Large-area synthesis of high-quality and uniform monolayer WS(2) on reusable Au foils

Large-area monolayer WS(2) is a desirable material for applications in next-generation electronics and optoelectronics. However, the chemical vapour deposition (CVD) with rigid and inert substrates for large-area sample growth suffers from a non-uniform number of layers, small domain size and many defects, and is not compatible with the fabrication process of flexible devices. Here we report the self-limited catalytic surface growth of uniform monolayer WS(2) single crystals of millimetre size and large-area films by ambient-pressure CVD on Au. The weak interaction between the WS(2) and Au enables the intact transfer of the monolayers to arbitrary substrates using the electrochemical bubbling method without sacrificing Au. The WS(2) shows high crystal quality and optical and electrical properties comparable or superior to mechanically exfoliated samples. We also demonstrate the roll-to-roll/bubbling production of large-area flexible films of uniform monolayer, double-layer WS(2) and WS(2)/graphene heterostructures, and batch fabrication of large-area flexible monolayer WS(2) film transistor arrays.