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Computational Synthesis of MoS2 Layers by Reactive Molecular Dynamics Simulations: Initial Sulfidation of MoO3 Surfaces
Nano Letters ( IF 9.6 ) Pub Date : 2017-07-06 00:00:00 , DOI: 10.1021/acs.nanolett.7b01727
Sungwook Hong 1 , Aravind Krishnamoorthy 1 , Pankaj Rajak 1 , Subodh Tiwari 1 , Masaaki Misawa 2 , Fuyuki Shimojo 2 , Rajiv K. Kalia 1 , Aiichiro Nakano 1 , Priya Vashishta 1
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Transition metal dichalcogenides (TMDC) like MoS2 are promising candidates for next-generation electric and optoelectronic devices. These TMDC monolayers are typically synthesized by chemical vapor deposition (CVD). However, despite significant amount of empirical work on this CVD growth of monolayered crystals, neither experiment nor theory has been able to decipher mechanisms of selection rules for different growth scenarios, or make predictions of optimized environmental parameters and growth factors. Here, we present an atomic-scale mechanistic analysis of the initial sulfidation process on MoO3 surfaces using first-principles-informed ReaxFF reactive molecular dynamics (RMD) simulations. We identify a three-step reaction process associated with synthesis of the MoS2 samples from MoO3 and S2 precursors: O2 evolution and self-reduction of the MoO3 surface; SO/SO2 formation and S2-assisted reduction; and sulfidation of the reduced surface and Mo–S bond formation. These atomic processes occurring during early stage MoS2 synthesis, which are consistent with experimental observations and existing theoretical literature, provide valuable input for guided rational synthesis of MoS2 and other TMDC crystals by the CVD process.

中文翻译:

反应性分子动力学模拟计算合成MoS 2层:MoO 3表面的初始硫化

像MoS 2一样的过渡金属二硫化碳(TMDC)是下一代电气和光电设备的有希望的候选者。这些TMDC单层通常通过化学气相沉积(CVD)合成。然而,尽管在单层晶体的这种CVD生长方面进行了大量的经验工作,但无论是实验还是理论都无法破译针对不同生长场景的选择规则的机制,也无法对优化的环境参数和生长因子做出预测。在这里,我们使用第一原理的ReaxFF反应分子动力学(RMD)模拟对MoO 3表面上的初始硫化过程进行原子级机理分析。我们确定了与MoS 2合成相关的三步反应过程来自MoO 3和S 2前体的样品:O 2的析出和MoO 3表面的自还原;SO / SO 2形成和S 2辅助还原;硫化和还原的表面以及Mo-S键的形成。这些在MoS 2合成早期阶段发生的原子过程与实验观察和现有的理论文献一致,为通过CVD工艺指导MoS 2和其他TMDC晶体的合理合成提供了有价值的输入。
更新日期:2017-07-08
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