with preserved surface morphology. The same platform enables lithography-free integration of prepatterned Au electrodes onto MoS2 via van der Waals contact transfer, avoiding direct photolithographic exposure and metal-deposition damage to the MoS2 channel/contact interface. We further demonstrate that PVA treatment provides a low-temperature route to refresh aged MoS2 surfaces by removing adventitious adsorbates and reducing nanoscale roughness. Critically, optimal photodetector performance is achieved only when lithography-free contacts are paired with a sufficiently clean semiconductor channel, establishing a quantitative link between transfer quality and contact behavior. PVA-transferred MoS2 devices with transferred Au contacts exhibit carrier mobility of 6.27 ± 2.74 cm2 V-1 s-1 and responsivity and detectivity exceeding conventional PMMA-based devices by over two orders of magnitude under weak illumination.