Improvement of Ohmic contacts on Ga2O3 through use of ITO-interlayers

• Published in: Journal of vacuum science and technology. B, Nanotechnology & microelectronics Vol. 35; no. 6
• Main Authors: Carey, Patrick H., Yang, Jiancheng, Ren, Fan, Hays, David C., Pearton, Stephen J., Kuramata, Akito, Kravchenko, Ivan I.
• Format: Journal Article
• Language: English
• Published: United States American Vacuum Society/AIP 01.11.2017
• Subjects: CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; MATERIALS SCIENCE
• ISSN: 2166-2746; 2166-2754
• DOI: 10.1116/1.4995816

The use of ITO interlayers between Ga2O3 and Ti/Au metallization is shown to produce Ohmic contacts after annealing in the range of 500–600 °C. Without the ITO, similar anneals do not lead to linear current–voltage characteristics. Transmission line measurements were used to extract the specific contact resistance of the Au/Ti/ITO/Ga2O3 stacks as a function of annealing temperature. Sheet, specific contact, and transfer resistances all decreased sharply from as-deposited values with annealing. The minimum transfer resistance and specific contact resistance of 0.60 Ω mm and 6.3 × 10−5 Ω cm2 were achieved after 600 °C annealing, respectively. The conduction band offset between ITO and Ga2O3 is 0.32 eV and is consistent with the improved electron transport across the heterointerface.