Tuesday, August 6, 2013

1308.0696 (D. Lagarde et al.)

Carrier and polarization dynamics in monolayer MoS2    [PDF]

D. Lagarde, L. Bouet, X. Marie, C. R. Zhu, B. L. Liu, T. Amand, B. Urbaszek
In monolayer MoS2 optical transitions across the direct bandgap are governed by chiral selection rules, allowing optical valley initialization. In time resolved photoluminescence experiments we find that both the polarization and emission dynamics do not change from 4K to 300K within our time resolution. The created polarization remains stable during the exciton emission time on the order of 4ps. We show that the decrease of the time-integrated polarization with increasing temperature is not due to a shortening of the polarization lifetime induced by intervalley scattering, but due to a more and more non-resonant excitation as the bandgap shifts with temperature. By compensating this change in bandgap energy with the excitation laser energy an emission polarization of 40% is recovered at room temperature, close to the maximum emission polarization for this sample at 4K.
View original: http://arxiv.org/abs/1308.0696

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