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arXiv 2025年

作者： Arnab, Khandakar Aaditta Stephens, Megan Maxfield, Isaac Lee, Channyung Ertekin, Elif Frodason, Ymir K. Varley, Joel B. Scarpulla, Michael A. Department of Materials Science and Engineering University of Utah Salt Lake CityUT84112 United States Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Materials Research Laboratory University of Illinois at Urbana-Champaign UrbanaIL61801 United States Centre for Materials Science and Nanotechnology Physics University of Oslo Oslo Norway Lawrence Livermore National Laboratory LivermoreCA93106 United States Department of Electrical and Computer Engineering University of Utah Salt Lake CityUT84112 United States

β-gallium oxide (β-Ga2O3) is of high interest for power electronics because of its unique combination of melt growth, epitaxial growth, n-type dopability, ultrawide bandgap, and high critical field. Optimization of crystal growth processes to promote beneficial defects and suppress harmful ones requires accurate quantitative modelling of both native and impurity defects. Herein we quantitatively model defect concentrations as a function of bulk crystal growth conditions and demonstrate the necessity of including effects such as bandgap temperature dependence, chemical potentials from thermochemistry, and defect vibrational entropy in modelling based on defect formation energies computed by density functional theory (DFT) with hybrid functionals. Without these contributions, grossly-erroneous and misleading predictions arise, e.g. that n-type doping attempts would be fully compensated by Ga vacancies. Including these effects reproduces the experimental facts that melt-grown Sn-doped β-Ga2O3 crystals are conductive with small compensation while annealing the same crystals in O2 at intermediate temperatures renders them insulating. To accomplish this modeling, we developed a comprehensive modelling framework (KROGER) based on calculated defect formation energies and flexible thermodynamic conditions. These capabilities allow KROGER to capture full and partial defect equilibria amongst native defects and impurities occurring during specific semiconductor growth or fabrication processes. We use KROGER to model 873 charge-states of 259 defects involving 19 elements in conditions representing bulk crystal growth by edge-fed growth (EFG) and annealing in oxygen. Our methodology is transferrable to a wide range of materials beyond β-Ga2O3. The integration of thermodynamic and first-principles modelling of point defects provides insight into optimization of point defect populations in growth and processing. Copyright © 2025, The Authors. All rights reserved.

关键词： Point defects

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X-ray scattering investigation of hydride surface segregation in epitaxial Nb films

arXiv

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arXiv 2025年

作者： Garcia-Wetten, David A. Ryan, Philip J. Kim, Jong Woo Goronzy, Dominic P. Reinertsen, Roger J. Hersam, Mark C. Bedzyk, Michael J. Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Argonne National Laboratory ArgonneIL60439 United States Department of Chemistry Department of Electrical and Computer Engineering Northwestern University EvanstonIL60208 United States Department of Physics and Astronomy Northwestern University EvanstonIL60208 United States

Hydride precipitation in niobium-based, superconducting circuits is a damaging side-effect of hydrofluoric acid treatments used to clean and thin the Nb surface oxides and Si oxides. The precipitate microstructure is difficult to probe because of the high hydrogen mobility in the niobium matrix. In particular, destructive techniques used to prepare samples for elemental depth profiling can change the hydride structure. Here, we use X-ray surface scattering to non-destructively probe the depth distribution of precipitates in hydrided, epitaxial, niobium thin films. We find that the niobium hydride is confined within the top 10 nm of the surface, and that the domains are discretely tilted with respect to the film’s surface crystallographic orientation. © 2025, CC BY.

关键词： Surface segregation

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Fiber optic SERS sensors for rapid detection and identification of Salmonella in turkey products 25

Fiber optic SERS sensors for rapid detection and identificat...

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Optical Fibers and Sensors for Medical Diagnostics, Treatment, and Environmental Applications XXV 2025

作者： Abuhelwa, Mai Chenggeer, Fnu Bandara, Adheesha Liu, Jiayu Willoughby, Paige Carlson, Anna Trout, Kate E. Morey, Amit Kinzel, Ed Mustapha, Azlin Almasri, Mahmoud Department of Electrical Engineering and Computer Science University of Missouri ColumbiaMO65211 United States Food Science Program University of Missouri ColumbiaMO65211 United States Cargill Inc WichitaKS67202 United States College of Health Sciences University of Missouri ColumbiaMO65211 United States Department of Poultry Science Auburn University AuburnAL36849 United States University of Notre Dame IN46556 United States

ISBN: (纸本)9781510683686

This study validates a fiber optics-based Surface Enhanced Raman Spectroscopy (SERS) sensor for detecting Salmonella in raw turkey samples. The sensor uses nanoantenna arrays on a side-polished optical fiber core with a fixed periodicity of 0.77 μm to maximize the SERS signal intensity. A 3D-printed chamber and microstructure optimize light reflection, improving sensitivity. The sensor detects Salmonella at 0.4-0.5 CFU/ml in 10 minutes, offering cost-effective, portable pathogen detection. © 2025 SPIE.

