EFFECT OF PH OF THE SOLUTION ON THE DEPOSITION OF ZINC-OXIDE FILMS BY SPRAY-PYROLYSIS

A spray pyrolysis method has been used to deposit ZnO films on polycrystalline alumina substrates. The precursor is dissolved in aqueous solutions with different pH values. Depending on the pH, the growth rate either is low (less than 0.2 mum.h-1) for pH less-than-or-equal-to 3.1 and pH greater-than-or-equal-to 4.7 or has significant values (> 1.5 mum.h-1)for 3.5 less-than-or-equal-to pH less-than-or-equal-to 4.3. These experimental data are discussed in terms of a model which describes the chemical nature and concentrations of the Zn precursors which are potential candidates for the film formation.