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A destructive electrical breakdown study of metal-oxide-semiconductor device under accumulation and pre-avalanche modes

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Physica Scripta 2025年第6期100卷

作者： Khaliq, Afshan Ali, Munir Salman, Ayesha Bozdar, Mateen Qadir, Akeel Huang, Shihua Department of Physics Zhejiang Normal University Jinhua 321004 China College of Information Science and Electronic Engineering Zhejiang University Zhejiang Hangzhou 310027 China School of Electronics and Computer Sciences Air University Islamabad 44230 Pakistan School of Information Engineering Xi’an Eurasia University 710065 China

A metal-oxide-semiconductor heterostructure is a prominent solid-state device used extensively in photo detection and logic operations. The insulating dielectric layer is crucial for the device’s performance. When operated under dynamic and high electric field conditions, leakage current due to Fowler-Nordheim tunneling in oxide, leads to high power consumption. The injection of hot carriers into oxide can create pin-holes and cause oxide breakdown, further degrading device characteristics. In this study, we tested the robustness of a metal-oxide-semiconductor device under dark conditions using fast ramp and sinusoidal gating signals. We analysed the accumulation, depletion, deep-depletion, and pre-avalanche states over various durations. This simple approach helps us determine the device’s safe operational limits by providing insights into the oxide and semiconductor breakdown processes. We discussed the amplitudes of displacement current against gating rates in accumulation and deep-depletion/pre-avalanche states, noting that symmetry loss at higher frequencies indicates oxide deterioration. This gating strategy is applicable to devices with either directly grown silicon dioxide or high-k oxides, making it suitable for applications like surveillance, adaptive optics, and LiDAR, where power dissipation management is crucial. © 2025 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.

关键词： accumulation deep-depletion displacement current dynamic gating metal-oxide-semiconductor pre-avalanche

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Interfacial strong coupling and negative dispersion of propagating polaritons in freestanding oxide membranes

arXiv

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arXiv 2025年

作者： Lukaskawcez, Brayden Varshney, Shivasheesh Choo, Sooho Park, Sang Hyun Seo, Dongjea Thompson, Liam Uram, Devon Binger, Hayden Koester, Steve Oh, Sang-Hyun Low, Tony Jalan, Bharat McLeod, Alexander School of Physics and Astronomy University of Minnesota Twin Cities MinneapolisMN55455 United States Department of Chemical Engineering and Materials Science University of Minnesota Twin Cities MinneapolisMN55455 United States Department of Electrical and Computer Engineering University of Minnesota MinneapolisMN55455 United States

Membranes of complex oxides like perovskite SrTiO3 extend the multi-functional promise of oxide electronics into the nanoscale regime of two-dimensional materials. Here we demonstrate that free-standing oxide membranes supply a reconfigurable platform for nano-photonics based on propagating surface phonon polaritons. We apply infrared near-field imaging and - spectroscopy enabled by a tunable ultrafast laser to study pristine nano-thick SrTiO3 membranes prepared by hybrid molecular beam epitaxy. As predicted by coupled mode theory, we find that strong coupling of interfacial polaritons realizes symmetric and antisymmetric hybridized modes with simultaneously tunable negative and positive group velocities. By resolving reflection of these propagating modes from membrane edges, defects, and substrate structures, we quantify their dispersion with position-resolved nano-spectroscopy. Remarkably, we find polariton negative dispersion is both robust and tunable through choice of membrane dielectric environment and thickness and propose a novel design for in-plane Veselago lensing harnessing this control. Our work lays the foundation for tunable transformation optics at the nanoscale using polaritons in a wide range of freestanding complex oxide membranes. © 2025, CC BY.

