Optical properties of transition metal dichalcogenides on GaAs
Autor(a) principal: | |
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Data de Publicação: | 2018 |
Tipo de documento: | Dissertação |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFMG |
Texto Completo: | http://hdl.handle.net/1843/41330 https://orcid.org/0000-0002-2665-8148 |
Resumo: | Transition metal dichalcogenides (TMDs) are crystalline structures of the form MX2, where M is a transition metal, like Mo or W, and X is a chalcogenide, as S or Se. They are multilayer structures, with X-M-X covalent bonds within a layer and Van der Waals bonds at the interlayer interfaces. As the thickness is reduced from several layers to a single monolayer, a transition is observed from a semiconductor with indirect band gap to a direct band gap in the visible or near infrared frequencies. Therefore, the TMDs are good candidates for the implementation of ultra-thin optoelectronical devices. For this reason, and also for their interest in the study of new physical phenomena, they have been extensively investigated over the last decade. It is already well established that the optical properties of monolayer TMDs are strongly affected by the substrate. In this work, we will present how the optical properties of three different TMDs, MoS2, WS2 and WSe2, are modified by placing them on GaAs substrates. We investigate samples on three types of substrates: p-doped GaAs, n-doped GaAs and undoped GaAs. The monolayers were obtained by mechanical exfoliation and transfered to the substrates. Since the refraction indexes of GaAs and the TMDs are similar, we had to establish a procedure to locate and deal with suitable monolayers. We present a pectral analysis of the luminescence emission for each case, as well as their Raman spectra. We find that the GaAs substrates produce significant changes in the luminescence of the TMDs, which can be understood with basis on the band alignment of the TMD with GaAs. We conclude that GaAs/TMDs heterojunctions have a great potential for applications as photodetectors and solar cells. |
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Paulo Sergio Soares Guimarãeshttp://lattes.cnpq.br/5493283201428571Leonardo Cristiano CamposJuliana Caldeira Branthttp://lattes.cnpq.br/2703407810034715Rafael Ricardo Rojas López2022-05-03T18:28:32Z2022-05-03T18:28:32Z2018-09-11http://hdl.handle.net/1843/41330https://orcid.org/0000-0002-2665-8148Transition metal dichalcogenides (TMDs) are crystalline structures of the form MX2, where M is a transition metal, like Mo or W, and X is a chalcogenide, as S or Se. They are multilayer structures, with X-M-X covalent bonds within a layer and Van der Waals bonds at the interlayer interfaces. As the thickness is reduced from several layers to a single monolayer, a transition is observed from a semiconductor with indirect band gap to a direct band gap in the visible or near infrared frequencies. Therefore, the TMDs are good candidates for the implementation of ultra-thin optoelectronical devices. For this reason, and also for their interest in the study of new physical phenomena, they have been extensively investigated over the last decade. It is already well established that the optical properties of monolayer TMDs are strongly affected by the substrate. In this work, we will present how the optical properties of three different TMDs, MoS2, WS2 and WSe2, are modified by placing them on GaAs substrates. We investigate samples on three types of substrates: p-doped GaAs, n-doped GaAs and undoped GaAs. The monolayers were obtained by mechanical exfoliation and transfered to the substrates. Since the refraction indexes of GaAs and the TMDs are similar, we had to establish a procedure to locate and deal with suitable monolayers. We present a pectral analysis of the luminescence emission for each case, as well as their Raman spectra. We find that the GaAs substrates produce significant changes in the luminescence of the TMDs, which can be understood with basis on the band alignment of the TMD with GaAs. We conclude that GaAs/TMDs heterojunctions