{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/82778"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/82778","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Thermal Transport on the Nanometer Scale and the Effect of Microstructure and Interface Resistance","abstract":"The aim of this research is to provide a better understanding of the physics of phonons involved in thermal transport on nanometer scale and to address the need for systematic information about the thermal properties of ultra-thin films. The present work includes data on thermal transport in dense and porous hydrogen silsesquioxane thin films and thin SiO2 films, across TiN/MgO(001), TiN/MgO(111) and TiN/Al2O3(0001), and in W/Al2O3, Re/Al2O3 and W/B multilayers. The thermal conductivities of low-k dielectric thin films were measured with the 3o method between 80 and 400 K. The strong temperature dependence is not reflected by the minimum thermal conductivity model for homogeneous materials. The differential effective medium model predicts a 1.5 power scaling of thermal conductivity with atomic density, in good agreement with experimental data. The thermal conductances G of TiN/MgO(001), TiN/MgO(111) and TiN/Al2O3(0001), interfaces, measured at temperatures between 79.4 and 294 K using time-domain thermoreflectance, are essentially identical and in good agreement with the predictions of lattice dynamics models and the diffuse mismatch model. Near room temperature G ≈ 700 MW m-2 K-1, ≈5 times larger than the highest values reported previously for any individual interface. For W/Al2O3, multilayers deposited by atomic layer deposition with layers only a few nanometers thick, the high interface density produced a strong impediment to heat transfer, giving a thermal conductivity of ∼0.6 W m-1 K-1. The thermal conductivities of magnetron sputtered multilayers of W/Al2O3, Re/Al 2O3 and W/B decrease with increasing number of layers and the dependence on temperature is similar to that predicted by the diffuse mismatch model. The conductivities of W/Al2O3, and Re/Al 2O3 multilayers were found to be similar, and as low as ∼0.6 W m-1 K-1---suitable for ultra-low conductivity thermal barriers.","abstract_html":"The aim of this research is to provide a better understanding of the physics of phonons involved in thermal transport on nanometer scale and to address the need for systematic information about the thermal properties of ultra-thin films. The present work includes data on thermal transport in dense and porous hydrogen silsesquioxane thin films and thin SiO2 films, across TiN/MgO(001), TiN/MgO(111) and TiN/Al2O3(0001), and in W/Al2O3, Re/Al2O3 and W/B multilayers. The thermal conductivities of low-k dielectric thin films were measured with the 3o method between 80 and 400 K. The strong temperature dependence is not reflected by the minimum thermal conductivity model for homogeneous materials. The differential effective medium model predicts a 1.5 power scaling of thermal conductivity with atomic density, in good agreement with experimental data. The thermal conductances G of TiN/MgO(001), TiN/MgO(111) and TiN/Al2O3(0001), interfaces, measured at temperatures between 79.4 and 294 K using time-domain thermoreflectance, are essentially identical and in good agreement with the predictions of lattice dynamics models and the diffuse mismatch model. Near room temperature G ≈ 700 MW m-2 K-1, ≈5 times larger than the highest values reported previously for any individual interface. For W/Al2O3, multilayers deposited by atomic layer deposition with layers only a few nanometers thick, the high interface density produced a strong impediment to heat transfer, giving a thermal conductivity of ∼0.6 W m-1 K-1. The thermal conductivities of magnetron sputtered multilayers of W/Al2O3, Re/Al 2O3 and W/B decrease with increasing number of layers and the dependence on temperature is similar to that predicted by the diffuse mismatch model. The conductivities of W/Al2O3, and Re/Al 2O3 multilayers were found to be similar, and as low as ∼0.6 W m-1 K-1---suitable for ultra-low conductivity thermal barriers.","abstract_has_math":false,"creators":["Costescu, Ruxandra M."],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Materials Science and Engineering","degree_department":null,"school":null,"contributors":["David Cahill"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-09-25T20:52:59Z","date_published":"2015-09-25T20:52:59Z","updated_at":"2026-07-22T22:26:18Z","subjects":["Engineering, Materials Science"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(MiAaPQ)AAI3223572"],"render_values":[{"text":"(MiAaPQ)AAI3223572","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/82778","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["David Cahill"]},{"key":"dc:creator","label":"Author","values":["Costescu, Ruxandra M."