关键词： Perovskite

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High-Q unidirectional polarization singularities

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Physical Review Applied 2025年第5期23卷 054020-054020页

作者： Chuanlin Li Wenhao Wang Jianfeng Chen Mengqi Liu Aobo Ren Cheng-Wei Qiu Hongxing Xu Zhiming Wang Jiang Wu Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu 610054 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore Centre for Disruptive Photonic Technologies The Photonics Institute Nanyang Technological University Singapore 637371 Singapore Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore Institute of Engineering Thermophysics School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Physics and Technology Center for Nanoscience and Nanotechnology and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education Wuhan University Wuhan 430072 China

Unidirectional guided resonances (UGRs), which are eigenstates that radiate exclusively in a single channel, are promising for advancing diverse photonic devices. However, existing approaches face an inherent trade-off between achieving high-Q factors and maximizing the radiation-asymmetry ratios. To address this challenge, we propose a scheme that exploits both out-of-plane and in-plane couplings to generate bound states in the continuum with precise radial and rotational control in momentum space. This approach effectively decouples the Q factors of UGRs from their radiation-asymmetry ratios. As a result, we achieve UGRs with Q factors exceeding 104, which is 1–2 orders of magnitude higher than traditional UGRs. Furthermore, we demonstrate the ability to reverse the emission direction of these UGRs, leading to a broad range of radiation-asymmetry ratios from −53 to 55 dB. We further validate the practical realization of high-Q UGRs using a silicon-on-silica system. Our findings provide a versatile method for generating high-Q UGRs, offering alternative pathways for innovations in nonlinear optics, light-matter interactions, and advanced optoelectronic applications.

关键词： Nonlinear optics

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Changes in gait asymmetry may be caused by adaptation of spinal reflexes

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Journal of Neurophysiology 2025年第4期133卷 1208-1215页

作者： Refy, Omar Mo, Owen Weber, Douglas J. Geyer, Hartmut Physics Department Carnegie Mellon University Pittsburgh PA United States Mechanical Engineering Department Carnegie Mellon University Pittsburgh PA United States Robotics Institute Carnegie Mellon University Pittsburgh PA United States Neuroscience Institute Carnegie Mellon University Pittsburgh PA United States NeuroMechatronics Lab Carnegie Mellon University Pittsburgh PA United States Legged Systems Lab Carnegie Mellon University Pittsburgh PA United States School of Computer Science Carnegie Mellon University Pittsburgh PA United States

In a recent human study, we found that adaptive changes in step length asymmetry (SLA) are correlated with similar changes in the H-reflex gains of the leg muscles during split-belt treadmill locomotion. Although this observation indicated a closer link between gait asymmetry and spinal reflex adaptation, it did not reveal their causal relationship. To better understand this relationship, here we use a neuromuscular model of human walking whose control relies primarily on spinal reflexes. Subjecting the model to split-belt treadmill locomotion with different combinations of belt speed and reflex gain patterns, we find that belt speed changes increase the variability in SLA but do not result in consistent SLA patterns as observed in human experiments, whereas reflex gain changes do. Furthermore, we find that the model produces SLA patterns similar to healthy adults when its reflex gains are adapted in a way similar to the H-reflex changes we observed in our previous study. The model also predicts SLA patterns similar to the ones observed for cerebellar degeneration patients when the reflexes do not adapt beyond a sudden dip at the time the ipsilateral belt speed is lowered. Our results suggest that SLA does not arise from imposing belt speed changes but requires the change of the reflex gains and that the dynamic adjustment of these gains may be an essential part of human gait control when encountering unexpected environmental changes such as uneven speed changes in split-belt treadmill locomotion. NEW & NOTEWORTHY This work uses computational modeling to investigate the role of spinal reflex tuning during locomotor adaptation. We show, in simulation, that tuning spinal reflex gains leads to gait asymmetry adaptation, not vice versa, and that patterns of gait adaptation on a split-belt treadmill are mostly driven by tuning of spinal reflexes, and not by biomechanical disturbances triggered by belt changes. The model further hints at the cerebellum as the source of sp

关键词： computational modeling gait adaptation neuromuscular model spinal reflex split-belt

