Abstract
A key feature of monolayer semiconductors, such as transition-metal dichalcogenides, is the poorly screened Coulomb potential, which leads to a large exciton binding energy () and strong renormalization of the quasiparticle band gap () by carriers. The latter has been difficult to determine due to a cancellation in changes of and , resulting in little change in optical transition energy at different carrier densities. Here, we quantify band-gap renormalization in macroscopic single crystal monolayers on using time and angle-resolved photoemission spectroscopy. At an excitation density above the Mott threshold, decreases by as much as 360 meV. We compare the carrier density-dependent with previous theoretical calculations and show the necessity of knowing both doping and excitation densities in quantifying the band gap.
- Received 19 February 2019
DOI:https://doi.org/10.1103/PhysRevLett.122.246803
© 2019 American Physical Society