The ultimate limitations on carrier mobilities in metal dichalcogenides, and the dynamics associated with carrier relaxation, are unclear. We present measurements of the frequency-dependent conductivity of multilayer dichalcogenide ${\mathrm{MoS}}_2$ by optical-pump terahertz-probe spectroscopy. We find mobilities in this material approaching 4200 ${\mathrm{cm}}^2$ ${\mathrm{V}}^{-1}$ ${\mathrm{s}}^{-1}$ at low temperatures. The temperature dependence of scattering indicates that the mobility, an order of magnitude larger than previously reported for ${\mathrm{MoS}}_2$, is intrinsically limited by acoustic phonon scattering at THz frequencies. Our measurements of carrier relaxation reveal picosecond cooling times followed by recombination lasting tens of nanoseconds and dominated by Auger scattering into defects. Our results provide a useful context in which to understand and evaluate the performance of ${\mathrm{MoS}}_2$-based electronic and optoelectronic devices.

• Received 25 September 2014
• Revised 7 November 2014

DOI:https://doi.org/10.1103/PhysRevB.90.245402