2026-09-19T11:02:29Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/1125012022-01-13T07:55:22Zcom_1721.1_7582com_1721.1_7581col_1721.1_131024
Eugene A. Fitzgerald.
Baum, Brian K
Massachusetts Institute of Technology. Department of Materials Science and Engineering.
Massachusetts Institute of Technology. Department of Materials Science and Engineering
2017-12-05T19:15:39Z
2017-12-05T19:15:39Z
2010
2010
http://hdl.handle.net/1721.1/112501
1011525220
Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 45-46).
Metal-organic chemical vapor deposition (MOCVD) was used to grow InAsP graded layers and AlAs/GaAs superlattices for materials studies related to thermophotovoltaics and thermoelectrics respectively. High resolution x-ray diffraction (HRXRD) was used to determine the As concentration in each of the InAsP layers. Arsenic concentration was found to vary linearly with the percentage of AsH3 in the reactive gas flow up to 60 % deposited, and had an asymptotic relationship for higher incorporated concentrations. Higher growth temperatures reduced As incorporation. Transmission electron microscopy (TEM) images were used to determine layer thicknesses. The growth rate of InAsP layers was found to be independent of growth temperature and the percentage of As. Superlattice samples with 0 %, 5 %, 10 %, and 20 % variations in the superlattice period were grown via MOCVD and analyzed using HRXRD. The intensities of the satellite peaks were found to decrease and broaden with increasing variation in the period length and disappeared completely in samples with up to 10 % variation. Thermal conductivity measurements performed using an optical pump-probe technique showed lower thermal conductivities for samples with greater variation. The irregularity of the superlattice period is believed to enhance the structure's ability to impede phonon propagation.
by Brian K . Baum.
S.B.
46 pages
eng
Massachusetts Institute of Technology
MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.
http://dspace.mit.edu/handle/1721.1/7582
Materials Science and Engineering.
Analysis of materials properties of thin film structures for thermoelectric and thermophotovoltaic applications
Thesis
application/pdf
false
Publication
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="6e2ad0e6-9f82-443c-8e21-bce0f03e1a2b">
<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>Analysis of materials properties of thin film structures for thermoelectric and thermophotovoltaic applications</Title>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2010</PublicationDate>
<Authors>
<Author>
<DisplayName>Baum, Brian K</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>Metal-organic chemical vapor deposition (MOCVD) was used to grow InAsP graded layers and AlAs/GaAs superlattices for materials studies related to thermophotovoltaics and thermoelectrics respectively. High resolution x-ray diffraction (HRXRD) was used to determine the As concentration in each of the InAsP layers. Arsenic concentration was found to vary linearly with the percentage of AsH3 in the reactive gas flow up to 60 % deposited, and had an asymptotic relationship for higher incorporated concentrations. Higher growth temperatures reduced As incorporation. Transmission electron microscopy (TEM) images were used to determine layer thicknesses. The growth rate of InAsP layers was found to be independent of growth temperature and the percentage of As. Superlattice samples with 0 %, 5 %, 10 %, and 20 % variations in the superlattice period were grown via MOCVD and analyzed using HRXRD. The intensities of the satellite peaks were found to decrease and broaden with increasing variation in the period length and disappeared completely in samples with up to 10 % variation. Thermal conductivity measurements performed using an optical pump-probe technique showed lower thermal conductivities for samples with greater variation. The irregularity of the superlattice period is believed to enhance the structure's ability to impede phonon propagation.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>