Non-filamentary three-terminal resistivity switch based on interface oxidation/reduction

Abstract

We present a three-terminal resistive switching device with a 20 mol% gadolinium-doped ceria (20GDC) thin film as the solid state electrolyte. The device features a top Ta-metal gate electrode and bottom Ta-metal source and drain electrodes, separated by a 1 mm gap filled with 20GDC. Its operation relies on the redox reaction of cerium, specifically the reduction of cerium (IV) to cerium (III) at the interface between the Ta-gate and the 20GDC electrolyte. Under positive gate bias, the Ta gate electrode undergoes oxidation, while cerium is reduced, forming a conductive layer between the source and drain electrodes. Applying a negative gate bias reverses this effect. To confirm that resistivity changes originate from interface redox reactions, we conducted cyclic voltammetry at 403 K. The results demonstrate that peak current is inversely proportional to the scan rate, a characteristic of reaction at a surface. Additionally, we demonstrated that sputtering a TaO_x blocking layer beneath the gate electrode suppresses resistive switching. While the resistance changes only by a factor of two, the proposed device operates near equilibrium, is simple to fabricate, and exhibits high robustness. These characteristics make the concept of interface oxidation/reduction appealing for further exploration.