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, Ta, on structural,and opticalproperties of (ZnO)1-x(TiO2)x thin-films prepared by sol-gel method. Experimental results are explained and theoretical equations are suggested for optical-energy-gap, Eg, and Urbach-energy, Eu in terms of their variation with (x) and (Ta).With increased xand Ta, Eg decreases whereas Eu increases. Thebehavior of Egwas explainedby evokingthatincreasingx will randomize thecrystalperiodicity, andthat annealingtemperature(400,500, and600)⁰Crelaxes the structuremoretowardsbettercrystallineforms. The increase of Eu with increased x was attributed to the lower mass of Ti ions as compared to that of Zn ions. Generally, makingcompositesdestroysthecrystalinityobservedin pureZnO andpureTiO2films butannealingdoesimprovethe qualityof the filmintermsofitsdegreeofcrystal structure.