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Synergistic Ti doping and carbon-coating to modulate Na+ migration channels in Na2FeP2O7 cathode for fast sodium storage
Phosphate salt Na2FeP2O7 has emerged as a potential candidate material for sodium-ion batteries due to its high stability in the triclinic structure and low cost. However, its practical implementation is hindered by intrinsic limitations such as poor electronic conductivity and sluggish Na+ diffusion kinetics. In this study, Ti-doped Na2FeP2O7 composite coated with an in situ formed amorphous carbon layer (0.1Ti-NFO@C) was synthesized via a sol-gel method followed by high-temperature calcination. The introduced Fe/Ti–O bonding network and carbon coating synergistically enhance the electronic conductivity and Na+ transport kinetics, which significantly improve the rate performance and specific capacity. The resulting 0.1Ti-NFO@C delivers a reversible capacity of 109.67 mAh g−1 at 0.2C, and retains a capacity of 77.90 mAh g−1 even at a high current density of 10C. Furthermore, when assembled into a full cell with hard carbon, it exhibits an initial discharge capacity of 110.04 mAh g−1 at 0.5C and retains a capacity of 54.88 mAh g−1 after 200 cycles at 2.0C, with a Coulombic efficiency exceeding 99%. These structural modifications significantly enhance the material's performance, providing valuable insights toward the practical implementation of polyanion cathodes.
Periodically tunable continuous-wave intracavity diamond Raman laser via birefringent filter
We report a periodically tunable continuous-wave intracavity diamond Raman laser employing a rotating quartz birefringent filter (BRF). Experimental results reveal a counter-intuitive phenomenon where the insertion of a lossy BRF leads to higher Stokes output power compared to the free-running regime. This power enhancement is primarily attributed to the significant spectral narrowing of the fundamental field, which increases the effective Raman gain and overcompensates for the additional insertion losses. By utilizing BRFs with thicknesses of 0.5 and 1 mm, the system achieved stable tuning ranges of approximately 0.24 and 0.3 nm, respectively, with maximum Stokes output powers of 1.24 and 1.05 W. It should be noted that although the absolute wavelength span observed at extreme BRF rotation angles can extend to 2.06 and 1.77 nm, respectively, this is primarily due to intermittent outliers. Both the output wavelength and power exhibit a strict 180° periodicity relative to the BRF rotation angle.
Dislocations in (011)-oriented vertical Bridgman <b> <i>β</i> </b> -Ga2O3 substrates
Dislocations in (011)-oriented β-Ga2O3 substrates grown by the vertical Bridgman method was investigated using x-ray topography (XRT), combined with x-ray reticulography. Transmission XRT reveals dislocations lying on the (001) plane and extending along [010], forming arrays associated with domain boundaries. Dislocations on the (011) plane were also identified but differ from those responsible for line-shaped pits on (001) epilayers. Reflection XRT showed good agreement with transmission XRT and enables classification of dislocation types based on contrast features. Reticulography confirms domain boundaries with misorientation on the order of 10−5 rad, providing insight into defect formation relevant to epi-growth and device performance.
Gd2O3-induced electronic modulation of Cu for efficient oxygen reduction in aluminum–air batteries
A Gd2O3-modified copper-based composite catalyst (Gd2O3–Cu/C) was developed via solvothermal preassembly and high-temperature pyrolysis to overcome the sluggish oxygen reduction reaction (ORR) kinetics of aluminum–air batteries (AABs) and the limitations of Pt-based catalysts. The strong electronic interaction between Gd2O3 and Cu active sites efficiently regulates the electronic structure of the catalyst, reducing its work function and charge transfer resistance; this results in an increase in the valence band electron density, thus promoting a nearly four-electron ORR pathway and ultimately enhancing the overall ORR kinetics. The catalyst exhibited a half-wave potential of 0.82 V, a Tafel slope of 67 mV dec−1, a 90% current retention after 500 min, and outstanding methanol tolerance, demonstrating superior ORR kinetics and durability in alkaline electrolyte. When assembled into an AAB, the Gd2O3–Cu/C catalyst delivered an open-circuit potential of 1.521 V, a peak power density of 65.7 mW cm−2, and a specific capacity of 578.8 mAh g−1, outperforming the commercial Pt/C-based counterpart. Density functional theory calculations revealed that Gd-induced electronic modulation of Cu facilitates electron transfer from Gd2O3 to Cu, positively shifting the d-band center of Cu toward the Fermi level, optimizing the adsorption of ORR species, and thus enhancing the ORR performance. This work introduces a cost-effective and high-performance non-precious metal catalyst for ORR, with application in AABs for emergency power supplies.
