Nanoporous WO3 from anodized RF sputtered tungsten thin films

We report the first electrochemical anodization of RF (radio-frequency) sputtered tungsten (W) thin films. High pressure sputtering was utilized to produce W films of low intrinsic stress with a high degree of adhesion to the transparent substrates. Structurally and uniformly porous tungsten trioxide (WO3) films were obtained under optimised anodization conditions in fluoride ion-containing electrolyte. Crystalline WO3 was obtained after annealing the films at 450 degrees C. SEM and XRD characterisation techniques were used to determine the surface morphology and crystal structure of the non-anodized and anodized films. (C) 2009 Elsevier B.V. All rights reserved.