Evidence of indirect gap in monolayer WSe2

Handle URI:
http://hdl.handle.net/10754/625868
Title:
Evidence of indirect gap in monolayer WSe2
Authors:
Hsu, Wei-Ting; Lu, Li-Syuan; Wang, Dean; Huang, Jing-Kai; Li, Ming-Yang; Chang, Tay-Rong; Chou, Yi-Chia ( 0000-0002-7775-2927 ) ; Juang, Zhen-Yu; Jeng, Horng-Tay; Li, Lain-Jong ( 0000-0002-4059-7783 ) ; Chang, Wen-Hao ( 0000-0003-4880-6006 )
Abstract:
Monolayer transition metal dichalcogenides, such as MoS2 and WSe2, have been known as direct gap semiconductors and emerged as new optically active materials for novel device applications. Here we reexamine their direct gap properties by investigating the strain effects on the photoluminescence of monolayer MoS2 and WSe2. Instead of applying stress, we investigate the strain effects by imaging the direct exciton populations in monolayer WSe2–MoS2 and MoSe2–WSe2 lateral heterojunctions with inherent strain inhomogeneity. We find that unstrained monolayer WSe2 is actually an indirect gap material, as manifested in the observed photoluminescence intensity–energy correlation, from which the difference between the direct and indirect optical gaps can be extracted by analyzing the exciton thermal populations. Our findings combined with the estimated exciton binding energy further indicate that monolayer WSe2 exhibits an indirect quasiparticle gap, which has to be reconsidered in further studies for its fundamental properties and device applications.
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Citation:
Hsu W-T, Lu L-S, Wang D, Huang J-K, Li M-Y, et al. (2017) Evidence of indirect gap in monolayer WSe2 . Nature Communications 8. Available: http://dx.doi.org/10.1038/s41467-017-01012-6.
Publisher:
Springer Nature
Journal:
Nature Communications
Issue Date:
9-Oct-2017
DOI:
10.1038/s41467-017-01012-6
Type:
Article
ISSN:
2041-1723
Sponsors:
This work was supported by the Ministry of Science and Technology (MOST) of Taiwan (MOST-104-2628-M-009-002-MY3, MOST-105-2119-M-009-014-MY3) and AOARD (FA2386-16-1-4035). W.-H.C. acknowledges the supports from the Center for Interdisciplinary Science of NCTU. T.-R.C. acknowledges the supports from MOST and NCKU. H.-T.J. acknowledges the supports from MOST, NTHU and Academia Sinica. T.-R.C. and H.-T.J. also thank NCHC, CINC-NTU and NCTS for technical supports.
Additional Links:
https://www.nature.com/articles/s41467-017-01012-6
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorHsu, Wei-Tingen
dc.contributor.authorLu, Li-Syuanen
dc.contributor.authorWang, Deanen
dc.contributor.authorHuang, Jing-Kaien
dc.contributor.authorLi, Ming-Yangen
dc.contributor.authorChang, Tay-Rongen
dc.contributor.authorChou, Yi-Chiaen
dc.contributor.authorJuang, Zhen-Yuen
dc.contributor.authorJeng, Horng-Tayen
dc.contributor.authorLi, Lain-Jongen
dc.contributor.authorChang, Wen-Haoen
dc.date.accessioned2017-10-17T08:48:35Z-
dc.date.available2017-10-17T08:48:35Z-
dc.date.issued2017-10-09en
dc.identifier.citationHsu W-T, Lu L-S, Wang D, Huang J-K, Li M-Y, et al. (2017) Evidence of indirect gap in monolayer WSe2 . Nature Communications 8. Available: http://dx.doi.org/10.1038/s41467-017-01012-6.en
dc.identifier.issn2041-1723en
dc.identifier.doi10.1038/s41467-017-01012-6en
dc.identifier.urihttp://hdl.handle.net/10754/625868-
dc.description.abstractMonolayer transition metal dichalcogenides, such as MoS2 and WSe2, have been known as direct gap semiconductors and emerged as new optically active materials for novel device applications. Here we reexamine their direct gap properties by investigating the strain effects on the photoluminescence of monolayer MoS2 and WSe2. Instead of applying stress, we investigate the strain effects by imaging the direct exciton populations in monolayer WSe2–MoS2 and MoSe2–WSe2 lateral heterojunctions with inherent strain inhomogeneity. We find that unstrained monolayer WSe2 is actually an indirect gap material, as manifested in the observed photoluminescence intensity–energy correlation, from which the difference between the direct and indirect optical gaps can be extracted by analyzing the exciton thermal populations. Our findings combined with the estimated exciton binding energy further indicate that monolayer WSe2 exhibits an indirect quasiparticle gap, which has to be reconsidered in further studies for its fundamental properties and device applications.en
dc.description.sponsorshipThis work was supported by the Ministry of Science and Technology (MOST) of Taiwan (MOST-104-2628-M-009-002-MY3, MOST-105-2119-M-009-014-MY3) and AOARD (FA2386-16-1-4035). W.-H.C. acknowledges the supports from the Center for Interdisciplinary Science of NCTU. T.-R.C. acknowledges the supports from MOST and NCKU. H.-T.J. acknowledges the supports from MOST, NTHU and Academia Sinica. T.-R.C. and H.-T.J. also thank NCHC, CINC-NTU and NCTS for technical supports.en
dc.publisherSpringer Natureen
dc.relation.urlhttps://www.nature.com/articles/s41467-017-01012-6en
dc.rightsThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.en
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.titleEvidence of indirect gap in monolayer WSe2en
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalNature Communicationsen
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.institutionDepartment of Electrophysics, National Chiao Tung University, Hsinchu, 30010, Taiwanen
dc.contributor.institutionResearch Center for Applied Sciences, Academia Sinica, Taipei, 10617, Taiwanen
dc.contributor.institutionDepartment of Physics, National Cheng Kung University, Tainan, 70101, Taiwanen
dc.contributor.institutionDepartment of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwanen
kaust.authorHuang, Jing-Kaien
kaust.authorLi, Lain-Jongen
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