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Characterization and Reliability of Vertical N-Type Gallium Nitride Schottky Contacts

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Technical Report

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Naval Postgraduate School Monterey United States

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Silicon- and silicon carbide-based power devices have dominated the power electronics industry. Formany emerging high-current and high-power applications, vertical transport gallium nitride GaN-baseddevices are more desirable. In this study, a series of reduced-defect, vertical n-type GaN Schottky contactswere fabricated and subjected to high-current density accelerated lifetime tests to understand the physics ofcontact degradation and compare the reliability of different metallization types and process cleans. TestedSchottky metals included molybdenum, molybdenum-gold, and chromium-gold. Process cleans comparedwere a piranha etch and a hydrofluoric acid etch. Pre-stress electrical characterization confirmedfunctioning Schottky contacts and determined device electrical performance parameters. Using a stress-measure-stress system, we obtained results of high-current density accelerated lifetime testing of 170 hoursat current densities of 2.3 kAcm-2 that showed both catastrophic and non-catastrophic failures across allmetallization types and process cleans. While comparative analysis showed that molybdenum was themost reliable, identified experimental testing and non-ideal fabrication issues limited the conclusivity ofthe results. The identified constraints and initial comparative results serve to inform future Schottkycontact structural design and fabrication for future optimized testing.

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  • Electrical and Electronic Equipment
  • Inorganic Chemistry

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