Effect of aging on microstructural and optical properties of sol-gel dip coated BaTiO3 thin films

This paper reports the effect of aging, thickness, and annealing temperature on microstructural and optical properties of sol-gel dip-coated BaTiO3 (BTO) thin films. The absence of any sharp peaks in the XRD pattern confirmed the amorphous nature of thin films regardless of the aging time of the solution and the thickness. Annealed BTO thin films showed the polycrystalline structure of films, which indicated the formation of a single-phase compound, and increased the intensity with respect to the annealing temperature from 550 to 650 °C. The crystallite size of annealed films increased from 19.44 nm to 23.6 nm, while the lattice strain and dislocation density decreased from 6.63 × 10−3 to 5.65 × 10−3 and 2.65 × 1011 to 1.79 × 1011 cm−2 as the annealing temperature increased from 550 to 650 °C, respectively. The bandgap of as-deposited (solution aged from 48 - 96 h) films decreased from 3.90 to 3.87 eV, while the bandgap of annealed films increased from 3.19 to 3.86 eV as the annealing temperature increased from 550 to 650 °C owing to releasing the defects of films. The near band edge emission (NBE) of all annealed samples was observed to be 361 nm which is in close agreement with the estimated bandgap. The variation of aging, thickness, and annealing temperature of BTO thin films can significantly improve the physical properties of optoelectronic applications.