Colossal Modulation of Mechanical Resonance with temperature in single‐Crystalline SrTiO ₃ Microbridges Integrated on Silicon

ABSTRACT

Multifunctional oxides exhibit material properties that differ from yet complement those of conventional semiconductors. For nano/microelectromechanical systems, structural coupling between materials that exhibit dissimilar mechanical characteristics opens a pathway to realize novel functionalities. Here we present the structural characteristics and resonant mechanical behavior of suspended microbridges comprised of single‐crystalline SrTiO ₃ that has been epitaxially integrated on Si(100). While the epitaxial SrTiO ₃ is relaxed relative to the silicon substrate, residual tensile strain persists due to the difference in thermal expansion between the former and the latter. The strain in the SrTiO ₃ microbridges is inhomogeneous at the nanoscale due to the presence of extended defects associated with film relaxation. We find that the resonant frequencies of the microbridges are not only enhanced by the residual strain, but are also hyper‐sensitive to temperature, as quantified by exceptionally large temperature coefficients of frequency at room temperature. The “colossal” temperature coefficients of frequency potentially enable ultra‐sensitive, uncooled, infrared radiation sensors to be created.