Field-emission-induced electromigration method for precise tuning of electrical properties of Ni-based single-electron transistors

We have studied simple and easy technique for the fabrication of planar-type nanogap-based single-electron transistors (SETs). In this method, electromigration is induced across the nanogap by a field emission current, and then the island structure is formed in the nanogap. We call this method “activation”. Previously, we have also reported that the Ni-based SETs with multiple islands are fabricated by the activation with relatively low preset current. Furthermore, it is revealed that as the preset current I_s increases, the size of the islands is increased and the number of the islands is decreased. In this report, we investigated the electrical properties of the SET activated with relatively high preset current. When the preset current I_s was set to 3 μA, Coulomb blockade voltage observed from the activated nanogap was obviously modulated by the gate voltage quasi-periodically at 18 K, resulting in the formation of SET with a small number of islands. These results imply that the electrical properties of planar-type nanogap-based SETs are precisely controlled using the activation.