Search Results (361)

Laser slicing has emerged as a promising low-kerf and low-damage technique for SiC wafer fabrication; however, its effects on the crystal integrity, near-surface modification, and charge-transport properties require further clarification. Here, a heavily N-doped 4° off-axis 4H-SiC wafer was sliced using an ultraviolet (UV) picosecond laser, and both laser-irradiated and laser-sliced surfaces were comprehensively characterized. X-ray diffraction and pole figure measurements confirmed that the 4H stacking sequence and macroscopic crystal orientation were preserved after slicing. Raman spectroscopy, including analysis of the folded transverse-optical and longitudinal-optical phonon–plasmon coupled modes, enabled dielectric function fitting and determination of the plasmon frequency, yielding a free-carrier concentration of ~3.1 × 10¹⁸ cm⁻³. Hall measurements provided consistent carrier density, mobility, and resistivity, demonstrating that the laser slicing process did not degrade bulk electrical properties. Multi-scale Atomic Force Microscopy (AFM), Angle-Resolved X-Ray Photoelectron Spectroscopy (ARXPS), Secondary Ion Mass Spectrometry (SIMS), and Transmission Electron Microscopy (TEM)/Selected Area Electron Diffraction (SAED) analyses revealed the formation of a near-surface thin amorphous/polycrystalline modified layer and an oxygen-rich region, with significantly increased roughness and thicker modified layers on the hilly regions of the sliced surface. These results indicate that UV laser slicing maintains the intrinsic crystalline and electrical properties of 4H-SiC while introducing localized nanoscale surface damage that must be minimized by optimizing the slicing parameters and the subsequent surface-finishing processes. Full article

This study presents an experimental framework for mapping the air-gap magnetic flux in electric machines operating under controlled eccentricity and tilt conditions. A six-degree-of-freedom industrial robotic arm positions the rotor, while the stator accommodates a dense single-axis Hall-sensor array. Synchronous data acquisition at 10 kHz captures magnetic-field dynamics during torque-producing excitation. A coordinate-transformation method synthesises virtual rotor poses from a limited set of physical measurements, eliminating the need for exhaustive mechanical scanning. The proposed approach generates pose-resolved RMS and THD maps, together with harmonic amplitude and phase signatures, thereby revealing localised asymmetries and phase-decoherence effects that are not predicted by idealised finite-element models. In a custom PMSM-like prototype, the local RMS value doubles (from 31 mT to 64 mT), while the THD increases by more than 25% across displacement and tilt grids. These findings provide quantitative experimental evidence of misalignment-induced magnetic-field symmetry breaking, supporting model validation and digital-twin calibration for traction, aerospace, and robotic applications. Full article

An ultrathin Al layer was introduced into AZO/Cu/AZO films to further enhance the optoelectronic performance. The AZO/Al/Cu/AZO films were deposited on glass substrates by DC and RF magnetron sputtering; the microstructure and optoelectronic properties were analyzed by XRD, SEM, AFM, TEM, visible spectrophotometer, and Hall effect measurement system. The results indicated that the Al layer played a crucial role in modulating the crystallization behavior and optoelectronic properties of the films, exhibiting a distinct thickness-threshold effect. At an Al layer thickness of 1 nm, the film exhibited optimal optoelectronic performance, achieving a high F_OM of 0.71 Ω⁻¹, a high transmittance of 85%, and a low resistivity of 5.7 × 10⁻⁵ Ω·cm. However, when the Al layer thickness exceeded 1 nm, the crystallinity of the films deteriorated significantly, the grain boundary scattering and light absorption effect enhanced, leading to the deterioration of photoelectric properties. The introduction of the Al layer significantly improved the stability of the films, and the AZO/Al(2 nm)/Cu/AZO film exhibited the best temporal stability after being exposed to air for 20 months. Full article

The growing adoption of renewable energy conversion systems and smart infrastructures has increased the demand for accurate monitoring solutions to ensure system performance and reliability, as well as seamless integration with cloud-based platforms. Voltage and current sensing are central to this task; however, sensor selection often involves a trade-off between cost and measurement precision. Rather than comparing technologies as equivalent options, this study investigates the practical impact of using low-cost versus high-precision sensors in electrical power generation monitoring. The evaluation includes representative low-cost sensors and high-precision alternatives based on instrumentation amplifiers and a closed-loop Hall-effect transducer. All sensors were characterized under controlled laboratory conditions and analyzed using statistical indicators, including MAE, RMSE, MAPE, and R². Results show that high-precision sensors achieved R² > 0.97 and MAPE < 4%, whereas low-cost sensors showed R² as low as 0.73 and errors exceeding 10% under dynamic irradiance conditions. Low-cost sensors present deviations of 5–8% in RMS measurement, while high-precision sensors maintain error below 1%. Full article

