Device Applications Research Articles

A comprehensive review of yttrium aluminum nitride: crystal structure, growth techniques, properties, and applications

YAlN has emerged as a wide band gap semiconductor with high potential to compete with ScAlN in industrial applications. Theoretical predictions about YAlN’s material properties have been the main motivation for conducting experimental investigations and verify simulated results. However, several challenges have been faced in experimental studies on YAlN that contradict theoretical data, especially when trying to reach higher alloy concentrations. This work presents a systematic review analyzing different material properties including structural characterization, elastic properties, and thermal features. It combines all available experimental data on the growth and reported material parameters, such as band gap, lattice parameters, and electrical properties with the aim of introducing a new motivation to further study YAlN’s potential in various fields of device applications. The review provides a comprehensive overview on the current state of knowledge on YAlN, highlighting the discrepancies between theoretical predictions and experimental results. By providing information from multiple studies, this work offers valuable insights into the challenges and opportunities associated with YAlN development, paving the way for future research directions and potential industrial applications of this promising wide band gap semiconductor.

Crystal structure modulating performances for 213-nm GeO2 solar-blind photodetectors via DC reactive magnetron sputtering method

Owing to the ultra-wide bandgap energy, high thermal conductivity, and ambipolar capability, GeO2 films are receiving great attention for potential applications in power devices and solar-blind photodetectors. However, the precise control of the crystal structure and optical property is a huge challenge due to close free formation energies of multiple phases, inhibiting the GeO2 based practical device applications. Here, we have fabricated quartz and rutile-GeO2 thin films utilizing the magnetron sputtering based synthetic strategy, which exhibit ultra-wide bandgap energies of 5.51 and 5.88 eV. On the foundation of these ultra-wide bandgap semiconductors, obvious photoresponse characteristics have been achieved at 213 nm and the quartz-GeO2 device exhibits better performances including a short fall time of 148.5 ms, a high photo-dark current ratio of 86.65, large photoresponsivity of 4.56 A/W, and high detectivity of 6.78 × 1013 Jones, which can be attributed to the less oxygen defect exists in the quartz-GeO2 film due to the oxygen-rich growth condition and the better lattice matching with sapphire. Our findings suggest that the GeO2 thin film is a candidate material for optoelectronic device applications and will provide a facile and innovative strategy to develop the solar-blind photodetector.

Fabrication of Graphene Polyhedra: Unveiling New Structures, Forms, and Properties

AbstractA hybrid nanoporous carbon alloy material is synthesized using a core–shell structure based on metal–organic frameworks, revealing a novel graphene polyhedral form. The presence of carbon and metal as doped cobalt carbides based on morphed graphene within the graphene polyhedra is confirmed through a combination of X‐ray diffraction, X‐ray photoelectron spectroscopy, transmission electron microscopy, and Raman spectroscopy analyses. These novel graphene polyhedra exhibit magnetoelectric coupling properties at room temperature. The magnetic state control is verified using a magnetic probe; the changes in the magnetic state increased with a higher applied bias, and the poling direction of the magnetic phase is reversed based on the scanning direction of the probe. This discovery holds promise for future applications in ultrafast devices and carbon‐based spintronics research.

Extendable Synthesis of Organic Cations for In Situ Construction of Hybrid Metal Halideswith Near-Unity Photoluminescenceand Strong Second Harmonic Generation.

The A-site organic components of organic-inorganic hybrid metal halides (OIHMHs) significantly impact their crystal structure and optoelectronic properties. However, chemical modification of A-site cations has been mostly limited to commercial organic precursors, which restricts thestructural variability of OIHMHs for optimal functionalities. Herein we have proposed an extendable synthesis approach to the direct procurability of various organic cations with desireable structures for the in situ construction of a library of OIHMH materials. The template condensation reaction between dimethyl sulfoxide and acetone derivatives yields A-site organic cations with exquisite control of modularization and regioselectivity within the OIHMH crystallization system. The as-fabricated OIHMHs demonstrated highly efficient linear optical photoluminescence or nonlinear optical second harmonic generation,promising potential applications in photonic devices. This in situ synthetic strategy offers a structural extension of OIHMHs and establishes afundamental methodological platform for screening functional OIHMH materials.

