Elaboration and characterization of sol-gel derived ZrO2 thin films treated with hot water

► Preparation of ZrO2 thin films via sol-gel route by spin-coating method. ► Film thickness and refractive index varied as a function of molar ratio of EtOH during sol preparation and annealing temperature applied. ► Tetragonal ZrO2 formed after annealing at 400 °C. ► Crystallinity of ZrO2 was enhanced by increasing molar ratio of EtOH. ► A hot-water treatment reduced film thickness and improved crystallinity of sol-gel derived oxide.