Ultrathin fully strained GaN channel high electron mobility transistors on AlN-on-sapphire templates engineered by ferroelectric ScAlN epilayers
In this work, we demonstrate fully strained GaN channel high electron mobility transistors (HEMTs) with superlattice barriers on AlN-on-sapphire templates by plasma-assisted molecular beam epitaxy. Here, ferroelectric Sc0.18Al0.82N epilayers are introduced into the heterostructure to engineer the device performance. Instead of the conventionally thick AlN buffer, an ultrathin Sc0.18Al0.82N layer is positioned between the AlN template and the GaN channel to effectively suppress the leakage at the interface between the secondary epilayers and the AlN template, realizing fully strained epitaxial structures less than 60 nm. Besides, a Sc0.18Al0.82N layer serves as a part of the superlattice barrier with well-defined interfaces, which results in a stronger polarization effect and larger conduction band offset and thus a high carrier density of 3.12 × 1013 cm−2. The processed GaN HEMT engineered by Sc0.18Al0.82N epilayers exhibits direct-current transfer characteristics with an on/off current ratio of ∼106 and distinct counterclockwise ferroelectric hysteresis windows, with a widely tunable threshold voltage ranging from −6.3 to −2.7 V. The fabricated device with a 180-nm T-shaped gate and gate-drain space of 1.5 μm achieves a breakdown voltage of 80 V, a cutoff frequency of 32 GHz, and a maximum oscillation frequency of 70 GHz, respectively. This work provides a new approach for developing next-generation multifunctional transistors on an ultrawide bandgap AlN platform through synergistically integrating ferroelectric gate modulation with a superlattice barrier, offering a promising candidate for highly reliable microwave power electronics with tunable switching characteristics.
Device-area selection of memristive transport regimes in epitaxial Hf0.5Zr0.5O2-based ferroelectric devices
Ferroelectric memristive devices based on hafnia are promising systems for neuromorphic electronics, yet the interplay between polarization-modulated resistive changes and defect-mediated transport often leads to complex and debated switching mechanisms. Here, we investigate this competition in epitaxial Hf0.5Zr0.5O2/La0.67Sr0.33MnO3 heterostructures with Pt top electrodes by combining structural, ferroelectric, and memristive characterization with a statistical analysis across a broad range of device areas spanning three orders of magnitude. We identify two distinct memristive regimes with opposite resistance–voltage chiralities. Small devices exhibit a low-resistance state that scales inversely with area, consistent with area-distributed electronic transport, while larger devices display an area-independent resistance indicative of localized conductive channels. A statistical nucleation model quantitatively captures this behavior and yields a crossover characteristic area of A*≈103μm2. This crossover also correlates with the onset of ferroelectric wake-up for the larger devices, linking conductive-channel nucleation and oxygen-vacancy redistribution within a unified physical picture. These results establish lateral device size as a key parameter controlling the dominant transport mechanism in epitaxial hafnia-based devices.
