1. Photocarrier relaxation and saturable absorption in defect-rich, direct chemical vapor deposition-grown graphene glass.
- Author
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Zhao, Xin, Liu, Fang, Chen, Xu-Dong, Liu, Zhi-Bo, Yan, Xiao-Qing, and Tian, Jian-Guo
- Subjects
HOT carriers ,GRAPHENE ,ACOUSTIC phonons ,PUMP probe spectroscopy ,PHONON scattering ,INSULATING materials - Abstract
Direct growth of large-area uniform graphene films on insulating materials could facilitate the applications of graphene in optoelectronic devices. The ultrafast photocarrier relaxation and saturable absorption of direct chemical vapor deposition-grown graphene glasses, with lots of defects, are studied by using femtosecond time-resolved pump–probe and Z-scan techniques at 800 nm. We find that both the relaxation times associated with hot carrier cooling and the hot phonon effect are greatly suppressed in these defect-rich graphene glasses, which further leads to the increase of both saturation intensity and anisotropy in transient optical response for graphene glasses as compared with defect-free graphene. And, both the suppression effect and saturation intensity increase with the thickness of graphene film. The dominance of defect-assisted carrier-acoustic phonon scattering (i.e., supercollision, the collision of a carrier with both an acoustic phonon and defects) in the cooling process of hot carriers is responsible for the suppression of relaxation time. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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