Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silício
Autor(a) principal: | |
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Data de Publicação: | 2018 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Manancial - Repositório Digital da UFSM |
Texto Completo: | http://repositorio.ufsm.br/handle/1/13951 |
Resumo: | In this work the structural, optical and electronic properties of hexagonal monolayer compounds of silicon carbide (h-SiC) in pristine form and in the presence of defects like graphene (h- SiC-C) and silicene (h-SiC-Si) nanodomains were studied. The physical properties of these nanostructures were obtained within the Density Funcional Theory framework as implemented in the SIESTA code, where the term of exchange-correlation energy is described by the GGA-PBE. To modulate the interactions between the valence electrons and the ionic core, norm conserved pseudopotencials were used, according the description of Troullier-Martins. The integration of the first Brillouin zone was done using special points generated by a 4 4 1 mesh within the Monkhorst-Pack scheme. The forces were minimized using the Hellmann-Feynman theorem until they are smaller than 0,05 eV/Å. The results show that these structures are metastable when compared with the bulk fases and have semiconductor character. In the presence of the nanodomains new electronic levels appear resulting in a small band gap. This occur due to the C-C bonds (for the h-SiC-C) and Si-Si bonds (for the h-SiC-Si), as can be seen in the projected density of states. The charge density isosurfaces show that for the h-SiC-C, in the nanodomain, the valence band minimum (VBM) has a bonding character and the conduction band maximum (CBM) has a anti-bonding character. The optical absorption coe cient was also calculated. In the pristine form was observed only a single absorption peak for photons parallely polarized to the plane of the h-SiC in the region of visible light. For the h-SiC-C were observed more absorption peaks in the visible light region. For the h-SiC-Si besides the absorption peaks for photons parallely polarized to the monolayer plane, were observed also peaks of absorption for photons perpendicularly polarized to the monolayer plane. |
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Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silícioTheoretical study of graphene and silicene nanodomains in silicon carbideCarbeto de silícioMonocamadasNanoestruturas 2DTeoria do funcional da densidadeSilicon carbideMonolayers2D NanostructuresDensity functional theoryCNPQ::CIENCIAS EXATAS E DA TERRA::FISICAIn this work the structural, optical and electronic properties of hexagonal monolayer compounds of silicon carbide (h-SiC) in pristine form and in the presence of defects like graphene (h- SiC-C) and silicene (h-SiC-Si) nanodomains were studied. The physical properties of these nanostructures were obtained within the Density Funcional Theory framework as implemented in the SIESTA code, where the term of exchange-correlation energy is described by the GGA-PBE. To modulate the interactions between the valence electrons and the ionic core, norm conserved pseudopotencials were used, according the description of Troullier-Martins. The integration of the first Brillouin zone was done using special points generated by a 4 4 1 mesh within the Monkhorst-Pack scheme. The forces were minimized using the Hellmann-Feynman theorem until they are smaller than 0,05 eV/Å. The results show that these structures are metastable when compared with the bulk fases and have semiconductor character. In the presence of the nanodomains new electronic levels appear resulting in a small band gap. This occur due to the C-C bonds (for the h-SiC-C) and Si-Si bonds (for the h-SiC-Si), as can be seen in the projected density of states. The charge density isosurfaces show that for the h-SiC-C, in the nanodomain, the valence band minimum (VBM) has a bonding character and the conduction band maximum (CBM) has a anti-bonding character. The optical absorption coe cient was also calculated. In the pristine form was observed only a single absorption peak for photons parallely polarized to the plane of the h-SiC in the region of visible light. For the h-SiC-C were observed more absorption peaks in the visible light region. For the h-SiC-Si besides the absorption peaks for photons parallely polarized to the monolayer plane, were observed also peaks of absorption for photons perpendicularly polarized to the monolayer plane.