Improved light extraction and thermal management in thin-film GaAs LEDs using hemispherical ZnSe lenses
High-index optical elements enable improved photon outcoupling from high-refractive index III–V emitters, but their feasibility on electrically driven GaAs light-emitting diodes (LEDs) has been limited by the stringent requirement of near-optical contact between the element and the LED. Here, we demonstrate a practical and reversible integration of a ZnSe hemispherical lens with a thin-film GaAs LED using a spring-preloaded tip/tilt fixture that enables alignment and in situ optical contact monitoring. Integrating the ZnSe hemisphere consistently increases the emitted optical power and external quantum efficiency by a factor of 4.5–5.5 relative to emission into air, while a thin, moderately convex layer of oil used as a reference yields an intermediate enhancement. In addition to improved extraction, the hemisphere also strongly suppresses the current-induced spectral redshift, consistent with reduced self-heating; a bandgap-only estimate indicates that the air-emitting LED operates approximately 10 K hotter than the LED coupled to the hemisphere at 10 mA. Simulations describing the effect of the residual air gap thickness on the enhancement show a rapid degradation of the extraction benefits for gap thicknesses already starting from around 20 nm. These results show that a high-index external hemisphere can simultaneously enhance light extraction and improve thermal stabilization, addressing two coupled limitations in high efficiency GaAs LEDs and thermophotonic devices.
Heterocyclic aromatic amine-modified hole transport layer enables energy level regulation for enhanced performance of deep blue QLEDs
Quantum dots (QDs) exhibit great promise for next-generation displays, yet deep blue quantum dots light-emitting diodes [deep blue QLEDs, CIE (International Commission on illumination) y &lt; 0.06] lag behind red and green counterparts due to energy level mismatches and imbalanced carrier mobility. In this work, 2-aminopyridine was employed at the interface between the hole transport layer and the emitting layer to construct stepwise energy level regulation. The mechanism was elucidated through density functional theory calculations, photophysical characterization, and surface morphology analysis. The modifier deepens the HOMO level of the hole transport layer from −5.75 to −5.97 eV and increases hole mobility from 4.08 × 10−7 to 1.56 × 10−6 cm2 V−1 s−1. The device based on the modified hole transport layer achieved a record external quantum efficiency of 23.16% in deep blue QLED (CIE y = 0.027). Interface modification demonstrates an effective approach to high-efficiency deep blue QLEDs and supports the commercialization of QLEDs.
High-thermal-conductivity polycrystalline diamond grown on GaN via a cyclic-methane-modulation-assisted strategy
The self-heating effect severely limits the performance and reliability of GaN high-electron-mobility transistors (HEMTs). Direct deposition of thin-film polycrystalline diamond (PCD) on GaN is regarded as a promising strategy as it allows the heat spreader to be placed as close as possible to the hotspots. However, rapid grain coalescence during the initial growth stage usually leads to the formation of high-density graphitic carbon phases, which significantly degrades the thermal conductivity (k) of the as-grown diamond films. Here, we report a cyclic-methane-modulation-assisted (CMMA) two-step growth strategy with periodically cycled methane concentration that balances the growth rate and grain quality while suppressing the incorporation of graphite. This approach achieves a remarkably high k of 632 ± 76 W/m K for 2.4-μm-thick PCD on GaN, accompanied by a low thermal boundary resistance of 8.5 ± 0.5 m2 K/GW even with a 5 nm-thick SiNx interlayer. Finite-element simulation predicts a 70 °C reduction in peak temperature for the HEMTs integrated with CMMA-grown diamond, which highlights its substantial potential for effective thermal dissipation in high-power electronic applications.
Probe–suspended membrane resonance model for obtaining out-of-plane shear modulus and prestress in graphene
The out-of-plane shear modulus of two-dimensional (2D) materials is critical for understanding their strain-modulated electronic, optical, and tribological behavior. However, existing experimental methods are limited and often yield inconsistent results due to substrate interference. Here, we introduce a contact-resonance-based methodology utilizing a probe–suspended membrane system to simultaneously measure both the out-of-plane shear modulus and in-plane prestress of 2D material membranes. The membrane's load–deflection response is modeled via a novel cubic equation fitted from numerical simulations. The probe–membrane dynamic system is modeled as a tilted cantilever with normal and lateral springs at its tip, yielding a frequency equation that links resonance frequency to membrane stiffness. Experimental measurements on suspended multilayer graphene under varying loads yield an out-of-plane shear modulus of 4.16 ± 0.30 GPa, consistent with theoretical predictions. The in-plane prestress is observed to decrease with membrane thickness. Pressure-blister tests corroborate that van der Waals attraction from the hole sidewalls is a primary origin of this prestress. This work establishes a precise, nondestructive method for characterizing 2D material mechanical properties with minimal substrate influence, offering fundamental insights for the design and performance evaluation of 2D material-based nanodevices and flexible systems.
