Threshold Switching Characteristics of Nb/NbO2/TiN Vertical Devices

Abstract

We have observed threshold switching (TS) with minimal hysteresis and a small threshold electric field (60–90 kV/cm) in Nb/NbO2/TiN structures. The TS was unipolar with certain repeatability. A less sharp but still sizable change in the device resistance can be observed up to 150 ◦C. The TS without Nb capping layer exhibited hysteretic characteristics. It was proposed that the surface Nb2O5 layer on NbO2 could significantly modify the TS in this vertical device. This understanding of the surface effect will allow further control of the non-linear IV characteristics for NbO2-based switches or selector devices.