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Carl V. Thompson. Morgan, Caitlin D Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. Massachusetts Institute of Technology. Department of Materials Science and Engineering 2009-03-16T19:47:08Z 2009-03-16T19:47:08Z 2007 2007 http://hdl.handle.net/1721.1/44816 301368410 Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007. Includes bibliographical references (leaves 36-37). The effects of pretreatment of iron catalyst for carbon nanotube (CNT) growth was studied. CNTs were grown on Fe/A1203 (1/10 nm) thin-film catalyst deposited on silicon substrates via exposure to C2H4 in a thermal chemical vapor deposition (CVD) furnace. During CVD, the sample was exposed to a carrier gas (Argon) for the 35-minute temperature ramp, and 15-minute anneal, then to a mix of carrier gas and ethylene for a 15-minute growth stage. Experiments were performed varying the amount of oxygen contaminant in the carrier gas, and the time of hydrogen introduction. Samples were characterized via atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the later hydrogen was introduced, the higher the catalyst density and the taller the CNT carpet. The catalyst efficiency was also shown to increase with later hydrogen introduction. No clear trend was observed between the amount of oxygen in the carrier gas and the height of CNT growth. Data points to the model of catalyst coarsening being crucial to the nucleation and growth of CNTs and the parameters of CNTs grown. Variations in trends are discussed. by Caitlin D. Morgan. S.B. 37 leaves eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Materials Science and Engineering. Effects of catalyst pretreatment for carbon nanotube growth Effects of catalyst pretreatment for CNT growth Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="09b4d108-256d-48fa-beeb-e30884100163"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Effects of catalyst pretreatment for carbon nanotube growth</Title> <Subtitle>Effects of catalyst pretreatment for CNT growth</Subtitle> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2007</PublicationDate> <Authors> <Author> <DisplayName>Morgan, Caitlin D</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Materials Science and Engineering.</Keyword> <Abstract>The effects of pretreatment of iron catalyst for carbon nanotube (CNT) growth was studied. CNTs were grown on Fe/A1203 (1/10 nm) thin-film catalyst deposited on silicon substrates via exposure to C2H4 in a thermal chemical vapor deposition (CVD) furnace. During CVD, the sample was exposed to a carrier gas (Argon) for the 35-minute temperature ramp, and 15-minute anneal, then to a mix of carrier gas and ethylene for a 15-minute growth stage. Experiments were performed varying the amount of oxygen contaminant in the carrier gas, and the time of hydrogen introduction. Samples were characterized via atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the later hydrogen was introduced, the higher the catalyst density and the taller the CNT carpet. The catalyst efficiency was also shown to increase with later hydrogen introduction. No clear trend was observed between the amount of oxygen in the carrier gas and the height of CNT growth. Data points to the model of catalyst coarsening being crucial to the nucleation and growth of CNTs and the parameters of CNTs grown. Variations in trends are discussed.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>