The Effect of Thermal Annealing on Structural, Morphological and Optical Features of BaTiO۳ Thin Film assisted by e-beam PVD Technique

The work reported in this paper was focused on the investigation of surface morphological, microstructural, and optical features of polycrystalline BaTiO۳ thin film deposited on p-type Si < ۱۰۰ > substrate using e-beam PVD (physical vapor deposition) technique. The influence of annealing over the surface morphology of the thin film was analyzed by X-ray diffraction, atomic force microscopy and scanning electron microscopy characterization methods. When the annealing temperature was increased from as-deposited to ۸۰۰ °C there was a significant growth in the grain size from ۲۸.۴۰۷ nm to ۳۷.۸۹ nm. This granular growth of BaTiO۳ made the thin film appropriate for nanoelectronic device applications. The roughness of the annealed film got increased from ۳۱.۵ nm to ۵۲.۸ nm with the annealing temperature. The optical bandgap was computed using Kubelka-Munk (KM) method which got reduced from ۳.۹۳ eV to ۳.۸۷ eV for the as-deposited to the ۸۰۰ °C annealed film. The above reported properties made the annealed film suitable for optoelectronic applications. For polycrystalline BaTiO۳ thin film the refractive index varied from ۲.۲ to ۱.۹۸ from ۴۰۰ to ۵۰۰ nm and it was ۲.۰۵ at ۵۵۰ nm wavelength. The broad peaks in Raman spectra indicated the polycrystalline nature of the thin film. It had been also observed that with the annealing temperature the intensity of the Raman bands got increased. From these results, it was proved that annealing significantly improved the crystallinity, microstructural, surface morphological and optical features of the barium titanate thin film which made it suitable as sensors in biomedical applications as it is cost-effective, lead-free and environment friendly material.

Keywords:

Atomic Force Microscopy , Annealing , BaTiO۳ Thin film , Kubelka-Munk , Optical Bandgap , Raman spectroscopy , Scanning Electron Microscopy , Tauc-plot , UV-Visible spectroscopy