Normal Isocurvature Surfaces and Special Isocurvature Circles (SIC)

Science.gov (United States)

Manoussakis, Gerassimos; Delikaraoglou, Demitris

2010-05-01

An isocurvature surface of a gravity field is a surface on which the value of the plumblines' curvature is constant. Here we are going to study the isocurvature surfaces of the Earth's normal gravity field. The normal gravity field is a symmetric gravity field therefore the isocurvature surfaces are surfaces of revolution. But even in this case the necessary relations for their study are not simple at all. Therefore to study an isocurvature surface we make special assumptions to form a vector equation which will hold only for a small coordinate patch of the isocurvature surface. Yet from the definition of the isocurvature surface and the properties of the normal gravity field is possible to express very interesting global geometrical properties of these surfaces without mixing surface differential calculus. The gradient of the plumblines' curvature function is vertical to an isocurvature surface. If P is a point of an isocurvature surface and "Φ" is the angle of the gradient of the plumblines' curvature with the equatorial plane then this direction points to the direction along which the curvature of the plumbline decreases / increases the most, and therefore is related to the strength of the normal gravity field. We will show that this direction is constant along a line of curvature of the isocurvature surface and this line is an isocurvature circle. In addition we will show that at each isocurvature surface there is at least one isocurvature circle along which the direction of the maximum variation of the plumblines' curvature function is parallel to the equatorial plane of the ellipsoid of revolution. This circle is defined as a Special Isocurvature Circle (SIC). Finally we shall prove that all these SIC lye on a special surface of revolution, the so - called SIC surface. That is to say, a SIC is not an isolated curve in the three dimensional space.

Semiconductor opto-electronics

CERN Document Server

Moss, TS; Ellis, B

1972-01-01

Semiconductor Opto-Electronics focuses on opto-electronics, covering the basic physical phenomena and device behavior that arise from the interaction between electromagnetic radiation and electrons in a solid. The first nine chapters of this book are devoted to theoretical topics, discussing the interaction of electromagnetic waves with solids, dispersion theory and absorption processes, magneto-optical effects, and non-linear phenomena. Theories of photo-effects and photo-detectors are treated in detail, including the theories of radiation generation and the behavior of semiconductor lasers a

Investigation, study and practice of optoelectronic MOOCs

Science.gov (United States)

Shi, Jianhua; Liu, Wei; Lei, Bing; Yao, Tianfu; Fu, Sihua

2017-08-01

MOOC(Massive Open Online Course) is a new teaching model that has been springing up since 2012. The typical characters are short teaching video, massive learners, flexible place and time to study, etc. Although MOOC is very popular now, opto-electronic MOOCs are not much enough to meet the need of online learners. In this paper, the phylogeny, the current situation and the characters of MOOC were described, the most famous MOOCs' websites, such as Udacity, Coursera, edX, Chinese College MOOC, xuetangx, were introduced, the opto-electronic MOOCs come from these famous MOOCs' website were investigated extensively and studied deeply, the "Application of Opto-electronic Technology MOOC" which was established by our group is introduced, and some conclusions are obtained. These conclusions can give some suggestions to the online learners who are interested in opto-electronic and the teachers who are teaching the opto-electronic curriculums. The preparation of "Opto-electronic Technology MOOC" is described in short.

Deformable paper origami optoelectronic devices

KAUST Repository

He, Jr-Hau

2017-01-19

Deformable optoelectronic devices are provided, including photodetectors, photodiodes, and photovoltaic cells. The devices can be made on a variety of paper substrates, and can include a plurality of fold segments in the paper substrate creating a deformable pattern. Thin electrode layers and semiconductor nanowire layers can be attached to the substrate, creating the optoelectronic device. The devices can be highly deformable, e.g. capable of undergoing strains of 500% or more, bending angles of 25° or more, and/or twist angles of 270° or more. Methods of making the deformable optoelectronic devices and methods of using, e.g. as a photodetector, are also provided.

Light-matter Interactions in Semiconductors and Metals: From Nitride Optoelectronics to Quantum Plasmonics

Science.gov (United States)

Narang, Prineha

This thesis puts forth a theory-directed approach coupled with spectroscopy aimed at the discovery and understanding of light-matter interactions in semiconductors and metals. The first part of the thesis presents the discovery and development of Zn-IV nitride materials. The commercial prominence in the optoelectronics industry of tunable semiconductor alloy materials based on nitride semiconductor devices, specifically InGaN, motivates the search for earth-abundant alternatives for use in efficient, high-quality optoelectronic devices. II-IV-N2 compounds, which are closely related to the wurtzite-structured III-N semiconductors, have similar electronic and optical properties to InGaN namely direct band gaps, high quantum efficiencies and large optical absorption coefficients. The choice of different group II and group IV elements provides chemical diversity that can be exploited to tune the structural and electronic properties through the series of alloys. The first theoretical and experimental investigation of the ZnSnxGe1--xN2 series as a replacement for III-nitrides is discussed here. The second half of the thesis shows ab-initio calculations for surface plasmons and plasmonic hot carrier dynamics. Surface plasmons, electromagnetic modes confined to the surface of a conductor-dielectric interface, have sparked renewed interest because of their quantum nature and their broad range of applications. The decay of surface plasmons is usually a detriment in the field of plasmonics, but the possibility to capture the energy normally lost to heat would open new opportunities in photon sensors, energy conversion devices and switching. A theoretical understanding of plasmon-driven hot carrier generation and relaxation dynamics in the ultrafast regime is presented here. Additionally calculations for plasmon-mediated upconversion as well as an energy-dependent transport model for these non-equilibrium carriers are shown. Finally, this thesis gives an outlook on the

A full-duplex working integrated optoelectronic device for optical interconnect

Science.gov (United States)

Liu, Kai; Fan, Huize; Huang, Yongqing; Duan, Xiaofeng; Wang, Qi; Ren, Xiaomin; Wei, Qi; Cai, Shiwei

2018-05-01

In this paper, a full-duplex working integrated optoelectronic device is proposed. It is constructed by integrating a vertical cavity surface emitting laser (VCSEL) unit above a resonant cavity enhanced photodetector (RCE-PD) unit. Analysis shows that, the VCSEL unit has a threshold current of 1 mA and a slop efficiency of 0.66 W/A at 849.7 nm, the RCE-PD unit obtains its maximal absorption quantum efficiency of 90.24% at 811 nm with a FWHM of 4 nm. Moreover, the two units of the proposed integrated device can work independently from each other. So that the proposed integrated optoelectronic device can work full-duplex. It can be applied for single fiber bidirectional optical interconnects system.

Photonic Structure-Integrated Two-Dimensional Material Optoelectronics

Directory of Open Access Journals (Sweden)

Tianjiao Wang

2016-12-01

Full Text Available The rapid development and unique properties of two-dimensional (2D materials, such as graphene, phosphorene and transition metal dichalcogenides enable them to become intriguing candidates for future optoelectronic applications. To maximize the potential of 2D material-based optoelectronics, various photonic structures are integrated to form photonic structure/2D material hybrid systems so that the device performance can be manipulated in controllable ways. Here, we first introduce the photocurrent-generation mechanisms of 2D material-based optoelectronics and their performance. We then offer an overview and evaluation of the state-of-the-art of hybrid systems, where 2D material optoelectronics are integrated with photonic structures, especially plasmonic nanostructures, photonic waveguides and crystals. By combining with those photonic structures, the performance of 2D material optoelectronics can be further enhanced, and on the other side, a high-performance modulator can be achieved by electrostatically tuning 2D materials. Finally, 2D material-based photodetector can also become an efficient probe to learn the light-matter interactions of photonic structures. Those hybrid systems combine the advantages of 2D materials and photonic structures, providing further capacity for high-performance optoelectronics.

Optoelectronic line transmission an introduction to fibre optics

CERN Document Server

Tricker, Raymond L

2013-01-01

Optoelectronic Line Transmission: An Introduction to Fibre Optics presents a basic introduction as well as a background reference manual on fiber optic transmission. The book discusses the basic principles of optical line transmission; the advantages and disadvantages of optical fibers and optoelectronic signalling; the practical applications of optoelectronics; and the future of optoelectronics. The text also describes the theories of optical line transmission; fibers and cables for optical transmission; transmitters including light-emitting diodes and lasers; and receivers including photodi

Lasers and optoelectronics fundamentals, devices and applications

CERN Document Server

Maini, Anil K

2013-01-01

With emphasis on the physical and engineering principles, this book provides a comprehensive and highly accessible treatment of modern lasers and optoelectronics. Divided into four parts, it explains laser fundamentals, types of lasers, laser electronics & optoelectronics, and laser applications, covering each of the topics in their entirety, from basic fundamentals to advanced concepts. Key features include: exploration of technological and application-related aspects of lasers and optoelectronics, detailing both existing and emerging applications in industry, medical diag

Modulating the Optoelectronic Properties of Silver Nanowires Films: Effect of Capping Agent and Deposition Technique.

Science.gov (United States)

Lopez-Diaz, D; Merino, C; Velázquez, M M

2015-11-11

Silver nanowires 90 nm in diameter and 9 µm in length have been synthesized using different capping agents: polyvinyl pyrrolidone (PVP) and alkyl thiol of different chain lengths. The nanowire structure is not influenced by the displacement of PVP by alkyl thiols, although alkyl thiols modify the lateral aggregation of nanowires. We examined the effect of the capping agent and the deposition method on the optical and electrical properties of films prepared by Spray and the Langmuir-Schaefer methodologies. Our results revealed that nanowires capped with PVP and C8-thiol present the best optoelectronic properties. By using different deposition techniques and by modifying the nanowire surface density, we can modulate the optoelectronic properties of films. This strategy allows obtaining films with the optoelectronic properties required to manufacture touch screens and electromagnetic shielding.

``New'' energy states lead to phonon-less optoelectronic properties in nanostructured silicon

Science.gov (United States)

Singh, Vivek; Yu, Yixuan; Korgel, Brian; Nagpal, Prashant

2014-03-01

Silicon is arguably one of the most important technological material for electronic applications. However, indirect bandgap of silicon semiconductor has prevented optoelectronic applications due to phonon assistance required for photon light absorption/emission. Here we show, that previously unexplored surface states in nanostructured silicon can couple with quantum-confined energy levels, leading to phonon-less exciton-recombination and photoluminescence. We demonstrate size dependence (2.4 - 8.3 nm) of this coupling observed in small uniform silicon nanocrystallites, or quantum-dots, by direct measurements of their electronic density of states and low temperature measurements. To enhance the optical absorption of the these silicon quantum-dots, we utilize generation of resonant surface plasmon polariton waves, which leads to several fold increase in observed spectrally-resolved photocurrent near the quantum-confined bandedge states. Therefore, these enhanced light emission and absorption enhancement can have important implications for applications of nanostructured silicon for optoelectronic applications in photovoltaics and LEDs.

Radiation effects in optoelectronic devices

International Nuclear Information System (INIS)

Barnes, C.E.; Wiczer, J.J.

1984-05-01

Purpose of this report is to provide not only a summary of radiation damage studies at Sandia National Laboratories, but also of those in the literature on the components of optoelectronic systems: light emitting diodes (LEDs), laser diodes, photodetectors, optical fibers, and optical isolators. This review of radiation damage in optoelectronic components is structured according to device type. In each section, a brief discussion of those device properties relevant to radiation effects is given

Nuclear physics and optoelectronics presence in industry, medicine and environment

International Nuclear Information System (INIS)

Robu, Maria; Peteu, Gh.

2000-01-01

This paper reveals applications of Nuclear Physics and Optoelectronics in numerous fields of interest in industry, medicine, environment. In the first part of the work basic elements are analyzed, among which: - the large possibilities offered by the investigation, analysis and testing techniques based on nuclear physics and optoelectronics; - the superior qualitative and quantitative characteristics of these techniques, with varied applicability in fields from industry, medicine and environment. These applications refers to: - elemental analyses of content and impurities; - non-destructive testing with X and gamma radiations; - investigations with radioactive and activable tracers in trophic chains as for instance, ground-vegetation-products-consumers-environment, including also the systemic pollution factors; - complex investigations in the interface tritium-vegetation-environment-humans; - techniques and radiopharmaceutical products for medical investigations; - determinations and automatic control for levels, density, thickness, humidity, surfaces covering; - monitoring by means of remote sensing for the evaluation of the environment, vegetation and pollution factors; - applications and production of laser and UV installations; - connections through optical fibres resistant to radiations; - imaging and medical bioengineering; - advances in X ray, laser and ultrasonic radiology; - monitoring with radiations beams. In the final part, there are presented examples of optoelectronics and nuclear physics applications in fields in industry, medicine and environment, with special stress on their basic characteristics and efficiency. (authors)

Thickness, morphology, and optoelectronic characteristics of pristine and surfactant-modified DNA thin films

International Nuclear Information System (INIS)

Arasu, Velu; Reddy Dugasani, Sreekantha; Son, Junyoung; Gnapareddy, Bramaramba; Ha Park, Sung; Jeon, Sohee; Jeong, Jun-Ho

2017-01-01

Although the preparation of DNA thin films with well-defined thicknesses controlled by simple physical parameters is crucial for constructing efficient, stable, and reliable DNA-based optoelectronic devices and sensors, it has not been comprehensively studied yet. Here, we construct DNA and surfactant-modified DNA thin films by drop-casting and spin-coating techniques. The DNA thin films formed with different control parameters, such as drop-volume and spin-speed at given DNA concentrations, exhibit characteristic thickness, surface roughness, surface potential, and absorbance, which are measured by a field emission scanning electron microscope, a surface profilometer, an ellipsometer, an atomic force microscope, a Kelvin probe force microscope, and an UV–visible spectroscope. From the observations, we realized that thickness significantly affects the physical properties of DNA thin films. This comprehensive study of thickness-dependent characteristics of DNA and surfactant-modified DNA thin films provides insight into the choice of fabrication techniques in order for the DNA thin films to have desired physical characteristics in further applications, such as optoelectronic devices and sensors. (paper)

Ultrafast Graphene Photonics and Optoelectronics

Science.gov (United States)

2017-04-14

AFRL-AFOSR-JP-TR-2017-0032 Ultrafast Graphene Photonics and Optoelectronics Kuang-Hsiung Wu National Chiao Tung University Final Report 04/14/2017...DATES COVERED (From - To) 18 Apr 2013 to 17 Apr 2016 4. TITLE AND SUBTITLE Ultrafast Graphene Photonics and Optoelectronics 5a.  CONTRACT NUMBER 5b...Prescribed by ANSI Std. Z39.18 Final Report for AOARD Grant FA2386-13-1-4022 “Ultrafast Graphene Photonics and Optoelectronics” Date May 23th, 2016

Modulating the Optoelectronic Properties of Silver Nanowires Films: Effect of Capping Agent and Deposition Technique

Directory of Open Access Journals (Sweden)

D. Lopez-Diaz

2015-11-01

Full Text Available Silver nanowires 90 nm in diameter and 9 µm in length have been synthesized using different capping agents: polyvinyl pyrrolidone (PVP and alkyl thiol of different chain lengths. The nanowire structure is not influenced by the displacement of PVP by alkyl thiols, although alkyl thiols modify the lateral aggregation of nanowires. We examined the effect of the capping agent and the deposition method on the optical and electrical properties of films prepared by Spray and the Langmuir-Schaefer methodologies. Our results revealed that nanowires capped with PVP and C8-thiol present the best optoelectronic properties. By using different deposition techniques and by modifying the nanowire surface density, we can modulate the optoelectronic properties of films. This strategy allows obtaining films with the optoelectronic properties required to manufacture touch screens and electromagnetic shielding.

Optoelectronic investigation of nanodiamond interactions with human blood

Science.gov (United States)

Ficek, M.; Wróbel, M. S.; Wasowicz, M.; Jedrzejewska-Szczerska, M.

2016-03-01

We present optoelectronic investigation of in vitro interactions of whole human blood with different nanodiamond biomarkers. Plasmo-chemical modifications of detonation nanodiamond particles gives the possibility for controlling their surface for biological applications. Optical investigations reveal the biological activity of nanodiamonds in blood dependent on its surface termination. We compare different types of nanodiamonds: commercial non-modified detonation nanodiamonds, and nanodiamonds modified by MW PACVD method with H2-termination, and chemically modified nanodiamond with O2-termination. The absorption spectra, and optical microscope investigations were conducted. The results indicate haemocompatibility of non-modified detonation nanodiamond as well as modified nanodiamonds, which enables their application for drug delivery, as well as sensing applications.

Optoelectronics technologies for Virtual Reality systems

Science.gov (United States)

Piszczek, Marek; Maciejewski, Marcin; Pomianek, Mateusz; Szustakowski, Mieczysław

2017-08-01

Solutions in the field of virtual reality are very strongly associated with optoelectronic technologies. This applies to both process design and operation of VR applications. Technologies such as 360 cameras and 3D scanners significantly improve the design work. What is more, HMD displays with high field of view or optoelectronic Motion Capture systems and 3D cameras guarantee an extraordinary experience in immersive VR applications. This article reviews selected technologies from the perspective of their use in a broadly defined process of creating and implementing solutions for virtual reality. There is also the ability to create, modify and adapt new approaches that show team own work (SteamVR tracker). Most of the introduced examples are effectively used by authors to create different VR applications. The use of optoelectronic technology in virtual reality is presented in terms of design and operation of the system as well as referring to specific applications. Designers and users of VR systems should take a close look on new optoelectronics solutions, as they can significantly contribute to increased work efficiency and offer completely new opportunities for virtual world reception.

An introduction to optoelectronic sensors

CERN Document Server

Tajani, Antonella; Cutolo, Antonello

2009-01-01

This invaluable book offers a comprehensive overview of the technologies and applications of optoelectronic sensors. Based on the R&D experience of more than 70 engineers and scientists, highly representative of the Italian academic and industrial community in this area, this book provides a broad and accurate description of the state-of-the-art optoelectronic technologies for sensing. The most innovative approaches, such as the use of photonic crystals, squeezed states of light and microresonators for sensing, are considered. Application areas range from environment to medicine and healthcare

A simple encapsulation method for organic optoelectronic devices

International Nuclear Information System (INIS)

Sun Qian-Qian; An Qiao-Shi; Zhang Fu-Jun

2014-01-01

The performances of organic optoelectronic devices, such as organic light emitting diodes and polymer solar cells, have rapidly improved in the past decade. The stability of an organic optoelectronic device has become a key problem for further development. In this paper, we report one simple encapsulation method for organic optoelectronic devices with a parafilm, based on ternary polymer solar cells (PSCs). The power conversion efficiencies (PCE) of PSCs with and without encapsulation decrease from 2.93% to 2.17% and from 2.87% to 1.16% after 168-hours of degradation under an ambient environment, respectively. The stability of PSCs could be enhanced by encapsulation with a parafilm. The encapsulation method is a competitive choice for organic optoelectronic devices, owing to its low cost and compatibility with flexible devices. (atomic and molecular physics)

Two-dimensional gold nanoparticle arrays. A platform for molecular optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Mangold, Markus Andreas

2011-11-15

In my research, I study the optoelectronic properties of two-dimensional, hexagonal gold nanoparticle arrays formed by self-assembly. When the nanoparticle arrays are embedded in a matrix of alkane thiols, the photoresponse is dominated by a bolometric conductance increase. At room temperature, I observe a strong enhancement of the bolometric photoconductance when the surface plasmon resonance of the nanoparticles is excited. At cryogenic temperatures, the bolometric conductance enhancement leads to a redistribution of the potential landscape which dominates the optoelectronic response of the nanoparticle arrays. When optically active oligo(phenylene vinylene) (OPV) molecules are covalently bound to the nanoparticles, an increased photoconductance due to the resonant excitation of the OPV is observed. The results suggest that the charge carriers, which are resonantly excited in the OPV molecules, directly contribute to the current flow through the nanoparticle arrays. Thus, the conductance of OPV in its excited state is measured in the presented experiments. (orig.)

Introduction to organic electronic and optoelectronic materials and devices

CERN Document Server

Sun, Sam-Shajing

2008-01-01

Introduction to Optoelectronic Materials, N. Peyghambarian and M. Fallahi Introduction to Optoelectronic Device Principles, J. Piprek Basic Electronic Structures and Charge Carrier Generation in Organic Optoelectronic Materials, S.-S. Sun Charge Transport in Conducting Polymers, V.N. Prigodin and A.J. Epstein Major Classes of Organic Small Molecules for Electronic and Optoelectronics, X. Meng, W. Zhu, and H. Tian Major Classes of Conjugated Polymers and Synthetic Strategies, Y. Li and J. Hou Low Energy Gap, Conducting, and Transparent Polymers, A. Kumar, Y. Ner, and G.A. Sotzing Conjugated Polymers, Fullerene C60, and Carbon Nanotubes for Optoelectronic Devices, L. Qu, L. Dai, and S.-S. Sun Introduction of Organic Superconducting Materials, H. Mori Molecular Semiconductors for Organic Field-Effect Transistors, A. Facchetti Polymer Field-Effect Transistors, H.G.O. Sandberg Organic Molecular Light-Emitting Materials and Devices, F. So and J. Shi Polymer Light-Emitting Diodes: Devices and Materials, X. Gong and ...

Dual-scale topology optoelectronic processor.

Science.gov (United States)

Marsden, G C; Krishnamoorthy, A V; Esener, S C; Lee, S H

1991-12-15

The dual-scale topology optoelectronic processor (D-STOP) is a parallel optoelectronic architecture for matrix algebraic processing. The architecture can be used for matrix-vector multiplication and two types of vector outer product. The computations are performed electronically, which allows multiplication and summation concepts in linear algebra to be generalized to various nonlinear or symbolic operations. This generalization permits the application of D-STOP to many computational problems. The architecture uses a minimum number of optical transmitters, which thereby reduces fabrication requirements while maintaining area-efficient electronics. The necessary optical interconnections are space invariant, minimizing space-bandwidth requirements.

FABRICATION, MORPHOLOGICAL AND OPTOELECTRONIC ...

African Journals Online (AJOL)

2014-12-31

Dec 31, 2014 ... porous silicon has better optoelectronic properties than bulk .... Measurement: The morphological properties of PS layer such as nanocrystalline size, the .... excess carrier removal by internal recombination and diffusion.

Perovskite Materials: Solar Cell and Optoelectronic Applications

Energy Technology Data Exchange (ETDEWEB)

Yang, Bin [ORNL; Geohegan, David B [ORNL; Xiao, Kai [ORNL

2017-01-01

Hybrid organometallic trihalide perovskites are promising candidates in the applications for next-generation, high-performance, low-cost optoelectronic devices, including photovoltaics, light emitting diodes, and photodetectors. Particularly, the solar cells based on this type of materials have reached 22% lab scale power conversion efficiency in only about seven years, comparable to the other thin film photovoltaic technologies. Hybrid perovskite materials not only exhibit superior optoelectronic properties, but also show many interesting physical properties such as ion migration and defect physics, which may allow the exploration of more device functionalities. In this article, the fundamental understanding of the interrelationships between crystal structure, electronic structure, and material properties is discussed. Various chemical synthesis and processing methods for superior device performance in solar cells and optoelectronic devices are reviewed.

Optoelectronic lessons as an interdisciplinary lecture

Science.gov (United States)

Wu, Dan; Wu, Maocheng; Gu, Jihua

2017-08-01

It is noticed that more and more students in college are passionately curious about the optoelectronic technology, since optoelectronic technology has advanced extremely quickly during the last five years and its applications could be found in a lot of domains. The students who are interested in this area may have different educational backgrounds and their majors cover science, engineering, literature and social science, etc. Our course "History of the Optoelectronic Technology" is set up as an interdisciplinary lecture of the "liberal education" at our university, and is available for all students with different academic backgrounds from any departments of our university. The main purpose of the course is to show the interesting and colorful historical aspects of the development of this technology, so that the students from different departments could absorb the academic nourishment they wanted. There are little complex derivations of physical formulas through the whole lecture, but there are still some difficulties about the lecture which is discussed in this paper.

Optimization of light out-coupling in optoelectronic devices using nanostructured surface

DEFF Research Database (Denmark)

Ou, Haiyan; Ou, Yiyu; Argyraki, Aikaterini

C and GaN, these developed methods could be applied to other semicon ductors such as Si, etc. Furthermore, all optoelectronic devices having an optical interface such as solar cells, photo - detectors, could benefit from these developed methods for opto - electronic performance improvement....... the overall efficiency of the LEDs. In this paper we have developed various methods for two important semiconductors: silicon carbide (SiC) and gallium nitride (GaN), and demonstrated enormous extraction efficiency enhancement. SiC is an important su bstrate for LED devices. It has refractive index of 2.......6, and only a few percent of light could escape from it. We have developed periodic nanocone structures by using electron - beam lithography, periodic nanodome structures by using nanosphere lithography, random nanostructures by using self - assembled metal nanoparticles, and random nanostructures by directly...

CARBON-FIBRE-REINFORCED POLYMER PARTS EFFECT ON SPACECRAFT OPTOELECTRONIC MODULE LENS SCATTERING

Directory of Open Access Journals (Sweden)

S. S. Kolasha

2016-01-01

Full Text Available Spacecraft optoelectronic modules traditionally have aluminum alloy or titanium alloy casing which substantial weight increases fuel consumption required to put them into orbit and, consequently, total cost of the project. Carbon fiber reinforced polymer based composite constructive materials is an efficient solution that allows reducing weight and dimensions of large optoelectronic modules 1,5–3 times and the coefficient of linear thermal expansion 15–20 times if compared with metals. Optical characteristic is a crucial feature of carbon-fibre-reinforced polymer that determines composite material interaction with electromagnetic emission within the optical range. This work was intended to develop a method to evaluate Carbon fiber reinforced polymer optoelectronic modules casing effect on lens scattering by computer simulation with Zemax application software package. Degrees of scattered, reflected and absorbed radiant flux effect on imaging quality are described here. The work included experimental study in order to determine bidirectional reflectance distribution function by goniometric method for LUP-0.1 carbon fabric check test pieces of EDT-69U epoxy binder with EPOFLEX-0.4 glue layer and 5056-3.5-23-A aluminium honeycomb filler. The scattered emission was registered within a hemisphere above the check test piece surface. Optical detection direction was determined with zenith (0º < θ < 90º and azimuth (0º < φ < 180º angles with 10° increment. The check test piece surface was proved to scatter emission within a narrow angle range (approximately 20° with clear directivity. Carbon fiber reinforced polymers was found to feature integrated reflectance coefficient 3 to 4 times greater than special coatings do. 

Massive ordering and alignment of cylindrical micro-objects by photovoltaic optoelectronic tweezers.

Science.gov (United States)

Elvira, Iris; Muñoz-Martínez, Juan F; Barroso, Álvaro; Denz, Cornelia; Ramiro, José B; García-Cabañes, Angel; Agulló-López, Fernando; Carrascosa, Mercedes

2018-01-01

Optical tools for manipulation and trapping of micro- and nano-objects are a fundamental issue for many applications in nano- and biotechnology. This work reports on the use of one such method, known as photovoltaic optoelectronics tweezers, to orientate and organize cylindrical microcrystals, specifically elongated zeolite L, on the surface of Fe-doped LiNbO 3 crystal plates. Patterns of aligned zeolites have been achieved through the forces and torques generated by the bulk photovoltaic effect. The alignment patterns with zeolites parallel or perpendicular to the substrate surface are highly dependent on the features of light distribution and crystal configuration. Moreover, dielectrophoretic chains of zeolites with lengths up to 100 μm have often been observed. The experimental results of zeolite trapping and alignment have been discussed and compared together with theoretical simulations of the evanescent photovoltaic electric field and the dielectrophoretic potential. They demonstrate the remarkable capabilities of the optoelectronic photovoltaic method to orientate and pattern anisotropic microcrystals. The combined action of patterning and alignment offers a unique tool to prepare functional nanostructures with potential applications in a variety of fields such as nonlinear optics or plasmonics.

Stereoscopic construction and practice of optoelectronic technology textbook

Science.gov (United States)

Zhou, Zigang; Zhang, Jinlong; Wang, Huili; Yang, Yongjia; Han, Yanling

2017-08-01

It is a professional degree course textbook for the Nation-class Specialty—Optoelectronic Information Science and Engineering, and it is also an engineering practice textbook for the cultivation of photoelectric excellent engineers. The book seeks to comprehensively introduce the theoretical and applied basis of optoelectronic technology, and it's closely linked to the current development of optoelectronic industry frontier and made up of following core contents, including the laser source, the light's transmission, modulation, detection, imaging and display. At the same time, it also embodies the features of the source of laser, the transmission of the waveguide, the electronic means and the optical processing methods.

Perspectives in optoelectronics

National Research Council Canada - National Science Library

Jha, Sudhanshu S

1995-01-01

..., optoelectronics is playing a major role in both applied as well as basic sciences. In years to come, i t is destined to change the face of information technology and robotics, involving optical sensing and control, information storage, signal and image processing, communications, and computing. Because of the possibility of using large bandwidths availa...

Terahertz optoelectronics in graphene

International Nuclear Information System (INIS)

Otsuji, Taiichi

2016-01-01

Graphene has attracted considerable attention due to its extraordinary carrier transport, optoelectronic, and plasmonic properties originated from its gapless and linear energy spectra enabling various functionalities with extremely high quantum efficiencies that could never be obtained in any existing materials. This paper reviews recent advances in graphene optoelectronics particularly focused on the physics and device functionalities in the terahertz (THz) electromagnetic spectral range. Optical response of graphene is characterized by its optical conductivity and nonequilibrium carrier energy relaxation dynamics, enabling amplification of THz radiation when it is optically or electrically pumped. Current-injection THz lasing has been realized very recently. Graphene plasmon polaritons can greatly enhance the THz light and graphene matter interaction, enabling giant enhancement in detector responsivity as well as amplifier/laser gain. Graphene-based van der Waals heterostructures could give more interesting and energy-efficient functionalities. (author)

Insulating materials for optoelectronics

International Nuclear Information System (INIS)

Agullo-Lopez, F.

1990-01-01

Optoelectronics is an interdisciplinary field. Basic functions of an optoelectronic system include the generator of the optical signal, its transmission and handling and, finally, its detection, storage and display. A large variety of semiconductor and insulating materials are used or are being considered to perform those functions. The authors focus on insulating materials, mostly oxides. For signal generation, tunable solid state lasers, either vibronic or those based oon colour centres are briefly described, and their main operating parameters summarized. Reference is made to some developments on fiber and waveguide lasers. Relevant physical features of the silica fibres used for low-loss, long-band, optical transmission are reviewed, as well as present efforts to further reduce attenuation in the mid-infrared range. Particular attention is paid to photorefractive materials (LiNbO 3 , BGO, BSO, etc.), which are being investigated

Optoelectronic properties of four azobenzene-based iminopyridine ligands for photovoltaic application

Directory of Open Access Journals (Sweden)

Aziz El alamy

2017-11-01

Full Text Available Because of organic π-conjugated materials’ optoelectronic properties and potential applications in a wide range of electronic and optoelectronic devices, such as organic solar cells, these materials, including both polymers and oligomers, have been widely studied in recent years. This work reposts a theoretical study using the DFT method on four azobenzene-based iminopyridines. The theoretical ground-state geometry, electronic structure and optoelectronic parameters (highest occupied molecular orbital (HOMO, lowest unoccupied molecular orbital (LUMO energy levels, open-circuit voltage (Voc and oscillator strengths (O.S of the studied molecules were obtained using the density functional theory (DFT and time-dependent (TDDFT approaches. The effects of the structure length and substituents on the geometric and optoelectronic properties of these materials are discussed to investigate the relationship between the molecular structure and the optoelectronic properties. The results of this study are consistent with the experimental ones and suggest that these materials as good candidates for use in photovoltaic devices. Keywords: π-conjugated materials, azobenzene, optoelectronic properties, DFT calculations, HOMO-LUMO gap

Understanding and removing surface states limiting charge transport in TiO2 nanowire arrays for enhanced optoelectronic device performance.

Science.gov (United States)

Sheng, Xia; Chen, Liping; Xu, Tao; Zhu, Kai; Feng, Xinjian

2016-03-01

Charge transport within electrode materials plays a key role in determining the optoelectronic device performance. Aligned single-crystal TiO 2 nanowire arrays offer an ideal electron transport path and are expected to have higher electron mobility. Unfortunately, their transport is found not to be superior to that in nanoparticle films. Here we show that the low electron transport in rutile TiO 2 nanowires is mainly caused by surface traps in relatively deep energy levels, which cannot be removed by conventional approaches, such as oxygen annealing treatment. Moreover, we demonstrate an effective wet-chemistry approach to minimize these trap states, leading to over 20-fold enhancement in electron diffusion coefficient and 62% improvement in solar cell performance. On the basis of our results, the potential of TiO 2 NWs can be developed and well-utilized, which is significantly important for their practical applications.

Mid-infrared Semiconductor Optoelectronics

CERN Document Server

Krier, Anthony

2006-01-01

The practical realisation of optoelectronic devices operating in the 2–10 µm (mid-infrared) wavelength range offers potential applications in a variety of areas from environmental gas monitoring around oil rigs and landfill sites to the detection of pharmaceuticals, particularly narcotics. In addition, an atmospheric transmission window exists between 3 µm and 5 µm that enables free-space optical communications, thermal imaging applications and the development of infrared measures for "homeland security". Consequently, the mid-infrared is very attractive for the development of sensitive optical sensor instrumentation. Unfortunately, the nature of the likely applications dictates stringent requirements in terms of laser operation, miniaturisation and cost that are difficult to meet. Many of the necessary improvements are linked to a better ability to fabricate and to understand the optoelectronic properties of suitable high-quality epitaxial materials and device structures. Substantial progress in these m...

Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

Directory of Open Access Journals (Sweden)

Cheng Chuantong

2017-07-01

Full Text Available Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

Science.gov (United States)

Cheng, Chuantong; Huang, Beiju; Mao, Xurui; Zhang, Zanyun; Zhang, Zan; Geng, Zhaoxin; Xue, Ping; Chen, Hongda

2017-07-01

Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs) in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

Advanced educational program in optoelectronics for undergraduates and graduates in electronics

Science.gov (United States)

Vladescu, Marian; Schiopu, Paul

2015-02-01

The optoelectronics education included in electronics curricula at Faculty of Electronics, Telecommunications and Information Technology of "Politehnica" University of Bucharest started in early '90s, and evolved constantly since then, trying to address the growing demand of engineers with a complex optoelectronics profile and to meet the increased requirements of microelectronics, optoelectronics, and lately nanotechnologies. Our goal is to provide a high level of theoretical background combined with advanced experimental tools in laboratories, and also with simulation platforms. That's why we propose an advanced educational program in optoelectronics for both grades of our study program, bachelor and master.

Optical Near-field Interactions and Forces for Optoelectronic Devices

Science.gov (United States)

Kohoutek, John Michael

Throughout history, as a particle view of the universe began to take shape, scientists began to realize that these particles were attracted to each other and hence came up with theories, both analytical and empirical in nature, to explain their interaction. The interaction pair potential (empirical) and electromagnetics (analytical) theories, both help to explain not only the interaction between the basic constituents of matter, such as atoms and molecules, but also between macroscopic objects, such as two surfaces in close proximity. The electrostatic force, optical force, and Casimir force can be categorized as such forces. A surface plasmon (SP) is a collective motion of electrons generated by light at the interface between two mediums of opposite signs of dielectric susceptibility (e.g. metal and dielectric). Recently, surface plasmon resonance (SPR) has been exploited in many areas through the use of tiny antennas that work on similar principles as radio frequency (RF) antennas in optoelectronic devices. These antennas can produce a very high gradient in the electric field thereby leading to an optical force, similar in concept to the surface forces discussed above. The Atomic Force Microscope (AFM) was introduced in the 1980s at IBM. Here we report on its uses in measuring these aforementioned forces and fields, as well as actively modulating and manipulating multiple optoelectronic devices. We have shown that it is possible to change the far field radiation pattern of an optical antenna-integrated device through modification of the near-field of the device. This modification is possible through change of the local refractive index or reflectivity of the "hot spot" of the device, either mechanically or optically. Finally, we have shown how a mechanically active device can be used to detect light with high gain and low noise at room temperature. It is the aim of several of these integrated and future devices to be used for applications in molecular sensing

Optoelectronic Evaluation and Loss Analysis of PEDOT:PSS/Si Hybrid Heterojunction Solar Cells.

Science.gov (United States)

Yang, Zhenhai; Fang, Zebo; Sheng, Jiang; Ling, Zhaoheng; Liu, Zhaolang; Zhu, Juye; Gao, Pingqi; Ye, Jichun

2017-12-01

The organic/silicon (Si) hybrid heterojunction solar cells (HHSCs) have attracted considerable attention due to their potential advantages in high efficiency and low cost. However, as a newly arisen photovoltaic device, its current efficiency is still much worse than commercially available Si solar cells. Therefore, a comprehensive and systematical optoelectronic evaluation and loss analysis on this HHSC is therefore highly necessary to fully explore its efficiency potential. Here, a thoroughly optoelectronic simulation is provided on a typical planar polymer poly (3,4-ethylenedioxy thiophene):polystyrenesulfonate (PEDOT:PSS)/Si HHSC. The calculated spectra of reflection and external quantum efficiency (EQE) match well with the experimental results in a full-wavelength range. The losses in current density, which are contributed by both optical losses (i.e., reflection, electrode shield, and parasitic absorption) and electrical recombination (i.e., the bulk and surface recombination), are predicted via carefully addressing the electromagnetic and carrier-transport processes. In addition, the effects of Si doping concentrations and rear surface recombination velocities on the device performance are fully investigated. The results drawn in this study are beneficial to the guidance of designing high-performance PEDOT:PSS/Si HHSCs.

Integrated optoelectronic materials and circuits for optical interconnects

International Nuclear Information System (INIS)

Hutcheson, L.D.

1988-01-01

Conventional interconnect and switching technology is rapidly becoming a critical issue in the realization of systems using high speed silicon and GaAs based technologies. In recent years clock speeds and on-chip density for VLSI/VHSIC technology has made packaging these high speed chips extremely difficult. A strong case can be made for using optical interconnects for on-chip/on-wafer, chip-to-chip and board-to-board high speed communications. GaAs integrated optoelectronic circuits (IOC's) are being developed in a number of laboratories for performing Input/Output functions at all levels. In this paper integrated optoelectronic materials, electronics and optoelectronic devices are presented. IOC's are examined from the standpoint of what it takes to fabricate the devices and what performance can be expected

RPE cell surface proteins in normal and dystrophic rats

International Nuclear Information System (INIS)

Clark, V.M.; Hall, M.O.

1986-01-01

Membrane-bound proteins in plasma membrane enriched fractions from cultured rat RPE were analyzed by two-dimensional gel electrophoresis. Membrane proteins were characterized on three increasingly specific levels. Total protein was visualized by silver staining. A maximum of 102 separate proteins were counted in silver-stained gels. Glycoproteins were labeled with 3H-glucosamine or 3H-fucose and detected by autoradiography. Thirty-eight fucose-labeled and 61-71 glucosamine-labeled proteins were identified. All of the fucose-labeled proteins were labeled with glucosamine-derived radioactivity. Proteins exposed at the cell surface were labeled by lactoperoxidase-catalyzed radioiodination prior to preparation of membranes for two-dimensional analysis. Forty separate 125I-labeled surface proteins were resolved by two-dimensional electrophoresis/autoradiography. Comparison with the glycoprotein map showed that a number of these surface labeled proteins were glycoproteins. Two-dimensional maps of total protein, fucose-labeled, and glucosamine-labeled glycoproteins, and 125I-labeled surface proteins of membranes from dystrophic (RCS rdy-p+) and normal (Long Evans or RCS rdy+p+) RPE were compared. No differences in the total protein or surface-labeled proteins were observed. However, the results suggest that a 183K glycoprotein is more heavily glycosylated with glucosamine and fucose in normal RPE membranes as compared to membranes from dystrophic RPE

Quantum dot optoelectronic devices: lasers, photodetectors and solar cells

International Nuclear Information System (INIS)

Wu, Jiang; Chen, Siming; Seeds, Alwyn; Liu, Huiyun

2015-01-01

Nanometre-scale semiconductor devices have been envisioned as next-generation technologies with high integration and functionality. Quantum dots, or the so-called ‘artificial atoms’, exhibit unique properties due to their quantum confinement in all 3D. These unique properties have brought to light the great potential of quantum dots in optoelectronic applications. Numerous efforts worldwide have been devoted to these promising nanomaterials for next-generation optoelectronic devices, such as lasers, photodetectors, amplifiers, and solar cells, with the emphasis on improving performance and functionality. Through the development in optoelectronic devices based on quantum dots over the last two decades, quantum dot devices with exceptional performance surpassing previous devices are evidenced. This review describes recent developments in quantum dot optoelectronic devices over the last few years. The paper will highlight the major progress made in 1.3 μm quantum dot lasers, quantum dot infrared photodetectors, and quantum dot solar cells. (topical review)

Secondary treatment of films of colloidal quantum dots for optoelectronics and devices produced thereby

Science.gov (United States)

Semonin, Octavi Escala; Luther, Joseph M; Beard, Matthew C; Chen, Hsiang-Yu

2014-04-01

A method of forming an optoelectronic device. The method includes providing a deposition surface and contacting the deposition surface with a ligand exchange chemical and contacting the deposition surface with a quantum dot (QD) colloid. This initial process is repeated over one or more cycles to form an initial QD film on the deposition surface. The method further includes subsequently contacting the QD film with a secondary treatment chemical and optionally contacting the surface with additional QDs to form an enhanced QD layer exhibiting multiple exciton generation (MEG) upon absorption of high energy photons by the QD active layer. Devices having an enhanced QD active layer as described above are also disclosed.

Integrated Optoelectronic Networks for Application-Driven Multicore Computing

Science.gov (United States)

2017-05-08

AFRL-AFOSR-VA-TR-2017-0102 Integrated Optoelectronic Networks for Application- Driven Multicore Computing Sudeep Pasricha COLORADO STATE UNIVERSITY...AND SUBTITLE Integrated Optoelectronic Networks for Application-Driven Multicore Computing 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-13-1-0110 5c...and supportive materials with innovative architectural designs that integrate these components according to system-wide application needs. 15

Exceptional Optoelectronic Properties of Hydrogenated Bilayer Silicene

Directory of Open Access Journals (Sweden)

Bing Huang

2014-05-01

Full Text Available Silicon is arguably the best electronic material, but it is not a good optoelectronic material. By employing first-principles calculations and the cluster-expansion approach, we discover that hydrogenated bilayer silicene (BS shows promising potential as a new kind of optoelectronic material. Most significantly, hydrogenation converts the intrinsic BS, a strongly indirect semiconductor, into a direct-gap semiconductor with a widely tunable band gap. At low hydrogen concentrations, four ground states of single- and double-sided hydrogenated BS are characterized by dipole-allowed direct (or quasidirect band gaps in the desirable range from 1 to 1.5 eV, suitable for solar applications. At high hydrogen concentrations, three well-ordered double-sided hydrogenated BS structures exhibit direct (or quasidirect band gaps in the color range of red, green, and blue, affording white light-emitting diodes. Our findings open opportunities to search for new silicon-based light-absorption and light-emitting materials for earth-abundant, high-efficiency, optoelectronic applications.

Analysis of optoelectronic strategic planning in Taiwan by artificial intelligence portfolio tool

Science.gov (United States)

Chang, Rang-Seng

1992-05-01

Taiwan ROC has achieved significant advances in the optoelectronic industry with some Taiwan products ranked high in the world market and technology. Six segmentations of optoelectronic were planned. Each one was divided into several strategic items, design artificial intelligent portfolio tool (AIPT) to analyze the optoelectronic strategic planning in Taiwan. The portfolio is designed to provoke strategic thinking intelligently. This computer- generated strategy should be selected and modified by the individual. Some strategies for the development of the Taiwan optoelectronic industry also are discussed in this paper.

Exploration on the training mode of application-oriented talents majoring in optoelectronic information

Science.gov (United States)

Lv, Hao; Liu, Aimei; Zhang, Shengyi; Xiao, Yongjun

2017-08-01

The optoelectronic information major is a strong theoretical and practical specialty. In view of the problems existing in the application-oriented talents training in the optoelectronic information specialty. Five aspects of the talent cultivation plan, the teaching staff, the teaching content, the practical teaching and the scientific research on the training mode of application-oriented talents majoring in optoelectronic information are putted forward. It is beneficial to the specialty construction of optoelectronic information industry which become close to the development of enterprises, and the depth of the integration of school and enterprise service regional economic optoelectronic information high-end skilled personnel base.

Progress on Crystal Growth of Two-Dimensional Semiconductors for Optoelectronic Applications

Directory of Open Access Journals (Sweden)

Bingqi Sun

2018-06-01

Full Text Available Two-dimensional (2D semiconductors are thought to belong to the most promising candidates for future nanoelectronic applications, due to their unique advantages and capability in continuing the downscaling of complementary metal–oxide–semiconductor (CMOS devices while retaining decent mobility. Recently, optoelectronic devices based on novel synthetic 2D semiconductors have been reported, exhibiting comparable performance to the traditional solid-state devices. This review briefly describes the development of the growth of 2D crystals for applications in optoelectronics, including photodetectors, light-emitting diodes (LEDs, and solar cells. Such atomically thin materials with promising optoelectronic properties are very attractive for future advanced transparent optoelectronics as well as flexible and wearable/portable electronic devices.

Deformable paper origami optoelectronic devices

KAUST Repository

He, Jr-Hau; Lin, Chun-Ho

2017-01-01

Deformable optoelectronic devices are provided, including photodetectors, photodiodes, and photovoltaic cells. The devices can be made on a variety of paper substrates, and can include a plurality of fold segments in the paper substrate creating a

Advanced Optoelectronic Devices based on Si Quantum Dots/Si Nanowires Hetero-structures

International Nuclear Information System (INIS)

Xu, J; Zhai, Y Y; Cao, Y Q; Chen, K J

2017-01-01

Si quantum dots are currently extensively studied since they can be used to develop many kinds of optoelectronic devices. In this report, we review the fabrication of Si quantum dots (Si QD) /Si nanowires (Si NWs) hetero-structures by deposition of Si QDs/SiO 2 or Si QDs/SiC multilayers on Si NWs arrays. The electroluminescence and photovoltaic devices based on the formed hetero-structures have been prepared and the improved performance is confirmed. It is also found that the surface recombination via the surface defects states on the Si NWs, especially the ones obtained by the long-time etching, may deteriorate the device properties though they exhibit the better anti-reflection characteristics. The possible surface passivation approaches are briefly discussed. (paper)

Integrated optoelectronic oscillator.

Science.gov (United States)

Tang, Jian; Hao, Tengfei; Li, Wei; Domenech, David; Baños, Rocio; Muñoz, Pascual; Zhu, Ninghua; Capmany, José; Li, Ming

2018-04-30

With the rapid development of the modern communication systems, radar and wireless services, microwave signal with high-frequency, high-spectral-purity and frequency tunability as well as microwave generator with light weight, compact size, power-efficient and low cost are increasingly demanded. Integrated microwave photonics (IMWP) is regarded as a prospective way to meet these demands by hybridizing the microwave circuits and the photonics circuits on chip. In this article, we propose and experimentally demonstrate an integrated optoelectronic oscillator (IOEO). All of the devices needed in the optoelectronic oscillation loop circuit are monolithically integrated on chip within size of 5×6cm 2 . By tuning the injection current to 44 mA, the output frequency of the proposed IOEO is located at 7.30 GHz with phase noise value of -91 dBc/Hz@1MHz. When the injection current is increased to 65 mA, the output frequency can be changed to 8.87 GHz with phase noise value of -92 dBc/Hz@1MHz. Both of the oscillation frequency can be slightly tuned within 20 MHz around the center oscillation frequency by tuning the injection current. The method about improving the performance of IOEO is carefully discussed at the end of in this article.

Parallel optoelectronic trinary signed-digit division

Science.gov (United States)

Alam, Mohammad S.

1999-03-01

The trinary signed-digit (TSD) number system has been found to be very useful for parallel addition and subtraction of any arbitrary length operands in constant time. Using the TSD addition and multiplication modules as the basic building blocks, we develop an efficient algorithm for performing parallel TSD division in constant time. The proposed division technique uses one TSD subtraction and two TSD multiplication steps. An optoelectronic correlator based architecture is suggested for implementation of the proposed TSD division algorithm, which fully exploits the parallelism and high processing speed of optics. An efficient spatial encoding scheme is used to ensure better utilization of space bandwidth product of the spatial light modulators used in the optoelectronic implementation.

Body surface area prediction in normal, hypermuscular, and obese mice.

Science.gov (United States)

Cheung, Michael C; Spalding, Paul B; Gutierrez, Juan C; Balkan, Wayne; Namias, Nicholas; Koniaris, Leonidas G; Zimmers, Teresa A

2009-05-15

Accurate determination of body surface area (BSA) in experimental animals is essential for modeling effects of burn injury or drug metabolism. Two-dimensional surface area is related to three-dimensional body volume, which in turn can be estimated from body mass. The Meeh equation relates body surface area to the two-thirds power of body mass, through a constant, k, which must be determined empirically by species and size. We found older values of k overestimated BSA in certain mice; thus we determined empirically k for various strains of normal, obese, and hypermuscular mice. BSA was computed from digitally scanned pelts and nonlinear regression analysis was used to determine the best-fit k. The empirically determined k for C57BL/6J mice of 9.82 was not significantly different from other inbred and outbred mouse strains of normal body composition. However, mean k of the nearly spheroid, obese lepr(db/db) mice (k = 8.29) was significantly lower than for normals, as were values for dumbbell-shaped, hypermuscular mice with either targeted deletion of the myostatin gene (Mstn) (k = 8.48) or with skeletal muscle specific expression of a dominant negative myostatin receptor (Acvr2b) (k = 8.80). Hypermuscular and obese mice differ substantially from normals in shape and density, resulting in considerably altered k values. This suggests Meeh constants should be determined empirically for animals of altered body composition. Use of these new, improved Meeh constants will allow greater accuracy in experimental models of burn injury and pharmacokinetics.

Research on the application of optoelectronics to nuclear power plants

International Nuclear Information System (INIS)

Shirosaki, Hidekazu; Mitsuda, Hiromichi; Kurata, Toshikazu; Soramoto, Seiki; Maekawa, Tatsuyuki.

1995-01-01

Optoelectronics, which is based on technologies such as laser diodes and optical fibers, is approaching the realm of practical application in the fields of optical fiber communications and compact disks etc,. In addition, laser enrichment, a type of uranium enrichment technique used in the nuclear field, can also be regarded as a product of optoelectronics. Application of optoelectronics in a wide range of fields is likely to continue in the future, and research is being conducted on coherent optical communication, optical integrated circuits, optical computers and other subjects in hopes of attaining practical application of these technologies in the future. On the other hand, digital control equipment and other related devices have been installed and data transfer using optical fibers has been implemented on a partial basis at nuclear power plants, and optoelectronics is anticipated to be applied on an even broader scale in the future, thereby creating the potential for improving plant reliability. In this research, we conducted an investigative study of technologies relating to optoelectronics, and proposed a remote monitoring system for manually operated valves that employs optical switches. Moreover, we conducted theoretical verification tests on the proposed system and carried out a feasibility study relating to application to nuclear power plants. As a result, the proposed system was found to be effective, and confirmed to have the potential of realization as a valve switching monitoring system. (author)

Bioinspired Transparent Laminated Composite Film for Flexible Green Optoelectronics.

