Resistive Switching in Pt ∕ Al2O3 ∕ TiO2 ∕ Ru Stacked Structures

The electric-pulse-induced resistive switching properties of TiO 2 , Al 2 O 3 , Al 2 O 3 /TiO 2 , and Al 2 O 3 /TiO 2 /Al 2 O 3 thin films were studied by current-voltage (I-V) measurements using Pt/insulator/Ru structures and conductive atomic force microscopy. The switching parameters of the TiO 2 film were stable, whereas those of the Al 2 O 3 films show random variations during repeated I-V measurements. Both films show resistive switching by a filamentary switching mechanism with linear conduction behavior in the low V region. The stacked film shows a bias polarity-dependent switching behavior. This suggests that the nucleation of the conducting filaments occurs at the interface where the electrons are injected.