As an alternative to transistor-based flash memories, redox reactions mediated resistive switches are considered as the most promising next-generation nonvolatile memories that combine the advantages of a simple metal/solid electrolyte (insulator)/metal structure, high scalability, low power consumption, and fast processing. For cation-based memories, the unavailability of in-built mobile cations in many solid electrolytes/insulators (e.g., TaO, SiO, etc.) instigates the essential role of absorbed water in films to keep electroneutrality for redox reactions at counter electrodes. Herein, we demonstrate electrochemical characteristics (oxidation/reduction reactions) of active electrodes (Ag and Cu) at the electrode/electrolyte interface and their subsequent ions transportation in FeO film by means of cyclic voltammetry measurements. By posing positive potentials on Ag/Cu active electrodes, Ag preferentially oxidized to Ag, while Cu prefers to oxidize into Cu first, followed by Cu/Cu oxidation. By sweeping the reverse potential, the oxidized ions can be subsequently reduced at the counter electrode. The results presented here provide a detailed understanding of the resistive switching phenomenon in FeO-based memory cells. The results were further discussed on the basis of electrochemically assisted cations diffusions in the presence of absorbed surface water molecules in the film.

A single and mixed-phases SnO2 (M-SnO2) nanostructures were synthesized by a simple spray pyrolysis method. The nanostructural crystallinity, surface morphology and optical evolution of Ba-doped tetragonal phase SnO2 with different Ba contents were studied by x-ray diffraction, atomic force microscopy, ultraviolet-visible spectroscopy and photoluminescence spectral measurements. The M-SnO2 with orthorhombic as well as tetragonal phases are formed in 6% Ba-doped SnO2 sample and it exhibits the highest average transmittance 86% with blue-shift of the optical band gap. The observed strong red emission at ∼ 615 nm might be encouraging for the implementation of red emission based on Ba-doped transparent conducting electrodes.

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