Author(s): Zhou, WG (Zhou, Wen-Guang); Leng, YC (Leng, Yu-Chen); Liu, LX (Liu, Li-Xiang); Yang, MM (Yang, Ming-Ming); Liu, W (Liu, Wei); Liu, JL (Liu, Jing-Lan); Zhao, P (Zhao, Pei); Liu, Y (Liu, Yi); Wang, LL (Wang, Long-Long); Shang, YX (Shang, Ya-Xuan); Li, XL (Li, Xiao-Li); Zhao, XH (Zhao, Xiao-Hui); Liu, XL (Liu, Xue-Lu); Xu, Y (Xu, Yang)

Source: NANOPHOTONICS Volume: 10 Issue: 10 Pages: 2695-2703 DOI: 10.1515/nanoph-2021-0190 Published: AUG 2021

Abstract: Bilayer graphene (BLG) grown via chemical vapor deposition (CVD) tends to exhibit twisted stacking. The twist angle theta(t) in twisted BLG (tBLG) provides a new degree of freedom for engineering its electronic and optical properties. In this paper, we investigate the theta(t)-dependent optical absorption in tBLG and deeply understand the electronic structure-optical properties correlations. New absorption peaks, whose wavelengths are modified by theta(t), are observed on the feature of optical contrast (OC) in tBLG. Under the corresponding energy excitation, the Raman G mode in tBLG exhibits a significant enhancement. Furthermore, the results of theta(t) obtained by OC absorption peak are verified to be consistent with those by the Raman R mode. All these properties are proved to be related to the energy difference between low-energy Van Hove singularities (EVHS) in the density of states of tBLGs. This work builds a relation between optical absorption and twist angle, providing a viable method to identifying twist angles in tBLGs.

Accession Number: WOS:000686355800010

ISSN: 2192-8606

eISSN: 2192-8614

Full Text: https://www.degruyter.com/document/doi/10.1515/nanoph-2021-0190/html