Monolayer MoS2 Growth on Au Foils and On‐Site Domain Boundary Imaging

Controllable synthesis of large domain, high‐quality monolayer MoS 2 is the basic premise both for exploring some fundamental physical issues, and for engineering its applications in nanoelectronics, optoelectronics, etc. Herein, by introducing H 2 as carrier gas, the successful synthesis of large domain monolayer MoS 2 triangular flakes on Au foils, with the edge length approaching to 80 mm is reported. The growth process is proposed to be mediated by two competitive effects with H 2 acting as both a reduction promoter for efficient sulfurization of MoO 3 and an etching reagent of resulting MoS 2 flakes. By using low‐energy electron microscopy/diffraction, the crystal orientations and domain boundaries of MoS 2 flakes directly on Au foils for the first time are further identified. These on‐site and transfer‐free characterizations should shed light on the initial growth and the aggregation of MoS 2 on arbitrary substrates, further guiding the growth toward large domain flakes or monolayer films.