Thermoelastic damping in GaAs micromechanical resonators

Damping of the mechanical motion is one of the factors that limit the sensitivity of mechanical resonators. For the development of high-sensitivity transducers, it is important to understand the damping mechanism of the resonators and minimize the damping effect. Here, we show that the damping of a GaAs microcantilever strongly depends on the temperature and it is minimized at around 50 K. This temperature dependence of the damping is mainly caused by the thermoelastic damping effect, which is generated by the strain-induced temperature gradient in the GaAs cantilever. The minimization of the mechanical damping at around 50 K is due to the suppression of the thermal expansion of GaAs at this temperature, which eliminates the temperature gradient in the cantilever. This result indicates that the sensitivity of GaAs resonators can be improved by adjusting the operating temperature. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)