Review of morphological, optical and structural characteristics of TiO2 thin film prepared by sol gel spin-coating technique

Abstract

Optical, structural and morphological properties of titanium dioxide (TiO₂) deposited by spin coating method have been reviewed in the current work. Sol–gel spin coating is a cost effective and versatile technique due to intellectual properties like simple instruments, easy preparation technique, and less time consuming. In this method, compound in the form of metal oxides is liquefied in a specific liquid in order to bring it back as a solid in a skillful manner. Study of metal oxide thin films have valuable applications in numerous semiconductor devices such as optoelectronics devices and solar energy converters etc. X-ray diffraction (XRD) analysis has been used for studying TiO₂ thin films and scanning electron microscopy (SEM) analysis has been applied for morphological investigation and to prove the nanosized structure. Optical and structural properties have been studied as a function of the annealing temperatures. XRD analysis reveals that the films crystallize in orthorhombic brookite phase. Moreover, UV-visible has been used to investigate the optical properties of material. XRD characterization indicates that crystalline structure of TiO₂ thin films improves with increasing annealing temperatures which confirms the anatase form of TiO₂ thin film. Optical band gap is significantly dependent on the annealing temperatures. The refractive index may increases with increase of crystallite size. The TiO₂ film annealed at 400 °C shows high refractive index 2.52 at a wavelength of 335 nm. Moreover, optical band gapes of thin film vary approximately from 3.3 to 3.46 eV which show strong relation with annealing temperature.