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Tracking relaxation dynamics of polaritons and reservoir states in organic exciton-polaritons

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The journal of physical chemistry letters 2025年 5265-5271页

作者： Haolin Chen Jingxuan Ai Xiaolu Bai Shaocong Hou Stephen R Forrest Jennifer P Ogilvie Yin Song MIIT Key Laboratory of Complex-Field Intelligent Exploration School of Optics and Photonics Beijing Institute of Technology Beijing 100081 China. School of Electrical Engineering and Automation Wuhan University Wuhan Hubei 430072 China. Department of Physics University of Michigan Ann Arbor Michigan 48109 United States. Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor Michigan 48109 United States. Department of Material Science and Engineering University of Michigan Ann Arbor Michigan 48109 United States. Department of Physics University of Ottawa Ottawa ON K1N 6N5 Canada.

Organic exciton-polaritons have garnered significant attention in optoelectronic devices and photochemistry, primarily due to their micrometer-scale diffusion lengths and tunable energy levels. Recent studies have underscored the critical role of reservoir states in the dynamical processes following polaritonic relaxation. However, questions remain regarding the peak assignments of reservoir states and their specific functions during relaxation. In this study, we employed pump-probe and two-dimensional electronic spectroscopy (2DES) coupled with model simulations to investigate photoexcited dynamics of organic exciton-polaritons. By comparing experimental data with simulations, we identified that reservoir states consist of dark states and excited-state molecules uncoupled to the cavity mode, each exhibiting distinct spectral characteristics. Analyses of the spectral evolution in 2DES reveal that reservoir states are generated through three pathways: direct photoexcitation, rapid relaxation from middle polaritons, and entropy-driven relaxation from lower polaritons. Moreover, we find that equilibrium is established between dark states and uncoupled excited-state molecules following polaritonic relaxation, regardless of the excitation wavelength. This equilibrium facilitates subsequent polaritonic regeneration. Modulating the equilibrium constant can be achieved by engineering the light-matter interaction strength, offering a strategy to control postrelaxation polaritonic dynamics. These insights advance our understanding of relaxation dynamics in organic exciton-polaritons that can benefit the design of next-generation optoelectronic devices.

关键词： Phototubes

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Efficient Angle Estimation in MIMO Radar With Limited Antenna Resources Via Rearranging Bayesian Tensor Analysis

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IEEE Transactions on Vehicular Technology 2025年

作者： Yu, Weijia Du, Jianhe Chen, Yuanzhi Zhang, Junwei Li, Xingwang Nallanathan, Arumugam Communication University of China State Key Laboratory of Media Convergence and Communication Beijing100024 China Henan Polytechnic University School of Physics and Electronic Information Engineering Henan Jiaozuo454150 China Queen Mary University of London School of Electronic Engineering and Computer Science London United Kingdom Kyung Hee University Department of Electronic Engineering Gyeonggi-do Yongin-si17104 Korea Republic of

In this letter, we investigate the angle estimation problem of multiple-input multiple-output (MIMO) radar with limited antenna resources. Considering the advantage of tensor structure, the received signal is constructed as a third-order complex-valued parallel factor (PARAFAC) model. Then, a Bayesian inference scheme combining tensor rearrangement and real-valued pre-processing is proposed, which obtains directions of departure (DoDs) and directions of arrival (DoAs) by fitting an optimized tensor model. The proposed scheme provides satisfactory angle estimation performance for the limited number of array antennas and the unknown number of targets. Simulation results demonstrate the robustness and effectiveness of the proposed scheme. © 1967-2012 IEEE.

