Open AccessCorrelation between the optical absorption and twisted angle of bilayer graphene observed by high-resolution reflectance confocal laser microscopy
Author(s) -
Ming-Che Chan,
Yen-Chun Chen,
Bai-Heng Shiue,
Tzi-I Tsai,
Chii-Dong Chen,
Wei-Shiuan Tseng
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.431305
Subject(s) - materials science , optics , absorption (acoustics) , bilayer graphene , microscope , laser , optical axis , resolution (logic) , graphene , physics , nanotechnology , artificial intelligence , computer science , lens (geology)
We report a systematic study of the optical absorption of twisted bilayer graphene (tBLG) across a large range of twist angles from 0° to 30° using a high-resolution reflectance confocal laser microscopy (RCLM) system. The high-quality single crystalline tBLG was synthesized via the efficient plasma enhanced chemical vapor deposition techniques without the need of active heating. The sensitivity of acquired images from the RCLM were better than conventional optical microscopes. Although the highest spatial resolution of RCLM is still lower than scanning electron microscopes, it possesses the advantages of beam-damage and vacuum free. Moreover, the high intensity-resolution (sensitivity) images firstly allowed us to distinguish the slight absorption differences and analyze the correlation between the optical absorption and twisted angle of tBLG after data processing procedures. A maximum absorption (minimum transmission) was observed at the stacking angle of tBLG from 10° to 20°, indicating the interplay between the laser and the electron/hole van-Hove singularities when tBLG oriented around the critical angle (θ c ∼13°). The twisted angle correlated optical absorption paves an alternative way not only to visibly identify the interlayer orientation of tBLG but also to reflect the characterization of the interlayer coupling via its band structure.