Bonnet Noémie, Lee Hae Yeon, Shao Fuhui, Woo Steffi Y, Blazit Jean-Denis, Watanabe Kenji, Taniguchi Takashi, Zobelli Alberto, Stéphan Odile, Kociak Mathieu, Gradečak Silvija, Tizei Luiz H G
Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay, France.
Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02141, United States.
Nano Lett. 2021 Dec 22;21(24):10178-10185. doi: 10.1021/acs.nanolett.1c02600. Epub 2021 Dec 8.
Structural, electronic, and chemical nanoscale modifications of transition metal dichalcogenide monolayers alter their optical properties. A key missing element for complete control is a direct spatial correlation of optical response to nanoscale modifications due to the large gap in spatial resolution between optical spectroscopy and nanometer-resolved techniques. Here, we bridge this gap by obtaining nanometer-resolved optical properties using electron spectroscopy at cryogenic temperatures, specifically electron energy loss spectroscopy for absorption and cathodoluminescence for emission, which are then directly correlated to chemical and structural information. In an h-BN/WS/h-BN heterostructure, we observe local modulation of the trion (X) emission due to tens of nanometer wide dielectric patches. Trion emission also increases in regions where charge accumulation occurs, close to the carbon film supporting the heterostructures. The localized exciton emission (L) detected here is not correlated to strain above 1%, suggesting point defects might be involved in their formation.
过渡金属二硫属化物单层的结构、电子和化学纳米级修饰会改变其光学性质。实现完全控制的一个关键缺失要素是，由于光谱学与纳米级分辨技术之间存在较大的空间分辨率差距，光学响应与纳米级修饰之间缺乏直接的空间相关性。在此，我们通过在低温下使用电子能谱获取纳米级分辨的光学性质来弥合这一差距，具体而言，利用电子能量损失谱进行吸收测量，利用阴极发光进行发射测量，然后将其与化学和结构信息直接关联起来。在h-BN/WS/h-BN异质结构中，我们观察到由于数十纳米宽的介电斑块导致的三重子（X）发射的局部调制。在靠近支撑异质结构的碳膜处电荷积累发生的区域，三重子发射也会增加。此处检测到的局域激子发射（L）与应变高于1%无关，这表明点缺陷可能参与了它们的形成。
