The electrical and optical properties of doped BTO thin films

Abstract

BaTiO3 thin films with different dopants of Fe and Co were prepared by sol-gel technique on Si and LaNiO3 coating Si substrates respectively. The x-ray diffraction patterns showed that all the films were perovskite structure and the change of lattice constant caused by dopants was undetectable. Atomic Force Microscope (AFM) was used to characterize the surface morphology of the thin films. The surfaces of films were uniform and dense except Co-doped BaTiO3 film on Si substrate. The Raman spectra showed the Fe dopant could improve the crystal quality of BTO films on these two different substrates. The results of UV reflectance for BTO thin films prepared on Si substrates showed that the reflectance peaks of Fe-doped BTO film moved to the low frequency. The Pt top electrodes were fabricated on BaTiO3/LaNiO3/Si to form a metal-ferroelectrics-metal structure and the dielectric properties of the thin films were carried out by impedance analyzer. It was found that Co dopant could increase the dielectric constant of BTO film to some extent and the Fe dopant could decrease the dielectric constant of film below 30 kHz. Both of the dopants could increase the dielectric loss of the films with the frequency increasing.