標題: Ultrafast Electron Cooling and Decay in Monolayer WS2 Revealed by Time- and Energy-Resolved Photoemission Electron Microscopy
作者: Li, Yaolong
Liu, Wei
Wang, Yunkun
Xue, Zhaohang
Leng, Yu-Chen
Hu, Aiqin
Yang, Hong
Tan, Ping-Heng
Liu, Yunquan
Misawa, Hiroaki
Sun, Quan
Gao, Yunan
Hu, Xiaoyong
Gong, Qihuang
交大名義發表
National Chiao Tung University
關鍵字: electron cooling defect trapping;transition metal dichalcogenides;ultrafast dynamics;photoemission electron microscopy;energy-resolved
公開日期: 13-May-2020
摘要: A comprehensive understanding of the ultrafast electron dynamics in two-dimensional transition metal dichalcogenides (TMDs) is necessary for their applications in optoelectronic devices. In this work, we contribute a study of ultrafast electron cooling and decay dynamics in the supported and suspended monolayer WS2 by time- and energy-resolved photoemission electron microscopy (PEEM). Electron cooling in the Q valley of the conduction band is clearly resolved in energy and time, on a time scale of 0.3 ps. Electron decay is mainly via a defect trapping process on a time scale of several picoseconds. We observed that the trap states can be produced and increased by laser illumination under an ultrahigh vacuum, and the higher local optical-field intensity led to the faster increase of trap states. The enhanced defect trapping could significantly modify the carrier dynamics and should be paid attention to in photoemission experiments for two-dimensional materials.
URI: http://dx.doi.org/10.1021/acs.nanolett.0c00742
http://hdl.handle.net/11536/154569
ISSN: 1530-6984
DOI: 10.1021/acs.nanolett.0c00742
期刊: NANO LETTERS
Volume: 20
Issue: 5
起始頁: 3747
結束頁: 3753
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