Scalable and Contamination-Free Selenium-Assisted Exfoliation of Transition Metal Dichalcogenides WSe2 and MoSe2

In two-dimensional (2D) materials research, exfoliating 2D transition metal dichalcogenides (TMDs) from their growth substrates for device fabrication remains a significant challenge. Current methods, such as those involving polymers, metals, or chemical etchants, suffer from limitations like contamination, defect introduction, and a lack of scalability. Here, we demonstrate a selenium capping-based exfoliation technique. Its advantage lies in its ability to enable the clean, contamination-free exfoliation and transfer of TMD films. We successfully exfoliated and transferred monolayer and multilayer TMD films, including WSe2 and MoSe2. The selenium capping layer not only enables seamless exfoliation but also protects the film from oxidation, as confirmed by X-ray photoelectron spectroscopy and Raman spectroscopy. This approach is versatile and applicable to a range of TMDs and thicknesses, paving the way for the high-quality, scalable integration of 2D materials into nanoelectronic devices.