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arXiv 2025年

作者： Chen, Yu-Hsin Encomendero, Jimy Xing, Huili Grace Jena, Debdeep Department of Materials Science and Engineering Cornell University IthacaNY14853 United States School of Electrical and Computer Engineering Cornell University IthacaNY14853 United States Kavli Institute Cornell for Nanoscale Science Cornell University IthacaNY14853 United States

We report the observation of Shubnikov-de Haas (SdH) oscillations in coherently strained, low-dislocation AlN/GaN/AlN quantum wells (QWs), including both undoped and δ-doped structures. SdH measurements reveal a single subband occupation in the undoped GaN QW and two subband occupation in the δ-doped GaN QW. More importantly, SdH oscillations enable direct measurement of critical two-dimensional electron gas (2DEG) parameters at the Fermi level: carrier density and ground state energy level, electron effective mass (m∗ ≈ 0.289 me for undoped GaN QW and m∗ ≈ 0.298 me for δ-doped GaN QW), and quantum scattering time (τq ≈ 83.4 fs for undoped GaN QW and τq ≈ 130.6 fs for δ-doped GaN QW). These findings provide important insights into the fundamental properties of 2DEGs that are strongly quantum confined in the thin GaN QWs, essential for designing nitride heterostructures for high-performance electronic applications. © 2025, CC BY-NC-ND.

关键词： Gallium nitride

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A plasmon-electron addressable and CMOS compatible random access memory

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science Advances 2025年第19期11卷 eadr1172页

作者： Greig, Shawn R. Firby, Curtis J. Muneshwar, Triratna Alagöz, Serhat Hopmann, Eric Carnio, Brett N. Zhang, Mingyuan Ciarniello, Grace Cadien, Kenneth Elezzabi, Abdulhakem Y. Department of Electrical and Computer Engineering University of Alberta EdmontonT6G 2V4 Canada Department of Metallurgical Engineering and Materials Science Indian Institute of Technology Bombay400-076 India Department of Physics University of Alberta EdmontonT6G 2E1 Canada Department of Chemical and Materials Engineering University of Alberta EdmontonABT6G 2V4 Canada

The rapid increase in data generation and storage poses substantial challenges, necessitating a transition from traditional charge-based devices to high-speed optical alternatives for computational tasks. Photon-assisted or plasmon-assisted memory devices emerge as promising solutions for facilitating faster read/write operations. By using surface plasmon polaritons for writing operations, we can dynamically read memory states through the measurement of tunneling currents in thin layers of HfO2 ferroelectric materials sandwiched between Au thin film electrodes. Our plasmon-addressable memory platform offers versatile functionality in both nanoelectronic and nanoplasmonic systems, demonstrating a robust hybrid architecture with transformative potential for computing and data processing applications. Copyright © 2025 The Authors, some rights reserved.

关键词： Ferroelectric materials

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Vertical p-GaN/n-Ga2O3 heterojunction diodes enabled by PAMBE

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Applied Physics Letters 2025年第17期126卷

作者： Kelly, Frank P. Landi, Matthew M. Kim, Kyekyoon Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Department of Materials Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Holonyak Micro and Nanotechnology Laboratory University of Illinois at Urbana-Champaign UrbanaIL61801 United States

Vertical diodes are produced via the nitridation of (-201) β-Ga2O3 and subsequent GaN epitaxy via PAMBE. For undoped films, the mosaic block model parameters are extracted via XRD and used to calculate dislocation densities, where optimization of the nitridation and growth enabled two orders of magnitude reduction in screw dislocation density. These results validate a model relating screw dislocation formation to initial edge dislocation densities. The dislocation densities are compared to device parameters extracted from vertical Schottky barrier diodes on the same samples. The current on/off ratio, ideality, and Schottky barrier height are found to depend on screw dislocation density, edge dislocation density, and surface roughness, respectively. The Mg-dopant activation energy was measured to be 160 meV. Diode on/off ratios range between 10 4 and 10 5 with a differential specific on-resistance of 2.4 m Ω cm2 and a forward current density >1 kA/cm2 measured prior to reaching compliance. Temperature dependent I-V measurements are conducted to investigate reverse-bias leakage current, and variable-range hopping is identified as the transport mechanism. The hopping conduction follows a 3D mode at moderate temperatures, but above 100 °C transitions to a 1D mode. © 2025 Author(s).

