Influence of Dissipation on the Coulomb Blockade in Small Tunnel Junctions

Abstract

Effects of charging energy were studied in small-capacitance aluminum tunnel junctions in the normal state, with tunnel resistance Rt between 0.2 and 80 kΩ. Single junctions, chains and 2-dimensional arrays were fabricated. This allowed investigation of the influence of lead capacitance. For Rt > 1 kΩ the voltage offset ("Coulomb gap") determined from the I-V curve at high current is consistent with the capacitance calculated from junction area only. For single junctions with Rt near or below 10 kΩ at low current the charging effects are strongly suppressed. Results of chains with arbitrary Rt show the suppression of charging effects by dissipation. The R(T) curves are in good agreement with theory and geometrical capacitance.