The effects of impurity-co-doping on transparent conducting Al-doped ZnO (AZO) films prepared by d.c. magnetron sputtering are described. A chemical property, namely the etching rate, of transparent conducting AZO thin films was improved by co-doping vanadium (V), without significantly altering the films' original electrical and optical properties. The resistivity of V-co-doped AZO (AZO:V) films was found to be relatively independent of V2O5 content up to 3 wt.%. Etching rates of AZO:V films in HCl and KOH solutions decreased markedly as the V2O5 content was increased above approximately 0.5 wt.%. A practical etching rate, as well as a low resistivity of 2.4 X 10(-4) Omega cm, was obtained in transparent conducting AZON films prepared with an Al2O3 content of 1 wt.% and a V2O5 content of 1 wt.% at a substrate temperature of 250 degreesC by d.c. magnetron sputtering under optimized target preparation and sputter deposition conditions. (C) 2003 Elsevier Science B.V. All rights reserved.