Low power Ti-doped NbO2-based selector device with high selectivity and low OFF current

The crossbar array-based resistive memory is considered a potential architecture for high-density nonvolatile memory applications. However, the sneak current path problem associated with the crossbar array structure limits its use in practical applications. This limitation can be removed by employing a selector device in the crossbar array structure. Therefore, we propose NbO2 as a selector device as it operates at a rapid speed during the insulator-metal transition (IMT). Herein, we fabricated a Ti-doped NbO2 selector device and demonstrated a very low OFF current (5 x 10-11 A). The effect of Ti doping in the NbO2 device was studied by varying the Ti concentration during a radio frequency co-sputtering process. We intentionally prevented the formation of Nb2O5, and a high-quality NbO2 layer was deposited with an appropriate Ti concentration. Furthermore, we modulated the IMT characteristics of the NbO2 device by varying the Ti concentration. The fabricated Ti-doped NbO2 selector device showed an ION/IOFF ratio greater than 5 x 104. Additionally, a drift-free fast switching operation (< 20 ns) was achieved for the optimized selector device. These results suggest the high suitability of IMT-based NbO2 devices in selector applications. (c) 2021 Elsevier B.V. All rights reserved.