Tunable Negative Differential Resistance and Resistive Switching Properties of Amorphous WOₓ Devices

The development of multifunctional electric device is of great significance for improving the integration dense of integrated circuits in the future. Herein, amorphous WO _x -based memristor was fabricated and the mechanism of resistance switching was studied in detail. The device exhibited a stable coexistence of bipolar resistive switching (RS) and negative differential resistance (NDR) behaviors at room temperature, which could modulated by changing the annealing time at 300 °C. The optimal high-resistance state (HRS)/low-resistance state (LRS) resistance ratio of ~30 was obtained by postannealing in 100 min. However, both RS and NDR behaviors disappeared with the crystallization of amorphous films when the annealing time was 300 min. The Ohmic conduction mechanism should be responsible for the charge transport of LRS, while the HRS transmission was corporately dominated by the trap-controlled space charge limited conduction (SCLC) and Poole-Frenkel (P-F) emission. The change of trap levels modulated by postannealing was calculated and considered to be the reason for the change of RS and NDR behaviors. Raman spectroscopy provided evidence for the formation of strong W-O bonds, which contributed to the disappearance of RS and NDR behaviors.