Rapid and Large-Scale Quality Assessment of Two-Dimensional MoS₂ Using Sulfur Particles with Optical Visualization

The efficient nondestructive assessment of quality and homogeneity for two-dimensional (2D) MoS₂ is critically important to advance their practical applications. Here, we presented a rapid and large-area assessment method for visually evaluating the quality and uniformity of chemical vapor deposition (CVD)-grown MoS₂ monolayers simply with conventional optical microscopes. This was achieved through one-pot adsorbing abundant sulfur particles selectively onto as-grown poorer-quality MoS₂ monolayers in a CVD system without any additional treatment. We further revealed that this favorable adsorption of sulfur particles on MoS₂ originated from their intrinsic higher-density sulfur vacancies. Based on unadsorbed MoS₂ monolayers, superior performance field effect transistors with a mobility of ∼49 cm² V^-1 s^-1 were constructed. Importantly, the assessment approach was noninvasive due to the all-vapor-phase and moderate adsorption-desorption process. Our work offers a new route for the performance and yield optimization of devices by quality assessment of 2D semiconductors prior to device fabrication.