The influence of using different substrates on the structural and optical characteristics of Bi₂VO_5.5 thin films

The BVO thin films have been successfully grown on Si (100) and SiO ₂/Si (100) substrates via sol-gel technique followed by rapid thermal annealing at 650°C. The crystalline nature of the films has been studied by X-ray diffraction and indicates all the films are well-crystallized. Atomic force microscopy was used to study the surface morphology of the BVO thin films which shows the films are compact and homogeneous. The BVO film with SiO ₂ buffer layer has a larger grain size and lower root mean square roughness than that directly grown on Si. The Raman spectra measurement in the range of 300-1500 cm^-1 reveals that the buffer SiO₂ layer definitely influences the structure of BVO thin films. The optical properties of the BVO thin films are investigated using spectroscopic ellipsometric in the wavelength range of 400-900 nm. In the visible range, the refractive index of the film is about 2.42 and the extinction coefficient is 0.036.