Science.gov (United States)

Lee, Daewon; Lim, Young-Woo; Im, Hyeon-Gyun; Jeong, Seonju; Ji, Sangyoon; Kim, Yong Ho; Choi, Gwang-Mun; Park, Jang-Ung; Lee, Jung-Yong; Jin, Jungho; Bae, Byeong-Soo

2017-07-19

Herein, we report a new version of a bioinspired chitin nanofiber (ChNF) transparent laminated composite film (HCLaminate) made of siloxane hybrid materials (hybrimers) reinforced with ChNFs, which mimics the nanofiber-matrix structure of hierarchical biocomposites. Our HCLaminate is produced via vacuum bag compressing and subsequent UV-curing of the matrix resin-impregnated ChNF transparent paper (ChNF paper). It is worthwhile to note that this new type of ChNF-based transparent substrate film retains the strengths of the original ChNF paper and compensates for ChNF paper's drawbacks as a flexible transparent substrate. As a result, compared with high-performance synthetic plastic films, such as poly(ethylene terephthalate), poly(ether sulfone), poly(ethylene naphthalate), and polyimide, our HCLaminate is characterized to exhibit extremely smooth surface topography, outstanding optical clarity, high elastic modulus, high dimensional stability, etc. To prove our HCLaminate as a substrate film, we use it to fabricate flexible perovskite solar cells and a touch-screen panel. As far as we know, this work is the first to demonstrate flexible optoelectronics, such as flexible perovskite solar cells and a touch-screen panel, actually fabricated on a composite film made of ChNF. Given its desirable macroscopic properties, we envision our HCLaminate being utilized as a transparent substrate film for flexible green optoelectronics.

Solution growth of single crystal methylammonium lead halide perovskite nanostructures for optoelectronic and photovoltaic applications.

Science.gov (United States)

Fu, Yongping; Meng, Fei; Rowley, Matthew B; Thompson, Blaise J; Shearer, Melinda J; Ma, Dewei; Hamers, Robert J; Wright, John C; Jin, Song

2015-05-06

Understanding crystal growth and improving material quality is important for improving semiconductors for electronic, optoelectronic, and photovoltaic applications. Amidst the surging interest in solar cells based on hybrid organic-inorganic lead halide perovskites and the exciting progress in device performance, improved understanding and better control of the crystal growth of these perovskites could further boost their optoelectronic and photovoltaic performance. Here, we report new insights on the crystal growth of the perovskite materials, especially crystalline nanostructures. Specifically, single crystal nanowires, nanorods, and nanoplates of methylammonium lead halide perovskites (CH3NH3PbI3 and CH3NH3PbBr3) are successfully grown via a dissolution-recrystallization pathway in a solution synthesis from lead iodide (or lead acetate) films coated on substrates. These single crystal nanostructures display strong room-temperature photoluminescence and long carrier lifetime. We also report that a solid-liquid interfacial conversion reaction can create a highly crystalline, nanostructured MAPbI3 film with micrometer grain size and high surface coverage that enables photovoltaic devices with a power conversion efficiency of 10.6%. These results suggest that single-crystal perovskite nanostructures provide improved photophysical properties that are important for fundamental studies and future applications in nanoscale optoelectronic and photonic devices.

Metamaterial mirrors in optoelectronic devices

KAUST Repository

Esfandyarpour, Majid; Garnett, Erik C.; Cui, Yi; McGehee, Michael D.; Brongersma, Mark L.

2014-01-01

The phase reversal that occurs when light is reflected from a metallic mirror produces a standing wave with reduced intensity near the reflective surface. This effect is highly undesirable in optoelectronic devices that use metal films as both electrical contacts and optical mirrors, because it dictates a minimum spacing between the metal and the underlying active semiconductor layers, therefore posing a fundamental limit to the overall thickness of the device. Here, we show that this challenge can be circumvented by using a metamaterial mirror whose reflection phase is tunable from that of a perfect electric mirror († = €) to that of a perfect magnetic mirror († = 0). This tunability in reflection phase can also be exploited to optimize the standing wave profile in planar devices to maximize light-matter interaction. Specifically, we show that light absorption and photocurrent generation in a sub-100 nm active semiconductor layer of a model solar cell can be enhanced by ∼20% over a broad spectral band. © 2014 Macmillan Publishers Limited.

Metamaterial mirrors in optoelectronic devices

KAUST Repository

Esfandyarpour, Majid

2014-06-22

The phase reversal that occurs when light is reflected from a metallic mirror produces a standing wave with reduced intensity near the reflective surface. This effect is highly undesirable in optoelectronic devices that use metal films as both electrical contacts and optical mirrors, because it dictates a minimum spacing between the metal and the underlying active semiconductor layers, therefore posing a fundamental limit to the overall thickness of the device. Here, we show that this challenge can be circumvented by using a metamaterial mirror whose reflection phase is tunable from that of a perfect electric mirror († = €) to that of a perfect magnetic mirror († = 0). This tunability in reflection phase can also be exploited to optimize the standing wave profile in planar devices to maximize light-matter interaction. Specifically, we show that light absorption and photocurrent generation in a sub-100 nm active semiconductor layer of a model solar cell can be enhanced by ∼20% over a broad spectral band. © 2014 Macmillan Publishers Limited.

Normal Incidence for Graded Index Surfaces

Science.gov (United States)

Khankhoje, Uday K.; Van Zyl, Jakob

2011-01-01

A plane wave is incident normally from vacuum (eta(sub 0) = 1) onto a smooth surface. The substrate has three layers; the top most layer has thickness d(sub 1) and permittivity epsilon(sub 1). The corresponding numbers for the next layer are d(sub 2); epsilon(sub 2), while the third layer which is semi-in nite has index eta(sub 3). The Hallikainen model [1] is used to relate volumetric soil moisture to the permittivity. Here, we consider the relation for the real part of the permittivity for a typical loam soil: acute epsilon(mv) = 2.8571 + 3.9678 x mv + 118:85 x mv(sup 2).

Optoelectronic interconnects for 3D wafer stacks

Science.gov (United States)

Ludwig, David; Carson, John C.; Lome, Louis S.

1996-01-01

Wafer and chip stacking are envisioned as means of providing increased processing power within the small confines of a three-dimensional structure. Optoelectronic devices can play an important role in these dense 3-D processing electronic packages in two ways. In pure electronic processing, optoelectronics can provide a method for increasing the number of input/output communication channels within the layers of the 3-D chip stack. Non-free space communication links allow the density of highly parallel input/output ports to increase dramatically over typical edge bus connections. In hybrid processors, where electronics and optics play a role in defining the computational algorithm, free space communication links are typically utilized for, among other reasons, the increased network link complexity which can be achieved. Free space optical interconnections provide bandwidths and interconnection complexity unobtainable in pure electrical interconnections. Stacked 3-D architectures can provide the electronics real estate and structure to deal with the increased bandwidth and global information provided by free space optical communications. This paper will provide definitions and examples of 3-D stacked architectures in optoelectronics processors. The benefits and issues of these technologies will be discussed.

Optoelectronic switch matrix as a look-up table for residue arithmetic.

Science.gov (United States)

Macdonald, R I

1987-10-01

The use of optoelectronic matrix switches to perform look-up table functions in residue arithmetic processors is proposed. In this application, switchable detector arrays give the advantage of a greatly reduced requirement for optical sources by comparison with previous optoelectronic residue processors.

Contrast image formation based on thermodynamic approach and surface laser oxidation process for optoelectronic read-out system

Science.gov (United States)

Scherbak, Aleksandr; Yulmetova, Olga

2018-05-01

A pulsed fiber laser with the wavelength 1.06 μm was used to treat titanium nitride film deposited on beryllium substrates in the air with intensities below an ablation threshold to provide oxide formation. Laser oxidation results were predicted by the chemical thermodynamic method and confirmed by experimental techniques (X-ray diffraction). The developed technology of contrast image formation is intended to be used for optoelectronic read-out system.

Temperature-Induced Lattice Relaxation of Perovskite Crystal Enhances Optoelectronic Properties and Solar Cell Performance

KAUST Repository

Banavoth, Murali

2016-12-14

Hybrid organic-inorganic perovskite crystals have recently become one of the most important classes of photoactive materials in the solar cell and optoelectronic communities. Albeit improvements have focused on state-of-the-art technology including various fabrication methods, device architectures, and surface passivation, progress is yet to be made in understanding the actual operational temperature on the electronic properties and the device performances. Therefore, the substantial effect of temperature on the optoelectronic properties, charge separation, charge recombination dynamics, and photoconversion efficiency are explored. The results clearly demonstrated a significant enhancement in the carrier mobility, photocurrent, charge carrier lifetime, and solar cell performance in the 60 ± 5 °C temperature range. In this temperature range, perovskite crystal exhibits a highly symmetrical relaxed cubic structure with well-aligned domains that are perpendicular to a principal axis, thereby remarkably improving the device operation. This finding provides a new key variable component and paves the way toward using perovskite crystals in highly efficient photovoltaic cells.

The construction of bilingual teaching of optoelectronic technology

Science.gov (United States)

Zhang, Yang; Zhao, Enming; Yang, Fan; Li, Qingbo; Zhu, Zheng; Li, Cheng; Sun, Peng

2017-08-01

This paper combines the characteristics of optoelectronic technology with that of bilingual teaching. The course pays attention to integrating theory with practice, and cultivating learners' ability. Reform and exploration have been done in the fields of teaching materials, teaching content, teaching methods, etc. The concrete content mainly includes five parts: selecting teaching materials, establishing teaching syllabus, choosing suitable teaching method, making multimedia courseware and improving the test system, which can arouse students' interest in their study and their autonomous learning ability to provide beneficial references for improving the quality of talents of optoelectronic bilingual courses.

GaAs optoelectronic neuron arrays

Science.gov (United States)

Lin, Steven; Grot, Annette; Luo, Jiafu; Psaltis, Demetri

1993-01-01

A simple optoelectronic circuit integrated monolithically in GaAs to implement sigmoidal neuron responses is presented. The circuit integrates a light-emitting diode with one or two transistors and one or two photodetectors. The design considerations for building arrays with densities of up to 10,000/sq cm are discussed.

Advances in graphene-based optoelectronics, plasmonics and photonics

International Nuclear Information System (INIS)

Nguyen, Bich Ha; Nguyen, Van Hieu

2016-01-01

Since the early works on graphene it has been remarked that graphene is a marvelous electronic material. Soon after its discovery, graphene was efficiently utilized in the fabrication of optoelectronic, plasmonic and photonic devices, including graphene-based Schottky junction solar cells. The present work is a review of the progress in the experimental research on graphene-based optoelectronics, plasmonics and photonics, with the emphasis on recent advances. The main graphene-based optoelectronic devices presented in this review are photodetectors and modulators. In the area of graphene-based plasmonics, a review of the plasmonic nanostructures enhancing or tuning graphene-light interaction, as well as of graphene plasmons is presented. In the area of graphene-based photonics, we report progress on fabrication of different types of graphene quantum dots as well as functionalized graphene and graphene oxide, the research on the photoluminescence and fluorescence of graphene nanostructures as well as on the energy exchange between graphene and semiconductor quantum dots. In particular, the promising achievements of research on graphene-based Schottky junction solar cells is presented. (review)

Optoelectronic device with nanoparticle embedded hole injection/transport layer

Science.gov (United States)

Wang, Qingwu [Chelmsford, MA; Li, Wenguang [Andover, MA; Jiang, Hua [Methuen, MA

2012-01-03

An optoelectronic device is disclosed that can function as an emitter of optical radiation, such as a light-emitting diode (LED), or as a photovoltaic (PV) device that can be used to convert optical radiation into electrical current, such as a photovoltaic solar cell. The optoelectronic device comprises an anode, a hole injection/transport layer, an active layer, and a cathode, where the hole injection/transport layer includes transparent conductive nanoparticles in a hole transport material.

Practical opto-electronics an illustrated guide for the laboratory

CERN Document Server

Protopopov, Vladimir

2014-01-01

This book explains how to create opto-electronic systems in a most efficient way, avoiding typical mistakes. It covers light detection techniques, imaging, interferometry, spectroscopy, modulation-demodulation, heterodyning, beam steering, and many other topics common to laboratory applications. The focus is made on self-explanatory figures rather than on words. The book guides the reader through the entire process of creating problem-specific opto-electronic systems, starting from optical source, through beam transportation optical arrangement, to photodetector and data acquisition system. The relevant basics of beam propagation and computer-based raytracing routines are also explained, and sample codes are listed. the book teaches important know-how and practical tricks that are never disclosed in scientific publications.  The book can become the reader's personal adviser in the world of opto-electronics and navigator in the ocean of the market of optical components and systems. Succinct, well-illustrate...

Optoelectronic devices product assurance guideline for space application

Science.gov (United States)

Bensoussan, A.; Vanzi, M.

2017-11-01

New opportunities are emerging for the implementation of hardware sub-systems based on OptoElectronic Devices (OED) for space application. Since the end of this decade the main players for space systems namely designers and users including Industries, Agencies, Manufacturers and Laboratories are strongly demanding of adequate strategies to qualify and validate new optoelectronics products and sub-systems [1]. The long term space application mission will require to address either inter-satellite link (free space communication, positioning systems, tracking) or intra-satellite connectivity/flexibility/reconfigurability or high volume of data transfer between equipment installed into payload.

Advanced Optoelectronic Components for All-Optical Networks

National Research Council Canada - National Science Library

Shapiro, Jeffrey H

2002-01-01

Under APOSR Grant F49620-96-1-0126, 'Advanced Optoelectronic Components for All-Optical Networks', we have worked to develop key technologies and components to substantially improve the performance...

Optoelectronic characterisation of an individual ZnO nanowire in contact with a micro-grid template

International Nuclear Information System (INIS)

Jiang Wei; Gao Hong; Xu Ling-Ling; Ma Jia-Ning; Zhang E; Wei Ping; Lin Jia-Qi

2011-01-01

Optoelectronic characterisation of an individual ZnO nanowire in contact with a micro-grid template has been studied. The low-cost micro-grid template made by photolithography is used to fabricate the ohmic contact metal electrodes. The current increases linearly with the bias, indicating good ohmic contacts between the nanowire and the electrodes. The resistivity of the ZnO nanowire is calculated to be 3.8 Ω·cm. We investigate the photoresponses of an individual ZnO nanowire under different light illumination using light emitting diodes (λ = 505 nm, 460 nm, 375 nm) as excitation sources in atmosphere. When individual ZnO nanowire is exposured to different light irradiation, we find that it is extremely sensitive to UV illumination; the conductance is much larger upon UV illumination than that in the dark at room temperature. This phenomenon may be related to the surface oxygen molecule adsorbtion, which indicates their potential application to the optoelectronic switching device. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Optoelectronic Devices Advanced Simulation and Analysis

CERN Document Server

Piprek, Joachim

2005-01-01

Optoelectronic devices transform electrical signals into optical signals and vice versa by utilizing the sophisticated interaction of electrons and light within micro- and nano-scale semiconductor structures. Advanced software tools for design and analysis of such devices have been developed in recent years. However, the large variety of materials, devices, physical mechanisms, and modeling approaches often makes it difficult to select appropriate theoretical models or software packages. This book presents a review of devices and advanced simulation approaches written by leading researchers and software developers. It is intended for scientists and device engineers in optoelectronics, who are interested in using advanced software tools. Each chapter includes the theoretical background as well as practical simulation results that help to better understand internal device physics. The software packages used in the book are available to the public, on a commercial or noncommercial basis, so that the interested r...

New Development of Membrane Base Optoelectronic Devices

Directory of Open Access Journals (Sweden)

Leon Hamui

2017-12-01

Full Text Available It is known that one factor that affects the operation of optoelectronic devices is the effective protection of the semiconductor materials against environmental conditions. The permeation of atmospheric oxygen and water molecules into the device structure induces degradation of the electrodes and the semiconductor. As a result, in this communication we report the fabrication of semiconductor membranes consisting of Magnesium Phthalocyanine-allene (MgPc-allene particles dispersed in Nylon 11 films. These membranes combine polymer properties with organic semiconductors properties and also provide a barrier effect for the atmospheric gas molecules. They were prepared by high vacuum evaporation and followed by thermal relaxation technique. For the characterization of the obtained membranes, Fourier-transform infrared spectroscopy (FT-IR, scanning electron microscopy (SEM, and energy dispersive spectroscopy (EDS were used to determine the chemical and microstructural properties. UV-ViS, null ellipsometry, and visible photoluminescence (PL at room temperature were used to characterize the optoelectronic properties. These results were compared with those obtained for the organic semiconductors: MgPc-allene thin films. Additionally, semiconductor membranes devices have been prepared, and a study of the device electronic transport properties was conducted by measuring electrical current density-voltage (J-V characteristics by four point probes with different wavelengths. The resistance properties against different environmental molecules are enhanced, maintaining their semiconductor functionality that makes them candidates for optoelectronic applications.

Progress in the optoelectronic analog signal transfer for high energy particle detectors

International Nuclear Information System (INIS)

Tsang, T.; Radeka, V.

1992-05-01

We report the progress in the development of a radiation hard Optoelectronic analog system to transfer particle detector signals with high accuracy. We will present the motivation of this study, the operating principle of the optoelectronic system, the system noise study, the recent R ampersand D efforts on radiation effect, temperature stability, and the realization of an integrated l x l6 optical modulator. The issue of photon source for driving such a large-scale optoelectronic modulators is a major concern. We will address this problem by examining different possible photon sources and comment on other possible alternative for signal transfer

Increased Optoelectronic Quality and Uniformity of Hydrogenated p-InP Thin Films

KAUST Repository

Wang, Hsin-Ping; Sutter-Fella, Carolin M.; Lobaccaro, Peter; Hettick, Mark; Zheng, Maxwell; Lien, Der-Hsien; Miller, D. Westley; Warren, Charles W.; Roe, Ellis T; Lonergan, Mark C; Guthrey, Harvey L.; Haegel, Nancy M.; Ager, Joel W.; Carraro, Carlo; Maboudian, Roya; He, Jr-Hau; Javey, Ali

2016-01-01

The thin-film vapor-liquid-solid (TF-VLS) growth technique presents a promising route for high quality, scalable and cost-effective InP thin films for optoelectronic devices. Towards this goal, careful optimization of material properties and device performance is of utmost interest. Here, we show that exposure of polycrystalline Zn-doped TF-VLS InP to a hydrogen plasma (in the following referred to as hydrogenation) results in improved optoelectronic quality as well as lateral optoelectronic uniformity. A combination of low temperature photoluminescence and transient photocurrent spectroscopy were used to analyze the energy position and relative density of defect states before and after hydrogenation. Notably, hydrogenation reduces the intra-gap defect density by one order of magnitude. As a metric to monitor lateral optoelectronic uniformity of polycrystalline TF-VLS InP, photoluminescence and electron beam induced current mapping reveal homogenization of the grain versus grain boundary upon hydrogenation. At the device level, we measured more than 260 TF-VLS InP solar cells before and after hydrogenation to verify the improved optoelectronic properties. Hydrogenation increased the average open-circuit voltage (VOC) of individual TF-VLS InP solar cells by up to 130 mV, and reduced the variance in VOC for the analyzed devices.

Increased Optoelectronic Quality and Uniformity of Hydrogenated p-InP Thin Films

KAUST Repository

Wang, Hsin-Ping

2016-06-08

The thin-film vapor-liquid-solid (TF-VLS) growth technique presents a promising route for high quality, scalable and cost-effective InP thin films for optoelectronic devices. Towards this goal, careful optimization of material properties and device performance is of utmost interest. Here, we show that exposure of polycrystalline Zn-doped TF-VLS InP to a hydrogen plasma (in the following referred to as hydrogenation) results in improved optoelectronic quality as well as lateral optoelectronic uniformity. A combination of low temperature photoluminescence and transient photocurrent spectroscopy were used to analyze the energy position and relative density of defect states before and after hydrogenation. Notably, hydrogenation reduces the intra-gap defect density by one order of magnitude. As a metric to monitor lateral optoelectronic uniformity of polycrystalline TF-VLS InP, photoluminescence and electron beam induced current mapping reveal homogenization of the grain versus grain boundary upon hydrogenation. At the device level, we measured more than 260 TF-VLS InP solar cells before and after hydrogenation to verify the improved optoelectronic properties. Hydrogenation increased the average open-circuit voltage (VOC) of individual TF-VLS InP solar cells by up to 130 mV, and reduced the variance in VOC for the analyzed devices.

Selecting the induction heating for normalization of deposited surfaces of cylindrical parts

Directory of Open Access Journals (Sweden)

Олена Валеріївна Бережна

2017-07-01

Full Text Available The machine parts recovered by electric contact surfacing with metal strip are characterized by high loading of the surface layer, which has a significant impact on their performance. Therefore, the improvement of the operational stability of fast-wearing machine parts through the use of combined treatment technologies is required. Not all the work-piece but just the worn zones are subjected to recovery with electric contact surfacing; the tape thickness and depth of the heat affected zone being not more than a few millimeters. Therefore, the most optimal in this case is the use of a local surface heating method of high frequency currents. This method has economical benefits because there is no need to heat the entire work-piece. The induction heating mode at a constant power density has been proposed and analytically investigated. The ratios that make it possible to determine the main heating parameters ensuring calculation of the inductor for the normalization of the reconstructed surface of cylindrical parts have been given. These parameters are: specific power, frequency and warm-up time. The proposed induction heating mode is intermediate between the quenching and cross-cutting heating and makes it possible to simultaneously obtain the required temperatures at the surface and at the predetermined depth of the heated layer of cylindrical parts with the normalization of their surfaces restored with electric contact surfacing

High bandgap III-V alloys for high efficiency optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Alberi, Kirstin; Mascarenhas, Angelo; Wanlass, Mark

2017-01-10

High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al.sub.1-xIn.sub.xP layer, and a step-grade buffer between the substrate and at least one Al.sub.1-xIn.sub.xP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al.sub.1-xIn.sub.xP is reached.

High efficiency optoelectronic terahertz sources

Science.gov (United States)

Lampin, Jean-François; Peytavit, Emilien; Akalin, Tahsin; Ducournau, G.; Hindle, Francis; Mouret, Gael

2010-08-01

We have developed a new generation of optoelectronic large bandwidth terahertz sources based on TEM horn antennas monolithically integrated with several types of photodetectors: low-temperature grown GaAs (LTG-GaAs) planar photoconductors, vertically integrated LTG-GaAs photoconductors on silicon substrate and uni-travelling-carrier photodiodes. Results of pulsed (time-domain) and photomixing (CW, frequency domain) experiments are presented.

Log-Normality and Multifractal Analysis of Flame Surface Statistics

Science.gov (United States)

Saha, Abhishek; Chaudhuri, Swetaprovo; Law, Chung K.

2013-11-01

The turbulent flame surface is typically highly wrinkled and folded at a multitude of scales controlled by various flame properties. It is useful if the information contained in this complex geometry can be projected onto a simpler regular geometry for the use of spectral, wavelet or multifractal analyses. Here we investigate local flame surface statistics of turbulent flame expanding under constant pressure. First the statistics of local length ratio is experimentally obtained from high-speed Mie scattering images. For spherically expanding flame, length ratio on the measurement plane, at predefined equiangular sectors is defined as the ratio of the actual flame length to the length of a circular-arc of radius equal to the average radius of the flame. Assuming isotropic distribution of such flame segments we convolute suitable forms of the length-ratio probability distribution functions (pdfs) to arrive at corresponding area-ratio pdfs. Both the pdfs are found to be near log-normally distributed and shows self-similar behavior with increasing radius. Near log-normality and rather intermittent behavior of the flame-length ratio suggests similarity with dissipation rate quantities which stimulates multifractal analysis. Currently at Indian Institute of Science, India.

Precise on-machine extraction of the surface normal vector using an eddy current sensor array

International Nuclear Information System (INIS)

Wang, Yongqing; Lian, Meng; Liu, Haibo; Ying, Yangwei; Sheng, Xianjun

2016-01-01

To satisfy the requirements of on-machine measurement of the surface normal during complex surface manufacturing, a highly robust normal vector extraction method using an Eddy current (EC) displacement sensor array is developed, the output of which is almost unaffected by surface brightness, machining coolant and environmental noise. A precise normal vector extraction model based on a triangular-distributed EC sensor array is first established. Calibration of the effects of object surface inclination and coupling interference on measurement results, and the relative position of EC sensors, is involved. A novel apparatus employing three EC sensors and a force transducer was designed, which can be easily integrated into the computer numerical control (CNC) machine tool spindle and/or robot terminal execution. Finally, to test the validity and practicability of the proposed method, typical experiments were conducted with specified testing pieces using the developed approach and system, such as an inclined plane and cylindrical and spherical surfaces. (paper)

Precise on-machine extraction of the surface normal vector using an eddy current sensor array

Science.gov (United States)

Wang, Yongqing; Lian, Meng; Liu, Haibo; Ying, Yangwei; Sheng, Xianjun

2016-11-01

To satisfy the requirements of on-machine measurement of the surface normal during complex surface manufacturing, a highly robust normal vector extraction method using an Eddy current (EC) displacement sensor array is developed, the output of which is almost unaffected by surface brightness, machining coolant and environmental noise. A precise normal vector extraction model based on a triangular-distributed EC sensor array is first established. Calibration of the effects of object surface inclination and coupling interference on measurement results, and the relative position of EC sensors, is involved. A novel apparatus employing three EC sensors and a force transducer was designed, which can be easily integrated into the computer numerical control (CNC) machine tool spindle and/or robot terminal execution. Finally, to test the validity and practicability of the proposed method, typical experiments were conducted with specified testing pieces using the developed approach and system, such as an inclined plane and cylindrical and spherical surfaces.

Asymptotic Normality of the Optimal Solution in Multiresponse Surface Mathematical Programming

OpenAIRE

Díaz-García, José A.; Caro-Lopera, Francisco J.

2015-01-01

An explicit form for the perturbation effect on the matrix of regression coeffi- cients on the optimal solution in multiresponse surface methodology is obtained in this paper. Then, the sensitivity analysis of the optimal solution is studied and the critical point characterisation of the convex program, associated with the optimum of a multiresponse surface, is also analysed. Finally, the asymptotic normality of the optimal solution is derived by the standard methods.

Exfoliating and Dispersing Few-Layered Graphene in Low-Boiling-Point Organic Solvents towards Solution-Processed Optoelectronic Device Applications.

Science.gov (United States)

Zhang, Lu; Miao, Zhongshuo; Hao, Zhen; Liu, Jun

2016-05-06

With normal organic surfactants, graphene can only be dispersed in water and cannot be dispersed in low-boiling-point organic solvents, which hampers its application in solution-processed organic optoelectronic devices. Herein, we report the exfoliation of graphite into graphene in low-boiling-point organic solvents, for example, methanol and acetone, by using edge-carboxylated graphene quantum dots (ECGQD) as the surfactant. The great capability of ECGQD for graphene dispersion is due to its ultralarge π-conjugated unit that allows tight adhesion on the graphene surface through strong π-π interactions, its edge-carboxylated structure that diminishes the steric effects of the oxygen-containing functional groups on the basal plane of ECGQD, and its abundance of carboxylic acid groups for solubility. The graphene dispersion in methanol enables the application of graphene:ECGQD as a cathode interlayer in polymer solar cells (PSCs). Moreover, the PSC device performance of graphene:ECGQD is better than that of Ca, the state-of-the-art cathode interlayer material. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optoelectronic and Photovoltaic Properties of the Air-Stable Organohalide Semiconductor (CH 3 NH 3 ) 3 Bi 2 I 9

KAUST Repository

Abulikemu, Mutalifu

2016-07-14

Lead halide perovskite materials have shown excellent optoelectronic as well as photovoltaic properties. However, the presence of lead and the chemical instability relegate lead halide perovskites to research applications only. Here, we investigate an emerging lead-free and air stable compound (CH3NH3)3Bi2I9 as a non-toxic potential alternative to lead halide perovskites. We have synthesized thin films, powders and millimeter-scale single crystals of (CH3NH3)3Bi2I9 and investigated their structural and optoelectronic properties. We demonstrate that the degree of crystallinity strongly affects the optoelectronic properties of the material, resulting in significantly different band gaps in polycrystalline thin films and single crystals. Surface photovoltage spectroscopy reveals outstanding photocharge generation in the visible (<700 nm), while transient absorption spectroscopy and space charge limited current measurements point to a long exciton lifetime and a high carrier mobility, respectively, similar to lead halide perovskites, pointing to the remarkable potential of this semiconductor. Photovoltaic devices fabricated using this material yield low power conversion efficiency (PCE) to date, but the PCE is expected to rise with improvements in thin film processing and device engineering.

Optoelectronics in TESLA, LHC and pi-of-the-sky experiments

CERN Document Server

Romaniuk, Ryszard; Simrock, Stefan; Wrochna, Grzegorz

2004-01-01

Optical and optoelectronics technologies are more and more widely used in the biggest world experiments of high energy and nuclear physics, as well as in the astronomy. The paper is a kind of a broad digest describing the usage of optoelectronics is such experiments and information about some of the involved teams. The described experiments include: TESLA linear accelerator and FEL, Compact Muon Solenoid at LHC and recently started pi-of-the-sky global gamma ray bursts (with associated optical flashes) observation experiment. Optoelectronics and photonics offer several key features which are either extending the technical parameters of existing solutions or adding quite new practical application possibilities. Some of these favorable features of photonic systems are: high selectivity of optical sensors, immunity to some kinds of noise processes, extremely broad bandwidth exchangeable for either terabit rate transmission or ultrashort pulse generation, parallel image processing capability, etc. The following g...

The Cellulose Nanofibers for Optoelectronic Conversion and Energy Storage

Directory of Open Access Journals (Sweden)

Yongfeng Luo

2014-01-01

Full Text Available Cellulose widely exists in plant tissues. Due to the large pores between the cellulose units, the regular paper is nontransparent that cannot be used in the optoelectronic devices. But some chemical and physical methods such as 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO oxidation can be used to improve the pores scale between the cellulose units to reach nanometer level. The cellulose nanofibers (CNFs have good mechanical strength, flexibility, thermostability, and low thermal expansion. The paper made of these nanofibers represent a kind of novel nanostructured material with ultrahigh transparency, ultrahigh haze, conductivity, biodegradable, reproducible, low pollution, environment friendly and so on. These advantages make the novel nanostructured paper apply in the optoelectronic device possible, such as electronics energy storage devices. This kind of paper is considered most likely to replace traditional materials like plastics and glass, which is attracting widespread attention, and the related research has also been reported. The purpose of this paper is to review CNFs which are applied in optoelectronic conversion and energy storage.

Optoelectronic properties of valence-state-controlled amorphous niobium oxide

Science.gov (United States)

Onozato, Takaki; Katase, Takayoshi; Yamamoto, Akira; Katayama, Shota; Matsushima, Koichi; Itagaki, Naho; Yoshida, Hisao; Ohta, Hiromichi

2016-06-01

In order to understand the optoelectronic properties of amorphous niobium oxide (a-NbO x ), we have investigated the valence states, local structures, electrical resistivity, and optical absorption of a-NbO x thin films with various oxygen contents. It was found that the valence states of Nb ion in a-NbO x films can be controlled from 5+  to 4+  by reducing oxygen pressure during film deposition at room temperature, together with changing the oxide-ion arrangement around Nb ion from Nb2O5-like to NbO2-like local structure. As a result, a four orders of magnitude reduction in the electrical resistivity of a-NbO x films was observed with decreasing oxygen content, due to the carrier generation caused by the appearance and increase of an oxygen-vacancy-related subgap state working as an electron donor. The tunable optoelectronic properties of a-NbO x films by valence-state-control with oxygen-vacancy formation will be useful for potential flexible optoelectronic device applications.

Numerical modelling of surface plasmonic polaritons

Science.gov (United States)

Mansoor, Riyadh; AL-Khursan, Amin Habbeb

2018-06-01

Extending optoelectronics into the nano-regime seems problematic due to the relatively long wavelengths of light. The conversion of light into plasmons is a possible way to overcome this problem. Plasmon's wavelengths are much shorter than that of light which enables the propagation of signals in small size components. In this paper, a 3D simulation of surface plasmon polariton (SPP) excitation is performed. The Finite integration technique was used to solve Maxwell's equations in the dielectric-metal interface. The results show how the surface plasmon polariton was generated at the grating assisted dielectric-metal interface. SPP is a good candidate for signal confinement in small size optoelectronics which allow high density optical integrated circuits in all optical networks.

Improved Topographic Normalization for Landsat TM Images by Introducing the MODIS Surface BRDF

Directory of Open Access Journals (Sweden)

Yanli Zhang

2015-05-01

Full Text Available In rugged terrain, the accuracy of surface reflectance estimations is compromised by atmospheric and topographic effects. We propose a new method to simultaneously eliminate atmospheric and terrain effects in Landsat Thematic Mapper (TM images based on a 30 m digital elevation model (DEM and Moderate Resolution Imaging Spectroradiometer (MODIS atmospheric products. Moreover, we define a normalized factor of a Bidirectional Reflectance Distribution Function (BRDF to convert the sloping pixel reflectance into a flat pixel reflectance by using the Ross Thick-Li Sparse BRDF model (Ambrals algorithm and MODIS BRDF/albedo kernel coefficient products. Sole atmospheric correction and topographic normalization were performed for TM images in the upper stream of the Heihe River Basin. The results show that using MODIS atmospheric products can effectively remove atmospheric effects compared with the Fast Line-of-Sight Atmospheric Analysis of Spectral Hypercubes (FLAASH model and the Landsat Climate Data Record (CDR. Moreover, superior topographic effect removal can be achieved by considering the surface BRDF when compared with the surface Lambertian assumption of topographic normalization.

Integrated graphene-based devices for optoelectronic applications

DEFF Research Database (Denmark)

Xiao, Sanshui

Graphene opens up for novel optoelectronic applications thanks to its high carrier mobility, ultralarge absorption bandwidth, and extremely fast material response. Here I present novel integrated grapheneplasmonic waveguide modulator showing high modulation depth, thus giving a promising way...

Standard cell-based implementation of a digital optoelectronic neural-network hardware.

Science.gov (United States)

Maier, K D; Beckstein, C; Blickhan, R; Erhard, W

2001-03-10

A standard cell-based implementation of a digital optoelectronic neural-network architecture is presented. The overall structure of the multilayer perceptron network that was used, the optoelectronic interconnection system between the layers, and all components required in each layer are defined. The design process from VHDL-based modeling from synthesis and partly automatic placing and routing to the final editing of one layer of the circuit of the multilayer perceptrons are described. A suitable approach for the standard cell-based design of optoelectronic systems is presented, and shortcomings of the design tool that was used are pointed out. The layout for the microelectronic circuit of one layer in a multilayer perceptron neural network with a performance potential 1 magnitude higher than neural networks that are purely electronic based has been successfully designed.

Tuning the optoelectronic properties of amorphous MoOx films by reactive sputtering

DEFF Research Database (Denmark)

Fernandes Cauduro, André Luis; Fabrim, Zacarias Eduardo; Ahmadpour, Mehrad

2015-01-01

In this letter, we report on the effect of oxygen partial pressure and sputtering power on amorphous DC-sputtered MoOx films. We observe abrupt changes in the optoelectronic properties of the reported films by increasing the oxygen partial pressure from 1.00 ? 10?3 mbar to 1.37 ? 10?3 mbar during...... significantly the microstructure of the studied films. The presence of states within the band gap due to the lack of oxygen is the most probable mechanism for generat- ing a change in electrical conductivity as well as optical absorption in DC-sputtered MoOx. The large tuning range of the optoelectronic...... properties in these films holds strong promise for their implementation in optoelectronic devices....

Progress in complementary metal–oxide–semiconductor silicon photonics and optoelectronic integrated circuits

International Nuclear Information System (INIS)

Chen Hongda; Zhang Zan; Huang Beiju; Mao Luhong; Zhang Zanyun

2015-01-01

Silicon photonics is an emerging competitive solution for next-generation scalable data communications in different application areas as high-speed data communication is constrained by electrical interconnects. Optical interconnects based on silicon photonics can be used in intra/inter-chip interconnects, board-to-board interconnects, short-reach communications in datacenters, supercomputers and long-haul optical transmissions. In this paper, we present an overview of recent progress in silicon optoelectronic devices and optoelectronic integrated circuits (OEICs) based on a complementary metal–oxide–semiconductor-compatible process, and focus on our research contributions. The silicon optoelectronic devices and OEICs show good characteristics, which are expected to benefit several application domains, including communication, sensing, computing and nonlinear systems. (review)

Normal Contacts of Lubricated Fractal Rough Surfaces at the Atomic Scale

NARCIS (Netherlands)

Solhjoo, Soheil; Vakis, Antonis I.

The friction of contacting interfaces is a function of surface roughness and applied normal load. Under boundary lubrication, this frictional behavior changes as a function of lubricant wettability, viscosity, and density, by practically decreasing the possibility of dry contact. Many studies on

Near surface silicide formation after off-normal Fe-implantation of Si(001) surfaces

Energy Technology Data Exchange (ETDEWEB)

Khanbabaee, B., E-mail: khanbabaee@physik.uni-siegen.de; Pietsch, U. [Solid State Physics, University of Siegen, D-57068 Siegen (Germany); Lützenkirchen-Hecht, D. [Fachbereich C - Physik, Bergische Universität Wuppertal, D-42097 Wuppertal (Germany); Hübner, R.; Grenzer, J.; Facsko, S. [Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany)

2014-07-14

We report on formation of non-crystalline Fe-silicides of various stoichiometries below the amorphized surface of crystalline Si(001) after irradiation with 5 keV Fe{sup +} ions under off-normal incidence. We examined samples prepared with ion fluences of 0.1 × 10{sup 17} and 5 × 10{sup 17} ions cm{sup −2} exhibiting a flat and patterned surface morphology, respectively. Whereas the iron silicides are found across the whole surface of the flat sample, they are concentrated at the top of ridges at the rippled surface. A depth resolved analysis of the chemical states of Si and Fe atoms in the near surface region was performed by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy (XAS) using synchrotron radiation. The chemical shift and the line shape of the Si 2p core levels and valence bands were measured and associated with the formation of silicide bonds of different stoichiometric composition changing from an Fe-rich silicides (Fe{sub 3}Si) close to the surface into a Si-rich silicide (FeSi{sub 2}) towards the inner interface to the Si(001) substrate. This finding is supported by XAS analysis at the Fe K-edge which shows changes of the chemical environment and the near order atomic coordination of the Fe atoms in the region close to surface. Because a similar Fe depth profile has been found for samples co-sputtered with Fe during Kr{sup +} ion irradiation, our results suggest the importance of chemically bonded Fe in the surface region for the process of ripple formation.

Optoelectronic and nonlinear optical processes in low dimensional ...

Indian Academy of Sciences (India)

Optoelectronic process; nonlinear optical process; semiconductor. Quest for ever faster and intelligent information processing technologies has sparked ..... Schematic energy level diagram for the proposed 4-level model. States other than the.

Monocrystalline halide perovskite nanostructures for optoelectronic applications

NARCIS (Netherlands)

Khoram, P.

2018-01-01

Halide perovskites are a promising class of materials for incorporation in optoelectronics with higher efficiency and lower cost. The solution processability of these materials provides unique opportunities for simple nanostructure fabrication. In the first half of the thesis (chapter 2 and 3) we

Cell-surface glycoproteins of human sarcomas: differential expression in normal and malignant tissues and cultured cells

International Nuclear Information System (INIS)

Rettig, W.F.; Garin-Chesa, P.; Beresford, H.R.; Oettgen, H.F.; Melamed, M.R.; Old, L.J.

1988-01-01

Normal differentiation and malignant transformation of human cells are characterized by specific changes in surface antigen phenotype. In the present study, the authors have defined six cell-surface antigens of human sarcomas and normal mesenchymal cells, by using mixed hemadsorption assays and immunochemical methods for the analysis of cultured cells and immunohistochemical staining for the analysis of normal tissues and > 200 tumor specimens. Differential patterns of F19, F24, G171, G253, S5, and Thy-1 antigen expression were found to characterize (i) subsets of cultured sarcoma cell lines, (ii) cultured fibroblasts derived from various organs, (iii) normal resting and activated mesenchymal tissues, and (iv) sarcoma and nonmesenchymal tumor tissues. These results provide a basic surface antigenic map for cultured mesenchymal cells and mesenchymal tissues and permit the classification of human sarcomas according to their antigenic phenotypes

Laser assisted fabrication of random rough surfaces for optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Brissonneau, V., E-mail: vincent.brissonneau@im2np.fr [Thales Optronique SA, Avenue Gay-Lussac, 78995 Elancourt (France); Institut Materiaux Microelectronique Nanosciences de Provence, Aix Marseille Universite, Avenue Escadrille Normandie Niemen, 13397 Marseille (France); Escoubas, L. [Institut Materiaux Microelectronique Nanosciences de Provence, Aix Marseille Universite, Avenue Escadrille Normandie Niemen, 13397 Marseille (France); Flory, F. [Institut Materiaux Microelectronique Nanosciences de Provence, Ecole Centrale Marseille, Marseille (France); Berginc, G. [Thales Optronique SA, Avenue Gay-Lussac, 78995 Elancourt (France); Maire, G.; Giovannini, H. [Institut Fresnel, Aix Marseille Universite, Avenue Escadrille Normandie Niemen, 13397 Marseille (France)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Random rough surfaces are photofabricated using an argon ion laser. Black-Right-Pointing-Pointer Speckle and surface correlation function are linked. Black-Right-Pointing-Pointer Exposure beam is modified allowing tuning the correlation. Black-Right-Pointing-Pointer Theoretical examples are presented. Black-Right-Pointing-Pointer Experimental results are compared with theoretical expectation. - Abstract: Optical surface structuring shows great interest for antireflective or scattering properties. Generally, fabricated surface structures are periodical but random surfaces that offer new degrees of freedom and possibilities by the control of their statistical properties. We propose an experimental method to create random rough surfaces on silicon by laser processing followed by etching. A photoresist is spin coated onto a silicon substrate and then exposed to the scattering of a modified laser beam. The beam modification is performed by using a micromirror matrix allowing laser beam shaping. An example of tuning is presented. An image composed of two white circles with a black background is displayed and the theoretical shape of the correlation is calculated. Experimental surfaces are elaborated and the correlation function calculated from height mapping. We finally compared the experimental and theoretical correlation functions.

Research on the processing technology of medium-caliber aspheric lens in the optoelectronic integrated test system

Science.gov (United States)

Liu, Dan; Yu, Xin-ying; Wang, Wei

2016-10-01

In the optoelectronic integrated test system, surface profile and finish of the optical element are put forward higher request. Taking an aspherical quartz glass lens with a diameter of 200mm as example, taking Preston hypothesis as the theoretical basis, analyze the influence of surface quality of various process parameters, including the workpiece and the tool axis spindle speed, wheel type, concentration polishing, polishing mold species, dwell time, polishing pressure and other parameters. Using CNC method for the surface profile and surface quality of the lens were investigated. Taking profilometer measurement results as a guide, by testing and simulation analysis, process parameters were improved constantly in the process of manufacturing. Mid and high frequency error were trimmed and improved so that the surface form gradually converged to the required accuracy. The experimental results show that the final accuracy of the surface is less than 2µm and the surface finish is, which fulfils the accuracy requirement of aspherical focusing lens in optical system.

Modelling of optoelectronic circuits based on resonant tunneling diodes

Science.gov (United States)

Rei, João. F. M.; Foot, James A.; Rodrigues, Gil C.; Figueiredo, José M. L.

2017-08-01

Resonant tunneling diodes (RTDs) are the fastest pure electronic semiconductor devices at room temperature. When integrated with optoelectronic devices they can give rise to new devices with novel functionalities due to their highly nonlinear properties and electrical gain, with potential applications in future ultra-wide-band communication systems (see e.g. EU H2020 iBROW Project). The recent coverage on these devices led to the need to have appropriated simulation tools. In this work, we present RTD based optoelectronic circuits simulation packages to provide circuit signal level analysis such as transient and frequency responses. We will present and discuss the models, and evaluate the simulation packages.

Basic opto-electronics on silicon for sensor applications

NARCIS (Netherlands)

Joppe, J.L.; Bekman, H.H.P.Th.; de Krijger, A.J.T.; Albers, H.; Chalmers, J.; Chalmers, J.D.; Holleman, J.; Ikkink, T.J.; Ikkink, T.; van Kranenburg, H.; Zhou, M.-J.; Zhou, Ming-Jiang; Lambeck, Paul

1994-01-01

A general platform for integrated opto-electronic sensor systems on silicon is proposed. The system is based on a hybridly integrated semiconductor laser, ZnO optical waveguides and monolithic photodiodes and electronic circuiry.

77 FR 65713 - Certain Optoelectronic Devices for Fiber Optic Communications, Components Thereof, and Products...

Science.gov (United States)

2012-10-30

... Fiber Optic Communications, Components Thereof, and Products Containing the Same; Notice of Institution... certain optoelectronic devices for fiber optic communications, components thereof, and products containing... optoelectronic devices for fiber optic communications, components thereof, and products containing the same that...

Surface Restructuring of Hybrid Perovskite Crystals

KAUST Repository

Banavoth, Murali

2016-11-07

Hybrid perovskite crystals have emerged as an important class of semiconductors because of their remarkable performance in optoelectronics devices. The interface structure and chemistry of these crystals are key determinants of the device\\'s performance. Unfortunately, little is known about the intrinsic properties of the surfaces of perovskite materials because extrinsic effects, such as complex microstructures, processing conditions, and hydration under ambient conditions, are thought to cause resistive losses and high leakage current in solar cells. We reveal the intrinsic structural and optoelectronic properties of both pristinely cleaved and aged surfaces of single crystals. We identify surface restructuring on the aged surfaces (visualized on the atomic-scale by scanning tunneling microscopy) that lead to compositional and optical bandgap changes as well as degradation of carrier dynamics, photocurrent, and solar cell device performance. The insights reported herein clarify the key variables involved in the performance of perovskite-based solar cells and fabrication of high-quality surface single crystals, thus paving the way toward their future exploitation in highly efficient solar cells.

Renal function maturation in children: is normalization to surface area valid?

International Nuclear Information System (INIS)

Rutland, M.D.; Hassan, I.M.; Que, L.

1999-01-01

Full text: Gamma camera DTPA renograms were analysed to measure renal function by the rate at which the kidneys took up tracer from the blood. This was expressed either directly as the fractional uptake rate (FUR), which is not related to body size, or it was converted to a camera-based GFR by the formula GFR blood volume x FUR, and this GFR was normalized to a body surface area of 1.73 m2. Most of the patients studied had one completely normal kidney, and one kidney with reflux but normal function and no large scars. The completely normal kidneys contributed, on average, 50% of the total renal function. The results were considered in age bands, to display the effect of age on renal function. The camera-GFR measurements showed the conventional results of poor renal function in early childhood, with a slow rise to near-adult values by the age of 2 years, and somewhat low values throughout childhood. The uptake values showed a different pattern, with renal function rising to adult equivalent values by the age of 4 months, and with children having better renal function than adults throughout most of their childhood. The standard deviations expressed as coefficients of variation (CV) were smaller for the FUR technique than the GFR (Wilcoxon rank test, P < 0.01). These results resemble recent published measurements of absolute DMSA uptake, which are also unrelated to body size and show early renal maturation. The results also suggest that the reason children have lower serum creatinine levels than adults is that they have better renal function. If this were confirmed, it would raise doubts about the usefulness of normalizing renal function to body surface area in children

Determination of Optimum Viewing Angles for the Angular Normalization of Land Surface Temperature over Vegetated Surface

Directory of Open Access Journals (Sweden)

Huazhong Ren

2015-03-01

Full Text Available Multi-angular observation of land surface thermal radiation is considered to be a promising method of performing the angular normalization of land surface temperature (LST retrieved from remote sensing data. This paper focuses on an investigation of the minimum requirements of viewing angles to perform such normalizations on LST. The normally kernel-driven bi-directional reflectance distribution function (BRDF is first extended to the thermal infrared (TIR domain as TIR-BRDF model, and its uncertainty is shown to be less than 0.3 K when used to fit the hemispheric directional thermal radiation. A local optimum three-angle combination is found and verified using the TIR-BRDF model based on two patterns: the single-point pattern and the linear-array pattern. The TIR-BRDF is applied to an airborne multi-angular dataset to retrieve LST at nadir (Te-nadir from different viewing directions, and the results show that this model can obtain reliable Te-nadir from 3 to 4 directional observations with large angle intervals, thus corresponding to large temperature angular variations. The Te-nadir is generally larger than temperature of the slant direction, with a difference of approximately 0.5~2.0 K for vegetated pixels and up to several Kelvins for non-vegetated pixels. The findings of this paper will facilitate the future development of multi-angular thermal infrared sensors.

The Role of Surface Tension in the Crystallization of Metal Halide Perovskites

KAUST Repository

Zhumekenov, Ayan A.

2017-07-06

The exciting intrinsic properties discovered in single crystals of metal halide perovskites still await their translation into optoelectronic devices. The poor understanding and control of the crystallization process of these materials are current bottlenecks retarding the shift towards single crystal-based optoelectronics. Here we theoretically and experimentally elucidate the role of surface tension in the rapid synthesis of perovskite single crystals by inverse temperature crystallization (ITC). Understanding the nucleation and growth mechanisms enabled us to exploit surface tension to direct the growth of monocrystalline films of perovskites (AMX3, where A = CH3NH3+ or MA; M = Pb2+, Sn2+; X = Br-, I-) on the solution surface. We achieve up to 1 cm2-sized monocrystalline films with thickness on the order of the charge carrier diffusion length (~5-10 µm). Our work paves the way to control the crystallization process of perovskites, including thin film deposition, which is essential to advance the performance benchmarks of perovskite optoelectronics.

Optoelectronic properties of higher acenes, their BN analogue and substituted derivatives

International Nuclear Information System (INIS)

Armaković, Stevan; Armaković, Sanja J.; Holodkov, Vladimir; Pelemiš, Svetlana

2016-01-01

We have investigated optoelectronic properties of higher acenes: pentacene, hexacene, heptacene, octacene, nonacene, decacene and their boron-nitride (BN) analogues, within the framework of density functional theory (DFT). We have also investigated the optoelectronic properties of acenes modified by BN substitution. Calculated optoelectronic properties encompasses: oxidation and reduction potentials, electron and hole reorganization energies and energy difference between excited first singlet and triplet states ΔE(S_1−T_1). Oxidation and reduction potentials indicate significantly better stability of BN analogues, comparing with their all-carbon relatives. Although higher acenes possess lower electron and hole reorganization energies, with both best values much lower than 0.1 eV, their BN analogues also have competitive values of reorganization energies, especially for holes for which reorganization energy is also lower than 0.1 eV. On the other hand ΔE(S_1−T_1) is much better for BN analogues, having values that indicate that BN analogues are possible applicable for thermally activated delayed fluorescence. - Highlights: • Optoelectronic properties of structures based on higher acenes have been investigated. • Oxidation and reduction potentials together with reorganization energies are calculated. • TADF is analyzed through calculation of ΔE(S_1−T_1), which is much better for BN analogues. • Reorganization energies of acenes improve with the increase of number of benzene rings.

Enhancing electronic and optoelectronic performances of tungsten diselenide by plasma treatment.

