We investigate the valley related carrier dynamics in monolayer MoS₂ using helicity resolved non-degenerate ultrafast pump-probe spectroscopy at the vicinity of the high-symmetry K point under the temperature down to 78 K. Monolayer MoS₂ shows remarkable transient reflection signals, in stark contrast to bilayer and bulk MoS₂ 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 ps before 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 MoS₂ samples.

Date Published: 5 September 2014
PDF: 9 pages
Proc. SPIE 9198, Ultrafast Nonlinear Imaging and Spectroscopy II, 91980M (5 September 2014); doi: 10.1117/12.2063225

Published in SPIE Proceedings Vol. 9198:
Ultrafast Nonlinear Imaging and Spectroscopy II
Zhiwen Liu, Editor(s)