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Electrically injected GeSn lasers with peak wavelength up to 2.7 μm

photonics Research 2022年第1期10卷 222-229页

作者： YIYIN ZHOU SOLOMON OJO CHEN-WEI WU YUANHAO MIAO HUONG TRAN JOSHUA MGRANT GREY ABERNATHY SYLVESTER AMOAH JAKE BASS GREGORY SALAMO WEI DU GUO-EN CHANG JIFENG LIU JOE MARGETIS JOHN TOLLE YONG-HANG ZHANG GREG SUN RICHARD ASOREF BAOHUA LI SHUI-QING YU Department of Electrical Engineering University of ArkansasFayettevilleArkansas 72701USA Microelectronics-Photonics Program University of ArkansasFayettevilleArkansas 72701USA Department of Mechanical Engineering Taiwan Chung-Cheng UniversityMing-HsiungChiayi 62102China Department of Physics University of ArkansasFayettevilleArkansas 72701USA Institute for Nanoscience and Engineering University of ArkansasFayettevilleArkansas 72701USA Department of Electrical Engineering and Physics Wilkes UniversityWilkes-BarrePennsylvania 18766USA Thayer School of Engineering Dartmouth CollegeHanoverNew Hampshire 03755USA School of Electrical Energy and Computer EngineeringArizona State UniversityTempeArizona 85287USA Department of Electrical Engineering University of Massachusetts BostonBostonMassachusetts 02125USA Arktonics LLCFayettevilleArkansas 72701USA

GeSn lasers enable the monolithic integration of lasers on the Si platform using all-group-Ⅳ direct-bandgap *** GeSn laser study recently moved from optical pumping into electrical *** this work,we present explorative investigations of GeSn heterostructure laser diodes with various layer thicknesses and material *** layer material was studied by using Si_(0.03)Ge_(0.89)Sn_(0.08) and Ge_(0.95)Sn_(0.05),and cap layer total thickness was also *** 190 nm SiGeSn-cap device had threshold of 0.6 kA/cm^(2) at 10 K and a maximum operating temperature(T_(max)) of 100 K,compared to 1.4 kA/cm^(2) and 50 K from 150 nm SiGeSn-cap device,***,the 220 nm GeSn-cap device had 10 K threshold at 2.4 kA/cm^(2) and T_(max) at 90 K,i.e.,higher threshold and lower maximal operation temperature compared to the SiGeSn cap layer,indicating that enhanced electron confinement using SiGeSn can reduce the threshold *** study of the active region material showed that device gain region using Ge_(0.87)Sn_(0.13) had a higher threshold and lower T_(max),compared to Ge_(0.89)Sn_(0.11).The performance was affected by the metal absorption,free carrier absorption,and possibly defect density *** maximum peak wavelength was measured as 2682 nm at 90 K by using Ge_(0.87)Sn_(0.13) in gain *** investigations provide directions to the future GeSn laser diode designs toward the full integration of group-Ⅳ photonics on a Si platform.

关键词： GeSn pumping absorption

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Study of simulations of double graded InGaN solar cell structures

arXiv

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arXiv 2021年

作者： Sarollahi, Mirsaeid Aldawsari, Manal A. Allaparthi, Rohith Refaei, Malak A. Alhelais, Reem Maruf, Helal Uddin Mazur, Yuriy Ware, Morgan E. University of Arkansas Electrical Engineering Department 3217 Bell Engineering Center FayettevilleAR72701 United States University of Arkansas Microelectronics-Photonics Program 731 West Dickson Street FayettevilleAR72701 United States University of Arkansas Material Science and Engineering 731 West Dickson Street FayettevilleAR72701 United States Institute for Nanoscience and Engineering FayettevilleAR72701 United States

The performances of various configurations of InGaN solar cells are compared using nextnano software. Here we compare a flat base graded wall GaN/InGaN structure, with an InxGa1-xN well with sharp GaN contact layers, and an InxGa1-xN structure with InxGa1-xN contact layers, i.e. a homojunction. The doping in the graded structures are the result of polarization doping at each edge (10 nm from each side) due to the graded structure, while the well structures are intentionally doped at each edge (10 nm from each side) equal to the doping concentration in the graded structure. The solar cells are characterized by their open-circuit voltage, Vroc, short circuit current, Isc, solar efficiency, η, and energy band diagram. The results indicate that an increase in Isc and η results from increasing both the fixed and the maximum indium compositions, while the Vroc decreases. The maximum efficiency is obtained for the InGaN well with 60% In. © 2021, CC BY.