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESNeste trabalho foram estudadas as propriedades estruturais, ópticas e eletrônicas de monocamadas de carbeto de silício hexagonal (h-SiC) tanto na sua forma pristina como na presença de defeitos (nanodomínios de grafeno (h-SiC-C) e siliceno(h-SiC-Si)). As propriedades físicas destas nanoestruturas foram obtidas utilizando o formalismo da teoria do funcional da densidade, que é implementada no código computacional SIESTA, sendo o termo de energia de troca-correlação descrito pelo GGA-PBE. Para modelar a interação entre os elétrons de valência e o caroço iônico foram utilizados pseudopotenciais de norma conservada de acordo com a descrição de Troullier-Martins. Utilizando o procedimento de Monkhorst-Pack a integração na primeira zona de Brillouin foi realizada utilizando pontos especiais gerados por uma malha 4 4 1. As forças foram minimizadas até que atingissem valores menores que 0,05 eV/Å isto é realizado utilizando o teorema de Hellman-Feynmann. Os resultados mostram que todas as estruturas são metaestáveis quando comparadas com as fases bulk e possuem caráter semicondutor. É observado que na presença dos nanodomínios novos níveis eletrônicos são introduzidos de modo que o gap diminua. O surgimento destes níveis se deve as ligações C-C (para a h-SiC-C) e Si-Si (para a h-SiC-Si), como pode ser observado pela densidade de estados projetada em diferentes átomos da supercélula. As isosuperfícies de densidade de carga mostram que para a h-SiC-C tem-se, no nanodomínio, um caráter ligante para o topo da banda de valência (VBM) e anti-ligante para o fundo da banda de condução (CBM). Para a h-SiC-Si tem-se um comportamento oposto, o VBM possui um caráter anti-ligante e o CBM um caráter ligante. Foi calculado também o coeficiente de absorção óptica. Para a forma pristina foi observado apenas um pico de absorção de fótons paralelamente polarizados ao plano da monocamada na região do visível. Na h-SiC-C observou-se que a quantidade de picos de absorção aumenta na faixa do visível. Na h-SiC-Si além dos picos de absorção de fótons com polarização paralela ao plano da monocamada são observados picos de absorção de fótons perpendicularmente polarizados ao plano.Universidade Federal de Santa MariaBrasilFísicaUFSMPrograma de Pós-Graduação em FísicaCentro de Ciências Naturais e ExatasBaierle, Rogério Joséhttp://lattes.cnpq.br/7565203547830128Burgo, Thiago Augusto de Limahttp://lattes.cnpq.br/5737213839553155Rigo, Vagner Alexandrehttp://lattes.cnpq.br/8134733370926343Kremer, Luiz Felipe2018-07-30T19:42:34Z2018-07-30T19:42:34Z2018-02-20info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://repositorio.ufsm.br/handle/1/13951porAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/openAccessreponame:Manancial - Repositório Digital da UFSMinstname:Universidade Federal de Santa Maria (UFSM)instacron:UFSM2018-07-30T19:42:34Zoai:repositorio.ufsm.br:1/13951Biblioteca Digital de Teses e Dissertaçõeshttps://repositorio.ufsm.br/ONGhttps://repositorio.ufsm.br/oai/requestatendimento.sib@ufsm.br||tedebc@gmail.comopendoar:2018-07-30T19:42:34Manancial - Repositório Digital da UFSM - Universidade Federal de Santa Maria (UFSM)false |
dc.title.none.fl_str_mv |
Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silício Theoretical study of graphene and silicene nanodomains in silicon carbide |
title |
Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silício |
spellingShingle |
Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silício Kremer, Luiz Felipe Carbeto de silício Monocamadas Nanoestruturas 2D Teoria do funcional da densidade Silicon carbide Monolayers 2D Nanostructures Density functional theory CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
title_short |
Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silício |
title_full |
Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silício |
title_fullStr |
Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silício |
