PREPARATION OF ZNO FILMS BY SPRAY-PYROLYSIS

Decomposition of zinc acetylacetonate monohydrate (Zn(acac)(2) . H2O) to produce undoped ZnO films by spray pyrolysis has been investigated between 100 and 400 degrees C. Spray trials were conducted in both dry conditions and with excess water. Films with enhanced adhesion, optic al transmission and conductivity were deposited above 200 degrees C. W ith excess water this temperature correlated with a change in reaction mechanism from intermolecular and intramolecular at T < 200 degrees C to pyrolytic and hydrolytic/pyrolytic at T > 200 degrees C, Water enh anced the reactant utilisation and yielded films with lower resistivit y. Use of lamps to heat the spray served only to decrease surface roug hness. XRD assessment of preferred orientation and grain size is also presented. Annealing in a reducing atmosphere reduced the resistivity of the films by three orders of magnitude, the lowest obtained being s imilar to 10(-4) Ohm . m.