Nonpolar Resistive Switching in Ag@TiO₂ Core–Shell Nanowires

Abstract

Nonpolar resistive switching (RS), a combination of bipolar and unipolar RS, is demonstrated for the first time in a single nanowire (NW) system. Exploiting Ag@TiO core-shell (CS) NWs synthesized by postgrowth shell formation, the switching mode is controlled by adjusting the current compliance effectively, tailoring the electrical polarity response. We demonstrate ON/OFF ratios of 10 and 10 for bipolar and unipolar modes, respectively. In the bipolar regime, retention times could be controlled up to 10 s, and in the unipolar mode,>10 s was recorded. We show how the unique dual-mode switching behavior is enabled by the defect-rich polycrystalline material structure of the TiO shell and the interaction between the Ag core and the Ag electrodes. These results provide a foundation for engineering nonpolar RS behaviors for memory storage and neuromorphic applications in CSNW structures.

Recent Developments and Perspectives for Memristive Devices Based on Metal Oxide Nanowires

“…Initially, a positive bias voltage of about 7 V was necessary to electrically connect the two electrodes by the formation of Cu filaments in the SiO 2 shell (electroforming process). [231] Exploiting the formation/rupture of metallic filaments across the shell layer, resistive switching was observed also in Ag-TiO 2 coreshell NWs by Manning et al [232] In this case, a nonpolar resistive switching was observed as a consequence of the formation/ rupture of Ag filaments through the TiO 2 shell layer that enabled to connect the Ag electrodes to the Ag core of the NW. The device was turned in the LRS (write) by applying a positive voltage to the Cu electrode, giving rise to the bipolar resistive switching behavior reported in Figure 13a.…”

“…Cu–core SiO 2 shell NWs dispersed in ethylcellulose have been proposed as building blocks for the realization of fully printed memristors . Exploiting the formation/rupture of metallic filaments across the shell layer, resistive switching was observed also in Ag–TiO 2 core–shell NWs by Manning et al In this case, a nonpolar resistive switching was observed as a consequence of the formation/rupture of Ag filaments through the TiO 2 shell layer that enabled to connect the Ag electrodes to the Ag core of the NW. The switching mechanism was favored by the highly defective polycrystalline microstructure of TiO 2 and by the Ag inclusions in the shell layer due to the growth process.…”

The Electro-Optical Performance of Silver Nanowire Networks

“…R jxn is a consequence of an electrically insulating few nm thick polyvinolpyrollidone (PVP) layer that forms a metal-insulator-metal configuration where ever NWs overlap to form a junction 23 . Modification of the PVP surface layer can give resistive switching memory effects 24,25 , or enhance the thermal and chemical stability of the Ag NWNs 17,26,27 .…”

Collective capacitive and memristive responses in random nanowire networks: Emergence of critical connectivity pathways

“…Ag@PVP plates). During the breakdown of a MIM junction, the growth of a conducting filament (CF) bridging the metal plates takes place and this can be regulated by distinct mechanisms [16,[19][20][21] including thermochemical, electrochemical metallization, and valence change. With the filament gradual growth, a drastic reduction in the characteristic resistance of the junction can be measured.…”