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Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers

Research paper by G. Wang, E. Palleau, T. Amand, S. Tongay, X. Marie, B. Urbaszek

Indexed on: 12 Feb '15Published on: 12 Feb '15Published in: Physics - Materials Science



Abstract

We investigate valley exciton dynamics in MoSe2 monolayers in polarization- and time-resolved photoluminescence (PL) spectroscopy at 4K. Following circularly polarized laser excitation, we record a low circular polarization degree of the PL of typically $\leq5\%$. This is about 10 times lower than the polarization induced under comparable conditions in MoS2 and WSe2 monolayers. The evolution of the exciton polarization as a function of excitation laser energy and power is monitored in PL excitation (PLE) experiments. Fast PL emission times are recorded for both the neutral exciton of $\leq3$ ps and for the charged exciton (trion) of 12 ps.