Effect of Composition and Annealing on Structural and Optical Properties of (ZnO)1-X (TiO2)X Thin Films Prepared by Sol-Gel Method

Abstract

The study describes effect of composition parameter, x, and annealing-temperature, T a , on structural, and optical properties of (ZnO) 1-x (TiO 2 ) x thin-films prepared by sol-gel method. Experimental results are explained and theoretical equations are suggested for opticalenergy-gap, E g , and Urbach-energy, E u in terms of their variation with (x) and (T a ). With increased x and Ta, E g decreases whereas E u increases. The behavior of E g was explained byevoking that increasing x will randomize the crystal periodicity, and that annealing temperature (400,500, and600)⁰C relaxes the structure more towards better crystalline forms. The increase of E u with increased x was attributed to the lower mass of Ti ions as compared to that of Zn ions. Generally, making composites destroys the crystalinity observed in pure ZnOand pure TiO 2 films but annealing does improve the quality of the film in terms of its degree of crystal structure.