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Influence of mechanical compliance of the substrate on the morphology of nanoporous gold thin films

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arXiv 2024年

作者： Shahriar, Sadi Somayajula, Kavya Winkeljohn, Conner Mason, Jeremy Seker, Erkin Department of Materials Science and Engineering University of California - Davis DavisCA95616 United States Department of Mechanical and Aerospace Engineering University of California - Davis DavisCA95616 United States Department of Electrical and Computer Engineering University of California - Davis DavisCA95616 United States

Nanoporous gold (np-Au) has found use in applications ranging from catalysis to biosensing where pore morphology plays a critical role in performance. While morphology evolution of bulk np-Au has been widely studied, knowledge about its thin film form is limited. This work hypothesizes that mechanical compliance of the thin film substrate can play a critical role in the morphology evolution. Via experimental and finite-element-analysis approaches, we investigate the morphological variation in np-Au thin films deposited on compliant silicone (PDMS) substrates of a range of thicknesses anchored on rigid glass supports and compare those to the morphology of np-Au deposited on glass. More macroscopic (10s to 100s of microns) cracks and discrete islands form in the np-Au films on PDMS compared to glass. Conversely, uniformly-distributed microscopic (100s of nanometers) cracks form in greater numbers in the np-Au films on glass than on PDMS, with the cracks located within the discrete islands. The np-Au films on glass also show larger ligament and pore sizes possibly due to higher residual stresses compared to the np-Au/PDMS films. The effective elastic modulus of the substrate layers decreases with increasing PDMS thickness, resulting in secondary np-Au morphology effects including a reduction in macroscopic crack-to-crack distance, an increase in microscopic crack coverage, and a widening of the microscopic cracks. However, changes in the ligament/pore widths with PDMS thickness are negligible, allowing for independent optimization for cracking. We expect these results to inform the integration of functional np-Au films on compliant substrates into emerging applications, including flexible electronics. © 2024, CC BY-NC-SA.

关键词： Porous materials

Quantum Receiver Enhanced by Adaptive Learning

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Quantum Receiver Enhanced by Adaptive Learning

Conference on Lasers and Electro-Optics (CLEO)

作者： Chaohan Cui William Horrocks Saikat Guha N. Peyghambarian Quntao Zhuang Zheshen Zhang James C. Wyant College of Optical Sciences The University of Arizona Tucson Arizona USA Department of Electrical and Computer Engineering The University of Arizona Tucson Arizona USA Department of Materials Science and Engineering The University of Arizona Tucson Arizona USA

Adaptive quantum receiver designed by machine learning is demonstrated for discriminating multiple nonorthogonal coherent states, achieving reduced error rates of 20% (50%) over existing quantum (classical) receivers.... 详细信息

ISBN: (数字)9781957171050

ISBN: (纸本)9781665466660

关键词： Adaptive learning Error analysis Receivers Machine learning Lasers and electrooptics Electrooptical waveguides

Compressive phase space tomography

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Compressive phase space tomography

Frontiers in Optics, FIO 2013

作者： Barbastathis, George Tian, Lei Petruccelli, Jonathan C. Zhang, Zhengyun Rehman, Shakil Lee, Justin W. Pan, Adam Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA United States Singapore-MIT Alliance for Research and Technology Centre Massachusetts Institute of Technology Singapore UM-SJTU Joint Institute Shanghai Jiaotong University Shanghai China Department of Electrical Engineering and Computer Science University of California at Berkeley Berkeley CA United States Department of Physics State University of New York at Albany Albany NY United States Program in health Sciences and Technology Massachusetts Institute of Technology Cambridge MA United States

We present compressive sensing techniques to overcome the challenge of sampling the fourdimensional (4D) mutual intensity function, thus recovering complete information about the second-order statistical properties of... 详细信息

ISBN: (纸本)9781557529879

关键词： Compressed sensing

Clocked magnetostriction-assisted spintronic device design and simulation

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arXiv 2017年

作者： Iraei, .Rouhollah Mousavi Kani, Nickvash Dutta, Sourav Nikonov, Dmitri E. Manipatruni, Sasikanth Young, Ian A. Heron, John T. Naeemi, Azad Department of Electrical Computer Engineering Georgia Institute of Technology AtlantaGA United States Components Research Group Intel Corporation HillsboroOR United States Department of Materials Science and Engineering University of Michigan Ann ArborMI United States

We propose a heterostructure device comprised of magnets and piezoelectrics that significantly improves the delay and the energy dissipation of an all-spin logic (ASL) device. This paper studies and models the physics of the device, illustrates its operation, and benchmarks its performance using SPICE simulations. We show that the proposed device maintains low-voltage operation, non-reciprocity, non-volatility, cascadability, and thermal reliability of the original ASL device. Moreover, by utilizing the deterministic switching of a magnet from the saddle point of the energy profile, the device is more efficient in terms of energy and delay and is robust to thermal fluctuations. The results of simulations show that compared to ASL devices, the proposed device achieves 21' shorter delay and 27' lower energy dissipation per bit for a 32-bit arithmetic-logic unit (ALU). Copyright © 2017, The Authors. All rights reserved.

