Please use this identifier to cite or link to this item: http://hdl.handle.net/1843/IACO-84WSZV
Full metadata record
DC FieldValueLanguage
dc.contributor.advisor1Juan Carlos Gonzalez Perezpt_BR
dc.contributor.advisor-co1Marcus Vinicius Baeta Moreirapt_BR
dc.contributor.referee1Alfredo Gontijo de Oliveirapt_BR
dc.contributor.referee2Vagner Eustaquio de Carvalhopt_BR
dc.contributor.referee3Angelo Malchias de Souzapt_BR
dc.contributor.referee4Antonio Ferreira da Cunhapt_BR
dc.creatorRodrigo Ribeiro de Andradept_BR
dc.date.accessioned2019-08-13T09:14:01Z-
dc.date.available2019-08-13T09:14:01Z-
dc.date.issued2010-02-25pt_BR
dc.identifier.urihttp://hdl.handle.net/1843/IACO-84WSZV-
dc.description.abstractThis Thesis reports the experimental and theoretical works related to the growth and characterization of free-standing gallium indium arsenide nanowires grown by Molecular Beam Epitaxy (MBE). The growth mechanisms of free-standing nanowires remain barely known and explored in its fundamental aspects. The theoretical models of the formation of free-standing nanowires are based on the classical vapor-solid-liquid (VLS) mechanism suggested by Wagner and Ellis in the 1960 decade or on the surface diffusion of precursors adatoms towards the nanowire top, developed in the last decade by several authors.In this study, gallium indium arsenide nanowires were grown by Molecular Beam Epitaxy (MBE) on GaAs (111)B substrates coated with Au nanoparticles catalytic. This Au nanoparticles has an average diameter of 5nm. The Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were use to characterize morphology, chemical composition and crystalline structure of individual nanowires. We use thediffraction of X-rays in coplanar and grazing incidence geometry (GID Grazing Incidence Diffraction) to analyze a large nanowires set. The anomalous diffraction of Xrays analysis complemented these studies.Our results show that the nanowires has a cubic symmetry like spharelite (zinc blende) oriented along [111]B in the shape of hexagonal bars surrounded by six vertical {110} facets. Chemical composition analysis shows that they were composed of the indium, gallium and arsenic elements, all homogeneously distributed along the nanowire. The presence of Ga in the chemical composition of the nanowire was surprising because only indium and arsenide were used as precursors during the growth. The MBE Ga source remained cold and locked during the nanowire growth. Our results has been found that a strong interdiffusion of substrate material occurs during growth, creating a ternary In(1-x)GaxAs alloy in the nanowires. The GaAs molar fraction was found to increase with the growth temperature and decreases with the As4 beam. This ternary alloy has been attributed to the interdiffusion of Ga adatoms coming from the top substrate monolayers and diffusing towards the sidewalls to nanowires. To explain these results we developed a complementary growth model of free-standing nanowires to include the creation and diffusion of Ga adatoms from the substrate, well explaining the formation of the ternary alloy. This work shows that the diffusion of substrate adatoms strongly modifies the growth mechanisms of nanofios grown by vapor phase epitaxy techniques.pt_BR
dc.description.resumoEssa tese resume estudos experimentais e teóricos relacionados com o crescimento e a caracterização de nanofios auto-sustentados de arseneto de Índio (InAs) crescidos por Epitaxia por Feixes Moleculares. Os mecanismos de crescimento de nanofios auto-sustentados de InAs são pouco conhecidos e explorados nos seus aspectos fundamentais. Os modelos teóricos que explicam a formação de nanofios auto-sustentados são baseados no modelo clássico, vapor-sólido-líquido (VLS) sugerido por Wagner e Ellis na década de 1960 ou pelo modelo de difusão superficial de átomos para o topo do nanofio desenvolvido na ultima década por vários autores. Neste trabalho nanofios auto-sustentados de InAs e verticalmente alinhados foram crescidos utilizando a técnica de Epitaxia por Feixe Molecular e estudados por diferentes técnicas morfológicas, estruturais e químicas. Nossas análises indicam a ocorrência de uma forte interdifusão do material do substrato durante o crescimento criando nanofios compostos de uma liga ternária. Adicionalmente, a fração molar de GaAs nos nanofios aumenta com a temperatura e diminui com a pressão equivalente de As4. A formação de da liga ternária é atribuí­da à difusão de átomos de gálio das camadas superficiais do substrato através das paredes laterais do nanofio na direção da gota catalisadora localizada no seu topo. Um novo modelo de crescimento de nanofios auto-sustentados foi proposto para levar em consideração a criação e difusão de átomos de gálio do substrato explicando satisfatoriamente a formação da liga ternária. Esse trabalho mostra que a difusão de átomos vindos do substrato pode modificar significativamente o mecanismo de crescimento de nanofios auto-sustentados crescidos por técnicas de epitaxia na fase vapor.pt_BR
dc.languagePortuguêspt_BR
dc.publisherUniversidade Federal de Minas Geraispt_BR
dc.publisher.initialsUFMGpt_BR
dc.rightsAcesso Abertopt_BR
dc.subjectNanofios autosustentadospt_BR
dc.subjectNanofios semicondutorespt_BR
dc.subjectArseneto de índiopt_BR
dc.subjectCrescimento de nanofiospt_BR
dc.subjectArseneto de gáliopt_BR
dc.subject.otherNanofios auto-sustentadospt_BR
dc.subject.otherNanofios semicondutorespt_BR
dc.subject.otherMolecular Beam Epitaxypt_BR
dc.subject.otherCrescimento de nanofiospt_BR
dc.subject.otherFísicapt_BR
dc.titleCrescimento de nanofios auto-sustentados de arseneto de índio por epitaxia por feixes molecularespt_BR
dc.typeTese de Doutoradopt_BR
Appears in Collections:Teses de Doutorado

Files in This Item:
File Description SizeFormat 
rodrigoandrade.tese.pdf8.46 MBAdobe PDFView/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.