To optimize the design of silicon carbide (SiC) devices for applications in space and nuclear environments, this work introduces varying degrees of lattice damage into SiC through controlled irradiation conditions, with Raman spectroscopy revealing its damage evolution behavior and quantitatively characterizing the increasing trend of disorder with irradiation fluences. Fine analysis of the A₁(LO) phonon mode demonstrates that proliferation of irradiation-induced acceptor centers and accumulation of scattering defects lead to significant attenuation of carrier concentration and mobility (cross-verified by Hall effect measurements), thereby causing degradation in electrical conductivity of SiC. Subsequent electrical testing confirms an orders-of-magnitude reduction in conductivity, establishing a quantitative correlation model with total disorder quantified by the DI/DS model. The non-destructive Raman technique enables simultaneous acquisition of material damage characteristics and quantitative electrical performance degradation, providing a predictive framework for the evolution of electrical behavior for SiC under irradiation damage, with significant implications for optimizing irradiation-hardened device designs. Full article

We study thrust production in a single-fluid magnetohydrodynamic (MHD) thruster with Hall-type coaxial geometry and show how velocity–field alignment and magnetic topology set the operating regime. Starting from the momentum equation with anisotropic conductivity, the axial Lorentz force density reduces to $f_z={\sigma }_{\theta z}{E}_z{B}_r(\chi -1)$, with the motional-field ratio $\chi \equiv \left(u{B}_r\right)/E_z$. Hence, net accelerating force ($f_z>0$) is achieved if and only if the motional electric field $E_m=u{B}_r$ exceeds the applied axial bias $E_z$ ($\chi >1$), providing a compact, testable design rule. We separate alignment diagnostics (cross-helicity $h_c=\mathit{u}·\mathit{B}$) from the thrust criterion ($\chi$) and generate equation-only axial profiles for $\chi \left(z\right)$, $j_{\theta }\left(z\right)$, and $f_z\left(z\right)$ for representative parameters. In a baseline case $(E_z=150\mathrm{V}{\mathrm{m}}^{-1},{\sigma }_{\theta z}=50\mathrm{S}{\mathrm{m}}^{-1},u_0=12\mathrm{km}{\mathrm{s}}^{-1},B_{r0}=0.02\mathrm{T},L=0.10\mathrm{m})$, the $\chi >1$ band spans $\approx 21.2\%$ of the channel; a lagged correlation peaks at $\Delta z^{★}\approx 8.82\mathrm{mm}$$(C_{HU}=0.979)$, and ${\int }_0^L{f}_z\mathrm{d}z$ is slightly negative—indicating that enlarging the $\chi >1$ region or raising ${\sigma }_{\theta z}$ are effective levers. We propose a reproducible validation pathway (finite-volume MHD simulations and laboratory measurements: PIV, Hall probes, and thrust stand) to map $f_z$ versus $\chi$ and verify the response length. The framework yields concrete design strategies—$B_r\left(z\right)$ shaping where u is high, conductivity control, and modest $E_z$ tuning—supporting applications from station-keeping to deep-space cruise. Full article

Large-scale applications of multi-material manufacturing technology face many challenges. One major issue is how to reuse the mixed powder left after printing. In this study, we propose using an effective structure design to compensate for the performance loss of reused materials, thereby achieving the purpose of reusing premixed waste powder in certain non-critical thermal management applications. Taking Cu and Ni premixture powder as an example, some explorations were then conducted on the feasibility of the proposed concept. The morphological inspection confirms that the powder mixture exhibits satisfactory homogeneity, while the Hall flow rate measurements reveal that its flowability is closer to that of pure Ni. The compression tests show that the fabricated Cu-Ni specimens have good energy absorption, whereas tensile tests reveal their favorable ductility. The numerical analysis indicates that the effect of convection heat transfer is much greater than that of conduction heat transfer. Heat transfer experiments show that the Cu-Ni heat exchanger exhibits comparable performance to pure Cu, with a heat transfer effectiveness deviation of less than 1.3%. Previous results indicate that effective structure design can offset the loss of material properties, allowing premixed powders to be utilized in heat exchanger production as a means of recycling waste powders. Full article

