Epitaxial Si-Integrated Defective BaTiO3 as Giant Electrostrictors at >1kHz

Defect-engineering to induce giant electrostriction has been gaining popularity in CeO2 and Bi2O3 based systems [1]. However, the enhancement is well pronounced only below 100 Hz. Here we show that 10% A-site deficient BTO, grown epitaxially on Si with TiN as a buffer layer, shows record electrostrictive strain coefficients (M31=10^-14m²/V²) even upto 5 kHz frequencies. Our samples are replete with PNRs and twin boundaries. I’ll show how Joule heating and ferroelectricity don’t play any significant role in the observed electrostrain values, and it is indeed defect-induced electrostriction that contributes to it. Our impedence spectroscopy data clearly shows that the dielectric relaxation behavior of BTO layer correlates very closely with the observed electromechanical data (in both amplitude and phase). I’ll end by suggesting guidelines to design Pb-free materials with large M at higher frequencies for MEMS based applications [2].<br/>References<br/>J. Yu, P-E. Janolin, Defining Giant Electrostriction, Journal of Applied Physics, 131, pp:170701, 2023<br/>S. Vura, S. Parathe, P. Nukala et al., Giant electromechanical response from defective non-ferroelectric epitaxial BaTiO₃ integrated on Si (100), doi: 10.21203/rs.3.rs-2661707/v1 [Pre-print]