Jing Zhang

The review explores the influence of strain on semiconductor nanomembranes, emphasizing their tunable properties and potential applications in photonics and optoelectronics. It provides a detailed overview on various aspects of nanomembrane and demonstrates how strain enhances devices’ performance, like lasers, Light emitting diode (LED), photodetectors, and photonic crystal cavities, through improved material functionalities.

Abstract

When semiconductor crystals are made into the form of thin sheets, i.e., nanomembranes, their properties and behaviors may be remarkably different from their bulk counterparts. A plethora of fascinating science and important applications arise consequently, some of which are investigated in recent years, and there are still a lot more to be discovered in the future. Nanomembranes (NMs) provide a good platform for strain engineering and offer tremendous research opportunities in photonics and optoelectronics applications. Strain alters energy band line up of a material furthermore influencing its carrier mobility which impacts a wide range of applications. In this article, the strain-engineered NMs are reviewed using semiconductor materials as a model system for photonics and optoelectronics applications. While many fundamental aspects of NMs are discussed and outlined different methods for strain engineering of NM, the use of semiconductor NMs for photonics and optoelectronics applications is the locus of the present review article.

A unique type of surface states in a family of ternary rare-earth pnictide tellurides with robust band structure and sizeable spin splitting is realized. Spin ARPES measurements reveal high spin polarization and distinct spin-momentum locking texture, arising from local site asymmetry and surface-purified spin-orbital texture. This work presents an intriguing spin-orbital-momentum-layer locking phenomenon, shedding lights on potential spintronic applications.

Abstract

To generate and manipulate spin-polarized electronic states in solids are crucial for modern spintronics. The textbook routes employ quantum well states or Shockley/topological type surface states whose spin degeneracy is lifted by strong spin-orbit coupling and inversion symmetry breaking at the surface/interface. The resultant spin polarization is usually truncated because of the intertwining between multiple orbitals. Here a unique type of surface states is realized, namely, dangling bond surface states in a family of ternary rare-earth pnictide tellurides RePnTe (Re = La, Gd, Ce; Pn = Sb, Bi), with robust band structure and sizeable spin splitting. Spin and angle-resolved photoemission spectroscopy measurements reveal high spin polarization and distinct spin-momentum locking texture, which, according to the theoretical analysis, arise from local site asymmetry and surface-purified spin-orbital texture. The work extends the so-called “hidden spin polarization” from the bulk to the surface, presenting an intriguing spin-orbital-momentum-layer locking phenomenon, which may shed lights on potential spintronic applications.

A single-crystal α-Sb₂O₃ dielectric is synthesized by employing one-step chemical vapor deposition method. Dual-gate MoS₂ field-effect transistors are fabricated using α-Sb₂O₃, achieving a switching ratio exceeding 10⁸. Effective modulation of field-effect transistors using 2D metal oxides is successfully demonstrated. These findings provide a vital strategy for the optimization and integration of transistors.

Abstract

The remarkable potential of two-dimensional (2D) materials in sustaining Moore's law has sparked a research frenzy. Extensive efforts have been made in the research of utilizing 2D semiconductors as channel materials in field-effect transistors. However, the next generation of integrated devices requires the integration of gate dielectrics with wider bandgaps and higher dielectric constants. Here, insulating α-Sb₂O₃ single-crystal nanosheets are synthesized by one-step chemical vapor deposition method. Importantly, the α-Sb₂O₃ single-crystal dielectric exhibits a high dielectric constant of 11.8 and a wide bandgap of 3.78 eV. Besides, the atomically smooth interface between α-Sb₂O₃ and MoS₂ enables the fabrication of dual-gated field-effect transistors with the top gate dielectric of α-Sb₂O₃ nanosheets. The field-effect transistors exhibit a switching ratio of exceeding 10⁸, which achieves the manipulation of field-effect transistors by using 2D dielectric materials. These results hold significant implications for optimizing the performances of 2D devices and innovating microelectronics.

Nature Communications, Published online: 07 November 2024; doi:10.1038/s41467-024-53167-8

Publisher Correction: Free-standing two-dimensional ferro-ionic memristor

Nature, Published online: 06 November 2024; doi:10.1038/s41586-024-08156-8

Energy-efficient, solid-state amorphization of indium selenide nanowires is achieved using direct current, avoiding the melt–quench process.

