Author(s): Chao Liu, Wei Ren, and Silvia Picozzi
Driven by the expected contribution of two-dimensional multiferroic systems with strong magnetoelectric coupling to the development of multifunctional nanodevices, here we propose, by means of first-principles calculations, vanadium-halide monolayers as a new class of spin-chirality-driven van der W…
[Phys. Rev. Lett. 132, 086802] Published Fri Feb 23, 2024
Two-dimensional (2D) materials that combine ferromagnetic, semiconductor, and piezoelectric properties hold significant potential for both fundamental research and spin electronic devices. However, the majority of reported 2D ferromagnetic-semiconductor-piezoelectric materials rely on d-electron systems, which limits their practical applications due to a Curie temperature lower than room temperature (RT). Here, we report a high-crystallinity carbon nitride (CCN) material based on sp-electrons using a chemical vapor deposition strategy. CCN exhibits a band gap of 1.8 eV and has been confirmed to possess substantial in-plane and out-of-plane piezoelectricity. Moreover, we acquired clear evidences of ferromagnetic behavior at room temperature. Extensive structural characterizations combined with theoretical calculations reveal that incorporating structural oxygen into the highly ordered heptazine structure causes partial substitution of nitrogen sites, which is primarily responsible for generating room-temperature ferromagnetism and piezoelectricity. As a result, the strain in wrinkles can effectively modulate the domain behavior and piezoelectric potential at room temperature. The addition of RT ferromagnetic-semiconductor-piezoelectric material based on sp-electrons to the family of two-dimensional materials opens up numerous possibilities for novel applications in fundamental research and spin electronic devices.
Nature Reviews Materials, Published online: 23 February 2024; doi:10.1038/s41578-024-00663-4
An article in Matter uses rice grains as scaffolds for cultivated beef cells to produce an innovative beef-infused rice.
An innovative methodology is developed to craft high-quality complex heterostructures on Si, seamlessly integrated with SrTiO3 membranes. A diverse array of complex heterostructures has been successfully fabricated, and their superior quality and enhanced functionality have been rigorously validated through comprehensive angle-resolved photoemission spectroscopy. This groundbreaking approach paves the way for the advancement of electronic devices and presents exciting prospects for the straightforward integration of multifunctional quantum physical properties into Si-based platforms.
The integration of complex oxides with a wide range of functionalities on conventional semiconductor platforms is highly demanded for functional applications. Despite continuous efforts to integrate complex oxides on Si, it is still challenging to harvest epitaxial layers using standard deposition processes. Here, a novel method is demonstrated to create high-quality complex heterostructures on Si integrated with SrTiO3 membranes as a universal platform. The STO membrane successfully bridges a broad spectrum of complex heterostructures such as SrNbO3, SrVO3, TiO2, and dichalcogenide 2D superconducting FeSe toward semiconducting wafers (Si). Through electronic structures measured by angle-resolved photoemission spectroscopy, the high quality and functionality of the heterostructures are verified. This study demonstrated a new pathway toward realizing electronic devices with multifunctional physical properties incorporated into Si.
To achieve the short-wave infrared polarization-sensitive photodetectors, vertical β-In2Se3/Te heterojunction is assembled. Due to the type-II band alignment and photo-gating effect, the heterojunction exhibits excellent responsivity (2 A/W at 1310 nm and 0.71 A/W at 1550 nm). Moreover, the device demonstrates superior polarization sensitivity with anisotropic photocurrent ratio of ≈4.95 in 1310 nm, which paves the way for polarimetric imaging.
Polarization-sensitive infrared photodetectors have vast application prospects in imaging systems and polarization sensors due to the addition of new detection dimensions beyond wavelength and intensity. However, most polarization-sensitive photodetectors are operated in the visible wavelength range and still encounter challenges of limited responsivity (R) and polarization ratio (PR) under short-wave infrared illumination. To address these issues, a vertical heterostructure of β-In2Se3-on-Te is reported, achieving high-performance and polarization-sensitive imaging sensors in the short-wave infrared (SWIR) region. The high R (2 A/W at 1310 nm and 0.71 A/W at 1550 nm) and specific detectivity (2.14 × 109 Jones at 1310 nm and 7.3 × 108 at 1550 nm) are obtained, which surpasses most photodetectors using anisotropic 2D material in the infrared range. Considering the strong anisotropic nature of Te nanosheets, the device exhibits notable polarization sensitivity with a PR value of 4.95 under 1310 nm laser irradiation. This work proposes a multifunctional photodetector for the great applications of ASCII code transmission and polarization-sensitive infrared imaging, offering a new opportunity for versatile angle-resolved optoelectronics in the infrared communication band.
