Interface engineering for enhancement of the analog properties of W/WO <sub>3−</sub> <i> <sub>x</sub> </i> /HfO <sub>2</sub> /Pd resistance switched structures
Aleksandra Koroleva, Maxim G. Kozodaev, Yu. Yu. Lebedinskiǐ, Andrey M. Markeev
Abstract
Abstract The resistive switching behavior of W/WO 3− x /HfO 2 /Pd structures with different WO 3− x thicknesses was investigated. It was found that WO 3− x layer thickness plays a pivotal role in the switching mechanism. X-ray photoelectron spectroscopy study of the WO 3− x /HfO 2 interface revealed the oxygen vacancy formation before subsequent HfO 2 growth by atomic layer deposition. The W/WO 3− x (2 nm)/HfO 2 /Pd structure exhibited filamentary behavior with a memory window of ∼200 and a switching endurance of only 460 cycles. In contrast, increasing the WO 3− x layer thickness to 20 nm resulted in the nonfilamentary switching mode with a significant switching endurance improvement. Also, the W/WO 3− x (20 nm)/HfO 2 /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.