Epitaxial growth of WOx nanorod array on W(001)

Nanorods of substoichiometric tungsten oxide (WOx) were grown on W(001) substrates. Two methods for the growth of nanorods were used: oxidation of the substrate under appropriate conditions and the deposition of tungsten oxide from a tungsten foil heated in the presence of oxygen. The grown nanorods were observed using a scanning electron microscope and an atomic force microscope. The diameters of the nanorods were 5-20 nm. The nanorods were slightly inclined from the directions parallel or normal to the surface. The inclination of nanorods was explained in terms of the epitaxial relationship between WO3 crystals and the W(001) substrate. The WO3 crystals formed at the initial stage of growth act as the nuclei of WOx nanorods. We observed selective enhancement of the growth in a certain epitaxial direction depending on the method of growth, and an array of WOx nanorods was produced on the W(001) substrate., (C) 2004 Elsevier Ltd. All rights reserved.