Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2

Detalhes bibliográficos
Autor(a) principal: Zhao, Weijie
Data de Publicação: 2013
Outros Autores: Ribeiro, R. M., Minglin, Toh, Carvalho, A., Kloc, Christian, Castro Neto, A. H., Eda, Goki
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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spelling 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
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron_str 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
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