{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/106382"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/106382","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Metal-assisted chemical etching of β-gallium oxide","abstract":"β-Ga2O3, with an ultra-wide bandgap (UWB) of ~ 4.6 – 4.9 eV and bulk substrate availability, has drawn enormous interest in the power electronics community. Fabricating high-aspect-ratio β-Ga2O3 3D nanostructures without surface damage is essential for next-generation power electronics. Nonetheless, dry etch typically damages the surface due to high-energy ions, while most wet etching techniques can only produce very limited aspect ratios. In this thesis, β-Ga2O3 fin arrays by inverse metal-assisted chemical etching (MacEtch), under UV light irradiation, with a high aspect ratio and excellent surface quality, are demonstrated. The strongly crystal-orientation-dependent etching behaviors are found and three kinds of vertical structures are formed after the MacEtch process. The Schottky barrier heights (SBHs) between platinum (Pt) and different MacEtch-formed β-Ga2O3 surfaces and sidewalls are found to decrease as the aspect ratio of the β-Ga2O3 structure increases. This behavior is attributed to the varying oxygen composition on the surface after MacEtch, as shown by the XPS and TEM examination. Very little hysteresis has been observed in the capacitance-voltage characteristics of the 3D Pt/ Al2O3/ β-Ga2O3 MOS capacitor structures, and the lowest interface trap density extracted from etched interfaces is only 2.73×1011cm-2-eV-1, which is comparable to that of other published values of unetched β-Ga2O3 surfaces. This confirms that MacEtch is an effective etching method for producing high quality β-Ga2O3 3D structures.","abstract_html":"β-Ga2O3, with an ultra-wide bandgap (UWB) of ~ 4.6 – 4.9 eV and bulk substrate availability, has drawn enormous interest in the power electronics community. Fabricating high-aspect-ratio β-Ga2O3 3D nanostructures without surface damage is essential for next-generation power electronics. Nonetheless, dry etch typically damages the surface due to high-energy ions, while most wet etching techniques can only produce very limited aspect ratios. In this thesis, β-Ga2O3 fin arrays by inverse metal-assisted chemical etching (MacEtch), under UV light irradiation, with a high aspect ratio and excellent surface quality, are demonstrated. The strongly crystal-orientation-dependent etching behaviors are found and three kinds of vertical structures are formed after the MacEtch process. The Schottky barrier heights (SBHs) between platinum (Pt) and different MacEtch-formed β-Ga2O3 surfaces and sidewalls are found to decrease as the aspect ratio of the β-Ga2O3 structure increases. This behavior is attributed to the varying oxygen composition on the surface after MacEtch, as shown by the XPS and TEM examination. Very little hysteresis has been observed in the capacitance-voltage characteristics of the 3D Pt/ Al2O3/ β-Ga2O3 MOS capacitor structures, and the lowest interface trap density extracted from etched interfaces is only 2.73×1011cm-2-eV-1, which is comparable to that of other published values of unetched β-Ga2O3 surfaces. This confirms that MacEtch is an effective etching method for producing high quality β-Ga2O3 3D structures.","abstract_has_math":false,"creators":["Huang, Hsien-Chih"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Li, Xiuling"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-03-02T22:15:15Z","date_published":"2020-03-02T22:15:15Z","updated_at":"2026-07-22T22:24:45Z","subjects":["Metal-Assisted Chemical Etching, β-Ga2O3"],"languages":["en"],"rights":["Copyright 2019 Hsien-Chih Huang"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/106382","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Li, Xiuling"]},{"key":"dc:creator","label":"Author","values":["Huang, Hsien-Chih"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2020-03-02T22:15:15Z","2022-03-03T10:15:27Z","2019-12-10","2019-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical & Computer Engr"]},{"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":["Metal-Assisted Chemical Etching, β-Ga2O3"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2019 Hsien-Chih Huang"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/106382"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["β-Ga2O3, with an ultra-wide bandgap (UWB) of ~ 4.6 – 4.9 eV and bulk substrate availability, has drawn enormous interest in the power electronics community. Fabricating high-aspect-ratio