Ferroelectric nitrogen-polar ScAlN heterostructures on 4H-SiC enabled by thin AlN buffer layers
The expansive functional landscape of ferroelectric nitrides has sharpened interest in host platforms that can preserve excellent structural quality while extending operation to high-temperature, harsh-environment regimes. 4H-SiC is especially compelling owing to its thermal robustness, high thermal conductivity, and close lattice correspondence with AlN. Here, we report robust ferroelectric ScAlN-on-4H-SiC heterostructures enabled by thin, exceptionally high-quality AlN templating, grown via plasma-assisted molecular beam epitaxy. A 40 nm nitrogen-polar AlN buffer layer on carbon-terminated 4H-SiC yields highly ordered and dense films, providing an abrupt, structurally coherent, true wurtzite interface for ScAlN heteroepitaxy. Across a broad Sc composition range, a single dominant epitaxial orientation and monocrystalline wurtzite character are maintained without detectable secondary phases. Electrical measurements reveal room-temperature ferroelectricity in as-grown films with coercive fields and remanent polarizations comparable to ScAlN films grown directly on conductive substrates. Taken altogether, these findings establish AlN templating on 4H-SiC as a practical route to structurally controllable and reproducible all-epitaxial ferroelectric nitride heterostructures for extreme-environment electronic, acoustic, and memory applications.
Heat superdiffusion in carbon nanotubes
Like many one-dimensional systems, carbon nanotubes are known to exhibit a divergent thermal conductivity as the length of the nanotube is increased, but the precise form of this divergence has so far been disputed, some even arguing for a final convergent conductivity. In this work, the solution given by mode-coupling theory, which precisely describes the heat divergence as a power law for sufficiently large lengths, is clearly revealed in molecular dynamics simulations where the tubes' ends are kept at different temperatures. The precise localization of such an asymptotic power law explains why it has not been found before and helps resolve a long-standing puzzle in nanoscale heat transport. It is estimated to show up in carbon nanotubes of macroscopic lengths, currently achievable experimentally.
Self-powered solar-blind ultraviolet detection and integrated electroluminescence performance of Ga2O3:Er-based devices
Gallium oxide (Ga2O3) exhibits broad application prospects in solar-blind ultraviolet detection and rare-earth-activated electroluminescence (EL). However, the high-density intrinsic defects within Ga2O3 severely limit the development of high-performance photodetectors. Moreover, studies on dual-function devices integrating photodetection with EL remain scarce. Herein, we synthesized surface-wrinkled Er-doped Ga2O3 (Ga2O3:Er) films via thermal decomposition of organic precursors. This undulating morphology enhances the ultraviolet light absorption of films. Additionally, Er doping suppresses oxygen vacancies and modulates the heterojunction band alignment. The constructed self-powered photodetector exhibits a responsivity of ∼3.75 × 103 mA/W, a specific detectivity of ∼1.86 × 1013 Jones, and a response time of ∼30 μs under 254 nm illumination. Moreover, the device exhibits characteristic Er-related EL driven by trap-assisted tunneling mechanisms under high reverse bias. The integrated device has been demonstrated for applications in optical-electrical-optical signal conversion and multi-modal signal response.
