CS ManTech Conference, May 16-19, 2016, Miami, Florida

Reliability Assessment of Thermally-Stable Gate Materials for AlGaN/GaN HEMTs

David I. Shahin1, Travis J. Anderson2, Jordan D. Greenlee2, Virginia D. Wheeler2, Marko J. Tadjer2, Bradford B. Pate2, Jennifer K. Hite2, Andrew D. Koehler2, Karl D. Hobart2, Charles R. Eddy Jr.2, Francis J. Kub2, and Aris Christou1
1 Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA
2 Naval Research Laboratory, Washington, DC 20375, USA


TiN and nanocrystalline diamond have been evaluated as potential replacements for conventional Nibased gate schemes in AlGaN/GaN HEMTs using reverse bias electrical stressing. TiN gates deposited by atomic layer deposition were found to be viable substitutes, as TiN-gated devices exhibited improved on-state characteristics in comparison to the Ni/Au-gated devices. TiN was also determined to have a much higher critical reverse gate voltage (Vgs = -210 V for TiN vs. -120 V for Ni/Au) at which gate degradation occurs. The TiN gates also catastrophically failed at slightly higher and much less variable breakdown voltages than the Ni/Au gates. Stressing at reverse gate biases slightly above the Ni/Au critical voltage but well below the TiN critical voltage (Vgs = -140 V) led to nearly an order of magnitude increase in leakage current for the Ni/Au, but decreased leakage in the TiN. Nanocrystalline diamond gates exhibited critical voltages of Vgs = -90 V and broke down at much lower reverse bias, possibly due to testing in air without encapsulation to protect the gate material.

This article is available to CALCE Consortium Members for personal review.

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