Synthesis of large-scale, uniform, easily transferable, and highly crystalline monolayer (1L) molybdenum disulfide (MoS2) on different substrates is a challenge and could decide its suitability for opto-electronic device applications. Herein, we report a facile NaCl-assisted Chemical Vapor Deposition (CVD) synthesis of high-quality MoS2 on amorphous, crystalline and layered substrates. Optical microscopy and Raman spectroscopy show that sapphire and SiO2/Si are suitable substrates for large 1L-MoS2 flakes growth, while mica is excellent for large-area continuous films. Comparatively lesser full-width-at-half-maximum (FWHM) of predominant A exciton peak (which is associated with direct band gap at K point) in photoluminescence spectra of 1L-MoS2 on sapphire suggests its high crystalline quality. However, 1L-MoS2 on other substrates, especially on quartz and bare Si show poor crystalline quality. The study depicts that the NaCl assists in the formation of seeding promoter such as water-soluble layer of Na2S and/or Na2SO4 on the substrate that helps in 2D planar nucleation of MoS2. The formation of such intermediate seeding layers also helps in layer transfer owing to its easy water solubility. The study could be utilized for large-scale synthesis of 1L-MoS2 on different substrates for high-performance optoelectronic devices.

中文翻译：

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MoS2 的 NaCl 辅助底物依赖性二维平面成核生长

在不同基材上合成大规模、均匀、易于转移和高度结晶的单层 (1L) 二硫化钼 (MoS2) 是一项挑战，可能决定其是否适用于光电器件应用。在此，我们报告了一种在无定形、结晶和层状基材上轻松合成高质量 MoS2 的 NaCl 辅助化学气相沉积 (CVD)。光学显微镜和拉曼光谱表明，蓝宝石和 SiO2/Si 是大型 1L-MoS2 薄片生长的合适基材，而云母则非常适合大面积连续薄膜的生长。蓝宝石上 1L-MoS2 的光致发光光谱中主要 A 激子峰（与 K 点的直接带隙相关）的半峰全宽 (FWHM) 相对较小，表明其晶体质量高。然而，其他基材上的 1L-MoS2，特别是在石英和裸硅上显示出较差的结晶质量。该研究描述了 NaCl 有助于在衬底上形成晶种促进剂，例如 Na2S 和/或 Na2SO4 的水溶性层，这有助于 MoS2 的二维平面成核。由于其易溶于水，这种中间晶种层的形成也有助于层转移。该研究可用于在高性能光电器件的不同基材上大规模合成 1L-MoS2。