An investigation of vanadium concentration on the optical and electrical properties of TiO2 sol-gel derived thin films

Doped Titanium dioxide thin film with different concentrations of Vanadium (0.5, 1 and 5 % weight) , was deposited by sol-gel method on glass substrate. Structural, electrical, optical and surface roughness of thin films, were studied by XRD, EDS, LCR meter, UV-Vis spectroscopy and AFM methods, respectively. The XRD results indicated that thin film has an only anatase phase. It is observed that the crystallite sizes of the thin films decreased from 17 nm for pure TO2 to 7 nm for V doped TiO2. In addition, No phases of vanadium oxide formed because the V substituted in the titanium position in the TiO2 crystal structure. The FE-SEM cross section image of the VTO thin film shows that thin film thickness is about 536 nm. The RMS of the pure TiO2 and V doped TiO2 thin films are 3.14 and 0.78 nm, respectively. The resistivity of the thin films of pure TiO2 and doped with 0.5, 1 and 5 wt. % V were 16.7 × 107 Ω cm, 7.7 × 107 Ω cm, 1.7 × 107 Ω cm and 12.8 × 107 Ω cm, respectively. Band gap energy of the samples reduced by adding Vanadium to Titanium dioxide from 3.71 to 3.44 eV and therefore absorption edge Titanium dioxide shifted towards longer wavelengths.