钒掺杂调控MoS2层间耦合的能量损失近边结构（ELNES）研究

层间耦合（层间电子态密度、层间电荷密度或层间化学键）对二维材料的性质具有重要影响。我们利用电学测量与理论计算从侧面证实钒（V）替位掺杂Mo原子能够有效增强MoS2的层间耦合使其呈现出层数依赖电学性质，但直接实验证据的缺乏对理解掺杂调控层间耦合的微观机制和设计基于层数依赖电学性质的新型电子器件产生了不利影响。能量损失近边结构（ELNES）能够反应层间耦合在费米能级附近产生的层间电子态的分布情况，扫描透射电子显微镜-电子能量损失谱（STEM-EELS）技术可在高空间分辨率和高能量分辨率上探测材料中元素的ELNES。本项目拟利用STEM-EELS技术测量不同层数V掺杂/未掺杂MoS2的ELNES，通过分析不同层数V掺杂MoS2费米能级附近未被占据电子态的变化情况直接揭示V掺杂调控MoS2层间耦合的微观机制，为二维材料层间耦合调控和设计基于层数依赖电学性质的新型电子器件提供新思路。

Interlayer coupling (density of electronic interlayer states, density of interlayer charge or interlayer chemical bonding) substantially exerts influence on the 2D materials' properties. We showed that substitional doping of Mo with vanadium (V) atoms in MoS2 enhances its interlayer coupling greatly leading MoS2 to present layer-dependent electronic properties. However, the lack of direct experimental evidence for this tuning process results in difficulty on the understanding microscopic mechanisms for the enhanced interlayer coupling and on the design of novel electronic devices based on layer-dependent electronic properties. Energy-loss near edge structure (ELNES) can detect the electronic interlayer states (unoccupied states) derived from interlayer coupling near the Fermi level in materials and scanning-transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) can be used to measure ELNES of elements in the material with high space and energy resolution. In this proposal, we propose to measure the ELNES of elements in V-doped and pristine MoS2 with different layers. Through analysis of the unoccupied states distribution near Fermi level to directly reveal the microscopic mechanisms for the enhanced interlayer coupling, which would provide new insights for the interlayer coupling tuning in 2D materials and the novel electronic devices design based on layer-dependent electronic properties.