Structural, dielectric and ferroelectric properties of multilayer lithium tantalate thin films prepared by sol-gel technique

摘要

Multilayer lithium tantalate thin films were deposited on Pt-Si [Si( 111 )/SiO_2/TiO_2/Pt( 111)] substrates by sol-gel process. The films were annealed at different annealing temperatures (300,450 and 650 ℃) for 15 min. The films are polycrystalline at 650 ℃ and at other annealing conditions below 650 ℃ the films are in amorphous state. The films were characterized using X-ray diffraction, atomic force microscopy (AFM) and Raman spectroscopy. The AFM of images show the formation of nanograins of uniform size (50 nm) at 650 ℃. These polycrystalline films exhibit spontaneous polarization of 1.5 μC/cm~2 at an application of 100 kV/cm. The dielectric constant of multilayer film is very small (6.4 at 10 kHz) as compared to that of single crystal.