Tunneling and negative resistance effects for composite materials containing polyoxometalate molecules

In this paper, molecular compounds that come from the class of tungsten or molybdenum polyoxometalates (POMs) are examined as components of polymeric materials with potential use in molecular devices. The idea is to combine POMs with resist systems in order to obtain materials suitable for fabrication of molecular electronic devices. Several resist components have been tested and the transport properties have been investigated. Planar and vertical devices have been prepared in order to investigate the transport properties of these materials. Measurements with planar A] or Au electrodes have shown that these materials present conductivity peaks at room temperature conditions. In some cases, the photocurrent has proved to be significant. The use of vertical capacitor structures allowed the investigation of the dependence of the dielectric constant of the composite material upon POM concentration as well as dielectric breakdown. In the case of thinner films (less than or equal to 10 nm) negative resistance effects at room temperature conditions are observed. (C) 2004 Elsevier B.V. All rights reserved.