Several methods are proposed to combat the ever-growing issue of counterfeit products in today's market. Carbon dots (CDs) are an attractive solution, as an environment-friendly answer, and also contribute to the circular economy. This review aims to highlight CDs’ luminescence tunability and their photo-chemical and photophysical responsive properties to make them relevant for anticounterfeiting and information encryption applications.
Counterfeit products and data vulnerability present significant challenges in contemporary society. Hence, various methods and technologies are explored for anticounterfeiting encoding, with luminescent tracers, particularly luminescent carbon dots (CDs), emerging as a notable solution. CDs offer promising contributions to product security, environmental sustainability, and the circular economy. This critical review aims to highlight the luminescence responsiveness of CDs to physical and chemical stimuli, achieved through nanoengineering their chemical structure. The discussion will delve into the various tunable luminescence mechanisms and decay times of CDs, investigating preferential excitations such as up-conversion, delayed fluorescence, fluorescence, room temperature phosphorescence, persistent luminescence, energy and charge transfer, as well as photo-chemical interactions. These insights are crucial for advancing anticounterfeiting solutions. Following this exploration, a systematic review will focus on the research of luminescent CDs' smart encoding applications, encompassing anticounterfeiting, product tracing, quality certification, and information encryption. Finally, the review will address key challenges in implementing CDs-based technology, providing specific insights into strategies aimed at maximizing their stability and efficacy in anticounterfeiting encoding applications.
One-nanometer-level thickness controllability in preparing sub-20-nm-thin lamellae for aberration-corrected STEM investigations is demonstrated. FIB/SEM quantifies the lamella thickness between 0 and 100 nm by back-scattered-electron SEM imaging. The thickness quantification provides real-time feedback on the autonomous termination of an FIB thinning process. Our methodology offers robust and operator-independent preparation of thin lamellae from various materials, including heterostructural materials.
Aberration-corrected scanning transmission electron microscopy (STEM) has been advancing resolution, sensitivity, and microanalysis due to the intense demands of atomic-level microstructural investigations. Recent STEM technologies require preparing a thin lamella whose thickness is ideally below 20 nm. Although focused-ion-beam/scanning-electron-microscopy (FIB/SEM) is an established method to prepare a high-quality lamella, nanometer-level controllability of lamella thickness remains a fundamental problem. Here, the robust preparation of a sub-20-nm-thin lamella is demonstrated by FIB/SEM with real-time feedback from thickness quantification. The lamella thickness is quantified by back-scattered-electron SEM imaging in a thickness range between 0 and 100 nm without any reference to numerical simulation. Using real-time feedback from the thickness quantification, the FIB/SEM terminates thinning a lamella at a targeted thickness. The real-time feedback system eventually provides 1-nm-level controllability of the lamella thickness. As a proof-of-concept, a near-10-nm-thin lamella is prepared from a SrTiO3 crystal by our methodology. Moreover, the lamella thickness is controllable at a target heterointerface. Thus, a sub-20-nm-thin lamella is prepared from a LaAlO3/SrTiO3 heterointerface. The methodology offers a robust and operator-independent platform to prepare a sub-20-nm-thin lamella from various materials. This platform will broadly impact aberration-corrected STEM studies in materials science and the semiconductor industry.
Nature Electronics, Published online: 21 February 2024; doi:10.1038/s41928-024-01127-x
Micropatterning of organic semiconductors by electron-beam exposure can be used to create vertical organic electrochemical transistor arrays and complementary logic circuits with densities of up to 7.2 million transistors per cm2.
Nature, Published online: 21 February 2024; doi:10.1038/s41586-023-07010-7
Integer and fractional quantum anomalous Hall effects in a rhombohedral pentalayer graphene–hBN moiré superlattice are observed, providing an ideal platform for exploring charge fractionalization and (non-Abelian) anyonic braiding at zero magnetic field.Nature, Published online: 21 February 2024; doi:10.1038/s41586-024-07076-x
A germanium–silicon single-photon avalanche diode operated at room temperature shows a noise-equivalent power improvement over the previous Ge-based single-photon avalanche diodes by 2–3.5 orders of magnitude.
