Charge carrier dynamics in bulk MoS2 crystal studied by transient absorption microscopy

We report a transient absorption microscopy study of charge carrier dynamics in bulk MoS2 crystals at room temperature. Charge carriers are injected by interband absorption of a 555-nm pulse, and probed by measuring differential reflection of a time-delayed and spatially scanned 660-nm pulse. We find an intervalley transfer time of about 0.35 ps, an energy relaxation time of hot carriers on the order of 50 ps, and a carrier lifetime of 180 ± 20 ps. By monitoring the spatiotemporal dynamics of carriers, we obtained a diffusion coefficient of thermalized electrons of 4.2 ± 0.5 cm2/s, corresponding to a mobility of 170 ± 20 cm2/Vs. We also observed a time-varying diffusion coefficient of hot carriers.