Fast and large-area growth of uniform MoS₂ monolayers on molybdenum foils

A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS₂ monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS₂ monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600°C within 1 min. At a lower temperature even down to 500°C, uniform MoS₂ monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the formed monolayers can be nondestructively transferred onto arbitrary substrates by removing the Mo foil using diluted ferric chloride solution and can be successfully fabricated into photodetectors. The results show a novel avenue to efficiently fabricate two-dimensional crystals in a large area in a highly controllable way and should have great potential for the development of large-scale applications of two-dimensional crystals in electrophotonic systems.