关键词： III-V semiconductors

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Optomechanical dissipative solitons (vol 600, pg 75, 2021)

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NATURE 2022年第7896期602卷 E24-E24页

作者： Zhang, Jing Peng, Bo Kim, Seunghwi Monifi, Faraz Jiang, Xuefeng Li, Yihang Yu, Peng Liu, Lianqing Liu, Yu-xi Alu, Andrea Yang, Lan Department of Electrical and Systems Engineering Washington University St. Louis MO USA Department of Automation Tsinghua University Beijing P. R. China Photonics Initiative Advanced Science Research Center City University of New York New York NY USA Physics Program Graduate Center City University of New York New York NY USA State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang P. R. China Institute of Microelectronics Tsinghua University Beijing P. R. China

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Assembly Controlled by Shape

Assembly Controlled by Shape

引用

作者： Lisunova, Milana O. School of Materials Science and Engineering and School of Chemistry and Biochemistry Georgia Institute of Technology AtlantaGA30332 United States MicroElectronics-Photonics Program Institute for Nanoscience and Engineering Ralph E. Martin Department of Chemical Engineering FayettevilleAR72701 United States

To research the impact of the shape on the assembly of the natural objects (protein, virus, bacteria, living cells) the polymer microcapsules with similar surface chemistry and different by shape (spherical, cubical and tetrahedral) had been synthesized. It was found that the energetically favourable face-To-face attachment of anisotropic microcapsules drives the formation of stable and compacted assembly while isotropic microcapsules assembly is mobile and chain-like structures with a point like a contact area. The difference in assembling behaviour of anisotropic (cubic, tetrahedral) and isotropic (spherical) microparticles is related to the fact that the interfacial hydrophobic energies between the anisotropic microparticles are 6-4 orders of magnitude higher than that for the isotropic microparticles due to the significantly higher contact area of anisotropic microparticles. Such mimicking of the natural objects by polymer microcapsules and research their interaction driven by shape explains the arrangements of isotropic and anisotropic cells in bacteria and its mobility. Copyright © Materials Research Society 2018.

关键词： Self assembly

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Dehydration Sensing of a Polyvinyl Alcohol Film via Plasmonic Nanoparticles

Dehydration Sensing of a Polyvinyl Alcohol Film via Plasmoni...

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MRS Advances

作者： Lisunova, Milana O. School of Materials Science and Engineering School of Chemistry and Biochemistry Georgia Institute of Technology AtlantaGA30332 United States MicroElectronics-Photonics Program Institute for Nanoscience and Engineering Ralph E. Martin Department of Chemical Engineering 3202 Bell Engineering Center University of Arkansas FayettevilleAR72701 United States

In situ, real-time monitoring of a dehydration of poly(vinyl alcohol) (PVA) film is researched. The technique based on the incorporation plasmonic nanocages (NCs) between the two identical layers of PVA, (PVA)/NCs/(PVA) film, and its sensitivity to the variation of the refractive index of the surrounding PVA film via desorption water. The dehydration time increases from 180 (s) to 1800 (s) as the content of the PVA in the films increases twice, from (PVA)/NCs/(PVA) to (PVA)2/NCs/(PVA)2. Such effect could be explained by different rate of the molecules desorption from the PVA based films. Specifically, the dehydration rate is of 0.22 (vol% per s) and 0.026 (vol% per s) for (PVA)/NCs/(PVA) and (PVA)2/NCs/(PVA)2 films, respectively. The dehydration rate constant reduces from -50×10-4 (s-1) to -4.3 ×10-4 (s-1) as the content of PVA increases from (PVA)/NCs/(PVA) to (PVA)2/NCs/(PVA)2 films, respectively. © Materials Research Society 2019.

关键词： Plasmonics

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Exploring Convergence of Snake-Skin-Inspired Texture Designs and Additive Manufacturing for Mechanical Traction

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Procedia Manufacturing 2019年 34卷 640-646页

作者： Catherine Tiner Salil Bapat Subrata Deb Nath Sundar V. Atre Ajay Malshe Microelectronics-Photonics Graduate Program University of Arkansas Fayetteville AR 72701 USA Department of Mechanical Engineering University of Arkansas Fayetteville AR 72701 USA Materials Innovation Guild University of Louisville Louisville KY 40208 USA

This research explores the convergence of a 3D printing process with snake-skin-inspired textures for mechanical traction. The design attributes of snake skin scales were studied via the shed skin of species Python Regius . Snake skin design, especially on ventricular side, consists of hexagonal scale patterns with denticulations and fibrils as hierarchical structures of the design. The snake-skin-inspired design was then explored for printing using the laser-powder bed fusion (L-PBF) manufacturing technique on 420 stainless steel. It was discovered that the surface roughness generated by the laser scanning path during the 3D printing technique closely mimics the hierarchical micro-texture of snake skin scales. The texture of the 3D printed part surface was measured using the JIS B 06061-2001 standard by a laser scanning microscope and this manuscript presents a comparison of the 3D printed texture with the shed snake skin surface. This paper also discusses directional traction properties of the printed surface using tribological study.

