New Insight into Low-Dimensional Materials with the Low-Voltage Aberration Corrected Stem and Eels
Yung-Chang Lin1*, Po-Wen Chiu2, Kazu Suenaga1
1Nanomaterials Research Institute, Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
2Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan
* Presenter:Yung-Chang Lin,
Aberration corrected scanning transmission electron microscopy (AC-STEM) is one of the most powerful facility for the structure characterization of nanomaterials at atomic precision. AC-STEM can further be used for the chemical analysis of single elements and the investigation of electronic configuration and optical properties via electron energy loss spectroscopy (EELS). Two dimensional materials such as graphene, BN, and transition metal dichalcogenides (TMDCs) not only possess intriguing physical properties but also provide ideal playgrounds for scientists to manipulate the electronic properties atom-by-atom. Examples will be shown of the electron beam induced defect [1,2] and phase transformation [3] in group 6 TMDCs. Discovery of unexpected huge Peierls distortion in single carbon chain [4] and the spin state of single transition metal atom in graphene [5] will also be presented. In optics, the photoluminescence of WS2 strongly influenced by impurities and defects is observed in hexagonal-shape WS2 grown by chemical vapor deposition [6].

[1] Y.C. Lin et al., Nature Comm. 6, 6736 (2015).
[2] Y.C. Lin et al., Adv. Mater. 26, 2857-2861 (2014).
[3] Y.C. Lin et al., Nature Nanotech. 9, 391-396 (2014).
[4] Y.C. Lin et al., Nano Lett. 17, 494-500 (2017).
[5] Y.C. Lin et al., Phys. Rev. Lett. 115, 206803 (2015).
[6] Y.C. Lin et al., Adv. Funct. Mater. in press (2017)

Keywords: STEM, EELS, 2D materials, photoluminescence, spin state