Chemical Nature of Electrode and the Switching Response of RF-Sputtered NbO Films.

In this study, the dominant role of the top electrode is presented for NbO-based devices to demonstrate either the resistive switching or threshold characteristics. These NbO-based devices may exhibit different characteristics depending on the selection of electrode. The use of the inert electrode (Au) initiates resistive switching characteristics in the Au/NbO/Pt device. Alternatively, threshold characteristics are induced by using reactive electrodes (W and Nb). The X-ray photoelectron spectroscopy analysis confirms the presence of oxide layers of WO and NbO at interfaces for W and Nb as top electrodes. However, no interface layer between the top electrode and active layer is detected in X-ray photoelectron spectroscopy for Au as the top electrode. Moreover, the dominant phase is NbO for Au and NbO for W and Nb. The threshold characteristics are attributed to the reduction of NbO phase to NbO due to the interfacial oxide layer formation between the reactive top electrode and NbO. Additionally, reliability tests for both resistive switching and threshold characteristics are also performed to confirm switching stabilities.