Recent advances in nanotechnology, including the development of nanoparticles, thin films, and superlattices, have revitalized research in thermoelectricity by enabling independent control of thermal and electrical transport, overcoming longstanding efficiency limitations and expanding opportunities for sustainable energy generation and miniaturized device applications. Tin dioxide (SnO₂) has recently attracted increasing attention as a thermoelectric material owing to its properties, such as high-temperature chemical and structural stability, non-toxicity, and the abundance of constituent elements. Current research efforts have been directed toward enhancing its thermoelectric performance through strategies such as elemental doping, nanostructuring, strain engineering, and the development of composite systems. In this study, we investigate the effects of Mg substitutional doping on the thermoelectric characteristics of SnO₂. We synthesize undoped and Mg-doped SnO₂ nanoparticles (0.05%, 0.10%, and 0.15%) using a straightforward hydrothermal technique. The investigation of the undoped and doped materials revealed that SnO₂ possesses a tetragonal rutile-type structure, as determined through structural and morphological examination. The crystalline size of all of the samples decreases as the Mg doping concentration is increased. Hall measurement and Seebeck coefficient measurements have been employed for assessing the thermoelectric characteristics. As the Mg content increased, both the Seebeck coefficient and electrical conductivity value increased from −20 $\mathsf{\mu }$V/K to −91 $\mathsf{\mu }$V/K and 29.8 S/cm to 112.6 S/cm, confirming the presence of semiconductor behavior. The 0.15% Mg-doped sample demonstrates the highest power factor when evaluated at a temperature of 150 K, yielding a value of 9.4 $\times {10}^{-5}$ WK⁻²m⁻¹. Full article

Beta-gallium oxide (β-Ga₂O₃) is a semiconductor with an ultra-wide bandgap, high optical transparency, and excellent electrical properties, which can be finely tuned for a wide range of electronic devices. This study optimized the process conditions for fabricating β-Ga₂O₃ thin films with desired electrical characteristics. β-Ga₂O₃ films were deposited on (100) Si substrates via RF magnetron sputtering with varying O₂ flow rates and post-annealed at temperatures ranging from 600 °C to 800 °C. The structural and electrical properties of the films were analyzed using X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), and Hall effect measurements. The XRD results confirmed the formation of nanocrystalline β-Ga₂O₃, with variations in peak intensities and shifts observed based on O₂ flow rates. The films exhibited carrier concentrations exceeding 5 × 10²² cm⁻³, mobilities ranging from 50 to 115 cm²/Vs, and resistivity around 1 × 10⁻⁶ Ω⋅cm. This study demonstrates that the electrical properties of β-Ga₂O₃ thin films can be modulated during the deposition and post-annealing processes. The ability to control these properties underscores the potential of β-Ga₂O₃ for advanced applications in high-performance high-power devices and optoelectronic devices such as deep ultraviolet photodetectors. Full article

In this study, high-conductivity W-doped Ga₂O₃ thin films were successfully fabricated by directly depositing a composition of Ga₂O₃ with 10.7 at% WO₃ (W:Ga = 12:100) using electron beam evaporation. The resulting thin films were found to be amorphous. Due to the ohmic contact behavior observed between the W-doped Ga₂O₃ film and platinum (Pt), Pt was used as the contact electrode. Current-voltage (J-V) measurements of the W-doped Ga₂O₃ thin films demonstrated that the samples exhibited significant current density even without any post-deposition annealing treatment. To further validate the excellent charge transport characteristics, Hall effect measurements were conducted. Compared to undoped Ga₂O₃ thin films, which showed non-conductive characteristics, the W-doped thin films showed an increased carrier concentration and enhanced electron mobility, along with a substantial decrease in resistivity. The measured Hall coefficient of the W-doped Ga₂O₃ thin films was negative, indicating that these thin films were n-type semiconductors. Energy-Dispersive X-ray Spectroscopy was employed to verify the elemental ratios of Ga, O, and W in the W-doped Ga₂O₃ thin films, while X-ray photoelectron spectroscopy analysis further confirmed these ratios and demonstrated their variation with the depth of the deposited thin films. Furthermore, the W-doped Ga₂O₃ thin films were deposited onto both p-type and heavily doped p⁺-type silicon (Si) substrates to fabricate heterojunction diodes. All resulting devices exhibited good rectifying behavior, highlighting the promising potential of W-doped Ga₂O₃ thin films for use in rectifying electronic components. Full article

Extreme ultraviolet (EUV) pellicles must withstand intense thermal stress during exposure due to their limited heat dissipation, which results from their ultrathin geometry and the vacuum environment within EUV scanners. To address this challenge, we investigated the crystalline phase-dependent emissivity of nanometer-thick molybdenum disilicide (MoSi₂) membranes. Membranes exhibiting amorphous, hexagonal, and tetragonal phases were independently prepared via controlled annealing, and their thermal radiation properties were evaluated using heat-load testing under emulated EUV scanner conditions. The Hall effect measurements revealed distinct variations in carrier density and mobility across phases, which were theoretically correlated with emissivity using the Lorentz–Drude model. The results demonstrate that emissivity increases in the hexagonal phase due to increased carrier density and reduced scattering, offering improved thermal radiation performance. These findings establish the phase engineering of conductive silicides as a viable strategy for enhancing radiative cooling in EUV pellicles and offer a theoretical framework applicable to other high-temperature nanomaterials. Full article

