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Direct observation of giant binding energy modulation of exciton complexes in monolayer MoSe2

Gupta, Garima and Kallatt, Sangeeth and Majumdar, Kausik (2017) Direct observation of giant binding energy modulation of exciton complexes in monolayer MoSe2. In: PHYSICAL REVIEW B, 96 (8).

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Official URL: http://doi.org/10.1103/PhysRevB.96.081403

Abstract

Screening due to the surrounding dielectric medium reshapes the electron-hole interaction potential and plays a pivotal role in deciding the binding energies of strongly bound exciton complexes in quantum confined monolayers of transition metal dichalcogenides (TMDs). However, owing to strong quasiparticle band-gap renormalization in such systems, a direct quantification of estimated shifts in binding energy in different dielectric media remains elusive using optical studies. In this work, by changing the dielectric environment, we show a conspicuous photoluminescence peak shift at low temperature for higher energy excitons (2s, 3s, 4s, 5s) in monolayer MoSe2, while the 1s exciton peak position remains unaltered - a direct evidence of varying compensation between screening induced exciton binding energy modulation and quasiparticle band-gap renormalization. The estimated modulation of binding energy for the 1s exciton is found to be 58.6% (72.8% for 2s, 75.85% for 3s, and 85.6% for 4s) by coating an Al2O3 layer on top, while the corresponding reduction in quasiparticle band-gap is estimated to be 246 meV. Such direct evidence of large tunability of the binding energy of exciton complexes as well as the band-gap in monolayer TMDs holds promise of novel device applications.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre: Division of Electrical Sciences > Electrical Communication Engineering
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Depositing User: Id for Latest eprints
Date Deposited: 01 Sep 2017 07:27
Last Modified: 01 Sep 2017 07:27
URI: http://eprints.iisc.ac.in/id/eprint/57704

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