关键词： Schottky barrier diodes

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Impact of Quantum Well Thickness on Efficiency Loss in InGaN/GaN LEDs: Challenges for Thin-Well Designs

arXiv

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arXiv 2025年

作者： Li, Xuefeng Pant, Nick Rahman, Sheikh Ifatur Armitage, Rob Rajan, Siddharth Kioupakis, Emmanouil Feezell, Daniel University of New Mexico AlbuquerqueNM87106 United States Department of Materials Science & Engineering University of Michigan Ann ArborMI48109 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Electrical and Computer Engineering The Ohio State University ColumbusOH43210 United States Lumileds LLC San JoseCA95131 United States Department of Materials Science and Engineering The Ohio State University ColumbusOH43210 United States

We investigate the impact of quantum well (QW) thickness on efficiency loss in c-plane InGaN/GaN LEDs using a small-signal electroluminescence (SSEL) technique. Multiple mechanisms related to efficiency loss are independently examined, including injection efficiency, carrier density vs. current density relationship, phase space filling (PSF), quantum confined stark effect (QCSE), and Coulomb enhancement. An optimal QW thickness of around 2.7 nm in these InGaN/GaN LEDs was determined for quantum wells having constant In composition. Despite better control of deep-level defects and lower carrier density at a given current density, LEDs with thin QWs still suffer from an imbalance of enhancement effects on the radiative and intrinsic Auger-Meitner recombination coefficients. The imbalance of enhancement effects results in a decline in internal quantum efficiency (IQE) and radiative efficiency with decreasing QW thickness at low current density in LEDs with QW thicknesses below 2.7 nm. We also investigate how LED modulation bandwidth varies with quantum well thickness, identifying the key trends and their implications for device performance. Copyright © 2025, The Authors. All rights reserved.

关键词： Semiconductor quantum wells

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Metal-organic chemical vapor deposition of MgSiN2 thin films

arXiv

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arXiv 2025年

作者： Vangipuram, Vijay Gopal Thirupakuzi Hu, Chenxi Majumder, Abdul Mukit Chae, Christopher Zhang, Kaitian Hwang, Jinwoo Kash, Kathleen Zhao, Hongping Department of Electrical and Computer Engineering The Ohio State University ColumbusOH43210 United States Department of Physics Case Western Reserve University ClevelandOH44106 United States Department of Materials Science and Engineering The Ohio State University ColumbusOH43210 United States

Orthorhombic-structured II-IV nitrides provide a promising opportunity to expand the material platform while maintaining compatibility with the wurtzite crystal structure of the traditional III-nitride material system. Among them, MgSiN2 stands out due to its close compatibility with GaN and AlN and its theoretically predicted ultrawide direct band gap of 6.28 eV. In this work, the growth of MgSiN2 thin films on GaN-on-sapphire and c-plane sapphire substrates was investigated using metal-organic chemical vapor deposition (MOCVD). MOCVD growth conditions were correlated with film quality and crystallinity for samples grown on GaN-on-sapphire substrates. The effects of Mg:Si precursor molar flow rate ratios and growth pressure at two different temperatures, 745℃ and 850℃, were studied comprehensively. High-resolution scanning transmission electron microscopy (STEM) imaging confirmed the formation of high-quality, single-crystal MgSiN2 films. Optical band gap extraction from transmittance measurements yielded direct band gap values ranging from 6.13 eV to 6.27 eV for samples grown under various conditions, confirming the realization of an ultrawide-band gap, III-nitride-compatible, II-IV-nitride material. Copyright © 2025, The Authors. All rights reserved.

