Transition-metal dichalcogenides (TMDs) show great potential for next-generation semiconductor due to its atomic level thickness, tunable band gap and high carrier mobility. However, high-quality monolayer MoS 2 (ML-MoS 2 ) films require stringent growth conditions during preparation. Here, we report a face-to-face metal precursor supply approach during chemical vapor deposition (CVD) to batch production of uniform ML-MoS 2 films. Mo foils provide a stable concentration of metal precursors leading to uniform film generation with low nucleation. Comprehensive characterization techniques, including spectroscopic, surface topography and atomic scale analysis confirm the centimeter-scale homogeneity and high crystallographic quality of the monolayer films. Back-gate field effect transistors (FET) fabricated by ML-MoS 2 exhibit excellent electrical performance. This methodology provides a pathway for the growth of TMDs, which should promote their applications in high-performance electronics or other fields.
Manipulation of wavefront lies at the core of next-generation information technologies. Compared to metal and dielectric metasurfaces, atomic 2D materials exhibit excellent prospects toward fulfilling ultra-thin thickness requirements in flat optics in wavefront shaping, with thickness much smaller than those of traditional bulky devices. However, phase manipulation by light propagating through atomic 2D materials is suppressed due to its sub-nanometer thickness. Here, an approach is reported to realize reflection phase singularities by establishing a zero-reflection point in a monolayer MoS 2 -based multilayer system, which broadens topological study beyond polarization singularity. This is achieved through the creation of a multilayer Fabry-Perot-type interference, and a pronounced phase change in the reflected light is realized due to the high absorption of monolayer MoS 2 in the studied wavelength range. As an application, a rapid, sensitive, and label-free detection of SARS-CoV-2 (2019-nCov) antigen is demonstrated with a detection limit of 10 −12 M L −1 (62 pg ml −1 ) by using monolayer MoS 2 based optical biosensor. In addition to offering a comprehensive study in phase singularity, efficient wavefront engineering based on the reflective system using materials is presented with atomic thickness which may greatly simplify optical architecture in flat optics, and promote its development toward compactness and integrated functions.
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