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arXiv 2019年

作者： Haleoot, Raad Hamad, Bothina Microelectronics and Photonics graduate program University of Arkansas FayettevilleAR72701 United States Department of Physics College of Education University of Mustansiriyah Baghdad10052 Iraq Department of Physics University of Arkansas FayettevilleAR72701 United States Physics Department University of Jordan Amman11942 Jordan

Utilizing a material in thermoelectric applications requires a mechanical, thermal, and lattice stability as well a high figure of merit (ZT). In this work, we present the structural, electronic, magnetic, mechanical, thermodynamic, dynamic, and thermoelectric properties of CoFeYGe (Y = Ti, Cr) quaternary Heusler compounds using the density functional theory (DFT). The calculated mechanical properties and phonon dispersions reveal that the structures of these compounds are stable. Both CoFeCrGe and CoFeTiGe compounds show a ferromagnetic and ferrimagnetic half-metallic behavior with band gaps of 0.41 and 0.38 eV, respectively. The lattice thermal conductivity (κL) exhibits low values that reach 3.01 W/(m.K) (3.47 W/(m.K)) for CoFeCrGe (CoFeTiGe) at 1100 K. The optical phonon modes have a large contribution of 60.2% (70.9 %) to κL value for CoFeCrGe (CoFeTiGe). High ZT values of 0.71 and 0.65 were obtained for CoFeCrGe and CoFeTiGe, respectively. Based on our calculations, CoFeCrGe and CoFeTiGe combine both good spintronic and thermoelectric behaviors that may be used in spin injection applications. Copyright © 2019, The Authors. All rights reserved.

关键词： Density functional theory

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Study of SiGeSn/GeSn single quantum well towards high-performance all-group-IV optoelectronics

arXiv

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arXiv 2020年

作者： Abernathy, Grey Zhou, Yiyin Ojo, Solomon Alharthi, Bader Grant, Perry C. Du, Wei Margetis, Joe Tolle, John Kuchuk, Andrian Li, Baohua Yu, Shui-Qing Department of Electrical Engineering University of Arkansas FayettevilleAR72701 United States Microelectronics-Photonics Program University of Arkansas FayettevilleAR72701 United States Department of Electrical Engineering and Physics Wilkes University Wilkes BarrePA18766 United States School of Electrical Energy and Computer Engineering Arizona State University TempeAZ85287 United States Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States Arktonics LLC 1339 South Pinnacle Drive FayettevilleAR72701 United States

The recent progress on (Si)GeSn optoelectronic devices holds a great promising for photonic integration on the Si substrate. In parallel to the development of bulk devices, the (Si)GeSn based quantum wells (QWs) have been investigated aiming to improve the device performance. While the multiple QW structure is preferred for the device application, the single quantum well (SQW) is more suitable for optical property study. In this work, a comprehensive study of a SiGeSn/GeSn SQW was conducted. The calculated band diagram provided the band alignment and energies of possible transitions. The SQW features the direct bandgap well with L-Γ valley energy separation of 50 meV, and the barrier heights for both electron and hole are greater than 80 meV. Using two continuous-wave and two pulsed pumping lasers, the analysis of PL spectra allows for identifying different transitions and for better understanding the SQW optical properties. The study could provide the guidance for advancing the future QW design towards device applications. Copyright © 2020, The Authors. All rights reserved.

关键词： Optical properties

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AFM based Topography Characterization of Smooth, Nanotextured, and Microtextured Surfaces

AFM based Topography Characterization of Smooth, Nanotexture...

