Copper indium thiophosphate, CuInP2S6, has attracted much attention in recent years due to its van der Waals layered structure and robust ferroelectricity at room temperature. In this review, we aim to give an overview of the various properties of CuInP2S6, covering structural, ferroelectric, dielectric, piezoelectric and transport properties, as well as its potential applications. We also highlight the remaining questions and possible research directions related to this fascinating material and other compounds of the same family.

Van der Waals layered ferroelectric CuInP 2 S 6 : Physical properties and device applications

Device applications of ferroelectrics have not only utilized the switchable polarization but also adopted myriads of emerging physical properties In particular, ferroelectrics in ultra-thin limit have recently attracted considerable scientific and technological interest owing to the increasing demand for miniaturization of electronic devices In the last two decades, ultra-thin ferroelectrics have rapidly developed with the advances in the theoretical calculations, synthesis, and characterization techniques However, atomic-scale realization and rigorous characterization of ultra-thin ferroelectricity remain challenging In this review, we summarize state-of-the-art researches on ultra-thin ferroelectrics We provide a brief overview of the history and underlying mechanism of ferroelectrics in the context of ultra-thin ferroelectrics In particular, we discuss complex transition metal oxide ultra-thin ferroelectrics, ferroelectric two-dimensional materials, and fluorite HfO2-based ultra-thin ferroelectrics Further, we discuss the characterization techniques used to verify the ultra-thin limit of ferroelectricity, followed by device applications based on various emergent properties of ultra-thin ferroelectrics Finally, we provide a brief conclusion and outlook

Ultra-thin ferroelectrics

Channel current conduction modulation with the spontaneous polarization of ferroelectric films in ferroelectric field-effect transistors (FeFETs) has been widely investigated. Low interface quality and thermodynamic instability owing to the presence of dangling bonds in the conventional ferroelectrics have limited the memory retention and endurance of FeFETs. This, in turn, prevents their commercialization. However, the atomically thin nature of 2D ferroelectric, semiconducting, and insulating films facilitate the achievement of trap-free interfaces as van der Waal heterostructures (vdWHs) to develop FeFETs with long data retention and endurance characteristics. Here, we demonstrate a 2D vdWH FeFET fabricated with ferroelectric CuInP2S6 (CIPS), hexagonal boron nitride (h-BN) as the dielectric, and InSe as the ferroelectric semiconductor channel. The device shows an excellent performance as nonvolatile memory (NVM) with its large memory window (4.6 V at a voltage sweep of 5 V), high drain current on/off ratio (>104), high endurance, and long data retention (>104 s). These results demonstrate the considerable potential of vdWHs for the development of FeFETs for logic and NVM applications.

Two-Dimensional CIPS-InSe van der Waal Heterostructure Ferroelectric Field Effect Transistor for Nonvolatile Memory Applications.

Van der Waals layered CuInP2S6 (CIPS) is an ideal candidate for developing two-dimensional microelectronic heterostructures because of its room temperature ferroelectricity, although field-driven polarization reversal of CIPS is intimately coupled with ionic migration, often causing erratic and damaging switching that is highly undesirable for device applications. In this work, we develop an alternative switching mechanism for CIPS using flexoelectric effect, abandoning external electric fields altogether, and the method is motivated by strong correlation between polarization and topography variation of CIPS. Phase-field simulation identifies a critical radius of curvature around 5 μm for strain gradient to be effective, which is realized by engineered topographic surfaces using silver nanowires and optic grating upon which CIPS is transferred to. We also demonstrate mechanical modulation of CIPS on demand via strain gradient underneath a scanning probe, making it possible to engineer multiple polarization states of CIPS for device applications.

https://www.science.org/doi/pdf/10.1126/sciadv.abq1232?download=true

Flexoelectric engineering of van der Waals ferroelectric CuInP2S6

Two-dimensional ferroelectrics have gained attention because of their unique ferroelectric properties, e.g., giant negative electrostriction, odd/even layer effect, intercorrelation of in-plane and out-of-plane ferroelectricity, ferroelectric metal nature or tunable quadruple-well ferroelectric property. Here, the interplay between ionic kinetics and ferroelectric switching properties is reported in a model system, CuInP2S6, one of the few van der Waals room-temperature ferroelectric crystals. An unconventional out-of-plane domain inversion phenomenon induced by an in-plane electric field has been observed and clarified experimentally. The intralayer hopping motions of Cu-ions can play a role as media of ferroelectric domain inversion. These findings not only provide direct evidence for the microscopic origin of ferroelectric polarization in CuInP2S6, but also establish a new mechanism to reverse ferroelectric dipoles simply and effectively, offering opportunities for both fundamental studies and new device applications in information and energy storage.

Unconventional out-of-plane domain inversion via in-plane ionic migration in a van der Waals ferroelectric

Two-dimensional (2D) ferroelectrics refer to those ferroelectrics with layered structure and weak interlayer interactions (e.g., van de Waals interlayer coupling). A number of basic physical issues in the framework of ferroelectricity deserve clarifications, and one of them is the size effect regarding the dependence of ferroelectricity on material thickness. In this work, we investigate the ferroelectric domain structures of 2D ferroelectric CuInP2S6 nanoflakes attached on heavily doped Si wafers and polarization switching using the piezoresponse force microscopy. While the domain structure shows highly irregular morphology and 180° domain walls, the statistics on domain size (diameter) W and nanoflake thickness d demonstrates the remarkable thickness dependence of domain size, illustrated by the shrinking domain size from 630 nm to 75 nm with decreasing thickness d from ∼130 nm to ∼11 nm. This dependence fits the Landau-Lifshitz-Kittel (LLK) scaling law with the scaling exponent of ∼0.65, slightly larger than 0.5 for 3D ferroelectrics. It is suggested that the size effect in terms of the LLK scaling law does not show an essential difference between the 2D and 3D ferroelectric systems.

Thickness dependence of domain size in 2D ferroelectric CuInP2S6 nanoflakes

BiFeO3 has been receiving continuous attention for its excellent ferroelectric and multiferroic properties. Nevertheless, the piezoelectricity as a complementary property of ferroelectricity remains less addressed for BiFeO3 at least in a single phase form. In this work, we investigate the piezoelectric behaviors of bulk Bi1−xNdxFeO3 ceramics, given that the Nd-substitution may trigger structural phase transitions from the R3c phase to the Pna21 phase and eventually toward the non-polar Pnma phase. It is revealed that the piezoelectric coefficient d33 does increase with the increasing Nd content x inside the R3c phase region. However, no d33-enhancement across the R3c–Pna21 boundary region and the Pna21–Pnma boundary region is identified, suggesting no positive correlation between the piezoelectric coefficient and the possible morphotropic phase boundaries. The observed d33-enhancement inside the R3c phase region should be attributed to the remarkably reduced domain size and release of pinned domain wall motion by defects.

/pdf/absence-of-piezoelectric-enhancement-around-the-morphotropic-2e2hcoqjhz.pdf

Absence of piezoelectric enhancement around the morphotropic phase boundaries for Bi1−xNdxFeO3 ceramics

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Xiangping Jiang

Author Tools

Chat about Author

Papers

Thickness dependence of domain size in 2D ferroelectric CuInP2S6 nanoflakes

Absence of piezoelectric enhancement around the morphotropic phase boundaries for Bi1−xNdxFeO3 ceramics