Room-temperature Coulomb fingerprints in thin films of a Cu+SiO2 composite material

We study the room-temperature electrical properties of thin (similar or equal to 200 nm) SiO2 films with inclusions of Cu globules with radius similar or equal to 1 nm and separation similar or equal to 20 nm. Current-voltage curves taken across the film in different experimental arrangements show ''fingerprints'' that are fully reproducible within each setup. We observe multiple peaks with a height of similar or equal to 2 pA against the Ohm's-law background. The typical peak width is consistent with single-electron recharging of Cu globules. We interpret these data as self-selection of energetically favorable quasi-ID chains of globules, along which the current is mainly concentrated. (C) 1996 American Institute of Physics.