Threshold Switching Characteristics of Nb/NbO2/TiN Vertical Devices

We have observed threshold switching (TS) with minimal hysteresis and a small threshold electric field (60-90 kV/cm) in Nb/NbO
₂
/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 Nb
₂
O
₅
layer on NbO
₂
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 NbO
₂
-based switches or selector devices.