A Low‐Current and Analog Memristor with Ru as Mobile Species

Abstract

The switching parameters and device performance of memristors are predominately determined by their mobile species and matrix materials. Devices with oxygen or oxygen vacancies as the mobile species usually exhibit a great retention but also need a relatively high switching current (e.g., >30 µA), while devices with Ag or Cu as cation mobile species do not require a high switching current but usually show a poor retention. Here, Ru is studied as a new type of mobile species for memristors to achieve low switching current, fast speed, good reliability, scalability, and analog switching property simultaneously. An electrochemical metallization‐like memristor with a stack of Pt/Ta2O5/Ru is developed. Migration of Ru ions is revealed by energy‐dispersive X‐ray spectroscopy mapping and in situ transmission electron microscopy within a sub‐10 nm active device area before and after switching. The results open up a new avenue to engineer memristors for desired properties.

Filament‐Free Bulk Resistive Memory Enables Deterministic Analogue Switching

“…[ 4 ] Neuromorphic computing architectures for fully connected [ 5–7 ] and convolutional [ 8,9 ] neural networks have been developed. Despite significant research into memory technologies such as conductive‐bridge random access memory, [ 10–12 ] ferroelectric memory, [ 13 ] phase‐change memory, [ 14–16 ] among others, the search for a CMOS compatible analogue non‐volatile memory element, or artificial synapse, with accurate and efficient switching has been elusive.…”

Polydopamine Film Self‐Assembled at Air/Water Interface for Organic Electronic Memory Devices

“…In recent years, memristive devices, also known as resistance switching devices, have shown great potentials in various fields, including non‐volatile memory, reconfigurable switches, bio‐inspired neuromorphic computing, and radiofrequency switches, for their intrinsic properties of low power consumption, fast switching speed, high endurance, and reliable retention. [ 1–5 ] Typically, memristive devices are constructed with a relatively simple structure of metal/insulator/metal configuration, which can work under two main mechanisms. For example, the formation and dissolution of metallic filaments (e.g., Cu or Ag) are responsible for the low and high resistance states in the electrochemical metallization memory systems.…”

Nanometer‐Scale Uniform Conductance Switching in Molecular Memristors

“…[ 9 ] In fact, the issue of nonuniformity and stochasticity is not only specific to oxides but is common in other genres of memristors like phase change memories, [ 10 ] nitrides, [ 11 ] or those working on metal‐ion migration. [ 12–14 ] One of the problematic features inherent to any filamentary mechanism is electroforming, which is the first‐time switching process involving dissolution, injection, and orientation of the active conducting atoms/ions into the dielectric layer. [ 7,15–17 ] The forming process usually requires much higher voltage and current than the reading/writing processes, resulting in high power dissipation and local heating that can damage the device and local circuitry.…”

“…[ 26 ] For memristors working on metal ion migration, there are several reports attempting in situ TEM measurements. [ 13,15 ] The most conclusive picture is presented in the paper by Yang et al. capturing the formation and dynamics of metallic filaments both in planar and vertical structures.…”

“…[26] For memristors working on metal ion migration, there are several reports attempting in situ TEM measurements. [13,15] The most conclusive picture is presented in the paper by Yang et al capturing the formation and dynamics of metallic filaments both in planar and vertical structures. [15] Thus, while there are conclusive evidences of filamentary or localized switching mechanisms, a demonstration of nanoscopic homogeneous switching is missing.…”