Observation of strong Coulomb blockade in resistively isolated tunnel junctions

Abstract We report measurements of the Coulomb-blockade current in resistively isolated (RIsol≫h/e2) tunnel junctions for the temperature range 60 mK mK where the charging energy Ec is much greater than the thermal energy. A zero-bias resistance R0 of up to 104RT (the tunnel resistance of the bare junction) is obtained. For eV≪Ec, the I-V curves for a given RIsol scale as a function of V/T, with I∝Vα(RIsol) over a range of V. The data agree well with numerical calculations of the tunneling rate that include environmental effects.