Spring-integrated low-frequency ME resonator with strong coupling capability and low equivalent magnetic noise
Resonant magnetoelectric (ME) sensors offer the advantages of high sensitivity and inherent narrow-band filtering capability. However, the development of ultra-low-frequency (ULF) ME resonators combining high mechanical quality factor (Qm), low noise performance, and stable near-ideal boundary conditions remains a significant challenge. In this study, a spring-integrated ULF ME resonator is proposed and systematically investigated. The device consists of an elastic support layer, a piezoelectric layer, and a piezomagnetic layer. The elastic support layer incorporates two meander springs at both ends, creating quasi-free boundary conditions for the central sandwich-structured ME composite and enabling excitation of a high-order bending mode with a substantially reduced resonant frequency. Experimental results confirm the excitation of the third-order bending mode at a low frequency of 1266 Hz, with a calculated Qm of 144.8. In addition, the resonant ME coefficient reaches as high as 1633.5 V/(cm Oe), and the equivalent magnetic noise decreases to 300 fT/√Hz around the resonance frequency, demonstrating great potential for specific-frequency magnetic field detection applications, including signature current identification and underground cable tracing. More importantly, the spring-integrated resonant structure provides fixed boundary conditions and maintains a stable operating frequency during long-term operation.
Proteomics‐Driven Strategies for Proximity‐Inducing Drug Discovery
ABSTRACT In recent years, proximity‐inducing drugs have emerged as a novel therapeutic modality that induces or stabilizes protein‐protein interactions, especially by recruiting effector proteins to specific target proteins, thereby achieving functions beyond traditional inhibitors. The potential of proximity‐inducing drugs extends beyond targeted protein degradation (TPD), as studies have demonstrated their ability to regulate biological processes such as signal transduction, gene transcription, chromatin regulation, and protein trafficking by modulating protein interaction networks. Rational discovery of proximity‐inducing drugs requires clarifying their effects on protein‐protein interactions, determining drug selectivity, and developing suitable ligands for drug construction. Proteomics has become a central technology in drug discovery, enabling global identification of the direct drug targets and systematic characterization of proteome‐wide downstream responses. This provides a more refined map of drug mechanisms. In parallel, advances in machine learning applied to proteomic data, together with the expansion of proteome‐wide ligandability maps, are further accelerating the discovery and optimization of proximity‐inducing drugs. This review summarizes recent advances of proximity‐inducing drugs, with a particular emphasis on how proteomics facilitates target space expansion, drug efficacy optimization, and ligandability discovery, alongside the emerging contributions of machine learning. Collectively, these insights aim to support the rational development of next‐generation proximity‐inducing drugs.
Critical behavior of a novel layered ferromagnetic semiconductor Cr1.17Ga1.47Se4
Layered magnetic semiconductors have attracted considerable interest due to their rich magnetic properties and potential applications in low-dimensional spintronics. Here, we report a novel layered magnetic semiconductor, Cr1.17Ga1.47Se4, featuring CrGa2Se4 slabs interleaved with a partially occupied Cr layer. Transmission spectrum, electrical transport, and magnetization measurements reveal that Cr1.17Ga1.47Se4 is a ferromagnetic semiconductor with an optical bandgap of 1.12 eV and a Curie temperature of 34 K. A comprehensive analysis based on modified Arrott plots, the Kouvel–Fisher method, and scaling relations yields a self-consistent set of critical exponents, β = 0.362, γ = 1.381, and δ = 4.81. These exponents are close to those obtained from renormalization group analysis, indicating that Cr1.17Ga1.47Se4 belongs to the three-dimensional Heisenberg system with long-range magnetic interactions. Our results provide a platform for exploring two-dimensional magnetic semiconductors and provide insights into the nature of magnetism of layered magnetic semiconductors.
