Defects usually play an important role in tailoring various properties of two-dimensional materials. Defects in two-dimensional monolayer molybdenum disulphide may be responsible for large variation of electric and optical properties. Here we present a comprehensive joint experiment–theory investigation of point defects in monolayer molybdenum disulphide prepared by mechanical exfoliation, physical and chemical vapour deposition. Defect species are systematically identified and their concentrations determined by aberration-corrected scanning transmission electron microscopy, and also studied by ab-initio calculation. Defect density up to 3.5 × 1013 cm−2 is found and the dominant category of defects changes from sulphur vacancy in mechanical exfoliation and chemical vapour deposition samples to molybdenum antisite in physical vapour deposition samples. Influence of defects on electronic structure and charge-carrier mobility are predicted by calculation and observed by electric transport measurement. In light of these results, the growth of ultra-high-quality monolayer molybdenum disulphide appears a primary task for the community pursuing high-performance electronic devices.
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机译:缺陷通常在调整二维材料的各种属性中起重要作用。二维单层二硫化钼中的缺陷可能是导致电气和光学性能发生较大变化的原因。在这里,我们提出了一个全面的联合实验-通过机械剥离,物理和化学气相沉积制备的单层二硫化钼中点缺陷的理论研究。系统地识别缺陷种类,并通过像差校正扫描透射电子显微镜确定其浓度,并通过从头算来研究。发现缺陷密度高达3.5×10 13 sup> cm −2 sup>,缺陷的主要类别从机械剥落和化学气相沉积样品中的硫空位转变为物理上的钼反位气相沉积样品。通过计算预测缺陷对电子结构和电荷载流子迁移率的影响,并通过电迁移测量观察。根据这些结果,超高质量单层二硫化钼的生长似乎是追求高性能电子设备的社区的首要任务。
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