Published online by Cambridge University Press: 15 March 2011
In this paper, molecular compounds that come from the class of tungsten or molybdenum polyoxometallates (POM) are examined as components of polymeric materials with potential use in nanolithography and molecular devices. In the past, POMs have been used as components of DUV resists with promising results, but the metallic compound presence and their unconventional processing demands discouraged their further use in microlithography. In this paper routes for the use of these compounds in e-beam nanolithography are investigated. Different resist formulations, where poly (vinyl alcohol) and poly (methyl methacrylate) are used as host polymers, will be discussed along with the related process issues.
First results from the use of polyoxometallate compounds as active elements, or components, of molecular electronic nanodevices will be also presented. The electronic transport properties of the composite materials have been tested using planar devices with contact distances of 40μm, 5μm, 50nm and 25nm. Contacts were fabricated using electron beam lithography and a lift–off process. Even at room temperature conditions conductivity peaks appear in the case of distances smaller than 25nm. These peaks are related to the energy distance of the HOMO – LUMO levels of the active molecules and the work function of the electrode used. The position and the size of the peaks depend upon the mean distance of the molecules as well as the electrode distance. On the other hand when the contact is illuminated, conductivity increases even by two orders of magnitude. This is attributed to the photon excitation of electrons from the HOMO.