关键词： Sapphire

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Joint Source Decomposition of Concurrent EEG-FMRI Data in Epilepsy and Control Groups

Joint Source Decomposition of Concurrent EEG-FMRI Data in Ep...

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IEEE International Symposium on Biomedical Imaging

作者： J. Mason Harding Haatef Pourmotabbed Yamin Li Kimberly Rogge-Obando Kate Wang Sarah E. Goodale Shiyu Wang Camden Bibro Bergen Allee Caroline Martin Victoria L. Morgan Dario J. Englot Catie Chang Department of Electrical and Computer Engineering Vanderbilt University Department of Biomedical Engineering Vanderbilt University Department of Computer Science Vanderbilt University Neuroscience Graduate Program Vanderbilt University Vanderbilt Memory and Alzheimer's Center Vanderbilt University Medical Center Department of Neurological Surgery Vanderbilt University Medical Center Department of Radiology Vanderbilt University Medical Center

ISBN: (数字)9798331520526

ISBN: (纸本)9798331520533

EEG and fMRI are complementary, noninvasive technologies for investigating human brain function. These modalities have been used to uncover large-scale functional networks and their disruptions in clinical populations. Given the high temporal resolution of EEG and high spatial resolution of fMRI, integrating these modalities can provide a more holistic understanding of brain activity. This work explores a multimodal source decomposition technique for extracting shared modes of temporal variation between fMRI BOLD signals and EEG spectral power fluctuations in the resting state. The resulting components are then compared between patients with focal epilepsy and controls, revealing multimodal network differences between groups.

关键词： Neuroimaging Brain Fluctuations Epilepsy Functional magnetic resonance imaging Electroencephalography Pattern recognition Hemodynamics Spatial resolution Signal resolution

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AI-guided frame prediction techniques to model single crystal diamond growth

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Journal of Vacuum science and Technology A: Vacuum, Surfaces and Films 2025年第3期43卷

作者： Mekala, Rohan Reddy Srinivasan, Arjun Muehle, Matthias Garratt, Elias Porter, Adam Lindvall, Mikael College ParkMD United States College ParkMD United States Department of Electrical and Computer Engineering Department of Materials Science and Chemical Engineering Michigan State University College ParkMD United States Department of Computer Science University of Maryland College ParkMD United States

Single-crystal diamond (SCD) is an attractive wide bandgap semiconductor material for a variety of applications. While lab-scale prototype demonstrations have demonstrated superior performance, utilizing diamond has been prohibitively expensive compared to more mature, commercialized semiconductor materials. The only way to overcome this is by controlling the size and quality of SCD wafers during chemical vapor deposition. We are addressing this challenge by using an artificial intelligence (AI)-based algorithm to predict SCD growth states through the use of in situ red, green, blue (RGB) images. This AI growth prediction can be incorporated as the control system to increase the SCD wafer size and quality. First, we installed a full-frame mirrorless interchangeable lens camera equipped with a macrolens to a diamond synthesis reactor. Then, a cumulative AI-based pipeline comprising three distinct and interconnected components was developed to model and guide diamond growth: (1) A feature extraction pipeline, using deep learning-based semantic segmentation models to isolate and quantify geometric growth features such as diamond contours and pocket holder regions from in situ RGB images. (2) A defect detection pipeline, employing object detection and segmentation architectures to identify and localize macroscopic defects, including polycrystalline growth and edge anomalies, during the growth process. (3) A frame prediction pipeline, which combines image sequences and reactor telemetry using a generative deep learning architecture to forecast future reactor states, including expected growth morphology and potential defect emergence. Prediction accuracies of greater than ∼99% were obtained with minimal information loss between predicted and actual outputs. This constitutes a never-before obtained result of spatiotemporal (AI) prediction of diamond shape from in situ growth data. This demonstrates the potential of these algorithms as a machine-intelligence-enabled solutio

