Effect of zinc nitrate concentration on structural and optical properties of ZnO thin films deposited by Spray Plasma device

• Spray Plasma technique was used to deposit ZnO films on glass substrate at 200 °C.
• Effect of Zn(NO3)2 concentration on the structural and optical properties were investigated.
• Grain size increases as the concentration increases from 0.1 to 0.4 M.
• Better crystalline quality is obtained at 0.2 M.
• Transmittance decreases in the visible range when the concentration increases.

ZnO thin films were deposited on glass substrate at 200 °C by Spray Plasma device using an aqueous solution of zinc nitrate. In this technique, the energy required for chemical transformations of precursors to zinc oxide is provided by plasma electrons rather than heat transfer. The effect of solution concentration on the structural and optical properties of the deposited films was investigated. X-ray diffraction results show that nanostructured polycrystalline films are formed with the typical wurtzite structure. The c-axis orientation growth depends highly on the initial concentration of precursor. Williamson–Hall calculations, atomic force and transmission electron microscopy images show an increase of grain size with an increase in molar concentration from 0.1 to 0.4 M. The transmittance decreases from 85 to 50% with an increase of the molar concentration.