A Pt/TiO₂/Ti Schottky-type selection diode for alleviating the sneak current in resistance switching memory arrays

This study examined the properties of Schottky-type diodes composed of Pt/TiO₂/Ti, where the Pt/TiO₂ and TiO₂/Ti junctions correspond to the blocking and ohmic contacts, respectively, as the selection device for a resistive switching cross-bar array. An extremely high forward-to-reverse current ratio of ∼ 10⁹ was achieved at 1V when the TiO₂ film thickness was 19nm. TiO₂ film was grown by atomic layer deposition at a substrate temperature of 250 °C. Conductive atomic force microscopy revealed that the forward current flew locally, which limits the maximum forward current density to < 10Acm^-2 for a large electrode (an area of ∼ 60 000νm²). However, the local current measurement showed a local forward current density as high as ∼ 10⁵Acm^-2. Therefore, it is expected that this type of Schottky diode effectively suppresses the sneak current without adverse interference effects in a nano-scale resistive switching cross-bar array with high block density.