Extendable Synthesis of Organic Cations for In Situ Construction of Hybrid Metal Halides with Near‐Unity Photoluminescence and Strong Second Harmonic Generation

The A‐site organic components of organic‐inorganic hybrid metal halides (OIHMHs) significantly impact their crystal structure and optoelectronic properties. However, chemical modification of A‐site cations has been mostly limited to commercial organic precursors, which restricts the structural variability of OIHMHs for optimal functionalities. Herein we have proposed an extendable synthesis approach to the direct procurability of various organic cations with desireable structures for the in situ construction of a library of OIHMH materials. The template condensation reaction between dimethyl sulfoxide and acetone derivatives yields A‐site organic cations with exquisite control of modularization and regioselectivity within the OIHMH crystallization system. The as‐fabricated OIHMHs demonstrated highly efficient linear optical photoluminescence or nonlinear optical second harmonic generation, promising potential applications in photonic devices. This in situ synthetic strategy offers a structural extension of OIHMHs and establishes a fundamental methodological platform for screening functional OIHMH materials.

Multi-parameter control of photodetection in van der Waals magnet CrSBr

Photodetectors equipped with multi-parameter control hold the potential to deliver exceptional performance in a wide range of scenarios, paving the way for developing novel spin-opto-electronic devices. Nevertheless, the integration of such capabilities within a single device is challenging due to the necessity of harmonizing multiple materials with varying degrees of freedom. In this study, we introduce the van der Waals magnet CrSBr, featuring inherent anisotropy and distinctive spin-electronic coupling, to this realm. The linear dichroic ratio of the photocurrent in CrSBr tunneling device can reach ~60 at 1.65 K, and the photoresponse experiences a significant boost with increasing magnetic field. Additionally, the unique spin-charge coupling engenders a photon energy-dependent photocurrent that is modulated by an external field and is validated by first-principle calculations. Our findings elucidate the effective multi-parameter control of photodetection based on vdWs magnet CrSBr, highlighting its potential applications in cutting-edge optoelectronic devices and as a highly sensitive probe medium.

Sodium Carboxymethylcellulose/Polydopamine Biocellulose Coatings with Enhanced Wet Stability for Implantable Medical Devices.

Sodium carboxymethylcellulose (CMC) is a biocompatible and biodegradable derivative of cellulose, making it a promising material for biomedical applications. However, its poor stability in aqueous environments has significantly limited its use in long-term biomedical devices. Here, we present for the first time a simple and controllable method to enhance the wet stability of CMC coatings by cross-linking of CMC and polydopamine (PDA) and self-polymerization of PDA for widespread applications in biomedical devices. A series of CMC/PDA coatings were fabricated on the initial PDA layers by using dip coating and subsequently heated at 200 °C. The performance of the CMC/PDA coatings and their chemical and structural stability in aqueous media have been systematically analyzed, and the mechanisms underpinning their robust performance have been revealed. FITR, X-ray photoelectron spectroscopy (XPS), and gel permeation chromatography (GPC) results showed that CMC/PDA coatings involved amidation and esterification reactions as well as self-polymerization of PDA. Degradation studies in phosphate-buffered saline (PBS) solution at 37 °C indicated degradation via ester and amide bond cleavage, with the stability of CMC/PDA coatings surpassing that of individual PDA and CMC coatings over a 30-day immersion period. The CMC/PDA coating with a CMC concentration of 15 mg/mL exhibited the highest adhesion strength in an aqueous environment, which was attributed to the high cross-linking of CMC and PDA, as well as the intrinsic stability of PDA. The CMC/PDA coatings demonstrated favorable viability, growth, and proliferation of endothelial cells. The stable and biocompatible biocellulose coatings can be easily applied from aqueous solutions onto almost any type of solid metal and ceramic material, providing a promising dimension for surface engineering of vascular scaffolds and tissue engineering constructs.

Dual‐Band Metasurface‐Based Structured Light Generations for Futuristic Communication Applications

Structured beams carrying orbital angular momentum carry significant potential for various applications, including optical trapping, manipulations, communications, microscopy, and so on. Among these, perfect vortex (PV) beams are highly attractive due to their immunity to topological charge variations and nondiffracting properties. However, conventional PV beam generation methods typically operate at a single wavelength and rely on bulky components, complicating photonic device integration. To address this, a single‐cell‐driven, dual‐band metasurface platform is experimentally demonstrated to generate nondiffracting PV beams spanning from UV to visible wavelengths (261–405 nm). The proposed metasurfaces, made of rectangular‐shaped silicon nitride nanoantennas, achieve an average transmission efficiency of 65% across dual spectrums. Simulated and experimental results show that the metasurfaces maintain topological charge‐insensitive ring radii. The findings highlight a novel approach for PV beam generations, which can lead to new categories of ultrathin optical devices for diverse applications, including wireless communication, particle trapping, and biomedical imaging.

