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Towards a Novel Broadband Spectrally Dynamic Solid State Light Source

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MRS Online Proceedings Library 2021年第1期892卷 17-22页

作者： David B. Nicol Shalini Gupta Nola Li Ali Asghar Elton Graugnard Chris Summers Ian T. Ferguson School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta U.S.A. EMCORE Corporation Somerset U.S.A. School of Material Science Engineering Georgia Institute of Technology Atlanta U.S.A.

The developments of two major components of a three terminal dual wavelength LED for excitation of multiple phosphors are described. Such a configuration will be novel Broadband Spectrally Dynamic Light Emitting Diode (BSDLED). First, work towards a functional tunnel junction in the GaN system is discussed. The developments of p+ and n+ GaN layers are specifically discussed in relation to their use in a buried current spreading contact layer. Second, the analysis of several phosphors and their application in a spectrally dynamic source is explored. The response to multiple wavelengths of the phosphors is analyzed to create a light source that can be tuned in “real time” to a wide range of correlated color temperatures.

关键词： Ga N devices

High conductivity polarization-induced 2D hole gases in undoped GaN/AlN heterojunctions enabled by Impurity Blocking Layers

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arXiv 2021年

作者： Chaudhuri, Reet Chen, Zhen Muller, David Xing, Huili Grace Jena, Debdeep School of Electrical and Computer Engineering Cornell University Department of Applied and Engineering Physics Cornell University Kavli Institute of Nanoscience Cornell University Department of Material Science and Engineering Cornell University

High-conductivity undoped GaN/AlN 2D hole gases (2DHGs), the p-type dual of the AlGaN/GaN 2D electron gases (2DEGs), have offered valuable insights into hole transport in GaN and enabled the first GaN GHz RF p-channel FETs. They are an important step towards high-speed and high-power complementary electronics with wide-bandgap semiconductors. These technologically and scientifically relevant 2D hole gases are perceived to be not as robust as the 2DEGs because structurally similar heterostructures exhibit wide variations of the hole density over ∆ps > 7×1013 cm-2, and low mobilities. In this work, we uncover that the variations are tied to undesired dopant impurities such as Silicon and Oxygen floating up from the nucleation interface. By introducing impurity blocking layers (IBLs) in the AlN buffer layer, we eliminate the variability in 2D hole gas densities and transport properties, resulting in a much tighter-control over the 2DHG density variations to ∆ps ≤ 1 × 1013 cm-2 across growths, and a 3× boost in the Hall mobilities. These changes result in a 2-3× increase in hole conductivity when compared to GaN/AlN structures without IBLs. Copyright © 2021, The Authors. All rights reserved.

关键词： Gallium nitride

Inverse design of functional photonic patches by adjoint optimization coupled to the generalized Mie theory

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arXiv 2023年

作者： Zhu, Yilin Chen, Yuyao Gorsky, Sean Shubitidze, Tornike Dal Negro, Luca Division of Material Science and Engineering Boston University 15 Saint Mary’s Street BrooklineMA02446 United States Department of Electrical & Computer Engineering Photonics Center Boston University 8 Saint Mary’s Street BostonMA02215 United States Department of Physics Boston University 590 Commonwealth Avenue BostonMA02215 United States

We propose a rigorous approach for the inverse design of functional photonic structures by coupling the adjoint optimization method and the two-dimensional generalized Mie theory (2D-GMT) for the multiple scattering problem of finite-size arrays of dielectric nanocylinders optimized to display desired functions. We refer to these functional scattering structures as "photonic patches". We briefly introduce the formalism of 2D-GMT and the critical steps necessary to implement the adjoint optimization algorithm to photonic patches with designed radiation properties. In particular, we showcase several examples of periodic and aperiodic photonic patches with optimal nanocylinder radii and arrangements for radiation shaping, wavefront focusing in the Fresnel zone, and for the enhancement of the local density of states (LDOS) at multiple wavelengths over micron-size areas. Moreover, we systematically compare the performances of periodic and aperiodic patches with different sizes and find that optimized aperiodic Vogel spiral geometries feature significant advantages in achromatic focusing compared to their periodic counterparts. Our results show that adjoint optimization coupled to 2D-GMT is a robust methodology for the inverse design of compact photonic devices that operate in the multiple scattering regime with optimal desired functionalities. Without the need of spatial meshing, our approach provides efficient solutions at strongly reduced computational burden compared to standard numerical optimization techniques and suggests compact device geometries for on-chip photonics and metamaterials technologies. © 2023 Optical Society of America Copyright © 2023, The Authors. All rights reserved.

