Valley carrier dynamics in monolayer molybdenum disulfide from helicity-resolved ultrafast pump-probe spectroscopy

Qinsheng Wang, Shaofeng Ge, Xiao Li, Jun Qiu, Yanxin Ji, Ji Feng, Dong Sun*

*此作品的通讯作者

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221 引用 (Scopus)

摘要

We investigate the valley-related carrier dynamics in monolayer molybdenum disulfide using helicity-resolved nondegenerate ultrafast pump-probe spectroscopy at the vicinity of the high-symmetry K point under the temperature down to 78 K. Monolayer molybdenum disulfide shows remarkable transient reflection signals, in stark contrast to bilayer and bulk molybdenum disulfide due to the enhancement of many-body effect at reduced dimensionality. The helicity-resolved ultrafast time-resolved result shows that the valley polarization is preserved for only several picoseconds before the scattering process makes it undistinguishable. We suggest that the dynamical degradation of valley polarization is attributable primarily to the exciton trapping by defect states in the exfoliated molybdenum disulfide samples. Our experiment and a tight-binding model analysis also show that the perfect valley circular dichroism selectivity is fairly robust against disorder at the K point but quickly decays from the high-symmetry point in the momentum space in the presence of disorder.

源语言英语
页(从-至)11087-11093
页数7
期刊ACS Nano
7
12
DOI
出版状态已出版 - 23 12月 2013
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Wang, Q., Ge, S., Li, X., Qiu, J., Ji, Y., Feng, J., & Sun, D. (2013). Valley carrier dynamics in monolayer molybdenum disulfide from helicity-resolved ultrafast pump-probe spectroscopy. ACS Nano, 7(12), 11087-11093. https://doi.org/10.1021/nn405419h