This paper reports the characterization of lithium
tantalite (LiTaO3) thin films deposited by sol gel process. Thin films
were deposited on (001) sapphire substrates by spin coating. In order to
study the effect of annealing temperature on the structural and optical
properties, the films were annealed at several heating temperatures, ranging
from 600 to 750 °C. From X-ray diffraction measurements it is confirmed
that LiTaO3 films are highly c-axis oriented, the line width and the
intensity of the (006) peak are sensitive to the variation of the annealing
temperature and the best results were found at 700 °C. From SEM pictures
it is found that the grain size increases from 100 to 200 nm when the
annealing temperature is increased to 700 °C. From the optical
transmittance and absorbance measurements, the band gap energy was
extrapolated at about 4.6 eV which closely agrees with the LiTaO3 bulk
value. Fourier transform infrared (FTIR) reflectivity and Raman
backscattering were used as two complementary experiments to probe the zone
center optical phonons in the lithium tantalite thin films.