关键词： Multimode fibers

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Enhancing Power Factor in n-type Chalcopyrite CdSnAs₂ Thermoelectrics via Supercooled Solidification

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ACS Applied Energy materials 2025年

作者： Kishida, Shoki Okamoto, Norihiko L. Katsube, Ryoji Nagaoka, Akira Sumiyoshi, Isshin Nishioka, Kensuke Ichitsubo, Tetsu Nose, Yoshitaro Department of Materials Science and Engineering Kyoto University Kyoto 606-8501 Japan Institute for Materials Research Tohoku University Sendai 980-8577 Japan Department of Materials Process Engineering Nagoya University Nagoya 464-8603 Japan Electrical and Electronic Engineering Program University of Miyazaki Miyazaki 889-2192 Japan GX Research Center University of Miyazaki Miyazaki 889-2192 Japan

The practical application of thermoelectric (TE) materials is often limited by the relatively underdeveloped performance of n-type materials compared to their p-type counterparts. Chalcopyrite CdSnAs₂ is a promising n-type semiconductor for thermoelectric applications owing to its narrow bandgap around 0.3 eV and exceptionally high electron mobility of 10³-10⁴ cm² V^-1 s^-1. In this study, we investigated the crystal growth, microstructure, and thermoelectric properties of CdSnAs₂. Contrary to conventional understanding of unidirectional melt growth, CdSnAs₂ samples grown at higher cooling rates exhibited better crystallinity, whereas some cracks were observed in those cooled more slowly. Thermal analyses revealed that a phase transition from sphalerite to chalcopyrite occurred after solidification in slowly cooled samples, resulting in the formation of dislocations and cracks due to lattice mismatch between the phases. In contrast, rapid cooling induced supercooling, which lowered the solidification temperature and enabled the phase transition to occur in the presence of a residual liquid phase, thereby leading to a more favorable microstructure. As a result, the sample grown at the highest cooling rate (7.6 K min^-1) achieved an ultrahigh power factor of 3180 μW m^-1 K^-2 at 600 K and a peak ZT of 0.59 at 682 K. The power factor of CdSnAs₂ surpasses that of conventional binary n-type TE materials such as SnSe and PbTe, underscoring its strong potential for intermediate-temperature thermoelectric applications. © 2025 American Chemical Society.

关键词： energy harvesting n-type thermoelectrics solid−solid phase transition supercooling thermal analysis ultrahigh mobility

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Spectroscopic photoacoustic denoising framework using hybrid analytical and data-free learning method

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Photoacoustics 2025年 44卷 100729页

作者： Lin, Fangzhou Gao, Shang Tang, Yichuan Ma, Xihan Murakami, Ryo Zhang, Ziming Obayemi, John D. Soboyejo, Winston O. Zhang, Haichong K. Department of Robotics Engineering Worcester Polytechnic Institute 100 Institute Road WorcesterMA01609 United States Department of Electrical & Computer Engineering Worcester Polytechnic Institute 100 Institute Road WorcesterMA01609 United States 60 Prescott Street WorcesterMA01605 United States Department of Mechanical & Materials Engineering Worcester Polytechnic Institute 100 Institute Road WorcesterMA01609 United States Department of Computer Science Worcester Polytechnic Institute 100 Institute Road WorcesterMA01609 United States

Spectroscopic photoacoustic (sPA) imaging uses multiple wavelengths to differentiate and quantify chromophores based on their unique optical absorption spectra. This technique has been widely applied in areas such as vascular mapping, tumor detection, and therapeutic monitoring. However, PA imaging is highly susceptible to noise, leading to a low signal-to-noise ratio (SNR) and compromised image quality. Furthermore, low SNR in spectral data adversely affects spectral unmixing outcomes, hindering accurate quantitative PA imaging. Traditional denoising techniques like frame averaging, though effective in improving SNR, can be impractical for dynamic imaging scenarios due to reduced frame rates. Advanced methods, including learning-based approaches and analytical algorithms, have demonstrated promise but often require extensive training data and parameter tuning. Moreover, spectral information preservation is unclear, limiting their adaptability for clinical usage. Additionally, training data is not always accessible for learning-based methods. In this work, we propose a Spectroscopic Photoacoustic Denoising (SPADE) framework using hybrid analytical and data-free learning method. This framework integrates a data-free learning-based method with an efficient BM3D-based analytical approach while preserving spectral integrity, providing noise reduction, and ensuring that functional information is maintained. The SPADE framework was validated through simulation, phantom, in vivo, and ex vivo studies. These studies demonstrated that SPADE improved image SNR by over 15 dB in high noise cases and preserved spectral information (R > 0.8), outperforming conventional methods, especially in low SNR conditions. SPADE presents a promising solution for preserving the accuracy of quantitative PA imaging in clinical applications where noise reduction and spectral preservation are critical. © 2025 The Authors

