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

摘要

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 proper-ties were studied. The X-ray diffraction (XRD) study reveals that, the film becomes crystallized when the annealing temperature is above 550 degrees C. In addition, all the films show tetragonal BaTiO3 crystal structure without any second phase or reaction phase formation after annealed at 750 degrees 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 degrees 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.