Non-volatile tuning of mechanical resonance through applied mechanical stress in suspended BaTiO₃ micro-bridge resonators integrated on Si(100)

Deepa Guragain¹, Laveeza Ahmad², Xuanyi Zhang³, Matthew Chrysler¹, Richard Le¹, Jamal Brown¹, Zhan Zhang⁴, Divine P. Kumah³, Ye Cao², and Joseph H. Ngai<sup>1



1</sup>Department of Physics, University of Texas-Arlington, Arlington, TX 76019, USA

²Department of Materials Science & Engineering, University of Texas-Arlington, Arlington, TX 76019, USA

³Department of Physics, Duke University, Durham, NC 27710, USA

⁴Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA



Multifunctional complex oxides exhibit a variety of electromechanical properties that have the potential to enable novel functionalities in nano- and microelectromechanical systems (NEMS/MEMS). Here we present the structural and mechanical behavior of ultra-thin, single-crystalline BaTiO₃ that has been integrated on Si(100). The BaTiO₃ is epitaxially grown using oxide molecular beam epitaxy and then patterned into suspended microbridge resonators using wet-etch techniques. We find that the mismatch in thermal expansion between the Si and the epitaxial BaTiO₃ gives rise to residual strain that not only enhances the resonant frequencies of the microbridges, but also causes exceptionally large changes in resonance frequency with temperature. We also find that momentary mechanical stress applied to the microbridges using sub-nano-Newton forces can induce non-volatile changes in mechanical resonance. The non-volatile changes in resonance are analyzed within the context of quasi-stable ferroelastic domains that become dynamic under applied stress, thereby leading to changes in the Young’s modulus.