关键词： Direction of arrival

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Joint high-resolution feature learning and vessel-shape aware convolutions for efficient vessel segmentation

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computers in Biology and Medicine 2025年 191卷 109982-109982页

作者： Zhang, Xiang Zhu, Qiang Hu, Tao Guo, Song Bian, Genqing Dong, Wei Hong, Rao Lin, Xia Ling Wu, Peng Zhou, Meili Yan, Qingsen Mohi-ud-din, Ghulam Ai, Chen Li, Zhou College of Information and Control Engineering Xi'an University of Architecture and Technology Xi'an China Shaanxi Provincial Key Lab of Bigdata of Energy and Intelligence Processing School of Physics and Electronic Information Yanan University Yanan China School of Computer Science and Engineering Northwestern Polytechnical University Xi'an China School of Software Nanchang University Nanchang China School of Cyber Security Zhejiang University Hangzhou China Department of Basic Education and Research Jiangxi Police College Nanchang China Northwestern Polytechnical University China

Clear imagery of retinal vessels is one of the critical shreds of evidence in specific disease diagnosis and evaluation, including sophisticated hierarchical topology and plentiful-and-intensive capillaries. In this work, we propose a new topology- and shape-aware model named Multi-branch Vessel-shaped Convolution Network (MVCN) to adaptively learn high-resolution representations from retinal vessel imagery and thereby capture high-quality topology and shape information thereon. Two steps are involved in our pipeline. The former step is proposed as Multiple High-resolution Ensemble Module (MHEM) to enhance high-resolution characteristics of retinal vessel imagery via fusing scale-invariant hierarchical topology thereof. The latter is a novel vessel-shaped convolution that captures the retinal vessel topology to emerge from unrelated fundus structures. Moreover, our MVCN of separating such topology from the fundus is a dynamical multiple sub-label generation via using epistemic uncertainty, instead of manually separating raw labels to distinguish definitive and uncertain vessels. Compared to other existing methods, our method achieves the most advanced AUC values of 98.31%, 98.80%, 98.83%, and 98.65%, and the most advanced ACC of 95.83%, 96.82%, 97.09%,and 96.66% in DRIVE, CHASE_DB1, STARE, and HRF datasets. We also employ correctness, completeness, and quality metrics to evaluate skeletal similarity. Our method's evaluation metrics have doubled compared to previous methods, thereby demonstrating the effectiveness thereof. © 2025 Elsevier Ltd

关键词： Ophthalmology

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Secure Precoding Design for RSMA Transmission in HAP-Assisted Non-Terrestrial Networks

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IEEE Transactions on Vehicular Technology 2025年

作者： Huang, Mengyan Gong, Fengkui Zhao, Jiahui Yin, Zhisheng Li, Xingwang Pham, Quoc-Viet Xidian University State Key Laboratory of Integrated Services Networks Xi'an710071 China Trinity College Dublin School of Computer Science and Statistics D02 PN40 Ireland Southeast University National Mobile Communications Research Laboratory Nanjing210096 China Henan Polytechnic University School of Physics and Electronic Information Engineering Jiaozuo China

The non-terrestrial networks (NTNs) are recognized as a key component to provide cost-effective and high-capacity ubiquitous connectivity in the future wireless communications. To improve the spectral efficiency in NTNs, rate-splitting multiple access (RSMA) has attracted considerable attention. Nevertheless, the major issue of the considered system is to overcome security hurdles. In this paper, a robust secure precoding transmission scheme based on RSMA is proposed, which is the first time being used for high-altitude platform (HAP)- assisted satellite NTNs. The system features a low-earth orbit satellite that serves multiple ground user equipments (GUEs) using a rate-splitting strategy, while a decode-and-forward HAP relay assists the satellite in establishing communication links with the GUEs. Assuming imperfect channel state information, we formulate an optimization problem to maximize the sum secrecy rate (SSR) of GUEs. The problem jointly optimizes the precoding vectors for both the satellite and the HAP relay, subject to constraints on their maximum transmit powers and the achievable secrecy rates for each GUE. Subsequently, leveraging successive convex approximation and semidefinite relaxation, we present an approach to transform the non-convex constraints into convex ones, enabling the precoding vectors to be obtained through an iterative procedure. Simulation results show that the RSMA can achieve SSR of up to 3.25 bps/Hz and 3.75 bps/Hz compared to non-orthogonal multiple access and time division multiple access, respectively © 1967-2012 IEEE.