Nature, Published online: 06 November 2024; doi:10.1038/s41586-024-07858-3

Methods to manufacture layered hybrid superlattices composed of alternating crystalline atomic layers and self-assembled atomic or molecular interlayers are described, to make use of their combined strengths and produce designable quantum solids.

Nature, Published online: 06 November 2024; doi:10.1038/s41586-024-08173-7

A modular autonomous platform for general exploratory synthetic chemistry uses mobile robots to integrate an automated synthesis platform and two analysis platforms.

A novel design and manufacturing approach for the realization of liquid crystal optical waveguides using photopatterning is presented. The method is used to demonstrate straight waveguides and curved waveguides. Experiments are supported with numerical simulations. Based on the presented design and manufacturing approach, liquid crystal optical waveguides of various shapes can be realized accurately with low-cost.

Abstract

A novel design and approach for the realization of liquid crystal optical waveguides using photopatterning as a manufacturing method is presented. The developed method is used to demonstrate straight waveguides of different widths and curved waveguides with different radius of curvature. The waveguides are terminated with +1 or −1 surface defects through which the light incouples/outcouples. The effect of the straight waveguide thickness and the radius of curvature of the curved waveguides on the attenuation of the light in the waveguide is experimentally explored. The experiments are supported with numerical simulations of light propagation through both types of waveguides and outcoupling out of the straight waveguides. Furthermore, the effect of the size of the −1 defect terminations on the outcoupling efficiency is explored using simulations. Based on the presented design and manufacturing approach, liquid crystal optical waveguides of various shapes can be realized accurately with low-cost.

Ultraviolet-B Persistent Luminescence of CaF₂:Gd³⁺

After exposure to X-ray, CaF₂:Gd³⁺ continued to emit ultraviolet-B luminescence peaking at 313 nm, corresponding to the ⁶P_7/2 → ⁸S_7/2 transition of Gd³⁺. By X-ray photoelectron spectroscopy measurements, the valence variation model was excluded to explain the persistent luminescence of CaF₂:Gd³⁺. Potential applications including static labeling and dynamic tracking were demonstrated depending on such ultraviolet-B persistent luminescence. For further details, see article number 2401320 by Leipeng Li, Jianrong Qiu, Yanmin Yang, and co-workers from Hebei University and Zhejiang University.

The metamaterial Bragg grating is proposed for the experimental demonstration of Electromagnetically-Induced-Transparency (EIT) resonance with ultra-high Q = 5000 and contrast >20 dB. It is further applied to the demonstration of single frequency emission electrically injected DFB lasers in the near-infrared telecom domain. The ability of metamaterials to shape lasing properties with EIT-based low losses opens promising perspectives.

Abstract

The study shows that, in waveguide (WG) configuration, the coupling of a 2D plasmonic metamaterial grating (MMG) having a conventional Bragg period along the guide but a distinct period along the transverse axis can lead to Electromagnetically-Induced-Transparency (EIT) behavior. This epitomizes that metamaterials, as functional photonic building blocks, can lead to low losses in many standard devices if properly designed. The study reported the observation in passive WGs of a marked Fano-type EIT resonance with record high-quality factor: Q = 5000 and contrast >20 dB. Unlike any standard metal grating, MMG-assisted waveguides exhibit strong grating coupling strength and low-loss properties simultaneously. This concept is further applied to demonstrate single-frequency-emission electrically-injected Distributed Feedback (DFB) lasers in the near-infrared telecom domain. The key point is that laser emission occurs at the peak of EIT, i.e., the maximum in transmission. It therefore addresses one of the main critical issues of DFB lasers related to the single frequency yield. The laser performances are state-of-the-art (I_th < 20 mA, P_max > 20 mW at I  =  200 mA, SMSR > 50 dB, optical feedback tolerance >−21 dB compliant with IEEE 802.3 standard). The presented approach, compatible with existing industrial technologies, is promising for real-life telecom applications.

