There is currently great interest in developing understanding of optical properties of monolayers of transition-metal dichalcogenidtes(TMDCs). Is the optical absorption at room temperatures determined by excitons or valence to conduction band transitions? What is the bandgap of these materials? Hanbicki et al. report here absorption measurements on single layers of WS2 and WSe2. They identify contribution from ground and excited exciton states up to room temperature. This allows them to estimate the onset of continuum and determine the bandgap. This is an important contribution to our understanding of optical properties of TMDCs.
Published in: "Solid State Communications".