关键词： Bio-inspired Design 3D Printing Surface Texture

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Anomalous, non-Gaussian, viscoelastic, and age-dependent dynamics of histonelike nucleoid-structuring proteins in live Escherichia coli

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Physical Review E 2018年第4期98卷 042411-042411页

作者： Asmaa A. Sadoon Yong Wang Department of Physics Microelectronics-Photonics Graduate Program Cell and Molecular Biology Program University of Arkansas Fayetteville Arkansas 72701 USA

We report our measurements of the dynamics of histonelike nucleoid-structuring (H-NS) proteins, which interact with both proteins and DNA simultaneously, in live Escherichia coli bacteria. The dynamics turn out to differ significantly from other molecules reported previously. A power-law distribution was observed for the diffusion coefficients of individual H-NS proteins. In addition, we observed a distribution of displacements which does not follow the Gaussian, Cauchy, or Laplace distributions but the Pearson Type VII distribution. Furthermore, we experimentally measured the time and frequency dependence of the complex modulus of the bacterial cytoplasm, which deviates from the viscoelasticity of homogeneous protein solutions and shows a glass-liquid transition. Last, we observed that the dynamics of H-NS proteins is cell length and cell age dependent. The findings are expected to fundamentally change the current views on bacterial cytoplasm and diffusional dynamics of molecules in bacteria.

关键词： Anomalous diffusion Viscoelasticity

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Mechanical-energy-based amplifiers for probing interactions of DNA with metal ions

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Physical Review E 2018年第6期98卷 062403-062403页

作者： Jack Freeland Prabhat Khadka Yong Wang Department of Physics Microelectronics-Photonics Graduate Program Cell and Molecular Biology Program University of Arkansas Fayetteville Arkansas 72701 USA

We report our development of a simple and cost-effective method to amplify and probe the interactions of DNA with metal ions, which are important for various fundamental processes in living systems. This method is based on perturbing energy landscapes using mechanical energy stored in bent DNA molecules. In this proof-of-principle study, the mechanical-energy-based amplifiers were applied to examine the interactions between DNA and Mg2+ ions or Ag+ ions. We demonstrated that interactions between DNA and Mg2+ or Ag+ ions, which are not detectable using gel electrophoresis without amplification, can be easily measured using our molecular amplifiers. In addition, we showed that quantitative details about the DNA-metal interactions can be estimated using our method. Our method is simple, sensitive, and cost-effective. We expect that the developed method will be useful for various applications.

关键词： Biomechanics DNA

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Growth and strain engineering of trigonal te for topological quantum phases in non-symmorphic chiral crystals

arXiv

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arXiv 2019年

作者： Basnet, Rabindra Doha, M. Hasan Hironaka, Takayuki Pandey, Krishna Davari, Shiva Welch, Katie M. Churchill, Hugh O. H. Hu, Jin Department of Physics University of Arkansas Fayetteville72701 United States Institute for Nanoscience and Engineering University of Arkansas Fayetteville72701 United States Microelectronics-Photonics Graduate Program University of Arkansas Fayetteville72701 United States

Strained trigonal Te has been predicted to host Weyl nodes supported by a nonsymmorphic chiral symmetry. Using low-pressure physical vapor deposition, we systematically explored the growth of trigonal Te nanowires with naturally occurring strain caused by curvature of the wires. Raman spectra and high mobility electronic transport attest to the highly crystalline nature of the wires. Comparison of Raman spectra for both straight and curved nanowires indicates a breathing mode that is significantly broader and shifted in frequency for the curved wires. Strain induced by curvature during growth therefore may provide a simple pathway to investigate topological phases in trigonal Te. Copyright © 2019, The Authors. All rights reserved.

关键词： Nanowires

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Optical and Atomic Force Microscopy Study of Non-covalently functionalized CVD Graphene

Optical and Atomic Force Microscopy Study of Non-covalently ...

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IEEE International Conference on Nano/Micro Engineered and Molecular Systems

作者： Abayomi Omolewu Guangyi Shi Tian Ryan Xiangbo Meng Uchechukwu Wejinya Microelectronics-Photonics Graduate Program University of Arkansas Fayetteville Arkansas USA Scics Peking University at Wuxi Wuxi China Chemistry and Biochemistry Department University of Arkansas Fayetteville Arkansas USA Department of Mechanical Engineering University of Arkansas Fayetteville Arkansas USA

Chemical functionalization is a method that is being explored to take advantage of the intriguing properties of graphene and its derivatives. Surfactant treatments have been successfully employed to non-covalently functionalize graphitic materials such as carbon nanotube and graphite. However, there is still need to investigate the surfactant treatment approach for commercially available chemical vapor deposited (CVD) graphene on silicon-silicon dioxide substrate. CVD graphene is one of the large-scale graphene available;hence, it is essential to understand how surfactants interact with it. This work presents the optical and atomic force microscopy study of non-covalently-functionalized graphene using Sodium Dodecyl Sulphate. CVD graphene on silicon/silicon dioxide (Si/SiO_2) substrates were treated with different surfactant concentrations for different times. Unlike other derivatives of graphene, like carbon nanotube and graphite where the delamination of graphene sheet from the substrate is not a major concern, results show that the stability of the CVD graphene on the substrate is highly dependent on the concentration of the surfactant used for modifying the surface of the graphene, and the duration of treatment. Higher concentration of surfactant treatment was achieved by dissolving the surfactant with water and isopropyl alcohol. The result also suggests that different concentrations of surfactant affect the surface roughness of the functionalized graphene.

关键词： Graphene Surfactants Substrates Delamination Nanoparticles Zinc oxide

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