This study reports a CMOS-compatible and cost-efficient ultrathin Ni, as an alternative catalyst for metal-assisted chemical etching (MACE) of Si. Ultrathin Ni catalyzes local Si etching reactions, fabricating Si patterns uniformly on a single wafer. With an etching mechanism distinct from noble metal catalysts, Si is etched without strong oxidant under the influence of ultrathin Ni, simplifying the MACE process.

Abstract

Metal-assisted chemical etching (MACE), a wet-based anisotropic etching process for semiconductors, has emerged as an alternative to plasma-based etching. However, using noble metal catalysts in MACE limits the implementation of complementary metal-oxide-semiconductor (CMOS) processes. This study explores Si etching using an ultrathin Ni catalyst as a novel approach for MACE. The thickness of the Ni catalyst emerges as a critical parameter, with 1 nm of Ni proving to be the optimal thickness to achieve smooth and deep etching. Unlike conventional MACE methods, the ultrathin Ni catalyst enables Si etching without strong oxidants. Wafer-scale Si etching demonstrates the versatility of the ultrathin Ni catalyst in producing various microstructures. It is found that the ultrathin Ni/Si interfacial state plays a crucial role in influencing the Si reactivity, lowering the barrier for Si oxidation. CMOS-compatible and cost-efficient ultrathin Ni makes MACE a promising alternative for semiconductor nanofabrication. This study pioneers MACE using an ultrathin non-noble metal catalyst, offering valuable insights for researchers in this field.

Nature Communications, Published online: 02 November 2024; doi:10.1038/s41467-024-53907-w

van der Waals dielectric materials are required to promote the industrialization of miniaturized 2D electronics. Here, the authors report the growth of GdOCl single crystals with a dielectric constant of 15.3 and equivalent oxide thickness down to 1.3 nm, showing their application for the realization of high-performance 2D MoS2 transistors.

Transparent fluoroaluminate-phosphate glass ceramic scintillator with high crystallinity of (Ca, Sr, Ba)_1-xY_xF_2+x: Tb nanocrystals is designed, which exhibits strong radioluminescence characterized by a light yield 155% of BGO single crystal. Besides, the transparent glass ceramic scintillator can be applied as X-ray imaging application with a high spatial resolution of 23.4 lp mm⁻¹.

Abstract

Transparent glass-ceramic (GC) scintillator offers cost-effective and large-scale preparation for high-resolution X-ray imaging and detectors. However, it remains difficult to precipitate a high fraction of lanthanide activated fluoride nanocrystals that determine scintillation properties in glass. Herein, an ionic-covalent fluoroaluminate-phosphate glass network structure is constructed by combining simulation and experimental study, which enables the precipitation of (Ca, Sr, Ba)_1-xY_xF_2+x: Tb nanocrystals with high crystallinity (30.11%). By adjusting Tb doping concentration, heat treatment temperature and duration, a high internal quantum efficiency of 76.07%, the steady-state light yield of 12710 photons MeV⁻¹ and the lowest X-ray detection of 180 nGy_air s⁻¹ are obtained. Finally, a high-resolution (23.4 lp mm⁻¹) X-ray imaging application is realized by using the (Ca, Sr, Ba)_1-xY_xF_2+x: Tb GC scintillator. This provides a new option for the development of low-cost, high-performance scintillators for X-ray high-resolution imaging and low-dose detection applications.

Poly(dimethylsiloxane) (PDMS) is a promising polymer for optical waveguides, possessing a unique set of properties. This review provides a comprehensive overview of PDMS’ structure and properties, PDMS waveguide processing techniques, and its applications. By compiling established knowledge and new advancements, this review aims to elucidate PDMS’ potential and current limitations, paving the way for further advancements in PDMS waveguide technology.