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-09-25T20:52:59Z","10000-01-01","2006"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Science and Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"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":["Engineering, Materials Science"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/82778","(MiAaPQ)AAI3223572"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The aim of this research is to provide a better understanding of the physics of phonons involved in thermal transport on nanometer scale and to address the need for systematic information about the thermal properties of ultra-thin films. The present work includes data on thermal transport in dense and porous hydrogen silsesquioxane thin films and thin SiO2 films, across TiN/MgO(001), TiN/MgO(111) and TiN/Al2O3(0001), and in W/Al2O3, Re/Al2O3 and W/B multilayers. The thermal conductivities of low-k dielectric thin films were measured with the 3o method between 80 and 400 K. The strong temperature dependence is not reflected by the minimum thermal conductivity model for homogeneous materials. The differential effective medium model predicts a 1.5 power scaling of thermal conductivity with atomic density, in good agreement with experimental data. The thermal conductances G of TiN/MgO(001), TiN/MgO(111) and TiN/Al2O3(0001), interfaces, measured at temperatures between 79.4 and 294 K using time-domain thermoreflectance, are essentially identical and in good agreement with the predictions of lattice dynamics models and the diffuse mismatch model. Near room temperature G ≈ 700 MW m-2 K-1, ≈5 times larger than the highest values reported previously for any individual interface. For W/Al2O3, multilayers deposited by atomic layer deposition with layers only a few nanometers thick, the high interface density produced a strong impediment to heat transfer, giving a thermal conductivity of ∼0.6 W m-1 K-1. The thermal conductivities of magnetron sputtered multilayers of W/Al2O3, Re/Al 2O3 and W/B decrease with increasing number of layers and the dependence on temperature is similar to that predicted by the diffuse mismatch model. The conductivities of W/Al2O3, and Re/Al 2O3 multilayers were found to be similar, and as low as ∼0.6 W m-1 K-1---suitable for ultra-low conductivity thermal barriers.","Made available in DSpace on 2015-09-25T20:52:59Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3223572.pdf: 2535054 bytes, checksum: 8e5d577130fbe403ad916251143a4f98 (MD5) Previous issue date: 2006","Embargo set by: Seth Robbins for item 84059 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","94 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006."]},{"key":"dc:title","label":"Title","values":["Thermal Transport on the Nanometer Scale and the Effect of Microstructure and Interface Resistance"]}]}],"canonical_facts":{"dc:contributor":["David Cahill"],"dc:creator":["Costescu, Ruxandra M."],"dc:date":["2015-09-25T20:52:59Z","10000-01-01","2006"],"dc:description":["The aim of this research is to provide a better understanding of the physics of phonons involved in thermal transport on nanometer scale and to address the need for systematic information about the thermal properties of ultra-thin films. The present work includes data on thermal transport in dense and porous hydrogen silsesquioxane thin films and thin SiO2 films, across TiN/MgO(001), TiN/MgO(111) and TiN/Al2O3(0001), and in W/Al2O3, Re/Al2O3 and W/B multilayers. The thermal conductivities of low-k dielectric thin films were measured with the 3o method between 80 and 400 K. The strong temperature dependence is not reflected by the minimum thermal conductivity model for homogeneous materials. The differential effective medium model predicts a 1.5 power scaling of thermal conductivity with atomic density, in good agreement with experimental data. The thermal conductances G of TiN/MgO(001), TiN/MgO(111) and TiN/Al2O3(0001), interfaces, measured at temperatures between 79.4 and 294 K using time-domain thermoreflectance, are essentially identical and in good agreement with the predictions of lattice dynamics models and the diffuse mismatch model. Near room temperature G ≈ 700 MW m-2 K-1, ≈5 times larger than the highest values reported previously for any individual interface. For W/Al2O3, multilayers deposited by atomic layer deposition with layers only a few nanometers thick, the high interface density produced a strong impediment to heat transfer, giving a thermal conductivity of ∼0.6 W m-1 K-1. The thermal conductivities of magnetron sputtered multilayers of W/Al2O3, Re/Al 2O3 and W/B decrease with increasing number of layers and the dependence on temperature is similar to that predicted by the diffuse mismatch model. The conductivities of W/Al2O3, and Re/Al 2O3 multilayers were found to be similar, and as low as ∼0.6 W m-1 K-1---suitable for ultra-low conductivity thermal barriers.","Made available in DSpace on 2015-09-25T20:52:59Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3223572.pdf: 2535054 bytes, checksum: 8e5d577130fbe403ad916251143a4f98 (MD5) Previous issue date: 2006","Embargo set by: Seth Robbins for item 84059 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","94 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006."],"dc:identifier":["http://hdl.handle.net/2142/82778","(MiAaPQ)AAI3223572"],"dc:language":["eng"],"dc:subject":["Engineering, Materials Science"],"dc:title":["Thermal Transport on the Nanometer Scale and the Effect of Microstructure and Interface Resistance"],"dc:type":["text"],"thesis:degree_discipline":["Materials Science and Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:18Z"}