Van der Waals Engineering of One-Transistor-One-Ferroelectric-Memristor Architecture for an Energy-Efficient Neuromorphic Array.

Two-dimensional-material-based memristor arrays hold promise for data-centric applications such as artificial intelligence and big data. However, accessing individual memristor cells and effectively controlling sneak current paths remain challenging. Here, we propose a van der Waals engineering approach to create one-transistor-one-memristor (1T1M) cells by assembling the emerging two-dimensional ferroelectric CuCrPS with MoS and -BN.

Balancing Surface Chemistry and Flake Size of MXene-Based Electrodes for Bioelectrochemical Reactors.

MXenes have excellent properties as electrode materials in energy storage devices or fuel cells. In bioelectrochemical systems (for wastewater treatment and energy harvesting), MXenes can have antimicrobial characteristics in some conditions. Here, different intercalation and delamination approaches to obtain TiCT MXene flakes with different terminal groups and lateral dimensions are comprehensively investigated.

Ultraflat Cu(111) foils by surface acoustic wave-assisted annealing.

Ultraflat metal foils are essential for semiconductor nanoelectronics applications and nanomaterial epitaxial growth. Numerous efforts have been devoted to metal surface engineering studies in the past decades. However, various challenges persist, including size limitations, polishing non-uniformities, and undesired contaminants.

Intertwined Flexoelectricity and Stacking Ferroelectricity in Marginally Twisted hBN Moiré Superlattice.

Moiré superlattices in twisted van der Waals homo/heterostructures present a fascinating interplay between electronic and atomic structures, with potential applications in electronic and optoelectronic devices. Flexoelectricity, an electromechanical coupling between electric polarization and strain gradient, is intrinsic to these superlattices because of the lattice misfit strain at the atomic scale. However, due to its weak magnitude, the effect of flexoelectricity on moiré ferroelectricity has remained underexplored.

The Effect of Relative Humidity in Conductive Atomic Force Microscopy.

Conductive atomic force microscopy (CAFM) analyzes electronic phenomena in materials and devices with nanoscale lateral resolution, and it is widely used by companies, research institutions, and universities. Most data published in the field of CAFM is collected in air at a relative humidity (RH) of 30-60%. However, the effect of RH in CAFM remains unclear because previous studies often made contradictory claims, plus the number of samples and locations tested is scarce.

Wafer-Scale Transfer of MXene Films with Enhanced Device Performance via 2D Liquid Intercalation.

Wafer-scale transfer processes of 2D materials significantly expand their application space in scalable microelectronic devices with excellent and tunable properties through van der Waals (vdW) stacking. Unlike many 2D materials, wafer-scale transfer of MXene films for vdW contact engineering has not yet been reported. With their rich surface chemistry and tunable properties, the transfer of MXenes can enable enormous possibilities in electronic devices using interface engineering.

Tuning Hole-Injection in Organic-Light Emitting Diodes with Self-Assembled Monolayers.

Improving hole injection through the surface modification of indium tin oxide (ITO) with self-assembled monolayers (SAMs) is a promising method for modulating the carrier injection in organic light-emitting diodes (OLEDs). However, developing SAMs with the required characteristics remains a daunting challenge. Herein, we functionalize ITO with various phosphonic acid SAMs and evaluate the SAM-modified anodes in terms of their work function (WF), molecular distribution, coverage, and electrical conductivity.

7D High-Dynamic Spin-Multiplexing.

Multiplexing technology creates several orthogonal data channels and dimensions for high-density information encoding and is irreplaceable in large-capacity information storage, and communication, etc. The multiplexing dimensions are constructed by light attributes and spatial dimensions. However, limited by the degree of freedom of interaction between light and material structure parameters, the multiplexing dimension exploitation method is still confused.

On the quality of commercial chemical vapour deposited hexagonal boron nitride.

The semiconductors industry has put its eyes on two-dimensional (2D) materials produced by chemical vapour deposition (CVD) because they can be grown at the wafer level with small thickness fluctuations, which is necessary to build electronic devices and circuits. However, CVD-grown 2D materials can contain significant amounts of lattice distortions, which degrades the performance at the device level and increases device-to-device variability. Here we statistically analyse the quality of commercially available CVD-grown hexagonal boron nitride (h-BN) from the most popular suppliers.

Programmable Optoelectronic Synaptic Transistors Based on MoS/TaNiS Heterojunction for Energy-Efficient Neuromorphic Optical Operation.

The optoelectronic synaptic transistors with various functions, broad spectral perception, and low power consumption are an urgent need for the development of advanced optical neural network systems. However, it remains a great challenge to realize the functional diversification of the systems on a single device. 2D van der Waals (vdW) materials can combine unique properties by stacking with each other to form heterojunctions, which may provide a strategy for solving this problem.

Thermal Compact Modeling and Resistive Switching Analysis in Titanium Oxide-Based Memristors.

Resistive switching devices based on the Au/Ti/TiO/Au stack were developed. In addition to standard electrical characterization by means of - curves, scanning thermal microscopy was employed to localize the hot spots on the top device surface (linked to conductive nanofilaments, CNFs) and perform in-operando tracking of temperature in such spots. In this way, electrical and thermal responses can be simultaneously recorded and related to each other.

