High macroscopic piezoelectric d₃₃ of the nm-thick flexible PZT ferroelectric film

Integrated nanoelectromechanical systems (NEMS) with nm-scale piezoelectric films exhibit enormous advantages compared with traditional microelectromechanical systems. Herein, the flexible PZT ferroelectric films with 50–200 nm thickness were achieved, and their piezoelectric d₃₃ rapidly enhanced with the thickness of film increasing and the thickness of mica substrate decreasing. The d₃₃ value of the 80 nm-thick PZT film increases from 180 to 220 pC/N with the thickness of mica substrate reducing from 0.2 mm to 10 μm to largely decrease clamping strain between substrate and PZT film. Furthermore, the flexible mica substrate largely increases both the piezoelectric effect and the inverse piezoelectric effect of PZT films. These nm-scale PZT films with robust piezoelectricity will encourage the creation of new NEMS and piezoelectric devices that are flexible.