关键词： Semantic Segmentation

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Thermal Annealing and Radiation Effects on Structural and electrical Properties of NbN/GaN Superconductor/Semiconductor Junction

arXiv

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arXiv 2025年

作者： Margiotta, Stephen Liu, Binzhi Khan, Saleh Ahmed Ortiz, Gabriel Calderon Ibreljic, Ahmed Hwang, Jinwoo Bhuiyan, A.F.M. Anhar Uddin Department of Electrical and Computer Engineering University of Massachusetts Lowell LowellMA01854 United States Lincoln Laboratory Massachusetts Institute of Technology LexingtonMA02421 United States Department of Materials Science and Engineering The Ohio State University ColumbusOH43210 United States

In the rapidly evolving field of quantum computing, niobium nitride (NbN) superconductors have emerged as integral components due to their unique structural properties, including a high superconducting transition temperature, exceptional electrical conductivity, and compatibility with advanced device architectures. This study investigates the impact of high temperature annealing and high dose gamma irradiation on the structural, electrical and superconducting properties of NbN films grown on GaN via reactive DC magnetron sputtering. The as-deposited cubic δ-NbN (111) films exhibited high intensity distinct x-ray diffraction (XRD) peak, a high superconducting transition temperature (Tc) of 12.82 K, and an atomically flat surface. Annealing at 500 °C and 950 °C for varying durations revealed notable structural and surface changes. High resolution scanning transmission electron microscopy (STEM) indicated improved local ordering, while atomic force microscopy (AFM) showed reduced surface roughness after annealing. X-ray photoelectron spectroscopy (XPS) revealed a gradual increase in the Nb/N ratio with higher annealing temperatures and durations. High-resolution XRD and STEM analysis showed lattice constant modifications in δ-NbN films, attributed to residual stress changes following annealing. Additionally, XRD φ-scans revealed sixfold symmetry in NbN films due to rotational domains relative to GaN. While Tc remained stable after annealing at 500 °C, increasing the annealing temperature to 950 °C degraded Tc to ~8 K and reduced the residual resistivity ratio (RRR) from 0.85 in as-deposited films to 0.29 after 30 minutes. The effects of high-dose gamma radiation (5 Mrad (Si)) were also studied, demonstrating minimal changes to crystallinity and superconducting performance, indicating excellent radiation resilience. These findings highlight the potential of NbN superconductors for integration into advanced quantum devices and its suitability for applications in radiatio

关键词： Gallium nitride

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Low-phase-noise surface-acoustic-wave oscillator using an edge mode of a phononic band gap

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Physical Review Applied 2025年第2期23卷 024054-024054页

作者： Zichen Xi Joseph G. Thomas Jun Ji Dongyao Wang Zengyu Cen Ivan I. Kravchenko Bernadeta R. Srijanto Yu Yao Yizheng Zhu Bradley Department of Electrical and Computer Engineering Virginia Tech Blacksburg Virginia 24061 USA Center for Quantum Information Science and Engineering (VTQ) Virginia Tech Blacksburg Virginia 24061 USA Center for Photonics Technology Virginia Tech Blacksburg Virginia 24061 USA School of Electrical Computer and Energy Engineering Arizona State University Tempe Arizona 85281 USA Center for Photonic Innovation Arizona State University Tempe Arizona 85281 USA Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge Tennessee 37830 USA

