Measurement of high exciton binding energy in the monolayer transition-metal dichalcogenides WS2 and WSe2
By Aubrey T. Hanbicki, M. Currie, G. Kioseoglou, A. Friedman, B. Jonker. 2014
306 citations recorded by the source corpus.
Abstract Monolayer transition-metal dichalcogenides are direct gap semiconductors with great promise for optoelectronic devices. Although spatial correlation of electrons and holes plays a key role, there is little experimental information on such fundamental properties as exciton binding energies and band gaps. We report here an experimental determination of exciton excited states and binding energies for monolayer WS 2 and WSe 2 . We observe peaks in the optical reflectivity/absorption spectra corresponding to the ground- and excited-state excitons (1 s and 2 s states). From these features, we determine lower bounds free of any model assumptions for the exciton binding energies as E 2s A − E 1s A of 0.83 eV and 0.79 eV for WS 2 and WSe 2 , respectively, and for the corresponding band gaps E g ≥ E 2s A of 2.90 and 2.53 eV at 4 K. Because the binding energies are large, the true band gap is substantially higher than the dominant spectral feature commonly observed with photoluminescence. This information is critical for emerging applications, and provides new insight into these novel monolayer semiconductors.
Subfields: Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/9a54c8b02d9003ca68c4446b70bd7afd2c0175a9
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Citations in the corpus
- Wafer-scale synthesis of monolayer WS2 for high-performance flexible photodetectors by enhanced chemical vapor deposition (2018, background): “05 eV [12], and large exciton binding energies of 700–800 meV [13, 14].”
- Molecular-beam epitaxy of monolayer and bilayer WSe2: a scanning tunneling microscopy/spectroscopy study and deduction of exciton binding energy (2015, background): “Indeed, giant excitonic effect in ultrathin TMDs originating from enhanced Coulomb interaction between electrons and holes due to spatial confinement and reduced dielectric screening is one of the remarkable properties of the 2D systems, which are attracting extensive theoretical and experimental at”