Wide-range control of tunnel resistance on metallic nanogaps using migration

A simple technique, based on electromigration induced by field emission current, is developed in order to control a tunnel resistance on nanogap electrodes. In this paper, we study a controllability of the resistance on nanogap electrodes by only adjusting the applied current. First, initial planar nanogaps of Ni with below 50 nm separation were defined on SiO₂/Si substrate. Then, the voltage was applied to the nanogaps while monitoring the current passing through the gaps at room temperature. The applied voltage was slowly ramped up until the current reached a preset value. With increasing the preset value from about 1 nA to 30 μA, the resistance of the nanogaps decreased ranging from the order of 100 TΩ to 10 MΩ. These results suggest that this technique can contribute to simplifying a fabrication process of tunneling devices.