Fabrication of single-electron transistors with electromigrated Ni nanogaps

We analyze single-electron transistors (SETs) fabricated with electromigrated Ni nanogaps using the Korotkov and Nazarov (KN) model. First, we investigate nanogap-based SETs consisting of multiple Ni islands placed between the source and drain electrodes by a field-emission-induced electromigration technique known as “activation.” After the activation procedure is performed using a preset current Is of 3 μA, the drain current-drain voltage characteristics of SETs with single-island structures are obtained and analyzed by using the KN model and considering the offset charges on the islands. We determine the fitting parameters obtained by the KN model from the electrical properties of the SETs. The parameters can be explained using the geometrical structures of the SETs that are observed in both scanning electron and atomic force microscopy images after the activation procedure. This approach allows the electrical and structural properties of the single-island structures of the SETs fabricated using the activation method to be determined.