Structure and electrical properties of tungsten oxide nanorods epitaxially organized on a mica substrate

Our objective was to fabricate nanosized tungsten oxide rods and to test their sensing properties. In the present report, we focus on the crystallographical structure and the electrical properties of tungsten nanorods. The tungsten oxide nanorods were grown by vapor transport from a WO₃ layer onto a substrate (Mica). The nanorods growth was controlled by the temperature gradient between the WO₃ layer and the substrate. Their morphology was investigated by AFM and their structure by TED and TEM. We have investigated the conductivity of the WO₃ nanorods with a technique derived from atomic force microscopy operating in contact mode with a conductive tip (C-AFM). Its provides at the same time a classical topographic image of the sample surface and an image representative of the local electrical resistance between the tip and a metallic contact on the substrate. We also investigated the electrical properties of the WO₃ nanorods by the current-voltage responses in a bias range of 0 ± 1 V. We have performed experiments in an environmental chamber and characterized the role of water vapor on the electrical conductivity of WO₃ nanorods.