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IEEE International Conference on Micro/Nano Sensors for AI, Healthcare, and Robotics

作者： Uchechukwu C. Wejinya Guangyi Shi Abayomi Omolewu Department of Mechanical Engineering University of Arkansas Peking University Shenzhen Graduate School Microelectronics-Photonics Graduate Program University of Arkansas

ISBN: (纸本)9781538694091;9781538694084

Surface topography is important to the function of many kinds of industrial products and is constantly growing with the increase advancement of technology. It is important to understand surface topography measurement and how to control it effectively. Surface roughness is an important parameter of topography characterization and is quantified by the vertical deviations of a real surface from its ideal form. Therefore, depending on the application it may be desirable to have either a rough surface or a very smooth surface. Rough surfaces can be desirable for cell adhesion and plays a great role in biological or biomedical application. Smooth surfaces can be desirable in applications where there are two interacting surfaces and minimal wear between the two is needed. This work addresses the surface topography characterizing of a smooth, nanotextured, and microtextured surface.

关键词： Rough surfaces Surface roughness Surface topography Surface texture Surface treatment Response surface methodology

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Structural phases arising from reconstructive and isostructural transitions in high-melting-point oxides under hydrostatic pressure: A first-principles study

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Physical Review B 2018年第2期97卷 020103(R)-020103(R)页

作者： Hao Tian Xiao-Yu Kuang Ai-Jie Mao Yurong Yang Changsong Xu S. Omid Sayedaghaee L. Bellaiche Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Microelectronics-Photonics Program and Physics Department University of Arkansas Fayetteville Arkansas 72701 USA

High-melting-point oxides of chemical formula ABO3 with A=Ca, Sr, Ba and B=Zr, Hf are investigated as a function of hydrostatic pressure up to 200 GPa by combining first-principles calculations with a particle swarm optimization method. Ca- and Sr-based systems: (1) first undergo a reconstructive phase transition from a perovskite state to a novel structure that belongs to the post-post-perovskite family and (2) then experience an isostructural transition to a second, also new post-post-perovskite state at higher pressures, via the sudden formation of a specific out-of-plane B−O bond. In contrast, the studied Ba compounds evolve from a perovskite phase to a third novel post-post-perovskite structure via another reconstructive phase transition. The original characteristics of these three different post-post-perovskite states are emphasized. Unusual electronic properties, including significant piezochromic effects and an insulator-metal transition, are also reported and explained.

关键词： Phase transitions Pressure effects Crystal structures Oxides Perovskites First-principles calculations High-throughput calculations

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Novel Dynamical Magnetoelectric Effects in Multiferroic BiFeO3

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Physical Review Letters 2019年第9期122卷 097601-097601页

作者： S. Omid Sayedaghaee Bin Xu Sergey Prosandeev Charles Paillard L. Bellaiche Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Microelectronics-Photonics Program University of Arkansas Fayetteville Arkansas 72701 USA School of Physical Science and Technology Soochow University Suzhou Jiangsu 215006 China Institute of Physics and Physics Department of Southern Federal University Rostov-na-Donu 344090 Russia Laboratoire Structures Propriétés et Modélisation des Solides CentraleSupélec CNRS UMR 8580 Université Paris-Saclay 91190 Gif-sur-Yvette France

An atomistic effective Hamiltonian scheme is employed within molecular dynamics simulations to investigate how the electrical polarization and magnetization of the multiferroic BiFeO3 respond to time-dependent ac magnetic fields of various frequencies, as well as to reveal the frequency dependency of the dynamical (quadratic) magnetoelectric coefficient. We found the occurrence of vibrations having phonon frequencies in both the time dependency of the electrical polarization and magnetization (for any applied ac frequency), therefore making such vibrations of electromagnonic nature, when the homogeneous strain of the system is frozen (case 1). Moreover, the quadratic magnetoelectric coupling constant is monotonic and almost dispersionless in the sub-THz range in this case 1. In contrast, when the homogeneous strain can fully relax (case 2), two additional low-frequency and strain-mediated oscillations emerge in the time-dependent behavior of the polarization and magnetization, which result in resonances in the quadratic magnetoelectric coefficient. Such additional oscillations consist of a mixing between acoustic phonons, optical phonons, and magnons, and reflect the existence of a new quasiparticle that can be coined an “electroacoustic magnon.” This latter finding can prompt experimentalists to shape their samples to take advantage of, and tune, the magnetostrictive-induced mechanical resonance frequency, in order to achieve large dynamical magnetoelectric couplings.