Critical review on the derivative of graphene with binary metal oxide-based nanocomposites for high-performance supercapacitor electrodes

Abstract Supercapacitors, owing to their high power density and rapid charge–discharge capabilities, have gained significant attention as energy storage devices in various applications. In the context of electrochemical supercapacitors, this article provides a comprehensive review of the production and electrochemical performance of binary metal oxide (BMO) and reduced graphene oxide (rGO) composite materials. The synthesis processes and synergistic benefits of BMO–rGO composites, with an emphasis on how they perform better than separate parts in terms of specific capacitance and cycle stability, are discussed. The potential of BMO–rGO composites as high-performance electrode materials for supercapacitors is highlighted in this research. In the context of electrochemical supercapacitors, this work provides a comprehensive review of the production and electrochemical performance of binary transition metal oxide (TMO) and rGO composite materials. Composite materials with enhanced electrochemical characteristics that are appropriate for supercapacitor applications are the primary novelty, which is the synergistic combination of rGO with a variety of TMOs. Compared to individual TMOs or other carbonaceous materials, these composites demonstrate enhanced specific capacitance, energy density, power density, cyclic stability, and rate capability. The synthesis processes and synergistic benefits of BMO–rGO composites are discussed, with an emphasis on their superior performance in specific capacitance and cycle stability compared to individual components. This research highlights the potential of BMO–rGO composites as high-performance electrode materials for supercapacitors, showcasing their enhanced specific capacitance, improved charge storage capacity, increased power density, excellent cycling stability, and overall durability even after numerous charge–discharge cycles.

Precise Tailoring of Unprecedent Layered Perovskite‐Type Heterostructure Ferroelectric via Chemical Molecular Scissor

AbstractPrecise stacking of distinct two‐dimensional (2D) rigid slabs to build heterostructures has renewed the portfolio of 2D materials, e.g., magic‐angle graphene, due to the emergence of exotic physical properties. Recently, single‐crystal heterostructures of layered perovskites have emerged as an exciting branch, while it remains scarce to achieve strong ferroelectricity in this new heterostructure family. Here, we present the first ferroelectric of 2D perovskite heterostructures as single crystal, (EA3Pb2Br7)EA4Pb3Br10 (1, EA=ethylamine), by precisely tailoring inorganic sheets via a chemical molecular scissor. It has notable ferroelectricity of large spontaneous polarization (Ps~5.0 μC/cm2) and high Curie temperature (Tc~375 K). Structurally, its inorganic framework adopts a unique 2D heterostructure that contains two different rigid slabs of {EA3Pb2Br7}n and {EA4Pb3Br10}n. This motif is self‐assembled by layer‐by‐layer clipping of rigid prototype sheets, using extra neopentylamine as a molecular chemical scissor. Unlike epitaxial growth, such a molecule‐level stacking facilitates the growth of heterostructure single crystals. Combining its strong ferroelectricity and inherent anisotropy, crystal‐based device of 1 exhibits an ultrahigh polarized‐light sensitivity up to ~37 in self‐powered mode, being the highest level of 2D perovskite ferroelectric family. Our work will facilitate the further development of ferroelectric materials for optoelectronic device applications.

Precise Tailoring of Unprecedent Layered Perovskite-Type Heterostructure Ferroelectric via Chemical Molecular Scissor.

Precise stacking of distinct two-dimensional (2D) rigid slabs to build heterostructures has renewed the portfolio of 2D materials, e.g., magic-angle graphene, due to the emergence of exotic physical properties. Recently, single-crystal heterostructures of layered perovskites have emerged as an exciting branch, while it remains scarce to achieve strong ferroelectricity in this new heterostructure family. Here, we present the first ferroelectric of 2D perovskite heterostructures as single crystal, (EA3Pb2Br7)EA4Pb3Br10 (1, EA=ethylamine), by precisely tailoring inorganic sheets via a chemical molecular scissor. It has notable ferroelectricity of large spontaneous polarization (Ps~5.0 μC/cm2) and high Curie temperature (Tc~375 K). Structurally, its inorganic framework adopts a unique 2D heterostructure that contains two different rigid slabs of {EA3Pb2Br7}n and {EA4Pb3Br10}n. This motif is self-assembled by layer-by-layer clipping of rigid prototype sheets, using extra neopentylamine as a molecular chemical scissor. Unlike epitaxial growth, such a molecule-level stacking facilitates the growth of heterostructure single crystals. Combining its strong ferroelectricity and inherent anisotropy, crystal-based device of 1 exhibits an ultrahigh polarized-light sensitivity up to ~37 in self-powered mode, being the highest level of 2D perovskite ferroelectric family. Our work will facilitate the further development of ferroelectric materials for optoelectronic device applications.

