Room-Temperature Geometrical Circular Photocurrent in Few-Layer MoS2

• Published in: Nano letters Vol. 24; no. 20; pp. 5952 - 5957
• Main Authors: Li, Ziqi, Liu, Jiayun, Rasmita, Abdullah, Zhang, Zhaowei, Gao, Weibo, Chia, Elbert E. M.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 22-05-2024
• Subjects: scanning photocurrent microscopy; valleytronics; two-dimensional materials; symmetry breaking; circular photocurrent; optical chirality
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.4c00057

Valleytronics, i.e., the manipulation of the valley degree of freedom, offers a promising path for energy-efficient electronics. One of the key milestones in this field is the room-temperature manipulation of the valley information in thick-layered material. Using scanning photocurrent microscopy, we achieve this milestone by observing a geometrically dependent circular photocurrent in a few-layer molybdenum disulfide (MoS2) under normal incidence. Such an observation shows that the system symmetry is lower than that of bulk MoS2 material, preserving the optical chirality–valley correspondence. Moreover, the circular photocurrent polarity can be reversed by applying electrical bias. We propose a model where the observed photocurrent results from the symmetry breaking and the built-in field at the electrode–sample interface. Our results show that the valley information is still retained even in thick-layered MoS2 at room temperature and opens up new opportunities for exploiting the valley index through interface engineering in multilayer valleytronics devices.