Science.gov (United States)

Xie, Yuan; Wu, Enxiu; Hu, Ruixue; Qian, Shuangbei; Feng, Zhihong; Chen, Xuejiao; Zhang, Hao; Xu, Linyan; Hu, Xiaodong; Liu, Jing; Zhang, Daihua

2018-06-21

Transition metal dichalcogenides (TMDCs) have recently become spotlighted as nanomaterials for future electronic and optoelectronic devices. In this work, we develop an effective approach to enhance the electronic and optoelectronic performances of WSe2-based devices by N2O plasma treatment. The hole mobility and sheet density increase by 2 and 5 orders of magnitude, reaching 110 cm2 V-1 s-1 and 2.2 × 1012 cm-2, respectively, after the treatment. At the same time, the contact resistance (Rc) between WSe2 and its metal electrode drop by 5 orders of magnitude from 1.0 GΩ μm to 28.4 kΩ μm. The WSe2 photoconductor exhibits superior performance with high responsivity (1.5 × 105 A W-1), short response time (106). We have also built a lateral p-n junction on a single piece of WSe2 flake by selective plasma exposure. The junction reaches an exceedingly high rectifying ratio of 106, an excellent photoresponsivity of 2.49 A W-1 and a fast response of 8 ms. The enhanced optoelectronic performance is attributed to band-engineering through the N2O plasma treatment, which can potentially serve as an effective and versatile approach for device engineering and optimization in a wide range of electronic and optoelectronic devices based on 2D materials.

Sintering effect on the optoelectronic characteristics of HgSe nanoparticle films on plastic substrates

International Nuclear Information System (INIS)

Byun, Kwangsub; Cho, Kyoungah; Kim, Sangsig

2010-01-01

The optoelectronic characteristics of HgSe nanoparticle films spin-coated on flexible plastic substrates are investigated under the illumination of 1.3 μm wavelength light. The sintering process improves the optoelectronic characteristics of the HgSe nanoparticle films. The photocurrent of the sintered HgSe nanoparticle films under the illumination of 1.3 μm wavelength light is approximately 20 times larger in magnitude than that of the non-sintered films in air at room temperature. Moreover, the endurance of the flexible optoelectronic device investigated by the continuous substrate bending test reveals that the photocurrent efficiency changes negligibly up to 250 cycles.

Optoelectronic Characterization of Infrared Photodetector Fabricated on Ge-on-Si Substrate.

Science.gov (United States)

Khurelbaatar, Zagarzusem; Kil, Yeon-Ho; Kim, Taek Sung; Shim, Kyu-Hwan; Hong, Hyobong; Choi, Chel-Jong

2015-10-01

We report on the optoelectronic characterization of Ge p-i-n infrared photodetector fabricated on Ge-on-Si substrate using rapid thermal chemical vapor deposition (RTCVD). The phosphorous doping concentration and the root mean square (RMS) surface roughness of epitaxial layer was estimated to be 2 x 10(18) cm(-3) and 1.2 nm, respectively. The photodetector were characterized with respect to their dark, photocurrent and responsivities in the wavelength range of 1530-1630 nm. At 1550 nm wavelength, responsivity of 0.32 A/W was measured for a reverse bias of 1 V, corresponding to 25% external quantum efficiency, without an optimal antireflection coating. Responsivity drastically reduced from 1560 nm wavelength which could be attributed to decreased absorption of Ge at room temperature.

CuPc/C60 heterojunction thin film optoelectronic devices

International Nuclear Information System (INIS)

Murtaza, Imran; Karimov, Khasan S.; Qazi, Ibrahim

2010-01-01

The optoelectronic properties of heterojunction thin film devices with ITO/CuPc/C 60 /Al structure have been investigated by analyzing their current-voltage characteristics, optical absorption and photocurrent. In this organic photovoltaic device, CuPc acts as an optically active layer, C 60 as an electron-transporting layer and ITO and Al as electrodes. It is observed that, under illumination, excitons are formed, which subsequently drift towards the interface with C 60 , where an internal electric field is present. The excitons that reach the interface are subsequently dissociated into free charge carriers due to the electric field present at the interface. The experimental results show that in this device the total current density is a function of injected carriers at the electrode-organic semiconductor surface, the leakage current through the organic layer and collected photogenerated current that results from the effective dissociation of excitons. (semiconductor devices)

Studying the influence of substrate conductivity on the optoelectronic properties of quantum dots langmuir monolayer

Science.gov (United States)

Al-Alwani, Ammar J.; Chumakov, A. S.; Begletsova, N. N.; Shinkarenko, O. A.; Markin, A. V.; Gorbachev, I. A.; Bratashov, D. N.; Gavrikov, M. V.; Venig, S. B.; Glukhovskoy, E. G.

2018-04-01

The formation of CdSe quantum dots (QDs) monolayers was studied by Langmuir Blodgett method. The fluorescence (PL) spectra of QD monolayers were investigated at different substrate type (glass, silicon and ITO glass) and the influence of graphene sheets layer (as a conductive surface) on the QDs properties has also been studied. The optoelectronic properties of QDs can be tuned by deposition of insulating nano-size layers of the liquid crystal between QDs and conductive substrate. The monolayer of QDs transferred on conductive surface (glass with ITO) has lowest intensity of PL spectra due to quenching effect. The PL intensity of QDs could be tuned by using various type of substrates or/and by transformed high conductive layer. Also the photooxidation processes of CdSe QDs monolayer on the solid surface can be controlled by selection of suitable substrate. The current-voltage (I–V) characteristics of QDs thin film on ITO surface was studied using scanning tunneling microscope (STM).

Optoelectronic properties of higher acenes, their BN analogue and substituted derivatives

Energy Technology Data Exchange (ETDEWEB)

Armaković, Stevan, E-mail: stevan.armakovic@df.uns.ac.rs [University of Novi Sad, Faculty of Sciences, Department of Physics, Trg Dositeja Obradovića 4, 21000, Novi Sad (Serbia); Armaković, Sanja J. [University of Novi Sad, Faculty of Sciences, Department of Chemistry, Biochemistry and Environmental Protection, Trg Dositeja Obradovića 3, 21000, Novi Sad (Serbia); Holodkov, Vladimir [Educons University, Faculty of Sport and Tourism - TIMS, Radnička 30a, 21000, Novi Sad (Serbia); Pelemiš, Svetlana [University of East Sarajevo, Faculty of Technology, Karakaj bb, 75400, Zvornik, Republic of Srpska, Bosnia and Herzegovina (Bosnia and Herzegovina)

2016-02-15

We have investigated optoelectronic properties of higher acenes: pentacene, hexacene, heptacene, octacene, nonacene, decacene and their boron-nitride (BN) analogues, within the framework of density functional theory (DFT). We have also investigated the optoelectronic properties of acenes modified by BN substitution. Calculated optoelectronic properties encompasses: oxidation and reduction potentials, electron and hole reorganization energies and energy difference between excited first singlet and triplet states ΔE(S{sub 1}−T{sub 1}). Oxidation and reduction potentials indicate significantly better stability of BN analogues, comparing with their all-carbon relatives. Although higher acenes possess lower electron and hole reorganization energies, with both best values much lower than 0.1 eV, their BN analogues also have competitive values of reorganization energies, especially for holes for which reorganization energy is also lower than 0.1 eV. On the other hand ΔE(S{sub 1}−T{sub 1}) is much better for BN analogues, having values that indicate that BN analogues are possible applicable for thermally activated delayed fluorescence. - Highlights: • Optoelectronic properties of structures based on higher acenes have been investigated. • Oxidation and reduction potentials together with reorganization energies are calculated. • TADF is analyzed through calculation of ΔE(S{sub 1}−T{sub 1}), which is much better for BN analogues. • Reorganization energies of acenes improve with the increase of number of benzene rings.

Recent advances in flexible and wearable organic optoelectronic devices

Science.gov (United States)

Zhu, Hong; Shen, Yang; Li, Yanqing; Tang, Jianxin

2018-01-01

Flexible and wearable optoelectronic devices have been developing to a new stage due to their unique capacity for the possibility of a variety of wearable intelligent electronics, including bendable smartphones, foldable touch screens and antennas, paper-like displays, and curved and flexible solid-state lighting devices. Before extensive commercial applications, some issues still have to be solved for flexible and wearable optoelectronic devices. In this regard, this review concludes the newly emerging flexible substrate materials, transparent conductive electrodes, device architectures and light manipulation methods. Examples of these components applied for various kinds of devices are also summarized. Finally, perspectives about the bright future of flexible and wearable electronic devices are proposed. Project supported by the Ministry of Science and Technology of China (No. 2016YFB0400700).

Transferable, conductive TiO{sub 2} nanotube membranes for optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Liu, Guohua [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway); Chen, Ting [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Sun, Yunlan; Chen, Guang [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Wang, Kaiying, E-mail: Kaiying.Wang@hbv.no [Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway)

2014-08-30

Graphical abstract: An optoelectronic device with vertical architecture offers straight conducting filaments for electron transportation. - Highlights: • Highly porous TiO{sub 2} nanotube membranes are prepared by two-step anodization. • An optoelectronic device is integrated with photocurrent transportation along the nanotube axial. • Straight conducting nano-filaments are beneficial for electron transportation. • Photoconductive performances are demonstrated under front/back-illumination. - Abstract: We report a facile approach for preparing free-standing and crystalline TiO{sub 2} nanotube membranes (TNMs) by taking advantage of differential mechanical stress between two anodic layers. The membrane exhibits visible light transmittance (∼40%) and UV absorption (∼99%) with good flexibility, which is favorable to integrate with substrates in optoelectronics. A sandwich-type device is assembled through stacking the membrane and substrates. The dependence of current-perpendicular-to-membrane vs applied voltage shows a remarkable photoconductive performance for both front and back illumination. The photocurrent value increases ∼2 or 3 orders magnitude under UV light radiation as compared to that in darkness. The photoresponse is arisen from high internal gain caused by hole trapping along the nanotube walls. This work is crucial for understanding intrinsic optical properties of nanostructured membranes.

Electron microscopy study of advanced heterostructures for optoelectronics

NARCIS (Netherlands)

Katcki, J.; Ratajczak, J.; Phillipp, F.; Muszalski, J.; Bugajski, M.; Chen, J.X.; Fiore, A.

2003-01-01

The application of cross-sectional transmission electron microscopy and SEM to the investigation of optoelectronic devices are reviewed. Special attention was paid to the electron microscopy assessment of the growth perfection of such crucial elements of the devices like quantum wells, quantum dots,

Optoelectronics-related competence building in Japanese and Western firms

Science.gov (United States)

Miyazaki, Kumiko

1992-05-01

In this paper, an analysis is made of how different firms in Japan and the West have developed competence related to optoelectronics on the basis of their previous experience and corporate strategies. The sample consists of a set of seven Japanese and four Western firms in the industrial, consumer electronics and materials sectors. Optoelectronics is divided into subfields including optical communications systems, optical fibers, optoelectronic key components, liquid crystal displays, optical disks, and others. The relative strengths and weaknesses of companies in the various subfields are determined using the INSPEC database, from 1976 to 1989. Parallel data are analyzed using OTAF U.S. patent statistics and the two sets of data are compared. The statistical analysis from the database is summarized for firms in each subfield in the form of an intra-firm technology index (IFTI), a new technique introduced to assess the revealed technology advantage of firms. The quantitative evaluation is complemented by results from intensive interviews with the management and scientists of the firms involved. The findings show that there is a marked variation in the way firms' technological trajectories have evolved giving rise to strength in some and weakness in other subfields for the different companies, which are related to their accumulated core competencies, previous core business activities, organizational, marketing, and competitive factors.

A whole-process progressive training mode to foster optoelectronic students' innovative practical ability

Science.gov (United States)

Zhong, Hairong; Xu, Wei; Hu, Haojun; Duan, Chengfang

2017-08-01

This article analyzes the features of fostering optoelectronic students' innovative practical ability based on the knowledge structure of optoelectronic disciplines, which not only reveals the common law of cultivating students' innovative practical ability, but also considers the characteristics of the major: (1) The basic theory is difficult, and the close combination of science and technology is obvious; (2)With the integration of optics, mechanics, electronics and computer, the system technology is comprehensive; (3) It has both leading-edge theory and practical applications, so the benefit of cultivating optoelectronic students is high ; (4) The equipment is precise and the practice is costly. Considering the concept and structural characteristics of innovative and practical ability, and adhering to the idea of running practice through the whole process, we put forward the construction of three-dimensional innovation and practice platform which consists of "Synthetically Teaching Laboratory + Innovation Practice Base + Scientific Research Laboratory + Major Practice Base + Joint Teaching and Training Base", and meanwhile build a whole-process progressive training mode to foster optoelectronic students' innovative practical ability, following the process of "basic experimental skills training - professional experimental skills training - system design - innovative practice - scientific research project training - expanded training - graduation project": (1) To create an in - class practical ability cultivation environment that has distinctive characteristics of the major, with the teaching laboratory as the basic platform; (2) To create an extra-curricular innovation practice activities cultivation environment that is closely linked to the practical application, with the innovation practice base as a platform for improvement; (3) To create an innovation practice training cultivation environment that leads the development of cutting-edge, with the scientific

Noninvasive Optoelectronic Assessment of Induced Sagittal Imbalance Using the Vicon System.

Science.gov (United States)

Ould-Slimane, Mourad; Latrobe, Charles; Michelin, Paul; Chastan, Nathalie; Dujardin, Franck; Roussignol, Xavier; Gauthé, Rémi

2017-06-01

Spinal diseases often induce gait disorders with multifactorial origins such as lumbar pain, radicular pain, neurologic complications, or spinal deformities. However, radiography does not permit an analysis of spinal dynamics; therefore, sagittal balance dynamics during gait remain largely unexplored. This prospective and controlled pilot study assessed the Vicon system for detecting sagittal spinopelvic imbalance, to determine the correlations between optoelectronic and radiographic parameters. Reversible anterior sagittal imbalance was induced in 24 healthy men using a thoracolumbar corset. Radiographic, optoelectronic, and comparative analyses were conducted. Corset wearing induced significant variations in radiographic parameters indicative of imbalance; the mean C7-tilt and d/D ratio increased by 15° ± 7.4° and 359%, respectively, whereas the mean spinosacral angle decreased by 16.8° ± 8° (all P imbalance; the mean spinal angle increased by 15.4° ± 5.6° (P imbalance detected using the Vicon system. Optoelectronic C7'S1' correlated with radiographic C7-tilt and d/D ratio. Copyright © 2017 Elsevier Inc. All rights reserved.

Optical and Optoelectronic Property Analysis of Nanomaterials inside Transmission Electron Microscope.

Science.gov (United States)

Fernando, Joseph F S; Zhang, Chao; Firestein, Konstantin L; Golberg, Dmitri

2017-12-01

In situ transmission electron microscopy (TEM) allows one to investigate nanostructures at high spatial resolution in response to external stimuli, such as heat, electrical current, mechanical force and light. This review exclusively focuses on the optical, optoelectronic and photocatalytic studies inside TEM. With the development of TEMs and specialized TEM holders that include in situ illumination and light collection optics, it is possible to perform optical spectroscopies and diverse optoelectronic experiments inside TEM with simultaneous high resolution imaging of nanostructures. Optical TEM holders combining the capability of a scanning tunneling microscopy probe have enabled nanomaterial bending/stretching and electrical measurements in tandem with illumination. Hence, deep insights into the optoelectronic property versus true structure and its dynamics could be established at the nanometer-range precision thus evaluating the suitability of a nanostructure for advanced light driven technologies. This report highlights systems for in situ illumination of TEM samples and recent research work based on the relevant methods, including nanomaterial cathodoluminescence, photoluminescence, photocatalysis, photodeposition, photoconductivity and piezophototronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An opto-electronic joint detection system based on DSP aiming at early cervical cancer screening

Science.gov (United States)

Wang, Weiya; Jia, Mengyu; Gao, Feng; Yang, Lihong; Qu, Pengpeng; Zou, Changping; Liu, Pengxi; Zhao, Huijuan

2015-02-01

The cervical cancer screening at a pre-cancer stage is beneficial to reduce the mortality of women. An opto-electronic joint detection system based on DSP aiming at early cervical cancer screening is introduced in this paper. In this system, three electrodes alternately discharge to the cervical tissue and three light emitting diodes in different wavelengths alternately irradiate the cervical tissue. Then the relative optical reflectance and electrical voltage attenuation curve are obtained by optical and electrical detection, respectively. The system is based on DSP to attain the portable and cheap instrument. By adopting the relative reflectance and the voltage attenuation constant, the classification algorithm based on Support Vector Machine (SVM) discriminates abnormal cervical tissue from normal. We use particle swarm optimization to optimize the two key parameters of SVM, i.e. nuclear factor and cost factor. The clinical data were collected on 313 patients to build a clinical database of tissue responses under optical and electrical stimulations with the histopathologic examination as the gold standard. The classification result shows that the opto-electronic joint detection has higher total coincidence rate than separate optical detection or separate electrical detection. The sensitivity, specificity, and total coincidence rate increase with the increasing of sample numbers in the training set. The average total coincidence rate of the system can reach 85.1% compared with the histopathologic examination.

Tuning optoelectronic properties of small semiconductor nanocrystals through surface ligand chemistry

Science.gov (United States)

Lawrence, Katie N.

Semiconductor nanocrystals (SNCs) are a class of material with one dimension wave function 1) into the ligand monolayer using metal carboxylates and 2) beyond the ligand monolayer to provide strong inter-SNC electronic coupling using poly(ethylene) glycol (PEG)-thiolate was explored. Passivation of the Se sites of metal chalcogenide SNCs by metal carboxylates provided a two-fold outcome: (1) facilitating the delocalization of exciton wave functions into ligand monolayers (through appropriate symmetry matching and energy alignment) and (2) increasing fluorescence quantum yield (through passivation of midgap trap states). An ˜240 meV red-shift in absorbance was observed upon addition of Cd(O2CPh)2, as well as a ˜260 meV shift in emission with an increase in PL-QY to 73%. Through a series of control experiments, as well as full reversibility of our system, we were able to conclude that the observed bathochromic shifts were the sole consequence of delocalization, not a change in size or relaxation of the inorganic core, as previously reported. Furthermore, the outstanding increase in PL-QY was found to be a product of both passivation and delocalization effects. Next we used poly(ethylene) glycol (PEG)-thiolate ligands to passivate the SNC and provide unique solubility properties in both aqueous and organic solvents as well as utilized their highly conductive nature to explore inter-SNC electronic coupling. The electronic coupling was studied: 1) as a function of SNC size where the smallest SNC exhibited the largest coupling energy (170 meV) and 2) as a function of annealing temperature, where an exceptionally large (˜400 meV) coupling energy was observed. This strong electronic coupling in self-organized films could facilitate the large-scale production of highly efficient electronic materials for advanced optoelectronic device applications. Strong inter-SNC electronic coupling together with high solubility, such as that provided by PEG-thiolate-coated CdSe SNCs

Dynamics of an optically confined nanoparticle diffusing normal to a surface.

Science.gov (United States)

Schein, Perry; O'Dell, Dakota; Erickson, David

2016-06-01

Here we measure the hindered diffusion of an optically confined nanoparticle in the direction normal to a surface, and we use this to determine the particle-surface interaction profile in terms of the absolute height. These studies are performed using the evanescent field of an optically excited single-mode silicon nitride waveguide, where the particle is confined in a height-dependent potential energy well generated from the balance of optical gradient and surface forces. Using a high-speed cmos camera, we demonstrate the ability to capture the short time-scale diffusion dominated motion for 800-nm-diam polystyrene particles, with measurement times of only a few seconds per particle. Using established theory, we show how this information can be used to estimate the equilibrium separation of the particle from the surface. As this measurement can be made simultaneously with equilibrium statistical mechanical measurements of the particle-surface interaction energy landscape, we demonstrate the ability to determine these in terms of the absolute rather than relative separation height. This enables the comparison of potential energy landscapes of particle-surface interactions measured under different experimental conditions, enhancing the utility of this technique.

Cultivation of students' engineering designing ability based on optoelectronic system course project

Science.gov (United States)

Cao, Danhua; Wu, Yubin; Li, Jingping

2017-08-01

We carry out teaching based on optoelectronic related course group, aiming at junior students majored in Optoelectronic Information Science and Engineering. " Optoelectronic System Course Project " is product-designing-oriented and lasts for a whole semester. It provides a chance for students to experience the whole process of product designing, and improve their abilities to search literature, proof schemes, design and implement their schemes. In teaching process, each project topic is carefully selected and repeatedly refined to guarantee the projects with the knowledge integrity, engineering meanings and enjoyment. Moreover, we set up a top team with professional and experienced teachers, and build up learning community. Meanwhile, the communication between students and teachers as well as the interaction among students are taken seriously in order to improve their team-work ability and communicational skills. Therefore, students are not only able to have a chance to review the knowledge hierarchy of optics, electronics, and computer sciences, but also are able to improve their engineering mindset and innovation consciousness.

Fluorene-based macromolecular nanostructures and nanomaterials for organic (opto)electronics.

Science.gov (United States)

Xie, Ling-Hai; Yang, Su-Hui; Lin, Jin-Yi; Yi, Ming-Dong; Huang, Wei

2013-10-13

Nanotechnology not only opens up the realm of nanoelectronics and nanophotonics, but also upgrades organic thin-film electronics and optoelectronics. In this review, we introduce polymer semiconductors and plastic electronics briefly, followed by various top-down and bottom-up nano approaches to organic electronics. Subsequently, we highlight the progress in polyfluorene-based nanoparticles and nanowires (nanofibres), their tunable optoelectronic properties as well as their applications in polymer light-emitting devices, solar cells, field-effect transistors, photodetectors, lasers, optical waveguides and others. Finally, an outlook is given with regard to four-element complex devices via organic nanotechnology and molecular manufacturing that will spread to areas such as organic mechatronics in the framework of robotic-directed science and technology.

Optimizing the Recognition of Surface Crystallography

Czech Academy of Sciences Publication Activity Database

Frank, Luděk; Mika, Filip; Müllerová, Ilona

2015-01-01

Roč. 21, S4 (2015), s. 124-129 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : surface crystallography Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

Comparison of waxy and normal potato starch remaining granules after chemical surface gelatinization: Pasting behavior and surface morphology

NARCIS (Netherlands)

Huang, J.; Chen Zenghong,; Xu, Yalun; Li, Hongliang; Liu, Shuxing; Yang, Daqing; Schols, H.A.

2014-01-01

o understand the contribution of granule inner portion to the pasting property of starch, waxy potato starch and two normal potato starches and their acetylated starch samples were subjected to chemical surface gelatinization by 3.8 mol/L CaCl2 to obtain remaining granules. Native and acetylated,

Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

KAUST Repository

Botiz, Ioan; Stingelin, Natalie

2014-01-01

It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties. © 2014 by the authors.

Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

Directory of Open Access Journals (Sweden)

Ioan Botiz

2014-03-01

Full Text Available It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties.

Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

KAUST Repository

Botiz, Ioan

2014-03-19

It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties. © 2014 by the authors.

Optoelectronic properties of doped hydrothermal ZnO thin films

KAUST Repository

Mughal, Asad J.; Carberry, Benjamin; Oh, Sang Ho; Myzaferi, Anisa; Speck, James S.; Nakamura, Shuji; DenBaars, Steven P.

2017-01-01

, or In were evaluated for their optoelectronic properties. Inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of dopants within the ZnO films. While Al and Ga-doped films showed linear incorporation rates

Advances in wide bandgap SiC for optoelectronics

DEFF Research Database (Denmark)

Ou, Haiyan; Ou, Yiyu; Argyraki, Aikaterini

2014-01-01

Silicon carbide (SiC) has played a key role in power electronics thanks to its unique physical properties like wide bandgap, high breakdown field, etc. During the past decade, SiC is also becoming more and more active in optoelectronics thanks to the progress in materials growth and nanofabrication...

Graduate studies on optoelectronics in Argentina: an experience

Science.gov (United States)

Fernández, Juan C.; Garea, María. T.; Isaurralde, Silvia; Perez, Liliana I.; Raffo, Carlos A.

2014-07-01

The number of graduate programs in Optoelectronics in Argentina is scarce. The current Optics and Photonics Education Directory lists only three programs. One of them was launched in 2001 in the Facultad de Ingeniería (College of Engineering), Universidad de Buenos Aires (UBA). This was the first graduate program in the field, leading to a Master Degree in Optoelectronics. This decision arose from the demand of telecommunications industries and several estate- or private-funded research institutions working with us in the fields of lasers, optics, remote sensing, etc. A great bonus was the steady work, during several decades, of research groups in the College on the development of different type of lasers and optical non destructive tests and their engineering applications. As happened in many engineering graduate programs in Argentina at that time, few non full-time students could finish their studies, which called for 800 hours of traditional lecture-recitation classes, and the Master Thesis. In recent years Argentine Education authorities downsized the Master programs to 700 hours of blended learning and we redesigned the Graduate Optoelectronic Engineering Program to meet the challenge, dividing it in two successive one year programs, the first aimed at a professional training for almost immediate insertion in the labor market (called Especialización en Ingeniería Optoelectrónica), and the second (called Maestría en Ingeniería Optoelectrónica y Fotónica) aimed at a more academic and research target to comply with the UBA standards for Master degrees. The present work is a presentation of the new program design, which has begun in the current year.

Metal Complexes for Organic Optoelectronic Applications

Science.gov (United States)

Huang, Liang

Organic optoelectronic devices have drawn extensive attention by over the past two decades. Two major applications for Organic optoelectronic devices are efficient organic photovoltaic devices(OPV) and organic light emitting diodes (OLED). Organic Solar cell has been proven to be compatible with the low cost, large area bulk processing technology and processed high absorption efficiencies compared to inorganic solar cells. Organic light emitting diodes are a promising approach for display and solid state lighting applications. To improve the efficiency, stability, and materials variety for organic optoelectronic devices, several emissive materials, absorber-type materials, and charge transporting materials were developed and employed in various device settings. Optical, electrical, and photophysical studies of the organic materials and their corresponding devices were thoroughly carried out. In this thesis, Chapter 1 provides an introduction to the background knowledge of OPV and OLED research fields presented. Chapter 2 discusses new porphyrin derivatives- azatetrabenzylporphyrins for OPV and near infrared OLED applications. A modified synthetic method is utilized to increase the reaction yield of the azatetrabenzylporphyrin materials and their photophysical properties, electrochemical properties are studied. OPV devices are also fabricated using Zinc azatetrabenzylporphyrin as donor materials. Pt(II) azatetrabenzylporphyrin were also synthesized and used in near infra-red OLED to achieve an emission over 800 nm with reasonable external quantum efficiencies. Chapter 3, discusses the synthesis, characterization, and device evaluation of a series of tetradentate platinum and palladium complexesfor single doped white OLED applications and RGB white OLED applications. Devices employing some of the developed emitters demonstrated impressively high external quantum efficiencies within the range of 22%-27% for various emitter concentrations. And the palladium complex, i

Opto-electronic devices from block copolymers and their oligomers.

NARCIS (Netherlands)

Hadziioannou, G

1997-01-01

This paper presents research activities towards the development of polymer materials and devices for optoelectronics, An approach to controlling the conjugation length and transferring the luminescence properties of organic molecules to polymers through black copolymers containing well-defined

Studies on the optoelectronic properties of the thermally evaporated tin-doped indium oxide nanostructures

Energy Technology Data Exchange (ETDEWEB)

Pan, Ko-Ying [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan, ROC (China); Lin, Liang-Da [Institute of Materials Science and Nanotechnology, Chinese Culture University, Taipei 111, Taiwan, ROC (China); Chang, Li-Wei [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan, ROC (China); Shih, Han C., E-mail: hcshih@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan, ROC (China); Institute of Materials Science and Nanotechnology, Chinese Culture University, Taipei 111, Taiwan, ROC (China)

2013-05-15

Indium oxide (In{sub 2}O{sub 3}) nanorods, nanotowers and tin-doped (Sn:In = 1:100) indium oxide (ITO) nanorods have been fabricated by thermal evaporation. The morphology, microstructure and chemical composition of these three nanoproducts are characterized by FE-SEM, HRTEM and XPS. To further investigate the optoelectronic properties, the I–V curves and cathodoluminescence (CL) spectra are measured. The electrical resistivity of In{sub 2}O{sub 3} nanorods, nanotowers and ITO nanorods are 1.32 kΩ, 0.65 kΩ and 0.063 kΩ, respectively. CL spectra of these three nanoproducts clearly indicate that tin-doped (Sn:In = 1:100) indium oxide (ITO) nanorods cause a blue shift. No doubt ITO nanorods obtain the highest performance among these three nanoproducts, and this also means that Sn-doped In{sub 2}O{sub 3} nanostructures would be the best way to enhance the optoelectronic properties. Additionally, the growing mechanism and the optoelectronic properties of these three nanostructures are discussed. This study is beneficial to the applications of In{sub 2}O{sub 3} nanorods, nanotowers and ITO nanorods in optoelectronic nanodevices.

Optoelectronic inventory system for special nuclear material

International Nuclear Information System (INIS)

Sieradzki, F.H.

1994-01-01

In support of the Department of Energy's Dismantlement Program, the Optoelectronics Characterization and Sensor Development Department 2231 at Sandia National Laboratories/New Mexico has developed an in situ nonintrusive Optoelectronic Inventory System (OIS) that has the potential for application wherever periodic inventory of selected material is desired. Using a network of fiber-optic links, the OIS retrieves and stores inventory signatures from data storage devices (which are permanently attached to material storage containers) while inherently providing electromagnetic pulse immunity and electrical noise isolation. Photovoltaic cells (located within the storage facility) convert laser diode optic power from a laser driver to electrical energy. When powered and triggered, the data storage devices sequentially output their digital inventory signatures through light-emitting diode/photo diode data links for retrieval and storage in a mobile data acquisition system. An item's exact location is determined through fiber-optic network and software design. The OIS provides an on-demand method for obtaining acceptable inventory reports while eliminating the need for human presence inside the material storage facility. By using modularization and prefabricated construction with mature technologies and components, an OIS installation with virtually unlimited capacity can be tailored to the customer's requirements

Internal structure of normal maize starch granules revealed by chemical surface gelatinization.

Science.gov (United States)

Pan, D D; Jane, J I

2000-01-01

Normal maize starch was fractionated into two sizes: large granules with diameters more than 5 microns and small granules with diameters less than 5 microns. The large granules were surface gelatinized by treating them with an aqueous LiCl solution (13 M) at 22-23 degrees C. Surface-gelatinized remaining granules were obtained by mechanical blending, and gelatinized surface starch was obtained by grinding with a mortar and a pestle. Starches of different granular sizes and radial locations, obtained after different degrees of surface gelatinization, were subjected to scanning electron microscopy, iodine potentiometric titration, gel-permeation chromatography, and amylopectin branch chain length analysis. Results showed that the remaining granules had a rough surface with a lamella structure. Amylose was more concentrated at the periphery than at the core of the granule. Amylopectin had longer long B-chains at the core than at the periphery of the granule. Greater proportions of the long B-chains were present at the core than at the periphery of the granule.

Two-Dimensional CH₃NH₃PbI₃ Perovskite: Synthesis and Optoelectronic Application.

Science.gov (United States)

Liu, Jingying; Xue, Yunzhou; Wang, Ziyu; Xu, Zai-Quan; Zheng, Changxi; Weber, Bent; Song, Jingchao; Wang, Yusheng; Lu, Yuerui; Zhang, Yupeng; Bao, Qiaoliang

2016-03-22

Hybrid organic-inorganic perovskite materials have received substantial research attention due to their impressively high performance in photovoltaic devices. As one of the oldest functional materials, it is intriguing to explore the optoelectronic properties in perovskite after reducing it into a few atomic layers in which two-dimensional (2D) confinement may get involved. In this work, we report a combined solution process and vapor-phase conversion method to synthesize 2D hybrid organic-inorganic perovskite (i.e., CH3NH3PbI3) nanocrystals as thin as a single unit cell (∼1.3 nm). High-quality 2D perovskite crystals have triangle and hexagonal shapes, exhibiting tunable photoluminescence while the thickness or composition is changed. Due to the high quantum efficiency and excellent photoelectric properties in 2D perovskites, a high-performance photodetector was demonstrated, in which the current can be enhanced significantly by shining 405 and 532 nm lasers, showing photoresponsivities of 22 and 12 AW(-1) with a voltage bias of 1 V, respectively. The excellent optoelectronic properties make 2D perovskites building blocks to construct 2D heterostructures for wider optoelectronic applications.

Continuum modeling of ion-beam eroded surfaces under normal incidence: Impact of stochastic fluctuations

International Nuclear Information System (INIS)

Dreimann, Karsten; Linz, Stefan J.

2010-01-01

Graphical abstract: Deterministic surface pattern (left) and its stochastic counterpart (right) arising in a stochastic damped Kuramoto-Sivashinsky equation that serves as a model equation for ion-beam eroded surfaces and is systematically investigated. - Abstract: Using a recently proposed field equation for the surface evolution of ion-beam eroded semiconductor target materials under normal incidence, we systematically explore the impact of additive stochastic fluctuations that are permanently present during the erosion process. Specifically, we investigate the dependence of the surface roughness, the underlying pattern forming properties and the bifurcation behavior on the strength of the fluctuations.

Optoelectronic pH Meter: Further Details

Science.gov (United States)

Jeevarajan, Antony S.; Anderson, Mejody M.; Macatangay, Ariel V.

2009-01-01

A collection of documents provides further detailed information about an optoelectronic instrument that measures the pH of an aqueous cell-culture medium to within 0.1 unit in the range from 6.5 to 7.5. The instrument at an earlier stage of development was reported in Optoelectronic Instrument Monitors pH in a Culture Medium (MSC-23107), NASA Tech Briefs, Vol. 28, No. 9 (September 2004), page 4a. To recapitulate: The instrument includes a quartz cuvette through which the medium flows as it is circulated through a bioreactor. The medium contains some phenol red, which is an organic pH-indicator dye. The cuvette sits between a light source and a photodetector. [The light source in the earlier version comprised red (625 nm) and green (558 nm) light-emitting diodes (LEDs); the light source in the present version comprises a single green- (560 nm)-or-red (623 nm) LED.] The red and green are repeatedly flashed in alternation. The responses of the photodiode to the green and red are processed electronically to obtain the ratio between the amounts of green and red light transmitted through the medium. The optical absorbance of the phenol red in the green light varies as a known function of pH. Hence, the pH of the medium can be calculated from the aforesaid ratio.

Asymmetric transmission of surface plasmon polaritons

Czech Academy of Sciences Publication Activity Database

Kuzmiak, Vladimír; Maradudin, A.

2012-01-01

Roč. 86, č. 4 (2012), s. 043805 ISSN 1050-2947 R&D Projects: GA MŠk LH12009 Institutional support: RVO:67985882 Keywords : one-way duffarction grating * scattering * surface plasmon polarirton Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.042, year: 2012

Simultaneous topographical, electrical and optical microscopy of optoelectronic devices at the nanoscale

KAUST Repository

Kumar, Naresh

2017-01-12

Novel optoelectronic devices rely on complex nanomaterial systems where the nanoscale morphology and local chemical composition are critical to performance. However, the lack of analytical techniques that can directly probe these structure-property relationships at the nanoscale presents a major obstacle to device development. In this work, we present a novel method for non-destructive, simultaneous mapping of the morphology, chemical composition and photoelectrical properties with <20 nm spatial resolution by combining plasmonic optical signal enhancement with electrical-mode scanning probe microscopy. We demonstrate that this combined approach offers subsurface sensitivity that can be exploited to provide molecular information with a nanoscale resolution in all three spatial dimensions. By applying the technique to an organic solar cell device, we show that the inferred surface and subsurface composition distribution correlates strongly with the local photocurrent generation and explains macroscopic device performance. For instance, the direct measurement of fullerene phase purity can distinguish between high purity aggregates that lead to poor performance and lower purity aggregates (fullerene intercalated with polymer) that result in strong photocurrent generation and collection. We show that the reliable determination of the structure-property relationship at the nanoscale can remove ambiguity from macroscopic device data and support the identification of the best routes for device optimisation. The multi-parameter measurement approach demonstrated herein is expected to play a significant role in guiding the rational design of nanomaterial-based optoelectronic devices, by opening a new realm of possibilities for advanced investigation via the combination of nanoscale optical spectroscopy with a whole range of scanning probe microscopy modes.

GaN nano-membrane for optoelectronic and electronic device applications

KAUST Repository

Ooi, Boon S.

2014-01-01

The ~25nm thick threading dislocation free GaN nanomembrane was prepared using ultraviolet electroless chemical etching method offering the possibility of flexible integration of (Al,In,Ga)N optoelectronic and electronic devices.

Light box for investigation of characteristics of optoelectronics detectors

Science.gov (United States)

Szreder, Agnieszka; Mazikowski, Adam

2017-09-01

In this paper, a light box for investigation of characteristics of optoelectronic detectors is described. The light box consists of an illumination device, an optical power sensor and a mechanical enclosure. The illumination device is based on four types of high-power light emitting diodes (LED): white light, red, green and blue. The illumination level can be varied for each LED independently by the driver and is measured by optical power sensor. The mechanical enclosure provides stable mounting points for the illumination device, sensor and the examined detector and protects the system from external light, which would otherwise strongly influence the measurement results. Uniformity of illumination distribution provided by the light box for all colors is good, making the measurement results less dependent on the position of the examined detector. The response of optoelectronic detectors can be investigated using the developed light box for each LED separately or for any combination of up to four LED types. As the red, green and blue LEDs are rather narrow bandwidth sources, spectral response of different detectors can be examined for these wavelength ranges. The described light box can be used for different applications. Its primary use is in a student laboratory setup for investigation of characteristics of optoelectronic detectors. Moreover, it can also be used in various colorimetric or photographic applications. Finally, it will be used as a part of demonstrations from the fields of vision and color, performed during science fairs and outreach activities increasing awareness of optics and photonics.

Controlling the surface photovoltage on WSe2 by surface chemical modification

Science.gov (United States)

Liu, Ro-Ya; Ozawa, Kenichi; Terashima, Naoya; Natsui, Yuto; Feng, Baojie; Ito, Suguru; Chen, Wei-Chuan; Cheng, Cheng-Maw; Yamamoto, Susumu; Kato, Hiroo; Chiang, Tai-Chang; Matsuda, Iwao

2018-05-01

The surface photovoltage (SPV) effect is key to the development of opto-electronic devices such as solar-cells and photo-detectors. For the prototypical transition metal dichalcogenide WSe2, core level and valence band photoemission measurements show that the surface band bending of pristine cleaved surfaces can be readily modified by adsorption with K (an electron donor) or C60 (an electron acceptor). Time-resolved pump-probe photoemission measurements reveal that the SPV for pristine cleaved surfaces is enhanced by K adsorption, but suppressed by C60 adsorption, and yet the SPV relaxation time is substantially shortened in both cases. Evidently, adsorbate-induced electronic states act as electron-hole recombination centers that shorten the carrier lifetime.

Divergent synthesis and optoelectronic properties of oligodiacetylene building blocks

NARCIS (Netherlands)

Pilzak, G.S.; Lagen, van B.; Sudhölter, E.J.R.; Zuilhof, H.

2008-01-01

A new and divergent synthetic route to oligodiacetylene (ODA) building blocks has been developed via Sonogashira reactions under a reductive atmosphere. These central building blocks provide a new way for rapid preparation of long ODAs. In addition, we report on their optoelectronic properties which

High-resolution biosensor based on localized surface plasmons

Czech Academy of Sciences Publication Activity Database

Piliarik, Marek; Šípová, Hana; Kvasnička, Pavel; Galler, N.; Krenn, J. R.; Homola, Jiří

2012-01-01

Roč. 20, č. 1 (2012), s. 672-680 ISSN 1094-4087 R&D Projects: GA AV ČR KAN200670701; GA MŠk OC09058 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical biosenzor * surface plasmon resonance * localized surface plasmon Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.546, year: 2012

Growth of contact area between rough surfaces under normal stress

Science.gov (United States)

Stesky, R. M.; Hannan, S. S.

1987-05-01

The contact area between deforming rough surfaces in marble, alabaster, and quartz was measured from thin sections of surfaces bonded under load with low viscosity resin epoxy. The marble and alabaster samples had contact areas that increased with stress at an accelerating rate. This result suggests that the strength of the asperity contacts decreased progressively during the deformation, following some form of strain weakening relationship. This conclusion is supported by petrographic observation of the thin sections that indicate that much of the deformation was cataclastic, with minor twinning of calcite and kinking of gypsum. In the case of the quartz, the observed contact area was small and increased approximately linearly with normal stress. Only the irreversible cataclastic deformation was observed; however strain-induced birefringence and cracking of the epoxy, not observed with the other rocks, suggests that significant elastic deformation occurred, but recovered during unloading.

Stability analysis of rough surfaces in adhesive normal contact

Science.gov (United States)

Rey, Valentine; Bleyer, Jeremy

2018-03-01

This paper deals with adhesive frictionless normal contact between one elastic flat solid and one stiff solid with rough surface. After computation of the equilibrium solution of the energy minimization principle and respecting the contact constraints, we aim at studying the stability of this equilibrium solution. This study of stability implies solving an eigenvalue problem with inequality constraints. To achieve this goal, we propose a proximal algorithm which enables qualifying the solution as stable or unstable and that gives the instability modes. This method has a low computational cost since no linear system inversion is required and is also suitable for parallel implementation. Illustrations are given for the Hertzian contact and for rough contact.

Dental impression technique using optoelectronic devices

Science.gov (United States)

Sinescu, Cosmin; Barua, Souman; Topala, Florin Ionel; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Gabor, Alin Gabriel; Zaharia, Cristian; Bradu, Adrian; Podoleanu, Adrian G.

2018-03-01

INTRODUCTION: The use of Optical Coherence Tomography (OCT) as a non-invasive and high precision quantitative information providing tool has been well established by researches within the last decade. The marginal discrepancy values can be scrutinized in optical biopsy made in three dimensional (3D) micro millimetre scale and reveal detailed qualitative and quantitative information of soft and hard tissues. OCT-based high resolution 3D images can provide a significant impact on finding recurrent caries, restorative failure, analysing the precision of crown preparation, and prosthetic elements marginal adaptation error with the gingiva and dental hard tissues. During the CAD/CAM process of prosthodontic restorations, the circumvent of any error is important for the practitioner and the technician to reduce waste of time and material. Additionally, OCT images help to achieve a new or semi-skilled practitioner to analyse their crown preparation works and help to develop their skills faster than in a conventional way. The aim of this study is to highlight the advantages of OCT in high precision prosthodontic restorations. MATERIALS AND METHODS: 25 preparations of frontal and lateral teeth were performed for 7 different patients. The impressions of the prosthetic fields were obtained both using a conventional optoelectronic system (Apolo Di, Syrona) and a Spectral Domain using OCT (Dental prototype, working at 860 nm). For the conventional impression technique the preparation margins were been prelevated by gingival impregnated cords. No specific treatments were performed by the OCT impression technique. RESULTS: The scanning performed by conventional optoelectronic system proved to be quick and accurate in terms of impression technology. The results were represented by 3D virtual models obtained after the scanning procedure was completed. In order to obtain a good optical impression a gingival retraction cord was inserted between the prepared tooth and the gingival

Growing perovskite into polymers for easy-processable optoelectronic devices

Science.gov (United States)

Masi, Sofia; Colella, Silvia; Listorti, Andrea; Roiati, Vittoria; Liscio, Andrea; Palermo, Vincenzo; Rizzo, Aurora; Gigli, Giuseppe

2015-01-01

Here we conceive an innovative nanocomposite to endow hybrid perovskites with the easy processability of polymers, providing a tool to control film quality and material crystallinity. We verify that the employed semiconducting polymer, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), controls the self-assembly of CH3NH3PbI3 (MAPbI3) crystalline domains and favors the deposition of a very smooth and homogenous layer in one straightforward step. This idea offers a new paradigm for the implementation of polymer/perovskite nanocomposites towards versatile optoelectronic devices combined with the feasibility of mass production. As a proof-of-concept we propose the application of such nanocomposite in polymer solar cell architecture, demonstrating a power conversion efficiency up to 3%, to date the highest reported for MEH-PPV. On-purpose designed polymers are expected to suit the nanocomposite properties for the integration in diverse optoelectronic devices via facile processing condition.

Piezophototronic Effect in Single-Atomic-Layer MoS ₂ for Strain-Gated Flexible Optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Wu, Wenzhuo [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta GA 30332-0245 USA; Wang, Lei [Department of Electrical Engineering, Columbia University, New York NY 10027 USA; Yu, Ruomeng [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta GA 30332-0245 USA; Liu, Yuanyue [National Renewable Energy Laboratory (NREL), Golden CO 80401 USA; Wei, Su-Huai [National Renewable Energy Laboratory (NREL), Golden CO 80401 USA; Hone, James [Department of Mechanical Engineering, Columbia University, New York NY 10027 USA; Wang, Zhong Lin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta GA 30332-0245 USA; Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, 100083 Beijing China

2016-08-03

Strain-gated flexible optoelectronics are reported based on monolayer MoS2. Utilizing the piezoelectric polarization created at metal-MoS2 interface to modulate the separation/transport of photogenerated carriers, the piezophototronic effect is applied to implement atomic-layer-thick phototransistor. Coupling between piezoelectricity and photogenerated carriers may enable the development of novel optoelectronics.

Design of optoelectronic system to meter of electrical current to the habitation house

International Nuclear Information System (INIS)

Camas, J.; Flores, M.; Anzuelo, G.; Garcia, C.; Juarez, N.; Torres, W.; Mota, R.

2009-01-01

In this work, we present an optoelectronic digital meter of electrical current. The development of this design is described step by step with diagram to blocks. The advantage over conventional meters of CFE (Comision Federal de electricidad) and the design proposed are analyzed. Information in the optoelectronic design is controlled by Microcontroller PIC16F877. This Microcontroller uses an external crystal as an oscillator with a 4 MHz frequency. The information is shown in a LCD (Liquid Crystal Display). In addition, to quantify the electrical current was necessary an interruption of light. (Author)

Flexible and Stretchable Optoelectronic Devices using Silver Nanowires and Graphene.

Science.gov (United States)

Lee, Hanleem; Kim, Meeree; Kim, Ikjoon; Lee, Hyoyoung

2016-06-01

Many studies have accompanied the emergence of a great interest in flexible or/and stretchable devices for new applications in wearable and futuristic technology, including human-interface devices, robotic skin, and biometric devices, and in optoelectronic devices. Especially, new nanodimensional materials enable flexibility or stretchability to be brought based on their dimensionality. Here, the emerging field of flexible devices is briefly introduced using silver nanowires and graphene, which are famous nanomaterials for the use of transparent conductive electrodes, as examples, and their unique functions originating from the intrinsic property of these nanomaterials are highlighted. It is thought that this work will evoke more interest and idea exchanges in this emerging field and hopefully can trigger a breakthrough on a new type of optoelectronics and optogenetic devices in the near future. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Compensating Unknown Time-Varying Delay in Opto-Electronic Platform Tracking Servo System

Directory of Open Access Journals (Sweden)

Ruihong Xie

2017-05-01

Full Text Available This paper investigates the problem of compensating miss-distance delay in opto-electronic platform tracking servo system. According to the characteristic of LOS (light-of-sight motion, we setup the Markovian process model and compensate this unknown time-varying delay by feed-forward forecasting controller based on robust H∞ control. Finally, simulation based on double closed-loop PI (Proportion Integration control system indicates that the proposed method is effective for compensating unknown time-varying delay. Tracking experiments on the opto-electronic platform indicate that RMS (root-mean-square error is 1.253 mrad when tracking 10° 0.2 Hz signal.

Optoelectronic fowl adenovirus detection based on local electric field enhancement on graphene quantum dots and gold nanobundle hybrid.

Science.gov (United States)

Ahmed, Syed Rahin; Mogus, Jack; Chand, Rohit; Nagy, Eva; Neethirajan, Suresh

2018-04-30

An optoelectronic sensor is a rapid diagnostic tool that allows for an accurate, reliable, field-portable, low-cost device for practical applications. In this study, template-free In situ gold nanobundles (Au NBs) were fabricated on an electrode for optoelectronic sensing of fowl adenoviruses (FAdVs). Au NB film was fabricated on carbon electrodes working area using L(+) ascorbic acid, gold chroloauric acid and poly-l-lysine (PLL) through modified layer-by-layer (LbL) method. A scanning electron microscopic (SEM) image of the Au NBs revealed a NB-shaped Au structure with many kinks on its surface, which allow local electric field enhancement through light-matter interaction with graphene quantum dots (GQDs). Here, GQDs were synthesized through an autoclave-assisted method. Characterization experiments revealed blue-emissive, well-dispersed GQDs that were 2-3nm in size with the fluorescence emission peak of GQDs located at 405nm. Both Au NBs and GQDs were conjugated with target FAdVs specific antibodies that bring them close to each other with the addition of target FAdVs through antibody-antigen interaction. At close proximity, light-matter interaction between Au NBs and QDs produces a local electric signal enhancement under Ultraviolet-visible (UV-visible) light irradiation that allows the detection of very low concentrations of target virus even in complex biological media. A proposed optoelectronic sensor showed a linear relationship between the target FAdVs and the electric signal up to 10 Plaque forming unit (PFU)/mL with a limit of detection (LOD) of 8.75 PFU/mL. The proposed sensing strategy was 100 times more sensitive than conventional ELISA method. Copyright © 2017 Elsevier B.V. All rights reserved.

New pathways in electronics and optoelectronics driven by new physics of nonconventional materials

International Nuclear Information System (INIS)

Kantser, Valeriu

2015-01-01

Nonconventional materials (NCM) - 2D materials and topological insulators (TI) - have opened a gateway to search new physical phenomena and states of the condensed matter as well as to pave new platform of modern technology. This stems on their unique attributes - non equivalence of electronic and dielectric states to vacuum ones, topological protection (reduced backscattering), spin momentum locking property, magnetoelectric coupling, generations of new quasiparticles like Majorana fermions. Increasing the surface state contribution in proportion to the bulk is critical to investigate the surface states and for future innovative device applications. The way to achieve this is to configure NCM into nanostructures, which at the same time in combination with others materials significantly enlarge the variety of new states and phenomena. This article reviews the recent progress made in NCM and nano heterostructures investigation. The state of art of different new scenario of engineering topologically interface states in the TI heterostructures are revealed, in particular by using polarization fields and antiferromagnetic ordering. Some of new proposals for innovative electronic and optoelectronic devices are discussed. (author)

Technical quality assessment of an optoelectronic system for movement analysis

International Nuclear Information System (INIS)

Sapienza University of Rome (Italy))" data-affiliation=" (Department of Mechanical and Aerospace Engineering, Sapienza University of Rome (Italy))" >Di Marco, R; Sapienza University of Rome (Italy))" data-affiliation=" (Department of Mechanical and Aerospace Engineering, Sapienza University of Rome (Italy))" >Patanè, F; Sapienza University of Rome (Italy))" data-affiliation=" (Department of Mechanical and Aerospace Engineering, Sapienza University of Rome (Italy))" >Cappa, P; Rossi, S

2015-01-01

The Optoelectronic Systems (OS) are largely used in gait analysis to evaluate the motor performances of healthy subjects and patients. The accuracy of marker trajectories reconstruction depends on several aspects: the number of cameras, the dimension and position of the calibration volume, and the chosen calibration procedure. In this paper we propose a methodology to evaluate the effects of the mentioned sources of error on the reconstruction of marker trajectories. The novel contribution of the present work consists in the dimension of the tested calibration volumes, which is comparable with the ones normally used in gait analysis; in addition, to simulate trajectories during clinical gait analysis, we provide non-default paths for markers as inputs. Several calibration procedures are implemented and the same trial is processed with each calibration file, also considering different cameras configurations. The RMSEs between the measured trajectories and the optimal ones are calculated for each comparison. To investigate the significant differences between the computed indices, an ANOVA analysis is implemented. The RMSE is sensible to the variations of the considered calibration volume and the camera configurations and it is always inferior to 43 mm

Tailoring uniform gold nanoparticle arrays and nanoporous films for next-generation optoelectronic devices

Science.gov (United States)

Farid, Sidra; Kuljic, Rade; Poduri, Shripriya; Dutta, Mitra; Darling, Seth B.

