Optimization of Defects in Large-Area Synthetic MoS2 Thin Films by CS2 Treatment for Switching and Sensing Devices

The large-scale two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted great attention in the fields of high-performance switching and sensing devices, and various synthesis approaches have been proposed and applied for effective device integration and circuit-level application. However, such synthetic TMDC thin films have intrinsic limitations due to a mass of sulfur vacancies after a series of high-temperature processing, which has significantly restricted further implementation in high-performance nanoelectronics applications. Here, we proposed a method of optimizing the defects of sulfur vacancies by using CS2 treatment on the large-area MoS2 film synthesized by atomic layer deposition (ALD). Sulfur atoms introduced by CS2 decomposition at high temperature fill the vacancies in MoS2, generating a more robust crystal lattice structure. The involvement of CS2 treatment has significantly improved the stoichiometry and crystallinity which is confirmed by X-ray photoelectron spectroscopy and Raman characterizations. The top-gate MoS2 transistors fabricated based on the CS2-treated MoS2 film have shown enhanced electrical performance including larger on/off current ratio and more decent carrier mobility as compared to the devices built on the nontreated film. Our results can pave a promising pathway for the optimization of the large-area synthetic TMDC thin films in future switching and sensing devices toward higher level system and circuit applications.