Showing papers by "Yu. A. Pashkin published in 1994"

Application of low temperature scanning electron microscopy for the investigation of single-electron tunneling circuits

Abstract: We present the first experimental results on a spatially‐resolved investigation of a SET (single‐electron tunneling) circuit using the method of low temperature scanning electron microscopy. The new technique can be operated with short electron beam pulses down to 1 μs and small beam current below 1 pA, which gives the value of the charge per pulse as low as one elementary charge. By recording the circuit voltage response to the modulated electron beam irradiation as a function of the beam coordinates on the circuit, we were able to image the potentials of different parts of the circuit. For a SET‐transistor which displayed the Coulomb blockade we found evidence of memory‐effects due to charge trapping in the vicinity of one of the junctions. Further possible applications of our method for the spatially resolved study of single‐electron circuits are suggested.

2e periodic modulation of the I-V curve of a current-biased superconducting transistor

Abstract: We have made an experimental study of the tunnelling through a current-biased superconducting single electron transistor at temperatures down to 40 mK. The current-biased transistor consisted of two ultrasmall tunnel junctions connected in series, biased through two high-Ohmic resistors (length 10 μm) located very close to the tunnel junctions. The two-probe measurement of the current-voltage characteristic has shown a periodic modulation with a gate voltage, having two separate fundamental periods in gate charge, ΔQ1=e and ΔQ2=2e, as well as higher harmonics of these two. We have found that the amplitude of the 2e-component was enhanced as superconductivity of the electrodes was suppressed with an external magnetic field. These results are discussed within the context of a parity model.