Zinc oxide holds considerable promise as an optical
transparent conducting material due to its wide band
gap (~ 3.3eV), its amenability to defect or impurity
doping, and other desirable properties such as low cost
and non-toxicity [1]. Thin films of transparent conducting
zinc oxide have been prepared by a wide variety
of techniques, including reactive evaporation [2, 3],
r.f. sputtering, d.c. and ion beam sputtering [4-10],
chemical vapour deposition [ 11-14] and spray pyrolysis
[15-20]