WSe2 Light-Emitting Tunneling Transistors with Enhanced Brightness at Room Temperature

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• 作者：F. Withers ; O. Del Pozo-Zamudio ; S. Schwarz ; S. Dufferwiel ; P. M. Walker ; T. Godde ; A. P. Rooney ; A. Gholinia ; C. R. Woods ; P. Blake ; S. J. Haigh ; K. Watanabe ; T. Taniguchi ; I. L. Aleiner ; A. K. Geim ; V. I. Fal鈥檏o ; A. I. Tartakovskii ; K. S. Novoselov
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：December 9, 2015
• 年：2015
• 卷：15
• 期：12
• 页码：8223-8228
• 全文大小：415K
• ISSN：1530-6992

文摘

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脳 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鈥搊rbit splitting of conduction band states in tungsten and molybdenum dichalcogenides, which makes the lowest-energy exciton in WSe₂ dark.