have a great potential for applications as photodetectors and solar cells.Os Dicalcogenetos de Metais de Transição (TMDs) são estruturas cristalinas da forma MX2, onde M é um metal de transição, como Mo ou W, e X é um calcogênio, como S ou Se. Eles são estruturas compostas por multicamadas tipo X-M-X com ligações covalentes na camada e de Van der Waals nas interfaces entre camadas. Quando a espessura é reduzida até o limite de uma camada, pode-se observar uma transição de um semicondutor de gap indireto para um com gap direto em frequências do visível e infravermelho próximo. Assim, os TMDs são bons candidatos para a implementação de dispositivos optoeletrônicos ultrafinos. Por esse motivo, assim como pelo seu interesse no estudo de novos fenômenos físicos, eles tem sido amplamente pesquisados na ultima década. Já está estabelecido que as propriedades óticas dos TMDs são fortemente afetadas pelo substrato. Neste trabalho apresentaremos como as propriedades óticas de três TMDs diferentes, MoS2, WS2 e WSe2, mudam depois deles serem colocadas em substratos de GaAs. Foram investigadas amostras sobre três tipos de substratos: GaAs dopado p, GaAs dopado n, e GaAs não dopado. As monocamadas foram obtidas pelo método de exfoliação mecânica e transferidas ao substrato. Como os índices de refração do GaAs e dos TMDs são muito próximos, tornando muito dificil a visualizção das monocamadas transferidas, estabelecemos um procedimento apropriado para a localização e manipulação dessas monocamadas. Apresentamos a análise espectral da luminescência em cada caso assim como os seus espectros Raman. Achamos que os substratos de GaAs produzem alterações na luminescência dos TMDs que podem ser entendidas com base no alinhamento de bandas dos TMDs com o GaAs. Concluimos que as heteroestruturas GaAs/TMDs tem um grande potencial para aplicações como fotodetetores e celulas solares.CNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas GeraisCAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorengUniversidade Federal de Minas GeraisPrograma de Pós-Graduação em FísicaUFMGBrasilICX - DEPARTAMENTO DE FÍSICAhttp://creativecommons.org/licenses/by-nc-nd/3.0/pt/info:eu-repo/semantics/openAccessPropriedades ópticasMatéria condensadaEspectros molecularesTransition metal dichalcogenidesGaAs2D materialsMonolayerOptical propertiesOptical properties of transition metal dichalcogenides on GaAsinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisreponame:Repositório Institucional da UFMGinstname:Universidade Federal de Minas Gerais (UFMG)instacron:UFMGCC-LICENSElicense_rdflicense_rdfapplication/rdf+xml; charset=utf-8811https://repositorio.ufmg.br/bitstream/1843/41330/5/license_rdfcfd6801dba008cb6adbd9838b81582abMD55ORIGINALDissertacao-NovasNormativas2022-RafaelRojas-pdfa.pdfDissertacao-NovasNormativas2022-RafaelRojas-pdfa.pdfapplication/pdf14632190https://repositorio.ufmg.br/bitstream/1843/41330/7/Dissertacao-NovasNormativas2022-RafaelRojas-pdfa.pdf68f5a6d5f075235e3494f44a3f97b3adMD57LICENSElicense.txtlicense.txttext/plain; charset=utf-82118https://repositorio.ufmg.br/bitstream/1843/41330/8/license.txtcda590c95a0b51b4d15f60c9642ca272MD581843/413302022-05-03 15:28:32.659oai:repositorio.ufmg.br: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ório de PublicaçõesPUBhttps://repositorio.ufmg.br/oaiopendoar:2022-05-03T18:28:32Repositório Institucional da UFMG - Universidade Federal de Minas Gerais (UFMG)false |
dc.title.pt_BR.fl_str_mv |
Optical properties of transition metal dichalcogenides on GaAs |
title |
Optical properties of transition metal dichalcogenides on GaAs |
spellingShingle |
Optical properties of transition metal dichalcogenides on GaAs Rafael Ricardo Rojas López Transition metal dichalcogenides GaAs 2D materials Monolayer Optical properties Propriedades ópticas Matéria condensada Espectros moleculares |
title_short |
Optical properties of transition metal dichalcogenides on GaAs |
title_full |
Optical properties of transition metal dichalcogenides on GaAs |
title_fullStr |
Optical properties of transition metal dichalcogenides on GaAs |
title_full_unstemmed |
