Controllable Growth of Large-Size Crystalline MoS2 and Resist-Free Transfer Assisted with a Cu Thin Film

Two-dimensional MoS₂ is a promising material for future nanoelectronics and optoelectronics. It has remained a great challenge to grow large-size crystalline and high surface coverage monolayer MoS₂. In this work, we investigate the controllable growth of monolayer MoS₂ evolving from triangular flakes to continuous thin films by optimizing the concentration of gaseous MoS₂, which has been shown a both thermodynamic and kinetic growth factor. A single-crystal monolayer MoS₂ larger than 300 μm was successfully grown by suppressing the nuclei density and supplying sufficient source. Furthermore, we present a facile process of transferring the centimeter scale MoS₂ assisted with a copper thin film. Our results show the absence of observable residues or wrinkles after we transfer MoS₂ from the growth substrates onto flat substrates using this technique, which can be further extended to transfer other two-dimensional layered materials.