A high-throughput colloidal printing strategy for fabricating large-area and uniform semiconductor nanofilms on freeform surfaces. Uniform deposition relies on the discovery of unprecedented enhanced thermal Marangoni flows of well-dispersed nanosheet colloid during the print-heating process that suppresses outward capillary flows.
The semiconductor thin film engineering technique plays a key role in the development of advanced electronics. Printing uniform nanofilms on freeform surfaces with high efficiency and low cost is significant for actual industrialization in electronics. Herein, a high-throughput colloidal printing (HTCP) strategy is reported for fabricating large-area and uniform semiconductor nanofilms on freeform surfaces. High-throughput and uniform printing rely on the balance of atomization and evaporation, as well as the introduced thermal Marangoni flows of colloidal dispersion, that suppresses outward capillary flows. Colloidal printing with in situ heating enables the fast fabrication of large-area semiconductor nanofilms on freeform surfaces, such as SiO2/Si, Al2O3, quartz glass, poly(ethylene terephthalate) (PET), Al foil, plastic tube, and Ni foam, expanding their technological applications where substrates are essential. The printed SnS2 nanofilms are integrated into thin-film semiconductor gas sensors with one of the fastest responses (8 s) while maintaining the highest sensitivity (R g /R a = 21) (toward 10 ppm NO2), as well as an ultralow limit of detection (LOD) of 46 ppt. The ability to print uniform semiconductor nanofilms on freeform surfaces with high-throughput promises the development of next-generation electronics with low cost and high efficiency.
A smart photoresponsive tongue is constructed by ternary co-assembly of phosphors, Tb3+ and HOFs. The sensor with fluorescence and phosphorescence dual-output signals can discriminate six kinds of umami, sour, and bitter compounds.
Artificial tongues have attracted increasing attention for the perception abilities of five basic tastes. However, simple and versatile identification of different tastes is a formidable challenge for bionic taste sensor. Enriching photoluminescence mechanisms to improve possibilities of multiple optical responses is conducive to simplify the sensor array. Herein, a single sensor Tb@MCATMA (Tb@1) is developed displaying dual-emissions of both green fluorescence and deep-blue phosphorescence by ternary co-assembly of Tb3+, trimesic acid (TMA) and a 2D hydrogen-bonded organic framework of melamine and cyanuric acid, MCA HOF. This sensor is capable of imitating the human gustatory system to identify and discriminate umami (disodium 5′-inosinate and disodium 5′-guanylate), sour (citric acid and oxalic acid) and bitter (2-furaldehyde and 5-hydroxymethylfurfural) substances through the diverse photoresponsive modes. Upon excitation wavelength as additional variable, the sensor can further collect the individual “fingerprint information” of six analytes related to tastes and quantitatively detect them with high accuracy. Moreover, the sensing mechanism of each analyte is explored in detail and substantiate that the uniform photoresponsive modes elicited by distinct analytes stem from the shared sensing mechanism. This work provides a facile and powerful sensor platform for taste perception to develop artificial photoresponsive tongue applicable to bionic gustatory system.
Nature Synthesis, Published online: 22 February 2024; doi:10.1038/s44160-024-00485-w
The enantioselective synthesis of an inherently chiral molecular nanographene is demonstrated by precisely controlling the sequential generation of chiral elements in its structure. The final stereocontrolled graphitization step allows for the separate synthesis of both enantiomers, thus paving the way towards chirality controlled all-carbon nanographenes.Publication date: 20 March 2024
Source: Joule, Volume 8, Issue 3
Author(s): Kirstin Alberi, Joseph J. Berry, Jacob J. Cordell, Daniel J. Friedman, John F. Geisz, Ahmad R. Kirmani, Bryon W. Larson, William E. McMahon, Lorelle M. Mansfield, Paul F. Ndione, Michael Owen-Bellini, Axel F. Palmstrom, Matthew O. Reese, Samantha B. Reese, Myles A. Steiner, Adele C. Tamboli, San Theingi, Emily L. Warren
Nature Materials, Published online: 22 February 2024; doi:10.1038/s41563-024-01809-z
Angle-resolved transport measurements on twisted trilayer graphene reveal evidence for a variety of correlated states with spontaneous symmetry breaking, and offer evidence of momentum polarization.