Bandgap-dependent defect properties in mixed-halide perovskites
Defects in wide-bandgap perovskite solar cells critically limit device performance, yet their chemical nature and bandgap-dependent evolution remain insufficiently understood. Here, we investigate the defect properties of mixed-halide wide-bandgap perovskite solar cells with representative bandgaps of 1.67, 1.78, and 1.93 eV by systematically tuning the I/Br ratio while maintaining the same FA/Cs mixed-cation framework. Thermal admittance spectroscopy was employed to quantify the defect energy depth and defect-state density in these devices. The results reveal that the defect activation energy increases monotonically with increasing bandgap, indicating the formation of deeper defect states in Br-rich wide-bandgap perovskites. By using p-phenylenediamine diiodide to passivate iodide-vacancy-related defects, defect-mediated nonradiative recombination is significantly suppressed, leading to prolonged carrier lifetimes and improved device performance. These results suggest that iodide-vacancy-related halide defects are the dominant recombination-active defects in mixed-halide wide-bandgap perovskite solar cells. Notably, although iodide-vacancy passivation reduces defect density and improves device performance, its effectiveness gradually diminishes as the bandgap increases, highlighting the increasing difficulty of defect passivation in Br-rich wide-bandgap perovskites.
Unipolar ferroelectric synapses with subfemtojoule energy consumption
Neuromorphic computing demands artificial synapses that combine ultra-low energy consumption with simple modulation schemes. Here, we demonstrate unipolar ferroelectric tunnel junction synapse based on an Au/Cr/HZO/LSMO/STO heterostructure, in which both excitatory and inhibitory plasticity are realized solely by tuning the pulse width, without reversing voltage polarity. This unipolar operation further enables emulation of the Bienenstock–Cooper–Munro learning rule with an enhanced depression effect as well as perceptual functions such as edge detection. Pulse-width-modulated long-term potentiation was leveraged to experimentally emulate Pavlovian conditioning. Moreover, continuous long-term potentiation and long-term depression were achieved by alternately varying the pulse width and were applied to motion detection. This work provides a new pathway for implementing diverse neuromorphic functionalities through simple pulse-width modulation, highlighting the potential of unipolar ferroelectric synapses for efficient in-memory computing systems.
Theoretical strategy for coherent perfect absorption based on photonic time crystals: Interference and energy control
Photonic time crystals (PTCs) are artificial materials whose electromagnetic (EM) properties vary with time, enabling the realization of physical phenomena and energy conversion devices through the utilization of the time dimension. A theoretical strategy based on the PTCs for achieving coherent perfect absorption (CPA) is introduced in this Letter, enabling controllable switching between energy amplification (EA) and CPA. A single EM wave propagating within the PTC momentum bandgap absorbs pump energy and grows exponentially, thereby generating EA. Signal wave and control one generate coherent interference within the PTCs, enabling CPA by controlling the phase difference and intensity of the two waves. Further research reveals that increasing the PTCs' period effectively enhances performance of CPA, while altering the control wave's phase and intensity facilitate mutual switching between CPA and EA. The study employs theoretical calculations using the transfer matrix method to establish a PTC-based CPA strategy, while analyzing the generation processes of EA and CPA within the PTCs via the finite-difference time-domain method. This research expands the field of PTC studies, achieves controllable switching between PTC-based EA and CPA, and demonstrates the physical mechanism based on energy control, conversion, and EM wave interference within the PTCs.
Low optical loss electrical isolation for multi-section monolithic GaSb-based photonic circuits
Monolithic photonic integrated circuit (PIC) platforms exploiting III–V materials combine passive and active waveguide structures in multi-section optoelectronic device architectures. Their operation requires high electrical isolation between adjacent functional sections without compromising the optical signal. This fundamental requirement is addressed for GaSb-based waveguides, which are known to exhibit high conductivity of p-type layers, reducing the electrical isolation capability. To this end, a co-designed electrical–optical isolation strategy based on using deeply etched strip waveguides combined with adiabatic ridge-to-strip waveguide tapers in GaSb-based multiple-quantum well heterostructures is proposed. While deep etching alone enables isolation resistances of up to 40 kΩ, it severely degrades optical propagation. By introducing optimized adiabatic tapers, we demonstrate good optical performance as single mode continuous-wave lasing in a two-section device with integrated absorber, while maintaining an isolation resistance of 17.3 kΩ; this corresponds to an approximately 17-fold improvement over previously reported GaSb two-section devices. The approach establishes a critical building block for the development of monolithic GaSb-based PICs operating above 2 μm.