Multi-layered NiO/NbO/NiO fast drift-free threshold switch with high I/I ratio for selector application.

NbO 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 NbO 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 is partly due to insufficient Schottky barrier height originating from interface defects between the electrodes and NbO layer. The leakage current problem can be addressed by inserting thin NiO barrier layers. The NiO inserted NbO device is drift-free and exhibits high I/I 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 device with NiO interlayers in series with resistive random access memory (ReRAM) device demonstrates improved readout margin (>2 word lines) suitable for x-point memory array application.