High-Luminescence and Submillimeter-Scale MoS2 Monolayer Growth Using Combinational Phase Precursors via Chemical Vapor Deposition

We successfully synthesize high-luminescence and submillimeter-scale monolayers of molybdenum disulfide (MoS2) employing a combinational phase precursor via a chemical vapor deposition (CVD) approach. First, sodium nitrate catalyst is demonstrated to assist the reaction equilibrium of a solid precursor CVD process, leading to an increased density and size of MoS2 monolayer flakes (∼120 μm). However, the monolayers' photoluminescence intensity is significantly reduced due to the presence of excess residues. A suspension solution-based precursor is also tested using the optimized temperature, pressure, and catalyst from the solid precursor case, and it is found to also give a high density of uniform triangles with an average size of ∼80 μm. Finally, combining both precursor phases (combinational phase precursor) yields the largest monolayer flakes with an average size of ∼200 μm and the highest luminescence, with photoluminescence intensities being 1 order of magnitude higher than that of a standard mechanical exfoliated monolayer.