Bare Oxide Film Research Articles

Resistive switching in high-density nanodevices fabricated by block copolymer self-assembly.

Bipolar resistive switching memories based on metal oxides offer a great potential in terms of simple process integration, memory performance, and scalability. In view of ultrahigh density memory applications, a reduced device size is not the only requirement, as the distance between different devices is a key parameter. By exploiting a bottom-up fabrication approach based on block copolymer self-assembling, we obtained the parallel production of bilayer Pt/Ti top electrodes arranged in periodic arrays over the HfO2/TiN surface, building memory devices with a diameter of 28 nm and a density of 5 × 10(10) devices/cm(2). For an electrical characterization, the sharp conducting tip of an atomic force microscope was adopted for a selective addressing of the nanodevices. The presence of devices showing high conductance in the initial state was directly connected with scattered leakage current paths in the bare oxide film, while with bipolar voltage operations we obtained reversible set/reset transitions irrespective of the conductance variability in the initial state. Finally, we disclosed a scalability limit for ultrahigh density memory arrays based on continuous HfO2 thin films, in which a cross-talk between distinct nanodevices can occur during both set and reset transitions.

Synthesis and Electrochemical Characterization of Vanadium Oxide/Carbon Nanotube Composites for Supercapacitors

Capacitive properties of vanadium oxides on carbon nanotubes (CNTs) have been investigated. In structural properties, the Raman spectrum shows the characteristic peaks of V 2O 5, and XPS analysis predicts that the atomic ratio of as-prepared vanadium oxide is approximately the same as that of the stoichiometric V 2O 5. Cross-sectional scanning electron microscope images show that CNTs provide good support for uniform distribution of vanadium pentoxides. In capacitive behaviors, CNTs covered with uniformly dispersed oxides lead to a significantly improved capacitive performance, as compared with bare oxide films. Therefore, such V 2O 5/CNT nanocomposites are a potential material for power backup of hybrid electrical vehicles or portable electronics.