WSe₂ Light-Emitting Tunneling Transistors with Enhanced Brightness at Room Temperature.
Del Pozo-Zamudio, O
American Chemical Society
This is the author accepted manuscript. The final version is available from the American Chemical Society via the DOI in this record.
Reason for embargo
Monolayers of molybdenum and tungsten dichalcogenides are direct bandgap semiconductors, which makes them promising for optoelectronic applications. In particular, van der Waals heterostructures consisting of monolayers of MoS2 sandwiched between atomically thin hexagonal boron nitride (hBN) and graphene electrodes allows one to obtain light emitting quantum wells (LEQWs) with low-temperature external quantum efficiency (EQE) of 1%. However, the EQE of MoS2- and MoSe2-based LEQWs shows behavior common for many other materials: it decreases fast from cryogenic conditions to room temperature, undermining their practical applications. Here we compare MoSe2 and WSe2 LEQWs. We show that the EQE of WSe2 devices grows with temperature, with room temperature EQE reaching 5%, which is 250× more than the previous best performance of MoS2 and MoSe2 quantum wells in ambient conditions. We attribute such different temperature dependences to the inverted sign of spin-orbit splitting of conduction band states in tungsten and molybdenum dichalcogenides, which makes the lowest-energy exciton in WSe2 dark.
This work was supported by European Research Council Synergy Grant Hetero2D, EC-FET European Graphene Flagship, The Royal Society, Royal Academy of Engineering, U.S. Army, European Science Foundation (ESF) under the EUROCORES Programme EuroGRAPHENE (GOSPEL), Engineering and Physical Sciences Research Council (UK), the Leverhulme Trust (UK), U.S. Office of Naval Research, U.S. Defence Threat Reduction Agency, U.S. Air Force Office of Scientific Research, FP7 ITN S3NANO, SEP-Mexico and CONACYT.
Vol. 15, No 12, pp. 8223–8228.
Place of publication