Chemical spray deposition of zinc oxide nanostructured layers from zinc acetate solutions

Zinc oxide (ZnO) films were deposited by chemical spray from zinc acetate aqueous solutions using continuous and pulsed spray modes. ZnO films were characterized by scanning electron microscopy, atomic force microscopy, optical transmittance, and water contact angle (CA) measurements. ZnO films with highly structured surfaces comprising nano-needles or nanorods with root mean square roughness (Sq) up to 60 nm were grown using the continuous spray mode. Doping with In or using pulsed spary mode leads to smoother ZnO surfaces with Sq of 20 nm. The optical transmittance of the film is controlled by its surface morphology and internal scattering. Water contact angle measurements reveal that assprayed ZnO films with nanoneedle or nanorod-like crystals on the surface are hydrophilic with CA similar to 10 degrees. Structured surfaces become hydrophobic with CA similar to 134 degrees after treatment with stearic acid. (c) 2008 WILEY-VCH Verlag GmBH & Co. KGaA, Weinheim