2018-06-01

High-density arrays of gold nanodots and nanoholes on indium tin oxide (ITO)-coated glass surfaces are fabricated using a nanoporous template fabricated by the self-assembly of diblock copolymers of poly (styrene-block-methyl methacrylate) (PS-b-PMMA) structures. By balancing the interfacial interactions between the polymer blocks and the substrate using random copolymer, cylindrical block copolymer microdomains oriented perpendicular to the plane of the substrate have been obtained. Nanoporous PS films are created by selectively etching PMMA cylinders, a straightforward route to form highly ordered nanoscale porous films. Deposition of gold on the template followed by lift off and sonication leaves a highly dense array of gold nanodots. These materials can serve as templates for the vapor-liquid-solid (VLS) growth of semiconductor nanorod arrays for next generation hybrid optoelectronic applications.

Estimation of Dynamic Errors in Laser Optoelectronic Dimension Gauges for Geometric Measurement of Details

Directory of Open Access Journals (Sweden)

Khasanov Zimfir

2018-01-01

Full Text Available The article reviews the capabilities and particularities of the approach to the improvement of metrological characteristics of fiber-optic pressure sensors (FOPS based on estimation estimation of dynamic errors in laser optoelectronic dimension gauges for geometric measurement of details. It is shown that the proposed criteria render new methods for conjugation of optoelectronic converters in the dimension gauge for geometric measurements in order to reduce the speed and volume requirements for the Random Access Memory (RAM of the video controller which process the signal. It is found that the lower relative error, the higher the interrogetion speed of the CCD array. It is shown that thus, the maximum achievable dynamic accuracy characteristics of the optoelectronic gauge are determined by the following conditions: the parameter stability of the electronic circuits in the CCD array and the microprocessor calculator; linearity of characteristics; error dynamics and noise in all electronic circuits of the CCD array and microprocessor calculator.

Spectroscopic investigation of the chemical and electronic properties of chalcogenide materials for thin-film optoelectronic devices

Science.gov (United States)

Horsley, Kimberly Anne

Chalcogen-based materials are at the forefront of technologies for sustainable energy production. This progress has come only from decades of research, and further investigation is needed to continue improvement of these materials. For this dissertation, a number of chalcogenide systems were studied, which have applications in optoelectronic devices, such as LEDs and Photovoltaics. The systems studied include Cu(In,Ga)Se2 (CIGSe) and CuInSe 2 (CISe) thin-film absorbers, CdTe-based photovoltaic structures, and CdTe-ZnO nanocomposite materials. For each project, a sample set was prepared through collaboration with outside institutions, and a suite of spectroscopy techniques was employed to answer specific questions about the system. These techniques enabled the investigation of the chemical and electronic structure of the materials, both at the surface and towards the bulk. CdS/Cu(In,Ga)Se2 thin-films produced from the roll-to-roll, ambient pressure, Nanosolar industrial line were studied. While record-breaking efficiency cells are usually prepared in high-vacuum (HV) or ultra-high vacuum (UHV) environments, these samples demonstrate competitive mass-production efficiency without the high-cost deposition environment. We found relatively low levels of C contaminants, limited Na and Se oxidation, and a S-Se intermixing at the CdS/CIGSe interface. The surface band gap compared closely to previously investigated CIGSe thin-films deposited under vacuum, illustrating that roll-to-roll processing is a promising and less-expensive alternative for solar cell production. An alternative deposition process for CuInSe2 was also studied, in collaboration with the University of Luxembourg. CuInSe2 absorbers were prepared with varying Cu content and surface treatments to investigate the potential to produce an absorber with a Cu-rich bulk and Cu-poor surface. This is desired to combine the bulk characteristics of reduced defects and larger grains in Cu-rich films, while maintaining

Photon management of GaN-based optoelectronic devices via nanoscaled phenomena

KAUST Repository

Tsai, Yu-Lin; Lai, Kun-Yu; Lee, Ming-Jui; Liao, Yu-Kuang; Ooi, Boon S.; Kuo, Hao-Chung; He, Jr-Hau

2016-01-01

Photon management is essential in improving the performances of optoelectronic devices including light emitting diodes, solar cells and photo detectors. Beyond the advances in material growth and device structure design, photon management via

Improving the security of optoelectronic delayed feedback system by parameter modulation and system coupling

Science.gov (United States)

Liu, Lingfeng; Miao, Suoxia; Cheng, Mengfan; Gao, Xiaojing

2016-02-01

A coupled system with varying parameters is proposed to improve the security of optoelectronic delayed feedback system. This system is coupled by two parameter-varied optoelectronic delayed feedback systems with chaotic modulation. Dynamics performance results show that this system has a higher complexity compared to the original one. Furthermore, this system can conceal the time delay effectively against the autocorrelation function and delayed mutual information method and can increase the dimension space of secure parameters to resist brute-force attack by introducing the digital chaotic systems.

Optoelectronic sensor device for monitoring ethanol concentration in winemaking applications

Science.gov (United States)

Jiménez-Márquez, F.; Vázquez, J.; Úbeda, J.; Rodríguez-Rey, J.; Sánchez-Rojas, J. L.

2015-05-01

The supervision of key variables such as sugar, alcohol, released CO2 and microbiological evolution in fermenting grape must is of great importance in the winemaking industry. However, the fermentation kinetics is assessed by monitoring the evolution of the density as it varies during a fermentation, since density is an indicator of the total amount of sugars, ethanol and glycerol. Even so, supervising the fermentation process is an awkward and non-comprehensive task, especially in wine cellars where production rates are massive, and enologists usually measure the density of the extracted samples from each fermentation tank manually twice a day. This work aims at the design of a fast, low-cost, portable and reliable optoelectronic sensor for measuring ethanol concentration in fermenting grape must samples. Different sets of model solutions, which contain ethanol, fructose, glucose, glycerol dissolved in water and emulate the grape must composition at different stages of the fermentation, were prepared both for calibration and validation. The absorption characteristics of these model solutions were analyzed by a commercial spectrophotometer in the NIR region, in order to identify key wavelengths from which valuable information regarding the sample composition can be extracted. Finally, a customized optoelectronic prototype based on absorbance measurements at two wavelengths belonging to the NIR region was designed, fabricated and successfully tested. The system, whose optoelectronics is reduced after a thorough analysis to only two LED lamps and their corresponding paired photodiodes operating at 1.2 and 1.3 μm respectively, calculates the ethanol content by a multiple linear regression.

Optoelectronic holographic otoscope for measurement of nano-displacements in tympanic membranes

Science.gov (United States)

Del Socorro Hernández-Montes, Maria; Furlong, Cosme; Rosowski, John J.; Hulli, Nesim; Harrington, Ellery; Cheng, Jeffrey Tao; Ravicz, Michael E.; Santoyo, Fernando Mendoza

2009-05-01

Current methodologies for characterizing tympanic membrane (TM) motion are usually limited to either average acoustic estimates (admittance or reflectance) or single-point mobility measurements, neither of which suffices to characterize the detailed mechanical response of the TM to sound. Furthermore, while acoustic and single-point measurements may aid in diagnosing some middle-ear disorders, they are not always useful. Measurements of the motion of the entire TM surface can provide more information than these other techniques and may be superior for diagnosing pathology. We present advances in our development of a new compact optoelectronic holographic otoscope (OEHO) system for full field-of-view characterization of nanometer-scale sound-induced displacements of the TM surface at video rates. The OEHO system consists of a fiber optic subsystem, a compact otoscope head, and a high-speed image processing computer with advanced software for recording and processing holographic images coupled to a computer-controlled sound-stimulation and recording system. A prototype OEHO system is in use in a medical research environment to address basic science questions regarding TM function. The prototype provides real-time observation of sound-induced TM displacement patterns over a broad frequency range. Representative time-averaged and stroboscopic holographic interferometry results in animals and human cadaver samples are shown, and their potential utility is discussed.

Development of an optoelectronic holographic platform for otolaryngology applications

Science.gov (United States)

Harrington, Ellery; Dobrev, Ivo; Bapat, Nikhil; Flores, Jorge Mauricio; Furlong, Cosme; Rosowski, John; Cheng, Jeffery Tao; Scarpino, Chris; Ravicz, Michael

2010-08-01

In this paper, we present advances on our development of an optoelectronic holographic computing platform with the ability to quantitatively measure full-field-of-view nanometer-scale movements of the tympanic membrane (TM). These measurements can facilitate otologists' ability to study and diagnose hearing disorders in humans. The holographic platform consists of a laser delivery system and an otoscope. The control software, called LaserView, is written in Visual C++ and handles communication and synchronization between hardware components. It provides a user-friendly interface to allow viewing of holographic images with several tools to automate holography-related tasks and facilitate hardware communication. The software uses a series of concurrent threads to acquire images, control the hardware, and display quantitative holographic data at video rates and in two modes of operation: optoelectronic holography and lensless digital holography. The holographic platform has been used to perform experiments on several live and post-mortem specimens, and is to be deployed in a medical research environment with future developments leading to its eventual clinical use.

Microfluidic optoelectronic sensor for salivary diagnostics of stomach cancer.

Science.gov (United States)

Zilberman, Yael; Sonkusale, Sameer R

2015-05-15

We present a microfluidic optoelectronic sensor for saliva diagnostics with a potential application for non-invasive early diagnosis of stomach cancer. Stomach cancer is the second most common cause of cancer-related deaths in the world. The primary identified cause is infection by a gram-negative bacterium Helicobacter pylori. These bacteria secrete the enzyme urease that converts urea into carbon dioxide (CO2) and ammonia (NH3), leading to their elevated levels in breath and body fluids. The proposed optoelectronic sensor will detect clinically relevant levels of CO2 and NH3 in saliva that can potentially be used for early diagnosis of stomach cancer. The sensor is composed of the embedded in a microfluidic device array of microwells filled with ion-exchange polymer microbeads doped with various organic dyes. The optical response of this unique highly diverse sensor is monitored over a broad spectrum, which provides a platform for cross-reactive sensitivity and allows detection of CO2 and NH3 in saliva at ppm levels. Copyright © 2014 Elsevier B.V. All rights reserved.

Recent Achievements on Photovoltaic Optoelectronic Tweezers Based on Lithium Niobate

Directory of Open Access Journals (Sweden)

Angel García-Cabañes

2018-01-01

Full Text Available This review presents an up-dated summary of the fundamentals and applications of optoelectronic photovoltaic tweezers for trapping and manipulation of nano-objects on the surface of lithium niobate crystals. It extends the contents of previous reviews to cover new topics and developments which have emerged in recent years and are marking the trends for future research. Regarding the theoretical description of photovoltaic tweezers, detailed simulations of the electrophoretic and dielectrophoretic forces acting on different crystal configurations are discussed in relation to the structure of the obtained trapping patterns. As for the experimental work, we will pay attention to the manipulation and patterning of micro-and nanoparticles that has experimented an outstanding progress and relevant applications have been reported. An additional focus is now laid on recent work about micro-droplets, which is a central topic in microfluidics and optofluidics. New developments in biology and biomedicine also constitute a relevant part of the review. Finally, some topics partially related with photovoltaic tweezers and a discussion on future prospects and challenges are included.

Demonstration of an optoelectronic interconnect architecture for a parallel modified signed-digit adder and subtracter

Science.gov (United States)

Sun, Degui; Wang, Na-Xin; He, Li-Ming; Weng, Zhao-Heng; Wang, Daheng; Chen, Ray T.

1996-06-01

A space-position-logic-encoding scheme is proposed and demonstrated. This encoding scheme not only makes the best use of the convenience of binary logic operation, but is also suitable for the trinary property of modified signed- digit (MSD) numbers. Based on the space-position-logic-encoding scheme, a fully parallel modified signed-digit adder and subtractor is built using optoelectronic switch technologies in conjunction with fiber-multistage 3D optoelectronic interconnects. Thus an effective combination of a parallel algorithm and a parallel architecture is implemented. In addition, the performance of the optoelectronic switches used in this system is experimentally studied and verified. Both the 3-bit experimental model and the experimental results of a parallel addition and a parallel subtraction are provided and discussed. Finally, the speed ratio between the MSD adder and binary adders is discussed and the advantage of the MSD in operating speed is demonstrated.

Combination of silicon nitride and porous silicon induced optoelectronic features enhancement of multicrystalline silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Rabha, Mohamed Ben; Dimassi, Wissem; Gaidi, Mounir; Ezzaouia, Hatem; Bessais, Brahim [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

2011-06-15

The effects of antireflection (ARC) and surface passivation films on optoelectronic features of multicrystalline silicon (mc-Si) were investigated in order to perform high efficiency solar cells. A double layer consisting of Plasma Enhanced Chemical Vapor Deposition (PECVD) of silicon nitride (SiN{sub x}) on porous silicon (PS) was achieved on mc-Si surfaces. It was found that this treatment decreases the total surface reflectivity from about 25% to around 6% in the 450-1100 nm wavelength range. As a result, the effective minority carrier diffusion length, estimated from the Laser-beam-induced current (LBIC) method, was found to increase from 312 {mu}m for PS-treated cells to about 798 {mu}m for SiN{sub x}/PS-treated ones. The deposition of SiN{sub x} was found to impressively enhance the minority carrier diffusion length probably due to hydrogen passivation of surface, grain boundaries and bulk defects. Fourier Transform Infrared Spectroscopy (FTIR) shows that the vibration modes of the highly suitable passivating Si-H bonds exhibit frequency shifts toward higher wavenumber, depending on the x ratio of the introduced N atoms neighbors. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Graphene optoelectronics synthesis, characterization, properties, and applications

CERN Document Server

bin M Yusoff, Abdul Rashid

2014-01-01

This first book on emerging applications for this innovative material gives an up-to-date account of the many opportunities graphene offers high-end optoelectronics.The text focuses on potential as well as already realized applications, discussing metallic and passive components, such as transparent conductors and smart windows, as well as high-frequency devices, spintronics, photonics, and terahertz devices. Also included are sections on the fundamental properties, synthesis, and characterization of graphene. With its unique coverage, this book will be welcomed by materials scientists, solid-

Formation times of RbHe exciplexes on the surface of superfluid versus normal fluid helium nanodroplets

International Nuclear Information System (INIS)

Droppelmann, G.; Buenermann, O.; Stienkemeier, F.; Schulz, C.P.

2004-01-01

Nanodroplets of either superfluid He 4 or normal fluid He 3 are doped with Rb atoms that are bound to the surface of the droplets. The formation of RbHe exciplexes upon 5P 3/2 excitation is monitored in real time by femtosecond pump-probe techniques. We find formation times of 8.5 and 11.6 ps for Rb He 4 and Rb He 3 , respectively. A comparison to calculations based on a tunneling model introduced for these systems by Reho et al. [J. Chem. Phys. 113, 9694 (2000)] shows that the proposed mechanism cannot account for our findings. Apparently, a different relaxation dynamics of the superfluid opposed to the normal fluid surface is responsible for the observed formation times

Problems of systems dataware using optoelectronic measuring means of linear displacement

Science.gov (United States)

Bazykin, S. N.; Bazykina, N. A.; Samohina, K. S.

2017-10-01

Problems of the dataware of the systems with the use of optoelectronic means of the linear displacement are considered in the article. The classification of the known physical effects, realized by the means of information-measuring systems, is given. The organized analysis of information flows in technical systems from the standpoint of determination of inaccuracies of measurement and management was conducted. In spite of achieved successes in automation of machine-building and instruments-building equipment in the field of dataware of the technical systems, there are unresolved problems, concerning the qualitative aspect of the production process. It was shown that the given problem can be solved using optoelectronic lazer information-measuring systems. Such information-measuring systems are capable of not only executing the measuring functions, but also solving the problems of management and control during processing, thereby guaranteeing the quality of final products.

Identification of surface species by vibrational normal mode analysis. A DFT study

Science.gov (United States)

Zhao, Zhi-Jian; Genest, Alexander; Rösch, Notker

2017-10-01

Infrared spectroscopy is an important experimental tool for identifying molecular species adsorbed on a metal surface that can be used in situ. Often vibrational modes in such IR spectra of surface species are assigned and identified by comparison with vibrational spectra of related (molecular) compounds of known structure, e. g., an organometallic cluster analogue. To check the validity of this strategy, we carried out a computational study where we compared the normal modes of three C2Hx species (x = 3, 4) in two types of systems, as adsorbates on the Pt(111) surface and as ligands in an organometallic cluster compound. The results of our DFT calculations reproduce the experimental observed frequencies with deviations of at most 50 cm-1. However, the frequencies of the C2Hx species in both types of systems have to be interpreted with due caution if the coordination mode is unknown. The comparative identification strategy works satisfactorily when the coordination mode of the molecular species (ethylidyne) is similar on the surface and in the metal cluster. However, large shifts are encountered when the molecular species (vinyl) exhibits different coordination modes on both types of substrates.

Nanocellulose-based Translucent Diffuser for Optoelectronic Device Applications with Dramatic Improvement of Light Coupling.

Science.gov (United States)

Wu, Wei; Tassi, Nancy G; Zhu, Hongli; Fang, Zhiqiang; Hu, Liangbing

2015-12-09

Nanocellulose is a biogenerated and biorenewable organic material. Using a process based on 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)/NaClO/NaBr system, a highly translucent and light-diffusive film consisting of many layers of nanocellulose fibers and wood pulp microfibers was made. The film demonstrates a combination of large optical transmittance of ∼90% and tunable diffuse transmission of up to ∼78% across the visible and near-infrared spectra. The detailed characterizations of the film indicate the combination of high optical transmittance and haze is due to the film's large packing density and microstructured surface. The superior optical properties make the film a translucent light diffuser and applicable for improving the efficiencies of optoelectronic devices such as thin-film silicon solar cells and organic light-emitting devices.

Optoelectronic devices, low temperature preparation methods, and improved electron transport layers

KAUST Repository

Eita, Mohamed S.; El, Labban Abdulrahman; Usman, Anwar; Beaujuge, Pierre; Mohammed, Omar F.

2016-01-01

An optoelectronic device such as a photovoltaic device which has at least one layer, such as an electron transport layer, which comprises a plurality of alternating, oppositely charged layers including metal oxide layers. The metal oxide can be zinc

Enhanced Optoelectronic Performance of a Passivated Nanowire-Based Device: Key Information from Real-Space Imaging Using 4D Electron Microscopy

KAUST Repository

Khan, Jafar Iqbal

2016-03-03

Managing trap states and understanding their role in ultrafast charge-carrier dynamics, particularly at surface and interfaces, remains a major bottleneck preventing further advancements and commercial exploitation of nanowire (NW)-based devices. A key challenge is to selectively map such ultrafast dynamical processes on the surfaces of NWs, a capability so far out of reach of time-resolved laser techniques. Selective mapping of surface dynamics in real space and time can only be achieved by applying four-dimensional scanning ultrafast electron microscopy (4D S-UEM). Charge carrier dynamics are spatially and temporally visualized on the surface of InGaN NW arrays before and after surface passivation with octadecylthiol (ODT). The time-resolved secondary electron images clearly demonstrate that carrier recombination on the NW surface is significantly slowed down after ODT treatment. This observation is fully supported by enhancement of the performance of the light emitting device. Direct observation of surface dynamics provides a profound understanding of the photophysical mechanisms on materials\\' surfaces and enables the formulation of effective surface trap state management strategies for the next generation of high-performance NW-based optoelectronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

How Can Polarization States of Reflected Light from Snow Surfaces Inform Us on Surface Normals and Ultimately Snow Grain Size Measurements?

Science.gov (United States)

Schneider, A. M.; Flanner, M.; Yang, P.; Yi, B.; Huang, X.; Feldman, D.

2016-12-01

The Snow Grain Size and Pollution (SGSP) algorithm is a method applied to Moderate Resolution Imaging Spectroradiometer data to estimate snow grain size from space-borne measurements. Previous studies validate and quantify potential sources of error in this method, but because it assumes flat snow surfaces, however, large scale variations in surface normals can cause biases in its estimates due to its dependence on solar and observation zenith angles. To address these variations, we apply the Monte Carlo method for photon transport using data containing the single scattering properties of different ice crystals to calculate polarization states of reflected monochromatic light at 1500nm from modeled snow surfaces. We evaluate the dependence of these polarization states on solar and observation geometry at 1500nm because multiple scattering is generally a mechanism for depolarization and the ice crystals are relatively absorptive at this wavelength. Using 1500nm thus results in a higher number of reflected photons undergoing fewer scattering events, increasing the likelihood of reflected light having higher degrees of polarization. In evaluating the validity of the model, we find agreement with previous studies pertaining to near-infrared spectral directional hemispherical reflectance (i.e. black-sky albedo) and similarities in measured bidirectional reflectance factors, but few studies exist modeling polarization states of reflected light from snow surfaces. Here, we present novel results pertaining to calculated polarization states and compare dependences on solar and observation geometry for different idealized snow surfaces. If these dependencies are consistent across different ice particle shapes and sizes, then these findings could inform the SGSP algorithm by providing useful relationships between measurable physical quantities and solar and observation geometry to better understand variations in snow surface normals from remote sensing observations.

Distribution of Different Sized Ocular Surface Vessels in Diabetics and Normal Individuals.

Science.gov (United States)

Banaee, Touka; Pourreza, Hamidreza; Doosti, Hassan; Abrishami, Mojtaba; Ehsaei, Asieh; Basiry, Mohsen; Pourreza, Reza

2017-01-01

To compare the distribution of different sized vessels using digital photographs of the ocular surface of diabetic and normal individuals. In this cross-sectional study, red-free conjunctival photographs of diabetic and normal individuals, aged 30-60 years, were taken under defined conditions and analyzed using a Radon transform-based algorithm for vascular segmentation. The image areas occupied by vessels (AOV) of different diameters were calculated. The main outcome measure was the distribution curve of mean AOV of different sized vessels. Secondary outcome measures included total AOV and standard deviation (SD) of AOV of different sized vessels. Two hundred and sixty-eight diabetic patients and 297 normal (control) individuals were included, differing in age (45.50 ± 5.19 vs. 40.38 ± 6.19 years, P distribution curves of mean AOV differed between patients and controls (smaller AOV for larger vessels in patients; P distribution curve of vessels compared to controls. Presence of diabetes mellitus is associated with contraction of larger vessels in the conjunctiva. Smaller vessels dilate with diabetic retinopathy. These findings may be useful in the photographic screening of diabetes mellitus and retinopathy.

Nanopatterned Metallic Films for Use As Transparent Conductive Electrodes in Optoelectronic Devices

KAUST Repository

Catrysse, Peter B.; Fan, Shanhui

2010-01-01

We investigate the use of nanopatterned metallic films as transparent conductive electrodes in optoelectronic devices. We find that the physics of nanopatterned electrodes, which are often optically thin metallic films, differs from

Measuring processes with opto-electronic semiconductor components

International Nuclear Information System (INIS)

1985-01-01

This is a report on the state of commercially available semiconductor emitters and detectors for the visible, near, middle and remote infrared range. A survey is given on the distance, speed, flow and length measuring techniques using opto-electronic components. Automatic focussing, the use of light barriers, non-contact temperature measurements, spectroscopic gas, liquid and environmental measurement techniques and gas analysis in medical techniques show further applications of the new components. The modern concept of guided radiation in optical fibres and their use in system technology is briefly explained. (DG) [de

Smart Optoelectronic Sensors and Intelligent Sensor Systems

Directory of Open Access Journals (Sweden)

Sergey Y. YURISH

2012-03-01

Full Text Available Light-to-frequency converters are widely used in various optoelectronic sensor systems. However, a further frequency-to-digital conversion is a bottleneck in such systems due to a broad frequency range of light-to-frequency converters’ outputs. This paper describes an effective OEM design approach, which can be used for smart and intelligent sensor systems design. The design is based on novel, multifunctional integrated circuit of Universal Sensors & Transducers Interface especially designed for such sensor applications. Experimental results have confirmed an efficiency of this approach and high metrological performances.

Free-standing optoelectronic graphene-CdS-graphene oxide composite paper produced by vacuum-assisted self-assembly

Energy Technology Data Exchange (ETDEWEB)

Li, Yong-Feng [Chinese Academy of Sciences, Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Taiyuan (China); Graduate University of Chinese Academy of Sciences, Beijing (China); Liu, Yan-Zhen; Shen, Wen-Zhong; Yang, Yong-Gang; Wang, Mao-Zhang [Chinese Academy of Sciences, Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Taiyuan (China); Wen, Yue-Fang [Zhejiang University, Department of Chemical and Biological Engineering, Hangzhou (China)

2012-03-15

Free-standing optoelectronic graphene-CdS-graphene oxide (G-CdS-GO) composite papers were prepared by vacuum-assisted self-assembly. G-CdS hybrids were first prepared by a hydrothermal method and GO acts as a dispersant which makes it easier to disperse them to form relatively stable aqueous suspensions for fabricating paper. Transmission electron microscopy shows that CdS quantum dots (QDs) with an average size of approximately 1-2 nm were distributed uniformly on the graphene sheets. Photoluminescence measurements for the as-prepared G-CdS-GO composite paper showed that the surface defect related emissions of attached CdS QDs decrease and blue shift obviously due to the change in particle size and the interaction of the surface of the CdS QDs with both the GO and the graphene sheets. The resulting paper holds great potential for applications in thin film solar cells, sensors, diodes, and so on. (orig.)

Surface plasmon resonance application for herbicide detection

Science.gov (United States)

Chegel, Vladimir I.; Shirshov, Yuri M.; Piletskaya, Elena V.; Piletsky, Sergey A.

1998-01-01

The optoelectronic biosensor, based on Surface Plasmon Resonance (SPR) for detection of photosynthesis-inhibiting herbicides in aqueous solutions is presented. The pesticide capability to replace plastoquinone from its complex with D1 protein is used for the detection. This replacement reaction results in the changes of the optical characteristics of protein layer, immobilized on the gold surface. Monitoring of these changes with SPR-technique permit to determine 0.1 - 5.0 mkg/ml herbicide in solution within one hour.

Research surface resistance of copper normal and abnormal skin-effects depending on the frequency of electromagnetic field

International Nuclear Information System (INIS)

Kutovyi, V.A.; Komir, A.I.

2013-01-01

The results of the frequency dependence of surface resistance of copper in diffuse and specular reflection of electrons from the conductive surface of the high-frequency resonance of the system depending on the frequency of the electromagnetic field in the normal and anomalous skin effect. Found, the surface resistance of copper is reduced by more than 10 times at the temperature of liquid helium, as compared with a surface resistivity at room temperature, at frequencies f ≤ 173 MHz, for diffuse reflection of conduction electrons from the surface of the conductive layer, and the specular reflection - at frequencies f ≤ 346 MHz

Design of a dual-axis optoelectronic level for precision angle measurements

International Nuclear Information System (INIS)

Fan, Kuang-Chao; Wang, Tsung-Han; Lin, Sheng-Yi; Liu, Yen-Chih

2011-01-01

The accuracy of machine tools is mainly determined by angular errors during linear motion according to the well-known Abbe principle. Precision angle measurement is important to precision machines. This paper presents the theory and experiments of a new dual-axis optoelectronic level with low cost and high precision. The system adopts a commercial DVD pickup head as the angle sensor in association with the double-layer pendulum mechanism for two-axis swings, respectively. In data processing with a microprocessor, the measured angles of both axes can be displayed on an LCD or exported to an external PC. Calibrated by a triple-beam laser angular interferometer, the error of the dual-axis optoelectronic level is better than ±0.7 arcsec in the measuring range of ±30 arcsec, and the settling time is within 0.5 s. Experiments show the applicability to the inspection of precision machines

State-of-the-art photodetectors for optoelectronic integration at telecommunication wavelength

Directory of Open Access Journals (Sweden)

Eng Png Ching

2015-01-01

Full Text Available Photodetectors hold a critical position in optoelectronic integrated circuits, and they convert light into electricity. Over the past decades, high-performance photodetectors (PDs have been aggressively pursued to enable high-speed, large-bandwidth, and low-noise communication applications. Various material systems have been explored and different structures designed to improve photodetection capability as well as compatibility with CMOS circuits. In this paper, we review state-of-theart photodetection technologies in the telecommunications spectrum based on different material systems, including traditional semiconductors such as InGaAs, Si, Ge and HgCdTe, as well as recently developed systems such as low-dimensional materials (e.g. graphene, carbon nanotube, etc. and noble metal plasmons. The corresponding material properties, fundamental mechanisms, fabrication, theoretical modelling and performance of the typical PDs are presented, including the emerging directions and perspectives of the PDs for optoelectronic integration applications are discussed.

Reconfigurable Integrated Optoelectronics

Directory of Open Access Journals (Sweden)

Richard Soref

2011-01-01

Full Text Available Integrated optics today is based upon chips of Si and InP. The future of this chip industry is probably contained in the thrust towards optoelectronic integrated circuits (OEICs and photonic integrated circuits (PICs manufactured in a high-volume foundry. We believe that reconfigurable OEICs and PICs, known as ROEICs and RPICs, constitute the ultimate embodiment of integrated photonics. This paper shows that any ROEIC-on-a-chip can be decomposed into photonic modules, some of them fixed and some of them changeable in function. Reconfiguration is provided by electrical control signals to the electro-optical building blocks. We illustrate these modules in detail and discuss 3D ROEIC chips for the highest-performance signal processing. We present examples of our module theory for RPIC optical lattice filters already constructed, and we propose new ROEICs for directed optical logic, large-scale matrix switching, and 2D beamsteering of a phased-array microwave antenna. In general, large-scale-integrated ROEICs will enable significant applications in computing, quantum computing, communications, learning, imaging, telepresence, sensing, RF/microwave photonics, information storage, cryptography, and data mining.

Modeling of normal contact of elastic bodies with surface relief taken into account

Science.gov (United States)

Goryacheva, I. G.; Tsukanov, I. Yu

2018-04-01

An approach to account the surface relief in normal contact problems for rough bodies on the basis of an additional displacement function for asperities is considered. The method and analytic expressions for calculating the additional displacement function for one-scale and two-scale wavy relief are presented. The influence of the microrelief geometric parameters, including the number of scales and asperities density, on additional displacements of the rough layer is analyzed.

Biotunable Nanoplasmonic Filter on Few-Layer MoS2 for Rapid and Highly Sensitive Cytokine Optoelectronic Immunosensing.

Science.gov (United States)

Park, Younggeun; Ryu, Byunghoon; Oh, Bo-Ram; Song, Yujing; Liang, Xiaogan; Kurabayashi, Katsuo

2017-06-27

Monitoring of the time-varying immune status of a diseased host often requires rapid and sensitive detection of cytokines. Metallic nanoparticle-based localized surface plasmon resonance (LSPR) biosensors hold promise to meet this clinical need by permitting label-free detection of target biomolecules. These biosensors, however, continue to suffer from relatively low sensitivity as compared to conventional immunoassay methods that involve labeling processes. Their response speeds also need to be further improved to enable rapid cytokine quantification for critical care in a timely manner. In this paper, we report an immunobiosensing device integrating a biotunable nanoplasmonic optical filter and a highly sensitive few-layer molybdenum disulfide (MoS 2 ) photoconductive component, which can serve as a generic device platform to meet the need of rapid cytokine detection with high sensitivity. The nanoplasmonic filter consists of anticytokine antibody-conjugated gold nanoparticles on a SiO 2 thin layer that is placed 170 μm above a few-layer MoS 2 photoconductive flake device. The principle of the biosensor operation is based on tuning the delivery of incident light to the few-layer MoS 2 photoconductive flake thorough the nanoplasmonic filter by means of biomolecular surface binding-induced LSPR shifts. The tuning is dependent on cytokine concentration on the nanoplasmonic filter and optoelectronically detected by the few-layer MoS 2 device. Using the developed optoelectronic biosensor, we have demonstrated label-free detection of IL-1β, a pro-inflammatory cytokine, with a detection limit as low as 250 fg/mL (14 fM), a large dynamic range of 10 6 , and a short assay time of 10 min. The presented biosensing approach could be further developed and generalized for point-of-care diagnosis, wearable bio/chemical sensing, and environmental monitoring.

Optoelectronic polarimeter controlled by a graphical user interface of Matlab

International Nuclear Information System (INIS)

Vilardy, J M; Torres, R; Jimenez, C J

2017-01-01

We show the design and implementation of an optical polarimeter using electronic control. The polarimeter has a software with a graphical user interface (GUI) that controls the optoelectronic setup and captures the optical intensity measurement, and finally, this software evaluates the Stokes vector of a state of polarization (SOP) by means of the synchronous detection of optical waves. The proposed optoelectronic polarimeter can determine the Stokes vector of a SOP in a rapid and efficient way. Using the polarimeter proposed in this paper, the students will be able to observe (in an optical bench) and understand the different interactions of the SOP when the optical waves pass through to the linear polarizers and retarder waves plates. The polarimeter prototype could be used as a main tool for the students in order to learn the theory and experimental aspects of the SOP for optical waves via the Stokes vector measurement. The proposed polarimeter controlled by a GUI of Matlab is more attractive and suitable to teach and to learn the polarization of optical waves. (paper)

Study and practice of flipped classroom in optoelectronic technology curriculum

Science.gov (United States)

Shi, Jianhua; Lei, Bing; Liu, Wei; Yao, Tianfu; Jiang, Wenjie

2017-08-01

"Flipped Classroom" is one of the most popular teaching models, and has been applied in more and more curriculums. It is totally different from the traditional teaching model. In the "Flipped Classroom" model, the students should watch the teaching video afterschool, and in the classroom only the discussion is proceeded to improve the students' comprehension. In this presentation, "Flipped Classroom" was studied and practiced in opto-electronic technology curriculum; its effect was analyzed by comparing it with the traditional teaching model. Based on extensive and deep investigation, the phylogeny, the characters and the important processes of "Flipped Classroom" are studied. The differences between the "Flipped Classroom" and the traditional teaching model are demonstrated. Then "Flipped Classroom" was practiced in opto-electronic technology curriculum. In order to obtain high effectiveness, a lot of teaching resources were prepared, such as the high-quality teaching video, the animations and the virtual experiments, the questions that the students should finish before and discussed in the class, etc. At last, the teaching effect was evaluated through analyzing the result of the examination and the students' surveys.

Filterless low-phase-noise frequency-quadrupled microwave generation based on a multimode optoelectronic oscillator

Science.gov (United States)

Teng, Yichao; Zhang, Pin; Zhang, Baofu; Chen, Yiwang

2018-02-01

A scheme to realize low-phase-noise frequency-quadrupled microwave generation without any filter is demonstrated. In this scheme, a multimode optoelectronic oscillator is mainly contributed by dual-parallel Mach-Zehnder modulators, fiber, photodetector, and microwave amplifier. The local source signal is modulated by a child MZM (MZMa), which is worked at maximum transmission point. Through properly adjusting the bias voltages of the other child MZM (MZMb) and the parent MZM (MZMc), optical carrier is effectively suppressed and second sidebands are retained, then the survived optical signal is fed back to the photodetector and MZMb to form an optoelectronic hybrid resonator and realize frequency-quadrupled signal generation. Due to the high Q-factor and mode selection effect of the optoelectronic hybrid resonator, compared with the source signal, the generated frequency-quadrupled signal has a lower phase noise. The approach has verified by experiments, and 18, 22, and 26 GHz frequency-quadrupled signal are generated by 4.5, 5.5, and 6.5 GHz local source signals. Compared with 4.5 GHz source signal, the phase noise of generated 18 GHz signal at 10 kHz frequency offset has 26.5 dB reduction.

Integrated NEMS and optoelectronics for sensor applications.

Energy Technology Data Exchange (ETDEWEB)

Czaplewski, David A.; Serkland, Darwin Keith; Olsson, Roy H., III; Bogart, Gregory R. (Symphony Acoustics, Rio Rancho, NM); Krishnamoorthy, Uma; Warren, Mial E.; Carr, Dustin Wade (Symphony Acoustics, Rio Rancho, NM); Okandan, Murat; Peterson, Kenneth Allen

2008-01-01

This work utilized advanced engineering in several fields to find solutions to the challenges presented by the integration of MEMS/NEMS with optoelectronics to realize a compact sensor system, comprised of a microfabricated sensor, VCSEL, and photodiode. By utilizing microfabrication techniques in the realization of the MEMS/NEMS component, the VCSEL and the photodiode, the system would be small in size and require less power than a macro-sized component. The work focused on two technologies, accelerometers and microphones, leveraged from other LDRD programs. The first technology was the nano-g accelerometer using a nanophotonic motion detection system (67023). This accelerometer had measured sensitivity of approximately 10 nano-g. The Integrated NEMS and optoelectronics LDRD supported the nano-g accelerometer LDRD by providing advanced designs for the accelerometers, packaging, and a detection scheme to encapsulate the accelerometer, furthering the testing capabilities beyond bench-top tests. A fully packaged and tested die was never realized, but significant packaging issues were addressed and many resolved. The second technology supported by this work was the ultrasensitive directional microphone arrays for military operations in urban terrain and future combat systems (93518). This application utilized a diffraction-based sensing technique with different optical component placement and a different detection scheme from the nano-g accelerometer. The Integrated NEMS LDRD supported the microphone array LDRD by providing custom designs, VCSELs, and measurement techniques to accelerometers that were fabricated from the same operational principles as the microphones, but contain proof masses for acceleration transduction. These devices were packaged at the end of the work.

Normal appearance of the prostate and seminal tract: MR imaging using an endorectal surface coil

International Nuclear Information System (INIS)

Kim, Myeong Jin; Lee, Jong Tae; Lee, Moo Sang; Choi, Pil Sik; Hong, Sung Joon; Lee, Yeon Hee; Choi, Hak Yong

1994-01-01

To assess the ability of MR imaging with an endorectal surface coil for the depiction of normal anatomical structure of prostate and its adjacent organs. MR imaging using an endorectal surface coil was performed in 23 male patients(age ; 20-75) to evaluate various prostatic and vasovesicular disorders, i. e, 14 cases of ejaculatory problems, 3 cases of hypogonadism, and 4 cases of prostatic cancers and 2 cases of benign prostatic hyperplasia. MR images were obtained with axial, sagittal and coronal fast spin echo long TR/TE images and axial spin echo short TR/TE images. Field of views was 10-12 cm and scan thickness was 3-5 mm. Depiction of normal anatomcial structures was excellent in all cases. On T2WI, zonal anatomy of the prostate and prostatic urethra, urethral crest, and ejaculatory duct were cleary visualized. On T1WI, periprostatic fat plane is more cleary visualized. On transverse images, periprostatic structures were well visualized on T1WI,and on T2WI, anterior fibromuscular stroma, transition zone and peripheral zone could be readily differentiated. Coronal images were more helpful in visualization of both central and peripheral zones. Vas deferens, ejaculatory duct and vermontanum were also more easily defined on these images. Sagittal images was helpful in the depiction of anterior fibromuscular stroma, central zone and peripheral zone with prostatic urethra and ejaculatory duct in a single plane. High resolution MR imaging with an endorectal surface coil can readily visualize the normal anatomy of the prostate and its related structures and may be useful in the evaluation of various diseases of prostate and vasvesicular system

Normal appearance of the prostate and seminal tract: MR imaging using an endorectal surface coil

Energy Technology Data Exchange (ETDEWEB)

Kim, Myeong Jin; Lee, Jong Tae; Lee, Moo Sang; Choi, Pil Sik; Hong, Sung Joon; Lee, Yeon Hee; Choi, Hak Yong [Yonsei University College of Medicine, Seoul (Korea, Republic of)

1994-06-15

To assess the ability of MR imaging with an endorectal surface coil for the depiction of normal anatomical structure of prostate and its adjacent organs. MR imaging using an endorectal surface coil was performed in 23 male patients(age ; 20-75) to evaluate various prostatic and vasovesicular disorders, i. e, 14 cases of ejaculatory problems, 3 cases of hypogonadism, and 4 cases of prostatic cancers and 2 cases of benign prostatic hyperplasia. MR images were obtained with axial, sagittal and coronal fast spin echo long TR/TE images and axial spin echo short TR/TE images. Field of views was 10-12 cm and scan thickness was 3-5 mm. Depiction of normal anatomcial structures was excellent in all cases. On T2WI, zonal anatomy of the prostate and prostatic urethra, urethral crest, and ejaculatory duct were cleary visualized. On T1WI, periprostatic fat plane is more cleary visualized. On transverse images, periprostatic structures were well visualized on T1WI,and on T2WI, anterior fibromuscular stroma, transition zone and peripheral zone could be readily differentiated. Coronal images were more helpful in visualization of both central and peripheral zones. Vas deferens, ejaculatory duct and vermontanum were also more easily defined on these images. Sagittal images was helpful in the depiction of anterior fibromuscular stroma, central zone and peripheral zone with prostatic urethra and ejaculatory duct in a single plane. High resolution MR imaging with an endorectal surface coil can readily visualize the normal anatomy of the prostate and its related structures and may be useful in the evaluation of various diseases of prostate and vasvesicular system.

Modification of the optoelectronic properties of two-dimensional MoS2 crystals by ultraviolet-ozone treatment

Science.gov (United States)

Yang, Hae In; Park, Seonyoung; Choi, Woong

2018-06-01

We report the modification of the optoelectronic properties of mechanically-exfoliated single layer MoS2 by ultraviolet-ozone exposure. Photoluminescence emission of pristine MoS2 monotonically decreased and eventually quenched as ultraviolet-ozone exposure time increased from 0 to 10 min. The reduction of photoluminescence emission accompanied reduction of Raman modes, suggesting structural degradation in ultraviolet-ozone exposed MoS2. Analysis with X-ray photoelectron spectroscopy revealed that the formation of Ssbnd O and Mosbnd O bonding increases with ultraviolet-ozone exposure time. Measurement of electrical transport properties of MoS2 in a bottom-gate thin-film transistor configuration suggested the presence of insulating MoO3 after ultraviolet-ozone exposure. These results demonstrate that ultraviolet-ozone exposure can significantly influence the optoelectronic properties of single layer MoS2, providing important implications on the application of MoS2 and other two-dimensional materials into optoelectronic devices.

Effect of annealing over optoelectronic properties of graphene based transparent electrodes

Energy Technology Data Exchange (ETDEWEB)

Yadav, Shriniwas, E-mail: sniwas89@gmail.com; Kaur, Inderpreet, E-mail: inderpreety@yahoo.co.in [Academy of Scientific and Innovative Research- Central Scientific Instruments Organisation (AcSIR-CSIO), Sector-30C, Chandigarh (India); Council of Scientific and Industrial Research- Central Scientific Instruments Organisation (CSIR-CSIO), Sector-30C, Chandigarh (India)

2016-04-13

Graphene, an atom–thick two dimensional graphitic material have led various fundamental breakthroughs in the field of science and technology. Due to their exceptional optical, physical and electrical properties, graphene based transparent electrodes have shown several applications in organic light emitting diodes, solar cells and thin film transistors. Here, we are presenting effect of annealing over optoelectronic properties of graphene based transparent electrodes. Graphene based transparent electrodes have been prepared by wet chemical approach over glass substrates. After fabrication, these electrodes tested for optical transmittance in visible region. Sheet resistance was measured using four probe method. Effect of thermal annealing at 200 °C was studied over optical and electrical performance of these electrodes. Optoelectronic performance was judged from ratio of direct current conductivity to optical conductivity (σ{sub dc}/σ{sub opt}) as a figure of merit for transparent conductors. The fabricated electrodes display good optical and electrical properties. Such electrodes can be alternatives for doped metal oxide based transparent electrodes.

Optoelectronic studies on heterocyclic bases of deoxyribonucleic acid for DNA photonics.

Science.gov (United States)

El-Diasty, Fouad; Abdel-Wahab, Fathy

2015-10-01

The optoelectronics study of large molecules, particularly π-stacking molecules, such as DNA is really an extremely difficult task. We perform first electronic structure calculations on the heterocyclic bases of 2'-deoxyribonucleic acid based on Lorentz-Fresnel dispersion theory. In the UV-VIS range of spectrum, many of the optoelectronic parameters for DNA four bases namely adenine, guanine, cytosine and thymine are calculated and discussed. The results demonstrate that adenine has the highest hyperpolarizability, whereas thymine has the lowest hyperpolarizability. Cytosine has the lower average oscillator energy and the higher lattice energy. Thymine infers the most stable nucleic base with the lower phonon energy. Thymine also has the highest average oscillator energy and the lower lattice energy. Moreover, the four nucleic acid bases have large band gap energies less than 5 eV with a semiconducting behavior. Guanine shows the smallest band gap and the highest Fermi level energy, whereas adenine elucidates the highest band gap energy. Copyright © 2015. Published by Elsevier B.V.

Effect of annealing over optoelectronic properties of graphene based transparent electrodes

Science.gov (United States)

Yadav, Shriniwas; Kaur, Inderpreet

2016-04-01

Graphene, an atom-thick two dimensional graphitic material have led various fundamental breakthroughs in the field of science and technology. Due to their exceptional optical, physical and electrical properties, graphene based transparent electrodes have shown several applications in organic light emitting diodes, solar cells and thin film transistors. Here, we are presenting effect of annealing over optoelectronic properties of graphene based transparent electrodes. Graphene based transparent electrodes have been prepared by wet chemical approach over glass substrates. After fabrication, these electrodes tested for optical transmittance in visible region. Sheet resistance was measured using four probe method. Effect of thermal annealing at 200 °C was studied over optical and electrical performance of these electrodes. Optoelectronic performance was judged from ratio of direct current conductivity to optical conductivity (σdc/σopt) as a figure of merit for transparent conductors. The fabricated electrodes display good optical and electrical properties. Such electrodes can be alternatives for doped metal oxide based transparent electrodes.

Tetracene-based organic light-emitting transistors: optoelectronic properties and electron injection mechanism

NARCIS (Netherlands)

Santato, C.; Capelli, R.; Loi, M.A.; Murgia, M.; Cicoira, F.; Roy, Arunesh; Stallinga, P; Zamboni, R.; Rost, C.; Karg, S.F.; Muccini, M.

2004-01-01

Optoelectronic properties of light-emitting field-effect transistors (LETs) fabricated on bottom-contact transistor structures using a tetracene film as charge-transport and light-emitting material are investigated. Electroluminescence generation and transistor current are correlated, and the bias

3D modeling to characterize lamina cribrosa surface and pore geometries using in vivo images from normal and glaucomatous eyes

Science.gov (United States)

Sredar, Nripun; Ivers, Kevin M.; Queener, Hope M.; Zouridakis, George; Porter, Jason

2013-01-01

En face adaptive optics scanning laser ophthalmoscope (AOSLO) images of the anterior lamina cribrosa surface (ALCS) represent a 2D projected view of a 3D laminar surface. Using spectral domain optical coherence tomography images acquired in living monkey eyes, a thin plate spline was used to model the ALCS in 3D. The 2D AOSLO images were registered and projected onto the 3D surface that was then tessellated into a triangular mesh to characterize differences in pore geometry between 2D and 3D images. Following 3D transformation of the anterior laminar surface in 11 normal eyes, mean pore area increased by 5.1 ± 2.0% with a minimal change in pore elongation (mean change = 0.0 ± 0.2%). These small changes were due to the relatively flat laminar surfaces inherent in normal eyes (mean radius of curvature = 3.0 ± 0.5 mm). The mean increase in pore area was larger following 3D transformation in 4 glaucomatous eyes (16.2 ± 6.0%) due to their more steeply curved laminar surfaces (mean radius of curvature = 1.3 ± 0.1 mm), while the change in pore elongation was comparable to that in normal eyes (−0.2 ± 2.0%). This 3D transformation and tessellation method can be used to better characterize and track 3D changes in laminar pore and surface geometries in glaucoma. PMID:23847739

Comparing of γ-ray, proton and neutron radiation effects on optoelectronics for space

International Nuclear Information System (INIS)

Yu Qingkui; Tang Min; Meng Meng; Li Pengwei; Wen Ping; Li Haian; Tang Jiesen; Wang Sixin; Song Yamei

2014-01-01

We performed irradiation test on optoelectronics with γ-rays, proton and neutron. The electrical measurements were performed pre and after irradiation. The degradations induced by each radiation source was compared. (authors)

Temperature Dependent Surface Structures and Electronic Properties of Organic-Inorganic Hybrid Perovskite Single Crystals

Science.gov (United States)

Jao, M.-H.; Teague, M. L.; Huang, J.-S.; Tseng, W.-S.; Yeh, N.-C.

Organic-inorganic hybrid perovskites, arising from research of low-cost high performance photovoltaics, have become promising materials not only for solar cells but also for various optoelectronic and spintronic applications. An interesting aspect of the hybrid perovskites is that their material properties, such as the band gap, can be easily tuned by varying the composition, temperature, and the crystalline phases. Additionally, the surface structure is critically important for their optoelectronic applications. It is speculated that different crystalline facets could show different trap densities, thus resulting in microscopically inhomogeneous performance. Here we report direct studies of the surface structures and electronic properties of hybrid perovskite CH3NH3PbI3 single crystals by scanning tunneling microscopy and spectroscopy (STM/STS). We found long-range spatially homogeneous tunneling conductance spectra with a well-defined energy gap of (1.55 +/- 0.1) eV at 300 K in the tetragonal phase, suggesting high quality of the single crystals. The energy gap increased to (1.81 +/- 0.1) eV in the orthorhombic phase, below the tetragonal-to-orthorhombic phase transition temperature at 150 K. Detailed studies of the temperature evolution in the spatially resolved surface structures and local density of states will be discussed to elucidate how these properties may influence the optoelectronic performance of the hybrid perovskites. We thank the support from NTU in Taiwan and from NSF in the US.

Superacid Passivation of Crystalline Silicon Surfaces.

Science.gov (United States)

Bullock, James; Kiriya, Daisuke; Grant, Nicholas; Azcatl, Angelica; Hettick, Mark; Kho, Teng; Phang, Pheng; Sio, Hang C; Yan, Di; Macdonald, Daniel; Quevedo-Lopez, Manuel A; Wallace, Robert M; Cuevas, Andres; Javey, Ali

2016-09-14

The reduction of parasitic recombination processes commonly occurring within the silicon crystal and at its surfaces is of primary importance in crystalline silicon devices, particularly in photovoltaics. Here we explore a simple, room temperature treatment, involving a nonaqueous solution of the superacid bis(trifluoromethane)sulfonimide, to temporarily deactivate recombination centers at the surface. We show that this treatment leads to a significant enhancement in optoelectronic properties of the silicon wafer, attaining a level of surface passivation in line with state-of-the-art dielectric passivation films. Finally, we demonstrate its advantage as a bulk lifetime and process cleanliness monitor, establishing its compatibility with large area photoluminescence imaging in the process.

Surface passivation of nano-textured fluorescent SiC by atomic layer deposited TiO2

DEFF Research Database (Denmark)

Lu, Weifang; Ou, Yiyu; Jokubavicius, Valdas

2016-01-01

Nano-textured surfaces have played a key role in optoelectronic materials to enhance the light extraction efficiency. In this work, morphology and optical properties of nano-textured SiC covered with atomic layer deposited (ALD) TiO2 were investigated. In order to obtain a high quality surface fo...

