2014/03/31 by Alexey Chernikov, Timothy C. Berkelbach, Heather M. Hill +6 · 6 citations
Physics and Astronomy · #cond-mat.mtrl-sci #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevlett.113.076802
published as Phys. Rev. Lett. 113, 076802 (2014) · published version
arxiv created 2014/09/02 · arxiv updated 2014/09/03
We have experimentally determined the energies of the ground and first four excited excitonic states of the fundamental optical transition in monolayer WS2, a model system for the growing class of atomically thin two-dimensional semiconductor crystals. From the spectra, we establish a large exciton binding energy of 0.32 eV and a pronounced deviation from the usual hydrogenic Rydberg series of energy levels of the excitonic states. We explain both of these results using a microscopic theory in which the non-local nature of the effective dielectric screening modifies the functional form of the Coulomb interaction. These strong but unconventional electron-hole interactions are expected to be ubiquitous in atomically thin materials.