High‐Speed Ionic Synaptic Memory Based on 2D Titanium Carbide MXene

Abstract

Synaptic devices with linear high‐speed switching can accelerate learning in artificial neural networks (ANNs) embodied in hardware. Conventional resistive memories however suffer from high write noise and asymmetric conductance tuning, preventing parallel programming of ANN arrays. Electrochemical random‐access memories (ECRAMs), where resistive switching occurs by ion insertion into a redox‐active channel, aim to address these challenges due to their linear switching and low noise. ECRAMs using 2D materials and metal oxides however suffer from slow ion kinetics, whereas organic ECRAMs enable high‐speed operation but face challenges toward on‐chip integration due to poor temperature stability of polymers. Here, ECRAMs using 2D titanium carbide (Ti3C2Tx) MXene that combine the high speed of organics and the integration compatibility of inorganic materials in a single high‐performance device are demonstrated. These ECRAMs combine the speed, linearity, write noise, switching energy, and endurance metrics essential for parallel acceleration of ANNs, and importantly, they are stable after heat treatment needed for back‐end‐of‐line integration with Si electronics. The high speed and performance of these ECRAMs introduces MXenes, a large family of 2D carbides and nitrides with more than 30 stoichiometric compositions synthesized to date, as promising candidates for devices operating at the nexus of electrochemistry and electronics.

Guidelines for Synthesis and Processing of Chemically Stable Two-Dimensional V2CTx MXene

“…Since their discovery in 2011, two-dimensional (2D) transition metal carbides and nitrides, MXenes, have shown promising electrical, mechanical, optical, and electrochemical properties leading to their widespread use in applications such as energy storage, electromagnetic interference shielding, , sensing, , electronics, , and biomedicine, − to name a few. MXenes have a general formula of M n +1 X n T x , where M represents early transition metals (Ti, V, Nb, etc.…”

Tunable Resistive Switching in 2D MXene Ti3C2 Nanosheets for Non-Volatile Memory and Neuromorphic Computing

“…In addition, memristors based on 2D materials can truly achieve nanoscale dimension and even a single atomic layer, contributing to low power consumption, gate tunability, and mechanical flexibility. , Furthermore, such memristors based on 2D materials are applicable to the artificial synapses for brain-inspired neuromorphic computing. , Ti 3 C 2 , as a well-studied 2D material in the MXene family, has been widely used in supercapacitors, batteries, catalysts, , and biosensors . In recent years, studies of Ti 3 C 2 in memristors and memristor-based artificial synapses have gradually emerged owing to its outstanding electric properties and diverse structures, , but the research is still limited compared to other classes of nanomaterials. Analog RS behaviors and basic synaptic functions were reported in Cu/Ti 3 C 2 /Cu memristors .…”

“…13,14 Ti 3 C 2 , as a wellstudied 2D material in the MXene family, has been widely used in supercapacitors, 15 batteries, 16 catalysts, 17,18 and biosensors. 19 In recent years, studies of Ti outstanding electric properties and diverse structures, 20,21 but the research is still limited compared to other classes of nanomaterials. Analog RS behaviors and basic synaptic functions were reported in Cu/Ti 3 C 2 /Cu memristors.…”

Ultralow-Power RRAM with a High Switching Ratio Based on the Large van der Waals Interstice Radius of TMDs

“…Graphene, − transitional-metal dichalcogenides (TMDs), − transition-metal carbides and nitrides (MXenes), hexagonal boron nitride (hBN) and semiconductor polymers , are two-dimensional (2D) storage materials discovered in recent years that can be used to fabricate not only rigid RRAM but also flexible RRAM. RRAM based on a 2D material storage layer − , shows better performance potential than that based on oxide materials. ,,,− The performance index of RRAM based on 2D materials developed in just over 10 years (solid blue dots − , in Figure S1) has caught up with that based on oxide materials (hollow violet dots ,,,− in Figure S1), which have been investigated for 60 years.…”

“…Moreover, TMO storage materials have the problem of insufficient ductility. Graphene, 24−35 transitional-metal dichalcogenides (TMDs), 36−40 transition-metal carbides and nitrides (MXenes), 41 hexagonal boron nitride (hBN) 42 and semiconductor polymers 43,44 are two-dimensional (2D) storage materials discovered in recent years that can be used to fabricate not only rigid RRAM but also flexible RRAM. RRAM based on a 2D material storage layer [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]43 shows better performance potential than that based on oxide materials.…”