Characterization and reliability of vertical n-type gallium nitride Schottky contacts
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Authors
Gardner, Michael L.
Subjects
accelerated lifetime testing
Schottky barrier height inhomogeneity
gallium nitride
vertical transport
power electronics
high current density
semiconductor reliability
Schottky barrier height inhomogeneity
gallium nitride
vertical transport
power electronics
high current density
semiconductor reliability
Advisors
Weatherford, Todd R.
Date of Issue
2016-09
Date
Sep-16
Publisher
Monterey, California: Naval Postgraduate School
Language
Abstract
Silicon- and silicon carbide-based power devices have dominated the power electronics industry. For many emerging high-current and high-power applications, vertical transport gallium nitride (GaN)-based devices are more desirable. In this study, a series of reduced-defect, vertical n-type GaN Schottky contacts were fabricated and subjected to high-current density accelerated lifetime tests to understand the physics of contact degradation and compare the reliability of different metallization types and process cleans. Tested Schottky metals included molybdenum, molybdenum-gold, and chromium-gold. Process cleans compared were a piranha etch and a hydrofluoric acid etch. Pre-stress electrical characterization confirmed functioning 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 hours at current densities of 2.3 kAcm-² that showed both catastrophic and non-catastrophic failures across all metallization types and process cleans. While comparative analysis showed that molybdenum was the most reliable, identified experimental testing and non-ideal fabrication issues limited the conclusivity of the results. The identified constraints and initial comparative results serve to inform future Schottky contact structural design and fabrication for future optimized testing
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Thesis
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Department
Electrical Engineering
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Distribution Statement
Approved for public release; distribution is unlimited.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.