Principle of a variable capacitor based on Coulomb blockade of nanometric-size clusters

We show how Coulomb blockade of electrons in a dispersive set of clusters embedded in the dielectric of a capacitor can be used to design a voltage tunable variable capacitor (varactor). We calculate the variation of capacitance for typical size distribution of the clusters and as a function of the dielectric constants of the insulators. We also discuss the temperature and frequency dependence of the capacitor.