Antisymmetric Magnetoresistance in a CrTe2/Bi2Te3/CrTe2 van der Waals Heterostructure Grown by MBE.

The magnetoresistance (MR) of spin valves usually displays a symmetric dependence on the magnetic field. An antisymmetric MR phenomenon has been discovered recently that breaks field symmetry and has the potential to realize polymorphic memory. In this work, centimeter-size and high-quality CrTe2/Bi2Te3/CrTe2 van der Waals (vdWs) heterostructure devices have been prepared using molecular beam epitaxy (MBE). By changing the magnetization direction of the top and bottom layers of CrTe2, an antisymmetric MR effect with high, intermediate, and low resistance states has been found and persists up to 75K. The emergence of this antisymmetric MR phenomenon is attributed to the spin Hall effect, which generates spin currents with both spin-up and spin-down orientations on the upper and lower surfaces of Bi2Te3. The spin currents diffuse or reflect at the Bi2Te3/CrTe2 interfaces alongside the additional charge currents induced by the inverse spin Hall effect (ISHE). Through theoretical calculations, the existence of the antisymmetric MR effect has also been confirmed. Our work emphasizes the use of the MBE technology to grow vdWs heterostructures to explore new physical phenomena and potential applications of spin electronic devices in polymorphic solid-state storage.

A Soft Robotic Textile‐Actuated Anthropomorphic Artificial Shoulder Mechanism

Replicating the human shoulder in anthropomorphic systems is notoriously challenging due to its complex combination of mobility and strength. This study presents the design, fabrication, and control of a new soft artificial shoulder that achieves a broad range of motion, torque, and compliance. Powered by soft robotic textiles consisting of a network of hydraulic artificial muscles, the engineered shoulder effectively mimics intricate shoulder movements, including flexion/extension, abduction/adduction, and medial/lateral rotation. Experiments demonstrate that the artificial shoulder can generate a peak torque of 9.6 ± 0.1 Nm, covering 65.3% of the human shoulder workspace. The artificial shoulder capability is demonstrated through several experimental testbeds. First, it is employed to develop a gesture‐controlled telemanipulation robotic system, applicable to robot‐assisted surgery, hazardous environment operations, gaming, and rehabilitation. Second, it serves as a platform for simulating and studying neurological disorders, such as Parkinson's disease. This approach offers a reliable in vitro testing ground for wearable device validation, providing a crucial intermediary step before progressing to user studies. The artificial shoulder marks a significant advancement in next‐generation anthropomorphic systems, closely mimicking the human musculoskeletal system, with promising applications in wearable assistive devices, haptics, orthopedic testing, and medical technologies.

DTXG-RF-based Intrusion Detection System for Artificial IoT Cyber Attacks

The swift advancement of networking technology and the rising incidence of cyber-attacks have made effective cybersecurity a critical priority. The primary concern with IoT networks is their susceptibility to vulnerabilities. IoT security necessitates the substantial involvement of artificial intelligence as a security technology to mitigate these challenges. Cyberattacks are evolving in sophistication, consequently posing greater obstacles in the precise detection of intrusions. An Intrusion Detection System (IDS) is a device or software application that monitors the activities of network systems for malicious actions or policy breaches and produces reports. The primary objective of an IDS is to efficiently identify attacks. Moreover, it is imperative to identify attacks at an early stage to mitigate their effects. Machine learning models have become increasingly popular in IDSs due to their capacity to process substantial data volumes and identify patterns in real time. Machine learning involves building an algorithm to identify consistent patterns within a dataset. This study aimed to build an IDS using an ensemble machine learning (DTXG-RF) model and compare it with DT, XGBoost, KNN, RF, NB, and CatBoost on the CIC-IoT-2023 and a Ransomware dataset. The results showed that the proposed DTXG-RF outperformed other machine learning models with accuracy reaching 95.06%.

Influence of Alkyl Chain Length and Bromine Substitution on Thermal, Photophysical, and Optical Properties of Biphenyl Luminescent Molecules