关键词： Magnets

Efficient Spin-Orbit Torques in an Antiferromagnetic Insulator with Tilted Easy Plane

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arXiv 2022年

作者： Zhang, Pengxiang Chou, Chung-Tao Yun, Hwanhui McGoldrick, Brooke C. Hou, Justin T. Mkhoyan, K. Andre Liu, Luqiao Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Chemical Engineering and Materials Science University of Minnesota MinneapolisMN55455 United States

electrical manipulation of spin textures inside antiferromagnets represents a new opportunity for developing spintronics with superior speed and high device density. Injecting spin currents into antiferromagnets and realizing efficient spin-orbit-torque-induced switching is however still challenging due to the complicated interactions from different sublattices. Meanwhile, because of the diminishing magnetic susceptibility, the nature and the magnitude of current-induced magnetic dynamics remain poorly characterized in antiferromagnets, whereas spurious effects further complicate experimental interpretations. In this work, by growing a thin film antiferromagnetic insulator, α-Fe2O3, along its non-basal plane orientation, we realize a configuration where an injected spin current can robustly rotate the Neel vector within the tilted easy plane, with an efficiency comparable to that of classical ferromagnets. The spin-orbit torque effect stands out among other competing mechanisms and leads to clear switching dynamics. Thanks to this new mechanism, in contrast to the usually employed orthogonal switching geometry, we achieve bipolar antiferromagnetic switching by applying positive and negative currents along the same channel, a geometry that is more practical for device applications. By enabling efficient spinorbit torque control on the antiferromagnetic ordering, the tilted easy plane geometry introduces a new platform for quantitatively understanding switching and oscillation dynamics in antiferromagnets. Copyright © 2022, The Authors. All rights reserved.

关键词： Switching

Electrochemical hydrogen charging treatment for hydrogenated 316 L stainless steel induced hydrogen therapy for orthopedic implantation

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Surface and Coatings Technology 2024年 479卷

作者： Lin, Yu-Chien Dhawan, Udesh Liu, Yen-Chen Lee, Yueh-Lien Liu, Xinke Yen, Hung-Wei Hu, Chih-Chien Chung, Ren-Jei Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei Taiwan School of Materials Science and Engineering Nanyang Technological University Singapore Centre for the Cellular Microenvironment Division of Biomedical Engineering James Watt School of Engineering Mazumdar-Shaw Advanced Research Centre University of Glasgow Glasgow United Kingdom Department of Engineering Science and Ocean Engineering National Taiwan University Taipei Taiwan College of Materials Science and Engineering Chinese Engineering and Research Institute of Microelectronics Shenzhen University Shenzhe China Department of Electrical and Computer Engineering National University of Singapore Singapore Department of Materials Science and Engineering National Taiwan University Taipei Taiwan Bone and Joint Research Center Chang Gung Memorial Hospital Linko Taiwan Department of Orthopaedic Surgery Chang Gung Memorial Hospital Linko Taiwan College of Medicine Chang Gung University Taoyuan Taiwan Taipei Taiwan

Post-implant inflammation is a leading factor in the failure of orthopedic implant surgery. Hydrogen therapy is viewed as a medium capable of reducing reactive oxygen species (ROS) to alleviate inflammatory responses. However, existing hydrogen therapy methods have limitations, often involving undesired inhalation, injection, or non-targeted exposure of hydrogen to the body. To address this, the concept of delivering hydrogen precisely using the implant itself has been conducted in this study. Traditional hydrogen treatments for metallic implant materials, such as 316 L stainless steel (316 L SS), can induce hydrogen embrittlement (HE), significantly restricting the potential applications of hydrogenated implants in the biomedical field. Therefore, in this study, the electrochemical cathodic hydrogen charging method was employed to diffuse a hydrogenated layer of approximately 216 ± 31 nm on the surface of 316 L SS. This renders the material minimized by HE and alters its surface properties. Through in vitro and in vivo experiments, an approximately 80 % free radical scavenging rate was achieved. Additionally, significant anti-inflammatory effects were observed in the histological analysis of Femur implantation. This demonstrates that the surface hydrogenation treatment can impart anti-inflammatory properties to metallic implant materials without compromising their inherent material properties, thereby enhancing the success rate of surgical procedures. © 2024

