Three-Dimensional Observation of the Conductive Filament in Nanoscaled Resistive Memory Devices

Abstract

The basic unit of information in filamentary-based resistive switching memories is physically stored in a conductive filament. Therefore, the overall performance of the device is indissolubly related to the properties of such filament. In this Letter, we report for the first time on the three-dimensional (3D) observation of the shape of the conductive filament. The observation of the filament is done in a nanoscale conductive-bridging device, which is programmed under real operative conditions. To obtain the 3D-information we developed a dedicated tomography technique based on conductive atomic force microscopy. The shape and size of the conductive filament are obtained in three-dimensions with nanometric resolution. The observed filament presents a conical shape with the narrow part close to the inert-electrode. On the basis of this shape, we conclude that the dynamic filament-growth is limited by the cation transport. In addition, we demonstrate the role of the programming current, which clearly influences the physical-volume of the induced conductive filaments.

All-nanocellulose nonvolatile resistive memory

“…This is a so-called forming process that is used to initialize the resistive memory device. [32][33][34][35] After the forming process, the device showed a low-resistance state (LRS), with a resistance of 63 Ω (red line). The LRS was maintained until the negative voltage was applied.…”

“…Thus, our nanopaper memory device showed a polarity-dependent bipolar resistive-switching behavior. 32 Next, we performed retention measurements to examine the nonvolatility of the nanopaper memory device. Figure 2b shows both the LRS and HRS resistances as a function of time.…”

Bidirectional threshold switching characteristics in Ag/ZrO2/Pt electrochemical metallization cells

“…The residual Ag clusters at the bottom electrode interface can serve as the Ag source for the filament formation under negative bias applications. 26,33 However, no such transition was obtained under lower Iccs or fewer cycles, which can be attributed to the less residual Ag precipitations or clusters at the ZrO 2 /Pt interface, thus insufficient Ag source for the filament formation under negative bias. Besides, this bi-directional threshold switching can be achieved in most of the cells (more than 80%) by utilizing proper operations.…”

Coexistence of two types of metal filaments in oxide memristors

“…1-4 For ECM cells, the electron-conducting filament is composed of metal atoms coming from the active electrode (such as Cu or Ag). [5][6][7][8][9] However, the case of VCM cells is more complicated. Let us take binary transition metal oxides such as NiO As for ZnO-based VCMs, one generally considers the filament as an aggregation of oxygen vacancies.…”