  In this study, we have delineated the preparation and influence of Fe doping
on microstructural and optical properties of the pristine and Fe incorporated
TiO$_2$ thin film with different Fe concentrations (0, 2, 4, 6, and 8 at.% ).
The samples are prepared by easier and cost-saving way of spray pyrolysis
technique (SPT) using Ti(OCH$_2$CH$_2$CH$_2$CH$_3$)$_4$ as a precursor of
mother material. The effect of Fe in the microstructure and phase formation of
TiO$_2$ thin films is investigated by XRD analysis. XRD investigation depicts
that the pristine product corresponds to anatase phase of TiO$_2$ and remains
uncontaminated with addition of 2 at.% Fe impurity. It is also observed that Fe
introduces a phase transition from anatase to rutile after adulterating more Fe
contents (4, 6 and 8 at.%). In order to study optical characteristics, UVvis
spectroscopy has been employed which revels that UV absorption for the Fe
incorporated TiO$_2$ products are noticed to move to a longer wavelength (red
shift) and Fe contents lessen bandgap energy from 3.81eV (0 at.% Fe) to 3.70 eV
(8 at.% Fe) of the TiO$_2$ thin films. The impact of Fe on the optical
constants such as refractive index, complex dielectric constants, $\tan\delta$,
VELF and SELF, dispersion parameters of obtained titanium dioxide samples has
been studied. The results display that Fe influences the structural and optical
characteristics significantly.
