{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/14559"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/14559","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Advanced process development for contacts to algan/gan high electron mobility transistors (HEMTS)","abstract":"High work function metals--Ni, Pt, Ir, and Au--were comparatively studied as Schottky metallizations to GaN and AlGaN/GaN heterostructures. Ni/Au, Ni/Pt/Au, Ir/Au, Ir/Pt/Au and Pt/Au Schottky diodes were fabricated on GaN and AlGaN/GaN substrates. Schottky barrier heights ranging from 0.8 to 0.9 eV were obtained as-deposited on GaN with ideality factors of about 1.05. The quality of the Schottky diodes was evaluated and their thermal stability also was studied. The interposition of Pt in Ni/Au and Ir/Au systems was found to improve the characteristics of the Schottky diodes. Ir/Pt/Au diodes were found to be more thermally stable than Ni/Pt/Au diodes. Ni/Au Schottky contacts exhibited good leakage response under thermal annealing for long periods. Microstructural studies were carried out on Ni/Pt/Au and Ni/Au Schottky contacts to elucidate the role of the intermediate layer, Pt, in the degradation of the Ni/Pt/Au metallization under long-term thermal anneal. A selective-area silicon ion implantation process for ohmic contact resistance improvement to AlGaN/GaN high electron mobility transistors (HEMTs) was developed. Non-alloyed ohmic contacts with very low contact resistances of 0.2 - 0.24 -mm were achieved with TLM pads fabricated using the Mo/Al/Mo/Au metallization. Simulations were carried out with SRIM to qualify the implantation process. Surface chemistry analysis was undertaken on the implanted AlGaN/GaN and GaN samples to determine the impact of implantation on the surface morphology of the AlGaN layer. The developed ion-implantation process was used to propose fabrication schemes for novel high speed self-aligned and non-self-aligned AlGaN/GaN high electron mobility trasistors (HEMTs) employing Ir/Pt/Au or Ni/Au gate and non-alloyed ohmic contact metallizations.","abstract_html":"High work function metals--Ni, Pt, Ir, and Au--were comparatively studied as Schottky metallizations to GaN and AlGaN/GaN heterostructures. Ni/Au, Ni/Pt/Au, Ir/Au, Ir/Pt/Au and Pt/Au Schottky diodes were fabricated on GaN and AlGaN/GaN substrates. Schottky barrier heights ranging from 0.8 to 0.9 eV were obtained as-deposited on GaN with ideality factors of about 1.05. The quality of the Schottky diodes was evaluated and their thermal stability also was studied. The interposition of Pt in Ni/Au and Ir/Au systems was found to improve the characteristics of the Schottky diodes. Ir/Pt/Au diodes were found to be more thermally stable than Ni/Pt/Au diodes. Ni/Au Schottky contacts exhibited good leakage response under thermal annealing for long periods. Microstructural studies were carried out on Ni/Pt/Au and Ni/Au Schottky contacts to elucidate the role of the intermediate layer, Pt, in the degradation of the Ni/Pt/Au metallization under long-term thermal anneal. A selective-area silicon ion implantation process for ohmic contact resistance improvement to AlGaN/GaN high electron mobility transistors (HEMTs) was developed. Non-alloyed ohmic contacts with very low contact resistances of 0.2 - 0.24 -mm were achieved with TLM pads fabricated using the Mo/Al/Mo/Au metallization. Simulations were carried out with SRIM to qualify the implantation process. Surface chemistry analysis was undertaken on the implanted AlGaN/GaN and GaN samples to determine the impact of implantation on the surface morphology of the AlGaN layer. The developed ion-implantation process was used to propose fabrication schemes for novel high speed self-aligned and non-self-aligned AlGaN/GaN high electron mobility trasistors (HEMTs) employing Ir/Pt/Au or Ni/Au gate and non-alloyed ohmic contact metallizations.","abstract_has_math":false,"creators":["Ofuonye, Benedict Chukwuka"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Adesida, Ilesanmi","Schutt-Ainé, José E.","Hsieh, Kuang-Chien","Ravaioli, Umberto"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010-01-06T16:12:07Z","date_published":"2010-01-06T16:12:07Z","updated_at":"2026-07-22T22:25:07Z","subjects":["AlGaN/GAN","Implantation","Contacts","Schottky","Ohmic","Thermal Annealing","Stability","Self-aligned","Gallium Nitride (GaN)","Activation","Selective-Area","Metallization"],"languages":["en"],"rights":["copyright 2009 Benedict Chukwuka Ofuonye"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/14559","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Adesida, Ilesanmi","Schutt-Ainé, José E.","Hsieh, Kuang-Chien","Ravaioli, Umberto"]},{"key":"dc:creator","label":"Author","values":["Ofuonye, Benedict Chukwuka"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2010-01-06T16:12:07Z","2009-12"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical & Computer 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":["AlGaN/GAN","Implantation","Contacts","Schottky","Ohmic","Thermal Annealing","Stability","Self-aligned","Gallium Nitride (GaN)","Activation","Selective-Area","Metallization"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["copyright 2009 Benedict Chukwuka Ofuonye"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/14559"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["High work function metals--Ni, Pt, Ir, and Au--were comparatively studied as Schottky metallizations to GaN and AlGaN/GaN heterostructures. Ni/Au, Ni/Pt/Au, Ir/Au, Ir/Pt/Au and Pt/Au Schottky diodes were