Abstract

Poly(dimethylsiloxane) (PDMS) has emerged as a promising polymer for fabricating optical waveguides. Its optical transparency, stretchability, flexibility, biocompatibility, and facile processing are a complement to common optical materials that are more brittle and stiff such as fused silica, polystyrene (PS), and poly(methyl methacrylate) (PMMA). Although PDMS is not a new material, with its first synthesis dating back to the early twentieth century, recent decades have seen an increased effort to expand its use in optical waveguides beyond conventional rubber applications. This review compiles established concepts and new advancements in PDMS science to shed light on limitations and new opportunities to better harness PDMS’ potential for optical waveguiding. With the materials science tetrahedron in mind (structure, properties, processing, and performance), this review explores the state-of-the-art in PDMS waveguide technology and exposes relevant basic concepts pertaining to its physicochemical properties. The goal is to equip the photonics community with knowledge to further expand PDMS waveguide technology. The review covers three main topics: PDMS’ key properties (chemical, optical, thermal, and mechanical, besides biological and environmental aspects); PDMS waveguide fabrication techniques (processing, refractive index tuning, and post-processing); and its applications. The review concludes with a discussion of current challenges and future prospects.

Water-based silk nanopatterning by electron-beam lithography (EBL) based on post-exposure cross-linking allows for high precision 2.5D nanopatterning. This process is compatible with low-energy EBL and therefore the proximity effect is minimized. Using the proposed process, a security application is demonstrated. The post-exposure cross-linking way allows for delivering the information hidden in the silk resist with no disclosure risk.

Abstract

Nanopatterning on biomaterials has attracted significant attention as it can lead to the development of biomedical devices capable of performing diagnostic and therapeutic functions while being biocompatible. Among various nanopatterning techniques, electron-beam lithography (EBL) enables precise and versatile nanopatterning in desired shapes. Various biomaterials are successfully nanopatterned as bioresists by using EBL. However, the use of high-energy electron beams (e-beams) for high-resolutive patterning has incorporated functional materials and has caused adverse effects on biomaterials. Moreover, the scattering of electrons not absorbed by the bioresist leads to proximity effects, thus deteriorating pattern quality. Herein, EBL-based nanopatterning is reported by inducing molecular degradation of amorphous silk fibroin, followed by selectively inducing secondary structures. High-resolution EBL nanopatterning is achievable, even at low-energy e-beam (5 keV) and low doses, as it minimizes the proximity effect and enables precise 2.5D nanopatterning via grayscale lithography. Additionally, integrating nanophotonic structures into fluorescent material-containing silk allows for fluorescence amplification. Furthermore, this post-exposure cross-linking way indicates that the silk bioresist can maintain nanopatterned information stored in silk molecules in the amorphous state, utilizing for the secure storage of nanopatterned information as a security patch. Based on the fabrication technique, versatile biomaterial-based nanodevices for biomedical applications can be envisioned.

With the uniquely-designed one-pot method and space-confined process, the controlled growth of a series of 2D-3D perovskite lateral heterostructures is achieved. Based on the tunable dual-band optical response characteristics, a wavelength-tunable light communication system based on the lateral heterostructure is realized. This work provides a convenient and reliable approach for the direct growth of mixed-dimensional halide perovskite heterostructures, further demonstrating their potential in high-performance detecting and dual-band sensing fields.

Abstract

Lateral heterostructures based on halide perovskites exhibit great potential in the advancement of next-generation optoelectronic devices. Among them, mixed dimensional perovskite heterostructures, particularly 2D-3D ones, offer promising opportunities for semiconductor integration and device miniaturization by combining the advantages of 2D and 3D perovskites. However, the controllable and rapid growth of 2D-3D halide perovskite lateral heterostructures has not yet been achieved. This study presents an efficient strategy that integrates one-pot method and space-confined process to enable liquid-phase lateral growth of a series of 2D Ruddlesden-Popper (RP) perovskites on the sides of 3D perovskites. The photodetectors (PDs) based on (BA)₂MA_n-1Pb_nBr_3n+1-MAPbBr₃ (n = 1, 2, 3) lateral heterostructures demonstrate outstanding optoelectronic performance, featuring an on/off ratio of up to 1.4 × 10⁴, a high responsivity of 4.4 A W⁻¹ and a detectivity of 3.9 × 10¹³ Jones at 425 nm, 3 V bias. In addition, by combining the tunable dual-band photoresponse characteristic with the dual-beam irradiation modes, a wavelength-tunable light communication system based on the lateral heterostructure PDs is realized. This work provides a convenient and reliable approach for the direct growth of mixed-dimensional halide perovskite heterostructures, further demonstrating their potential in high-performance detecting and dual-band sensing fields.

