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

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