Thin solid films consisting of ZrO2 and Ta2O5 were grown by atomic layer deposition at 300 °C. Ta2O5 films doped with ZrO2, TaZr2.75O8 ternary phase, or ZrO2 doped with Ta2O5 were grown to thickness and composition depending on the number and ratio of alternating ZrO2 and Ta2O5 deposition cycles. All the films grown exhibited resistive switching characteristics between TiN and Pt electrodes, expressed by repetitive current-voltage loops. The most reliable windows between high and low resistive states were observed in Ta2O5 films mixed with relatively low amounts of ZrO2, providing Zr to Ta cation ratio of 0.2.
Thin solid films consisting of ZrO 2 and Fe 2 O 3 were grown by atomic layer deposition (ALD) at 400 °C. Metastable phases of ZrO 2 were stabilized by Fe 2 O 3 doping. The number of alternating ZrO 2 and Fe 2 O 3 deposition cycles were varied in order to achieve films with different cation ratios. The influence of annealing on the composition and structure of the thin films was investigated. Additionally, the influence of composition and structure on electrical and magnetic properties was studied. Several samples exhibited a measurable saturation magnetization and most of the samples exhibited a charge polarization. Both phenomena were observed in the sample with a Zr/Fe atomic ratio of 2.0.
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A comparative study of MIM-RRAM structures with different insulator materials is presented. Admittance memory mapping was carried out at 0 V dc bias, revealing two clearly separated states, both in terms of conductance and susceptance. The memory in the ON state can be modeled by means of a two parameter (resistance and inductance) equivalent circuit. The parameter extraction provides memory maps for the resistance and the inductance as well. The transition shapes between the ON an OFF state are different for each structure due to specific physical mechanisms.
Introduction Nanostructured Co3O4 in thin film form may possess and demonstrate a variety of properties making the material attractive for several applications. Co3O4 has been investigated as an important electrode material [1-4], gas sensor [5, 6], catalyst [7, 8], or superhydrophobic coating [9]. Co3O4 films have demonstrated resistive switching properties potentially enabling their application in resistive random access memory devices [10, 11]. Cobalt oxide, Co3O4, containing Co 2+ and Co 3+ ions, is recognized as magnetic semiconductor material [12]. Antiferromagnetic behavior with characteristic magnetization-field curves can be demonstrated by Co3O4 nanoparticles [13]. Regarding the possible applications in spintronics, it may occur necessary to activate ferromagnetic coupling in Co3O4 nanoparticles by hybridization with foreign materials, e.g. graphene oxide [14]. Co3O4 films have been grown by oxidation of electron-beam evaporated Co layers [15], pulsed laser deposition [5, 10] chemical bath deposition [1, 6], chemical solution deposition [8, 11], hydrothermal method [2, 13], solvothermal synthesis [9], spray pyrolysis [16]
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