关键词： Image denoising

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Gigahertz directional light modulation with electro-optic metasurfaces

arXiv

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arXiv 2025年

作者： Lin, Sam Chen, Yixin Hwang, Taeseung Upadhyay, Anant Rady, Ramy Dolt, David Palermo, Samuel Entesari, Kamran Madsen, Christi Wong, Zi Jing Lan, Shoufeng Department of Materials Science and Engineering Texas A&M University College StationTX77843 United States Department of Electrical and Computer Engineering Texas A&M University College StationTX77843 United States Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Department of Aerospace Engineering Texas A&M University College StationTX77843 United States

Active metasurfaces promise spatiotemporal control over optical wavefronts, but achieving high-speed modulation with pixel-level control has remained an unmet challenge. While local phase control can be achieved with nanoscale optical confinement, such as in plasmonic nanoparticles, the resulting electrode spacings lead to large capacitance, limiting speed. Here, we demonstrate the operation of a gigahertz-tunable metasurface for beam steering through local control of metasurface elements in a plasmonic-organic hybrid architecture. Our device comprises a corrugated metallic slot array engineered to support plasmonic quasi-bound states in the continuum (quasi-BICs). These plasmonic quasi-BICs provide ideal optical confinement and electrical characteristics for integrating organic electro-optic (OEO) materials like JRD1 and have not been previously utilized in optical metasurfaces. We obtain a quasi-static resonance tunability of 0.4 nm/V, which we leverage to steer light between three diffraction orders and achieve an electro-optic bandwidth of ~4 GHz, with the potential for further speed improvements through scaling rules. This work showcases on-chip spatiotemporal control of light at the sub-micrometer and gigahertz level, opening new possibilities for applications in 3D sensing and high-speed spatial light modulation. © 2025, CC BY.

关键词： Plasmonic nanoparticles

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Strain-enhanced dynamic regulation of chiroptical responses in 3D suspended nested metamaterials

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Optics Express 2025年第11期33卷 23440-23451页

作者： Bo Li ShiLong Duan QiuShun Zou RuanSheng Guo YiMin Chen ChenJie Gu PeiQing Zhang Xiang Shen Faculty of Electrical Engineering and Computer Science Ningbo University Ningbo 315211 China Laboratory of Infrared Material and Devices Zhejiang Key Laboratory of Advanced Optical Functional Materials and Devices Advanced Technology Research Institute Ningbo University Zhejiang 315211 China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China Hefei Anhui 230027 China

Three-dimensional (3D) chiral metamaterials, which exhibit strong chiroptical responses, have attracted tremendous attention in the broad fields of next-generation photonic devices and chiroptical spectroscopy techniques. There is an urgent need for a novel fabrication approach that enables the rapid and straightforward preparation of 3D chiral nanostructures, along with a robust strategy for achieving dynamic regulation. Here, we proposed a strain-enhanced strategy for dynamically regulating the chiroptical responses of 3D suspended nested metamaterials from the transformation of a 2D precursor. The local strain enhancement could effectively resolve the bottleneck of insufficient strain and low precision for the buckling strain self-assembly. The changing morphology and circular dichroism (CD) of 3D suspended chiral metamaterials were analyzed under the impact of a strain-enhanced effect. Then, the uplifted heights of these 3D nanostructures increased with the substrate's pre-strain ( ɛ pre ). Its CD reached up to 0.79, mainly resulting from ring electric dipoles. Interestingly, the chiroptical responses of 3D nanopyramids were regulated dynamically by controlling the substrate's pre-strain. Such a strategy provides a new pathway for achieving high-performance chiral metamaterials and offers promising applications in circularly polarized light detection, super-chiral light sources, optical communication, and advanced nanophotonic systems.

关键词： Holographic displays Luminescent materials Negative index materials Optical properties Photonic devices Refractive index

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Visual Control and Mapping for UAV-Based Platform Inspection

Visual Control and Mapping for UAV-Based Platform Inspection

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International Conference on Unmanned Aircraft Systems (ICUAS)

作者： Leonardo A. Fagundes Carlos M. Soria Raquel F. Vassallo Alexandre S. Brandão Department of Electrical Engineering Graduate Program on Computer Science Federal University of Viçosa Viçosa MG Brazil Facultad de Ingeniería Instituto de Automática Universidad Nacional de San Juan Argentine Department of Electric Engineering Federal University of Espirito Santo Vitória ES Brazil

ISBN: (数字)9798331513283

ISBN: (纸本)9798331513290

Autonomous take-off and landing capabilities are crucial in UAV vision-based missions, ensuring adaptive navigation, especially in challenging environments where realtime identification and interaction with a variety of landing platforms are required. In this context, this paper presents a servo-visual controller that uses pattern detection and color segmentation techniques to identify take-off/landing platforms and estimate their current orientation. The proposed system was subjected to experimental validation with four platforms positioned in different orientations, heights, and positions, demonstrating its versatility in various conditions. Our study addresses the Flying Robots Trial League challenge, which emulates mapping and inspection tasks in offshore platforms.

