Surface, phase transition and impedance studies of Zr- mutated BaTiO3 lead-free thin films

Lead (Pb) based electronic materials are facing global restriction due to the toxicity of lead. Presently, there is a need for designing and studying Pb-free thin films. In the present work, we fabricated lead-free Zr-substituted BaZr0.1Ti0.9O3 (BZT10) and BaZr0.2Ti0.8O3 (BZT20) thin films on Pt/TiO2/SiO2/Si substrates by sol-gel method using spin coating technique. The major drawback of BZT solid solutions is high processing temperature (1400 degrees C-1500 degrees C). For fabrication of micro-system devices compatible with the current complementary metal oxide semiconductor (CMOS) technology, the primary requirement is fabrication of BZT thin films at lower processing temperature. So, we have developed BZT thin films at low annealing temperature 750 degrees C. The prepared thin films were characterized by grazing incidence X-ray diffraction (GIXRD) and Raman spectroscopy for structural study. The phase variation from tetragonal to cubic with Zr concentration has been noticed in the structural analysis and is consistent with temperature dependent dielectric study. Surface studies of thin film are related to the functionality of thin film in various technical applications. The average grain size and root mean square (RMS) roughness were calculated from Atomic Force Microscope (AFM) images. Local elastic properties have been analyzed by force modulation mode of AFM. The ferroelectric properties of BZT thin films decrease on increasing Zr content to 20 mol%. Impedance spectroscopy analysis at different bias voltages has been carried out for these lead-free BZT thin films. The high value of dielectric constant and impedance makes BZT worthy material for many technical applications.