High Intrinsic Mobility and Ultrafast Carrier Dynamics in Multilayer Metal Dichalcogenide MoS2

TL;DR

This study measures high carrier mobility and ultrafast carrier relaxation in multilayer MoS2, revealing intrinsic limits and dynamics crucial for electronic and optoelectronic applications.

Contribution

It provides the first detailed frequency-dependent conductivity measurements showing mobility approaching 4200 cm2/Vs and elucidates carrier relaxation processes in multilayer MoS2.

Findings

Mobility in multilayer MoS2 approaches 4200 cm2/Vs at low temperatures.

Carrier cooling occurs within picoseconds, with recombination lasting tens of nanoseconds.

Mobility is limited by acoustic phonon scattering at THz frequencies.

Abstract

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 MoS2 by optical-pump terahertz-probe spectroscopy. We find mobilities in this material approaching 4200 cm2/Vs at low temperatures. The temperature dependence of scattering indicates that the mobility, an order of magnitude larger than previously reported for MoS2, 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 MoS2-based electronic and optoelectronic devices.