关键词： Visualization Offshore installations Navigation Color Inspection Autonomous aerial vehicles Aircraft Drones Aerospace control

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Thermally Conductive electrically Insulating Electronics Packaging for Water Immersion Cooling

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IEEE Transactions on Components, Packaging and Manufacturing Technology 2025年

作者： Gebrael, Tarek Gamboa, Arielle R. Hoque, Muhammad Jahidul Aflatounian, Shayan Huitink, David Pilawa-Podgurski, Robert Miljkovic, Nenad University of Illinois Department of Mechanical Science and Engineering UrbanaIL61801 United States University of Arkansas Department of Mechanical Engineering FayettevilleAR72701 United States University of California Department of Electrical Engineering and Computer Sciences BerkeleyCA94720 United States University of Illinois Department of Electrical and Computer Engineering UrbanaIL61801 United States University of Illinois Materials Research Laboratory UrbanaIL61801 United States Institute for Sustainability Energy and Environment UrbanaIL61801 United States Air Conditioning and Refrigeration Center UrbanaIL61801 United States 744 Moto-oka Nishi-ku Fukuoka819-0395 Japan

Power densification is making thermal design a key step in the development of future electrical devices. Systems such as data centers and electric vehicles are generating more heat, which requires efficient cooling to maintain the electronics at temperatures below their limits and to ensure reliability. Immersion cooling has emerged as a promising thermal management technique that brings the coolant closer to the heat-generating elements, hence reducing thermal impedance and improving cooling. Although the dielectric liquid coolants used in immersion cooling do not compromise the electrical performance of the submerged electrical devices, their cooling performance is inferior compared to ideal coolants such as water. To use water as an immersion coolant, the electronics need to be encapsulated to prevent short circuits. Here, a packaging approach is developed that insulates the electronics from the surrounding water and spreads heat for better cooling. The package consists of an aluminum nitride (AlN) component for insulation and heat spreading, and a Parylene C coating for conformal electrical insulation. The package is characterized electrically by measuring the leakage current in water under DC voltages up to 600 V for periods up to 7 days. The thermal performance of this packaging method is also characterized by calculating the junction-to-coolant thermal resistance. The developed packaging design can be implemented in high power density applications where the heat flux is beyond what standard dielectric fluids can handle. © 2011-2012 IEEE.

关键词： Dielectric liquids

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Performance Analysis of Infrastructure Sharing Techniques in Cellular Networks: A Percolation Theory Approach

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IEEE Transactions on Vehicular Technology 2025年

作者： Lin, Hao Kishk, Mustafa A. Alouini, Mohamed-Slim King Abdullah University of Science and Technology (KAUST) Electrical and Computer Engineering Program Computer Electrical and Mathematical Sciences and Engineering Division (CEMSE) Thuwal 23955-6900 Saudi Arabia Maynooth University Department of Electronic Engineering Maynooth W23 F2H6 Ireland King Abdullah University of Science and Technology (KAUST) CEMSE Division Thuwal 23955-6900 Saudi Arabia

In the context of 5G, infrastructure sharing has been identified as a potential solution to reduce the investment costs of cellular networks. In particular, it can help low-income regions build 5G networks more affordably and further bridge the digital divide. There are two main kinds of infrastructure sharing: passive sharing (i.e., site sharing) and active sharing (i.e., access sharing), which require mobile network operators (MNOs) to share their non-electronic elements or electronic elements, respectively. Because co-construction and sharing can achieve broader coverage with lower investment, through percolation theory, we investigate how different sharing strategies can deliver large-scale continuous services. First, we examine the percolation characteristics in signal-to-interference-plus-noise ratio (SINR) coverage graphs and the necessary conditions for percolation. Second, we propose an ‘average coverage radius’ to approximate the SINR graph with a low base station (BS) density based on the Gilbert disk model. Finally, we estimate the critical conditions of BS densities of MNOs for different sharing strategies and compare the percolation probabilities under different infrastructure sharing strategies. © 1967-2012 IEEE.

关键词： Gilbert disk model graph theory Infrastructure sharing percolation theory stochastic geometry

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