3-TUNNEL-CAPACITOR MODEL FOR SINGLE-ELECTRON TUNNELING IN LAYERED THIN-FILMS

Measurements of the tunnel current as a function of applied voltage on the layered high-T(c) material TlBa2(Ca0.8Y0.2)Cu2O7 have been shown to exhibit single-electron tunneling behavior. It has been proposed that the ultrasmall capacitance required to explain the single-electron tunneling spectra obtained with a low-temperature scanning tunneling microscope arises naturally from the planar crystal structure of this high-T(c) material. This hypothesis is further examined using a single-electron tunneling model that incorporates three tunnel capacitors, a condition that is required by atomic-force-microscope studies of the topography of the film's surface. An improved fit to the tunneling conductance is obtained, providing further evidence that a key to understanding Coulomb blockade in layered materials like TlBa2(Ca0.8y0.2)Cu2O7 is the tunnel capacitors that form between multilayer CuO planes. This conclusion has important implications for the fabrication of nanoelectronic devices based on single-electron effects.