Charge transfer study of aluminum-based single electron transistors fabricated by using a controlled anodization technique

We have investigated the conduction properties of ultra small aluminum-based single electron transistors which were fabricated by using standard electron beam lithography and a controlled anodization technique. Sharply defined Coulomb-staircases due to single-electron tunneling are observed up to 30 K and the Coulomb blockade persists to temperatures as high as 80 K. Clear periodic and ideal current modulations by gate voltage are also observed up to nearly 25 K. The junction parameters were obtained by fitting the experimental conductance curves to theoretical ones. The determined total capacitance and single electron charging energy are 47 aF and 1.71 meV, respectively. The detailed analysis based on the Orthodox theory shows that asymmetric behaviors of the anodized sample are mainly due to the large anisotropy ratio in the junction resistances, not in the junction capacitances.