关键词： Satellite links

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Efficient on-chip green light generation via frequency upconversion in SiN–transfer-printed LN hybrid waveguides

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Optics Letters 2025年第10期50卷 3281-3284页

作者： Sumon, Md. Saiful Islam Vorobev, Artem S. Ghosh, Samir Atar, Fatih Bilge Maraviglia, Nicola Nikor, Sk. Shafaat Saud Devarapu, Ganga Chinna Rao Maddi, Chiranjeevi Faruque, Imad I. Dwivedi, Sarvagya Bowman, Robert O’Faolain, Liam Corbett, Brian Arafin, Shamsul Department of Electrical and Computer Engineering The Ohio State University ColumbusOH43210 United States Centre for Advanced Photonics and Process Analysis Munster Technological University Bishopstown CorkT12 T66T Ireland Tyndall National Institute University College Cork Lee Maltings Complex Dyke Parade T12 R5CP Cork Ireland School of Mathematics and Physics Queen’s University Belfast BelfastBT7 1NN United Kingdom School of Mathematical and Physical Science University of Sheffield SheffieldS3 7RH United Kingdom Kilby Labs Texas Instruments DallasTX75243 United States

We demonstrate efficient on-chip green light generation via frequency upconversion in silicon nitride–thin-film lithium niobate (SiN-TFLN) hybrid waveguides, obtained by transfer printing LN coupons on selected areas of photonic integrated circuits (PICs). By utilizing modal phase matching (MPM), our devices achieve a high normalized conversion efficiency of 42.5% W−1cm−2 in a single-pass, 2.4-mm-long waveguide configuration. The SiN–LN transition in the waveguide inherently facilitates mode conversion, transforming a higher-order second-harmonic mode into a fundamental TE mode, ensuring coherent, narrow-linewidth, green light emission. Our waveguide platform gives rise to a wavelength shift of ∼1 nm for every 10 nm of waveguide width variation and temperature-induced wavelength tuning of ∼0.02 nm/°C. © 2025 Optica Publishing Group. All rights are reserved.

关键词： Photonic integrated circuits

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Photo-luminescence properties of ion implanted Er3+-defects in 4H-SiCOI towards integrated quantum photonics

arXiv

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arXiv 2025年

作者： Bader, Joshua Lim, Shao Qi Inam, Faraz Ahmed Johnson, Brett C. Peruzzo, Alberto McCallum, Jeffrey Li, Qing Castelletto, Stefania School of Engineering RMIT University MelbourneVIC3000 Australia Quantum Photonics Laboratory Centre for Quantum Computation and Communication Technology School of Engineering RMIT University MelbourneVIC3000 Australia Centre for Quantum Computation and Communication Technology School of Physics The University of Melbourne MelbourneVIC3010 Australia Department of Physics Aligarh Muslim University Aligarh202002 India School of Science RMIT University Melbourne3001 Australia Advanced Research Department Qubit Pharmaceuticals Paris75014 France Electrical and Computer Engineering Carnegie Mellon University PittsburghPA15213 United States

Colour centres hosted in solid-state materials such as silicon carbide and diamond are promising candidates for integration into chip-scale quantum systems. Specifically, the incorporation of these colour centres within photonic integrated circuits may enable precise control over their inherent photo-physical properties through strong light-matter interaction. Here, we investigate ion-implanted erbium (Er3+) defects embedded in thin-film 4H-silicon-carbide-on-insulator (4H-SiCOI). Optimized implantation conditions and thermal annealing processes designed to enhance the emission characteristics of the Er3+-defect are reported. By examining key properties such as photoluminescence intensity, optical lifetime, and polarization, we present an analysis of ensemble Er3+-defects within 4H-SiCOI, providing insights into their potential for future quantum applications. © 2025, CC0.

关键词： Nanocrystals

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