Annealing Temperature-Dependent Structural, Optical, and Electrical Properties of [(Ba1-zCaz)(Zr0.1Ti0.9)O3], (z=0.155), Films

Thin films were deposited, on quartz and p-Si (100) substrates, by radio frequency (RF) sputtering of ceramic barium calcium zirconate titanate [(Ba1-zCaz)(Zr0.1Ti0.9)O-3], (z = 0.155), target. The as-deposited films were annealed for one hour at different temperatures, between 500 degrees C and 800 degrees C. The occurrence of film crystallization was observed on annealing at and above 600 degrees C. However, films peeled out on annealing at 800 degrees C. The structure, optical transmittance, dielectric constant and leakage current of the prepared films (hereafter referred to as BCZT(0.9) films), annealed at different temperatures, were measured. Refractive index and optical bandgap were obtained from the measured optical transmittance of the films deposited on quartz substrates and annealed at different temperatures. The optical bandgap of the BCZT(0.9) films was found to reduce from 4.24 to 3.87 eV with the increase in annealing temperature. On crystallization, the leakage current density of the prepared films decreased by order of 3, from similar to 10(-6) for amorphous to similar to 10(-9) A cm(-2) for crystalline films. The current-voltage variations of the prepared films exhibit different conductions for different annealing treatments. The dielectric constant was obtained maximum, 148 (at 1 MHz), and leakage current density minimum, 3.6 x 10(-9) A cm(-2) (at 3.0 x 10(2) kV cm(-1) electric field), for the films annealed at 750 degrees C. Electrical properties were observed to improve for the films annealed at 750 degrees C than other annealed films.