Stimulated Ionic Telegraph Noise in Filamentary Memristive Devices

Abstract

Random telegraph noise is a widely investigated phenomenon affecting the reliability of the reading operation of the class of memristive devices whose operation relies on formation and dissolution of conductive filaments. The trap and the release of electrons into and from defects surrounding the filament produce current fluctuations at low read voltages. In this work, telegraphic resistance variations are intentionally stimulated through pulse trains in HfO 2 -based memristive devices. The stimulated noise results from the re-arrangement of ionic defects constituting the filament responsible for the switching. Therefore, the stimulated noise has an ionic origin in contrast to the electronic nature of conventional telegraph noise. The stimulated noise is interpreted as raising from a dynamic equilibrium establishing from the tendencies of ionic drift and diffusion acting on the edges of conductive filament. We present a model that accounts for the observed increase of noise amplitude with the average device resistance. This work provides the demonstration and the physical foundation for the intentional stimulation of ionic telegraph noise which, on one hand, affects the programming operations performed with trains of identical pulses, as for neuromorphic computing, and on the other hand, it can open opportunities for applications relying on stochastic processes in nanoscaled devices.

Non-linear Memristive Synaptic Dynamics for Efficient Unsupervised Learning in Spiking Neural Networks

“…Indeed, the non-linear cases reported in Figure 2 should be associated to different resolutions from a purely mathematical point of view. These considerations are completely independent from the effect of the noise and variability that unavoidably affect any real memristive device (Yu et al, 2013 ; Frascaroli et al, 2015 , 2018 ; Covi et al, 2016 ; Brivio et al, 2017 , 2019b ). The impact of noise and variability has been investigated for some specific networks and some applications, demonstrating a general tolerance of neuromorphic systems against memristive synapse variability and noise (Querlioz et al, 2013 ; Garbin et al, 2014 ; Burr et al, 2015 ; Covi et al, 2016 ; Bocquet et al, 2018 ).…”

A Consistent Model for Short-Term Instability and Long-Term Retention in Filamentary Oxide-Based Memristive Devices

“…Regardless of the numerous great properties of ReRAMs mentioned above, there are issues concerning the stability of the programmed states warding them from commercial breakthrough so far. − One challenge is short-term instability, also called read noise, limiting the read window, which separates the HRS and LRS. Here, program-verify or shaping algorithms were proposed to overcome these limitations but have been reported to not have a lasting effect .…”

Physics-based compact modelling of the analog dynamics of HfO x resistive memories

“…The RESET transition starts from about 0.55 V and gradually continues due to the set up of a negative thermal feedback and the attainment of an equilibrium between the drift and the diffusion of oxygen vacancies in the gap [7,23,32]. In particular, the diffusion process counteracts the drift, which tends to reduce the oxygen vacancies concentration [33]. Therefore, maximum and minimum concentration values have to be evaluated self-consistently through at least one complete SET and RESET cycle.…”