The product of CVD-synthesized inorganic lead-free CsAg₂I₃ single crystals with high quality and phase-pure characteristics enables to achieve ultra-fast polarization-sensitive UV photodetectors. This research advances this functional material toward a robust optoelectronic device, thereby exploring new traits and opening up multifunctional applications.

Abstract

Low-dimensional ternary silver halide (CsAg₂I₃), an emerging inorganic lead-free perovskite, has garnered significant scientific attention due to its strong quantum confinement effects, wide bandgaps, non-toxicity, and others. However, the photophysical properties and optoelectronic performance of CsAg₂I₃ materials and devices are significantly compromised by crystal quality and defects arising from liquid-phase preparation. Herein, 1D CsAg₂I₃ single crystals newly grown by the chemical vapor deposition method are reported. These crystals display exceptional quality and stability over a 3-month period despite exposure to air and moisture. The high in-plane anisotropic structure, phonon vibrations, and refractive index of CsAg₂I₃ crystals are also experimentally elucidated. Polarization-sensitive ultraviolet photodetector based on the CsAg₂I₃ monocrystal features a responsivity of 139  mA W⁻¹, a specific detectivity of 1.05 × 10¹¹ cm Hz^1/2 W⁻¹, an ultra-fast photoresponse speed of 48.2/69.1 µs, and a dichroic ratio of 2.66 upon 360 nm irradiation at −5.0 V bias. The photodetector excels amongst its competitors, moving toward the potential application of rapid optical anti-counterfeiting identification. This work, which leverages grown high-crystalline and highly stable CsAg₂I₃ monocrystals, holds promises for advancing this functional material into a robust next-generation optoelectronic devices capable of probing sensitive optical sensing and specific azimuth recognition.

Glial scarring (GS) occurs due to the activation of astrocytes in response to a physical insult to the brain, such as the insertion of a neural implant. Here, a biophysical paradigm for inhibiting and reversing GS using stochastic nanoroughness via Piezo-1 signaling is demonstrated thus, opening up a novel approach for engineering a neural biomaterial interface for the CNS.

Abstract

Physical insult to the central nervous system (CNS) such as during electrode insertion leads to reactive astrogliosis which in turn contributes to glial scarring (GS). To date, reducing GS in these settings has focused on pharmacological agents and variations in electrode material composition or implantation procedures, and the role of electrode surface topography has remained unexplored. Since proteoglycans, a major component of GS tissue, possesses very well-defined (nano) topography, a role for stochastic nanoroughness in glial scar formation is theorized. Using an in vitro system, we provide proof of concept that on substrates possessing stochastic nanoroughness corresponding to that of healthy astrocytes, glial scar formation is significantly inhibited, and more importantly, can be even reversed, and it involves signaling via the stretch-activated cation channel Piezo-1. In vivo studies reveal an absence of astrocytes aggregation along the electrode track of chronically implanted electrodes modified with stochastic surface nanoroughness, compared to non-modified electrodes, while signal detection within the superior colliculus remains unaffected. These findings shedlight on the crucial role of stochastic biophysical cues in modulating GS formation; and offer a promising non-chemical approach for engineering neural biomaterials interface for the CNS.

Nature Materials, Published online: 28 October 2024; doi:10.1038/s41563-024-02027-3

Tissue monolayers avoid rupture at large tensile stresses through a strain-stiffening process governed by intermediate keratin filaments.

Spintronics applications in two-dimensional (2D) magnetic materials can significantly contribute to the miniaturization and energy efficiency of semiconductor devices. However, current 2D ferromagnetic materials face challenges such as ferromagnetic instability and low Curie temperature (Tc), which limit their broader application. In this study, 2D room-temperature ferromagnetic LaAlO3 was successfully prepared with supercritical carbon dioxide (SC CO2). With the enhanced stress effect of CO2 molecules, the contents of oxygen vacancies OV, aluminium vacancies AlV, and AlO4 in the 2D structure are elevated, and then the ferromagnetic properties of LaAlO3 appeared to be significantly enhanced due to defects and spatial symmetry breaking of the octahedron. Notably, the 2D intrinsic ferromagnetic LaAlO3 exhibited a Tc above 350 K. Therefore, this work supplies a new means for SC CO2 to modulate the microstructure and ferromagnetic properties of 2D LaAlO3, which is conducive to expanding the applications of LaAlO3.

