Building Bilayer MoS₂ with Versatile Morphologies via Etching-And-Growth Coexisting Method

The etch-engineering is a feasible avenue to tailor the layer number and morphology of 2D layered materials during the chemical vapor deposition (CVD) growth. However, less reports strengthen the etch-engineering used in the fabrication of high-quality transition metal dichalcogenide (TMD) materials with tunable layers and desirable morphologies to improve their prominent performance in electronic and optoelectronic devices. Here, an etching-and-growth coexistence method is reported to directly synthesize high-quality, high-symmetric MoS₂ bilayers with versatile morphologies via CVD. The growth mechanism is intensively elucidated through analyzing the carrier Ar perturbation associated with the precursor concentration variations, revealing four growth stages including the growth-priority, local-etching, equilibrium of etching and growth, and etching-priority. The as-grown polygonal bilayer MoS₂ exhibits a uniform characteristic, attributed to the formation of the high-quality single crystal bilayer MoS₂ owing to the limitation of the multigrain generation. The work not only enriches the understanding of the growth mechanism of the direct fabrication of TMD materials, but also offers a controllable protocol to engineer their morphologies and the shapes, which can benefit their applications in the electronic and optoelectronic devices.