Effect of methyl substitution on optoelectronic properties of 1,3,6,8-tetraphenyl pyrenes

Directory of Open Access Journals (Sweden)

LIU Yanling

2014-06-01

Full Text Available Geometric structures of the ground states and excited states,frontier molecular orbitals,ionization potentials,electron affinities,reorganization energies,and absorption and emission spectra of three novel methyl-substituted 1,3,6,8-tetra-phenylpyrenes were studied theoretically by quantum-chemical methods,such as density functional theory (DFT.The results show that the position of methyl substituent on benzene ring has much effect on the optoelectronic properties of methyl-substituted 1,3,6,8-tetra-phenylpyrenes.Interestingly,the geometric structures and optoelectronic properties of the designed compound 1,3,6,8-tetra-p-tolylpyrene (TPPy are similar to those of 1,3,6,8-tetrakis(3,5-dimethylphenylpyrene (TDMPPy,which is worthy of being further researched.

Extreme Radiation Hardness and Space Qualification of AlGaN Optoelectronic Devices

International Nuclear Information System (INIS)

Sun, Ke-Xun; MacNeil, Lawrence; Balakrishnan, Kathik; Hultgren, Eric; Goebel, John; Bilenko, Yuri; Yang, Jinwei; Sun, Wenhong; Shatalov, Max; Hu, Xuhong; Gaska, Remis

2010-01-01

Unprecedented radiation hardness and environment robustness are required in the new generation of high energy density physics (HEDP) experiments and deep space exploration. National Ignition Facility (NIF) break-even shots will have a neutron yield of 10 15 or higher. The Europa Jupiter System Mission (EJSM) mission instruments will be irradiated with a total fluence of 10 12 protons/cm 2 during the space journey. In addition, large temperature variations and mechanical shocks are expected in these applications under extreme conditions. Hefty radiation and thermal shields are required for Si and GaAs based electronics and optoelectronics devices. However, for direct illumination and imaging applications, shielding is not a viable option. It is an urgent task to search for new semiconductor technologies and to develop radiation hard and environmentally robust optoelectronic devices. We will report on our latest systematic experimental studies on radiation hardness and space qualifications of AlGaN optoelectronic devices: Deep UV Light Emitting Diodes (DUV LEDs) and solarblind UV Photodiodes (PDs). For custom designed AlGaN DUV LEDs with a central emission wavelength of 255 nm, we have demonstrated its extreme radiation hardness up to 2 x 10 12 protons/cm 2 with 63.9 MeV proton beams. We have demonstrated an operation lifetime of over 26,000 hours in a nitrogen rich environment, and 23,000 hours of operation in vacuum without significant power drop and spectral shift. The DUV LEDs with multiple packaging styles have passed stringent space qualifications with 14 g random vibrations, and 21 cycles of 100K temperature cycles. The driving voltage, current, emission spectra and optical power (V-I-P) operation characteristics exhibited no significant changes after the space environmental tests. The DUV LEDs will be used for photoelectric charge management in space flights. For custom designed AlGaN UV photodiodes with a central response wavelength of 255 nm, we have

Nanostructure of highly aromatic graphene nanosheets -- From optoelectronics to electrochemical energy storage applications

Science.gov (United States)

Biswas, Sanjib

The exceptional electrical properties along with intriguing physical and chemical aspects of graphene nanosheets can only be realized by nanostructuring these materials through the homogeneous and orderly distribution of these nanosheets without compromising the aromaticity of the native basal plane. Graphene nanosheets prepared by direct exfoliation as opposed to the graphene oxide route are necessary in order to preserve the native chemical properties of graphene basal planes. This research has been directed at optimally combining the diverse physical and chemical aspects of graphene nanosheets such as particle size, surface area and edge chemistry to fabricate nanostructured architectures for optoelectronics and high power electrochemical energy storage applications. In the first nanostructuring effort, a monolayer of these ultrathin, highly hydrophobic graphene nanosheets was prepared on a large area substrate via self-assembly at the liquid-liquid interface. Driven by the minimization of interfacial energy these planar graphene nanosheets produce a close packed monolayer structure at the liquid-liquid interface. The resulting monolayer film exhibits high electrical conductivity of more than 1000 S/cm and an optical transmission of more than 70-80% between wavelengths of 550 nm and 2000 nm making it an ideal candidate for optoelectronic applications. In the second part of this research, nanostructuring was used to create a configuration suitable for supercapacitor applications. A free standing, 100% binder free multilayer, flexible film consisting of monolayers of graphene nanosheets was prepared by utilizing the van der Waals forces of attraction between the basal plans of the graphene nanosheets coupled with capillary driven and drying-induced collapse. A major benefit in this approach is that the graphene nanosheet's attractive physical and chemical characteristics can be synthesized into an architecture consisting of large and small nanosheets to create an

Navier-Stokes Computations of a Wing-Flap Model With Blowing Normal to the Flap Surface

Science.gov (United States)

Boyd, D. Douglas, Jr.

2005-01-01

A computational study of a generic wing with a half span flap shows the mean flow effects of several blown flap configurations. The effort compares and contrasts the thin-layer, Reynolds averaged, Navier-Stokes solutions of a baseline wing-flap configuration with configurations that have blowing normal to the flap surface through small slits near the flap side edge. Vorticity contours reveal a dual vortex structure at the flap side edge for all cases. The dual vortex merges into a single vortex at approximately the mid-flap chord location. Upper surface blowing reduces the strength of the merged vortex and moves the vortex away from the upper edge. Lower surface blowing thickens the lower shear layer and weakens the merged vortex, but not as much as upper surface blowing. Side surface blowing forces the lower surface vortex farther outboard of the flap edge by effectively increasing the aerodynamic span of the flap. It is seen that there is no global aerodynamic penalty or benefit from the particular blowing configurations examined.

Arrays of surface-normal electroabsorption modulators for the generation and signal processing of microwave photonics signals

NARCIS (Netherlands)

Noharet, Bertrand; Wang, Qin; Platt, Duncan; Junique, Stéphane; Marpaung, D.A.I.; Roeloffzen, C.G.H.

2011-01-01

The development of an array of 16 surface-normal electroabsorption modulators operating at 1550nm is presented. The modulator array is dedicated to the generation and processing of microwave photonics signals, targeting a modulation bandwidth in excess of 5GHz. The hybrid integration of the

Study of Optoelectronics Properties of Anisotropic Semiconductor Compounds with Ordered Stochiometric Vacancy

National Research Council Canada - National Science Library

Roud, Iouri

2004-01-01

This report results from a contract tasking loffe Institute as follows: The main aim of the project is to carry out basic research on optoelectronic properties of CdGeAs2 and (Zn,Cd,Hg)(Ga,Al,ln)2(S,Se,Te...

Normalization in quantitative [18F]FDG PET imaging: the 'body surface area' may be a volume

International Nuclear Information System (INIS)

Laffon, Eric; Suarez, Kleydis; Berthoumieu, Yannick; Ducassou, Dominique; Marthan, Roger

2006-01-01

Non-invasive methods for quantifying [ 18 F]FDG uptake in tumours often require normalization to either body weight or body surface area (BSA), as a surrogate for [ 18 F]FDG distribution volume (DV). Whereas three dimensions are involved in DV and weight (assuming that weight is proportional to volume), only two dimensions are obviously involved in BSA. However, a fractal geometry interpretation, related to an allometric scaling, suggests that the so-called 'body surface area' may stand for DV. (note)

Nature of the surface states at the single-layer graphene/Cu(111) and graphene/polycrystalline-Cu interfaces

NARCIS (Netherlands)

Pagliara, S.; Tognolini, S.; Bignardi, L.; Galimberti, G.; Achilli, S.; Trioni, M. I.; van Dorp, W. F.; Ocelik, V.; Rudolf, P.; Parmigiani, F.

2015-01-01

Single-layer graphene supported on a metal surface has shown remarkable properties relevant for novel electronic and optoelectronic devices. However, the nature of the electronic states derived from unoccupied surface states and quantum well states, lying in the real-space gap between the graphene

From Intensity Profile to Surface Normal: Photometric Stereo for Unknown Light Sources and Isotropic Reflectances.

Science.gov (United States)

Lu, Feng; Matsushita, Yasuyuki; Sato, Imari; Okabe, Takahiro; Sato, Yoichi

2015-10-01

We propose an uncalibrated photometric stereo method that works with general and unknown isotropic reflectances. Our method uses a pixel intensity profile, which is a sequence of radiance intensities recorded at a pixel under unknown varying directional illumination. We show that for general isotropic materials and uniformly distributed light directions, the geodesic distance between intensity profiles is linearly related to the angular difference of their corresponding surface normals, and that the intensity distribution of the intensity profile reveals reflectance properties. Based on these observations, we develop two methods for surface normal estimation; one for a general setting that uses only the recorded intensity profiles, the other for the case where a BRDF database is available while the exact BRDF of the target scene is still unknown. Quantitative and qualitative evaluations are conducted using both synthetic and real-world scenes, which show the state-of-the-art accuracy of smaller than 10 degree without using reference data and 5 degree with reference data for all 100 materials in MERL database.

Measure of horizontal and vertical displacement of the acromioclavicular joint after cutting ligament using X-ray and opto-electronic system.

Science.gov (United States)

Rochcongar, Goulven; Emily, Sébastien; Lebel, Benoit; Pineau, Vincent; Burdin, Gilles; Hulet, Christophe

2012-09-01

Surgical versus orthopedic treatments of acromioclavicular disjunction are still debated. The aim of this study was to measure horizontal and vertical acromion's displacement after cutting the ligament using standard X-ray and an opto-electronic system on cadaver. Ten cadaveric shoulders were studied. A sequential ligament's section was operated by arthroscopy. The sequence of cutting was chosen to fit with Rockwood's grade. The displacement of the acromion was measured on standard X-ray and with an opto-electronic system allowing measuring of the horizontal displacement. Statistical comparisons were performed using a paired Student's t test with significance set at p acromioclavicular ligament. The contact surface between the acromion and the clavicle decreases statistically after sectioning the acromioclavicular ligament and the coracoclavicular ligament with no effect of sectioning the delto-trapezius muscles. Those results are superposing with those dealing with the anterior translation. The measure concerning the acromioclavicular distance and the coracoclavicular distance are superposing with those of Rockwood. However, there is a significant horizontal translation after cutting the acromioclavicular ligament. Taking into account this displacement, it may be interesting to choose either surgical or orthopedic treatment. There is a correlation between anatomical damage and importance of instability. Horizontal instability is misevaluated in clinical practice.

Chemical vapor deposition growth of single-crystalline cesium lead halide microplatelets and heterostructures for optoelectronic applications

Institute of Scientific and Technical Information of China (English)

Yiliu Wang; Xun Guan; Dehui Li; Hung-Chieh Cheng; Xidong Duan; Zhaoyang Lin; Xiangfeng Duan

2017-01-01

Orgaruc-inorganic hybrid halide perovskites,such as CH3NH3PbI3,have emerged as an exciting class of materials for solar photovoltaic applications;however,they are currently plagued by insufficient environmental stability.To solve this issue,all-inorganic halide perovskites have been developed and shown to exhibit significantly improved stability.Here,we report a single-step chemical vapor deposition growth of cesium lead halide (CsPbX3) microcrystals.Optical microscopy studies show that the resulting perovskite crystals predominantly adopt a square-platelet morphology.Powder X-ray diffraction (PXRD) studies of the resulting crystals demonstrate a highly crystalline nature,with CsPbC13,CsPbBr3,and CsPbI3 showing tetragonal,monoclinic,and orthorhombic phases,respectively.Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies show that the resulting platelets exhibit well-faceted structures with lateral dimensions of the order of 10-50 μm,thickness around 1 μm,and ultra-smooth surface,suggesting the absence of obvious grain boundaries and the single-crystalline nature of the individual microplatelets.Photoluminescence (PL) images and spectroscopic studies show a uniform and intense emission consistent with the expected band edge transition.Additionally,PL images show brighter emission around the edge of the platelets,demonstrating a wave-guiding effect in high-quality crystals.With a well-defined geometry and ultra-smooth surface,the square platelet structure can function as a whispering gallery mode cavity with a quality factor up to 2,863 to support laser emission at room temperature.Finally,we demonstrate that such microplatelets can be readily grown on a variety of substrates,including silicon,graphene,and other two-dimensional materials such as molybdenum disulfide,which can readily allow the construction of heterostructure optoelectronic devices,including a graphene/perovskite/ graphene vertically-stacked photodetector with

Surface Traps in Colloidal Quantum Dot Solar Cells, their Mitigation and Impact on Manufacturability

KAUST Repository

Kirmani, Ahmad R.

2017-01-01

charge transport and threaten their otherwise wonderful optoelectronic properties. Surface traps have also, indirectly, impeded scalable and industry-compatible fabrication of these solar cells, as all of the reports, to date, have relied on spin

Evolution of the Contact Area with Normal Load for Rough Surfaces: from Atomic to Macroscopic Scales.

Science.gov (United States)

Huang, Shiping

2017-11-13

The evolution of the contact area with normal load for rough surfaces has great fundamental and practical importance, ranging from earthquake dynamics to machine wear. This work bridges the gap between the atomic scale and the macroscopic scale for normal contact behavior. The real contact area, which is formed by a large ensemble of discrete contacts (clusters), is proven to be much smaller than the apparent surface area. The distribution of the discrete contact clusters and the interaction between them are key to revealing the mechanism of the contacting solids. To this end, Green's function molecular dynamics (GFMD) is used to study both how the contact cluster evolves from the atomic scale to the macroscopic scale and the interaction between clusters. It is found that the interaction between clusters has a strong effect on their formation. The formation and distribution of the contact clusters is far more complicated than that predicted by the asperity model. Ignorance of the interaction between them leads to overestimating the contacting force. In real contact, contacting clusters are smaller and more discrete due to the interaction between the asperities. Understanding the exact nature of the contact area with the normal load is essential to the following research on friction.

An applicable approach for extracting human heart rate and oxygen saturation during physical movements using a multi-wavelength illumination optoelectronic sensor system

Science.gov (United States)

Alharbi, Samah; Hu, Sijung; Mulvaney, David; Blanos, Panagiotis

2018-02-01

The ability to gather physiological parameters such as heart rate (HR) and oxygen saturation (SpO2%) during physical movement allows to continuously monitor personal health status without disrupt their normal daily activities. Photoplethysmography (PPG) based pulse oximetry and similar principle devices are unable to extract the HR and SpO2% reliably during physical movement due to interference in the signals that arise from motion artefacts (MAs). In this research, a flexible reflectance multi-wavelength optoelectronic patch sensor (OEPS) has been developed to overcome the susceptibility of conventional pulse oximetry readings to MAs. The OEPS incorporates light embittered diodes as illumination sources with four different wavelengths, e.g. green, orange, red, and infrared unlike the conventional pulse oximetry devices that normally measure the skin absorption of only two wavelengths (red and infrared). The additional green and orange wavelengths were found to be distinguish to the absorption of deoxyhemoglobin (RHb) and oxyhemoglobin (HbO2). The reliability of extracting physiological parameters from the green and orange wavelengths is due to absorbed near to the surface of the skin, thereby shortening the optical path and so effectively reducing the influence of physical movements. To compensate of MAs, a three-axis accelerometer was used as a reference with help of adaptive filter to reduce MAs. The experiments were performed using 15 healthy subjects aged 20 to 30. The primary results show that there are no significant difference of heart rate and oxygen saturation measurements between commercial devices and OEPS Green (r=0.992), Orange(r=0.984), Red(r=0.952) and IR(r=0.97) and SpO2% (r = 0.982, p = 0.894).

Transparent Electrodes for Efficient Optoelectronics

KAUST Repository

Morales-Masis, Monica

2017-03-30

With the development of new generations of optoelectronic devices that combine high performance and novel functionalities (e.g., flexibility/bendability, adaptability, semi or full transparency), several classes of transparent electrodes have been developed in recent years. These range from optimized transparent conductive oxides (TCOs), which are historically the most commonly used transparent electrodes, to new electrodes made from nano- and 2D materials (e.g., metal nanowire networks and graphene), and to hybrid electrodes that integrate TCOs or dielectrics with nanowires, metal grids, or ultrathin metal films. Here, the most relevant transparent electrodes developed to date are introduced, their fundamental properties are described, and their materials are classified according to specific application requirements in high efficiency solar cells and flexible organic light-emitting diodes (OLEDs). This information serves as a guideline for selecting and developing appropriate transparent electrodes according to intended application requirements and functionality.

Optoelectronics of Molecules and Polymers

CERN Document Server

Moliton, André

2006-01-01

Optoelectronic devices are being developed at an extraordinary rate. Organic light emitting diodes, photovoltaic devices and electro-optical modulators are pivotal to the future of displays, photosensors and solar cells, and communication technologies. This book details the theories underlying the relevant mechanisms in organic materials and covers, at a basic level, how the organic components are made. The first part of this book introduces the fundamental theories used to detail ordered solids and localised energy levels. The methods used to determine energy levels in perfectly ordered molecular and macromolecular systems are discussed, making sure that the effects of quasi-particles are not missed. The function of excitons and their transfer between two molecules are studied, and the problems associated with interfaces and charge injection into resistive media are presented. The second part details technological aspects such as the fabrication of devices based on organic materials by dry etching. The princ...

Transparent Electrodes for Efficient Optoelectronics

KAUST Repository

Morales-Masis, Monica; De Wolf, Stefaan; Woods-Robinson, Rachel; Ager, Joel W.; Ballif, Christophe

2017-01-01

With the development of new generations of optoelectronic devices that combine high performance and novel functionalities (e.g., flexibility/bendability, adaptability, semi or full transparency), several classes of transparent electrodes have been developed in recent years. These range from optimized transparent conductive oxides (TCOs), which are historically the most commonly used transparent electrodes, to new electrodes made from nano- and 2D materials (e.g., metal nanowire networks and graphene), and to hybrid electrodes that integrate TCOs or dielectrics with nanowires, metal grids, or ultrathin metal films. Here, the most relevant transparent electrodes developed to date are introduced, their fundamental properties are described, and their materials are classified according to specific application requirements in high efficiency solar cells and flexible organic light-emitting diodes (OLEDs). This information serves as a guideline for selecting and developing appropriate transparent electrodes according to intended application requirements and functionality.

Near infrared group IV optoelectronics and novel pre-cursors for CVD epitaxy

Science.gov (United States)

Hazbun, Ramsey Michael

Near infrared and mid infrared optoelectronic devices have become increasingly important for the telecommunications, security, and medical imaging industries. The addition of nitrogen to III-V alloys has been widely studied as a method of modifying the band gap for mid infrared (IR) applications. In xGa1-xSb1-y Ny/InAs strained-layer superlattices with type-II (staggered) energy offsets on GaSb substrates, were modeled using eight-band k˙p simulations to analyze the superlattice miniband energies. Three different zero-stress strain balance conditions are reported: fixed superlattice period thickness, fixed InAs well thickness, and fixed InxGa1-xSb 1-yNy barrier thickness. Optoelectronics have traditionally been the realm of III-V semiconductors due to their direct band gap, while integrated circuit chips have been the realm of Group IV semiconductors such as silicon because of its relative abundance and ease of use. Recently the alloying of Sn with Ge and Si has been shown to allow direct band-gap light emission. This presents the exciting prospect of integrating optoelectronics into current Group IV chip fabrication facilities. However, new approaches for low temperature growth are needed to realize these new SiGeSn alloys. Silicon-germanium epitaxy via ultra-high vacuum chemical vapor deposition has the advantage of allowing low process temperatures. Deposition processes are sensitive to substrate surface preparation and the time delay between oxide removal and epitaxial growth. A new monitoring process utilizing doped substrates and defect decoration etching is demonstrated to have controllable and unique sensitivity to interfacial contaminants. Doped substrates were prepared and subjected to various loading conditions prior to the growth of typical Si/SiGe bilayers. The defect densities were correlated to the concentration of interfacial oxygen suggesting this monitoring process may be an effective complement to monitoring via secondary ion mass spectrometry

Wonder of nanotechnology quantum optoelectronic devices and applications

CERN Document Server

Razeghi, Manijeh; von Klitzing, Klaus

2013-01-01

When you look closely, Nature is nanotechnology at its finest. From a single cell, a factory all by itself, to complex systems, such as the nervous system or the human eye, each is composed of specialized nanostructures that exist to perform a specific function. This same beauty can be mirrored when we interact with the tiny physical world that is the realm of quantum mechanics.The Wonder of Nanotechnology: Quantum Optoelectronic Devices and Applications, edited by Manijeh Razeghi, Leo Esaki, and Klaus von Klitzing focuses on the application of nanotechnology to modern semiconductor optoelectr

Integrated Automatic Test System for Airborne Optoelectronic Pods

International Nuclear Information System (INIS)

Zhang, Z M; Ding, M J; Wang, L

2006-01-01

Based on the introduction of the construction and basic principle of the airborne optoelectronic pod, in accordance with the performance standards of the pod, the total solution scheme of the automatic test system used for testing the combination property is proposed in this paper. The main structure, hardware and software design of the system based on the virtual instruments technology are also discussed in detail. The result of the true run proves the practicality, efficiency, high accuracy and other characteristics of the computer aided testing system based on virtual instruments

Graphene and Two-Dimensional Materials for Optoelectronic Applications

Directory of Open Access Journals (Sweden)

Andreas Bablich

2016-03-01

Full Text Available This article reviews optoelectronic devices based on graphene and related two-dimensional (2D materials. The review includes basic considerations of process technology, including demonstrations of 2D heterostructure growth, and comments on the scalability and manufacturability of the growth methods. We then assess the potential of graphene-based transparent conducting electrodes. A major part of the review describes photodetectors based on lateral graphene p-n junctions and Schottky diodes. Finally, the progress in vertical devices made from 2D/3D heterojunctions, as well as all-2D heterostructures is discussed.

Graphene surface plasmon polaritons with opposite in-plane electron oscillations along its two surfaces

International Nuclear Information System (INIS)

Liang, Huawei; Ruan, Shuangchen; Zhang, Min; Su, Hong; Li, Irene Ling

2015-01-01

We predict the existence of a surface plasmon polariton (SPP) mode that can be guided by a graphene monolayer, regardless of the sign of the imaginary part of its conductivity. In this mode, in-plane electron oscillations along two surfaces of graphene are of opposite directions, which is very different from conventional SPPs on graphene. Significantly, coating graphene with dielectric films yields a way to guide the SPPs with both sub-wavelength mode widths and ultra-long propagation distances. In particular, the mode characteristics are very sensitive to the chemical potential of graphene, so the graphene-based waveguide can find applications in many optoelectronic devices

Graphene surface plasmon polaritons with opposite in-plane electron oscillations along its two surfaces

Energy Technology Data Exchange (ETDEWEB)

Liang, Huawei; Ruan, Shuangchen, E-mail: scruan@szu.edu.cn; Zhang, Min; Su, Hong; Li, Irene Ling [Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060 (China)

2015-08-31

We predict the existence of a surface plasmon polariton (SPP) mode that can be guided by a graphene monolayer, regardless of the sign of the imaginary part of its conductivity. In this mode, in-plane electron oscillations along two surfaces of graphene are of opposite directions, which is very different from conventional SPPs on graphene. Significantly, coating graphene with dielectric films yields a way to guide the SPPs with both sub-wavelength mode widths and ultra-long propagation distances. In particular, the mode characteristics are very sensitive to the chemical potential of graphene, so the graphene-based waveguide can find applications in many optoelectronic devices.

Trajectories of cortical surface area and cortical volume maturation in normal brain development

Directory of Open Access Journals (Sweden)

Simon Ducharme

2015-12-01

Full Text Available This is a report of developmental trajectories of cortical surface area and cortical volume in the NIH MRI Study of Normal Brain Development. The quality-controlled sample included 384 individual typically-developing subjects with repeated scanning (1–3 per subject, total scans n=753 from 4.9 to 22.3 years of age. The best-fit model (cubic, quadratic, or first-order linear was identified at each vertex using mixed-effects models, with statistical correction for multiple comparisons using random field theory. Analyses were performed with and without controlling for total brain volume. These data are provided for reference and comparison with other databases. Further discussion and interpretation on cortical developmental trajectories can be found in the associated Ducharme et al.׳s article “Trajectories of cortical thickness maturation in normal brain development – the importance of quality control procedures” (Ducharme et al., 2015 [1].

Morphological evolution of dissolving feldspar particles with anisotropic surface kinetics and implications for dissolution rate normalization and grain size dependence: A kinetic modeling study

Science.gov (United States)

Zhang, Li; Lüttge, Andreas

2009-11-01

With previous two-dimensional (2D) simulations based on surface-specific feldspar dissolution succeeding in relating the macroscopic feldspar kinetics to the molecular-scale surface reactions of Si and Al atoms ( Zhang and Lüttge, 2008, 2009), we extended our modeling effort to three-dimensional (3D) feldspar particle dissolution simulations. Bearing on the same theoretical basis, the 3D feldspar particle dissolution simulations have verified the anisotropic surface kinetics observed in the 2D surface-specific simulations. The combined effect of saturation state, pH, and temperature on the surface kinetics anisotropy has been subsequently evaluated, found offering diverse options for morphological evolution of dissolving feldspar nanoparticles with varying grain sizes and starting shapes. Among the three primary faces on the simulated feldspar surface, the (1 0 0) face has the biggest dissolution rate across an extensively wide saturation state range and thus acquires a higher percentage of the surface area upon dissolution. The slowest dissolution occurs to either (0 0 1) or (0 1 0) faces depending on the bond energies of Si-(O)-Si ( ΦSi-O-Si/ kT) and Al-(O)-Si ( ΦAl-O-Si/ kT). When the ratio of ΦSi-O-Si/ kT to ΦAl-O-Si/ kT changes from 6:3 to 7:5, the dissolution rates of three primary faces change from the trend of (1 0 0) > (0 1 0) > (0 0 1) to the trend of (1 0 0) > (0 0 1) > (0 1 0). The rate difference between faces becomes more distinct and accordingly edge rounding becomes more significant. Feldspar nanoparticles also experience an increasing degree of edge rounding from far-from-equilibrium to close-to-equilibrium. Furthermore, we assessed the connection between the continuous morphological modification and the variation in the bulk dissolution rate during the dissolution of a single feldspar particle. Different normalization treatments equivalent to the commonly used mass, cube assumption, sphere assumption, geometric surface area, and reactive

Mild Conditions for Deuteration of Primary and Secondary Arylamines for the Synthesis of Deuterated Optoelectronic Organic Molecules

Directory of Open Access Journals (Sweden)

Anwen M. Krause-Heuer

2014-11-01

Full Text Available Deuterated arylamines demonstrate great potential for use in optoelectronic devices, but their widespread utility requires a method for large-scale synthesis. The incorporation of these deuterated materials into optoelectronic devices also provides the opportunity for studies of the functioning device using neutron reflectometry based on the difference in the scattering length density between protonated and deuterated compounds. Here we report mild deuteration conditions utilising standard laboratory glassware for the deuteration of: diphenylamine, N-phenylnaphthylamine, N-phenyl-o-phenylenediamine and 1-naphthylamine (via H/D exchange in D2O at 80 °C, catalysed by Pt/C and Pd/C. These conditions were not successful in the deuteration of triphenylamine or N,N-dimethylaniline, suggesting that these mild conditions are not suitable for the deuteration of tertiary arylamines, but are likely to be applicable for the deuteration of other primary and secondary arylamines. The deuterated arylamines can then be used for synthesis of larger organic molecules or polymers with optoelectronic applications.

Accuracy of dielectric-dependent hybrid functionals in the prediction of optoelectronic properties of metal oxide semiconductors: a comprehensive comparison with many-body GW and experiments

Science.gov (United States)

Gerosa, M.; E Bottani, C.; Di Valentin, C.; Onida, G.; Pacchioni, G.

2018-01-01

Understanding the electronic structure of metal oxide semiconductors is crucial to their numerous technological applications, such as photoelectrochemical water splitting and solar cells. The needed experimental and theoretical knowledge goes beyond that of pristine bulk crystals, and must include the effects of surfaces and interfaces, as well as those due to the presence of intrinsic defects (e.g. oxygen vacancies), or dopants for band engineering. In this review, we present an account of the recent efforts in predicting and understanding the optoelectronic properties of oxides using ab initio theoretical methods. In particular, we discuss the performance of recently developed dielectric-dependent hybrid functionals, providing a comparison against the results of many-body GW calculations, including G 0 W 0 as well as more refined approaches, such as quasiparticle self-consistent GW. We summarize results in the recent literature for the band gap, the band level alignment at surfaces, and optical transition energies in defective oxides, including wide gap oxide semiconductors and transition metal oxides. Correlated transition metal oxides are also discussed. For each method, we describe successes and drawbacks, emphasizing the challenges faced by the development of improved theoretical approaches. The theoretical section is preceded by a critical overview of the main experimental techniques needed to characterize the optoelectronic properties of semiconductors, including absorption and reflection spectroscopy, photoemission, and scanning tunneling spectroscopy (STS).

Proceedings of the thirty fifth international conference on contemporary trends in optics and optoelectronics: conference digest - extended abstracts

International Nuclear Information System (INIS)

2011-01-01

Optics and optoelectronics are indispensable in all spheres of human activity, ranging from day to day needs to advanced scientific and technological pursuits and their applications for the benefit of the society. This conference covers the following topics: adaptive optics, biomedical optics and imaging, classical and quantum optics, fibre optics, optics for space applications, optical metrology and NDT, optical information processing, optical and optoelectronic materials. Papers relevant to INIS are indexed separately

All-optoelectronic continuous wave THz imaging for biomedical applications

International Nuclear Information System (INIS)

Siebert, Karsten J; Loeffler, Torsten; Quast, Holger; Thomson, Mark; Bauer, Tobias; Leonhardt, Rainer; Czasch, Stephanie; Roskos, Hartmut G

2002-01-01

We present an all-optoelectronic THz imaging system for ex vivo biomedical applications based on photomixing of two continuous-wave laser beams using photoconductive antennas. The application of hyperboloidal lenses is discussed. They allow for f-numbers less than 1/2 permitting better focusing and higher spatial resolution compared to off-axis paraboloidal mirrors whose f-numbers for practical reasons must be larger than 1/2. For a specific histological sample, an analysis of image noise is discussed

Comprehensive study of the influence of different environments on degradation processes in F8BT: Correlating optoelectronic properties with Raman measurements

International Nuclear Information System (INIS)

Linde, Sivan; Shikler, Rafi

2013-01-01

There is a growing interest in conjugated polymers from both industrial and academic points of views. The reasons are their tunable optoelectronic properties, ease of production, and excellent mechanical properties. However, the ease with which their optoelectronic properties are tunable make devices based on them prone to fast degradation and therefore, short life time. The issue of degradation of organic based optoelectronic devices is the topic of many ongoing researches. However, much less attention is given to degradation processes of the individual components of the devices and their dependence on the environmental conditions. In this work, we report on the degradation of a film of a polyfluorene block copolymer F8BT that is used in a variety of optoelectronic devices under different environments: Sun exposure, heating, and UV exposure in inert and ambient conditions. Degradation was observed in most of the optoelectronic properties of the film. Topographic measurements did not show observable changes of the film morphology following degradation. However, Raman spectroscopy measurements show changes that indicate degradation in one of the building blocks of the copolymer that is associated with electron's conduction. The absolute value of the correlation coefficient between the decrease in the Raman signal and the decrease in the optoelectronic properties is larger than 0.95 under sun exposure it is larger than 0.8 under all other ambient exposures and smaller than 0.65 under inert conditions. These results support the assumption that Oxygen, not necessarily through photo-oxidation, and also water play an important role in the degradation process and indicate the part of the polymer that is most susceptible to degradation

Precision Controlled Carbon Materials for Next-Generation Optoelectronic and Photonic Devices

Science.gov (United States)

2018-01-08

engineer next-generation carbon-based optoelectronic and photonic devices with superior performance and capabilities. These devices include carbon...electronics; (4) nanostructured graphene plasmonics; and (5) polymer-nanotube conjugate chemistry . (1) Semiconducting carbon nanotube-based...applications (In Preparation, 2018). (5) Polymer-nanotube conjugate chemistry Conjugated polymers can be exploited as agents for selectively wrapping and

Analysis on the dynamic error for optoelectronic scanning coordinate measurement network

Science.gov (United States)

Shi, Shendong; Yang, Linghui; Lin, Jiarui; Guo, Siyang; Ren, Yongjie

2018-01-01

Large-scale dynamic three-dimension coordinate measurement technique is eagerly demanded in equipment manufacturing. Noted for advantages of high accuracy, scale expandability and multitask parallel measurement, optoelectronic scanning measurement network has got close attention. It is widely used in large components jointing, spacecraft rendezvous and docking simulation, digital shipbuilding and automated guided vehicle navigation. At present, most research about optoelectronic scanning measurement network is focused on static measurement capacity and research about dynamic accuracy is insufficient. Limited by the measurement principle, the dynamic error is non-negligible and restricts the application. The workshop measurement and positioning system is a representative which can realize dynamic measurement function in theory. In this paper we conduct deep research on dynamic error resources and divide them two parts: phase error and synchronization error. Dynamic error model is constructed. Based on the theory above, simulation about dynamic error is carried out. Dynamic error is quantized and the rule of volatility and periodicity has been found. Dynamic error characteristics are shown in detail. The research result lays foundation for further accuracy improvement.

A low noise preamplifier with optoelectronic overload protection for radioactivity measurement

International Nuclear Information System (INIS)

Sephton, J.P.; Williams, J.M.; Johansson, L.C.; Philips, H.C.

2012-01-01

Pulses from detectors used for radioactivity measurement can vary in size by several orders of magnitude. Large pulses will lead to saturation at the preamplifier output and extension of the pulse length. As a consequence, the dead time of the system increases and pulses may be lost. Electronic design techniques employed to protect against overloading tend to increase the amplifier noise level. However, an optoelectronic method of overload protection has been devised which has only a negligible effect on noise. An infrared light emitting diode interfaced to the output of the preamplifier is linked by fibre optic cable to an ultra-low leakage photodiode at the input. The conduction of the photodiode increases with the amplitude of the preamplifier output signal. Excess current is thereby prevented from entering the preamplifier and causing saturation. The preamplifier has been tested on 4π beta–gamma and gas counting systems and found to give good protection against overloading. - Highlights: ► A preamplifier for radioactivity measurements has been developed. ► Low noise. ► Current sensitive. ► Optoelectronic overload protection.

Potassium ions in SiO2: electrets for silicon surface passivation

Science.gov (United States)

Bonilla, Ruy S.; Wilshaw, Peter R.

2018-01-01

This manuscript reports an experimental and theoretical study of the transport of potassium ions in thin silicon dioxide films. While alkali contamination was largely researched in the context of MOSFET instability, recent reports indicate that potassium ions can be embedded into oxide films to produce dielectric materials with permanent electric charge, also known as electrets. These electrets are integral to a number of applications, including the passivation of silicon surfaces for optoelectronic devices. In this work, electric field assisted migration of ions is used to rapidly drive K+ into SiO2 and produce effective passivation of silicon surfaces. Charge concentrations of up to ~5  ×  1012 e cm-2 have been achieved. This charge was seen to be stable for over 1500 d, with decay time constants as high as 17 000 d, producing an effectively passivated oxide-silicon interface with SRV  industrial manufacture of silicon optoelectronic devices.

Electroactive and Optoelectronically Active Graphene Nanofilms

DEFF Research Database (Denmark)

Chi, Qijin

As an atomic-scale-thick two-dimensional material, graphene has emerged as one of the most miracle materials and has generated intensive interest in physics, chemistry and even biology in the last decade [1, 2]. Nanoscale engineering and functionalization of graphene is a crucial step for many...... applications ranging from catalysis, electronic devices, sensors to advanced energy conversion and storage [3]. This talk highlights our recent studies on electroactive and optoelectronically active graphene ultrathin films for chemical sensors and energy technology. The presentation includes a general theme...... for functionalization of graphene nanosheets, followed by showing several case studies. Our systems cover redox-active nanoparticles, electroactive supramolecular ensembles and redox enzymes which are integrated with graphene nanosheets as building blocks for the construction of functional thin films or graphene papers....

On the Origin of Surface Traps in Colloidal II–VI Semiconductor Nanocrystals

NARCIS (Netherlands)

Houtepen, Arjan J.; Hens, Zeger; Owen, Jonathan S.; Infante, Ivan

2017-01-01

One of the greatest challenges in the field of semiconductor nanomaterials is to make trap-free nanocrystalline structures to attain a remarkable improvement of their optoelectronic performances. In semiconductor nanomaterials, a very high number of atoms is located on the surface and these atoms

Optoelectronical properties of InGaN quantum well light emitting diodes on semipolar GaN

Energy Technology Data Exchange (ETDEWEB)

Rass, Jens; Stascheit, Marcus; Ploch, Simon; Wernicke, Tim; Vogt, Patrick; Kneissl, Michael [Technische Universitaet Berlin, Institute of Solid State Physics, Secretariat EW6-1, Hardenbergstrasse 36, 10623 Berlin (Germany)

2011-07-01

The performance of GaN-based light emitting diodes (LEDs) is strongly affected by polarization fields along the c-axis of the crystal. Due to the resulting quantum-confined Stark effect the radiative transition rate is reduced and the emission wavelength is blue-shifted when carriers are injected. By growing the structures on semipolar or nonpolar planes the polarization fields can be significantly reduced or even eliminated. In this work, InGaN single quantum well LEDs have been grown by metal-organic vapor phase epitaxy on different semipolar surfaces such as the (10 anti 11) and (20 anti 21) plane. The optoelectronic properties such as the light output power, the emission wavelength and its shift with injection current as well as the operating voltage have been studied. By employing capacitance-voltage- and current-voltage measurements, the size of the depletion region, the build-in potential, the saturation current and the doping concentrations have been determined. LEDs with emission wavelengths ranging from the violet to the blue and green region are presented and their performance characteristics are compared to LEDs grown on the polar c-plane surface.

Comparative analysis of the surface exposed proteome of two canine osteosarcoma cell lines and normal canine osteoblasts.

Science.gov (United States)

Milovancev, Milan; Hilgart-Martiszus, Ian; McNamara, Michael J; Goodall, Cheri P; Seguin, Bernard; Bracha, Shay; Wickramasekara, Samanthi I

2013-06-13

Osteosarcoma (OSA) is the most common primary bone tumor of dogs and carries a poor prognosis despite aggressive treatment. An improved understanding of the biology of OSA is critically needed to allow for development of novel diagnostic, prognostic, and therapeutic tools. The surface-exposed proteome (SEP) of a cancerous cell includes a multifarious array of proteins critical to cellular processes such as proliferation, migration, adhesion, and inter-cellular communication. The specific aim of this study was to define a SEP profile of two validated canine OSA cell lines and a normal canine osteoblast cell line utilizing a biotinylation/streptavidin system to selectively label, purify, and identify surface-exposed proteins by mass spectrometry (MS) analysis. Additionally, we sought to validate a subset of our MS-based observations via quantitative real-time PCR, Western blot and semi-quantitative immunocytochemistry. Our hypothesis was that MS would detect differences in the SEP composition between the OSA and the normal osteoblast cells. Shotgun MS identified 133 putative surface proteins when output from all samples were combined, with good consistency between biological replicates. Eleven of the MS-detected proteins underwent analysis of gene expression by PCR, all of which were actively transcribed, but varied in expression level. Western blot of whole cell lysates from all three cell lines was effective for Thrombospondin-1, CYR61 and CD44, and indicated that all three proteins were present in each cell line. Semi-quantitative immunofluorescence indicated that CD44 was expressed at much higher levels on the surface of the OSA than the normal osteoblast cell lines. The results of the present study identified numerous differences, and similarities, in the SEP of canine OSA cell lines and normal canine osteoblasts. The PCR, Western blot, and immunocytochemistry results, for the subset of proteins evaluated, were generally supportive of the mass spectrometry data

Coupling of morphology to surface transport in ion-beam-irradiated surfaces: normal incidence and rotating targets

International Nuclear Information System (INIS)

Munoz-Garcia, Javier; Cuerno, Rodolfo; Castro, Mario

2009-01-01

Continuum models have proved their applicability to describe nanopatterns produced by ion-beam sputtering of amorphous or amorphizable targets at low and medium energies. Here we pursue the recently introduced 'hydrodynamic approach' in the cases of bombardment at normal incidence, or of oblique incidence onto rotating targets, known to lead to self-organized arrangements of nanodots. Our approach stresses the dynamical roles of material (defect) transport at the target surface and of local redeposition. By applying results previously derived for arbitrary angles of incidence, we derive effective evolution equations for these geometries of incidence, which are then numerically studied. Moreover, we show that within our model these equations are identical (albeit with different coefficients) in both cases, provided surface tension is isotropic in the target. We thus account for the common dynamics for both types of incidence conditions, namely formation of dots with short-range order and long-wavelength disorder, and an intermediate coarsening of dot features that improves the local order of the patterns. We provide for the first time approximate analytical predictions for the dependence of stationary dot features (amplitude and wavelength) on phenomenological parameters, that improve upon previous linear estimates. Finally, our theoretical results are discussed in terms of experimental data.

SPEKTROP DPU: optoelectronic platform for fast multispectral imaging

Science.gov (United States)

Graczyk, Rafal; Sitek, Piotr; Stolarski, Marcin

2010-09-01

In recent years it easy to spot and increasing need of high-quality Earth imaging in airborne and space applications. This is due fact that government and local authorities urge for up to date topological data for administrative purposes. On the other hand, interest in environmental sciences, push for ecological approach, efficient agriculture and forests management are also heavily supported by Earth images in various resolutions and spectral ranges. "SPEKTROP DPU: Opto-electronic platform for fast multi-spectral imaging" paper describes architectural datails of data processing unit, part of universal and modular platform that provides high quality imaging functionality in aerospace applications.

Design of optoelectronic system for optical diffusion tomography

Directory of Open Access Journals (Sweden)

Erakhtin Igor

2017-01-01

Full Text Available This article explores issues connected with the circuit design of a device for optical diffusion tomography, which we are currently designing. We plan to use the device in experimental studies for the development of a faster method of brain hematoma detection. We reviewed currently existing methods for emergency diagnosis of hematomas, primarily the Infrascanner model 2000, for which we identified weaknesses, and outlined suggestions for improvements. This article describes the method of scanning tissues based on a triangulated arrangement of sources and receivers of optical radiation, and it discusses the optoelectronic system that implements that principle.

How phase composition influences optoelectronic and photocatalytic properties of TiO2

NARCIS (Netherlands)

Carneiro, J.T.; Carneiro, Joana T.; Savenije, Tom J.; Moulijn, Jacob A.; Mul, Guido

2011-01-01

In the present study the ratio of rutile and anatase phases in sol−gel-synthe-sized TiO2 was varied by calcination at temperatures ranging from 500 to 900 °C. Changes in opto-electronic properties were analyzed by time-resolved microwave conductance measurements (TRMC) and evaluated by comparison of

Laser applications in the electronics and optoelectronics industry in Japan

Science.gov (United States)

Washio, Kunihiko

1999-07-01

This paper explains current status and technological trends in laser materials processing applications in electronics and optoelectronics industry in Japan. Various laser equipment based on solid state lasers or gas lasers such as excimer lasers or CO2 lasers has been developed and applied in manufacturing electronic and optoelectronic devices to meet the strong demands for advanced device manufacturing technologies for high-performance, lightweight, low power-consumption portable digital electronic appliances, cellular mobile phones, personal computers, etc. Representative applications of solid-state lasers are, opaque and clear defects repairing of photomasks for LSIs and LCDs, trimming of thick-film chip resistors and low resistance metal resistors, laser cutting and drilling of thin films for high-pin count semiconductor CSP packages, laser patterning of thin-film amorphous silicon solar cells, and laser welding of electronic components such as hard-disk head suspensions, optical modules, miniature relays and lithium ion batteries. Compact and highly efficient diode- pumped and Q-switched solid-state lasers in second or third harmonic operation mode are now being increasingly incorporated in various laser equipment for fine material processing. Representative applications of excimer lasers are, sub-quarter micron design-rule LSI lithography and low- temperature annealing of poly-silicon TFT LCD.

Adaptive integral backstepping sliding mode control for opto-electronic tracking system based on modified LuGre friction model

Science.gov (United States)

Yue, Fengfa; Li, Xingfei; Chen, Cheng; Tan, Wenbin

2017-12-01

In order to improve the control accuracy and stability of opto-electronic tracking system fixed on reef or airport under friction and external disturbance conditions, adaptive integral backstepping sliding mode control approach with friction compensation is developed to achieve accurate and stable tracking for fast moving target. The nonlinear observer and slide mode controller based on modified LuGre model with friction compensation can effectively reduce the influence of nonlinear friction and disturbance of this servo system. The stability of the closed-loop system is guaranteed by Lyapunov theory. The steady-state error of the system is eliminated by integral action. The adaptive integral backstepping sliding mode controller and its performance are validated by a nonlinear modified LuGre dynamic model of the opto-electronic tracking system in simulation and practical experiments. The experiment results demonstrate that the proposed controller can effectively realise the accuracy and stability control of opto-electronic tracking system.

Modelling and characterisation of surface plasmon based sensors for the detection of E. coli

Czech Academy of Sciences Publication Activity Database

Rajarajan, M.; Dar, T.; Themistos, Ch.; Rahman, A.; Grattan, K.; Homola, Jiří

2009-01-01

Roč. 56, č. 4 (2009), s. 564-571 ISSN 0950-0340 Institutional research plan: CEZ:AV0Z20670512 Keywords : SPR sensor * long-range surface plasmon * bacterium Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.942, year: 2009

Temperature-Induced Lattice Relaxation of Perovskite Crystal Enhances Optoelectronic Properties and Solar Cell Performance

KAUST Repository

Banavoth, Murali; Yengel, Emre; Peng, Wei; Chen, Zhijie; Alias, Mohd Sharizal; Alarousu, Erkki; Ooi, Boon S.; Burlakov, Victor; Goriely, Alain; Eddaoudi, Mohamed; Bakr, Osman; Mohammed, Omar F.

2016-01-01

Hybrid organic-inorganic perovskite crystals have recently become one of the most important classes of photoactive materials in the solar cell and optoelectronic communities. Albeit improvements have focused on state-of-the-art technology including

Surface tension driven aggregation of organic nanowires via lab in a droplet.

Science.gov (United States)

Gu, Jianmin; Yin, Baipeng; Fu, Shaoyan; Feng, Man; Zhang, Ziming; Dong, Haiyun; Gao, Faming; Zhao, Yong Sheng

2018-06-05

Directing the architecture of complex organic nanostructures is desirable and still remains a challenge in areas of materials science due to their structure-dependent collective optoelectronic properties. Herein, we demonstrate a simple and versatile solution strategy that allows surface tension to drive low-dimensional nanostructures to aggregate into complex structures via a lab in a droplet technique. By selecting a suitable combination of a solvent and an anti-solvent with controllable surface tension difference, the droplets can be automatically cracked into micro-droplets, which provides an aggregation force directed toward the centre of the droplet to drive the low-dimensional building blocks to form the special aggregations during the self-assembly process. This synthetic strategy has been shown to be universal for organic materials, which is beneficial for further optimizing the optoelectronic properties. These results contribute to gaining an insightful understanding on the detailed growth mechanism of complex organic nanostructures and greatly promoting the development of organic nanophotonics.

Novel concept of multi-channel fiber optic surface plasmon resonance sensor

Czech Academy of Sciences Publication Activity Database

Špačková, Barbora; Piliarik, Marek; Kvasnička, Pavel; Rajarajan, M.; Homola, Jiří

2009-01-01

Roč. 139, č. 1 (2009), s. 199-203 ISSN 0925-4005 R&D Projects: GA AV ČR KAN200670701 Institutional research plan: CEZ:AV0Z20670512 Keywords : . Surface plasmon resonance * Fiber optic * Bragg grating * Biosensor Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.083, year: 2009

Nanoscale Surface Photovoltage Mapping of 2D Materials and Heterostructures by Illuminated Kelvin Probe Force Microscopy

KAUST Repository

Shearer, Melinda J.

2018-02-01

Nanomaterials are interesting for a variety of applications, such as optoelectronics and photovoltaics. However, they often have spatial heterogeneity, i.e. composition change or physical change in the topography or structure, which can lead to varying properties that would influence their applications. New techniques must be developed to understand and correlate spatial heterogeneity with changes in electronic properties. Here we highlight the technique of surface photovoltage-Kelvin probe force microscopy (SPV-KFM), which is a modified version of non-contact atomic force microscopy capable of imaging not only the topography and surface potential, but also the surface photovoltage on the nanoscale. We demonstrate its utility in probing monolayer WSe2-MoS2 lateral heterostructures, which form an ultrathin p-n junction promising for photovoltaic and optoelectronic applications. We show surface photovoltage maps highlighting the different photoresponse of the two material regions as a result of the effective charge separation across this junction. Additionally, we study the variations between different heterostructure flakes and emphasize the importance of controlling the synthesis and transfer of these materials to obtain consistent properties and measurements.

Nanoscale Surface Photovoltage Mapping of 2D Materials and Heterostructures by Illuminated Kelvin Probe Force Microscopy

KAUST Repository

Shearer, Melinda J.; Li, Ming-yang; Li, Lain-Jong; Jin, Song; Hamers, Robert J

2018-01-01

Nanomaterials are interesting for a variety of applications, such as optoelectronics and photovoltaics. However, they often have spatial heterogeneity, i.e. composition change or physical change in the topography or structure, which can lead to varying properties that would influence their applications. New techniques must be developed to understand and correlate spatial heterogeneity with changes in electronic properties. Here we highlight the technique of surface photovoltage-Kelvin probe force microscopy (SPV-KFM), which is a modified version of non-contact atomic force microscopy capable of imaging not only the topography and surface potential, but also the surface photovoltage on the nanoscale. We demonstrate its utility in probing monolayer WSe2-MoS2 lateral heterostructures, which form an ultrathin p-n junction promising for photovoltaic and optoelectronic applications. We show surface photovoltage maps highlighting the different photoresponse of the two material regions as a result of the effective charge separation across this junction. Additionally, we study the variations between different heterostructure flakes and emphasize the importance of controlling the synthesis and transfer of these materials to obtain consistent properties and measurements.

Tungsten oxides as interfacial layers for improved performance in hybrid optoelectronic devices

International Nuclear Information System (INIS)

Vasilopoulou, M.; Palilis, L.C.; Georgiadou, D.G.; Argitis, P.; Kennou, S.; Kostis, I.; Papadimitropoulos, G.; Stathopoulos, N.A.; Iliadis, A.A.; Konofaos, N.; Davazoglou, D.; Sygellou, L.

2011-01-01

Tungsten oxide (WO 3 ) films with thicknesses ranging from 30 to 100 nm were grown by Hot Filament Vapor Deposition (HFVD). Films were studied by X-Ray Photoemission Spectroscopy (XPS) and were found to be stoichiometric. The surface morphology of the films was characterized by Atomic Force Microscopy (AFM). Samples had a granular form with grains in the order of 100 nm. The surface roughness was found to increase with film thickness. HFVD WO 3 films were used as conducting interfacial layers in advanced hybrid organic-inorganic optoelectronic devices. Hybrid-Organic Light Emitting Diodes (Hy-OLEDs) and Organic Photovoltaics (Hy-OPVs) were fabricated with these films as anode and/or as cathode interfacial conducting layers. The Hy-OLEDs showed significantly higher current density and a lower turn-on voltage when a thin WO 3 layer was inserted at the anode/polymer interface, while when inserted at the cathode/polymer interface the device performance was found to deteriorate. The improvement was attributed to a more efficient hole injection and transport from the Fermi level of the anode to the Highest Occupied Molecular Orbital (HOMO) of a yellow emitting copolymer (YEP). On the other hand, the insertion of a thin WO 3 layer at the cathode/polymer interface of Hy-OPV devices based on a polythiophene-fullerene bulk-heterojunction blend photoactive layer resulted in an increase of the produced photogenerated current, more likely due to improved electron extraction at the Al cathode.

