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Tuning the memristive response of TaO$_x$-based devices with Ag Nanoparticles

R. Leal Martir, A. J. T. van der Ree, M. H. Aguirre, G. Palasantzas, D. Rubi, M. J. Sánchez

Abstract

Defect engineering is a key strategy to control resistive switching (RS) in oxide-based memristive devices, where oxygen vacancy (OV) dynamics governs filament formation and rupture. We investigate the effect of Ag nanoparticles (AgNPs) embedded in the top electrode of Pt/Ta2O5/TaO2/Pt memristors and analyze their RS behavior and statistical stability. Devices without AgNPs exhibit two hysteresis switching loops (HSLs) with opposite chiralities, originating from the participation of the Pt/Ta2O5 top interface and the Ta2O5/TaO2 bottom interface. Incorporating AgNPs reduces the overall device resistance and selectively suppresses one loop, yielding a single, well-defined switching mode. Moreover, devices incorporating Ag-NPs show markedly reduced cycle-to-cycle variability of the high-resistance state, as confirmed by Weibull analysis, indicating improved endurance and switching reproducibility. Within a filamentary RS framework, we attribute this behavior to local metallization of the top interface by AgNPs, which partially inhibit OV transport and confines the RS dynamics to the bottom interface. Numerical simulations with the Oxygen Vacancy Resistive Network (OVRN) model succesfully reproduce the experimental HSLs, statistical trends, and tunable ON/OFF ratios with AgNPs coverage. These findings demonstrate that targeted interface metallization via metallic nanoparticles provides an effective route to control multi-interface RS dynamics and improve switching stability in without modifying the oxide architecture.

Tuning the memristive response of TaO$_x$-based devices with Ag Nanoparticles

Abstract

Defect engineering is a key strategy to control resistive switching (RS) in oxide-based memristive devices, where oxygen vacancy (OV) dynamics governs filament formation and rupture. We investigate the effect of Ag nanoparticles (AgNPs) embedded in the top electrode of Pt/Ta2O5/TaO2/Pt memristors and analyze their RS behavior and statistical stability. Devices without AgNPs exhibit two hysteresis switching loops (HSLs) with opposite chiralities, originating from the participation of the Pt/Ta2O5 top interface and the Ta2O5/TaO2 bottom interface. Incorporating AgNPs reduces the overall device resistance and selectively suppresses one loop, yielding a single, well-defined switching mode. Moreover, devices incorporating Ag-NPs show markedly reduced cycle-to-cycle variability of the high-resistance state, as confirmed by Weibull analysis, indicating improved endurance and switching reproducibility. Within a filamentary RS framework, we attribute this behavior to local metallization of the top interface by AgNPs, which partially inhibit OV transport and confines the RS dynamics to the bottom interface. Numerical simulations with the Oxygen Vacancy Resistive Network (OVRN) model succesfully reproduce the experimental HSLs, statistical trends, and tunable ON/OFF ratios with AgNPs coverage. These findings demonstrate that targeted interface metallization via metallic nanoparticles provides an effective route to control multi-interface RS dynamics and improve switching stability in without modifying the oxide architecture.
Paper Structure (5 sections, 4 equations, 6 figures, 2 tables)

This paper contains 5 sections, 4 equations, 6 figures, 2 tables.

Table of Contents

  1. INTRODUCTION
  2. Methods
  3. Experimental Characterization and electrical response
  4. MODELLING
  5. DISCUSSION AND CONCLUSIONS

Figures (6)

  • Figure 1: a) STEM-HAADF cross-sectional image of a device with Ag nanoparticles (AgNPs) embedded in the top electrode. The active zone of the device togheter with the top, central and bottom interfaces (TI, C and BI respectively) are zoomed in by the green and violet rectangles, respectively. See text for details. EDS linescans of the device taken along the orange line. Ta, O, Pt and Ag species are quantified: b) Without AgNPs, c) With AgNPs.
  • Figure 2: Electrical characterization of TaO$_x$ devices with (w) and without (wo) Ag nanoparticles (AgNPs). Measured individual hysteresis switching loops (HSL) (light blue lines) and average (Avg) HSL. Arrows indicate the circulation direction. a) Table with legs HSL in a device wo AgNPs. b) Counter-clockwise HSL wo AgNPs. c) Clockwise HSL wo AgNPs. d) Clockwise HSL in a device w AgNPs. e) Clockwise HSL for devices wo and w AgNPs.
  • Figure 3: a) Retentivity test showing all resistive levels. b) Cumulative probability distribution function (CP) obtained as a result of 500 ON/OFF cycles for devices wo and w AgNPs. c) Linear Weibull fittings (dashed lines) of $\ln (-\ln (1- CP))$ vs $\ln(R)$ for each of the resistive levels of devices with and without AgNPs. See text for details.
  • Figure 4: Scheme of the device with the active region for RS- comprising the TI, C and BI -enclosed by the violet rectangle. a) Without NPs:OV filaments bridge the Ta$_2$O$_5$ layer (LR state). When an external stimulus is applied, these filaments retract/grow at the TI/BI interfaces (HR1 and HR2 states). b) With AgNPs: RS is mostly restricted to the BI, giving a single CW cycle. See text for details.
  • Figure 5: Top panels: Average experimental (solid lines) and simulated (dashed line) HSLs for the device without NPs. a) TWL, b) CCW and c) CW, HSLs. d) OV concentration (upper panel) and resistivity profiles (bottom panel) near the TI and BI, for the LR (left panels), HR1 (central panels) and HR2 (right panels) resistance states indicated in a) and b).
  • ...and 1 more figures