Effect of buckling on the thermal response of microelectromechanical beam resonators

We have investigated the thermal response of the doubly clamped microelectromechanical (MEMS) beam resonators as a function of an input heating power. When a small amount of heat (<1 mW) is applied to the MEMS beam, reduction in resonance frequency is observed. As the heating power is further increased, however, the resonance frequency levels off and starts to increase, which originates from the buckling of the beam. We find that the slope of the frequency increase at large input powers is 2-3 times steeper than that of the frequency decrease at small input powers and that the buckled device can take larger heating powers without degrading the linearity. These observations suggest that both the thermal sensitivity and the dynamic range can be improved by introducing a proper amount of buckling. Using this insight, we have fabricated a buckled MEMS beam resonator by using a strained InxGa1-xAs (x = 0.001) beam structure on a GaAs substrate. We have found that the frequency responsivity of the InxGa1-xAs beam sample is about 3 times higher than that of the GaAs beam sample, demonstrating that the introduction of buckling is useful for achieving higher thermal sensitivity for the MEMS beam resonators. Published by AIP Publishing.