Sulfur and Nitrogen-doped graphene quantum dotes (GQDs) decrease the viability in a dose-dependent way, and exert little activation on human THP-1 immune cells. These doped GQDs enter easily into the cytoplasm of THP-1 macrophages. The diminution of fluorescence signals, the loss of structure and crystal lattice provide evidence of the biodegradability of both GQDs. This study ensures the potential of this type of carbon materials for biomedical applications.

Abstract

Graphene quantum dots (GQDs), small graphene domains with lateral dimensions lower than 10 nm, are increasingly used in electronics, composites, and biomedicine. Chemical doping of GQDs allows tuning their optical properties. Immune cells are among the first cells exposed to nanomaterials entering a living body, rapidly triggering a downstream immune response. However, the assessment of the impact of chemically-doped GQDs on the immune system remains rather limited if not absent. In this context, the effects and the biodegradability of sulfur-doped and nitrogen-doped GQDs (S-GQDs and N-GQDs) on human monocytes and macrophages are evaluated. The metabolic activity, membrane integrity, apoptosis, and intracellular reactive oxygen species (ROS) generation are studied. In parallel, the degradation of GQDs using human myeloperoxidase and a peroxynitrite-mediated system is investigated in test tube. Their degradation in macrophages is also pursued. High-resolution transmission electron microscopy (HRTEM), fluorescence spectroscopy, Raman, and flow cytometry are used to confirm the degradation. Overall, both GQDs exert little activation on monocytes and macrophages although they decrease the metabolic viability in a dose-dependent manner. The loss of native GQD structure and crystal lattice provide evidence of their biodegradability. Both the safety and biodegradability of S-GQDs and N-GQDs ensure their potential in biomedical applications.

Cell-surface-associated materials (e.g., nanoparticles, microparticles, and polymeric coatings) can prevent cell damage or loss, control cell transport and biodistribution, mask cell-surface antigens, regulate cell phenotypes, and deliver therapeutic agents to target tissues.

Abstract

Cell therapies are emerging as a promising new therapeutic modality in medicine, generating effective treatments for previously incurable diseases. Clinical success of cell therapies has energized the field of cellular engineering, spurring further exploration of novel approaches to improve their therapeutic performance. Engineering of cell surfaces using natural and synthetic materials has emerged as a valuable tool in this endeavor. This review summarizes recent advances in the development of technologies for decorating cell surfaces with various materials including nanoparticles, microparticles, and polymeric coatings, focusing on the ways in which surface decorations enhance carrier cells and therapeutic effects. Key benefits of surface-modified cells include protecting the carrier cell, reducing particle clearance, enhancing cell trafficking, masking cell-surface antigens, modulating inflammatory phenotype of carrier cells, and delivering therapeutic agents to target tissues. While most of these technologies are still in the proof-of-concept stage, the promising therapeutic efficacy of these constructs from in vitro and in vivo preclinical studies has laid a strong foundation for eventual clinical translation. Cell surface engineering with materials can imbue a diverse range of advantages for cell therapy, creating opportunities for innovative functionalities, for improved therapeutic efficacy, and transforming the fundamental and translational landscape of cell therapies.

IoT is growing rapidly through the convergence of artificial intelligence, and force sensors are essential for 3D space applications. Conventional TENG-based force sensors suffer accuracy issues depending on contact materials. By introducing the Scott–Russell linkage, SRI-TENG separates signal generation and measurement, improving accuracy. Lubricant enhances durability, enabling stable measurements for 270 000 cycles. Also, utilizing deep learning SRI-TENG can recognize tactile properties.