Direct Photolithography on Molecular Crystals for High Performance Organic Optoelectronic Devices.

Science.gov (United States)

Yao, Yifan; Zhang, Lei; Leydecker, Tim; Samorì, Paolo

2018-05-23

Organic crystals are generated via the bottom-up self-assembly of molecular building blocks which are held together through weak noncovalent interactions. Although they revealed extraordinary charge transport characteristics, their labile nature represents a major drawback toward their integration in optoelectronic devices when the use of sophisticated patterning techniques is required. Here we have devised a radically new method to enable the use of photolithography directly on molecular crystals, with a spatial resolution below 300 nm, thereby allowing the precise wiring up of multiple crystals on demand. Two archetypal organic crystals, i.e., p-type 2,7-diphenyl[1]benzothieno[3,2- b][1]benzothiophene (Dph-BTBT) nanoflakes and n-type N, N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) nanowires, have been exploited as active materials to realize high-performance top-contact organic field-effect transistors (OFETs), inverter and p-n heterojunction photovoltaic devices supported on plastic substrate. The compatibility of our direct photolithography technique with organic molecular crystals is key for exploiting the full potential of organic electronics for sophisticated large-area devices and logic circuitries, thus paving the way toward novel applications in plastic (opto)electronics.

Biomimetic hairy surfaces as superhydrophobic highly transmissive films for optical applications (Conference Presentation)

Science.gov (United States)

Vuellers, Felix; Gomard, Guillaume; Preinfalk, Jan B.; Klampaftis, Efthymios; Worgull, Matthias; Richards, Bryce S.; Hölscher, Hendrik; Kavalenka, Maryna N.

2017-02-01

Combining high optical transmission, water-repellency and self-cleaning is of great interest for optoelectronic devices operating in outdoor conditions, such as photovoltaics where shading can significantly reduce the power output. The surface of water plant Pistia stratiotes combines these functionalities through a dense layer of transparent microhairs. It renders the surface superhydrophobic without affecting absorption of sunlight necessary for photosynthesis. Inspired by this surface, we fabricated a superhydrophobic flexible thin nanofur film made from optical grade polycarbonate using a scalable combination of hot embossing and hot pulling techniques. During fabrication, heated sandblasted steel plates locally elongate softened polymer, thus covering its surface in microcavities surrounded by high aspect ratio micro- and nanohairs. The superhydrophobic nanofur exhibits contact angles of (166+/-6°), low sliding angles (drops below 4% when coated on a polymeric substrate, which can enhance light extraction in organic light emitting diodes (OLEDs). We report an increase of more than 10% in luminous efficacy for a nanofur coated OLED compared to a bare device. Finally, the nanofur film can be used for enhancing the incoupling of light to solar cells, while additionally providing self-cleaning properties. Optical coupling of the nanofur to a multi-crystalline silicon solar cell results in a 5.8% gain in photocurrent compared to a bare device under normal incidence.

Temperatures of the Ocular Surface, Lid, and Periorbital Regions of Sjögren's, Evaporative, and Aqueous-Deficient Dry Eyes Relative to Normals.

Science.gov (United States)

Abreau, Kerstin; Callan, Christine; Kottaiyan, Ranjini; Zhang, Aizhong; Yoon, Geunyoung; Aquavella, James V; Zavislan, James; Hindman, Holly B

2016-01-01

To compare the temperatures of the ocular surface, eyelid, and periorbital skin in normal eyes with Sjögren's syndrome (SS) eyes, evaporative dry eyes (EDE), and aqueous deficient dry eyes (ADDE). 10 eyes were analyzed in each age-matched group (normal, SS, EDE, and ADDE). A noninvasive infrared thermal camera captured two-dimensional images in three regions of interest (ROI) in each of three areas: the ocular surface, the upper eyelid, and the periorbital skin within a controlled environmental chamber. Mean temperatures in each ROI were calculated from the videos. Ocular surface time-segmented cooling rates were calculated over a 5-s blink interval. Relative to normal eyes, dry eyes had lower initial central OSTs (SS -0.71°C, EDE -0.55°C, ADDE -0.95°C, KW Peyes had the lowest initial central OST (Peyes had the lowest central lid temperature and lower periorbital temperatures (Pdry eye. Copyright © 2016 Elsevier Inc. All rights reserved.

Challenges in realizing ultraflat materials surfaces

Directory of Open Access Journals (Sweden)

Takashi Yatsui

2013-12-01

Full Text Available Ultraflat surface substrates are required to achieve an optimal performance of future optical, electronic, or optoelectronic devices for various applications, because such surfaces reduce the scattering loss of photons, electrons, or both at the surfaces and interfaces. In this paper, we review recent progress toward the realization of ultraflat materials surfaces. First, we review the development of surface-flattening techniques. Second, we briefly review the dressed photon–phonon (DPP, a nanometric quasiparticle that describes the coupled state of a photon, an electron, and a multimode-coherent phonon. Then, we review several recent developments based on DPP-photochemical etching and desorption processes, which have resulted in angstrom-scale flat surfaces. To confirm that the superior flatness of these surfaces that originated from the DPP process, we also review a simplified mathematical model that describes the scale-dependent effects of optical near-fields. Finally, we present the future outlook for these technologies.

Exploring single-layered SnSe honeycomb polymorphs for optoelectronic and photovoltaic applications

Science.gov (United States)

Ul Haq, Bakhtiar; AlFaify, S.; Ahmed, R.; Butt, Faheem K.; Laref, A.; Shkir, Mohd.

2018-02-01

Single-layered tin selenide that shares the same structure with phosphorene and possesses intriguing optoelectronic properties has received great interest as a two-dimensional material beyond graphene and phosphorene. Herein, we explore the optoelectronic response of the newly discovered stable honeycomb derivatives (such as α , β , γ , δ , and ɛ ) of single-layered SnSe in the framework of density functional theory. The α , β , γ , and δ derivatives of a SnSe monolayer have been found to exhibit an indirect band gap, however, the dispersion of their band-gap edges demonstrates multiple direct band gaps at a relatively high energy. The ɛ -SnSe, however, features an intrinsic direct band gap at the high-symmetry Γ point. Their energy band gaps (0.53, 2.32, 1.52, 1.56, and 1.76 eV for α -, β -, γ -, δ -, and ɛ -SnSe, respectively), calculated at the level of the Tran-Blaha modified Becke-Johnson approach, mostly fall right in the visible range of the electromagnetic spectrum and are in good agreement with the available literature. The optical spectra of these two-dimensional (2D) SnSe polymorphs (besides β -SnSe) are highly anisotropic and possess strictly different optical band gaps along independent diagonal components. They show high absorption in the visible and UV ranges. Similarly, the reflectivity, refraction, and optical conductivities inherit strong anisotropy from the dielectric functions as well and are highly visible-UV polarized along the cartesian coordinates, showing them to be suitable for optical filters, polarizers, and shields against UV radiation. Our investigations suggest these single-layered SnSe allotropes as a promising 2D material for next-generation nanoscale optoelectronic and photovoltaic applications beyond graphene and phosphorene.

Features of the piezo-phototronic effect on optoelectronic devices based on wurtzite semiconductor nanowires.

Science.gov (United States)

Yang, Qing; Wu, Yuanpeng; Liu, Ying; Pan, Caofeng; Wang, Zhong Lin

2014-02-21

The piezo-phototronic effect, a three way coupling effect of piezoelectric, semiconductor and photonic properties in non-central symmetric semiconductor materials, utilizing the piezo-potential as a "gate" voltage to tune the charge transport/generation/recombination and modulate the performance of optoelectronic devices, has formed a new field and attracted lots of interest recently. The mechanism was verified in various optoelectronic devices such as light emitting diodes (LEDs), photodetectors and solar cells etc. The fast development and dramatic increasing interest in the piezo-phototronic field not only demonstrate the way the piezo-phototronic effects work, but also indicate the strong need for further research in the physical mechanism and potential applications. Furthermore, it is important to distinguish the contribution of the piezo-phototronic effect from other factors induced by external strain such as piezoresistance, band shifting or contact area change, which also affect the carrier behaviour and device performance. In this perspective, we review our recent progress on piezo-phototronics and especially focus on pointing out the features of piezo-phototronic effect in four aspects: I-V characteristics; c-axis orientation; influence of illumination; and modulation of carrier behaviour. Finally we proposed several criteria for describing the contribution made by the piezo-phototronic effect to the performance of optoelectronic devices. This systematic analysis and comparison will not only help give an in-depth understanding of the piezo-phototronic effect, but also work as guide for the design of devices in related areas.

78 FR 16296 - Certain Optoelectronic Devices for Fiber Optic Communications, Components Thereof, and Products...

Science.gov (United States)

2013-03-14

... Fiber Optic Communications, Components Thereof, and Products Containing Same; Commission Determination... United States after importation of certain optoelectronic devices for fiber optic communications... Fiber IP (Singapore) Pte. Ltd. of Singapore (``Avago Fiber IP''); Avago General IP and Avago...

Influence of TiO2 Nanoparticles on Enhancement of Optoelectronic Properties of PFO-Based Light Emitting Diode

Directory of Open Access Journals (Sweden)

Bandar Ali Al-Asbahi

2013-01-01

Full Text Available Improvement on optoelectronic properties of poly (9,9′-di-n-octylfluorenyl-2.7-diyl- (PFO- based light emitting diode upon incorporation of TiO2 nanoparticles (NPs is demonstrated. The PFO/TiO2 nanocomposites with different weight ratios between 5 and 35 wt.% were prepared using solution blending method before they were spin coated onto Indium Tin Oxide substrate. Then a thin Al layer was deposited onto the nanocomposite layer to act as top electrode. The nanocomposites were tested as emissive layer in organic light emitting diodes (OLEDs. The TiO2 NPs played the most crucial role in facilitating charge transport and electrical injection and thus improved device performance in terms of turn-on voltage, electroluminescence spectra (EL, luminance, and luminance efficiency. The best composition was OLED with 5 wt.% TiO2 NPs content having moderate surface roughness and well distribution of NPs. The device performance was reduced at higher TiO2 NPs content due to higher surface roughness and agglomeration of TiO2 NPs. This work demonstrated the importance of optimum TiO2 NPs content with uniform distribution and controlled surface roughness of the emissive layer for better device performance.

Optoelectronic insights into the photovoltaic losses from photocurrent, voltage, and energy perspectives

Science.gov (United States)

Shang, Aixue; An, Yidan; Ma, Dong; Li, Xiaofeng

2017-08-01

Photocurrent and voltage losses are the fundamental limitations for improving the efficiency of photovoltaic devices. It is indeed that a comprehensive and quantitative differentiation of the performance degradation in solar cells will promote the understanding of photovoltaic physics as well as provide a useful guidance to design highly-efficient and cost-effective solar cells. Based on optoelectronic simulation that addresses electromagnetic and carrier-transport responses in a coupled finite-element method, we report a detailed quantitative analysis of photocurrent and voltage losses in solar cells. We not only concentrate on the wavelength-dependent photocurrent loss, but also quantify the variations of photocurrent and operating voltage under different forward electrical biases. Further, the device output power and power losses due to carrier recombination, thermalization, Joule heat, and Peltier heat are studied through the optoelectronic simulation. The deep insight into the gains and losses of the photocurrent, voltage, and energy will contribute to the accurate clarifications of the performance degradation of photovoltaic devices, enabling a better control of the photovoltaic behaviors for high performance.

Surface-segregated monolayers: a new type of ordered monolayer for surface modification of organic semiconductors.

Science.gov (United States)

Wei, Qingshuo; Tajima, Keisuke; Tong, Yujin; Ye, Shen; Hashimoto, Kazuhito

2009-12-09

We report a new type of ordered monolayer for the surface modification of organic semiconductors. Fullerene derivatives with fluorocarbon chains ([6,6]-phenyl-C(61)-buryric acid 1H,1H-perfluoro-1-alkyl ester or FC(n)) spontaneously segregated as a monolayer on the surface of a [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) film during a spin-coating process from the mixture solutions, as confirmed by X-ray photoelectron spectroscopy (XPS). Ultraviolet photoelectron spectroscopy (UPS) showed the shift of ionization potentials (IPs) depending on the fluorocarbon chain length, indicating the formation of surface dipole moments. Surface-sensitive vibrational spectroscopy, sum frequency generation (SFG) revealed the ordered molecular orientations of the C(60) moiety in the surface FC(n) layers. The intensity of the SFG signals from FC(n) on the surface showed a clear odd-even effect when the length of the fluorocarbon chain was changed. This new concept of the surface-segregated monolayer provides a facile and versatile approach to modifying the surface of organic semiconductors and is applicable to various organic optoelectronic devices.

Investigation of mixed saliva by optoelectronic methods

Science.gov (United States)

Savchenko, Ekaterina; Nepomnyashchaya, Elina; Baranov, Maksim; Velichko, Elena; Aksenov, Evgenii; Bogomaz, Tatyana

2018-04-01

At present, saliva and its properties are being actively studied. Human saliva is a unique biological material that has potential in clinical practice. A detailed analysis of the characteristics and properties of saliva is relevant for diagnostic purposes. In this paper, the properties and characteristics of saliva are studied using optoelectronic methods: dynamic light scattering, electrophoretic light scattering and optical microscopy. Mixed saliva from a healthy patient and patient with diabetes mellitus type 2 was used as an object of the study. The dynamics of the behavior of a healthy and patient with diabetes mellitus type 2 is visible according to the results obtained. All three methods confirm hypothesis of structural changes in mixed saliva in the disease of diabetes mellitus type 2.

Optoelectronic iron detectors for pharmaceutical flow analysis.

Science.gov (United States)

Rybkowska, Natalia; Koncki, Robert; Strzelak, Kamil

2017-10-25

Compact flow-through optoelectronic detectors fabricated by pairing of light emitting diodes have been applied for development of economic flow analysis systems dedicated for iron ions determination. Three analytical methods with different chromogens selectively recognizing iron ions have been compared. Ferrozine and ferene S based methods offer higher sensitivity and slightly lower detection limits than method with 1,10-phenantroline, but narrower ranges of linear response. Each system allows detection of iron in micromolar range of concentration with comparable sample throughput (20 injections per hour). The developed flow analysis systems have been successfully applied for determination of iron in diet supplements. The utility of developed analytical systems for iron release studies from drug formulations has also been demonstrated. Copyright © 2017 Elsevier B.V. All rights reserved.

Selection of physiological parameters for optoelectronic system supporting behavioral therapy of autistic children

Science.gov (United States)

Landowska, A.; Karpienko, K.; Wróbel, M.; Jedrzejewska-Szczerska, M.

2014-11-01

In this article the procedure of selection of physiological parameters for optoelectronic system supporting behavioral therapy of autistic children is proposed. Authors designed and conducted an experiment in which a group of 30 health volunteers (16 females and 14 males) were examined. Under controlled conditions people were exposed to a stressful situation caused by the picture or sound (1kHz constant sound, which was gradually silenced and finished with a shot sound). For each of volunteers, a set of physiological parameters were recorded, including: skin conductance, heart rate, peripheral temperature, respiration rate and electromyography. The selected characteristics were measured in different locations in order to choose the most suitable one for the designed therapy supporting system. The bio-statistical analysis allowed us to discern the proper physiological parameters that are most associated to changes due to emotional state of a patient, such as: skin conductance, temperatures and respiration rate. This allowed us to design optoelectronic sensors network for supporting behavioral therapy of children with autism.

Size-tunable band alignment and optoelectronic properties of transition metal dichalcogenide van der Waals heterostructures

Science.gov (United States)

Zhao, Yipeng; Yu, Wangbing; Ouyang, Gang

2018-01-01

2D transition metal dichalcogenide (TMDC)-based heterostructures exhibit several fascinating properties that can address the emerging market of energy conversion and storage devices. Current achievements show that the vertical stacked TMDC heterostructures can form type II band alignment and possess significant optoelectronic properties. However, a detailed analytical understanding of how to quantify the band alignment and band offset as well as the optimized power conversion efficiency (PCE) is still lacking. Herein, we propose an analytical model to exhibit the PCEs of TMDC van der Waals (vdW) heterostructures and explore the intrinsic mechanism of photovoltaic conversion based on the detailed balance principle and atomic-bond-relaxation correlation mechanism. We find that the PCE of monolayer MoS2/WSe2 can be up to 1.70%, and that of the MoS2/WSe2 vdW heterostructures increases with thickness, owing to increasing optical absorption. Moreover, the results are validated by comparing them with the available evidence, providing realistic efficiency targets and design principles. Highlights • Both electronic and optoelectronic models are developed for vertical stacked MoS2/WSe2 heterostructures. • The underlying mechanism on size effect of electronic and optoelectronic properties for vertical stacked MoS2/WSe2 heterostructures is clarified. • The macroscopically measurable quantities and the microscopical bond identities are connected.

Organic Optoelectronic Devices Employing Small Molecules

Science.gov (United States)

Fleetham, Tyler Blain

Organic optoelectronic devices have remained a research topic of great interest over the past two decades, particularly in the development of efficient organic photovoltaics (OPV) and organic light emitting diodes (OLED). In order to improve the efficiency, stability, and materials variety for organic optoelectronic devices a number of emitting materials, absorbing materials, and charge transport materials were developed and employed in a device setting. Optical, electrical, and photophysical studies of the organic materials and their corresponding devices were thoroughly carried out. Two major approaches were taken to enhance the efficiency of small molecule based OPVs: developing material with higher open circuit voltages or improved device structures which increased short circuit current. To explore the factors affecting the open circuit voltage (VOC) in OPVs, molecular structures were modified to bring VOC closer to the effective bandgap, DeltaE DA, which allowed the achievement of 1V VOC for a heterojunction of a select Ir complex with estimated exciton energy of only 1.55eV. Furthermore, the development of anode interfacial layer for exciton blocking and molecular templating provide a general approach for enhancing the short circuit current. Ultimately, a 5.8% PCE was achieved in a single heterojunction of C60 and a ZnPc material prepared in a simple, one step, solvent free, synthesis. OLEDs employing newly developed deep blue emitters based on cyclometalated complexes were demonstrated. Ultimately, a peak EQE of 24.8% and nearly perfect blue emission of (0.148,0.079) was achieved from PtON7dtb, which approaches the maximum attainable performance from a blue OLED. Furthermore, utilizing the excimer formation properties of square-planar Pt complexes, highly efficient and stable white devices employing a single emissive material were demonstrated. A peak EQE of over 20% for pure white color (0.33,0.33) and 80 CRI was achieved with the tridentate Pt complex, Pt

Performance and calibration of the CHORUS scintillating fiber tracker and opto-electronics readout system

International Nuclear Information System (INIS)

Annis, P.; Aoki, S.; Brunner, J.; De Jong, M.; Fabre, J.P.; Ferreira, R.; Flegel, W.; Frekers, D.; Gregoire, G.; Herin, J.; Kobayashi, M.; Konijn, J.; Lemaitre, V.; Macina, D.; Meijer Drees, R.; Meinhard, H.; Michel, L.; Mommaert, C.; Nakamura, K.; Nakamura, M.; Nakano, T.; Niwa, K.; Niu, E.; Panman, J.; Riccardi, F.; Rondeshagen, D.; Sato, O.; Stefanini, G.; Vander Donckt, M.; Vilain, P.; Wilquet, G.; Winter, K.; Wong, H.T.

1995-01-01

An essential component of the CERN WA95/CHORUS experiment is a scintillating fiber tracker system for precise track reconstruction of particles. The tracker design, its opto-electronics readout and calibration system are discussed. Performances of the detector are presented. (orig.)

78 FR 77166 - Certain Optoelectronic Devices for Fiber Optic Communications, Components Thereof, and Products...

Science.gov (United States)

2013-12-20

... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-860] Certain Optoelectronic Devices for Fiber Optic Communications, Components Thereof, and Products Containing the Same; Notice of Request for Statements on the Public Interest AGENCY: U.S. International Trade Commission. ACTION: Notice. SUMMARY...

Tuning Optoelectronic Properties of Ambipolar Organic Light-Emitting Transistors Using a Bulk-Heterojunction Approach

NARCIS (Netherlands)

Loi, Maria Antonietta; Rost-Bietsch, Constance; Murgia, Mauro; Karg, Siegfried; Riess, Walter; Muccini, Michele

2006-01-01

Bulk-heterojunction engineering is demonstrated as an approach to producing ambipolar organic light-emitting field-effect transistors with tunable electrical and optoelectronic characteristics. The electron and hole mobilities, as well as the electroluminescence intensity, can be tuned over a large

Treatment of surfaces with low-energy electrons

Czech Academy of Sciences Publication Activity Database

Frank, Luděk; Mikmeková, Eliška; Lejeune, M.

2017-01-01

Roč. 407, JUN 15 (2017), s. 105-108 ISSN 0169-4332 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : Low- energy electrons * Electron beam induced release * Graphene * Ultimate cleaning of surfaces Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Nano-processes (applications on nano-scale) Impact factor: 3.387, year: 2016

Theoretical analysis of a fiber optic surface plasmon resonance sensor utilizing a Bragg grating

Czech Academy of Sciences Publication Activity Database

Špačková, Barbora; Homola, Jiří

2009-01-01

Roč. 17, č. 25 (2009), s. 23254-23264 ISSN 1094-4087 Institutional research plan: CEZ:AV0Z20670512 Keywords : Surface plasmon resonance * Fiber optic * Bragg grating * Biosensor * Coupled mode theory Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.278, year: 2009

Hydrogen-enriched non-premixed jet flames : analysis of the flame surface, flame normal, flame index and Wobbe index

NARCIS (Netherlands)

Ranga Dinesh, K.K.J.; Jiang, X.; Oijen, van J.A.

2014-01-01

A non-premixed impinging jet flame is studied using three-dimensional direct numerical simulation with detailed chemical kinetics in order to investigate the influence of fuel variability on flame surface, flame normal, flame index and Wobbe index for hydrogen-enriched combustion. Analyses indicate

Optoelectronic circuits in nanometer CMOS technology

CERN Document Server

Atef, Mohamed

2016-01-01

This book describes the newest implementations of integrated photodiodes fabricated in nanometer standard CMOS technologies. It also includes the required fundamentals, the state-of-the-art, and the design of high-performance laser drivers, transimpedance amplifiers, equalizers, and limiting amplifiers fabricated in nanometer CMOS technologies. This book shows the newest results for the performance of integrated optical receivers, laser drivers, modulator drivers and optical sensors in nanometer standard CMOS technologies. Nanometer CMOS technologies rapidly advanced, enabling the implementation of integrated optical receivers for high data rates of several Giga-bits per second and of high-pixel count optical imagers and sensors. In particular, low cost silicon CMOS optoelectronic integrated circuits became very attractive because they can be extensively applied to short-distance optical communications, such as local area network, chip-to-chip and board-to-board interconnects as well as to imaging and medical...

Correlation of Defect-Related Optoelectronic Properties in Zn5(OH6(CO32/ZnO Nanostructures with Their Quasi-Fractal Dimensionality

Directory of Open Access Journals (Sweden)

J. Antonio Paramo

2015-01-01

Full Text Available Hydrozincite (Zn5(OH6(CO32 is, among others, a popular precursor used to synthesize nanoscale ZnO with complex morphologies. For many existing and potential applications utilizing nanostructures, performance is determined by the surface and subsurface properties. Current understanding of the relationship between the morphology and the defect properties of nanocrystalline ZnO and hydrozincite systems is still incomplete. Specifically, for the latter nanomaterial the structure-property correlations are largely unreported in the literature despite the extensive use of hydrozincite in the synthesis applications. In our work, we addressed this issue by studying precipitated nanostructures of Zn5(OH6(CO32 with varying quasi-fractal dimensionalities containing relatively small amounts of a ZnO phase. Crystal morphology of the samples was accurately controlled by the growth time. We observed a strong correlation between the morphology of the samples and their optoelectronic properties. Our results indicate that a substantial increase of the free surface in the nanocrystal samples generates higher relative concentration of defects, consistent with the model of defect-rich surface and subsurface layers.

Flip-chip bonded optoelectronic integration based on ultrathin silicon (UTSi) CMOS

Science.gov (United States)

Hong, Sunkwang; Ho, Tawei; Zhang, Liping; Sawchuk, Alexander A.

2003-06-01

We describe the design and test of flip-chip bonded optoelectronic CMOS devices based on Peregrine Semiconductor's 0.5 micron Ultra-Thin Silicon on sapphire (UTSi) technology. The UTSi process eliminates the substrate leakage that typically results in crosstalk and reduces parasitic capacitance to the substrate, providing many benefits compared to bulk silicon CMOS. The low-loss synthetic sapphire substrate is optically transparent and has a coefficient of thermal expansion suitable for flip-chip bonding of vertical cavity surface emitting lasers (VCSELs) and detectors. We have designed two different UTSi CMOS chips. One contains a flip-chip bonded 1 x 4 photodiode array, a receiver array, a double edge triggered D-flip flop-based 2047-pattern pseudo random bit stream (PRBS) generator and a quadrature-phase LC-voltage controlled oscillator (VCO). The other chip contains a flip-chip bonded 1 x 4 VCSEL array, a driver array based on high-speed low-voltage differential signals (LVDS) and a full-balanced differential LC-VCO. Each VCSEL driver and receiver has individual input and bias voltage adjustments. Each UTSi chip is mounted on different printed circuit boards (PCBs) which have holes with about 1 mm radius for optical output and input paths through the sapphire substrate. We discuss preliminary testing of these chips.

Two-dimensional optoelectronic interconnect-processor and its operational bit error rate

Science.gov (United States)

Liu, J. Jiang; Gollsneider, Brian; Chang, Wayne H.; Carhart, Gary W.; Vorontsov, Mikhail A.; Simonis, George J.; Shoop, Barry L.

2004-10-01

Two-dimensional (2-D) multi-channel 8x8 optical interconnect and processor system were designed and developed using complementary metal-oxide-semiconductor (CMOS) driven 850-nm vertical-cavity surface-emitting laser (VCSEL) arrays and the photodetector (PD) arrays with corresponding wavelengths. We performed operation and bit-error-rate (BER) analysis on this free-space integrated 8x8 VCSEL optical interconnects driven by silicon-on-sapphire (SOS) circuits. Pseudo-random bit stream (PRBS) data sequence was used in operation of the interconnects. Eye diagrams were measured from individual channels and analyzed using a digital oscilloscope at data rates from 155 Mb/s to 1.5 Gb/s. Using a statistical model of Gaussian distribution for the random noise in the transmission, we developed a method to compute the BER instantaneously with the digital eye-diagrams. Direct measurements on this interconnects were also taken on a standard BER tester for verification. We found that the results of two methods were in the same order and within 50% accuracy. The integrated interconnects were investigated in an optoelectronic processing architecture of digital halftoning image processor. Error diffusion networks implemented by the inherently parallel nature of photonics promise to provide high quality digital halftoned images.

Controlling and modelling the wetting properties of III-V semiconductor surfaces using re-entrant nanostructures.

Science.gov (United States)

Ng, Wing H; Lu, Yao; Liu, Huiyun; Carmalt, Claire J; Parkin, Ivan P; Kenyon, Anthony J

2018-02-23

Inorganic semiconductors such as III-V materials are very important in our everyday life as they are used for manufacturing optoelectronic and microelectronic components with important applications span from energy harvesting to telecommunications. In some applications, these components are required to operate in harsh environments. In these cases, having waterproofing capability is essential. Here we demonstrate design and control of the wettability of indium phosphide based multilayer material (InP/InGaAs/InP) using re-entrant structures fabricated by a fast electron beam lithography technique. This patterning technique enabled us to fabricate highly uniform nanostructure arrays with at least one order of magnitude shorter patterning times compared to conventional electron beam lithography methods. We reduced the surface contact fraction significantly such that the water droplets may be completely removed from our nanostructured surface. We predicted the wettability of our patterned surface by modelling the adhesion energies between the water droplet and both the patterned surface and the dispensing needle. This is very useful for the development of coating-free waterproof optoelectronic and microelectronic components where the coating may hinder the performance of such devices and cause problems with semiconductor fabrication compatibility.

Optoelectronic device for the measurement of the absolute linear position in the micrometric displacement range

Science.gov (United States)

Morlanes, Tomas; de la Pena, Jose L.; Sanchez-Brea, Luis M.; Alonso, Jose; Crespo, Daniel; Saez-Landete, Jose B.; Bernabeu, Eusebio

2005-07-01

In this work, an optoelectronic device that provides the absolute position of a measurement element with respect to a pattern scale upon switch-on is presented. That means that there is not a need to perform any kind of transversal displacement after the startup of the system. The optoelectronic device is based on the process of light propagation passing through a slit. A light source with a definite size guarantees the relation of distances between the different elements that constitute our system and allows getting a particular optical intensity profile that can be measured by an electronic post-processing device providing the absolute location of the system with a resolution of 1 micron. The accuracy of this measuring device is restricted to the same limitations of any incremental position optical encoder.

Monitoring RAYT activity by surface plasmon resonance biosensor

Czech Academy of Sciences Publication Activity Database

Bocková, Markéta; Špringer, Tomáš; Nečasová, Iva; Nunvář, Jaroslav; Schneider, Bohdan; Homola, Jiří

2015-01-01

Roč. 407, č. 14 (2015), s. 3985-3993 ISSN 1618-2642 R&D Projects: GA ČR GAP305/12/1801 Grant - others:GA MŠk(CZ) CZ.1.05/1.1.00/02.0109 Institutional support: RVO:67985882 ; RVO:86652036 Keywords : Surface plasmon resonance * Biosensor * REP-associated tyrosine transposase Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering; EB - Genetics ; Molecular Biology (BTO-N) Impact factor: 3.125, year: 2015

Combined experimental–theoretical study of the optoelectronic properties of non-stoichiometric pyrochlore bismuth titanate

KAUST Repository

Noureldine, Dalal; Lardhi, Sheikha F.; Ziani, Ahmed; Harb, Moussab; Cavallo, Luigi; Takanabe, Kazuhiro

2015-01-01

A combination of experimental and computational methods was applied to investigate the crystal structure and optoelectronic properties of the non-stoichiometric pyrochlore Bi2−xTi2O7−1.5x. The detailed experimental protocol for both powder and thin

Novel soluble fluorene-thienothiadiazole and fluorene-carbazole copolymers for optoelectronics

Czech Academy of Sciences Publication Activity Database

Cimrová, Věra; Kmínek, Ivan; Výprachtický, Drahomír

2010-01-01

Roč. 295, č. 1 (2010), s. 65-70 ISSN 1022-1360. [Prague Meetings on Macromolecules /73./ New Frontiers in Macromolecular Science: From Macromolecular Concepts of Living Matter to Polymers for Better Quality of Life. Prague, 05.07.2009-09.07.2009] R&D Projects: GA MŠk(CZ) 1M06031; GA AV ČR IAA4050409 Institutional research plan: CEZ:AV0Z40500505 Keywords : fluorene – thienothiadiazole copolymers * photovoltaics * fluorene-carbazole copolymers Subject RIV: JA - Electronics ; Optoelectronics , Electrical Engineering

Surface reconstruction processes in MO VPE grown GaAs layers

Czech Academy of Sciences Publication Activity Database

Nohavica, Dušan

1999-01-01

Roč. 50, 2/s (1999), s. 24-25 ISSN 1335-3632. [Development of Materials Science in Research and Education - DMS -RE 1998 /8./. Zlenice, 08.09.1998-10.09.1998] R&D Projects: GA AV ČR IAA2067901 Institutional research plan: CEZ:AV0Z2067918 Keywords : epitaxial growth * surface reconstruction Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Analysis of surface states in ZnO nanowire field effect transistors

International Nuclear Information System (INIS)

Shao, Ye; Yoon, Jongwon; Kim, Hyeongnam; Lee, Takhee; Lu, Wu

2014-01-01

Highlights: • The electron transport in ZnO nanowire FETs is space charged limited below a trap temperature. • Metallic contacts to ZnO nanowires exhibit non-linear behavior with a Schottky barrier height of ∼0.35 eV. • The surface state density is in the range of 1.04 × 10 10 –1.24 × 10 10 /cm 2 . • The trap activation energy is ∼0.26 eV. - Abstract: Nanowires (NWs) have attracted considerable interests for scaled electronic and optoelectronic device applications. However, NW based semiconductor devices normally suffer from surface states due to the existence of dangling bonds or surface reconstruction. Because of their large surface-to-volume ratio, surface states in NWs can easily affect the metallic contacts to NWs and electron transport in NW. Here, we present ZnO NW surface analysis by performing current–voltage characterization on ZnO NW Schottky barrier field effect transistors with different metal contacts (Ti, Al, Au) at both room temperature and cryogenic temperature. Our results show that three metal contacts are all Schottky contacts to ZnO NWs due to surface states. Our further study reveals: (a) the surface states related Schottky barrier height (SBH) can be extracted from a back to back Schottky diodes model and the SBH values are in the range of 0.34–0.37 eV for three metal contacts; (b) the trap activation energy determined from the Arrhenius plots of different Schottky metal contacts is in the range of 0.23–0.29 eV, which is oxygen vacancies related; and (c) based on the space-charge-limited model, the surface state density of ZnO NW is in the range of 1.04 × 10 10 –1.24 × 10 10 /cm 2

Optical modeling based on mean free path calculations for quantum dot phosphors applied to optoelectronic devices.

Science.gov (United States)

Shin, Min-Ho; Kim, Hyo-Jun; Kim, Young-Joo

2017-02-20

We proposed an optical simulation model for the quantum dot (QD) nanophosphor based on the mean free path concept to understand precisely the optical performance of optoelectronic devices. A measurement methodology was also developed to get the desired optical characteristics such as the mean free path and absorption spectra for QD nanophosphors which are to be incorporated into the simulation. The simulation results for QD-based white LED and OLED displays show good agreement with the experimental values from the fabricated devices in terms of spectral power distribution, chromaticity coordinate, CCT, and CRI. The proposed simulation model and measurement methodology can be applied easily to the design of lots of optoelectronics devices using QD nanophosphors to obtain high efficiency and the desired color characteristics.

Tunable band gap emission and surface passivation of germanium nanocrystals synthesized in the gas phase

NARCIS (Netherlands)

Wheeler, LM; Levij, L.M.; Kortshagen, U.R.

2013-01-01

The narrow bulk band gap and large exciton Bohr radius of germanium (Ge) make it an attractive material for optoelectronics utilizing band-gap-tunable photoluminescence (PL). However, realization of PL due to quantum confinement remains scarcely reported. Instead, PL is often observed from surface

Thickness effect on the microstructure, morphology and optoelectronic properties of ZnS films

International Nuclear Information System (INIS)

Prathap, P; Revathi, N; Subbaiah, Y P Venkata; Reddy, K T Ramakrishna

2008-01-01

Thin films of ZnS with thicknesses ranging from 100 to 600 nm have been deposited on glass substrates by close spaced thermal evaporation. All the films were grown at the same deposition conditions except the deposition time. The effect of thickness on the physical properties of ZnS films has been studied. The experimental results indicated that the thickness affects the structure, lattice strain, surface morphology and optoelectronic properties of ZnS films significantly. The films deposited at a thickness of 100 nm showed hexagonal structure whereas films of thickness 300 nm or more showed cubic structure. However, coexistence of both cubic and hexagonal structures was observed in the films of 200 nm thickness. The surface roughness of the films showed an increasing trend at higher thicknesses of the films. A blue-shift in the energy band gap along with an intense UV emission band was observed with the decrease of film thickness, which are ascribed to the quantum confinement effect. The behaviour of optical constants such as refractive index and extinction coefficient were analysed. The variation of refractive index and extinction coefficient with thickness was explained on the basis of the contribution from the packing density of the layers. The electrical resistivity as well as the activation energy were evaluated and found to decrease with the increase of film thickness. The thickness had a significant influence on the optical band gap as well as the luminescence intensity

Optoelectronic imaging of speckle using image processing method

Science.gov (United States)

Wang, Jinjiang; Wang, Pengfei

2018-01-01

A detailed image processing of laser speckle interferometry is proposed as an example for the course of postgraduate student. Several image processing methods were used together for dealing with optoelectronic imaging system, such as the partial differential equations (PDEs) are used to reduce the effect of noise, the thresholding segmentation also based on heat equation with PDEs, the central line is extracted based on image skeleton, and the branch is removed automatically, the phase level is calculated by spline interpolation method, and the fringe phase can be unwrapped. Finally, the imaging processing method was used to automatically measure the bubble in rubber with negative pressure which could be used in the tire detection.

Direct olefination of fluorinated benzothiadiazoles: a new entry to optoelectronic materials.

Science.gov (United States)

Xiao, Yu-Lan; Zhang, Bo; He, Chun-Yang; Zhang, Xingang

2014-04-14

Fluorinated olefin-containing benzothiadiazoles have important applications in optoelectronic materials. Herein, we reported the direct olefination of fluorinated benzothiadiazoles, as catalyzed by palladium. The reaction proceeds under mild reaction conditions and shows high functional-group compatibility. A preliminary study of the properties of the resulting symmetrical and unsymmetrical olefin-containing fluorinated benzothiadiazoles in red-light-emitting dyes has also been conducted. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Concept of Quantum Geometry in Optoelectronic Processes in Solids: Application to Solar Cells.

Science.gov (United States)

Nagaosa, Naoto; Morimoto, Takahiro

2017-07-01

The concept of topology is becoming more and more relevant to the properties and functions of electronic materials including various transport phenomena and optical responses. A pedagogical introduction is given here to the basic ideas and their applications to optoelectronic processes in solids. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of surface passivation on twin-free GaAs nanosheets.

Science.gov (United States)

Arab, Shermin; Chi, Chun-Yung; Shi, Teng; Wang, Yuda; Dapkus, Daniel P; Jackson, Howard E; Smith, Leigh M; Cronin, Stephen B

2015-02-24

Unlike nanowires, GaAs nanosheets exhibit no twin defects, stacking faults, or dislocations even when grown on lattice mismatched substrates. As such, they are excellent candidates for optoelectronic applications, including LEDs and solar cells. We report substantial enhancements in the photoluminescence efficiency and the lifetime of passivated GaAs nanosheets produced using the selected area growth (SAG) method with metal organic chemical vapor deposition (MOCVD). Measurements are performed on individual GaAs nanosheets with and without an AlGaAs passivation layer. Both steady-state photoluminescence and time-resolved photoluminescence spectroscopy are performed to study the optoelectronic performance of these nanostructures. Our results show that AlGaAs passivation of GaAs nanosheets leads to a 30- to 40-fold enhancement in the photoluminescence intensity. The photoluminescence lifetime increases from less than 30 to 300 ps with passivation, indicating an order of magnitude improvement in the minority carrier lifetime. We attribute these enhancements to the reduction of nonradiative recombination due to the compensation of surface states after passivation. The surface recombination velocity decreases from an initial value of 2.5 × 10(5) to 2.7 × 10(4) cm/s with passivation.

Graphene and Carbon-Nanotube Nanohybrids Covalently Functionalized by Porphyrins and Phthalocyanines for Optoelectronic Properties.

Science.gov (United States)

Wang, Aijian; Ye, Jun; Humphrey, Mark G; Zhang, Chi

2018-04-01

In recent years, there has been a rapid growth in studies of the optoelectronic properties of graphene, carbon nanotubes (CNTs), and their derivatives. The chemical functionalization of graphene and CNTs is a key requirement for the development of this field, but it remains a significant challenge. The focus here is on recent advances in constructing nanohybrids of graphene or CNTs covalently linked to porphyrins or phthalocyanines, as well as their application in nonlinear optics. Following a summary of the syntheses of nanohybrids constructed from graphene or CNTs and porphyrins or phthalocyanines, explicit intraconjugate electronic interactions between photoexcited porphyrins/phthalocyanines and graphene/CNTs are introduced classified by energy transfer, electron transfer, and charge transfer, and their optoelectronic applications are also highlighted. The major current challenges for the development of covalently linked nanohybrids of porphyrins or phthalocyanines and carbon nanostructures are also presented. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Broadband enhancement of photoluminance from colloidal metal halide perovskite nanocrystals on plasmonic nanostructured surfaces.

Science.gov (United States)

Zhang, Si; Liang, Yuzhang; Jing, Qiang; Lu, Zhenda; Lu, Yanqing; Xu, Ting

2017-11-07

Metal halide perovskite nanocrystals (NCs) as a new kind of promising optoelectronic material have attracted wide attention due to their high photoluminescence (PL) quantum yield, narrow emission linewidth and wideband color tunability. Since the PL intensity always has a direct influence on the performance of optoelectronic devices, it is of vital importance to improve the perovskite NCs' fluorescence emission efficiency. Here, we synthesize three inorganic perovskite NCs and experimentally demonstrate a broadband fluorescence enhancement of perovskite NCs by exploiting plasmonic nanostructured surface consisting of nanogrooves array. The strong near-field optical localization associated with surface plasmon polariton-coupled emission effect generated by the nanogrooves array can significantly boost the absorption of perovskite NCs and tailor the fluorescence emissions. As a result, the PL intensities of perovskite NCs are broadband enhanced with a maximum factor higher than 8-fold achieved in experimental demonstration. Moreover, the high efficiency PL of perovskite NCs embedded in the polymer matrix layer on the top of plasmonic nanostructured surface can be maintained for more than three weeks. These results imply that plasmonic nanostructured surface is a good candidate to stably broadband enhance the PL intensity of perovskite NCs and further promote their potentials in the application of visible-light-emitting devices.

OMNI: An optoelectronic multichannel network interface based on hybrid CMOS-SEED technology

Science.gov (United States)

Pinkston, Timothy M.

1996-11-01

This paper presents a hybrid CMOS-SEED multiprocessor network interface smart pixel design that implements a reservation-based channel control protocol for collisionless concurrent access to multiple optical interprocessor communication channels. An asynchronous optical token is used as the arbitration mechanism for reservation control instead of slotted access. This work demonstrates that complex network protocol functions can be implemented using optoelectronic smart pixel technology.

Optoelectronic Properties and Structural Characterization of GaN Thick Films on Different Substrates through Pulsed Laser Deposition

Directory of Open Access Journals (Sweden)

Wei-Kai Wang

2017-01-01

Full Text Available Approximately 4-μm-thick GaN epitaxial films were directly grown onto a GaN/sapphire template, sapphire, Si(111, and Si(100 substrates by high-temperature pulsed laser deposition (PLD. The influence of the substrate type on the crystalline quality, surface morphology, microstructure, and stress states was investigated by X-ray diffraction (XRD, photoluminescence (PL, atomic force microscopy (AFM, transmission electron microscopy (TEM, and Raman spectroscopy. Raman scattering spectral analysis showed a compressive film stress of −0.468 GPa for the GaN/sapphire template, whereas the GaN films on sapphire, Si(111, and Si(100 exhibited a tensile stress of 0.21, 0.177, and 0.081 GPa, respectively. Comparative analysis indicated the growth of very close to stress-free GaN on the Si(100 substrate due to the highly directional energetic precursor migration on the substrate’s surface and the release of stress in the nucleation of GaN films during growth by the high-temperature (1000 °C operation of PLD. Moreover, TEM images revealed that no significant GaN meltback (Ga–Si etching process was found in the GaN/Si sample surface. These results indicate that PLD has great potential for developing stress-free GaN templates on different substrates and using them for further application in optoelectronic devices.

Opto-electronic DNA chip-based integrated card for clinical diagnostics.

Science.gov (United States)

Marchand, Gilles; Broyer, Patrick; Lanet, Véronique; Delattre, Cyril; Foucault, Frédéric; Menou, Lionel; Calvas, Bernard; Roller, Denis; Ginot, Frédéric; Campagnolo, Raymond; Mallard, Frédéric

2008-02-01

Clinical diagnostics is one of the most promising applications for microfluidic lab-on-a-chip or lab-on-card systems. DNA chips, which provide multiparametric data, are privileged tools for genomic analysis. However, automation of molecular biology protocol and use of these DNA chips in fully integrated systems remains a great challenge. Simplicity of chip and/or card/instrument interfaces is amongst the most critical issues to be addressed. Indeed, current detection systems for DNA chip reading are often complex, expensive, bulky and even limited in terms of sensitivity or accuracy. Furthermore, for liquid handling in the lab-on-cards, many devices use complex and bulky systems, either to directly manipulate fluids, or to ensure pneumatic or mechanical control of integrated valves. All these drawbacks prevent or limit the use of DNA-chip-based integrated systems, for point-of-care testing or as a routine diagnostics tool. We present here a DNA-chip-based protocol integration on a plastic card for clinical diagnostics applications including: (1) an opto-electronic DNA-chip, (2) fluid handling using electrically activated embedded pyrotechnic microvalves with closing/opening functions. We demonstrate both fluidic and electric packaging of the optoelectronic DNA chip without major alteration of its electronical and biological functionalities, and fluid control using novel electrically activable pyrotechnic microvalves. Finally, we suggest a complete design of a card dedicated to automation of a complex biological protocol with a fully electrical fluid handling and DNA chip reading.

Potential fields on the ventricular surface of the exposed dog heart during normal excitation.

Science.gov (United States)

Arisi, G; Macchi, E; Baruffi, S; Spaggiari, S; Taccardi, B

1983-06-01

We studied the normal spread of excitation on the anterior and posterior ventricular surface of open-chest dogs by recording unipolar electrograms from an array of 1124 electrodes spaced 2 mm apart. The array had the shape of the ventricular surface of the heart. The electrograms were processed by a computer and displayed as epicardial equipotential maps at 1-msec intervals. Isochrone maps also were drawn. Several new features of epicardial potential fields were identified: (1) a high number of breakthrough points; (2) the topography, apparent widths, velocities of the wavefronts and the related potential drop; (3) the topography of positive potential peaks in relation to the wavefronts. Fifteen to 24 breakthrough points were located on the anterior, and 10 to 13 on the posterior ventricular surface. Some were in previously described locations and many others in new locations. Specifically, 3 to 5 breakthrough points appeared close to the atrioventricular groove on the anterior right ventricle and 2 to 4 on the posterior heart aspect; these basal breakthrough points appeared when a large portion of ventricular surface was still unexcited. Due to the presence of numerous breakthrough points on the anterior and posterior aspect of the heart which had not previously been described, the spread of excitation on the ventricular surface was "mosaic-like," with activation wavefronts spreading in all directions, rather than radially from the two breakthrough points, as traditionally described. The positive potential peaks which lay ahead of the expanding wavefronts moved along preferential directions which were probably related to the myocardial fiber direction.

Resonant and kinematical enhancement of He scattering from LiF(001) surface and pseudosurface vibrational normal modes

International Nuclear Information System (INIS)

Nichols, W.L.; Weare, J.H.

1986-01-01

One-phonon cross sections calculated from sagittally polarized vibrational normal modes account for most salient inelastic-scattering intensities seen in He-LiF(001) and measurements published by Brusdeylins, Doak, and Toennies. We have found that most inelastic intensities which cannot be attributed to potential resonances can be explained as kinematically enhanced scattering from both surface and pseudosurface bulk modes

OSA Trends in Optics and Photonics Series. Volume 13: Ultrafast Electronics and Optoelectronics

Science.gov (United States)

1997-01-01

tomography. Many materials such as plastics, cardboard, wood and rubber have good transparency in the terahertz frequency range. Hence, this new...Ultrafast processes in semiconductors. Introduction Nonlinear Bragg reflector ( NBR ) consists of periodically distributed optical nonlinearity coexisting...with multiple reflection and group-delay dispersion. Recent theoretical analyses showed the potential of NBR in ultrafast optoelectronics such as all

Toward single-molecule detection with sensors based on propagating surface plasmons

Czech Academy of Sciences Publication Activity Database

Kvasnička, Pavel; Chadt, Karel; Vala, Milan; Bocková, Markéta; Homola, Jiří

2012-01-01

Roč. 37, č. 2 (2012), s. 163-165 ISSN 0146-9592 R&D Projects: GA AV ČR KAN200670701; GA MŠk OC09058; GA MŠk(CZ) LH11102 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical biosenzor * single molecule * surface plasmon microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.385, year: 2012

An optoelectronic integrated device including a laser and its driving circuit

Energy Technology Data Exchange (ETDEWEB)

Matsueda, H.; Nakano, H.; Tanaka, T.P.

1984-10-01

A monolithic optoelectronic integrated circuit (OEIC) including a laser diode, photomonitor and driving and detecting circuits has been fabricated on a semi-insulating GaAs substrate. The OEIC has a horizontal integrating structure which is suitable for realising high-density multifunctional devices. The fabricating process and the static and dynamic characteristics of the optical and electronic elements are described. The preliminary results of the co-operative operation of the laser and its driving circuit are also presented.

Seeing smells: development of an optoelectronic nose

Directory of Open Access Journals (Sweden)

Kenneth S. Suslick

2007-06-01

Full Text Available The development of an array of chemically-responsive dyes on a porous membrane and in its use as a general sensor for odors and volatile organic compounds (VOCs is reviewed. These colorimetric sensor arrays (CSA act as an "optoelectronic nose" by using an array of multiple dyes whose color changes are based on the full range of intermolecular interactions. The CSA is digitally imaged before and after exposure and the resulting difference map provides a digital fingerprint for any VOC or mixture of odorants. The result is an enormous increase in discriminatory power among odorants compared to prior electronic nose technologies. For the detection of biologically important analytes, including amines, carboxylic acids, and thiols, high sensitivities (ppbv have been demonstrated. The array is essentially non-responsive to changes in humidity due to the hydrophobicity of the dyes and membrane.

Surface plasmon resonance biosensor for parallelized detection of protein biomarkers in diluted blood plasma

Czech Academy of Sciences Publication Activity Database

Piliarik, Marek; Bocková, Markéta; Homola, Jiří

2010-01-01

Roč. 26, č. 4 (2010), s. 1656-1661 ISSN 0956-5663 R&D Projects: GA AV ČR KAN200670701 Institutional research plan: CEZ:AV0Z20670512 Keywords : Surface plasmon resonance * Protein array * Cancer marker Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 5.361, year: 2010

Self-Healing Thermal Annealing: Surface Morphological Restructuring Control of GaN Nanorods

Energy Technology Data Exchange (ETDEWEB)

Conroy, Michele; Li, Haoning; Zubialevich, Vitaly Z.; Kusch, Gunnar; Schmidt, Michael; Collins, Timothy; Glynn, Colm; Martin, Robert W.; O’Dwyer, Colm; Morris, Michael D.; Holmes, Justin D.; Parbrook, Peter J.

2016-12-07

With advances in nanolithography and dry etching, top-down methods of nanostructuring have become a widely used tool for improving the efficiency of optoelectronics. These nano dimensions can offer various benefits to the device performance in terms of light extraction and efficiency, but often at the expense of emission color quality. Broadening of the target emission peak and unwanted yellow luminescence are characteristic defect-related effects due to the ion beam etching damage, particularly for III–N based materials. In this article we focus on GaN based nanorods, showing that through thermal annealing the surface roughness and deformities of the crystal structure can be “self-healed”. Correlative electron microscopy and atomic force microscopy show the change from spherical nanorods to faceted hexagonal structures, revealing the temperature-dependent surface morphology faceting evolution. The faceted nanorods were shown to be strain- and defect-free by cathodoluminescence hyperspectral imaging, micro-Raman, and transmission electron microscopy (TEM). In-situ TEM thermal annealing experiments allowed for real time observation of dislocation movements and surface restructuring observed in ex-situ annealing TEM sampling. This thermal annealing investigation gives new insight into the redistribution path of GaN material and dislocation movement post growth, allowing for improved understanding and in turn advances in optoelectronic device processing of compound semiconductors.

