Single-step sol-gel deposition and dielectric properties of 0.4 μm thick, (001) oriented Pb(Zr,Ti)O3 thin films

Single-step sol–gel deposition was attempted for realizing submicron thick, (001) oriented Pb(Zr0.53Ti0.47)O3 (PZT) thin films, using an alkoxide solution containing polyvinylpyrrolidone (PVP). A solution of molar composition, Pb(NO3)2:Zr(OC3H7n)4:Ti(OC3H7i)4:PVP:H2O:CH3COCH2COCH3:CH3OC2H4OH:C3H7nOH = 1.1:0.53:0.47:0.5:5:0.5:22:0.98, was prepared as a coating solution. Gel films were prepared on Pt(111)/TiO2/SiO2/Si(100) substrates by spin-coating, and calcined at 350 °C and annealed at 650 °C either in an electric furnace or in a near-infrared (IR) furnace. When calcined in the near-IR furnace, the films became (001) oriented on annealing. When calcined in the electric furnace, on the other hand, the films became randomly oriented on annealing. These observations indicate that the heating the gel films from the substrate side in the calcination step at 350 °C induces crystallographic orientation in the annealing step at 650 °C. The effects of the heating methods on the thermal decomposition of the gel films, and the microstructure and dielectric properties of the fired films were studied. Finally 0.4 μm thick, (001) oriented PZT films could be successfully prepared by non-repetitive, single-step deposition. The oriented film thus obtained had the remnant polarization 2Pr of 39 μC/cm2 and the dielectric constant ε′ of 960 ± 169.