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Non-linear Effects in Gallium Nitride Acoustic Resonators

Vikrant J. Gokahle

Sponsor: National Science Foundation National Science Foundation

An interesting phenomenon we are exploring is the acoustoelectric effect in Gallium Nitride. The acoustoelectric effect is due to interactions of electron and phonons in semiconductors. Using this effect phonon-electron energy from an applied DC voltage reduces (or can even cancel) the material loss due to phonon-phonon interactions, resulting in improved Q in a GaN resonator or filter. We reported the first measured results for this effect in GaN, manifested as an amplification of the Q in thickness-mode filters. This effect makes it possible to tune the Q and bandwidth of GaN resonators and filters by applying a DC voltage. We intend to explore the fundamental nature of this effect, and its utility in GaN based electronic and mechanical systems. As an application, we plan to utilize the acoustoelectric effect to improve the Q and increase the sensitivity of the IR detector. We are also exploring other non-linear effects in GaN that result in changes in its acoustic properties.

V. J. Gokhale, Y. Shim, and M. Rais-Zadeh, "Observation of the acoustoelectric effect in Gallium Nitride micromechanical bulk acoustic filters," Frequency Control Symposium, 2010 IEEE International, Newport Beach, California, June 2010.

V. J. Gokhale, Y. Shim, V.A. Thakar, and M. Rais-Zadeh, "Q amplification in Gallium Nitride thickness-mode filters using acoustoelectric effect," Tech. Dig. Solid-State Sensors, Actuators, and Microsystems Workshop, Hilton Head Island, SC, June 2010.

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