Uniformity and Thickness Control of MoS₂ During Thermolysis

A solution-based thermolysis route for MoS₂ synthesis was systematically investigated to identify the key process parameters for achieving scal-able and high-quality two-dimensional MoS₂ with a uniform thickness. MoS₂ was synthesized by spin coating a solution containing (NH₄)₂ MoS₄ as the precursor. The crystallinity was found to be closely related to the process temperature, while the thickness exhibited a stronger dependence on the precursor solution concentration than the other process variables. However, controlling the thickness of MoS₂ is strongly dependent on the solvent properties, such as viscosity. The thickness uniformity and surface coverage could be enhanced by adding ethanolamine to a mixture of N-dimethylformamide and n-butylamine, which hindered the formation of MoS₄²⁻ clusters in the precursor and facilitated the synthesis of uniform thin films. With an appropriate solvent, the MoS₂ thickness can be controlled more precisely by varying the precursor concentration.