This study investigates a series of bromine-substituted alkoxy biphenyl derivatives to explore their potential as luminescent and optical materials for applications in display technologies, sensors, and photonic devices. Four compounds were synthesized, including 5-Br, 6-Br, 7-Br, and a comparative non-halogenated molecule 6-H. The findings reveal that the bromine-substituted derivatives exhibit enhanced thermal stability as the alkoxy chain length increases, though none of the compounds displayed liquid crystalline phases, likely due to molecular flexibility and steric hindrance from the bromine atoms. Photophysical studies showed that the compounds exhibit tunable emission colors ranging from green to blue, depending on the side chain length and the presence or absence of bromine. Importantly, the introduction of bromine was found to enhance the photophysical properties, including increased quantum yields and longer emission lifetimes, compared to the non-halogenated analog. Moreover, these luminescent molecules can maintain strong fluorescence both in solution and when forming aggregates. Furthermore, the optical properties, such as dielectric constant, extinction coefficient, refractive index, and optical conductivity, were thoroughly examined. The results indicate that structural variations, including alkyl chain length and bromine substitution, significantly influence the capability of these materials to store and dissipate electrical energy. Their strong optical responses, high energy storage capabilities, and sensitivity to structural modifications suggest that the studied materials have substantial potential for applications in energy storage, sensing, optoelectronics, and non-linear optics. These findings offer important guidelines for the rational design of multifunctional luminescent and optical materials, representing a significant step forward in the development of practical applications of smart materials and advanced photonic devices.

Enhancing mechanical and thermal properties of bio-composites: Synergistic integration of ZnO nanofillers and nanocrystalline cellulose into durian seed starch matrix.

The increasing demand for sustainable materials necessitates advancements in bio-composites with enhanced properties. This study addresses the limitations of Durio zibethinus Murr (DZM) seed starch bio-composites, particularly their poor mechanical strength and thermal stability. Using solution casting, zinc oxide (ZnO) nanofillers and nanocrystalline cellulose (NCC) were incorporated into the starch matrix. The optimized composite with 0.4g ZnO exhibited a significant improvement in crystallinity (79.40%), tensile strength (0.44MPa), and thermal stability (15.54% residual mass). These findings highlight the potential of the developed bio-nanocomposites for applications in food packaging and medical devices, combining enhanced durability with environmental sustainability.

A review of machine learning applications in hydrogen electrochemical devices

A review of machine learning applications in hydrogen electrochemical devices

A wearable electrochemical sensor utilizing multifunctional hydrogel for antifouling ascorbic acid quantification in sweat.

The accurate and reliable quantification of the levels of disease markers in human sweat is of significance for health monitoring through wearable sensing technology, but the sensors performed in real sweat always suffer from biofouling that cause performance degradation or even malfunction. We herein developed a wearable antifouling electrochemical sensor based on a novel multifunctional hydrogel for the detection of targets in sweat. The integration of polyethylene glycol (PEG) into the sulfobetaine methacrylate (SBMA) hydrogel results in a robust network structure characterized by abundant hydrophilic groups on its surface, significantly enhancing the PEG-SBMA hydrogel's antifouling and mechanical properties. The wearable sweat sensor is specifically designed for ascorbic acid (AA) detection. The incorporation of a silver nanoparticles-molybdenum disulfide (AgNPs-MoS2) composite material into the hydrogel significantly enhances its catalytic properties towards AA. Electrochemical analysis confirms that the sensor reliably detects AA in real sweat with minimal interference from other components and bacteria, demonstrating its practical application potential. Furthermore, this multifunctional hydrogel's mechanical robustness and strong adhesion to various substrates ensure its practical applicability in wearable devices. This technology provides a foundation for accurate health monitoring in wearable sensors, enabling advanced, non-invasive diagnostic tools for personalized healthcare.

Deciphering the role of CIELab on emission mechanism of Samarium (Sm3+) ions embedded boro-tellurite glasses for applications in optoelectronics devices

Deciphering the role of CIELab on emission mechanism of Samarium (Sm3+) ions embedded boro-tellurite glasses for applications in optoelectronics devices

Nanometer thick iron garnet films with high Faraday rotation

Here we demonstrate nanometer thick iron garnet films with high specific Faraday rotation suitable for the magneto-optical applications. Bismuth-substituted iron garnet films of compositions Bi1Y2Fe5O12 and Bi1Tm2Fe5O12 deposited on gadolinium gallium garnet substrate are fabricated and characterized. Their thicknesses range from 2 to 10 nm, which corresponds to just a few crystal lattice constants. Spectacularly, Faraday rotation of the 2 nm thick Bi1Y2Fe5O12 film reaches 29.3deg/µm at 420 nm that is comparable to the single crystal micrometer thick films of similar composition. The film surface morphology by atomic force microscopy gives root mean square (RMS) roughness of the nanometer thick films as small as 0.13 nm that is also similar to the RMS of single crystal micrometer thick films. Moreover, the 3 nm thick Bi1Tm2Fe5O12 films demonstrate a pronounced effective uniaxial anisotropy. These all make the fabricated nanometer thick films very promising for their potential applications in magneto-optical devices and quantum technologies.