2D MoS₂ synthesis process enhancement using mixed precursors

Abstract The synthesis of high-quality two-dimensional molybdenum disulfide (MoS 2 ) is a crucial step for achieving novel applications in nanoelectronics and optoelectronics. This study introduces a novel c-cut sapphire pre-treatment strategy using sodium sulfide (Na 2 S) to enhance MoS 2 growth. In this method, the substrate is dipped in a 2 × 10 −2 M deionized water solution of Na 2 S, which facilitates the release of hydrogen sulfide (H 2 S) through a reaction with atmospheric moisture. The H 2 S generated in situ acts as an effective catalyst for the growth of MoS 2 monolayers, offering a viable alternative to the conventional Ar/H 2 gas mixture used in many synthesis protocols. This approach significantly improves the quality, uniformity, and growth rate of MoS 2 layers, as confirmed by XPS, AFM, and Raman analysis, and simplifies the synthesis process by eliminating the need for complex gas flow systems. The results demonstrate that this Na 2 S pretreatment method is both cost-effective and scalable, presenting a promising solution for the efficient and sustainable production of MoS 2 for future technological applications.