Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2
Autor(a) principal: | |
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Data de Publicação: | 2013 |
Outros Autores: | , , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/1822/27439 |
Resumo: | It has been well established that single layer MX2 (M=Mo,W and X=S,Se) are direct gap semiconductors with band edges coinciding at the K point in contrast to their indirect gap multilayer counterparts. In few-layer MX2, there are two valleys along the Γ-K line with similar energy. There is little understanding on which of the two valleys forms the conduction band minimum (CBM) in this thickness regime. We investigate the conduction band valley structure in few-layer MX2 by examining the temperature-dependent shift of indirect exciton PL. Highly anisotropic thermal expansion of the lattice and corresponding evolution of the band structure result in distinct peak shift for indirect transitions involving the K and Λ (midpoint along Γ-K) valleys. We identify the origin of the indirect emission and concurrently determine the relative energy of these valleys. Our results show that the two valleys compete in energy in few-layer WSe2. |
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Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2MoS2WS2Optical transitionsFew layerWSe2Transition metal dichalcogenidesindirect band gapstrainthermal expansionphotoluminescence spectroscopyexcitonScience & TechnologyIt has been well established that single layer MX2 (M=Mo,W and X=S,Se) are direct gap semiconductors with band edges coinciding at the K point in contrast to their indirect gap multilayer counterparts. In few-layer MX2, there are two valleys along the Γ-K line with similar energy. There is little understanding on which of the two valleys forms the conduction band minimum (CBM) in this thickness regime. We investigate the conduction band valley structure in few-layer MX2 by examining the temperature-dependent shift of indirect exciton PL. Highly anisotropic thermal expansion of the lattice and corresponding evolution of the band structure result in distinct peak shift for indirect transitions involving the K and Λ (midpoint along Γ-K) valleys. We identify the origin of the indirect emission and concurrently determine the relative energy of these valleys. Our results show that the two valleys compete in energy in few-layer WSe2.G.E acknowledges Singapore National Research Foundation for funding the research under NRF Research Fellowship (NRF-NRFF2011-02) and Graphene Research Centre. R.M.R is thankful for the financial support by FEDER through the COMPETE Program, by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011 and grant nr. SFRH/BSAB/1249/2012 and by the EC under Graphene Flagship (contract no. CNECT-ICT-604391).American Chemical SocietyUniversidade do MinhoZhao, WeijieRibeiro, R. M.Minglin, TohCarvalho, A.Kloc, ChristianCastro Neto, A. H.Eda, Goki2013-112013-11-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/1822/27439eng1530-698410.1021/nl403270khttp://pubs.acs.org/doi/abs/10.1021/nl403270kinfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-07-21T12:52:15Zoai:repositorium.sdum.uminho.pt:1822/27439Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T19:51:19.924851Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2 |
title |
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2 |
spellingShingle |
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2 Zhao, Weijie MoS2 WS2 Optical transitions Few layer WSe2 Transition metal dichalcogenides indirect band gap strain thermal expansion photoluminescence spectroscopy exciton Science & Technology |
title_short |
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2 |
title_full |
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2 |
title_fullStr |
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2 |
title_full_unstemmed |
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2 |
title_sort |
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2 |
author |
Zhao, Weijie |
author_facet |
Zhao, Weijie Ribeiro, R. M. Minglin, Toh Carvalho, A. Kloc, Christian Castro Neto, A. H. Eda, Goki |
author_role |
author |
author2 |
Ribeiro, R. M. Minglin, Toh Carvalho, A. Kloc, Christian Castro Neto, A. H. Eda, Goki |
author2_role |
author author author author author author |
dc.contributor.none.fl_str_mv |
Universidade do Minho |
dc.contributor.author.fl_str_mv |
Zhao, Weijie Ribeiro, R. M. Minglin, Toh Carvalho, A. Kloc, Christian Castro Neto, A. H. Eda, Goki |
dc.subject.por.fl_str_mv |
MoS2 WS2 Optical transitions Few layer WSe2 Transition metal dichalcogenides indirect band gap strain thermal expansion photoluminescence spectroscopy exciton Science & Technology |
topic |
MoS2 WS2 Optical transitions Few layer WSe2 Transition metal dichalcogenides indirect band gap strain thermal expansion photoluminescence spectroscopy exciton Science & Technology |
description |
It has been well established that single layer MX2 (M=Mo,W and X=S,Se) are direct gap semiconductors with band edges coinciding at the K point in contrast to their indirect gap multilayer counterparts. In few-layer MX2, there are two valleys along the Γ-K line with similar energy. There is little understanding on which of the two valleys forms the conduction band minimum (CBM) in this thickness regime. We investigate the conduction band valley structure in few-layer MX2 by examining the temperature-dependent shift of indirect exciton PL. Highly anisotropic thermal expansion of the lattice and corresponding evolution of the band structure result in distinct peak shift for indirect transitions involving the K and Λ (midpoint along Γ-K) valleys. We identify the origin of the indirect emission and concurrently determine the relative energy of these valleys. Our results show that the two valleys compete in energy in few-layer WSe2. |
publishDate |
2013 |
dc.date.none.fl_str_mv |
2013-11 2013-11-01T00:00:00Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/1822/27439 |
url |
http://hdl.handle.net/1822/27439 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
1530-6984 10.1021/nl403270k http://pubs.acs.org/doi/abs/10.1021/nl403270k |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
American Chemical Society |
publisher.none.fl_str_mv |
American Chemical Society |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
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Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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RCAAP |
institution |
RCAAP |
reponame_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
collection |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
repository.name.fl_str_mv |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
repository.mail.fl_str_mv |
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1799133100882526208 |