{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/31007"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/31007","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Thermoelectric properties of polysilicon inverse opals","abstract":"Nanostructured single-crystal silicon exhibits a remarkable increase in the gure of merit for thermoelectric energy conversion. Here we theoretically and experimentally(partial) investigate a similar enhancement for polycrystalline silicon structured as an inverse opal. An inverse opal provides nanoscale grains and a thin- lm like geometry to scatter phonons preferentially over electrons. Using solutions to the Boltzmann transport equation for electrons and phonons, we show that the gure of merit at 300 K is fteen times that of bulk single-crystal silicon. Our models predict that grain boundaries are more e ective than surfaces in enhancing the figure of merit. We provide insight into this e ect and show that preserving a grain size smaller than the shell thickness of the inverse opal increases the gure of merit by as much as 50% when the ratio between the two features is a third. At 600 K, the figure of merit is as high as 0.6 for a shell thickness of 10 nm. We also measured the thermal conductivity of such nanostructures, and a more accurate thermal transport model is provided based on the experimental results.","abstract_html":"Nanostructured single-crystal silicon exhibits a remarkable increase in the gure of merit for thermoelectric energy conversion. Here we theoretically and experimentally(partial) investigate a similar enhancement for polycrystalline silicon structured as an inverse opal. An inverse opal provides nanoscale grains and a thin- lm like geometry to scatter phonons preferentially over electrons. Using solutions to the Boltzmann transport equation for electrons and phonons, we show that the gure of merit at 300 K is fteen times that of bulk single-crystal silicon. Our models predict that grain boundaries are more e ective than surfaces in enhancing the figure of merit. We provide insight into this e ect and show that preserving a grain size smaller than the shell thickness of the inverse opal increases the gure of merit by as much as 50% when the ratio between the two features is a third. At 600 K, the figure of merit is as high as 0.6 for a shell thickness of 10 nm. We also measured the thermal conductivity of such nanostructures, and a more accurate thermal transport model is provided based on the experimental results.","abstract_has_math":false,"creators":["Ma, Jun"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Sinha, Sanjiv"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-05-22T00:21:13Z","date_published":"2012-05-22T00:21:13Z","updated_at":"2026-07-22T22:25:29Z","subjects":["Thermoelectrics","Inverse opal"],"languages":["en"],"rights":["Copyright 2012 Jun Ma"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/31007","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Sinha, Sanjiv"]},{"key":"dc:creator","label":"Author","values":["Ma, Jun"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-05-22T00:21:13Z","2012-05"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Thermoelectrics","Inverse opal"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2012 Jun Ma"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/31007"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Nanostructured single-crystal silicon exhibits a remarkable increase in the gure of merit for thermoelectric energy conversion. Here we theoretically and experimentally(partial) investigate a similar enhancement for polycrystalline silicon structured as an inverse opal. An inverse opal provides nanoscale grains and a thin- lm like geometry to scatter phonons preferentially over electrons. Using solutions to the Boltzmann transport equation for electrons and phonons, we show that the gure of merit at 300 K is fteen times that of bulk single-crystal silicon. Our models predict that grain boundaries are more e ective than surfaces in enhancing the figure of merit. We provide insight into this e ect and show that preserving a grain size smaller than the shell thickness of the inverse opal increases the gure of merit by as much as 50% when the ratio between the two features is a third. At 600 K, the figure of merit is as high as 0.6 for a shell thickness of 10 nm. We also measured the thermal conductivity of such nanostructures, and a more accurate thermal transport model is provided based on the experimental results.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-04-21T16:31:31Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Ma_Jun.pdf: 1958280 bytes, checksum: 7725536eeed32fb7f60197ea8e915d2b (MD5)","Made available in DSpace on 2012-05-22T00:21:13Z (GMT). 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Our models predict that grain boundaries are more e ective than surfaces in enhancing the figure of merit. We provide insight into this e ect and show that preserving a grain size smaller than the shell thickness of the inverse opal increases the gure of merit by as much as 50% when the ratio between the two features is a third. At 600 K, the figure of merit is as high as 0.6 for a shell thickness of 10 nm. We also measured the thermal conductivity of such nanostructures, and a more accurate thermal transport model is provided based on the experimental results.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-04-21T16:31:31Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Ma_Jun.pdf: 1958280 bytes, checksum: 7725536eeed32fb7f60197ea8e915d2b (MD5)","Made available in DSpace on 2012-05-22T00:21:13Z (GMT). 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