Dependence of precursor composition on patterning and morphology of sol–gel soft lithography based zinc zirconium oxide thin films

Abstract

Array-like surface patterned zinc zirconium oxide thin films (135–163nm thickness) on soda lime silica glass substrate were prepared by sol–gel soft lithography from the precursor solutions (8wt% equivalent metal oxides) having zinc acetate dihydrate (ZA) and zirconium oxychloride octahydrate (ZOO=0–100mol% w.r.t. ZA) in ethanol-2-butanol medium with acetylacetone. The ZOO concentration in solutions strongly influenced the pattern formation, crystallinity, morphology and optical property of the films. The films were crystalline in nature and enriched with only h-ZnO or a mixture of h-ZnO and c-ZrO2 below 55mol% of ZOO content. On increasing ZOO concentration, a systematic change in morphology of h-ZnO nano/micro crystals from spherical to rod-shaped to sunflower-like particles was evident from electron microscopes (FESEM and TEM). Below 30 and above 65mol% of ZOO, light surface patterns formed. However, the films from 30 to 65mol% ZOO containing solutions evident distinct surface patterns with average periodicity, 1.5μm and peak height, 20–70nm by AFM measurements. The films were also characterized by UV–vis and FTIR spectral studies. Water and chloride contents from ZOO in the precursor solutions found to play a key role for generation of the film characteristics.