关键词： Cylinders (shapes)

A Machine-Learning-Accelerated Quantum Transport Study on the Effects of Superlattice Disorder and Strain in a Mid-wave Infrared Curved Sensor

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arXiv 2023年

作者： Glennon, John Kyrtsos, Alexandros O'Masta, Mark R. Nguyen, Binh-Minh Bellotti, Enrico Division of Material Science and Engineering Boston University BostonMA02215 United States Silvaco Inc. 4701 Patrick Henry Drive Santa ClaraCA95054 United States Department of Electrical and Computer Engineering Boston University BostonMA02215 United States HRL Laboratories LLC 3011 Malibu Canyon Road MalibuCA90265 United States

An emerging device architecture for infrared imaging is the curved focal-plane array which benefits from several optical advantages over the traditional flat design. However, the curving process introduces additional strain in the active region which must be taken into account. Type-II superlattices, a promising alternative to traditional bulk materials for use in infrared photodetectors, is a candidate material for use in these devices, but the transport properties of these highly heterogeneous materials are not straightforward and can be affected by different material conditions, such as superlattice disorder and external strain. We present a comprehensive study of the internal QE calculated for a curved device that incorporates finite element analysis (FEA) modeling, nonequilibirium Green's functions (NEGF) calculations, and Gaussian Process (GP) regression. FEA is used for predicting the strain configuration throughout the active region induced by the curving procedure of the device. NEGF is used to calculate the vertical hole mobility for a select set of strain configurations, from which the internal quantum efficiency of the device is approximated to predict performance under strained conditions. Then this data set is used to train a GP model that maps the quantum efficiency QE predictions onto the spatial coordinates of the curved device, based on the strain configuration predicted using FEA. This analysis is performed for ideal and disordered SLs to understand both the fundamental and practical limitations of the performance of these materials in curved devices. Copyright © 2023, The Authors. All rights reserved.

关键词： Infrared radiation

Enhanced Nonlinearity of Epsilon-Near-Zero Indium Tin Oxide Nanolayers with Tamm Plasmon-Polariton States

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arXiv 2023年

作者： Shubitidze, Tornike Britton, Wesley A. Dal Negro, Luca Department of Electrical & Computer Engineering and Photonics Center Boston University 8 Saint Mary’s Street BostonMA02215 United States Division of Material Science and Engineering Boston University 15 Saint Mary’s Street BrooklineMA02446 United States Department of Physics Boston University 590 Commonwealth Avenue BostonMA02215 United States

Recently, materials with vanishingly small permittivity, known as epsilon-near-zero (ENZ) media, emerged as promising candidates to achieve nonlinear optical effects of unprecedented magnitude on a solid-state platform. In particular, the ENZ behavior of Indium Tin Oxide (ITO) thin films resulted in Kerr-type nonlinearity with non-perturbative refractive index variations that are key to developing more efficient Si-compatible devices with sub-wavelength dimensions such as all-optical switchers, modulators, and novel photon detectors. In this contribution, we propose and demonstrate enhancement of the nonlinear index variation of 30 nm-thick ITO nanolayers by silicon dioxide/silicon nitride (SiO2/SiN) Tamm plasmon-polariton structures fabricated by radio-frequency magnetron sputtering on transparent substrates under different annealing conditions. In particular, we investigate the linear and nonlinear optical properties of ITO thin films and resonant photonic structures using broadband spectroscopic ellipsometry and intensity-dependent Z-scan nonlinear characterization demonstrating enhancement of optical nonlinearity with refractive index variations as large as ∆n ≈ 2 in the non-perturbative regime. Our study reveals that the efficient excitation of strongly confined plasmon-polariton Tamm states substantially boost the nonlinear optical response of ITO nanolayers providing a stepping stone for the engineering of more efficient infrared devices and nanostructures for a broad range of applications including all-optical data processing, nonlinear spectroscopy, sensing, and novel photodetection modalities. Copyright © 2023, The Authors. All rights reserved.

关键词： Tin oxides

Control of Threading Dislocation Formation in La-doped BaSnO3Films Grown by Hybrid Molecular Beam Epitaxy

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Microscopy and Microanalysis 2024年第SUPPLEMENT_1期30卷

作者： Ghosh, Supriya Liu, Fengdeng Jalan, Bharat Andre Mkhoyan, K Department of Chemical Engineering and Material Science University of Minnesota Minneapolis MN United States Department of Electrical and Computer Engineering University of Minnesota Minneapolis MN United States

Exogenous electric field to accelerate wound healing

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Biomedical engineering Communications 2024年第3期3卷 1-2页

作者： Kai-Qi Yang Jia Chen Xiao-Mei Li Si-Yuan Chang Yan-Jun Yang Yan-Ling Hu College of Material Engineering Fujian Agriculture and Forestry UniversityFuzhou 350108 China.2Medical Science and Technology Innovation Center School of RadiologyShandong First Medical University&Shandong Academy of Medical SciencesTai’an 271016 China.3School of Basic Medicine Medical College of Putian UniversityPutian 351100 China.4College of Life and Health Nanjing Polytechnic InstituteNanjing 210048 China.5School of Electrical and Computer Engineering College of EngineeringThe University of GeorgiaAthens 30602USA.

