Author(s): Li, YL (Li, Yaolong); Liu, W (Liu, Wei); Wang, YK (Wang, Yunkun); Xue, ZH (Xue, Zhaohang); Leng, YC (Leng, Yu-Chen); Hu, AQ (Hu, Aiqin); Yang, H (Yang, Hong); Tan, PH (Tan, Ping-Heng); Liu, YQ (Liu, Yunquan); Misawa, H (Misawa, Hiroaki); Sun, Q (Sun, Quan); Gao, YN (Gao, Yunan); Hu, XY (Hu, Xiaoyong); Gong, QH (Gong, Qihuang)

Source: NANO LETTERS Volume: 20 Issue: 5 Pages: 3747-3753 DOI: 10.1021/acs.nanolett.0c00742 Published: MAY 13 2020

Abstract: 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.

Accession Number: WOS:000535255300106

PubMed ID: 32242668

Author Identifiers:

Author        Web of Science ResearcherID        ORCID Number

Misawa, Hiroaki         A-4312-2012         0000-0003-1070-387X

SUN, QUAN                  0000-0001-5413-8038

TAN, Ping-Heng         D-1137-2009         0000-0001-6575-1516

ISSN: 1530-6984

eISSN: 1530-6992

Full Text: https://pubs.acs.org/doi/10.1021/acs.nanolett.0c00742