关键词： Ferroelectricity Magnetoelectric effect Magnons Antiferromagnets Multiferroics Molecular dynamics

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Electrically injected GeSn lasers on Si operating up to 100 K

arXiv

引用

arXiv 2020年

作者： Zhou, Yiyin Miao, Yuanhao Ojo, Solomon Tran, Huong Abernathy, Grey Grant, Joshua M. Amoah, Sylvester Salamo, Gregory Du, Wei Liu, Jifeng Margetis, Joe Tolle, John Zhang, Yong-Hang Sun, Greg Soref, Richard A. Li, Baohua Yu, Shui-Qing Department of Electrical Engineering University of Arkansas FayettevilleAR72701 United States Microelectronics-Photonics Program University of Arkansas FayettevilleAR72701 United States Department of Physics University of Arkansas FayettevilleAR72701 United States Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States Department of Electrical Engineering and Physics Wilkes University Wilkes-BarrePA18766 United States Thayer School of Engineering Dartmouth College HanoverNH03755 United States School of Electrical Energy and Computer Engineering Arizona State University TempeAZ85287 United States Department of Engineering University of Massachusetts Boston BostonMA02125 United States Arktonics LLC 1339 South Pinnacle Drive FayettevilleAR72701 United States

The significant progress of GeSn material development has enabled a feasible solution to the long-desired monolithically integrated lasers on the Si platform. While there are many reports focused on optically pumped lasers, GeSn lasers through electrical injection have not been experimentally achieved yet. In this work, we report the first demonstration of electrically injected GeSn lasers on Si. A GeSn/SiGeSn heterostructure diode grown on a Si substrate was fabricated into ridge waveguide laser devices and tested under pulsed conditions. Special considerations were given for the structure design to ensure effective carrier confinement and optical confinement that lead to lasing. Lasing was observed at temperatures from 10 to 100 K with emission peaks at around 2300 nm. The minimum threshold of 598 A/cm2 was recorded at 10 K and the threshold increased to 842 A/cm2 at 77 K. The spectral linewidth of a single peak was measured as small as 0.13 nm (0.06 meV). The maximum characteristic temperature was extracted as 99 K over the temperature range of 10-77 K. Copyright © 2020, The Authors. All rights reserved.

关键词： Germanium alloys

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Improved optical enhancement using double-width plasmonic gratings with nanogaps

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photonics Research 2016年第5期4卷 173-180页

作者： Ahmad A.Darweesh Stephen J.Bauman Joseph B.Herzog Microelectronics-Photonics Graduate Program University of Arkansas Department of Physics University of Arkansas

Plasmonic grating structures have been shown effective at increasing near-field optical enhancement. A doublewidth plasmonic grating design is introduced, where each period has two alternating metal widths separated by a nanogap. With this new design, analysis has shown that plasmonic resonances couple between each metal section,resulting in even greater optical enhancement compared with single-width gratings. The geometry that gives the greatest optical enhancement has been determined with a computational model. This work demonstrates that the increased enhancement is due to hybridized modes that couple between the two grating segments.

关键词： Improved optical enhancement using double-width plasmonic gratings with nanogaps nm

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Compactly Packaged High-Speed Optical Transceiver Using Silicon photonics ICs on Ceramic Submount

Compactly Packaged High-Speed Optical Transceiver Using Sili...

