{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/73047"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/73047","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Advanced purification of aligned arrays of single-walled carbon nanotubes","abstract":"The increasing difficulties for further scaling down of Si electronics are driving the investigation of alternative channel materials with higher energy efficiency and better performance. Among the large variety of semiconducting materials, single walled carbon nanotubes (SWNTs) are extremely attractive due to their outstanding charge transport properties and ultrathin bodies. One of the most daunting challenge, however, is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here, we present strategies to address this issue. Nanoscale thermocapillary flows and subsequent etching serve as an effective way to remove the metallic impurities in perfectly aligned arrays of SWNTs grown on quartz substrates. We develop a nanoscale thermometry-scanning Joule expansion microscopy (SJEM) for quantitative assessments of the low temperature nature associated with this process. Measurements combined with simulations fully reveal the essential physics of the thermocapillary flows. We also introduce a simple and scalable scheme to initiate the thermocapillary flows through microwave irradiation of SWNT arrays. Microstrip dipole antennas of low work function metals concentrate the microwaves and selectively couple them into only metallic SWNTs (m-SWNTs). Those efforts allow for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies. For a demonstration of the effectiveness, we implement this method on large arrays consisting of ~20,000 SWNTs, completely removing all of the m-SWNTs (~7000) to yield a purity of s-SWNTs at a level at least to 99.9925%. Lastly, we present several demonstrations of electronic and optoelectronic devices based on aligned arrays (both purified and unpurified) and detailed characterization of their performance.","abstract_html":"The increasing difficulties for further scaling down of Si electronics are driving the investigation of alternative channel materials with higher energy efficiency and better performance. Among the large variety of semiconducting materials, single walled carbon nanotubes (SWNTs) are extremely attractive due to their outstanding charge transport properties and ultrathin bodies. One of the most daunting challenge, however, is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here, we present strategies to address this issue. Nanoscale thermocapillary flows and subsequent etching serve as an effective way to remove the metallic impurities in perfectly aligned arrays of SWNTs grown on quartz substrates. We develop a nanoscale thermometry-scanning Joule expansion microscopy (SJEM) for quantitative assessments of the low temperature nature associated with this process. Measurements combined with simulations fully reveal the essential physics of the thermocapillary flows. We also introduce a simple and scalable scheme to initiate the thermocapillary flows through microwave irradiation of SWNT arrays. Microstrip dipole antennas of low work function metals concentrate the microwaves and selectively couple them into only metallic SWNTs (m-SWNTs). Those efforts allow for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies. For a demonstration of the effectiveness, we implement this method on large arrays consisting of ~20,000 SWNTs, completely removing all of the m-SWNTs (~7000) to yield a purity of s-SWNTs at a level at least to 99.9925%. Lastly, we present several demonstrations of electronic and optoelectronic devices based on aligned arrays (both purified and unpurified) and detailed characterization of their performance.","abstract_has_math":false,"creators":["Xie, Xu"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Materials Science & Engr","degree_department":null,"school":null,"contributors":["Rogers, John A.","Cahill, David G.","Braun, Paul V.","Lyding, Joseph W."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-01-21T19:58:51Z","date_published":"2015-01-21T19:58:51Z","updated_at":"2026-07-22T22:26:07Z","subjects":["Single walled carbon nanotubes (SWNT)","Aligned","Purification","Purity","Microwave","Electronics","Optoelectronics","Thermocapillary flows","Heating","Thermal"],"languages":["en"],"rights":["Copyright 2014 Xu Xie"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/73047","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Rogers, John A.","Cahill, David G.","Braun, Paul V.","Lyding, Joseph W."]