It is reported that chemical vapor deposition (CVD) grown bilayer (BL) MoS₂ films are significantly more structurally stable in ambient air than CVD-grown monolayer (ML) MoS₂ films that have been reported to structurally degrade in ambient air. The authors present atomic force microscopy (AFM) images of preheated and as-grown ML and multilayer MoS₂ films after exposure to ambient air for periods of up to 2 years. The AFM images show that, in ambient air, preheated and as-grown BL and thicker-layer MoS₂ films do not exhibit the growth of dendrites that is characteristic of ML degradation. Dendrites are observed to stop at the ML-BL boundary. Raman spectra of BLs exposed for up to 2 years are similar to those reported for as-grown BLs. The greater stability of BLs and thicker layers are attributed to their indirect band gaps that suppress Förster resonance energy transfer processes that have been proposed to be responsible for ML degradation. The results show that BL and thicker-layer transition metal dichalcogenides with indirect band gaps may be structurally stable in air and useful for ambient-air applications.

中文翻译：

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双层二硫化钼在环境空气中的结构稳定性

据报道，化学气相沉积 (CVD) 生长的双层 (BL) MoS ₂膜在环境空气中的结构比已报道的在环境空气中结构降解的CVD 生长的单层 (ML) MoS ₂膜更加稳定。作者展示了暴露在环境空气中长​​达 2 年的预热和生长状态的 ML 和多层 MoS ₂薄膜的原子力显微镜 (AFM) 图像。AFM 图像显示，在环境空气中，预热和生长的 BL 和较厚层的 MoS ₂薄膜不会出现作为 ML 降解特征的枝晶生长。观察到树突停止在 ML-BL 边界。暴露长达 2 年的 BL 的拉曼光谱与所报告的生长 BL 的拉曼光谱相似。BLs 和较厚层的更高稳定性归因于它们的间接带隙抑制了 Förster 共振能量转移过程，该过程被认为是造成 ML 退化的原因。结果表明，BL 和具有间接带隙的较厚层过渡金属二硫属元素化物在空气中结构稳定，可用于环境空气应用。