Resistive switching characteristics of a modified active electrode and Ti buffer layer in Cu[sbnd]Se-based atomic switch

Abstract

Atomic switches are well-known promising candidates for future application in non-volatile logic memory devices. The resistive switching characteristics of these devices depend on the formation of a conductive filament (CF) by active metal electrodes. However, the formation of a stable CF is still a challenge owing to filament overgrowth in the solid electrolyte. To achieve controlled CF growth, we have used a modified active electrode with different CuxSe1−x composition ratios (0.01 < x < 0.45) and a titanium (Ti) buffer layer. The optimum composition was determined to be Cu0.11Se0.89/Ti (2.5 nm) for which excellent resistive switching properties were observed, such as a high on/off ratio of 104, low operating voltage, uniform resistance distribution, ten-year data retention at 85 °C, and uniform endurance (2000 cycles). The improvement is can be described from the high controllability of the oxidation-reduction reaction rate of the optimized CuSe modified active electrode by the means of Ti buffer layer and the TiO bond formation at the Ti/Al2O3 interface. In addition, depth profiles of the conductive filament based on Cu0.11Se0.89 with a Ti buffer layer were studied by performing current atomic force microscopy (I-AFM) to evaluate the enhancements in electrical performance and reliability resulting from the insertion of the Ti buffer layer.