High energy electron irradiation effects on Ga-doped ZnO thin films for optoelectronic space applications

Science.gov (United States)

Serrao, Felcy Jyothi; Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.

2018-03-01

Gallium-doped ZnO (GZO) thin films of thickness 394 nm were prepared by a simple, cost-effective sol-gel spin coating method. The effect of 8 MeV electron beam irradiation with different irradiation doses ranging from 0 to 10 kGy on the structural, optical and electrical properties was investigated. Electron irradiation influences the changes in the structural properties and surface morphology of GZO thin films. X-ray diffraction analysis showed that the polycrystalline nature of the GZO films is unaffected by the high energy electron irradiation. The grain size and the surface roughness were found maximum for the GZO film irradiated with 10 kGy electron dosage. The average transmittance of GZO thin films decreased after electron irradiation. The optical band gap of Ga-doped ZnO films was decreased with the increase in the electron dosage. The electrical resistivity of GZO films decreased from 4.83 × 10-3 to 8.725 × 10-4 Ω cm, when the electron dosage was increased from 0 to 10 kGy. The variation in the optical and electrical properties in the Ga-doped ZnO thin films due to electron beam irradiation in the present study is useful in deciding their compatibility in optoelectronic device applications in electron radiation environment.

Growth and surface topography of WSe_2 single crystal

International Nuclear Information System (INIS)

Dixit, Vijay; Vyas, Chirag; Pataniya, Pratik; Jani, Mihir; Pathak, Vishal; Patel, Abhishek; Pathak, V. M.; Patel, K. D.; Solanki, G. K.

2016-01-01

Tungsten Di-Selenide belongs to the family of TMDCs showing their potential applications in the fields of Optoelectronics and PEC solar cells. Here in the present investigation single crystals of WSe_2 were grown by Direct Vapour Transport Technique in a dual zone furnace having temperature difference of 50 K between the two zones. These single crystals were characterized by EDAX which confirms the stiochiometry of the grown crystals. Surface topography of the crystal was studied by optical micrograph showing the left handed spirals on the surface of WSe_2 crystals. Single crystalline nature of the crystals was confirmed by SAED.

MR findings of facial nerve on oblique sagittal MRI using TMJ surface coil: normal vs peripheral facial nerve palsy

International Nuclear Information System (INIS)

Park, Yong Ok; Lee, Myeong Jun; Lee, Chang Joon; Yoo, Jeong Hyun

2000-01-01

To evaluate the findings of normal facial nerve, as seen on oblique sagittal MRI using a TMJ (temporomandibular joint) surface coil, and then to evaluate abnormal findings of peripheral facial nerve palsy. We retrospectively reviewed the MR findings of 20 patients with peripheral facial palsy and 50 normal facial nerves of 36 patients without facial palsy. All underwent oblique sagittal MRI using a T MJ surface coil. We analyzed the course, signal intensity, thickness, location, and degree of enhancement of the facial nerve. According to the angle made by the proximal parotid segment on the axis of the mastoid segment, course was classified as anterior angulation (obtuse and acute, or buckling), straight and posterior angulation. Among 50 normal facial nerves, 24 (48%) were straight, and 23 (46%) demonstrated anterior angulation; 34 (68%) showed iso signal intensity on T1W1. In the group of patients, course on the affected side was either straight (40%) or showed anterior angulation (55%), and signal intensity in 80% of cases was isointense. These findings were similar to those in the normal group, but in patients with post-traumatic or post-operative facial palsy, buckling, of course, appeared. In 12 of 18 facial palsy cases (66.6%) in which contrast materials were administered, a normal facial nerve of the opposite facial canal showed mild enhancement on more than one segment, but on the affected side the facial nerve showed diffuse enhancement in all 14 patients with acute facial palsy. Eleven of these (79%) showed fair or marked enhancement on more than one segment, and in 12 (86%), mild enhancement of the proximal parotid segment was noted. Four of six chronic facial palsy cases (66.6%) showed atrophy of the facial nerve. When oblique sagittal MR images are obtained using a TMJ surface coil, enhancement of the proximal parotid segment of the facial nerve and fair or marked enhancement of at least one segment within the facial canal always suggests pathology of

Physical concepts of materials for novel optoelectronic device applications II: Device physics and applications; Proceedings of the Meeting, Aachen, Federal Republic of Germany, Oct. 28-Nov. 2, 1990

International Nuclear Information System (INIS)

Razeghi, M.

1991-01-01

The present conference on physical concepts for materials for novel optoelectronic device applications encompasses the device physics and applications including visible, IR, and far-IR sources, optoelectronic quantum devices, the physics and applications of high-Tc superconducting materials, photodetectors and modulators, and the electronic properties of heterostructures. Other issues addressed include semiconductor waveguides for optical switching, wide band-gap semiconductors, Si and Si-Ge alloys, transport phenomena in heterostructures and quantum wells, optoelectronic integrated circuits, nonlinear optical phenomena in bulk and multiple quantum wells, and optoelectronic technologies for microwave applications. Also examined are optical computing, current transport in charge-injection devices, thin films of YBaCuO for electronic applications, indirect stimulated emission at room temperature in the visible range, and a laser with active-element rectangular geometry

Electronic Processes at Organic−Organic Interfaces: Insight from Modeling and Implications for Opto-electronic Devices †

KAUST Repository

Beljonne, David; Cornil, Jérôme; Muccioli, Luca; Zannoni, Claudio; Brédas, Jean-Luc; Castet, Frédéric

2011-01-01

We report on the recent progress achieved in modeling the electronic processes that take place at interfaces between π-conjugated materials in organic opto-electronic devices. First, we provide a critical overview of the current computational

Structural phase transition and opto-electronic properties of NaZnAs

Energy Technology Data Exchange (ETDEWEB)

Djied, A.; Seddik, T.; Merabiha, O. [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 (Algeria); Murtaza, G. [Materials Modeling Lab, Department of Physics, Islamia College University, Peshawar (Pakistan); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 (Algeria); Ahmed, R., E-mail: rashidahmed@utm.my [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, UTM Skudai, 81310 Johor (Malaysia); Bin-Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Uğur, Ş. [Department of Physics, Faculty of Sciences, Gazi University, 06500 Teknikokullar, Ankara (Turkey); Bouhemadou, A. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University Setif 1, 19000 Setif (Algeria)

2015-02-15

Highlights: • First competent characterizations of NaZnAs at the level of FP-LAPW+lo. • NaZnAs, a potential alternative candidate to III-V for photovoltaic applications. • NaZnAs, a cheaper and abundantly available direct band gap semiconductor. • Potential material for solar radiation absorber from infrared to ultraviolet. - Abstract: In this study, we predict the structural phase transitions as well as opto-electronic properties of the filled-tetrahedral (Nowotny-Juza) NaZnAs compound. Calculations employ the full potential (FP) linearized augmented plane wave (LAPW) plus local orbitals (lo) scheme. The exchange-correlation potential is treated within the generalized gradient approximation of Perdew-Burke and Ernzerhof (GGA-PBE). In addition, Tran and Blaha (TB) modified Becke-Johnson (mBJ) potential is also used to obtain more accurate optoelectronic properties. Geometry optimization is performed to obtain reliable total energies and other structural parameters for each NaZnAs phase. In our study, the sequence of the structural phase transition on compression is Cu{sub 2}Sb-type → β → α phase. NaZnAs is a direct (Γ-Γ) band gap semiconductor for all the structural phases. However, compared to PBE-GGA, the mBJ approximation reproduces better fundamental band gaps. Moreover, for insight into its potential for photovoltaic applications, different optical parameters are studied.

Structural phase transition and opto-electronic properties of NaZnAs

International Nuclear Information System (INIS)

Djied, A.; Seddik, T.; Merabiha, O.; Murtaza, G.; Khenata, R.; Ahmed, R.; Bin-Omran, S.; Uğur, Ş.; Bouhemadou, A.

2015-01-01

Highlights: • First competent characterizations of NaZnAs at the level of FP-LAPW+lo. • NaZnAs, a potential alternative candidate to III-V for photovoltaic applications. • NaZnAs, a cheaper and abundantly available direct band gap semiconductor. • Potential material for solar radiation absorber from infrared to ultraviolet. - Abstract: In this study, we predict the structural phase transitions as well as opto-electronic properties of the filled-tetrahedral (Nowotny-Juza) NaZnAs compound. Calculations employ the full potential (FP) linearized augmented plane wave (LAPW) plus local orbitals (lo) scheme. The exchange-correlation potential is treated within the generalized gradient approximation of Perdew-Burke and Ernzerhof (GGA-PBE). In addition, Tran and Blaha (TB) modified Becke-Johnson (mBJ) potential is also used to obtain more accurate optoelectronic properties. Geometry optimization is performed to obtain reliable total energies and other structural parameters for each NaZnAs phase. In our study, the sequence of the structural phase transition on compression is Cu 2 Sb-type → β → α phase. NaZnAs is a direct (Γ-Γ) band gap semiconductor for all the structural phases. However, compared to PBE-GGA, the mBJ approximation reproduces better fundamental band gaps. Moreover, for insight into its potential for photovoltaic applications, different optical parameters are studied

The effects of surface stripping ZnO nanorods with argon bombardment

International Nuclear Information System (INIS)

Barnett, Chris J; Kryvchenkova, Olga; Maffeis, Thierry G G; Cobley, Richard J; Smith, Nathan A; Kelleher, Liam

2015-01-01

ZnO nanorods are used in devices including field effects transistors, piezoelectric transducers, optoelectronics and gas sensors. However, for efficient and reproducible device operation and contact behaviour, surface contaminants must be removed or controlled. Here we use low doses of argon bombardment to remove surface contamination and make reproducible lower resistance contacts. Higher doses strip the surface of the nanorods allowing intrinsic surface measurements through a cross section of the material. Photoluminescence finds that the defect distribution is higher at the near-surface, falling away in to the bulk. Contacts to the n-type defect-rich surface are near-Ohmic, whereas stripping away the surface layers allows more rectifying Schottky contacts to be formed. The ability to select the contact type to ZnO nanorods offers a new way to customize device behaviour. (paper)

Facile fabrication of boron nitride nanosheets-amorphous carbon hybrid film for optoelectronic applications

KAUST Repository

Wan, Shanhong

2015-01-01

A novel boron nitride nanosheets (BNNSs)-amorphous carbon (a-C) hybrid film has been deposited successfully on silicon substrates by simultaneous electrochemical deposition, and showed a good integrity of this B-C-N composite film by the interfacial bonding. This synthesis can potentially provide the facile control of the B-C-N composite film for the potential optoelectronic devices. This journal is

Measuring the Valence of Nanocrystal Surfaces

Energy Technology Data Exchange (ETDEWEB)

Owen, Jonathan Scharle [Columbia Univ., New York, NY (United States)

2016-11-30

The goal of this project is to understand and control the interplay between nanocrystal stoichiometry, surface ligand binding and exchange, and the optoelectronic properties of semiconductor nanocrystals in solution and in thin solid films. We pursued three research directions with this goal in mind: 1) We characterized nanocrystal stoichiometry and its influence on the binding of L-type and X-type ligands, including the thermodynamics of binding and the kinetics of ligand exchange. 2) We developed a quantitative understanding of the relationship between surface ligand passivation and photoluminescence quantum yield. 3) We developed methods to replace the organic ligands on the nanocrystal with halide ligands and controllably deposit these nanocrystals into thin films, where electrical measurements were used to investigate the electrical transport and internanocrystal electronic coupling.

Study on optoelectronic properties of Spiro-CN for developing an efficient OLED

Science.gov (United States)

Mishra, Ashok Kumar

2018-05-01

There are a class of organic molecules and polymers which exhibit semiconductor behavior because of nearly free conjugate π-electrons. Hopping of these electrons in molecules forms different excited singlet and triplet states named as excitons. Some of these organic molecules can be set to emit photons by triplet-singlet excitonic transition via a process called Thermally Activated Delayed Fluorescence (TADF) which is exploited for designing the Organic Light Emitting diode (OLED.) Spiro-CN (spirobifluorene skeletons) Spiro is one of these reported noble metal-free TADF molecules which offers unique optical and electronic properties arising from the efficient transition and reverse intersystem crossing between the lowest singlet (S) and triplet (T) excited states. Its ability to harvest triplet excitons for fluorescence through facilitated reverse intersystem crossing (T→S) could directly impact their properties and performances, which is attractive for a wide variety of low-cost optoelectronic device. In the present study, the Spiro-CN compounds have been taken up for the investigation of various optoelectronic properties including the thermally activated delayed fluorescence (TADF) by using the Koopmans Method and Density Functional Theory. The present study discusses the utility of the Spiro-CN organic semiconductor as a suitable TADF material essential for developing an efficient Organic Light Emitting Diode (OLED).

Van der Waals epitaxial growth and optoelectronics of large-scale WSe2/SnS2 vertical bilayer p-n junctions.

Science.gov (United States)

Yang, Tiefeng; Zheng, Biyuan; Wang, Zhen; Xu, Tao; Pan, Chen; Zou, Juan; Zhang, Xuehong; Qi, Zhaoyang; Liu, Hongjun; Feng, Yexin; Hu, Weida; Miao, Feng; Sun, Litao; Duan, Xiangfeng; Pan, Anlian

2017-12-04

High-quality two-dimensional atomic layered p-n heterostructures are essential for high-performance integrated optoelectronics. The studies to date have been largely limited to exfoliated and restacked flakes, and the controlled growth of such heterostructures remains a significant challenge. Here we report the direct van der Waals epitaxial growth of large-scale WSe 2 /SnS 2 vertical bilayer p-n junctions on SiO 2 /Si substrates, with the lateral sizes reaching up to millimeter scale. Multi-electrode field-effect transistors have been integrated on a single heterostructure bilayer. Electrical transport measurements indicate that the field-effect transistors of the junction show an ultra-low off-state leakage current of 10 -14 A and a highest on-off ratio of up to 10 7 . Optoelectronic characterizations show prominent photoresponse, with a fast response time of 500 μs, faster than all the directly grown vertical 2D heterostructures. The direct growth of high-quality van der Waals junctions marks an important step toward high-performance integrated optoelectronic devices and systems.

Conducting polymers, buckminsterfullerenes, and carbon nanotubes: optoelectronic materials based on architectural diversity of the π-conjugated structure

International Nuclear Information System (INIS)

Dai, L.

2001-01-01

Recent discovery of superconductivity in self assembled poly(3-hexylthiophene) two-dimensional conjugated sheets indicates the possible applications of plastics even in superconducting optoelectronic devices. Just as the discovery of C 60 has created an entirely new branch of carbon chemistry, the subsequent discovery of carbon nanotubes by lijima in 1991 opened up a new era in material science and nanotechnology. These elongated nanotubes consist of carbon hexagons arranged in a concentric manner with both ends normally capped by fullerene-like structures containing pentagons. Having a conjugated all-carbon structure with unusual molecular symmetries, fullerenes and carbon nanotubes also show interesting electronic, photonic, magnetic and mechanical properties, attractive for various applications, including optical limiters, photovoltaic cells and field emitting displays. For most of the above applications, it is highly desirable to prepare ordered/micropatterned conducting polymers, fullerenes, and carbon nanotubes. Although the microfabrication of conducting polymers has been an active research area for some years, it is a very recent development for fullerenes and carbon nanotubes. Recently, we doped polyaniline (PANI) with a hydrogensulfated fullerenol derivative containing multiple -OSO 3 H groups (i.e. C 60 (OH) 6 (OSO 3 H) 6 ) to produce three-dimensional PANI conductors with a room-temperature conductivity of up to 100 S cm -1 . This value of conductivity is about six orders of magnitude higher than the typical value for C 60 doped conducting polymers. Later, in collaboration with Wan's group at the Chinese Academy of Sciences, we have also synthesized PANI nanotubes via a self assembled C 60 (OH) 6 (OSO 3 H) 6 supramolecular template using (NH 4 ) 2 S 2 O 8 as an oxidant. These results, together with the more recent discovery of a hollow sphere, self assembled by the potassium salt of pentaphenyl fullerene (Ph 5 C 60 K) in water, clearly indicate that

A hybrid lightwave transmission system based on light injection/optoelectronic feedback techniques and fiber-VLLC integration

International Nuclear Information System (INIS)

Tsai, Wen-Shing; Lu, Hai-Han; Li, Chung-Yi; Chen, Bo-Rui; Lin, Hung-Hsien; Lin, Dai-Hua

2016-01-01

A hybrid lightwave transmission system based on light injection/optoelectronic feedback techniques and fiber-visible laser light communication (VLLC) integration is proposed and experimentally demonstrated. To be the first one of its kind in employing light injection and optoelectronic feedback techniques in a fiber-VLLC integration lightwave transmission system, the light is successfully directly modulated with Community Access Television (CATV), 16-QAM, and 16-QAM-OFDM signals. Over a 40 km SMF and a 10 m free-space VLLC transport, good performances of carrier-to-noise ratio (CNR)/composite second-order (CSO)/composite triple-beat (CTB)/bit error rate (BER) are achieved for CATV/16-QAM/16-QAM-OFDM signals transmission. Such a hybrid lightwave transmission system would be very useful since it can provide broadband integrated services including CATV, Internet, and telecommunication services over both distribute fiber and in-building networks. (letter)

Delay dynamics of neuromorphic optoelectronic nanoscale resonators: Perspectives and applications

Science.gov (United States)

Romeira, Bruno; Figueiredo, José M. L.; Javaloyes, Julien

2017-11-01

With the recent exponential growth of applications using artificial intelligence (AI), the development of efficient and ultrafast brain-like (neuromorphic) systems is crucial for future information and communication technologies. While the implementation of AI systems using computer algorithms of neural networks is emerging rapidly, scientists are just taking the very first steps in the development of the hardware elements of an artificial brain, specifically neuromorphic microchips. In this review article, we present the current state of the art of neuromorphic photonic circuits based on solid-state optoelectronic oscillators formed by nanoscale double barrier quantum well resonant tunneling diodes. We address, both experimentally and theoretically, the key dynamic properties of recently developed artificial solid-state neuron microchips with delayed perturbations and describe their role in the study of neural activity and regenerative memory. This review covers our recent research work on excitable and delay dynamic characteristics of both single and autaptic (delayed) artificial neurons including all-or-none response, spike-based data encoding, storage, signal regeneration and signal healing. Furthermore, the neural responses of these neuromorphic microchips display all the signatures of extended spatio-temporal localized structures (LSs) of light, which are reviewed here in detail. By taking advantage of the dissipative nature of LSs, we demonstrate potential applications in optical data reconfiguration and clock and timing at high-speeds and with short transients. The results reviewed in this article are a key enabler for the development of high-performance optoelectronic devices in future high-speed brain-inspired optical memories and neuromorphic computing.

Recent trend in graphene for optoelectronics

International Nuclear Information System (INIS)

Chen, Yu-Bin; Liu, John S.; Lin Pang

2013-01-01

This study analyzes the scientific knowledge diffusion paths of graphene for optoelectronics (GFO), where graphene offers wide applications due to its thinness, high conductivity, excellent transparency, chemical stability, robustness, and flexibility. Our investigation is based on the main path analysis which establishes the citation links among the literature data in order to trace the significant sequence of knowledge development in this emerging field. We identify the main development paths of GFO up to the year 2012, along which a series of influential papers in this field are identified. The main path graph shows that knowledge diffusion occurs in key subareas, including reduced graphene oxide, chemical vapor deposition, and exfoliation techniques, which are developed for the preparation and applications of GFO. The applications cover solar cells, laser devices, sensing devices, and LCD. In addition, the main theme of GFO research evolves in sequence from small-graphene-sample preparation, to large-scale film growth, and onto prototype device fabrication. This evolution reflects a strong industrial demand for a new transparent–conductive film technology.

Reproducibility and day time bias correction of optoelectronic leg volumetry: a prospective cohort study.

Science.gov (United States)

Engelberger, Rolf P; Blazek, Claudia; Amsler, Felix; Keo, Hong H; Baumann, Frédéric; Blättler, Werner; Baumgartner, Iris; Willenberg, Torsten

2011-10-05

Leg edema is a common manifestation of various underlying pathologies. Reliable measurement tools are required to quantify edema and monitor therapeutic interventions. Aim of the present work was to investigate the reproducibility of optoelectronic leg volumetry over 3 weeks' time period and to eliminate daytime related within-individual variability. Optoelectronic leg volumetry was performed in 63 hairdressers (mean age 45 ± 16 years, 85.7% female) in standing position twice within a minute for each leg and repeated after 3 weeks. Both lower leg (legBD) and whole limb (limbBF) volumetry were analysed. Reproducibility was expressed as analytical and within-individual coefficients of variance (CVA, CVW), and as intra-class correlation coefficients (ICC). A total of 492 leg volume measurements were analysed. Both legBD and limbBF volumetry were highly reproducible with CVA of 0.5% and 0.7%, respectively. Within-individual reproducibility of legBD and limbBF volumetry over a three weeks' period was high (CVW 1.3% for both; ICC 0.99 for both). At both visits, the second measurement revealed a significantly higher volume compared to the first measurement with a mean increase of 7.3 ml ± 14.1 (0.33% ± 0.58%) for legBD and 30.1 ml ± 48.5 ml (0.52% ± 0.79%) for limbBF volume. A significant linear correlation between absolute and relative leg volume differences and the difference of exact day time of measurement between the two study visits was found (P correction formula permitted further improvement of CVW. Leg volume changes can be reliably assessed by optoelectronic leg volumetry at a single time point and over a 3 weeks' time period. However, volumetry results are biased by orthostatic and daytime-related volume changes. The bias for day-time related volume changes can be minimized by a time-correction formula.

Reproducibility and day time bias correction of optoelectronic leg volumetry: a prospective cohort study

Directory of Open Access Journals (Sweden)

Baumgartner Iris

2011-10-01

Full Text Available Abstract Background Leg edema is a common manifestation of various underlying pathologies. Reliable measurement tools are required to quantify edema and monitor therapeutic interventions. Aim of the present work was to investigate the reproducibility of optoelectronic leg volumetry over 3 weeks' time period and to eliminate daytime related within-individual variability. Methods Optoelectronic leg volumetry was performed in 63 hairdressers (mean age 45 ± 16 years, 85.7% female in standing position twice within a minute for each leg and repeated after 3 weeks. Both lower leg (legBD and whole limb (limbBF volumetry were analysed. Reproducibility was expressed as analytical and within-individual coefficients of variance (CVA, CVW, and as intra-class correlation coefficients (ICC. Results A total of 492 leg volume measurements were analysed. Both legBD and limbBF volumetry were highly reproducible with CVA of 0.5% and 0.7%, respectively. Within-individual reproducibility of legBD and limbBF volumetry over a three weeks' period was high (CVW 1.3% for both; ICC 0.99 for both. At both visits, the second measurement revealed a significantly higher volume compared to the first measurement with a mean increase of 7.3 ml ± 14.1 (0.33% ± 0.58% for legBD and 30.1 ml ± 48.5 ml (0.52% ± 0.79% for limbBF volume. A significant linear correlation between absolute and relative leg volume differences and the difference of exact day time of measurement between the two study visits was found (P W. Conclusions Leg volume changes can be reliably assessed by optoelectronic leg volumetry at a single time point and over a 3 weeks' time period. However, volumetry results are biased by orthostatic and daytime-related volume changes. The bias for day-time related volume changes can be minimized by a time-correction formula.

Ultrafast Phase Comparator for Phase-Locked Loop-Based Optoelectronic Clock Recovery Systems

DEFF Research Database (Denmark)

Gomez-Agis, F.; Oxenløwe, Leif Katsuo; Kurimura, S.

2009-01-01

The authors report on a novel application of a chi((2)) nonlinear optical device as an ultrafast phase comparator, an essential element that allows an optoelectronic phase-locked loop to perform clock recovery of ultrahigh-speed optical time-division multiplexed (OTDM) signals. Particular interest...... is devoted to a quasi-phase-matching adhered-ridge-waveguide periodically poled lithium niobate (PPLN) device, which shows a sufficient high temporal resolution to resolve a 640 Gbits OTDM signal....

Simultaneous dual-functioning InGaN/GaN multiple-quantum-well diode for transferrable optoelectronics

Science.gov (United States)

Shi, Zheng; Yuan, Jialei; Zhang, Shuai; Liu, Yuhuai; Wang, Yongjin

2017-10-01

We propose a wafer-level procedure for the fabrication of 1.5-mm-diameter dual functioning InGaN/GaN multiple-quantum-well (MQW) diodes on a GaN-on-silicon platform for transferrable optoelectronics. Nitride semiconductor materials are grown on (111) silicon substrates with intermediate Al-composition step-graded buffer layers, and membrane-type MQW-diode architectures are obtained by a combination of silicon removal and III-nitride film backside thinning. Suspended MQW-diodes are directly transferred from silicon to foreign substrates such as metal, glass and polyethylene terephthalate by mechanically breaking the support beams. The transferred MQW-diodes display strong electroluminescence under current injection and photodetection under light irradiation. Interestingly, they demonstrate a simultaneous light-emitting light-detecting function, endowing the 1.5-mm-diameter MQW-diode with the capability of producing transferrable optoelectronics for adjustable displays, wearable optical sensors, multifunctional energy harvesting, flexible light communication and monolithic photonic circuit.

The relationship between past caries experience and tooth color determined by an opto-electronic method.

Science.gov (United States)

Kerosuo, E; Kolehmainen, L

1982-01-01

The susceptibility of a tooth to dental caries has been proposed to depend on tooth color. So far there has, however, been no reliable method for tooth color determination. The aims of this study were to evaluate the reliability of an opto-electronic method and to examine the relationship between tooth color and past caries experience. The color of upper right central incisors of 64 school-children was determined using an opto-electronic tri-stimulus color comparator. The intra- and interexaminer reliability of the method was evaluated in vitro and in vivo being 85% and 83%, respectively. To assess the past caries experience the DMFS-index was calculated. Oral hygiene and dietary habits were also assessed. No significant difference in DMFS scores was obtained between the 'white teeth' group and the 'yellow teeth' group. The conclusion is, that the practical importance of possible colorrelated differences in caries resistance is negligible due to the multifaceted nature of dental caries.

RIR-MAPLE deposition of conjugated polymers and hybrid nanocomposites for application to optoelectronic devices

International Nuclear Information System (INIS)

Stiff-Roberts, Adrienne D.; Pate, Ryan; McCormick, Ryan; Lantz, Kevin R.

2012-01-01

Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) is a variation of pulsed laser deposition that is useful for organic-based thin films because it reduces material degradation by selective absorption of infrared radiation in the host matrix. A unique emulsion-based RIR-MAPLE approach has been developed that reduces substrate exposure to solvents and provides controlled and repeatable organic thin film deposition. In order to establish emulsion-based RIR-MAPLE as a preferred deposition technique for conjugated polymer or hybrid nanocomposite optoelectronic devices, studies have been conducted to demonstrate the value added by the approach in comparison to traditional solution-based deposition techniques, and this work will be reviewed. The control of hybrid nanocomposite thin film deposition, and the photoconductivity in such materials deposited using emulsion-based RIR-MAPLE, will also be reviewed. The overall result of these studies is the demonstration of emulsion-based RIR-MAPLE as a viable option for the fabrication of conjugated polymer and hybrid nanocomposite optoelectronic devices that could yield improved device performance.

Surface morphology of active normal faults in hard rock: Implications for the mechanics of the Asal Rift, Djibouti

Science.gov (United States)

Pinzuti, Paul; Mignan, Arnaud; King, Geoffrey C. P.

2010-10-01

Tectonic-stretching models have been previously proposed to explain the process of continental break-up through the example of the Asal Rift, Djibouti, one of the few places where the early stages of seafloor spreading can be observed. In these models, deformation is distributed starting at the base of a shallow seismogenic zone, in which sub-vertical normal faults are responsible for subsidence whereas cracks accommodate extension. Alternative models suggest that extension results from localised magma intrusion, with normal faults accommodating extension and subsidence only above the maximum reach of the magma column. In these magmatic rifting models, or so-called magmatic intrusion models, normal faults have dips of 45-55° and root into dikes. Vertical profiles of normal fault scarps from levelling campaign in the Asal Rift, where normal faults seem sub-vertical at surface level, have been analysed to discuss the creation and evolution of normal faults in massive fractured rocks (basalt lava flows), using mechanical and kinematics concepts. We show that the studied normal fault planes actually have an average dip ranging between 45° and 65° and are characterised by an irregular stepped form. We suggest that these normal fault scarps correspond to sub-vertical en echelon structures, and that, at greater depth, these scarps combine and give birth to dipping normal faults. The results of our analysis are compatible with the magmatic intrusion models instead of tectonic-stretching models. The geometry of faulting between the Fieale volcano and Lake Asal in the Asal Rift can be simply related to the depth of diking, which in turn can be related to magma supply. This new view supports the magmatic intrusion model of early stages of continental breaking.

Surface tension of normal and heavy water

International Nuclear Information System (INIS)

Straub, J.; Rosner, N.; Grigull, V.

1980-01-01

A Skeleton Table and simple interpolation equation for the surface tension of light water was developed by the Working Group III of the International Association for the Properties of Steam and is recommended as an International Standard. The Skeleton Table is based on all known measurements of the surface tension and individual data were weighted corresponding to the accuracy of the measurements. The form of the interpolation equation is based on a physical concept. It represents an extension of van der Waals-equation, where the exponent conforms to the 'Scaling Laws'. In addition for application purposes simple relations for the Laplace-coefficient and for the density difference between the liquid and gaseous phases of light water are given. The same form of interpolation equation for the surface tension can be used for heavy water, for which the coefficients are given. However, this equation is based only on a single set of data. (orig.) [de

Ultrahigh resolution long range surface plasmon-based sensor

Czech Academy of Sciences Publication Activity Database

Slavík, Radan; Homola, Jiří

2007-01-01

Roč. 123, č. 1 (2007), s. 10-12 ISSN 0925-4005 R&D Projects: GA ČR GP202/04/P141; GA ČR GA203/02/1326; GA ČR(CZ) GA303/03/0249 Grant - others:European Commission(XE) QLK4-CT-2002-02323; US FDA (US) FD-U-002250 Institutional research plan: CEZ:AV0Z20670512 Keywords : surface plasmon resonance * refractive index Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.934, year: 2007

A 2-10 GHz GaAs MMIC opto-electronic phase detector for optical microwave signal generators

DEFF Research Database (Denmark)

Bruun, Marlene; Gliese, Ulrik Bo; Petersen, Anders Kongstad

1994-01-01

Optical transmission of microwave signals becomes increasingly important. Techniques using beat between optical carriers of semiconductor lasers are promising if efficient optical phase locked loops are realized. A highly efficient GaAs MMIC optoelectronic phase detector for a 2-10 GHz OPLL...

Resonant infrared laser deposition of polymer-nanocomposite materials for optoelectronic applications

Science.gov (United States)

Park, Hee K.; Schriver, Kenneth E.; Haglund, Richard F.

2011-11-01

Polymers find a number of potentially useful applications in optoelectronic devices. These include both active layers, such as light-emitting polymers and hole-transport layers, and passive layers, such as polymer barrier coatings and light-management films. This paper reports the experimental results for polymer films deposited by resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) and resonant infrared pulsed laser deposition (RIR-PLD) for commercial optoelectronic device applications. In particular, light-management films, such as anti-reflection coatings, require refractive-index engineering of a material. However, refractive indices of polymers fall within a relatively narrow range, leading to major efforts to develop both low- and high-refractive-index polymers. Polymer nanocomposites can expand the range of refractive indices by incorporating low- or high-refractive-index nanoscale materials. RIR-MAPLE is an excellent technique for depositing polymer-nanocomposite films in multilayer structures, which are essential to light-management coatings. In this paper, we report our efforts to engineer the refractive index of a barrier polymer by combining RIR-MAPLE of nanomaterials (for example, high refractive-index TiO2 nanoparticles) and RIR-PLD of host polymer. In addition, we report on the properties of organic and polymer films deposited by RIR-MAPLE and/or RIR-PLD, such as Alq3 [tris(8-hydroxyquinoline) aluminum] and PEDOT:PSS [poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)]. Finally, the challenges and potential for commercializing RIR-MAPLE/PLD, such as industrial scale-up issues, are discussed.

Controlling surface plasmon polaritons by a static and/or time-dependent external magnetic field

Czech Academy of Sciences Publication Activity Database

Kuzmiak, Vladimír; Eyderman, Sergey; Vanwolleghem, M.

2012-01-01

Roč. 86, č. 4 (2012), s. 045403 ISSN 1098-0121 R&D Projects: GA ČR(CZ) GAP205/10/0046 Grant - others:GA MŠk(CZ) MP0702 Institutional support: RVO:67985882 Keywords : one-way electromegnetic waveguide * magneto-optic photonic crystal * surface plasmon polarirton Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.767, year: 2012

Controlling surface plasmon polaritons by a static and/or time-dependent external magnetic field

Czech Academy of Sciences Publication Activity Database

Kuzmiak, Vladimír; Eyderman, Sergey; Vanwolleghem, M.

2012-01-01

Roč. 86, č. 4 (2012), s. 045403 ISSN 1098-0121 R&D Projects: GA ČR(CZ) GAP205/10/0046 Grant - others:GA MŠk(CZ) MP0702 Institutional support: RVO:67985882 Keywords : one-way electromegnetic waveguide * magneto- optic photonic crystal * surface plasmon polarirton Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.767, year: 2012

Growth and Characterisation of GaAs/AlGaAs Core-shell Nanowires for Optoelectronic Device Applications

Science.gov (United States)

Jiang, Nian

III-V semiconductor nanowires have been investigated as key components for future electronic and optoelectronic devices and systems due to their direct band gap and high electron mobility. Amongst the III-V semiconductors, the planar GaAs material system has been extensively studied and used in industries. Accordingly, GaAs nanowires are the prime candidates for nano-scale devices. However, the electronic performance of GaAs nanowires has yet to match that of state-of-the-art planar GaAs devices. The present deficiency of GaAs nanowires is typically attributed to the large surface-to- volume ratio and the tendency for non-radiative recombination centres to form at the surface. The favoured solution of this problem is by coating GaAs nanowires with AlGaAs shells, which replaces the GaAs surface with GaAs/AlGaAs interface. This thesis presents a systematic study of GaAs/AlGaAs core-shell nanowires grown by metal organic chemical vapour deposition (MOCVD), including understanding the growth, and characterisation of their structural and optical properties. The structures of the nanowires were mainly studied by scanning electron microscopy and transmis- sion electron microscopy (TEM). A procedure of microtomy was developed to prepare the cross-sectional samples for the TEM studies. The optical properties were charac- terised by photoluminescence (PL) spectroscopy. Carrier lifetimes were measured by time-resolved PL. The growth of AlGaAs shell was optimised to obtain the best optical properties, e.g. the strongest PL emission and the longest minority carrier lifetimes. (Abstract shortened by ProQuest.).

Implantable optoelectronic probes for in vivo optogenetics

Science.gov (United States)

Iseri, Ege; Kuzum, Duygu

2017-06-01

More than a decade has passed since optics and genetics came together and lead to the emerging technologies of optogenetics. The advent of light-sensitive opsins made it possible to optically trigger the neurons into activation or inhibition by using visible light. The importance of spatiotemporally isolating a segment of a neural network and controlling nervous signaling in a precise manner has driven neuroscience researchers and engineers to invest great efforts in designing high precision in vivo implantable devices. These efforts have focused on delivery of sufficient power to deep brain regions, while monitoring neural activity with high resolution and fidelity. In this review, we report the progress made in the field of hybrid optoelectronic neural interfaces that combine optical stimulation with electrophysiological recordings. Different approaches that incorporate optical or electrical components on implantable devices are discussed in detail. Advantages of various different designs as well as practical and fundamental limitations are summarized to illuminate the future of neurotechnology development.

Radiation-hard Optoelectronics for LHC detector upgrades.

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00375195; Newbold, Dave

A series of upgrades foreseen for the LHC over the next decade will allow the proton-proton collisions to reach the design center of mass energy of 14 TeV and increase the luminosity to five times (High Luminosity-LHC) the design luminosity by 2027. Radiation-tolerant high-speed optical data transmission links will continue to play an important role in the infrastructure of particle physics experiments over the next decade. A new generation of optoelectronics that meet the increased performance and radiation tolerance limits imposed by the increase in the intensity of the collisions at the interaction points are currently being developed. This thesis focuses on the development of a general purpose bi-directional 5 Gb/s radiation tolerant optical transceiver, the Versatile Transceiver (VTRx), for use by the LHC experiments over the next five years, and on exploring the radiation-tolerance of state-of-the art silicon photonics modulators for HL-LHC data transmission applications. The compliance of the VTRx ...

Characterization of Semiconductor Nanocrystal Assemblies as Components of Optoelectronic Devices

Science.gov (United States)

Malfavon-Ochoa, Mario

dispersions of core and core/shell NCs will be shown to produce close packed assemblies of NCs forming near-wavelength luminescent superstructures separated in space. We show the dominant contribution of a two-monolayer thick sharp interface CdS shell to the diffraction efficiency, and necessarily the refractive index, of the NCs, independent of core size. Utilization of these gratings as in-coupling elements at various positions within a device architecture are also examined. These new observations were achieved by unprecedented control of NC architecture during dispersion processing, while maintaining high luminescence, made possible by optimized NC surface passivation. These studies enable the formation of new LED architectures, and new optoelectronic devices based on angle resolved, monochromatic fluorescence from diffraction gratings prepared from simple solution processing approaches. Further, the novel observation of angle amplified interfering fluorescence from these features is argued to be a result of long range radiative coupling and superradiance enabled by the monodispersity and high-quality NC surface passivation described herein.

Synthesis of In0.1Ga0.9N/GaN structures grown by MOCVD and MBE for high speed optoelectronics

KAUST Repository

Alshehri, Bandar; Dogheche, Karim; Belahsene, Sofiane; Janjua, Bilal; Ramdane, Abderrahim; Patriarche, Gilles; Ng, Tien Khee; S-Ooi, Boon; Decoster, Didier; Dogheche, Elhadj

2016-01-01

In this work, we report a comparative investigation of InxGa1-xN (SL) and InxGa1-xN/GaN (MQW) structures with an indium content equivalent to x=10%. Both structures are grown on (0001) sapphire substrates using MOCVD and MBE growth techniques. Optical properties are evaluated for samples using PL characteristics. Critical differences between the resulting epitaxy are observed. Microstructures have been assessed in terms of crystalline quality, density of dislocations and surface morphology. We have focused our study towards the fabrication of vertical PIN photodiodes. The technological process has been optimized as a function of the material structure. From the optical and electrical characteristics, this study demonstrates the benefit of InGaN/GaN MQW grown by MOCVD in comparison with MBE for high speed optoelectronic applications.

Synthesis of In0.1Ga0.9N/GaN structures grown by MOCVD and MBE for high speed optoelectronics

KAUST Repository

Alshehri, Bandar

2016-06-07

In this work, we report a comparative investigation of InxGa1-xN (SL) and InxGa1-xN/GaN (MQW) structures with an indium content equivalent to x=10%. Both structures are grown on (0001) sapphire substrates using MOCVD and MBE growth techniques. Optical properties are evaluated for samples using PL characteristics. Critical differences between the resulting epitaxy are observed. Microstructures have been assessed in terms of crystalline quality, density of dislocations and surface morphology. We have focused our study towards the fabrication of vertical PIN photodiodes. The technological process has been optimized as a function of the material structure. From the optical and electrical characteristics, this study demonstrates the benefit of InGaN/GaN MQW grown by MOCVD in comparison with MBE for high speed optoelectronic applications.

Optoelectronic link for analog signals from solid state detectors in high energy physics

International Nuclear Information System (INIS)

Manfredi, P.F.; Speziali, V.

1983-01-01

An optoelectric link has been made to transmit analog signals over a long distance between the beam area and the remote-end data acquisition instrumentation in high energy experiments. The optoelectronic link is intended for silicon target applications and it is designed to work on the signals at the output of a low noise amplifier system. Its advantages over a conventional galvanic connection as well as its limitations are discussed. (orig.)

Performance evaluation of sea surface simulation methods for target detection

Science.gov (United States)

Xia, Renjie; Wu, Xin; Yang, Chen; Han, Yiping; Zhang, Jianqi

2017-11-01

With the fast development of sea surface target detection by optoelectronic sensors, machine learning has been adopted to improve the detection performance. Many features can be learned from training images by machines automatically. However, field images of sea surface target are not sufficient as training data. 3D scene simulation is a promising method to address this problem. For ocean scene simulation, sea surface height field generation is the key point to achieve high fidelity. In this paper, two spectra-based height field generation methods are evaluated. Comparison between the linear superposition and linear filter method is made quantitatively with a statistical model. 3D ocean scene simulating results show the different features between the methods, which can give reference for synthesizing sea surface target images with different ocean conditions.

The Surface of Hybrid Perovskite Crystals: A Boon or Bane

KAUST Repository

Banavoth, Murali

2017-03-03

Hybrid perovskite single crystals have garnered tremendous research attention and are expected to be next-generation materials for high-efficiency photoactive devices. Therefore, it is fundamentally important to understand the 8 relationship between the optoelectronic properties of these materials and the marginally exploited surface chemistry in ambient air. For instance, a strong surface disorder, including hydration and ion migration, can possibly lead to extremely different optical and electronic properties at the surface compared to the bulk of the single crystal (SC). From this perspective, we evaluate the key variables that underlie the perovskite SC surface restructuring in ambient air and discuss their merits and limitations. In addition, a comprehensive picture of surface disordering, the remarkable change in the charge carrier dynamics and carrier mobility, surface hydration, and the effect of ion migration on the surface behavior will be discussed. Finally, surface passivation methods are highlighted to resolve or overcome the challenges for device integration.

Formation of patterned arrays of Au nanoparticles on SiC surface by template confined dewetting of normal and oblique deposited nanoscale films

Energy Technology Data Exchange (ETDEWEB)

Ruffino, F., E-mail: francesco.ruffino@ct.infn.it; Grimaldi, M.G.

2013-06-01

We report on the formation of patterned arrays of Au nanoparticles (NPs) on 6H SiC surface. To this end, we exploit the thermal-induced dewetting properties of a template confined deposited nanoscale Au film. In this approach, the Au surface pattern order, on the SiC substrate, is established by a template confined deposition using a micrometric template. Then, a dewetting process of the patterned Au film is induced by thermal processes. We compare the results, about the patterns formation, obtained for normal and oblique deposited Au films. We show that the normal and oblique depositions, through the same template, originate different patterns of the Au film. As a consequence of these different starting patterns, after the thermal processes, different patterns for the arrays of NPs originating from the dewetting mechanisms are obtained. For each fixed deposition angle α, the pattern evolution is analyzed, by scanning electron microscopy, as a function of the annealing time at 1173 K (900 °C). From these analyses, quantitative evaluations on the NPs size evolution are drawn. - Highlights: • Micrometric template-confined nanoscale gold films are deposited on silicon carbide. • The dewetting process of template-confined gold films on silicon carbide is studied. • Comparison of dewetting process of normal and oblique deposited gold films is drawn. • Patterned arrays of gold nanoparticles on silicon carbide surface are produced.

Formation of patterned arrays of Au nanoparticles on SiC surface by template confined dewetting of normal and oblique deposited nanoscale films

International Nuclear Information System (INIS)

Ruffino, F.; Grimaldi, M.G.

2013-01-01

We report on the formation of patterned arrays of Au nanoparticles (NPs) on 6H SiC surface. To this end, we exploit the thermal-induced dewetting properties of a template confined deposited nanoscale Au film. In this approach, the Au surface pattern order, on the SiC substrate, is established by a template confined deposition using a micrometric template. Then, a dewetting process of the patterned Au film is induced by thermal processes. We compare the results, about the patterns formation, obtained for normal and oblique deposited Au films. We show that the normal and oblique depositions, through the same template, originate different patterns of the Au film. As a consequence of these different starting patterns, after the thermal processes, different patterns for the arrays of NPs originating from the dewetting mechanisms are obtained. For each fixed deposition angle α, the pattern evolution is analyzed, by scanning electron microscopy, as a function of the annealing time at 1173 K (900 °C). From these analyses, quantitative evaluations on the NPs size evolution are drawn. - Highlights: • Micrometric template-confined nanoscale gold films are deposited on silicon carbide. • The dewetting process of template-confined gold films on silicon carbide is studied. • Comparison of dewetting process of normal and oblique deposited gold films is drawn. • Patterned arrays of gold nanoparticles on silicon carbide surface are produced

Ultrasonic off-normal imaging techniques for under sodium viewing

International Nuclear Information System (INIS)

Michaels, T.E.; Horn, J.E.

1979-01-01

Advanced imaging methods have been evaluated for the purpose of constructing images of objects from ultrasonic data. Feasibility of imaging surfaces which are off-normal to the sound beam has been established. Laboratory results are presented which show a complete image of a typical core component. Using the previous system developed for under sodium viewing (USV), only normal surfaces of this object could be imaged. Using advanced methods, surfaces up to 60 degrees off-normal have been imaged. Details of equipment and procedures used for this image construction are described. Additional work on high temperature transducers, electronics, and signal analysis is required in order to adapt the off-normal viewing process described here to an eventual USV application

Organic semiconductor photodiode based on indigo carmine/n-Si for optoelectronic applications

Science.gov (United States)

Ganesh, V.; Manthrammel, M. Aslam; Shkir, Mohd.; Yahia, I. S.; Zahran, H. Y.; Yakuphanoglu, F.; AlFaify, S.

2018-06-01

The fabrication of indigo carmine/n-Si photodiode has been done, and a robust dark and photocurrent-voltage ( I- V), capacitance vs. voltage ( C-V) and conductance vs. voltage ( G-V) studies were done over a wide range of applied voltage and frequencies. The surface morphology was assessed by atomic force microscope (AFM), and the grain size was measured to be about 66 nm. The reverse current increased with both increasing illumination intensity and bias potential, whereas the forward current increased exponentially with bias potential. The responsivity value was also calculated. Barrier height and ideality factor of diode were estimated through a log (I) vs log (V) plot, and obtained to be 0.843 and 4.75 eV, respectively. The Vbi values are found between 0.95 and 1.2V for frequencies ranging between 100 kHz and 1 MHz. The value of R s is found to be lower at higher frequencies which may be due to a certain distribution of localized interface states. A strong frequency and voltage dependency were observed for interface states density N ss in the present indigo carmine/n-Si photodiode, and this explained the observed capacitance and resistance variation with frequency. These results suggest that the fabricated diode has the potential to be applied in optoelectronic devices.

One-dimensional CuO nanowire: synthesis, electrical, and optoelectronic devices application

Science.gov (United States)

Luo, Lin-Bao; Wang, Xian-He; Xie, Chao; Li, Zhong-Jun; Lu, Rui; Yang, Xiao-Bao; Lu, Jian

2014-11-01

In this work, we presented a surface mechanical attrition treatment (SMAT)-assisted approach to the synthesis of one-dimensional copper oxide nanowires (CuO NWs) for nanodevices applications. The as-prepared CuO NWs have diameter and the length of 50 ~ 200 nm and 5 ~ 20 μm, respectively, with a preferential growth orientation along [1 [InlineEquation not available: see fulltext.] 0] direction. Interestingly, nanofield-effect transistor (nanoFET) based on individual CuO NW exhibited typical p-type electrical conduction, with a hole mobility of 0.129 cm2V-1 s-1 and hole concentration of 1.34 × 1018 cm-3, respectively. According to first-principle calculations, such a p-type electrical conduction behavior was related to the oxygen vacancies in CuO NWs. What is more, the CuO NW device was sensitive to visible light illumination with peak sensitivity at 600 nm. The responsitivity, conductive gain, and detectivity are estimated to be 2.0 × 102 A W-1, 3.95 × 102 and 6.38 × 1011 cm Hz1/2 W-1, respectively, which are better than the devices composed of other materials. Further study showed that nanophotodetectors assembled on flexible polyethylene terephthalate (PET) substrate can work under different bending conditions with good reproducibility. The totality of the above results suggests that the present CuO NWs are potential building blocks for assembling high-performance optoelectronic devices.

Unraveling the Role of Π - Conjugation in Thiophene Oligomers for Optoelectronic Properties by DFT/TDDFT Approach

Directory of Open Access Journals (Sweden)

Gajalakshmi

Full Text Available ABSTRACT Thiophene oligomer has been investigated using DFT/TDDFT calculations with an aim to check its suitability for opto electronic applications and also to analyse the influence of π-bridge. Our results revealed that thiophene oligomers have excellent π-conjugation throughout. FMO analysis give an estimate of band gap of thiophene oligomer and further revealed HOMO are localized on π - bridge, donor group and LUMO are localized on π - bridge and acceptor group. A TDDFT calculation has been performed to understand the absorption properties of them in gas phase and solvent phase. PCM calculations convey that absorption maxima show positive solvatochromism. Among the designed candidates, the one with more π - bridge show higher wavelength of absorption maxima and would be a choice for better optoelectronic materials. NBO analysis provides support for complete delocalization in these systems. It is interesting to note that oligomer with more π-bridge display an enhanced optoelectronic properties than with less π - bridge.

Ultrafast characterization of optoelectronic devices and systems

Science.gov (United States)

Zheng, Xuemei

The recent fast growth in high-speed electronics and optoelectronics has placed demanding requirements on testing tools. Electro-optic (EO) sampling is a well-established technique for characterization of high-speed electronic and optoelectronic devices and circuits. However, with the progress in device miniaturization, lower power consumption (smaller signal), and higher throughput (higher clock rate), EO sampling also needs to be updated, accordingly, towards better signal-to-noise ratio (SNR) and sensitivity, without speed sacrifice. In this thesis, a novel EO sampler with a single-crystal organic 4-dimethylamino-N-methy-4-stilbazolium tosylate (DAST) as the EO sensor is developed. The system exhibits sub-picosecond temporal resolution, sub-millivolt sensitivity, and a 10-fold improvement on SNR, compared with its LiTaO3 counterpart. The success is attributed to the very high EO coefficient, the very low dielectric constant, and the fast response, coming from the major contribution of the pi-electrons in DAST. With the advance of ultrafast laser technology, low-noise and compact femtosecond fiber lasers have come to maturation and become light-source options for ultrafast metrology systems. We have successfully integrated a femtosecond erbium-doped-fiber laser into an EO sampler, making the system compact and very reliable. The fact that EO sampling is essentially an impulse-response measurement process, requires integration of ultrashort (sub-picosecond) impulse generation network with the device under test. We have implemented a reliable lift-off and transfer technique in order to obtain epitaxial-quality freestanding low-temperature-grown GaAs (LT-GaAs) thin-film photo-switches, which can be integrated with many substrates. The photoresponse of our freestanding LT-GaAs devices was thoroughly characterized with the help of our EO sampler. As fast as 360 fs full-width-at-half-maximum (FWHM) and >1 V electrical pulses were obtained, with quantum efficiency

Development of the apparatus for measuring magnetic properties of electrical steel sheets in arbitrary directions under compressive stress normal to their surface

Science.gov (United States)

Maeda, Yoshitaka; Urata, Shinya; Nakai, Hideo; Takeuchi, Yuuya; Yun, Kyyoul; Yanase, Shunji; Okazaki, Yasuo

2017-05-01

In designing motors, one must grasp the magnetic properties of electrical steel sheets considering actual conditions in motors. Especially important is grasping the stress dependence of magnetic power loss. This paper describes a newly developed apparatus to measure two-dimensional (2-D) magnetic properties (properties under the arbitrary alternating and the rotating flux conditions) of electrical steel sheets under compressive stress normal to the sheet surface. The apparatus has a 2-D magnetic excitation circuit to generate magnetic fields in arbitrary directions in the evaluation area. It also has a pressing unit to apply compressive stress normal to the sheet surface. During measurement, it is important to apply uniform stress throughout the evaluation area. Therefore, we have developed a new flux density sensor using needle probe method. It is composed of thin copper foils sputtered on electrical steel sheets. By using this sensor, the stress can be applied to the surface of the specimen without influence of this sensor. This paper described the details of newly developed apparatus with this sensor, and measurement results of iron loss by using are shown.

