Interface Engineering For Enhancement Of The Analog Properties Of W/Wo3- (X) /Hfo2/Pd Resistance Switched Structures

The resistive switching behavior of W/WO3-x /HfO2/Pd structures with different WO3-x thicknesses was investigated. It was found that WO3-x layer thickness plays a pivotal role in the switching mechanism. X-ray photoelectron spectroscopy study of the WO3-x /HfO2 interface revealed the oxygen vacancy formation before subsequent HfO2 growth by atomic layer deposition. The W/WO3-x (2 nm)/HfO2/Pd structure exhibited filamentary behavior with a memory window of similar to 200 and a switching endurance of only 460 cycles. In contrast, increasing the WO3-x layer thickness to 20 nm resulted in the nonfilamentary switching mode with a significant switching endurance improvement. Also, the W/WO3-x (20 nm)/HfO2/Pd structure demonstrated synaptic behavior both in DC and pulse regimes. The gradual increase and decrease of conductance with the application of consecutive pulses demonstrated the capability to emulate synaptic long-term potentiation and depression behavior.