title_full_unstemmed |
Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silício |
title_sort |
Estudo teórico de nanodomínios de grafeno e siliceno em carbeto de silício |
author |
Kremer, Luiz Felipe |
author_facet |
Kremer, Luiz Felipe |
author_role |
author |
dc.contributor.none.fl_str_mv |
Baierle, Rogério José http://lattes.cnpq.br/7565203547830128 Burgo, Thiago Augusto de Lima http://lattes.cnpq.br/5737213839553155 Rigo, Vagner Alexandre http://lattes.cnpq.br/8134733370926343 |
dc.contributor.author.fl_str_mv |
Kremer, Luiz Felipe |
dc.subject.por.fl_str_mv |
Carbeto de silício Monocamadas Nanoestruturas 2D Teoria do funcional da densidade Silicon carbide Monolayers 2D Nanostructures Density functional theory CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
topic |
Carbeto de silício Monocamadas Nanoestruturas 2D Teoria do funcional da densidade Silicon carbide Monolayers 2D Nanostructures Density functional theory CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
description |
In this work the structural, optical and electronic properties of hexagonal monolayer compounds of silicon carbide (h-SiC) in pristine form and in the presence of defects like graphene (h- SiC-C) and silicene (h-SiC-Si) nanodomains were studied. The physical properties of these nanostructures were obtained within the Density Funcional Theory framework as implemented in the SIESTA code, where the term of exchange-correlation energy is described by the GGA-PBE. To modulate the interactions between the valence electrons and the ionic core, norm conserved pseudopotencials were used, according the description of Troullier-Martins. The integration of the first Brillouin zone was done using special points generated by a 4 4 1 mesh within the Monkhorst-Pack scheme. The forces were minimized using the Hellmann-Feynman theorem until they are smaller than 0,05 eV/Å. The results show that these structures are metastable when compared with the bulk fases and have semiconductor character. In the presence of the nanodomains new electronic levels appear resulting in a small band gap. This occur due to the C-C bonds (for the h-SiC-C) and Si-Si bonds (for the h-SiC-Si), as can be seen in the projected density of states. The charge density isosurfaces show that for the h-SiC-C, in the nanodomain, the valence band minimum (VBM) has a bonding character and the conduction band maximum (CBM) has a anti-bonding character. The optical absorption coe cient was also calculated. In the pristine form was observed only a single absorption peak for photons parallely polarized to the plane of the h-SiC in the region of visible light. For the h-SiC-C were observed more absorption peaks in the visible light region. For the h-SiC-Si besides the absorption peaks for photons parallely polarized to the monolayer plane, were observed also peaks of absorption for photons perpendicularly polarized to the monolayer plane. |
publishDate |
2018 |
dc.date.none.fl_str_mv |
2018-07-30T19:42:34Z 2018-07-30T19:42:34Z 2018-02-20 |
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://repositorio.ufsm.br/handle/1/13951 |
url |
http://repositorio.ufsm.br/handle/1/13951 |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.rights.driver.fl_str_mv |
Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess |
rights_invalid_str_mv |
Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Universidade Federal de Santa Maria Brasil Física UFSM Programa de Pós-Graduação em Física Centro de Ciências Naturais e Exatas |
publisher.none.fl_str_mv |
Universidade Federal de Santa Maria Brasil Física UFSM Programa de Pós-Graduação em Física Centro de Ciências Naturais e Exatas |
dc.source.none.fl_str_mv |
reponame:Manancial - Repositório Digital da UFSM instname:Universidade Federal de Santa Maria (UFSM) instacron:UFSM |
instname_str |
Universidade Federal de Santa Maria (UFSM) |
instacron_str |
UFSM |
institution |
UFSM |
reponame_str |
Manancial - Repositório Digital da UFSM |
collection |
Manancial - Repositório Digital da UFSM |
repository.name.fl_str_mv |
Manancial - Repositório Digital da UFSM - Universidade Federal de Santa Maria (UFSM) |
repository.mail.fl_str_mv |
atendimento.sib@ufsm.br||tedebc@gmail.com |
_version_ |
1805922050394554368 |