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oai:www.ideals.illinois.edu:2142/14559 2023-07-10 col_2142_5131 col_2142_8888 com_2142_5130 com_2142_8887 com_2142_234

Adesida, Ilesanmi Adesida, Ilesanmi Schutt-Ainé, José E. Hsieh, Kuang-Chien Ravaioli, Umberto Ofuonye, Benedict Chukwuka 2010-01-06T16:12:07Z 2010-01-06T16:12:07Z 2010-01-06T16:12:07Z 2009-12 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 Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2009-10-19T21:03:05Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: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) http://hdl.handle.net/2142/14559 en copyright 2009 Benedict Chukwuka Ofuonye AlGaN/GAN Implantation Contacts Schottky Ohmic Thermal Annealing Stability Self-aligned Gallium Nitride (GaN) Activation Selective-Area Metallization Advanced process development for contacts to algan/gan high electron mobility transistors (HEMTS) Electrical & Computer Eng 1933 Electrical & Computer Engr 1200 University of Illinois at Urbana-Champaign Dissertation Ph.D. PHD:Electr & Computer Eng-UIUC 10KS1200PHD