This study investigates the influence of post-deposition thermal annealing temperature on the crystal structure, chemical composition, and electrical performance of solution-processed indium oxide (In₂O₃) thin films. Based on thermogravimetric analysis (TGA) of the precursor solution, annealing temperatures of 350, 450, and 550 °C were adopted. The resulting In₂O₃ films were characterized using ultraviolet–visible (UV–Vis) spectroscopy, atomic force microscopy (AFM), Raman spectroscopy, and Hall-effect measurements to evaluate their optical, morphological, crystalline polymorphism, and electrical properties. The results revealed that the film annealed at 450 °C exhibited a field-effect mobility of 4.28 cm²/V·s and an on/off current ratio of 2.15 × 10⁷. The measured hysteresis voltages were 3.11, 1.80, and 0.92 V for annealing temperatures of 350, 450, and 550 °C, respectively. Altogether, these findings indicate that an annealing temperature of 450 °C provides an optimal balance between the electrical performance and device stability for In₂O₃-based thin-film transistors (TFTs), making this condition favourable for high-performance oxide electronics. Full article

The degradation of the electronic properties of semiconductor materials and electronic devices under neutron irradiation is a critical issue for the development of electronic systems intended for use in nuclear and thermonuclear energy facilities. This study presents a methodology for real-time measurement of the electrical parameters of semiconductor structures during neutron irradiation in a high-flux reactor environment. A specially designed irradiation fixture with an electrical measurement system was developed and implemented at the WWR-K research reactor. The system enables simultaneous measurement of electrical conductivity and the Hall effect, with automatic temperature control and remote data acquisition. The sealed fixture, equipped with radiation-resistant wiring and a temperature control, allows for continuous measurement of remote material properties at neutron fluences exceeding 10¹⁸ cm⁻², eliminating the limitations associated with post-irradiation handling of radioactive samples. The technique was successfully applied to the two different InGaAs-based heterostructures, revealing distinct mechanisms of radiation-induced modification: degradation of mobility and carrier concentration in the InGaAs quantum well structure on GaAs substrate, and transmutation-induced doping effects in the heterostructure on InP substrate. The developed methodology provides a reliable platform for evaluating radiation resistance and optimizing materials for magnetic sensors and electronic components designed for high-radiation environments. Full article

We report high-resolution, cavity-enhanced direct frequency comb Fourier transform spectroscopy of cold acetylene (C₂H₂) molecules in a planar supersonic jet expansion. The experiment is based on a near-infrared frequency comb with a 300 MHz effective repetition rate, matched to a high-finesse enhancement cavity traversing the jet. The rotational and translational cooling of acetylene was achieved via expansion in argon carrier gas through a slit nozzle. By interleaving successive mode-resolved spectra measured at different comb repetition rates, we retrieved full absorption line profiles. Spectroscopic analysis reveals sharp, Doppler-limited transitions corresponding to a jet core rotational temperature below 7 K. Frequency comb and cavity stabilization were achieved through active Pound–Drever–Hall locking and mechanical vibration damping, enabling a spectral precision better than 2 MHz, limited by the vibrations induced by the pumping system. The demonstrated sensitivity reaches a minimum detectable absorption of 7.8 × 10⁻⁷ cm⁻¹ over an 18 m effective path length in the jet core. This work illustrates the potential of cavity-enhanced direct frequency comb spectroscopy for precise spectroscopic characterization of cold supersonic expansions, with implications for studies in molecular dynamics, reaction kinetics, and laboratory astrophysics. Full article

This study constructed an integrated underwater pipeline monitoring system, which combines pipeline posture sensing modules and pipeline leakage detection modules. The proposed system can achieve the real-time monitoring of pipeline posture and the comprehensive assessment of pipeline damage. By deploying pipeline posture sensing and leakage detection modules in array configurations along an underwater pipeline, information related to pipeline posture and flow variations is continuously collected. An array of inertial sensor nodes that form the pipeline posture sensing system is used for real-time pipeline posture monitoring. The system measures underwater motion signals and obtains bending and buckling postures using posture algorithms. Pipeline leakage is evaluated using flow and water temperature data from Hall sensors deployed at each node, assessing pipeline health while estimating the location and area of pipeline damage based on the flow values along the nodes. The human–machine interface designed in this study for underwater pipelines supports automated monitoring and alert functions, so as to provide early warnings for pipeline postures and the analysis of damage locations before water supply abnormalities occur in the pipelines. Underwater experiments validated that this system can precisely capture real-time postures and damage locations of pipelines using sensing modules. By taking flow changes at these locations into consideration, the damage area with an error margin was estimated. In the experiments, the damage areas were 8.04 cm² to 25.96 cm², the estimated results were close to the actual area trends (R² = 0.9425), and the area error was within 5.16 cm² (with an error percentage ranging from −20% to 26%). The findings of this study contribute to the management efficiency of underwater pipelines, enabling more timely maintenance while effectively reducing the risk of water supply interruption due to pipeline damage. Full article