Wound healing is a critical physiological process in living organisms that includes repair cell proliferation and migration,etc.[1,2].While effective wound-healing treatment strategies have been developed in the past,few have actively controlled the behavior of skin cells to accelerate wound healing[3,4].The importance of accelerated wound healing lies in its ability to shorten treatment time,reduce the risk of infection,and lower the cost of *** stimulation can modulate cell behavior during wound healing by simulating endogenous electric fields,boosting cell migration,fibroblast proliferation,and granulation tissue growth more significantly than traditional methods[5-7].However,electrical stimulation devices’size,space limitations,and unsustainability make them challenging to use in clinical surgery,hindering real-time and convenient *** is therefore crucial to explore the miniaturization of electrical stimulation devices to advance the healing of skin wounds in clinical ***,Chen et *** a flexible micro-Zn-MnO2(mZMB)battery-based woundplast for wound management,which shows a promising path in biomedical applications(Figure 1)[8].

关键词： healing wound stimulation

Ultra-efficient and ultra-rapid solar cell de-icing and de-snowing 4

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Ultra-efficient and ultra-rapid solar cell de-icing and de-s...

New Concepts in Solar and Thermal Radiation Conversion IV 2021

作者： Khodakarami, Siavash Li, Longnan Miljkovic, Nenad Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Material Research Laboratory University of Illinois at Urbana-Champaign UrbanaIL61801 United States Kyushu University Fukuoka819-0395 Japan

ISBN: (数字)9781510644878

ISBN: (纸本)9781510644861

Frost formation and snow coverage is troublesome for a wide range of applications including air conditioning, refrigeration, wind turbines, and photovoltaic solar cells. In solar cell applications, snow coverage in winter times and dust coverage lead to a huge power loss. To maintain energy efficiency and operational fidelity, snow, frost, and ice need to be removed in a highly efficient and rapid manner. Even the state-of-the-art de-snowing, defrosting, and de-icing methods suffer from high energy consumption (10 J cm-2) and taking long times (> 1 min.). Here, we integrated a pulse electrothermal heating method with a transparent and self-cleaning nanoengineered coating capable of achieving ultra-efficient and rapid (~ 1 s.) interfacial de-snowing, defrosting, and de-icing. Specifically, the transparency and self-cleaning properties of the coating are designed to remove both snow and dust from solar cells while minimizing the interference to light absorption. We experimentally demonstrate the defrosting performance of our multi-functional coating and show the enhanced efficiency in energy and time for ice and snow removal. This method is applicable to other applications such as heat exchangers, wind turbines, and power transmission lines. © 2021 SPIE

关键词： Solar energy

Capture Agent Free Biosensing using Porous Silicon Arrays and Machine Learning

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arXiv 2022年

作者： Ward, Simon J. Cao, Tengfei Zhou, Xiang Chang, Catie Weiss, Sharon M. Department of Electrical and Computer Engineering Vanderbilt University NashvilleTN37235 United States Department of Interdisciplinary Material Science Vanderbilt University NashvilleTN37235 United States Department of Chemistry Vanderbilt University NashvilleTN37235 United States

Biosensors are an essential tool for medical diagnostics, environmental monitoring and food safety. Typically, biosensors are designed to detect specific analytes through functionalization with the appropriate capture agents. However, the use of capture agents limits the number of analytes that can be simultaneously detected and reduces the robustness of the biosensor. In this work, we report a versatile, capture agent free biosensor platform based on an array of porous silicon (PSi) thin films, which has the potential to robustly detect a wide variety of analytes based on their physical and chemical properties in the nanoscale porous media. The ability of this system to reproducibly classify, quantify, and discriminate three proteins is demonstrated to concentrations down to at least 0.02g/L (between 300nM and 450nM) by utilizing PSi array elements with a unique combination of pore size and buffer pH, employing linear discriminant analysis for dimensionality reduction, and using support vector machines as a classifier. This approach represents a significant step towards a low cost, simple and robust biosensor platform that is able to detect a vast range of biomolecules. © 2022, CC BY-NC-ND.

关键词： Porous silicon