Effective N-methyl-2-pyrrolidone wet cleaning for fabricating high-performance monolayer MoS₂ transistors

Two-dimensional semiconductors, such as MoS₂ are known to be highly susceptible to diverse molecular adsorbates on the surface during fabrication, which could adversely affect device performance. To ensure high device yield, uniformity and performance, the semiconductor industry has long employed wet chemical cleaning strategies to remove undesirable surface contaminations, adsorbates, and native oxides from the surface of Si wafers. A similarly effective surface cleaning technique for two-dimensional materials has not yet been fully developed. In this study, we propose a wet chemical cleaning strategy for MoS₂ by using N-methyl-2-pyrrolidone. The cleaning process not only preserves the intrinsic properties of monolayer MoS₂, but also significantly improves the performance of monolayer MoS₂ field-effect-transistors. Superior device on current of 12 μA·μm^–1 for a channel length of 400 nm, contact resistance of 15 kΩ·μm, field-effect mobility of 15.5 cm²·V^–1·s^–1, and the average on–off current ratio of 10⁸ were successfully demonstrated.