Effects of post annealing on the material characteristics and electrical properties of La doped BaTiO3 sputtered films

La-doped BaTiO3 thin films with 200 nm thickness were fabricated by r.f. magnetron sputtering system onto Pt/Ti/SiO2/Si substrates. The effects of post-annealing and the amount of dopant on microstructure and electrical properties were studied. The X-ray diffraction (XRD) study reveals that, the film becomes crystallized when the annealing temperature is above 550 °C. In addition, all the films show tetragonal BaTiO3 crystal structure without any second phase or reaction phase formation after annealed at 750 °C. The X-ray photoelectron spectroscopy (XPS) results provide the evidence to support the existence of La2O3 with excess of BaTiO3 structure, when the dopant content reaches more than 1.4 at.%. The dielectric constant also increases with increasing annealing temperature and it may be due to the better crystallinity and larger grain sizes. The 0.1 La film annealed at 750 °C shows a high dielectric constant of 487 measured at 1 MHz. The doped film in the as-deposited condition yields a reduction of leakage current was also observed.