Nature Electronics, Published online: 20 February 2024; doi:10.1038/s41928-024-01131-1
Imaging circuits in three dimensions
Front Cover
In article number 2300239, Wen, Tsang, and co-workers demonstrate the potential application of 2D-HfTe2 nanosheets in nonlinear optics and ultrafast photonics. By utilizing side-polished fiber-based HfTe2-saturable absorbers, a mode-locked laser with a pulsed width of 724 fs is realized at the second-lowest mode-locking threshold pump power, and a highly stable single-frequency fiber laser with ultranarrow linewidth is designed.
The ferroelectric HZO-based SnS2 analog synaptic FET exhibits polarization changes in response to electrical signals, altering its electrical characteristics. The resulting electrical characteristic changes of the transistor mimic neuronal behavior. Depending on the direction of polarization, the conductivity of the SnS2 channel changes, which is analogous to the inhibition or excitation of signal transmission by neurotransmitters in synapses.
In this study, the development and characterization of 2D ferroelectric field-effect transistor (2D FeFET) devices are presented, utilizing nanoscale ferroelectric HfZrO2 (HZO) and 2D semiconductors. The fabricated device demonstrated multi-level data storage capabilities. It successfully emulated essential biological characteristics, including excitatory/inhibitory postsynaptic currents (EPSC/IPSC), Pair-Pulse Facilitation (PPF), and Spike-Timing Dependent Plasticity (STDP). Extensive endurance tests ensured robust stability (107 switching cycles, 105 s (extrapolated to 10 years)), excellent linearity, and high G max/G min ratio (>105), all of which are essential for realizing multi-level data states (>7-bit operation). Beyond mimicking synaptic functionalities, the device achieved a pattern recognition accuracy of ≈94% on the Modified National Institute of Standards and Technology (MNIST) handwritten dataset when incorporated into a neural network, demonstrating its potential as an effective component in neuromorphic systems. The successful implementation of the 2D FeFET device paves the way for the development of high-efficiency, ultralow-power neuromorphic hardware which is in sub-femtojoule (48 aJ/spike) and fast response (1 µs), which is 104 folds faster than human synapse (≈10 ms). The results of the research underline the potential of nanoscale ferroelectric and 2D materials in building the next generation of artificial intelligence technologies.
Herein, a chemical vapor deposition method is reported to synthesize 2D CuCrSe2 single crystal. The ultrathin CuCrSe2 nanosheet exhibits a high Curie temperature T C of 800 K. The in-plane and out-of-plane ferroelectricity in 2D CuCrSe2 are characterized by piezo-response force microscopy measurements and confirmed by the lateral and vertical devices.
Ultrathin 2D ferroelectrics with high Curie temperature are critical for multifunctional ferroelectric devices. However, the ferroelectric spontaneous polarization is consistently broken by the strong thermal fluctuations at high temperature, resulting in the rare discovery of high-temperature ferroelectricity in 2D materials. Here, a chemical vapor deposition method is reported to synthesize 2D CuCrSe2 nanosheets. The crystal structure is confirmed by scanning transmission electron microscopy characterization. The measured ferroelectric phase transition temperature of ultrathin CuCrSe2 is about ≈800 K. Significantly, the switchable ferroelectric polarization is observed in ≈5.2 nm nanosheet. Moreover, the in-plane and out-of-plane ferroelectric response are modulated by different maximum bias voltage. This work provides a new insight into the construction of 2D ferroelectrics with high Curie temperature.
Nature Communications, Published online: 19 February 2024; doi:10.1038/s41467-024-45580-w
Here the authors experimentally realized a systematic approach to synthesize arbitrary-size two-dimensional all-band-flat photonic lattices, which pave a route for investigating flat-band related physics such as slow-light, nonlinear breathing, and dispersionless image transmission.State-of-the-art research on two-dimensional material-based memristive arrays is comprehensively reviewed.
Critical steps in achieving in-memory computing are identified and highlighted, covering material selection, device performance analysis, and array structure design.
Challenges in progressing from single-device characterization to array-level and system-level implementations are discussed, along with proposed solutions.
