Multi-layered NiO_y/NbO_x/NiO_y fast drift-free threshold switch with high I_on/I_off ratio for selector application

NbO₂ has the potential for a variety of electronic applications due to its electrically induced insulator-to-metal transition (IMT) characteristic. In this study, we find that the IMT behavior of NbO₂ follows the field-induced nucleation by investigating the delay time dependency at various voltages and temperatures. Based on the investigation, we reveal that the origin of leakage current in NbO_x is partly due to insufficient Schottky barrier height originating from interface defects between the electrodes and NbO_x layer. The leakage current problem can be addressed by inserting thin NiO_y barrier layers. The NiO_y inserted NbO_x device is drift-free and exhibits high I_on/I_off ratio (>5400), fast switching speed (<2 ns), and high operating temperature (>453 K) characteristics which are highly suitable to selector application for x-point memory arrays. We show that NbO_x device with NiO_x interlayers in series with resistive random access memory (ReRAM) device demonstrates improved readout margin (>2⁹ word lines) suitable for x-point memory array application.