Resistive switching and metallic-filament formation in Ag(2)S nanowire transistors.

Memory resistors (memristors), as a fourth fundamental integrated circuit unit, have great potential application in nonvolatile random-access memory (RAM) and synaptic circuits. Recently, HP labs have presented a memristor in nanoscale systems in which solid-state electronic and ionic transport are coupled under an external bias voltage. Resistance switches related to the formation and elimination of conductive pathways are the key components for building a memristor. Since the resistance switching in Ag2S was first observed in 1976, many advances have been achieved in the fieldofelectrically inducedresistive switchingeffects, andmany findings were neatly summarized in a recent review article. For example, the switching phenomenon has been recently observed in Pt/TiO2 nanosystems, [2,3] Ag2S/Ag nanowire heterostructures, phase-change Ag2Se and GeTe nanowires, nanoscale amorphous Si structures, and graphene-based atomic-scale switches. For these twoterminal devices, atomic migration inside the nanostructures connecting the two electrodes is critical to their switching properties. A typical example is afforded by intensive investigations of Ag2S. Ag2S is an important solid-state electrolyte material with both electronic and ionic conduction at room temperature. Therefore, Ag2S nanowires are thought of as the fundamental building blocks for nanoscale switching devices. However,much effort is still needed in the research ofAg2S nanowire switches for several reasons. Firstly, the synthesis of high-quality single-crystalline Ag2S nanowires is still very difficult. Secondly, only a fewworks have reported on the