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

Abstract

An artificial synapse is essential for neuromorphic computing which has been expected to overcome the bottleneck of the traditional von-Neumann system. Memristors can work as an artificial synapse owing to their tunable non-volatile resistance states which offer the capabilities of information storage, processing, and computing. In this work, memristors based on two-dimensional (2D) MXene Ti3C2 nanosheets sandwiched by Pt electrodes are investigated in terms of resistive switching (RS) characteristics, synaptic functions, and neuromorphic computing. Digital and analog RS behaviors are found to coexist depending on the magnitude of operation voltage. Digital RS behaviors with two resistance states possessing a large switching ratio exceeding 103 can be achieved under a high operation voltage. Analog RS behaviors with a series of resistance states exhibiting a gradual change can be observed at a relatively low operation voltage. Furthermore, artificial synapses can be implemented based on the memristors with the basic synaptic functions, such as long-term plasticity of long-term potentiation and depression and short-term plasticity of the paired-pulse facilitation and depression. Moreover, the “learning–forgetting” experience is successfully emulated based on the artificial synapses. Also, more importantly, the artificial synapses can construct an artificial neural network to implement image recognition. The coexistence of digital and analog RS behaviors in the 2D Ti3C2 nanosheets suggests the potential applications in non-volatile memory and neuromorphic computing, which is expected to facilitate simplifying the manufacturing complexity for complex neutral systems where analog and digital switching is essential for information storage and processing.

Chemical-vapor-deposited 2D VSe2 nanosheet with threshold switching behaviors for Boolean logic calculations and leaky integrate-and-fire functions

“…In recent years, a large number of artificial neurons and synapses have been successfully constructed based on memristors. 14,[34][35][36] Among them, LIF model has been widely studied as a spiking neuron in the ANN due to its simplicity, reliability, and capturing the biological dynamics. 1 The LIF neuron can be realized by using the fabricated TS device.…”

Contrasting analog and digital resistive switching memory characteristics in solution-processed copper(i) thiocyanate and its polymer electrolyte-based memristive devices

“…Very few reports on memristive systems have shown digital and analog RS memories together. [9][10][11] The simultaneous observation of digital and analog RS memory makes the CuSCN-based devices more versatile. To gain more insight into the RS behavior of the CuSCN-based devices, we carried out the electrical characterization of ITO/CuSCN/Cu devices with different CuSCN layer thicknesses prepared at 3000 and 5000 rpm of spin-coating.…”

“…42 For materials like MXene (Ti 3 C 2 ) and 1T-MoS 2 nanosheets, the role of electronic conductivity (due to electron or hole) in observing analog RS is already established. 10,39 Although we are ruling out the possibility of an ECM type of mechanism for RS in CuSCN, the role of copper ion (Cu + ) diffusion can't be completely played down if we are looking at the voltage range over which the RS is observed in these devices (with Au and Cu as a top electrode). Unlike the case of the copper top electrode, we could not observe the analog switching for lower voltage sweep (o1.0 V) with the gold top electrode.…”

“…Recent reports of RS devices show that digital RS memory characteristics can be repurposed to observe analog RS memory, and vice versa, simply by maneuvering the biasing conditions. [9][10][11] Such versatility in the memory characteristics of memristive devices widens their application potential from conventional digital storage to the implementation of neuromorphic computing hardware and mimicking biological synaptic memory. Furthermore, memristive devices also see many specialized niche applications with novel device architectures and by on-boarding them with other micro/nanodevices.…”

Conjugated Polymer-Functionalized 2D MXene Nanosheets for Nonvolatile Memory Devices with High Environmental Stability

“…In the past decade, people have been committed to developing resistive switching materials. For the MXene-based memory devices, − the active materials reported in the literature are mainly inorganic/organic species-doped MXenes. For example, Wang et al fabricated the Al/Ag-doped MXene Ti 3 C 2 /Pt electronic device that exhibited memristive performance .…”