Low-phase-noise microwave-frequency integrated oscillators provide compact solutions for various applications in signal processing, communications, and sensing. Surface acoustic waves (SAWs), featuring orders-of-magnitude shorter wavelength than electromagnetic waves at the same frequency, enable integrated microwave-frequency systems with much smaller footprint on chip. SAW devices also allow higher-quality (Q) factors than electronic components at room temperature. Here, we demonstrate a low-phase-noise gigahertz-frequency SAW oscillator on 128°Y-cut lithium niobate, where the SAW resonator occupies a footprint of 0.05mm2. Leveraging phononic crystal band-gap-edge modes to balance between Q factors and insertion losses, our 1-GHz SAW oscillator features a low phase noise of −132.5 dBc/Hz at a 10-kHz offset frequency and an overlapping Hadamard deviation of 6.5 × 10−10 at an analysis time of 64 ms. The SAW resonator-based oscillator holds high potential in developing low-noise sensors and acousto-optic integrated circuits.

关键词： Microwave oscillators

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Large-Scale Distributed Multidisciplinary Design Optimization of the NASA Lift-Plus-Cruise Air Taxi Concept

Large-Scale Distributed Multidisciplinary Design Optimizatio...

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AIAA science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： van Schie, Sebastiaan P. C. Ruh, Marius L. Fletcher, Andrew Warner, Michael Sperry, Mark Scotzniovsky, Luca Orndorff, Nicholas C. Xiang, Ru Yan, Jiayao Zhao, Han Krokowski, Joshua J. Chen, J.S. Sarojini, Darshan Gill, Hyunjune Lee, Seongkyu Tagg, Andrew Anderson, Ryan Green, Eric Joseph, Cibin Ning, Andrew Cheng, Zeyu Cao, Zhi Mi, Chunting Guibert, Alexandre T. R. Cronk, Ashley Kim, H. Alicia Meng, Y. Shirley Silva, Christopher Hwang, John T. University of California San Diego 9500 Gilman Dr La Jolla CA92093 United States Department of Mechanical and Aerospace Engineering University of California San Diego 9500 Gilman Dr La Jolla CA92093 United States Department of Structural Engineering University of California San Diego 9500 Gilman Dr La Jolla CA92093 United States Aerospace and Ocean Engineering Department Virginia Tech 1600 Innovation Dr BlacksburgVA24060 United States Department of Mechanical and Aerospace Engineering University of California Davis 1 Shields Avenue DavisCA95616 United States Mechanical Engineering Brigham Young University ProvoUT84602 United States Department of Electrical & Computer Engineering San Diego State University 5500 Campanile Dr San Diego92182 United States Structural Engineering Department University of California San Diego 9500 Gilman Dr La Jolla CA92093 United States Materials Science & Engineering Program University of California San Diego 9500 Gilman Dr La Jolla CA92093 United States Pritzker School of Molecular Engineering The University of Chicago ChicagoIL60607 United States NASA Ames Research Center Moffett FieldCA94035 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

Large-scale gradient-based Multidisciplinary Design Optimization (MDO) can aid in the exploration of high-dimensional design spaces for novel air vehicle concepts, thereby leading to more efficient and economic designs. This paper builds on past works where we demonstrated large-scale physics-based MDO capabilities and applied these to NASA’s lift-plus-cruise electric air taxi concept. We extend this comprehensive mid-fidelity system-level optimization problem with high(er)-fidelity subsystem-level optimizations of various aircraft systems and mission phases, with the aim of further enhancing the accuracy and scope of the aforementioned system-level optimization problem: 1) Power minimization during the transition mission phase;2) electrical powertrain topology optimization;3) Cell chemistry modeling and thermomechanical battery pack topology optimization;4) Shell-based coupled aero-elastic wing structure optimization. An Analytical Target Cascading-like distributed MDO architecture allows us to couple the system- and subsystem-level optimizations in order to arrive at a consistent and feasible design. We find that the system-level design is most heavily impacted by the reduced battery pack-level energy densities that stem from power peaks in the mission profile. These power peaks seem to result from the inefficient lift rotor blade designs that are needed to satisfy noise constraints. We draw conclusions based on trends in our results and give recommendations for future MDO studies of electrical air taxi vehicle concepts. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Shape optimization

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