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IEEE Electronic Components and Technology Conference

作者： Do-Won Kim Andy Lim Eu Jin M. Kumarasamy Raja Vishal Vinayak Kulkarni Leong Ching Wai Jason Liow Tsung Yang Patrick Lo Guo Qiang Nano Photonics Program Institute of Microelectronics (IME) Singapore

High-speed optical module is demonstrated using silicon photonics integrated circuits (Si-PIC) by compact packaging on ceramic submount of which size is 4 mm × 21 mm × 1.1 mm. The electronic integrated circuits (EIC) such as transimpedance amplifier (TIA) for photodetector and driver IC for modulator are flip-chip bonded on the submount using 1 mil diameter of Au stud bumps. The optical transceiver is packaged through the flip-chip bonding of the packaged submount by SAC solders on the evaluation PCB on which RF signal transmission lines are precisely designed. The reliable flip-chip bonding state of the EICs and submount are verified through shear test and X-ray image. Eye diagram is demonstrated at 20 Gbps for receiver module.

关键词： Optical transceiver Silicon photoncis Ceramic submount Compact packaging Flip-chip bonding Stud bumping

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All inorganic quantum dot light emitting devices with solution processed metal oxide transport layers

All inorganic quantum dot light emitting devices with soluti...

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作者： Vasan, R. Salman, H. Manasreh, M.O. Department of Electrical Engineering University of Arkansas FayettevilleAR72701 United States Microelectronics and Photonics program University of Arkansas FayettevilleAR72701 United States

All inorganic quantum dot light emitting devices with solution processed transport layers are investigated. The device consists of an anode, a hole transport layer, a quantum dot emissive layer, an electron transport layer and a cathode. Indium tin oxide coated glass slides are used as substrates with the indium tin oxide acting as the transparent anode electrode. The transport layers are both inorganic, which are relatively insensitive to moisture and other environmental factors as compared to their organic counterparts. Nickel oxide acts as the hole transport layer, while zinc oxide nanocrystals act as the electron transport layer. The nickel oxide hole transport layer is formed by annealing a spin coated layer of nickel hydroxide sol-gel. On top of the hole transport layer, CdSe/ZnS quantum dots synthesized by hot injection method is spin coated. Finally, zinc oxide nanocrystals, dispersed in methanol, are spin coated over the quantum dot emissive layer as the electron transport layer. The material characterization of different layers is performed by using absorbance, Raman scattering, XRD, and photoluminescence measurements. The completed device performance is evaluated by measuring the IV characteristics, electroluminescence and quantum efficiency measurements. The device turn on is around 4V with a maximum current density of ∼200 mA/cm2 at 9 V. MRS Advances © 2016 Materials Research Society.

关键词： Nickel oxide

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Fabrication of an Electrochemical Sensor for Glucose Detection using ZnO Nanorods

Fabrication of an Electrochemical Sensor for Glucose Detecti...

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作者： Mandal, Sanghamitra Marie, Mohammed Manasreh, Omar Department of Electrical Engineering University of Arkansas FayettevilleAR72701 United States Microelectronics Photonics Program University of Arkansas FayettevilleAR72701 United States

An electrochemical glucose sensor based on zinc oxide (ZnO) nanorods is fabricated, characterized and tested. The ZnO nanorods are synthesized on indium titanium oxide (ITO) coated glass substrate, using the hydrothermal sol-gel technique. The working principle of the sensor under investigation is based on the electrochemical reaction taking place between cathode and anode, in the presence of an electrolyte. A platinum plate, used as the cathode and Nafion/Glucose Oxidase/ZnO nanorods/ITO-coated glass substrate used as anode, is immersed in pH 7.0 phosphate buffer solution electrolyte to test for the presence of glucose. Several amperometric tests are performed on the fabricated sensor to determine the response time, sensitivity and limit of detection of the sensor. A fast response time less than 3 s with a high sensitivity of 1.151 mA cm-2mM-1 and low limit of detection of 0.089 mM is reported. The glucose sensor is characterized using the cyclic voltammetry method in the range from -0.8 - 0.8 V with a voltage scan rate of 100 mV/s. © Copyright Materials Research Society 2016.

关键词： Electrolytes

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