{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/81312"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/81312","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Process Development and Characterization of AlGaN/GaN Heterostructure Field-Effect Transistors","abstract":"The fabrication of AlGaN/GaN HFETs entailed first developing fundamental processing techniques such as isolation etching, low-resistance drain/source ohmic contacts, and Schottky gate formation. These efforts along with related processing issues will be discussed. Devices were then fabricated on epitaxial layers grown on sapphire substrates and on n-type, p-type, and insulating SiC. While sapphire is the substrate of choice for the nitrides, SiC substrates are better suited for high-power devices due to their significantly higher thermal conductivity. The dc, RF, and high-temperature performance of transistors on sapphire and SiC were investigated to determine the performance similarities and differences between using the various substrates. Forming low-resistance ohmic contacts to the wide bandgap heterostructures is difficult and as a result limits the overall device performance. In an effort to improve drain-source contacts, gate recessing through the use of low-damage inductively coupled plasma reactive ion etching was pursued. A wet chemical etching process called photoelectrochemical etching was also investigated.","abstract_html":"The fabrication of AlGaN/GaN HFETs entailed first developing fundamental processing techniques such as isolation etching, low-resistance drain/source ohmic contacts, and Schottky gate formation. These efforts along with related processing issues will be discussed. Devices were then fabricated on epitaxial layers grown on sapphire substrates and on n-type, p-type, and insulating SiC. While sapphire is the substrate of choice for the nitrides, SiC substrates are better suited for high-power devices due to their significantly higher thermal conductivity. The dc, RF, and high-temperature performance of transistors on sapphire and SiC were investigated to determine the performance similarities and differences between using the various substrates. Forming low-resistance ohmic contacts to the wide bandgap heterostructures is difficult and as a result limits the overall device performance. In an effort to improve drain-source contacts, gate recessing through the use of low-damage inductively coupled plasma reactive ion etching was pursued. A wet chemical etching process called photoelectrochemical etching was also investigated.","abstract_has_math":false,"creators":["Ping, Andrew Taiann"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Electrical Engineering","degree_department":null,"school":null,"contributors":["Adesida, Ilesanmi"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-09-25T20:10:30Z","date_published":"2015-09-25T20:10:30Z","updated_at":"2026-07-22T22:26:16Z","subjects":["Engineering, Electronics and Electrical"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(MiAaPQ)AAI9953111"],"render_values":[{"text":"(MiAaPQ)AAI9953111","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/81312","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Adesida, Ilesanmi"]},{"key":"dc:creator","label":"Author","values":["Ping, Andrew Taiann"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-09-25T20:10:30Z","10000-01-01","1999"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical 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, Electronics and Electrical"]}]},{"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/2142/81312","(MiAaPQ)AAI9953111"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The fabrication of AlGaN/GaN HFETs entailed first developing fundamental processing techniques such as isolation etching, low-resistance drain/source ohmic contacts, and Schottky gate formation. These efforts along with related processing issues will be discussed. Devices were then fabricated on epitaxial layers grown on sapphire substrates and on n-type, p-type, and insulating SiC. While sapphire is the substrate of choice for the nitrides, SiC substrates are better suited for high-power devices due to their significantly higher thermal conductivity. The dc, RF, and high-temperature performance of transistors on sapphire and SiC were investigated to determine the performance similarities and differences between using the various substrates. Forming low-resistance ohmic contacts to the wide bandgap heterostructures is difficult and as a result limits the overall device performance. In an effort to improve drain-source contacts, gate recessing through the use of low-damage inductively coupled plasma reactive ion etching was pursued. A wet chemical etching process called photoelectrochemical etching was also investigated.","Made available in DSpace on 2015-09-25T20:10:30Z (GMT). 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These efforts along with related processing issues will be discussed. Devices were then fabricated on epitaxial layers grown on sapphire substrates and on n-type, p-type, and insulating SiC. While sapphire is the substrate of choice for the nitrides, SiC substrates are better suited for high-power devices due to their significantly higher thermal conductivity. The dc, RF, and high-temperature performance of transistors on sapphire and SiC were investigated to determine the performance similarities and differences between using the various substrates. Forming low-resistance ohmic contacts to the wide bandgap heterostructures is difficult and as a result limits the overall device performance. In an effort to improve drain-source contacts, gate recessing through the use of low-damage inductively coupled plasma reactive ion etching was pursued. 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