Electric field induced piezoelectric resonance in the micrometer to millimeter waveband in a thin film SrTiO3 capacitor

Thin film SrTiO3 metal–insulator–metal (MIM) capacitors were fabricated in order to characterize the piezoelectric resonance in the micrometer to millimeter waveband arising from electric field induced ferroelectricity in the SrTiO3 film. The specimens showed a second-order phase transition, and the piezoelectric resonance appeared when an electric field of 250 kV/cm was applied at room temperature. Finite element method (FEM) analysis was used to interpret the piezoelectric resonance observed in the capacitors. The FEM analysis data basically agrees well with the experimental data, and the few differences between the theoretical and experimental data are interpreted mainly as artifacts caused by overlapping of resonant/antiresonant peaks during the measurement. The piezoelectric resonance of thin film MIM capacitors is strongly influenced by the longitudinal stacked structure of the MIM.