Properties of dielectric BaTiO3 thin films prepared by spray pyrolysis

Thin-film BaTiO3 has been prepared for the first time by spray pyrolysis. Both smooth and highly porous films were deposited depending on deposition temperature and rate. As-deposited films contained an unidentified, low-symmetry barium titanate modification. Annealing at 500-900 degrees C converted the films to the cubic phase, while annealing at 1000 degrees C produced the tetragonal phase and an increase in the grain size. As-deposited and annealed films were highly dielectric with DC resistivity in the 10(10)-10(12) Ohm . cm range. AC resistivity decreased with frequency following a power-law dependence with an exponent of -0.6 to -0.7. Both resistivity and capacitance remained stable at temperatures to 400 degrees C. The effective dielectric constant (20-25 at 10 kHz) was possibly determined by amorphous grain-boundary region with high density of traps.