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

TL;DR

This study uses transient absorption microscopy to investigate charge carrier dynamics in bulk MoS2, revealing ultrafast intervalley transfer, energy relaxation, and diffusion properties at room temperature.

Contribution

It provides detailed measurements of charge carrier transfer times, energy relaxation, and diffusion coefficients in bulk MoS2 using a novel microscopy approach.

Findings

Intervalley transfer time of ~0.35 ps

Hot carrier energy relaxation time ~50 ps

Carrier lifetime of ~180 ps

Abstract

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 ps. By monitoring the spatiotemporal dynamics of carriers, we obtained a diffusion coefficient of thermalized electrons of 4.2 cm2/s, corresponding to a mobility of 170 cm2/Vs. We also observed a time-varying diffusion coefficient of hot carriers.