关键词： Hydrogen

Low frequency carrier kinetics in perovskite solar cells

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arXiv 2019年

作者： Sangwan, Vinod K. Zhu, Menghua Clark, Sarah Luck, Kyle A. Marks, Tobin J. Kanatzidis, Mercouri G. Hersam, Mark C. Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Wuhan430074 China Department of Chemistry Northwestern University EvanstonIL60208 United States Department of Electrical Engineering and Computer Science Northwestern University EvanstonIL60208 United States

Hybrid organic-inorganic halide perovskite solar cells have emerged as leading candidates for third-generation photovoltaic technology. Despite the rapid improvement in power conversion efficiency (PCE) for perovskite solar cells in recent years, the low frequency carrier kinetics that underlie practical roadblocks such as hysteresis and degradation remain relatively poorly understood. In an effort to bridge this knowledge gap, we perform here correlated low frequency noise (LFN) and impedance spectroscopy (IS) characterization that elucidates carrier kinetics in operating perovskite solar cells. Specifically, we focus on planar cell geometries with a SnO2electron transport layer and two different hole transport layers - namely, poly(triarylamine) (PTAA) and Spiro-OMeTAD. PTAA and Sprio-OMeTAD cells with moderate PCEs of 5 - 12% possess a Lorentzian feature at ~200 Hz in LFN measurements that corresponds to a crossover from electrode to dielectric polarization. In comparison, Spiro-OMeTAD cells with high PCEs (>15%) show four orders of magnitude lower LFN amplitude and are accompanied by a cyclostationary process. Through a systematic study of more than a dozen solar cells, we establish a correlation with noise amplitude, power conversion efficiency, and fill factor. Overall, this work establishes correlated LFN and IS as an effective methodology for quantifying low frequency carrier kinetics in perovskite solar cells, thereby providing new physical insights that can rationally guide ongoing efforts to improve device performance, reproducibility, and stability. Copyright © 2019, The Authors. All rights reserved.

关键词： Perovskite solar cells

Mechanisms of Ultrafast Charge Separation in a PTB7/Monolayer MoS2 van der Waals Heterojunction

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arXiv 2018年

作者： Zhong, Chengmei Sangwan, Vinod K. Wang, Chen Bergeron, Hadallia Hersam, Mark C. Weiss, Emily A. Department of Chemistry Northwestern University EvanstonIL60208-3113 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208-3113 United States Department of Electrical Engineering and Computer Science Northwestern University EvanstonIL60208-3113 United States

Mixed-dimensional van der Waals heterojunctions comprising polymer and two-dimensional (2D) semiconductors have many characteristics of an ideal charge separation interface for optoelectronic and photonic applications. However, the photoelectron dynamics at polymer-2D semiconductor heterojunction interfaces are currently not sufficiently understood to guide the optimization of devices for these applications. This manuscript is a report of a systematic exploration of the time-dependent photophysical processes that occur upon photoexcitation of a type-II heterojunction between the polymer PTB7 and monolayer MoS2. In particular, photoinduced electron transfer from PTB7 to electronically hot states of MoS2 occurs in less than 250 fs. This process is followed by a slower (1-5 ps) exciton diffusion-limited electron transfer from PTB7 to MoS2 with a yield of 58%, and a sub-3-ps photoinduced hole transfer from MoS2 to PTB7. The equilibrium between excitons and polaron pairs in PTB7 determines the charge separation yield, whereas the 3-4 ns lifetime of photogenerated carriers is limited by MoS2 defects. Overall, this work elucidates the mechanisms of ultrafast charge carrier dynamics at PTB7-MoS2 interfaces, which will inform ongoing efforts to exploit polymer-2D semiconductor heterojunctions for photovoltaic and photodetector applications. Copyright © 2018, The Authors. All rights reserved.

关键词： Molybdenum compounds

T-Operator limits on optical communication: Metaoptics, computation, and input–output transformations

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arXiv 2021年

作者： Molesky, Sean Chao, Pengning Mohajan, Jewel Reinhart, Wesley Chi, Heng Rodriguez, Alejandro W. Department of Electrical and Computer Engineering Princeton University PrincetonNJ08544 United States Department of Materials Science and Engineering Pennsylvania State University University ParkPA16802 United States Siemens PrincetonNJ08540 United States

We present an optimization framework based on Lagrange duality and the scattering T operator of electromagnetism to construct limits on the possible features that may be imparted to a collection of output fields from a collection of input fields, i.e., constraints on achievable optical transformations and the characteristics of structured materials as communication channels. Implications of these bounds on the performance of representative optical devices having multi-wavelength or multi-port functionalities are examined in the context of electromagnetic shielding, focusing, near-field resolution, and linear computing. © 2021, CC BY.

关键词： Optical communication