Thickness scaling and electric properties of highly (111) oriented Nb-doped Pb(Zr,Ti)O₃ thin film prepared at low temperature by a sol-gel route

A series of highly (111) oriented Pb(Nb_0.01Zr _0.2Ti_0.8)O₃ (PNZT) thin films of variant thickness were successfully achieved on Pt/Ti/SiO₂/Si substrate by a sol-gel route. By introducing Pb_0.8Ca_0.1La _0.1Ti_0.975O₃ (PLCT) layer between the PNZT film and Pt electrode, the PNZT film could be crystallized at as low as 500 °C. When a maximum applied voltage is 3 V, it was found that the PNZT film with PLCT seed layer possessed higher remnant polarization (22 μC/cm²) as film thickness was scaled down to 50 nm. It was also found that enhanced pyroelectric properties could be observed in 50-nm thickness PNZT thin film due to its relatively low dielectric constant. The results demonstrated that the film thickness could be scaled down for low voltage operations using lattice matched interface between PNZT film and PLCT seed layer on Pt/Ti/SiO ₂/Si substrate, and this interface optimization is the key technology for synthesizing thin PNZT films at low temperature with good insulating and electric properties.