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Effect of Externally-Imposed Radial Strain on the Piezoelectric Response of MOCVD-Grown Gallium Nitride

Published online by Cambridge University Press:  17 March 2011

Jennifer A. Himes ,
James R. Willis  and
Daniel A. Gulino
Jennifer A. Himes
Affiliation:
Department of Chemical Engineering and Condensed Matter and Surface Science ProgramOhio UniversityAthens, OH 45701
James R. Willis
Affiliation:
Department of Chemical Engineering and Condensed Matter and Surface Science ProgramOhio UniversityAthens, OH 45701
Daniel A. Gulino
Affiliation:
Department of Chemical Engineering and Condensed Matter and Surface Science ProgramOhio UniversityAthens, OH 45701
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Abstract

The large piezoelectric constants of GaN suggest possible application of GaN-based materials in piezoelectric sensors, among other areas. GaN's wide band gap implies that these sensors will fare well over a broad temperature range and/or in a harsh environment.

In this work, films of gallium nitride approximately 0.75 micron thick and grown by MOCVD were subject to an externally-imposed radial stress condition. Deposition was performed in a commercial MOCVD reactor (CVD, Inc.) at 1323K using trimethylgallium and ammonia as the chemical precursors. The substrate was one-inch diameter silicon (111). After deposition, titanium dots were deposited in various locations, including the wafer center, by evaporation. Stress was applied to the film/substrate system using a modified micrometer head (Mitutoyo) mounted to an Ionic Systems Basic Stressgauge (model 30285). Stress levels were calculated based on the magnitude of the imposed deflection as read from the micrometer head display, and the piezoelectric response at any particular dot with respect to the center dot was measured by measuring the voltage difference using a digital multimeter (Keithley 175). The micrometer head impinged on the center dot and served as one electrical contact point.

Effective piezoelectric coefficients were measured as a function of imposed radial stress. Applied stresses in the range of 1 to 5 GPa resulted in effective piezoelectric coefficients ranging from –0.6 to –2.0 × 10-5 C/m2

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 639: Symposium G – GaN and Related Alloys-2000 , 2000 , G11.58
Copyright
Copyright © Materials Research Society 2001

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References

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