fabricated on GaN and AlGaN/GaN substrates. Schottky barrier heights ranging from 0.8 to 0.9 eV were obtained as-deposited on GaN with ideality factors of about 1.05. The quality of the Schottky diodes was evaluated and their thermal stability also was studied. The interposition of Pt in Ni/Au and Ir/Au systems was found to improve the characteristics of the Schottky diodes. Ir/Pt/Au diodes were found to be more thermally stable than Ni/Pt/Au diodes. Ni/Au Schottky contacts exhibited good leakage response under thermal annealing for long periods. Microstructural studies were carried out on Ni/Pt/Au and Ni/Au Schottky contacts to elucidate the role of the intermediate layer, Pt, in the degradation of the Ni/Pt/Au metallization under long-term thermal anneal. A selective-area silicon ion implantation process for ohmic contact resistance improvement to AlGaN/GaN high electron mobility transistors (HEMTs) was developed. Non-alloyed ohmic contacts with very low contact resistances of 0.2 - 0.24 -mm were achieved with TLM pads fabricated using the Mo/Al/Mo/Au metallization. Simulations were carried out with SRIM to qualify the implantation process. Surface chemistry analysis was undertaken on the implanted AlGaN/GaN and GaN samples to determine the impact of implantation on the surface morphology of the AlGaN layer. The developed ion-implantation process was used to propose fabrication schemes for novel high speed self-aligned and non-self-aligned AlGaN/GaN high electron mobility trasistors (HEMTs) employing Ir/Pt/Au or Ni/Au gate and non-alloyed ohmic contact metallizations.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2009-10-19T21:03:05Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Ofuonye_Benedict.pdf: 18837531 bytes, checksum: 24021840e0f6c2a87517b1d3b109b626 (MD5)","Made available in DSpace on 2010-01-06T16:12:07Z (GMT). No. of bitstreams: 4 license.txt: 4066 bytes, checksum: abfd512f8d29786b4ae75ad6d32fa691 (MD5) Ofuonye_Benedict.pdf: 18837650 bytes, checksum: fe4ca0c8456b6e6f9fb8078b549ea708 (MD5) 1_Ofuonye_Benedict.pdf: 18837531 bytes, checksum: 24021840e0f6c2a87517b1d3b109b626 (MD5) 2_Ofuonye_Benedict.pdf: 18837518 bytes, checksum: 0837fba26ed00057eba10c473f401f11 (MD5)"]},{"key":"dc:title","label":"Title","values":["Advanced process development for contacts to algan/gan high electron mobility transistors (HEMTS)"]}]}],"canonical_facts":{"dc:contributor":["Adesida, Ilesanmi","Schutt-Ainé, José E.","Hsieh, Kuang-Chien","Ravaioli, Umberto"],"dc:creator":["Ofuonye, Benedict Chukwuka"],"dc:date":["2010-01-06T16:12:07Z","2009-12"],"dc:description":["High work function metals--Ni, Pt, Ir, and Au--were comparatively studied as Schottky metallizations to GaN and AlGaN/GaN heterostructures. Ni/Au, Ni/Pt/Au, Ir/Au, Ir/Pt/Au and Pt/Au Schottky diodes were fabricated on GaN and AlGaN/GaN substrates. Schottky barrier heights ranging from 0.8 to 0.9 eV were obtained as-deposited on GaN with ideality factors of about 1.05. The quality of the Schottky diodes was evaluated and their thermal stability also was studied. The interposition of Pt in Ni/Au and Ir/Au systems was found to improve the characteristics of the Schottky diodes. Ir/Pt/Au diodes were found to be more thermally stable than Ni/Pt/Au diodes. Ni/Au Schottky contacts exhibited good leakage response under thermal annealing for long periods. Microstructural studies were carried out on Ni/Pt/Au and Ni/Au Schottky contacts to elucidate the role of the intermediate layer, Pt, in the degradation of the Ni/Pt/Au metallization under long-term thermal anneal. A selective-area silicon ion implantation process for ohmic contact resistance improvement to AlGaN/GaN high electron mobility transistors (HEMTs) was developed. Non-alloyed ohmic contacts with very low contact resistances of 0.2 - 0.24 -mm were achieved with TLM pads fabricated using the Mo/Al/Mo/Au metallization. Simulations were carried out with SRIM to qualify the implantation process. Surface chemistry analysis was undertaken on the implanted AlGaN/GaN and GaN samples to determine the impact of implantation on the surface morphology of the AlGaN layer. The developed ion-implantation process was used to propose fabrication schemes for novel high speed self-aligned and non-self-aligned AlGaN/GaN high electron mobility trasistors (HEMTs) employing Ir/Pt/Au or Ni/Au gate and non-alloyed ohmic contact metallizations.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2009-10-19T21:03:05Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Ofuonye_Benedict.pdf: 18837531 bytes, checksum: 24021840e0f6c2a87517b1d3b109b626 (MD5)","Made available in DSpace on 2010-01-06T16:12:07Z (GMT). No. of bitstreams: 4 license.txt: 4066 bytes, checksum: abfd512f8d29786b4ae75ad6d32fa691 (MD5) Ofuonye_Benedict.pdf: 18837650 bytes, checksum: fe4ca0c8456b6e6f9fb8078b549ea708 (MD5) 1_Ofuonye_Benedict.pdf: 18837531 bytes, checksum: 24021840e0f6c2a87517b1d3b109b626 (MD5) 2_Ofuonye_Benedict.pdf: 18837518 bytes, checksum: 0837fba26ed00057eba10c473f401f11 (MD5)"],"dc:identifier":["http://hdl.handle.net/2142/14559"],"dc:language":["en"],"dc:rights":["copyright 2009 Benedict Chukwuka Ofuonye"],"dc:subject":["AlGaN/GAN","Implantation","Contacts","Schottky","Ohmic","Thermal Annealing","Stability","Self-aligned","Gallium Nitride (GaN)","Activation","Selective-Area","Metallization"],"dc:title":["Advanced process development for contacts to algan/gan high electron mobility transistors (HEMTS)"],"thesis:degree_discipline":["Electrical & Computer Engr"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:07Z"}