The dynamics of excited electrons and holes in single layer (SL) MoS2 have so far been difficult to disentangle from the excitons that dominate the optical response of this material. Here, we use time- and angle-resolved photoemission spectroscopy for a SL of MoS2 on a metallic substrate to directly measure the excited free carriers. This allows us to ascertain a direct quasiparticle band gap of 1.95 eV and determine an ultrafast (50 fs) extraction of excited free carriers via the metal in contact with the SL MoS2. This process is of key importance for optoelectronic applications that rely on separated free carriers rather than excitons.
@article{arxiv.1508.07301,
title = {Observation of Ultrafast Free Carrier Dynamics in Single Layer MoS$_2$},
author = {Antonija Grubišić Čabo and Jill A. Miwa and Signe S. Grønborg and Jonathon M. Riley and Jens C. Johannsen and Cephise Cacho and Oliver Alexander and Richard T. Chapman and Emma Springate and Marco Grioni and Jeppe V. Lauritsen and Phil D. C. King and Philip Hofmann and Søren Ulstrup},
journal= {arXiv preprint arXiv:1508.07301},
year = {2016}
}
Comments
15 pages, 4 Figures. To appear in Nano Letters, 2015