Optical properties of transition metal dichalcogenides on GaAs |
title_sort |
Optical properties of transition metal dichalcogenides on GaAs |
author |
Rafael Ricardo Rojas López |
author_facet |
Rafael Ricardo Rojas López |
author_role |
author |
dc.contributor.advisor1.fl_str_mv |
Paulo Sergio Soares Guimarães |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/5493283201428571 |
dc.contributor.referee1.fl_str_mv |
Leonardo Cristiano Campos |
dc.contributor.referee2.fl_str_mv |
Juliana Caldeira Brant |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/2703407810034715 |
dc.contributor.author.fl_str_mv |
Rafael Ricardo Rojas López |
contributor_str_mv |
Paulo Sergio Soares Guimarães Leonardo Cristiano Campos Juliana Caldeira Brant |
dc.subject.por.fl_str_mv |
Transition metal dichalcogenides GaAs 2D materials Monolayer Optical properties |
topic |
Transition metal dichalcogenides GaAs 2D materials Monolayer Optical properties Propriedades ópticas Matéria condensada Espectros moleculares |
dc.subject.other.pt_BR.fl_str_mv |
Propriedades ópticas Matéria condensada Espectros moleculares |
description |
Transition metal dichalcogenides (TMDs) are crystalline structures of the form MX2, where M is a transition metal, like Mo or W, and X is a chalcogenide, as S or Se. They are multilayer structures, with X-M-X covalent bonds within a layer and Van der Waals bonds at the interlayer interfaces. As the thickness is reduced from several layers to a single monolayer, a transition is observed from a semiconductor with indirect band gap to a direct band gap in the visible or near infrared frequencies. Therefore, the TMDs are good candidates for the implementation of ultra-thin optoelectronical devices. For this reason, and also for their interest in the study of new physical phenomena, they have been extensively investigated over the last decade. It is already well established that the optical properties of monolayer TMDs are strongly affected by the substrate. In this work, we will present how the optical properties of three different TMDs, MoS2, WS2 and WSe2, are modified by placing them on GaAs substrates. We investigate samples on three types of substrates: p-doped GaAs, n-doped GaAs and undoped GaAs. The monolayers were obtained by mechanical exfoliation and transfered to the substrates. Since the refraction indexes of GaAs and the TMDs are similar, we had to establish a procedure to locate and deal with suitable monolayers. We present a pectral analysis of the luminescence emission for each case, as well as their Raman spectra. We find that the GaAs substrates produce significant changes in the luminescence of the TMDs, which can be understood with basis on the band alignment of the TMD with GaAs. We conclude that GaAs/TMDs heterojunctions have a great potential for applications as photodetectors and solar cells. |
publishDate |
2018 |
dc.date.issued.fl_str_mv |
2018-09-11 |
dc.date.accessioned.fl_str_mv |
2022-05-03T18:28:32Z |
dc.date.available.fl_str_mv |
2022-05-03T18:28:32Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/1843/41330 |
dc.identifier.orcid.pt_BR.fl_str_mv |
https://orcid.org/0000-0002-2665-8148 |
url |
http://hdl.handle.net/1843/41330 https://orcid.org/0000-0002-2665-8148 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.rights.driver.fl_str_mv |
http://creativecommons.org/licenses/by-nc-nd/3.0/pt/ info:eu-repo/semantics/openAccess |
rights_invalid_str_mv |
http://creativecommons.org/licenses/by-nc-nd/3.0/pt/ |
eu_rights_str_mv |
openAccess |
dc.publisher.none.fl_str_mv |
Universidade Federal de Minas Gerais |
dc.publisher.program.fl_str_mv |
Programa de Pós-Graduação em Física |
dc.publisher.initials.fl_str_mv |
UFMG |
dc.publisher.country.fl_str_mv |
Brasil |
dc.publisher.department.fl_str_mv |
ICX - DEPARTAMENTO DE FÍSICA |
publisher.none.fl_str_mv |
Universidade Federal de Minas Gerais |
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reponame:Repositório Institucional da UFMG instname:Universidade Federal de Minas Gerais (UFMG) instacron:UFMG |
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