},{"key":"dc:creator","label":"Author","values":["Xie, Xu"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-01-21T19:58:51Z","2017-01-22T10:15:37Z","2014-12","2015-01-21"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Science & Engr"]},{"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":["Single walled carbon nanotubes (SWNT)","Aligned","Purification","Purity","Microwave","Electronics","Optoelectronics","Thermocapillary flows","Heating","Thermal"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2014 Xu Xie"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/73047"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The increasing difficulties for further scaling down of Si electronics are driving the investigation of alternative channel materials with higher energy efficiency and better performance. Among the large variety of semiconducting materials, single walled carbon nanotubes (SWNTs) are extremely attractive due to their outstanding charge transport properties and ultrathin bodies. One of the most daunting challenge, however, is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here, we present strategies to address this issue. Nanoscale thermocapillary flows and subsequent etching serve as an effective way to remove the metallic impurities in perfectly aligned arrays of SWNTs grown on quartz substrates. We develop a nanoscale thermometry-scanning Joule expansion microscopy (SJEM) for quantitative assessments of the low temperature nature associated with this process. Measurements combined with simulations fully reveal the essential physics of the thermocapillary flows. We also introduce a simple and scalable scheme to initiate the thermocapillary flows through microwave irradiation of SWNT arrays. Microstrip dipole antennas of low work function metals concentrate the microwaves and selectively couple them into only metallic SWNTs (m-SWNTs). Those efforts allow for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies. For a demonstration of the effectiveness, we implement this method on large arrays consisting of ~20,000 SWNTs, completely removing all of the m-SWNTs (~7000) to yield a purity of s-SWNTs at a level at least to 99.9925%. Lastly, we present several demonstrations of electronic and optoelectronic devices based on aligned arrays (both purified and unpurified) and detailed characterization of their performance.","Item withdrawn by Laura Spradlin (lspradl2@illinois.edu) on 2014-11-07T22:20:39Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Xie_Xu.pdf.pdf: 5565083 bytes, checksum: a0117a21dd79ea5ce475eac33d3b5bd9 (MD5)","Made available in DSpace on 2015-01-21T19:58:51Z (GMT). No. of bitstreams: 1 Xu_Xie.pdf: 5565053 bytes, checksum: 823c61be96146c7f3389253cf0461f94 (MD5)","Embargo set by: Seth Robbins for item 73236 Lift date: 2017-01-21T19:59:39Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Limited Restriction Lifted for Item 73236 on 2017-01-22T10:15:37Z."]},{"key":"dc:title","label":"Title","values":["Advanced purification of aligned arrays of single-walled carbon nanotubes"]}]}],"canonical_facts":{"dc:contributor":["Rogers, John A.","Cahill, David G.","Braun, Paul V.","Lyding, Joseph W."],"dc:creator":["Xie, Xu"],"dc:date":["2015-01-21T19:58:51Z","2017-01-22T10:15:37Z","2014-12","2015-01-21"],"dc:description":["The increasing difficulties for further scaling down of Si electronics are driving the investigation of alternative channel materials with higher energy efficiency and better performance. Among the large variety of semiconducting materials, single walled carbon nanotubes (SWNTs) are extremely attractive due to their outstanding charge transport properties and ultrathin bodies. One of the most daunting challenge, however, is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here, we present strategies to address this issue. Nanoscale thermocapillary flows and subsequent etching serve as an effective way to remove the metallic impurities in perfectly aligned arrays of SWNTs grown on quartz substrates. We develop a nanoscale thermometry-scanning Joule expansion microscopy (SJEM) for quantitative assessments of the low temperature nature associated with this process. Measurements combined with simulations fully reveal the essential physics of the thermocapillary flows. We also introduce a simple and scalable scheme to initiate the thermocapillary flows through microwave irradiation of SWNT arrays. Microstrip dipole antennas of low work function metals concentrate the microwaves and selectively couple them into only metallic SWNTs (m-SWNTs). Those efforts allow for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies. For a demonstration of the effectiveness, we implement this method on large arrays consisting of ~20,000 SWNTs, completely removing all of the m-SWNTs (~7000) to yield a purity of s-SWNTs at a level at least to 99.9925%. Lastly, we present several demonstrations of electronic and optoelectronic devices based on aligned arrays (both purified and unpurified) and detailed characterization of their performance.","Item withdrawn by Laura Spradlin (lspradl2@illinois.edu) on 2014-11-07T22:20:39Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Xie_Xu.pdf.pdf: 5565083 bytes, checksum: a0117a21dd79ea5ce475eac33d3b5bd9 (MD5)","Made available in DSpace on 2015-01-21T19:58:51Z (GMT). No. of bitstreams: 1 Xu_Xie.pdf: 5565053 bytes, checksum: 823c61be96146c7f3389253cf0461f94 (MD5)","Embargo set by: Seth Robbins for item 73236 Lift date: 2017-01-21T19:59:39Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Limited Restriction Lifted for Item 73236 on 2017-01-22T10:15:37Z."],"dc:identifier":["http://hdl.handle.net/2142/73047"],"dc:language":["en"],"dc:rights":["Copyright 2014 Xu Xie"],"dc:subject":["Single walled carbon nanotubes (SWNT)","Aligned","Purification","Purity","Microwave","Electronics","Optoelectronics","Thermocapillary flows","Heating","Thermal"],"dc:title":["Advanced purification of aligned arrays of single-walled carbon nanotubes"],"dc:type":["text"],"thesis:degree_discipline":["Materials Science & Engr"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:07Z"}