Nonepitaxial Wafer-Scale Single-Crystal 2D Materials on Insulators.

Next-generation nanodevices require 2D material synthesis on insulating substrates. However, growing high-quality 2D-layered materials, such as hexagonal boron nitride (hBN) and graphene, on insulators is challenging owing to the lack of suitable metal catalysts, imperfect lattice matching with substrates, and other factors. Therefore, developing a generally applicable approach for realizing high-quality 2D layers on insulators remains crucial, despite numerous strategies being explored.

High-performance van der Waals antiferroelectric CuCrPS-based memristors.

Layered thio- and seleno-phosphate ferroelectrics, such as CuInPS, are promising building blocks for next-generation nonvolatile memory devices. However, because of the low Curie point, the CuInPS-based memory devices suffer from poor thermal stability (<42 °C). Here, exploiting the electric field-driven phase transition in the rarely studied antiferroelectric CuCrPS crystals, we develop a nonvolatile memristor showing a sizable resistive-switching ratio of ~ 1000, high switching endurance up to 20,000 cycles, low cycle-to-cycle variation, and robust thermal stability up to 120 °C.

Current-Limited Conductive Atomic Force Microscopy.

Conductive atomic force microscopy (CAFM) has become the preferred tool of many companies and academics to analyze the electronic properties of materials and devices at the nanoscale. This technique scans the surface of a sample using an ultrasharp conductive nanoprobe so that the contact area between them is very small (<100 nm) and it can measure the properties of the sample with a very high lateral resolution. However, measuring relatively low currents (∼1 nA) in such small areas produces high current densities (∼1000 A/cm), which almost always results in fast nanoprobe degradation.

Anisotropic Superconducting Nb CT MXene Processed by Atomic Exchange at the Wafer Scale.

Superconductivty has recently been induced in MXenes through surface modification. However, the previous reports have mostly been based on powders or cold-pressed pellets, with no known reports on the intrinsic superconsucting properties of MXenes at the nanoale. Here, it is developed a high-temperature atomic exchange process in NH atmosphere which induces superconductivity in either singleflakes or thin films of Nb CT MXene.

Spatially-Resolved Thermometry of Filamentary Nanoscale Hot Spots in TiO Resistive Random Access Memories to Address Device Variability.

Resistive random access memories (RRAM), based on the formation and rupture of conductive nanoscale filaments, have attracted increased attention for application in neuromorphic and in-memory computing. However, this technology is, in part, limited by its variability, which originates from the stochastic formation and extreme heating of its nanoscale filaments. In this study, we used scanning thermal microscopy (SThM) to assess the effect of filament-induced heat spreading on the surface of metal oxide RRAMs with different device designs.

Recent Advances and Future Prospects for Memristive Materials, Devices, and Systems.

Memristive technology has been rapidly emerging as a potential alternative to traditional CMOS technology, which is facing fundamental limitations in its development. Since oxide-based resistive switches were demonstrated as memristors in 2008, memristive devices have garnered significant attention due to their biomimetic memory properties, which promise to significantly improve power consumption in computing applications. Here, we provide a comprehensive overview of recent advances in memristive technology, including memristive devices, theory, algorithms, architectures, and systems.

Inkjet-printed h-BN memristors for hardware security.

Inkjet printing electronics is a growing market that reached 7.8 billion USD in 2020 and that is expected to grow to ∼23 billion USD by 2026, driven by applications like displays, photovoltaics, lighting, and radiofrequency identification. Incorporating two-dimensional (2D) materials into this technology could further enhance the properties of the existing devices and/or circuits, as well as enable the development of new concept applications.

Cellular automata imbedded memristor-based recirculated logic in-memory computing.

Memristor-based circuits offer low hardware costs and in-memory computing, but full-memristive circuit integration for different algorithm remains limited. Cellular automata (CA) has been noticed for its well-known parallel, bio-inspired, computational characteristics. Running CA on conventional chips suffers from low parallelism and high hardware costs.

Solid Platinum Nanoprobes for Highly Reliable Conductive Atomic Force Microscopy.

Conductive atomic force microscopy (CAFM) is a powerful technique to investigate electrical and mechanical properties of materials and devices at the nanoscale. However, its main challenge is the reliability of the probe tips and their interaction with the samples. The most common probe tips used in CAFM studies are made of Si coated with a thin (∼20 nm) film of Pt or Pt-rich alloys (such as Pt/Ir), but this can degrade fast due to high current densities (>10A/cm) and mechanical frictions.

Holistic Variability Analysis in Resistive Switching Memories Using a Two-Dimensional Variability Coefficient.

We present a new methodology to quantify the variability of resistive switching memories. Instead of statistically analyzing few data points extracted from current versus voltage (-) plots, such as switching voltages or state resistances, we take into account the whole - curve measured in each RS cycle. This means going from a one-dimensional data set to a two-dimensional data set, in which every point of each - curve measured is included in the variability calculation.

Nanoscale temperature sensing of electronic devices with calibrated scanning thermal microscopy.

Heat dissipation threatens the performance and lifetime of many electronic devices. As the size of devices shrinks to the nanoscale, we require spatially and thermally resolved thermometry to observe their fine thermal features. Scanning thermal microscopy (SThM) has proven to be a versatile measurement tool for characterizing the temperature at the surface of devices with nanoscale resolution.