Effect of grain size of Pb(Zr_0.4Ti_0.6)O₃ sol-gel derived thin films on the ferroelectric properties

Lead zirconate titanate (PZT) (Zr/Ti = 40/60) thin films on Pt/SiO₂/Si substrate with greatly different grain size were attained well with controlled atomic composition and crystalline orientation by varying the starting solution composition and annealing time. Small and large grained films with (1 1 1)-preferred orientation were obtained and their grain sizes were approximately 110 and 370 nm, respectively. Since annealing treatment induced the alternation of microstructure and stress at the interface, the effect of grain size was discussed in a standpoint of microstructural characteristic. Measurements of ferroelectric and electric properties revealed that small grained film presents more gradual polarization behavior, less degradation of polarization through switching cycles, and lower leakage current density than large grained film.