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

A spray pyrolysis method has been used to deposit ZnO films on polycry stalline alumina substrates. The precursor is dissolved in aqueous sol utions 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. Th ese experimental data are discussed in terms of a model which describe s the chemical nature and concentrations of the Zn precursors which ar e potential candidates for the film formation.