Insulator-metal transition in Coulomb blockade nanostructures

The transition from insulating to metallic behavior is observed at low temperatures for the protected nanocluster arrays of Cu, Ag, and Au. The disappearance of the Kubo gap at low temperature in these systems, where the interparticle spacing (0.5-1 nm) is less than the nanocluster dimensions (10-15 nm), is explained to effect the transition due to strongly coupled charge fluctuations and cluster vibrations. For the same interparticle separation of Cu, Ag, and Au clusters the transition temperature is found to vary significantly, possibly due to the difference in localization arising from the lack of precise size distribution. (C) 2001 American Institute of Physics.