Journal
ACS NANO
Volume 7, Issue 12, Pages 11087-11093Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nn405419h
Keywords
molybdenum disulfide; transition-metal dichalcogenides; ultrafast spectroscopy valley carrier dynamics; disorder
Categories
Funding
- National Basic Research Program of China (973) [2012CB921300, 2013CB921900]
- National Natural Science Foundation of China (NSFC) [11274015, 11174009]
- Specialized Research Fund for the Doctoral Program of Higher Education of China [20120001110066]
Ask authors/readers for more resources
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. Mono layer 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.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available