Piezoelectric properties of bilayer ferroelectric thin films based on (1−x)[Ba(Zr0.2Ti0.8)O3] –x(Ba0.7Ca0.3TiO3)

Abstract

We demonstrate that a bilayer heterostructure, comprised of a tetragonal (T) 0.7[Ba(Zr0.2Ti0.8)O3]−0.3(Ba0.7Ca0.3TiO3) (0.7BZT-0.3BCT) film deposited on a rhombohedral (R) 0.3[Ba(Zr0.2Ti0.8)O3]−0.7(Ba0.7Ca0.3TiO3) (0.3BZT-0.7BCT)film, on Pt/Ti/SiO2/Si substrates leads to a significant enhancement in piezoelectric properties. The observed enhancement in the piezoelectric properties could be attributed to that ferroelectric domains are tethered only by a soft R under layer, and not by the hard substrate. The piezoelectric constant is approximately 120pm/V for the bilayer thin films, which is two orders of magnitude larger than what is observed in constrained single-layered 0.7BZT-0.3BCT thin films. Such tailoring of piezoelectric behaviors is very attractive for a variety of electromechanical devices.