β-Ga2O3 3D nanostructures without surface damage is essential for next-generation power electronics. Nonetheless, dry etch typically damages the surface due to high-energy ions, while most wet etching techniques can only produce very limited aspect ratios. In this thesis, β-Ga2O3 fin arrays by inverse metal-assisted chemical etching (MacEtch), under UV light irradiation, with a high aspect ratio and excellent surface quality, are demonstrated. The strongly crystal-orientation-dependent etching behaviors are found and three kinds of vertical structures are formed after the MacEtch process. The Schottky barrier heights (SBHs) between platinum (Pt) and different MacEtch-formed β-Ga2O3 surfaces and sidewalls are found to decrease as the aspect ratio of the β-Ga2O3 structure increases. This behavior is attributed to the varying oxygen composition on the surface after MacEtch, as shown by the XPS and TEM examination. Very little hysteresis has been observed in the capacitance-voltage characteristics of the 3D Pt/ Al2O3/ β-Ga2O3 MOS capacitor structures, and the lowest interface trap density extracted from etched interfaces is only 2.73×1011cm-2-eV-1, which is comparable to that of other published values of unetched β-Ga2O3 surfaces. This confirms that MacEtch is an effective etching method for producing high quality β-Ga2O3 3D structures.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-12-01","The student, Hsien-Chih Huang, accepted the attached license on 2019-12-06 at 16:24.","The student, Hsien-Chih Huang, submitted this Thesis for approval on 2019-12-06 at 16:30.","This Thesis was approved for publication on 2019-12-10 at 13:59.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14747 on 2020-02-28 at 17:23:52","Made available in DSpace on 2020-03-02T22:15:15Z (GMT). No. of bitstreams: 2 HUANG-THESIS-2019.pdf: 2316714 bytes, checksum: 5402c28e206d65ce54335a0da53e9ded (MD5) LICENSE.txt: 4213 bytes, checksum: 73198781f9d2b5d4a0656554a45e4e7c (MD5) Previous issue date: 2019-12-10","Embargo set by: Seth Robbins for item 113924 Lift date: 2022-03-02T22:15:21Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 113924 Lift date: 2022-03-02T22:18:25Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 113924 on 2022-03-03T10:15:27Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Metal-assisted chemical etching of β-gallium oxide"]}]}],"canonical_facts":{"dc:contributor":["Li, Xiuling"],"dc:creator":["Huang, Hsien-Chih"],"dc:date":["2020-03-02T22:15:15Z","2022-03-03T10:15:27Z","2019-12-10","2019-12"],"dc:description":["β-Ga2O3, with an ultra-wide bandgap (UWB) of ~ 4.6 – 4.9 eV and bulk substrate availability, has drawn enormous interest in the power electronics community. Fabricating high-aspect-ratio β-Ga2O3 3D nanostructures without surface damage is essential for next-generation power electronics. Nonetheless, dry etch typically damages the surface due to high-energy ions, while most wet etching techniques can only produce very limited aspect ratios. In this thesis, β-Ga2O3 fin arrays by inverse metal-assisted chemical etching (MacEtch), under UV light irradiation, with a high aspect ratio and excellent surface quality, are demonstrated. The strongly crystal-orientation-dependent etching behaviors are found and three kinds of vertical structures are formed after the MacEtch process. The Schottky barrier heights (SBHs) between platinum (Pt) and different MacEtch-formed β-Ga2O3 surfaces and sidewalls are found to decrease as the aspect ratio of the β-Ga2O3 structure increases. This behavior is attributed to the varying oxygen composition on the surface after MacEtch, as shown by the XPS and TEM examination. Very little hysteresis has been observed in the capacitance-voltage characteristics of the 3D Pt/ Al2O3/ β-Ga2O3 MOS capacitor structures, and the lowest interface trap density extracted from etched interfaces is only 2.73×1011cm-2-eV-1, which is comparable to that of other published values of unetched β-Ga2O3 surfaces. This confirms that MacEtch is an effective etching method for producing high quality β-Ga2O3 3D structures.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-12-01","The student, Hsien-Chih Huang, accepted the attached license on 2019-12-06 at 16:24.","The student, Hsien-Chih Huang, submitted this Thesis for approval on 2019-12-06 at 16:30.","This Thesis was approved for publication on 2019-12-10 at 13:59.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14747 on 2020-02-28 at 17:23:52","Made available in DSpace on 2020-03-02T22:15:15Z (GMT). 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