Abstract

The rapid growth of Internet of Things (IoT) in recent years has increased demand for various sensors to collect a wide range of data. Among various sensors, the demand for force sensors that can recognize physical phenomena in 3D space has notably increased. Recent research has focused on developing energy harvesting methods for sensors to address their maintenance problems. Triboelectric nanogenerator (TENG) based force sensors are a promising solution for converting external motion into electrical signals. However, conventional TENG-based force sensors that use the signal peak can negatively affect data accuracy. In this study, a Scott–Russell linkage-inspired TENG (SRI-TENG) is developed. The SRI-TENG has completely separate signal generation and measurement sections, and the number of peaks in the electrical output is measured to prevent disturbing output signals. In addition, the lubricant liquid enhances durability, enabling stable force signal measurements for 270 000 cycles. The SRI system demonstrates consistent peak counts and high accuracy across different contacting surfaces, indicating that it can function as a contact material-independent self-powered force sensor. Furthermore, using a deep learning method, it is demonstrated that it can function as a multimodal sensor by realizing the tactile properties of various materials.

Printing interference colors entails complex procedures and large-scale printing systems for the scarcity of inks that exhibit both sensitivity and tunability to external fields. This work invents a type of paramagnetic ink with record-level magneto-optical sensitivity based on 2D materials. These inks exhibit polychrome in one magnetic field, paving the way for preparing transmissive interference colors in an energy-saving and damage-free manner.

Abstract

Interference colors hold significant importance in optics and arts. Current methods for printing interference colors entail complex procedures and large-scale printing systems for the scarcity of inks that exhibit both sensitivity and tunability to external fields. The production of highly transparent inks capable of rendering transmissive colors has presented ongoing challenges. Here, a type of paramagnetic ink based on 2D materials that exhibit polychrome in one magnetic field is invented. By precisely manipulating the doping ratio of magnetic elements within titanate nanosheets, the magneto-optical sensitivity named Cotton–Mouton coefficient is engineerable from 728 to a record high value of 3272 m⁻¹ T⁻², with negligible influence on its intrinsic wide optical bandgap. Combined with the sensitive and controllable magneto-responsiveness of the ink, modulate and non-invasively print transmissive interference colors using small permanent magnets are precised. This work paves the way for preparing transmissive interference colors in an energy-saving and damage-free manner, which can expand its use in widespread areas.

Nature Photonics, Published online: 23 October 2024; doi:10.1038/s41566-024-01549-1

Researchers demonstrate optical weights for in-memory photonic computing using magneto-optic memory cells comprising Ce:YIG on silicon micro-ring resonators. Non-reciprocal phase shift provides a fast, efficient and robust integrated optical processing platform.

A novel quantum PUF concept is proposed and demonstrated by multidimensional fingerprint features of single photon emitters from randomly distributed pyramidal AlN nanocrystals on Si. The work explores a new application direction for quantum emitters and provides an advanced hardware security solution at the sub-nanoscale for the information security in the post-quantum age.

Abstract

Physical unclonable function (PUF) has emerged as a unique physical'fingerprint' that is inherently difficult to replicate. It shows tremendous application value in various hardware security areas such as identity authentication, chip anticounterfeiting, communication encryption, blockchain, etc. However, with the rapid development of 3D nanoprinting, classical PUFs constructed with disordered micro-nanostructures face tremendous threats from physical cloning attacks. Herein, this study proposes and demonstrates the utilization of room-temperature single-photon emitters derived from atomic defects in randomly distributed pyramidal aluminum nitride (AlN) nanocrystals as a novel quantum PUF to resist physical cloning attacks. The fabrication of this quantum PUF on silicon (Si) wafers enables seamless integration with silicon photonic integrated circuits. The multidimensional fingerprint features of the single-photon emitters are highly sensitive to the lattice parameters of the uneven AlN nanocrystals. Furthermore, each single photon emitter can work as a quantum random number generator to ensure the fundamental unpredictability of PUFs. The subatomic precision requirement coupled with unpredictable quantum emission behavior makes it practically impossible to attack the proposed quantum PUF, providing a promising solution for information security in the post-quantum era.

Nature Materials, Published online: 30 September 2024; doi:10.1038/s41563-024-01988-9

Precise stress control of thin films enables damage-free dry transfer printing onto flexible substrates.