Preparation, characterization and optoelectronic properties of nanodiamonds doped zinc oxide nanomaterials by a ball milling technique

Science.gov (United States)

Ullah, Hameed; Sohail, Muhammad; Malik, Uzma; Ali, Naveed; Bangash, Masroor Ahmad; Nawaz, Mohsan

2016-07-01

Zinc oxide (ZnO) is one of the very important metal oxides (MOs) for applications in optoelectronic devices which work in the blue and UV regions. However, to meet the challenges of obtaining ZnO nanomaterials suitable for practical applications, various modifications in physico-chemical properties are highly desirable. One of the ways adopted for altering the properties is to synthesize composite(s) of ZnO with various reinforcements. Here we report on the tuning of optoelectronic properties of ZnO upon doping by nanodiamonds (NDs) using the ball milling technique. A varying weight percent (wt.%) of NDs were ball milled for 2 h with ZnO nanoparticles prepared by a simple precipitation method. The effects of different parameters, the calcination temperature of ZnO, wt.% of NDs and mechanical milling upon the optoelectronic properties of the resulting ZnO-NDs nanocomposites have been investigated. The ZnO-NDs nanocomposites were characterized by IR spectroscopy, powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The UV-vis spectroscopy revealed the alteration in the bandgap energy (Eg ) of ZnO as a function of the calcination temperature of ZnO, changing the concentration of NDs, and mechanical milling of the resulting nanocomposites. The photoluminescence (PL) spectroscopy showed a decrease in the deep level emission (DLE) peaks and an increase in near-band-edge transition peaks as a result of the increasing concentration of NDs. The decrease in DLE and increase in band to band transition peaks were due to the strong interaction between the NDs and the Zn+; consequently, the Zn+ concentration decreased on the interstitial sites.

Real-time label-free monitoring of the cellular response to osmotic stress using conventional and long-range surface plasmons

Czech Academy of Sciences Publication Activity Database

Vala, Milan; Roberek, R.; Bocková, Markéta; Wegener, J.; Homola, Jiří

2013-01-01

Roč. 40, č. 1 (2013), s. 417-421 ISSN 0956-5663 R&D Projects: GA ČR GBP205/12/G118 Institutional support: RVO:67985882 Keywords : surface plasmon resonance * NRK cells * osmotic stress Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 6.451, year: 2013

Optoelectronic study and annealing stability of room temperature pulsed laser ablated ZnSe polycrystalline thin films

Energy Technology Data Exchange (ETDEWEB)

Khan, Taj Muhammad, E-mail: tajakashne@gmail.com; Zakria, M.; Ahmad, Mushtaq; Shakoor, Rana I.

2014-03-15

In principal, we described stability of the room temperature ZnSe thin films with thermal annealing deposited onto glass by pulsed laser deposition technique using third harmonic 355 nm of Nd: YAG laser beam. Optoelectronic analysis and stability with thermal annealing was described in terms of structural and optical properties. These properties were investigated via X-ray diffraction, atomic force microscope, scanning electron microscope, Raman, Fourier transform infrared and photoluminescence spectroscopies. From the strong reflection corresponding to the (1 1 1) plane (2θ=27.48°) and the longitudinal optical “LO” phonon modes at 250 cm{sup −1} and 500 cm{sup −1} in the X-ray diffraction and Raman spectra, a polycrystalline zincblende structure of the film was established. At 300 and 350 °C annealing temperatures, the film crystallites were preferentially oriented with the (1 1 1) plane parallel to the substrate and became amorphous at 400 °C. Atomic force microscopic images showed that the morphologies of ZnSe films became smooth with root mean squared roughness 9.86 nm after annealing at 300 and 350 °C while a rougher surface was observed for the amorphous film at 400 °C. Fourier transform infrared study illustrated the chemical nature and Zn–Se bonding in the deposited films. For the as-deposited and annealed samples at 300 and 350 °C, scanning electron micrographs revealed mono-dispersed indistinguishable ZnSe grains and smooth morphological structure which changed to a cracking and bumpy surface after annealing at 400 °C. The physical phenomenon of annealing induced morphological changes could be explained in terms of “structure zone model”. Excitonic emission at 456 nm was observed for both as-deposited and annealed film at 350 °C. The transmission spectrum shows oscillatory behavior because of the thin film interference and exhibited a high degree of transparency down to a wavelength ∼500 nm in the IR region. Energy band-gap was

The influence of target erosion grade in the optoelectronic properties of AZO coatings growth by magnetron sputtering

International Nuclear Information System (INIS)

Zubizarreta, C.; G-Berasategui, E.; Ciarsolo, I.; Barriga, J.; Gaspar, D.; Martins, R.; Fortunato, E.

2016-01-01

Graphical abstract: - Highlights: • High quality AZO films deposited at low temperature by RF magnetron sputtering. • Transmittance values of 84% and resistivity of 1.9 × 10"−"3 Ω cm were obtained. • Stable optoelectronic and structural properties during whole life of the target. • RF MS: robust and reliable for the industrial manufacture of AZO frontal electrode. - Abstract: Aluminum-doped zinc oxide (AZO) transparent conductor coating has emerged as promising substitute to tin-doped indium oxide (ITO) as electrode in optoelectronic applications such as photovoltaics or light emitting diodes (LEDs). Besides its high transmission in the visible spectral region and low resistivity, AZO presents a main advantage over other candidates such as graphene, carbon nanotubes or silver nanowires; it can be deposited using the technology industrially implemented to manufacture ITO layers, the magnetron sputtering (MS). This is a productive, reliable and green manufacturing technique. But to guarantee the robustness, reproducibility and reliability of the process there are still some issues to be addressed, such as the effect and control of the target state. In this paper a thorough study of the influence of the target erosion grade in developed coatings has been performed. AZO films have been deposited from a ceramic target by RF MS. Structure, optical transmittance and electrical properties of the produced coatings have been analyzed as function of the target erosion grade. No noticeable differences have been found neither in optoelectronic properties nor in the structure of the coatings, indicating that the RF MS is a stable and consistent process through the whole life of the target.

A Novel Optoelectronic Device Based on Correlated Two-Dimensional Fermions

Science.gov (United States)

Dianat, Pouya

Conventional metallic contacts can be replicated by quantum two dimensional charge (of Fermion) systems (2DFS). Unlike metals, the particle concentration of these "unconventional" systems can be accurately controlled in an extensive range and by means of external electronic or optical stimuli. A 2DFS can, hence, transition from a high-density kinetic liquid into a dilute-but highly correlated-gas state, in which inter-particle Coulombic interactions are significant. Such interactions contribute negatively, by so-called exchange-correlation energies, to the overall energetics of the system, and are manifested as a series negative quantum capacitance. This dissertation investigates the capacitive performance of a class of unconventional devices based on a planar metal-semiconductor-metal structure with an embedded 2DFS. They constitute an opto-electronically controlled variable capacitor, with record breaking figures-of-merit in capacitance tuning ranges of up to 7000 and voltage sensitivities as large as 400. Internal eld manipulations by localized depletion of a dense 2DFS account for the enlarged maximum and reduced minimum capacitances. The capacitance-voltage characteristics of these devices incur an anomalous "Batman" shape capacitance enhancement (CE) of up to 200% that may be triggered optically. The CE is attributed to the release and storage of exchange-correlation energies; from the "unconventional" plate and in the dielectric, respectively. This process is enforced by density manipulation of the 2DFS by a hybrid of an external eld and light-generated carriers. Under moderate optical powers, the capacitance becomes 43 times greater than the dark value; thus a new capacitance-based photodetection method is offered. This new capacitance based photodetection method has a range of applications in optoelectronics, particularly in the next generation of photonic integrated systems.

Optoelectronic analogue signal transfer for LHC detectors, 1991

CERN Document Server

Dowell, John D; Homer, R J; Jovanovic, P; Kenyon, I; Staley, R; Webster, K; Da Via, C; Feyt, J; Nappey, P; Stefanini, G; Dwir, B; Reinhart, F K; Davies, J; Green, N; Stewart, W; Young, T; Hall, G; Akesson, T; Jarlskog, G; Kröll, S; Nickerson, R; Jaroslawski, S; CERN. Geneva. Detector Research and Development Committee

1991-01-01

We propose to study and develop opto-electronic analogue front-ends based on electro-optic intensity modulators. These devices translate the detector electrical analogue signals into optical signals which are then transferred via optical fibres to photodetector receivers at the remote readout. In comparison with conventional solutions based on copper cables, this technique offers the advantages of high speed, very low power dissipation and transmission losses, compactness and immunity to electromagnetic interference. The linearity and dynamic range that can be obtained are more than adequate for central tracking detectors, and the proposed devices have considerable radiation- hardness capabilities. The large bandwidth and short transit times offer possibilities for improved triggering schemes. The proposed R&D programme is aimed at producing multi-channel "demonstrator" units for evaluation both in laboratory and beam tests. This will allow the choice of the most effective technology. A detailed study wil...

Si-Based Germanium Tin Semiconductor Lasers for Optoelectronic Applications

Science.gov (United States)

Al-Kabi, Sattar H. Sweilim

Silicon-based materials and optoelectronic devices are of great interest as they could be monolithically integrated in the current Si complementary metal-oxide-semiconductor (CMOS) processes. The integration of optoelectronic components on the CMOS platform has long been limited due to the unavailability of Si-based laser sources. A Si-based monolithic laser is highly desirable for full integration of Si photonics chip. In this work, Si-based germanium-tin (GeSn) lasers have been demonstrated as direct bandgap group-IV laser sources. This opens a completely new avenue from the traditional III-V integration approach. In this work, the material and optical properties of GeSn alloys were comprehensively studied. The GeSn films were grown on Ge-buffered Si substrates in a reduced pressure chemical vapor deposition system with low-cost SnCl4 and GeH4 precursors. A systematic study was done for thin GeSn films (thickness 400 nm) with Sn composition 5 to 17.5%. The room temperature photoluminescence (PL) spectra were measured that showed a gradual shift of emission peaks towards longer wavelength as Sn composition increases. Strong PL intensity and low defect density indicated high material quality. Moreover, the PL study of n-doped samples showed bandgap narrowing compared to the unintentionally p-doped (boron) thin films with similar Sn compositions. Finally, optically pumped GeSn lasers on Si with broad wavelength coverage from 2 to 3 mum were demonstrated using high-quality GeSn films with Sn compositions up to 17.5%. The achieved maximum Sn composition of 17.5% broke the acknowledged Sn incorporation limit using similar deposition chemistry. The highest lasing temperature was measured at 180 K with an active layer thickness as thin as 270 nm. The unprecedented lasing performance is due to the achievement of high material quality and a robust fabrication process. The results reported in this work show a major advancement towards Si-based electrically pumped mid

Design and test of optoelectronic system of alignment control based on CCD camera

Science.gov (United States)

Anisimov, A. G.; Gorbachyov, A. A.; Krasnyashchikh, A. V.; Pantushin, A. N.; Timofeev, A. N.

2008-10-01

In this work, design, implementation and test of a system intended for positioning of the elements of turbine units relative to the line of shaft with high precision, are discussed. A procedure of the conversion of coordinates from the instrument system into the system connected with the practical position of the axis of turbine has been devised. It is shown that optoelectronic systems of aligment built by autoreflexive scheme can be used for high precision measurements.

Design and Radiation Assessment of Optoelectronic Transceiver Circuits for ITER

CERN Document Server

Leroux, P; Van Uffelen, M; Steyaert, M

2008-01-01

The presented work describes the design and characterization results of different electronic building blocks for a MGy gamma radiation tolerant optoelectronic transceiver aiming at ITER applications. The circuits are implemented using the 70GHz fT SiGe HBT in a 0.35μm BiCMOS technology. A VCSEL driver circuit has been designed and measured up to a TID of 1.6 MGy and up to a bit rate of 622Mbps. No significant degradation is seen in the eye opening of the output signal. On the receiver side, both a 1GHz, 3kΩ transimpedance and a 5GHz Cherry-Hooper amplifier with over 20dB voltage gain have been designed.

Optoelectronic and Photovoltaic Properties of the Air-Stable Organohalide Semiconductor (CH 3 NH 3 ) 3 Bi 2 I 9

KAUST Repository

Abulikemu, Mutalifu; Ould-Chikh, Samy; Miao, Xiaohe; Alarousu, Erkki; Banavoth, Murali; Ngongang Ndjawa, Guy Olivier; Barbe, Jeremy; El Labban, Abdulrahman; Amassian, Aram; Del Gobbo, Silvano

2016-01-01

Lead halide perovskite materials have shown excellent optoelectronic as well as photovoltaic properties. However, the presence of lead and the chemical instability relegate lead halide perovskites to research applications only. Here, we investigate

Heteroclinic dynamics of coupled semiconductor lasers with optoelectronic feedback.

Science.gov (United States)

Shahin, S; Vallini, F; Monifi, F; Rabinovich, M; Fainman, Y

2016-11-15

Generalized Lotka-Volterra (GLV) equations are important equations used in various areas of science to describe competitive dynamics among a population of N interacting nodes in a network topology. In this Letter, we introduce a photonic network consisting of three optoelectronically cross-coupled semiconductor lasers to realize a GLV model. In such a network, the interaction of intensity and carrier inversion rates, as well as phases of laser oscillator nodes, result in various dynamics. We study the influence of asymmetric coupling strength and frequency detuning between semiconductor lasers and show that inhibitory asymmetric coupling is required to achieve consecutive amplitude oscillations of the laser nodes. These studies were motivated primarily by the dynamical models used to model brain cognitive activities and their correspondence with dynamics obtained among coupled laser oscillators.

Software for Use with Optoelectronic Measuring Tool

Science.gov (United States)

Ballard, Kim C.

2004-01-01

A computer program has been written to facilitate and accelerate the process of measurement by use of the apparatus described in "Optoelectronic Tool Adds Scale Marks to Photographic Images" (KSC-12201). The tool contains four laser diodes that generate parallel beams of light spaced apart at a known distance. The beams of light are used to project bright spots that serve as scale marks that become incorporated into photographic images (including film and electronic images). The sizes of objects depicted in the images can readily be measured by reference to the scale marks. The computer program is applicable to a scene that contains the laser spots and that has been imaged in a square pixel format that can be imported into a graphical user interface (GUI) generated by the program. It is assumed that the laser spots and the distance(s) to be measured all lie in the same plane and that the plane is perpendicular to the line of sight of the camera used to record the image

Nanopatterned Metallic Films for Use As Transparent Conductive Electrodes in Optoelectronic Devices

KAUST Repository

Catrysse, Peter B.

2010-08-11

We investigate the use of nanopatterned metallic films as transparent conductive electrodes in optoelectronic devices. We find that the physics of nanopatterned electrodes, which are often optically thin metallic films, differs from that of optically thick metallic films. We analyze the optical properties when performing a geometrical transformation that maintains the electrical properties. For one-dimensional patterns of metallic wires, the analysis favors tall and narrow wires. Our design principles remain valid for oblique incidence and readily carry over to two-dimensional patterns. © 2010 American Chemical Society.

Capacity-oriented curriculum system of optoelectronics in the context of large category cultivation

Science.gov (United States)

Luo, Yuan; Hu, Zhangfang; Zhang, Yi

2017-08-01

In order to cultivate the innovative talents with the comprehensive development to meet the talents demand for development of economic society, Chongqing University of Posts and Telecommunications implements cultivation based on broadening basic education and enrolment in large category of general education. Optoelectronic information science and engineering major belongs to the electronic engineering category. The "2 +2" mode is utilized for personnel training, where students are without major in the first and second year and assigned to a major within the major categories in the end of the second year. In the context of the comprehensive cultivation, for the changes in the demand for professionals in the global competitive environment with the currently rapid development, especially the demand for the professional engineering technology personnel suitable to industry and development of local economic society, the concept of CDIO engineering ability cultivation is used for reference. Thus the curriculum system for the three-node structure optoelectronic information science and engineering major is proposed, which attaches great importance to engineering practice and innovation cultivation under the background of the comprehensive cultivation. The conformity between the curriculum system and the personnel training objectives is guaranteed effectively, and the consistency between the teaching philosophy and the teaching behavior is enhanced. Therefore, the idea of major construction is clear with specific characteristics.

Optoelectronic properties of transparent p-type semiconductor Cu{sub x}S thin films

Energy Technology Data Exchange (ETDEWEB)

Parreira, P.; Valente, J. [ICEMS, IST-UTL, Lisboa (Portugal); Lavareda, G. [Departamento de Fisica, IST-UTL, Lisboa (Portugal); Nunes, F.T. [Departamento de Ciencia dos Materiais, FCT-UNL, Caparica (Portugal); Amaral, A. [Departamento de Fisica, IST-UTL, Lisboa (Portugal); ICEMS, IST-UTL, Lisboa (Portugal); Carvalho, C.N. de [Departamento de Ciencia dos Materiais, FCT-UNL, Caparica (Portugal); ICEMS, IST-UTL, Lisboa (Portugal)

2010-07-15

Nowadays, among the available transparent semiconductors for device use, the great majority (if not all) have n-type conductivity. The fabrication of a transparent p-type semiconductor with good optoelectronic properties (comparable to those of n-type: InO{sub x}, ITO, ZnO{sub x} or FTO) would significantly broaden the application field of thin films. However, until now no material has yet presented all the required properties. Cu{sub 2}S is a p-type narrow-band-gap material with an average optical transmittance of about 60% in the visible range for 50 nm thick films. However, due to its high conductivity at room temperature, 10 nm in thickness seems to be appropriate for device use. Cu{sub 2}S thin films with 10 nm in thickness have an optical visible transmittance of about 85% rendering them as very good candidates for transparent p-type semiconductors. In this work Cu{sub x}S thin films were deposited on alkali-free (AF) glass by thermal evaporation. The objective was not only the determination of its optoelectronic properties but also the feasibility of an active layer in a p-type thin film transistor. In our Cu{sub x}S thin films, p-type high conductivity with a total visible transmittance of about 50% have been achieved. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Evaluation of the structural, optical and electrical properties of AZO thin films prepared by chemical bath deposition for optoelectronics

Science.gov (United States)

Kumar, K. Deva Arun; Valanarasu, S.; Rosario, S. Rex; Ganesh, V.; Shkir, Mohd.; Sreelatha, C. J.; AlFaify, S.

2018-04-01

Aluminum doped zinc oxide (AZO) thin films for electrode applications were deposited on glass substrates using chemical bath deposition (CBD) method. The influence of deposition time on the structural, morphological, and opto-electrical properties of AZO films were investigated. Structural studies confirmed that all the deposited films were hexagonal wurtzite structure with polycrystalline nature and exhibited (002) preferential orientation. There is no other impurity phases were detected for different deposition time. Surface morphological images shows the spherically shaped grains are uniformly arranged on to the entire film surface. The EDS spectrum confirms the presence of Zn, O and Al elements in deposited AZO film. The observed optical transmittance is high (87%) in the visible region, and the calculated band gap value is 3.27 eV. In this study, the transmittance value is decreased with increasing deposition time. The room temperature PL spectrum exposed that AZO thin film deposited at (60 min) has good optical quality with less defect density. The minimum electrical resistivity and maximum carrier concentration values were observed as 8.53 × 10-3(Ω cm) and 3.53 × 1018 cm-3 for 60 min deposited film, respectively. The obtained figure of merit (ϕ) value 3.05 × 10-3(Ω/sq)- 1 is suggested for an optoelectronic device.

Surface plasmon resonance biosensor for direct detection of antibody against Epstein-Barr virus

Czech Academy of Sciences Publication Activity Database

Vaisocherová, Hana; Mrkvová, Kateřina; Piliarik, Marek; Jinoch, P.; Šteinbachová, M.; Homola, Jiří

2007-01-01

Roč. 22, č. 6 (2007), s. 1020-1026 ISSN 0956-5663 R&D Projects: GA ČR GA102/03/0633; GA ČR(CZ) GA303/03/0249 Grant - others:European Commission(XE) QLK4-CT-2002-02323 Institutional research plan: CEZ:AV0Z20670512 Keywords : biosensors * surface plasmon resonance * optical sensors Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 5.061, year: 2007

Recent developments of truly stretchable thin film electronic and optoelectronic devices.

Science.gov (United States)

Zhao, Juan; Chi, Zhihe; Yang, Zhan; Chen, Xiaojie; Arnold, Michael S; Zhang, Yi; Xu, Jiarui; Chi, Zhenguo; Aldred, Matthew P

2018-03-29

Truly stretchable electronics, wherein all components themselves permit elastic deformation as the whole devices are stretched, exhibit unique advantages over other strategies, such as simple fabrication process, high integrity of entire components and intimate integration with curvilinear surfaces. In contrast to the stretchable devices using stretchable interconnectors to integrate with rigid active devices, truly stretchable devices are realized with or without intentionally employing structural engineering (e.g. buckling), and the whole device can be bent, twisted, or stretched to meet the demands for practical applications, which are beyond the capability of conventional flexible devices that can only bend or twist. Recently, great achievements have been made toward truly stretchable electronics. Here, the contribution of this review is an effort to provide a panoramic view of the latest progress concerning truly stretchable electronic devices, of which we give special emphasis to three kinds of thin film electronic and optoelectronic devices: (1) thin film transistors, (2) electroluminescent devices (including organic light-emitting diodes, light-emitting electrochemical cells and perovskite light-emitting diodes), and (3) photovoltaics (including organic photovoltaics and perovskite solar cells). We systematically discuss the device design and fabrication strategies, the origin of device stretchability and the relationship between the electrical and mechanical behaviors of the devices. We hope that this review provides a clear outlook of these attractive stretchable devices for a broad range of scientists and attracts more researchers to devote their time to this interesting research field in both industry and academia, thus encouraging more intelligent lifestyles for human beings in the coming future.

Optoelectronic properties of CC2TA towards a good TADF material

Science.gov (United States)

Mishra, Ashok Kumar

2018-05-01

2,4-bis{f3-(9H-carbazol-9-yl)-9H-carbazol-9-yl}-6-phenyl-1,3,5-triazine (CC2TA) is a triazine derivatives in which the acceptor phenyltriazine unit is used as the central skeleton and donor bicarbazole units are bonded to both ends of the skeleton. Molecular orbital calculations exhibit that the HOMO and LUMO are locally allocated chiefly in the bicarbazole and phenyltriazine units, respectively. There are a class of organic molecules and polymers which exhibit semiconductor behavior because of nearly free conjugate π-electrons. Hopping of these electrons in molecules forms different excited singlet and triplet states named as excitons. Some of these organic molecules can be set to emit photons by triplet-singlet excitonic transition via a process called Thermally Activated Delayed Fluorescence (TADF) which is exploited for designing the Organic Light Emitting diode (OLED.) CC2TA is one of these reported noble metal-free TADF molecules which offers unique opto electronic properties arising from the reverse intersystem crossing between the lowest singlet (S) and triplet (T) excited states. Its ability to harvest triplet excitons for fluorescence through facilitated reverse intersystem crossing (T→S) could directly impact their properties and performances, which is attractive for a wide variety of low-cost optoelectronic device. In the present study, the CC2TA compounds have been taken up for the investigation of various optoelectronic properties including the thermally activated delayed fluorescence (TADF) by using the Koopmans Method and Density Functional Theory. The present study discusses the utility of the CC2TA organic semiconductor as a suitable TADF material essential for developing an efficient Organic Light Emitting Diode (OLED).

The impact of semiconductor, electronics and optoelectronic industries on downstream perfluorinated chemical contamination in Taiwanese rivers

International Nuclear Information System (INIS)

Lin, Angela Yu-Chen; Panchangam, Sri Chandana; Lo, Chao-Chun

2009-01-01

This study provides the first evidence on the influence of the semiconductor and electronics industries on perfluorinated chemicals (PFCs) contamination in receiving rivers. We have quantified ten PFCs, including perfluoroalkyl sulfonates (PFASs: PFBS, PFHxS, PFOS) and perfluoroalkyl carboxylates (PFCAs: PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA) in semiconductor, electronic, and optoelectronic industrial wastewaters and their receiving water bodies (Taiwan's Keya, Touchien, and Xiaoli rivers). PFOS was found to be the major constituent in semiconductor wastewaters (up to 0.13 mg/L). However, different PFC distributions were found in electronics plant wastewaters; PFOA was the most significant PFC, contributing on average 72% to the effluent water samples, followed by PFOS (16%) and PFDA (9%). The distribution of PFCs in the receiving rivers was greatly impacted by industrial sources. PFOS, PFOA and PFDA were predominant and prevalent in all the river samples, with PFOS detected at the highest concentrations (up to 5.4 μg/L). - The semiconductor, electronics and optoelectronic industries are the primary source of PFC contamination in downstream aqueous environments

Density functional study of a typical thiol tethered on a gold surface: ruptures under normal or parallel stretch

International Nuclear Information System (INIS)

Wang, Guan M; Sandberg, William C; Kenny, Steven D

2006-01-01

The mechanical and dynamical properties of a model Au(111)/thiol surface system were investigated by using localized atomic-type orbital density functional theory in the local density approximation. Relaxing the system gives a configuration where the sulfur atom forms covalent bonds to two adjacent gold atoms as the lowest energy structure. Investigations based on ab initio molecular dynamics simulations at 300, 350 and 370 K show that this tethering system is stable. The rupture behaviour between the thiol and the surface was studied by displacing the free end of the thiol. Calculated energy profiles show a process of multiple successive ruptures that account for experimental observations. The process features successive ruptures of the two Au-S bonds followed by the extraction of one S-bonded Au atom from the surface. The force required to rupture the thiol from the surface was found to be dependent on the direction in which the thiol was displaced, with values comparable with AFM measurements. These results aid the understanding of failure dynamics of Au(111)-thiol-tethered biosurfaces in microfluidic devices where fluidic shear and normal forces are of concern

Development of the apparatus for measuring magnetic properties of electrical steel sheets in arbitrary directions under compressive stress normal to their surface

Directory of Open Access Journals (Sweden)

Yoshitaka Maeda

2017-05-01

Full Text Available In designing motors, one must grasp the magnetic properties of electrical steel sheets considering actual conditions in motors. Especially important is grasping the stress dependence of magnetic power loss. This paper describes a newly developed apparatus to measure two-dimensional (2-D magnetic properties (properties under the arbitrary alternating and the rotating flux conditions of electrical steel sheets under compressive stress normal to the sheet surface. The apparatus has a 2-D magnetic excitation circuit to generate magnetic fields in arbitrary directions in the evaluation area. It also has a pressing unit to apply compressive stress normal to the sheet surface. During measurement, it is important to apply uniform stress throughout the evaluation area. Therefore, we have developed a new flux density sensor using needle probe method. It is composed of thin copper foils sputtered on electrical steel sheets. By using this sensor, the stress can be applied to the surface of the specimen without influence of this sensor. This paper described the details of newly developed apparatus with this sensor, and measurement results of iron loss by using are shown.

Probing individal subcells of fully printed and coated polymer tandem solar cells using multichromatic opto-electronic characterization methods

DEFF Research Database (Denmark)

Larsen-Olsen, Thue Trofod; Andersen, Thomas Rieks; Dam, Henrik Friis

2015-01-01

In this study, a method to opto-electronically probe the individual junctions and carrier transport across interfaces in fully printed and coated tandem polymer solar cells is described, enabling the identification of efficiency limiting printing/coating defects. The methods used are light beam...

Synthesis, characterization, and evaluation of a superficially porous particle with unique, elongated pore channels normal to the surface.

Science.gov (United States)

Wei, Ta-Chen; Mack, Anne; Chen, Wu; Liu, Jia; Dittmann, Monika; Wang, Xiaoli; Barber, William E

2016-04-01

In recent years, superficially porous particles (SPPs) have drawn great interest because of their special particle characteristics and improvement in separation efficiency. Superficially porous particles are currently manufactured by adding silica nanoparticles onto solid cores using either a multistep multilayer process or one-step coacervation process. The pore size is mainly controlled by the size of the silica nanoparticles and the tortuous pore channel geometry is determined by how those nanoparticles randomly aggregate. Such tortuous pore structure is also similar to that of all totally porous particles used in HPLC today. In this article, we report on the development of a next generation superficially porous particle with a unique pore structure that includes a thinner shell thickness and ordered pore channels oriented normal to the particle surface. The method of making the new superficially porous particles is a process called pseudomorphic transformation (PMT), which is a form of micelle templating. Porosity is no longer controlled by randomly aggregated nanoparticles but rather by micelles that have an ordered liquid crystal structure. The new particle possesses many advantages such as a narrower particle size distribution, thinner porous layer with high surface area and, most importantly, highly ordered, non-tortuous pore channels oriented normal to the particle surface. This PMT process has been applied to make 1.8-5.1μm SPPs with pore size controlled around 75Å and surface area around 100m(2)/g. All particles with different sizes show the same unique pore structure with tunable pore size and shell thickness. The impact of the novel pore structure on the performance of these particles is characterized by measuring van Deemter curves and constructing kinetic plots. Reduced plate heights as low as 1.0 have been achieved on conventional LC instruments. This indicates higher efficiency of such particles compared to conventional totally porous and

Carbon dots—Emerging light emitters for bioimaging, cancer therapy and optoelectronics

KAUST Repository

Hola, Katerina; Zhang, Yu; Wang, Yu; Giannelis, Emmanuel P.; Zboril, Radek; Rogach, Andrey L.

2014-01-01

© 2014 Elsevier Ltd. All rights reserved. Carbon dots represent an emerging class of fluorescent materials and provide a broad application potential in various fields of biomedicine and optoelectronics. In this review, we introduce various synthetic strategies and basic photoluminescence properties of carbon dots, and then address their advanced in vitro and in vivo bioapplications including cell imaging, photoacoustic imaging, photodynamic therapy and targeted drug delivery. We further consider the applicability of carbon dots as components of light emitting diodes, which include carbon dot based electroluminescence, optical down-conversion, and hybrid plasmonic devices. The review concludes with an outlook towards future developments of these emerging light-emitting materials.

Photon management of GaN-based optoelectronic devices via nanoscaled phenomena

KAUST Repository

Tsai, Yu-Lin

2016-09-06

Photon management is essential in improving the performances of optoelectronic devices including light emitting diodes, solar cells and photo detectors. Beyond the advances in material growth and device structure design, photon management via nanoscaled phenomena have also been demonstrated as a promising way for further modifying/improving the device performance. The accomplishments achieved by photon management via nanoscaled phenomena include strain-induced polarization field management, crystal quality improvement, light extraction/harvesting enhancement, radiation pattern control, and spectrum management. In this review, we summarize recent development, challenges and underlying physics of photon management in GaN-based light emitting diodes and solar cells. (C) 2016 Elsevier Ltd. All rights reserved.

Field Effect Optoelectronic Modulation of Quantum-Confined Carriers in Black Phosphorus.

Science.gov (United States)

Whitney, William S; Sherrott, Michelle C; Jariwala, Deep; Lin, Wei-Hsiang; Bechtel, Hans A; Rossman, George R; Atwater, Harry A

2017-01-11

We report measurements of the infrared optical response of thin black phosphorus under field-effect modulation. We interpret the observed spectral changes as a combination of an ambipolar Burstein-Moss (BM) shift of the absorption edge due to band-filling under gate control, and a quantum confined Franz-Keldysh (QCFK) effect, phenomena that have been proposed theoretically to occur for black phosphorus under an applied electric field. Distinct optical responses are observed depending on the flake thickness and starting carrier concentration. Transmission extinction modulation amplitudes of more than two percent are observed, suggesting the potential for use of black phosphorus as an active material in mid-infrared optoelectronic modulator applications.

Exciton confinement in organic dendrimer quantum wells for opto-electronic applications

Science.gov (United States)

Lupton, J. M.; Samuel, I. D. W.; Burn, P. L.; Mukamel, S.

2002-01-01

Organic dendrimers are a fascinating new class of materials for opto-electronic applications. We present coupled electronic oscillator calculations on novel nanoscale conjugated dendrimers for use in organic light-emitting diodes. Strong confinement of excitations at the center of the dendrimers is observed, which accounts for the dependence of intermolecular interactions and charge transport on the degree of branching of the dendrimer. The calculated absorption spectra are in excellent agreement with the measured data and show that benzene rings are shared between excitations on the linear segments of the hyperbranched molecules. The coupled electronic oscillator approach is ideally suited to treat large dendritic molecules.

Carbon dots—Emerging light emitters for bioimaging, cancer therapy and optoelectronics

KAUST Repository

Hola, Katerina

2014-10-01

© 2014 Elsevier Ltd. All rights reserved. Carbon dots represent an emerging class of fluorescent materials and provide a broad application potential in various fields of biomedicine and optoelectronics. In this review, we introduce various synthetic strategies and basic photoluminescence properties of carbon dots, and then address their advanced in vitro and in vivo bioapplications including cell imaging, photoacoustic imaging, photodynamic therapy and targeted drug delivery. We further consider the applicability of carbon dots as components of light emitting diodes, which include carbon dot based electroluminescence, optical down-conversion, and hybrid plasmonic devices. The review concludes with an outlook towards future developments of these emerging light-emitting materials.

The influence of target erosion grade in the optoelectronic properties of AZO coatings growth by magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Zubizarreta, C., E-mail: cristina.zubizarreta@tekniker.es [IK4-Tekniker, Research Centre, c/ Iñaki Goenaga, 5, 20600 Eibar, Guipuzkoa (Spain); G-Berasategui, E.; Ciarsolo, I.; Barriga, J. [IK4-Tekniker, Research Centre, c/ Iñaki Goenaga, 5, 20600 Eibar, Guipuzkoa (Spain); Gaspar, D.; Martins, R.; Fortunato, E. [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa (Portugal)

2016-09-01

Graphical abstract: - Highlights: • High quality AZO films deposited at low temperature by RF magnetron sputtering. • Transmittance values of 84% and resistivity of 1.9 × 10{sup −3} Ω cm were obtained. • Stable optoelectronic and structural properties during whole life of the target. • RF MS: robust and reliable for the industrial manufacture of AZO frontal electrode. - Abstract: Aluminum-doped zinc oxide (AZO) transparent conductor coating has emerged as promising substitute to tin-doped indium oxide (ITO) as electrode in optoelectronic applications such as photovoltaics or light emitting diodes (LEDs). Besides its high transmission in the visible spectral region and low resistivity, AZO presents a main advantage over other candidates such as graphene, carbon nanotubes or silver nanowires; it can be deposited using the technology industrially implemented to manufacture ITO layers, the magnetron sputtering (MS). This is a productive, reliable and green manufacturing technique. But to guarantee the robustness, reproducibility and reliability of the process there are still some issues to be addressed, such as the effect and control of the target state. In this paper a thorough study of the influence of the target erosion grade in developed coatings has been performed. AZO films have been deposited from a ceramic target by RF MS. Structure, optical transmittance and electrical properties of the produced coatings have been analyzed as function of the target erosion grade. No noticeable differences have been found neither in optoelectronic properties nor in the structure of the coatings, indicating that the RF MS is a stable and consistent process through the whole life of the target.

Computational and theoretical modeling of pH and flow effects on the early-stage non-equilibrium self-assembly of optoelectronic peptides

Science.gov (United States)

Mansbach, Rachael; Ferguson, Andrew

Self-assembling π-conjugated peptides are attractive candidates for the fabrication of bioelectronic materials possessing optoelectronic properties due to electron delocalization over the conjugated peptide groups. We present a computational and theoretical study of an experimentally-realized optoelectronic peptide that displays triggerable assembly in low pH to resolve the microscopic effects of flow and pH on the non-equilibrium morphology and kinetics of assembly. Using a combination of molecular dynamics simulations and hydrodynamic modeling, we quantify the time and length scales at which convective flows employed in directed assembly compete with microscopic diffusion to influence assembly. We also show that there is a critical pH below which aggregation proceeds irreversibly, and quantify the relationship between pH, charge density, and aggregate size. Our work provides new fundamental understanding of pH and flow of non-equilibrium π-conjugated peptide assembly, and lays the groundwork for the rational manipulation of environmental conditions and peptide chemistry to control assembly and the attendant emergent optoelectronic properties. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award # DE-SC0011847, and by the Computational Science and Engineering Fellowship from the University of Illinois at Urbana-Champaign.

A Multi-Wavelength Opto-Electronic Patch Sensor to Effectively Detect Physiological Changes against Human Skin Types.

Science.gov (United States)

Yan, Liangwen; Hu, Sijung; Alzahrani, Abdullah; Alharbi, Samah; Blanos, Panagiotis

2017-06-21

Different skin pigments among various ethnic group people have an impact on spectrometric illumination on skin surface. To effectively capture photoplethysmographic (PPG) signals, a multi-wavelength opto-electronic patch sensor (OEPS) together with a schematic architecture of electronics were developed to overcome the drawback of present PPG sensor. To perform a better in vivo physiological measurement against skin pigments, optimal illuminations in OEPS, whose wavelength is compatible with a specific skin type, were optimized to capture a reliable physiological sign of heart rate (HR). A protocol was designed to investigate an impact of five skin types in compliance with Von Luschan's chromatic scale. Thirty-three healthy male subjects between the ages of 18 and 41 were involved in the protocol implemented by means of the OEPS system. The results show that there is no significant difference ( p: 0.09, F = 3.0) in five group tests with the skin types across various activities throughout a series of consistent measurements. The outcome of the present study demonstrates that the OEPS, with its multi-wavelength illumination characteristics, could open a path in multiple applications of different ethnic groups with cost-effective health monitoring.

A Multi-Wavelength Opto-Electronic Patch Sensor to Effectively Detect Physiological Changes against Human Skin Types

Directory of Open Access Journals (Sweden)

Liangwen Yan

2017-06-01

Full Text Available Different skin pigments among various ethnic group people have an impact on spectrometric illumination on skin surface. To effectively capture photoplethysmographic (PPG signals, a multi-wavelength opto-electronic patch sensor (OEPS together with a schematic architecture of electronics were developed to overcome the drawback of present PPG sensor. To perform a better in vivo physiological measurement against skin pigments, optimal illuminations in OEPS, whose wavelength is compatible with a specific skin type, were optimized to capture a reliable physiological sign of heart rate (HR. A protocol was designed to investigate an impact of five skin types in compliance with Von Luschan’s chromatic scale. Thirty-three healthy male subjects between the ages of 18 and 41 were involved in the protocol implemented by means of the OEPS system. The results show that there is no significant difference (p: 0.09, F = 3.0 in five group tests with the skin types across various activities throughout a series of consistent measurements. The outcome of the present study demonstrates that the OEPS, with its multi-wavelength illumination characteristics, could open a path in multiple applications of different ethnic groups with cost-effective health monitoring.

Agreement between fiber optic and optoelectronic systems for quantifying sagittal plane spinal curvature in sitting.

Science.gov (United States)

Cloud, Beth A; Zhao, Kristin D; Breighner, Ryan; Giambini, Hugo; An, Kai-Nan

2014-07-01

Spinal posture affects how individuals function from a manual wheelchair. There is a need to directly quantify spinal posture in this population to ultimately improve function. A fiber optic system, comprised of an attached series of sensors, is promising for measuring large regions of the spine in individuals sitting in a wheelchair. The purpose of this study was to determine the agreement between fiber optic and optoelectronic systems for measuring spinal curvature, and describe the range of sagittal plane spinal curvatures in natural sitting. Able-bodied adults (n = 26, 13 male) participated. Each participant assumed three sitting postures: natural, slouched (accentuated kyphosis), and extension (accentuated lordosis) sitting. Fiber optic (ShapeTape) and optoelectronic (Optotrak) systems were applied to the skin over spinous processes from S1 to C7 and used to measure sagittal plane spinal curvature. Regions of kyphosis and lordosis were identified. A Cobb angle-like method was used to quantify lordosis and kyphosis. Generalized linear model and Bland-Altman analyses were used to assess agreement. A strong correlation exists between curvature values obtained with Optotrak and ShapeTape (R(2) = 0.98). The mean difference between Optotrak and ShapeTape for kyphosis in natural, extension, and slouched postures was 4.30° (95% LOA: -3.43 to 12.04°), 3.64° (95% LOA: -1.07 to 8.36°), and 4.02° (95% LOA: -2.80 to 10.84°), respectively. The mean difference for lordosis, when present, in natural and extension postures was 2.86° (95% LOA: -1.18 to 6.90°) and 2.55° (95% LOA: -3.38 to 8.48°), respectively. In natural sitting, the mean ± SD of kyphosis values was 35.07 ± 6.75°. Lordosis was detected in 8/26 participants: 11.72 ± 7.32°. The fiber optic and optoelectronic systems demonstrate acceptable agreement for measuring sagittal plane thoracolumbar spinal curvature. Copyright © 2014 Elsevier B.V. All rights reserved.

Using surfaces, ligands, and dimensionality to obtain desired nanostructure properties

Science.gov (United States)

Nagpal, Prashant; Singh, Vivek; Ding, Yuchen

2014-03-01

Nanostructured materials are intensively investigated to obtain material properties different from their bulk counterparts. It has been demonstrated that nanoscaled semiconductor can have interesting size, shape and morphology dependent optoelectronic properties. But the effect of surfaces, ligands and dimensionality (0D quantum dots to 2D nanosheets) has been largely unexplored. Here, we will show how tuning the surface and dimensionality can affect the electronic states of the semiconductor, and how these states can play an important role in their fundamental photophysical properties or thermal transport. Using the specific case for silicon, we will show how ``new'' surface states in small uniform can lead to light absorption/emission without phonon assistance, while hindering the phonon-drag of charge carriers leading to low Seebeck coefficient for thermoelectric applications. These measurements will shed light on designing appropriate surface, size, and dimensionality for desired applications of nanostructured films.

Optoelectronic properties of Black-Silicon generated through inductively coupled plasma (ICP) processing for crystalline silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Hirsch, Jens, E-mail: J.Hirsch@emw.hs-anhalt.de [Anhalt University of Applied Sciences, Faculty EMW, Bernburger Str. 55, DE-06366 Köthen (Germany); Fraunhofer Center for Silicon Photovoltaics CSP, Otto-Eißfeldt-Str. 12, DE-06120 Halle (Saale) (Germany); Gaudig, Maria; Bernhard, Norbert [Anhalt University of Applied Sciences, Faculty EMW, Bernburger Str. 55, DE-06366 Köthen (Germany); Lausch, Dominik [Fraunhofer Center for Silicon Photovoltaics CSP, Otto-Eißfeldt-Str. 12, DE-06120 Halle (Saale) (Germany)

2016-06-30

Highlights: • Fabrication of black silicon through inductively coupled plasma (ICP) processing. • Suppressed formation a self-bias and therefore a reduced ion bombardment of the silicon sample. • Reduction of the average hemispherical reflection between 300 and 1120 nm up to 8% within 5 min ICP process time. • Reflection is almost independent of the angle of incidence up to 60°. • 2.5 ms effective lifetime at 10{sup 15} cm{sup −3} MCD after ALD Al{sub 2}O{sub 3} surface passivation. - Abstract: The optoelectronic properties of maskless inductively coupled plasma (ICP) generated black silicon through SF{sub 6} and O{sub 2} are analyzed by using reflection measurements, scanning electron microscopy (SEM) and quasi steady state photoconductivity (QSSPC). The results are discussed and compared to capacitively coupled plasma (CCP) and industrial standard wet chemical textures. The ICP process forms parabolic like surface structures in a scale of 500 nm. This surface structure reduces the average hemispherical reflection between 300 and 1120 nm up to 8%. Additionally, the ICP texture shows a weak increase of the hemispherical reflection under tilted angles of incidence up to 60°. Furthermore, we report that the ICP process is independent of the crystal orientation and the surface roughness. This allows the texturing of monocrystalline, multicrystalline and kerf-less wafers using the same parameter set. The ICP generation of black silicon does not apply a self-bias on the silicon sample. Therefore, the silicon sample is exposed to a reduced ion bombardment, which reduces the plasma induced surface damage. This leads to an enhancement of the effective charge carrier lifetime up to 2.5 ms at 10{sup 15} cm{sup −3} minority carrier density (MCD) after an atomic layer deposition (ALD) with Al{sub 2}O{sub 3}. Since excellent etch results were obtained already after 4 min process time, we conclude that the ICP generation of black silicon is a promising technique

A dual surface plasmon resonance assay for the determination of ribonuclease H activity

Czech Academy of Sciences Publication Activity Database

Šípová, Hana; Vaisocherová, Hana; Štepánek, J.; Homola, Jiří

2010-01-01

Roč. 26, č. 4 (2010), s. 1605-1611 ISSN 0956-5663 R&D Projects: GA AV ČR KAN200670701; GA MŠk OC09058; GA ČR GA202/09/0193 Grant - others:Univerzita Karlova(CZ) SVV-2010-261 304 Institutional research plan: CEZ:AV0Z20670512 Keywords : Surface plasmon resonance * Enzyme activity assay * Ribonuclease H * Biosensor Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 5.361, year: 2010

Pseudo--Normals for Signed Distance Computation

DEFF Research Database (Denmark)

Aanæs, Henrik; Bærentzen, Jakob Andreas

2003-01-01

the relation of a point to a mesh. At the vertices and edges of a triangle mesh, the surface is not \\$C\\^1\\$ continuous. Hence, the normal is undefined at these loci. Thürmer and Wüthrich proposed the \\$\\backslash\\$emph{angle weighted pseudo--normal} as a way to deal with this problem. In this paper, we...

Recent Developments of an Opto-Electronic THz Spectrometer for High-Resolution Spectroscopy.

Science.gov (United States)

Hindle, Francis; Yang, Chun; Mouret, Gael; Cuisset, Arnaud; Bocquet, Robin; Lampin, Jean-François; Blary, Karine; Peytavit, Emilien; Akalin, Tahsin; Ducournau, Guillaume

2009-01-01

A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined and the insensitivity of this technique to aerosols is demonstrated by the analysis of cigarette smoke. A multiple pass sample cell has been used to obtain a sensitivity improvement allowing transitions of the volatile organic compounds to be observed. A solution to the frequency metrology is presented and promises to yield accurate molecular line center measurements.

Recent Developments of an Opto-Electronic THz Spectrometer for High-Resolution Spectroscopy

Science.gov (United States)

Hindle, Francis; Yang, Chun; Mouret, Gael; Cuisset, Arnaud; Bocquet, Robin; Lampin, Jean-François; Blary, Karine; Peytavit, Emilien; Akalin, Tahsin; Ducournau, Guillaume

2009-01-01

A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined and the insensitivity of this technique to aerosols is demonstrated by the analysis of cigarette smoke. A multiple pass sample cell has been used to obtain a sensitivity improvement allowing transitions of the volatile organic compounds to be observed. A solution to the frequency metrology is presented and promises to yield accurate molecular line center measurements. PMID:22291552

Formulae for the determination of the elements of the E\\"otvos matrix of the Earth's normal gravity field and a relation between normal and actual Gaussian curvature

OpenAIRE

Manoussakis, G.; Delikaraoglou, D.

2011-01-01

In this paper we form relations for the determination of the elements of the E\\"otv\\"os matrix of the Earth's normal gravity field. In addition a relation between the Gauss curvature of the normal equipotential surface and the Gauss curvature of the actual equipotential surface both passing through the point P is presented. For this purpose we use a global Cartesian system (X, Y, Z) and use the variables X, and Y to form a local parameterization a normal equipotential surface to describe its ...

Deformation associated with continental normal faults

Science.gov (United States)

Resor, Phillip G.

Deformation associated with normal fault earthquakes and geologic structures provide insights into the seismic cycle as it unfolds over time scales from seconds to millions of years. Improved understanding of normal faulting will lead to more accurate seismic hazard assessments and prediction of associated structures. High-precision aftershock locations for the 1995 Kozani-Grevena earthquake (Mw 6.5), Greece image a segmented master fault and antithetic faults. This three-dimensional fault geometry is typical of normal fault systems mapped from outcrop or interpreted from reflection seismic data and illustrates the importance of incorporating three-dimensional fault geometry in mechanical models. Subsurface fault slip associated with the Kozani-Grevena and 1999 Hector Mine (Mw 7.1) earthquakes is modeled using a new method for slip inversion on three-dimensional fault surfaces. Incorporation of three-dimensional fault geometry improves the fit to the geodetic data while honoring aftershock distributions and surface ruptures. GPS Surveying of deformed bedding surfaces associated with normal faulting in the western Grand Canyon reveals patterns of deformation that are similar to those observed by interferometric satellite radar interferometry (InSAR) for the Kozani Grevena earthquake with a prominent down-warp in the hanging wall and a lesser up-warp in the footwall. However, deformation associated with the Kozani-Grevena earthquake extends ˜20 km from the fault surface trace, while the folds in the western Grand Canyon only extend 500 m into the footwall and 1500 m into the hanging wall. A comparison of mechanical and kinematic models illustrates advantages of mechanical models in exploring normal faulting processes including incorporation of both deformation and causative forces, and the opportunity to incorporate more complex fault geometry and constitutive properties. Elastic models with antithetic or synthetic faults or joints in association with a master

MOVPE growth and characterisation of ZnO properties for optoelectronic applications

Energy Technology Data Exchange (ETDEWEB)

Oleynik, N.

2007-03-07

In this work a new Metalorganic Vapor Phase Epitaxy (MOVPE) method was developed for the growth and doping of high-quality ZnO films. ZnO is a unique optoelectronic material for the effective light generation in the green to the UV spectral range. Optoelectronic applications of ZnO require impurity-free monocrystalline films with smooth surfaces and low concentration of the defects in the crystal lattice. At the beginning of this work only few reports on MOVPE growth of polycrystalline ZnO existed. The low quality of ZnO is attributed to the lack of an epitaxially matched substrate, and gas-phase prereactions between the Zn- and O-precursors. To achieve control over the ZnO quality, several O-precursors were tested for the growth on GaN/Si(111) or GaN/Sapphire substrates at different reactor temperatures and pressures. ZnO layers with XRD rocking curve FWHMs of the (0002) reflection of 180'' and narrow cathodoluminescence of 1.3 meV of the dominant I{sub 8} emission were synthesized using a two-step growth procedure. In this procedure, ZnO is homoepitaxially grown at high temperature using N{sub 2}O as O-precursor on a low temperature grown ZnO buffer layer using tertiary-butanol as O-precursor. p-Type doping of ZnO, which usually exhibits n-type behaviour, is very difficult. This doping asymmetry represents an issue for ZnO-based devices. Beginning from 1992, a growing number of reports have been claiming a fabrication of p-type ZnO, but, due to the missing reproducibilty, they are still questionable. Native defects, non-stoichiometry, and hydrogen are sources of n-type conductivity of ZnO. Together with a low solubility of the potential p-type dopants and deep position of impurity levels, these factors partly explain p-type doping difficulties in ZnO. However, there is no fully described mechanism of the ZnO doping asymmetry yet. In this work, NH{sub 3}, unsymmetrical dimethylhydrazine (UDMHy), diisobutylamine, and NO nitrogen precursors were studied

Optical absorption and oxygen passivation of surface states in III-nitride photonic devices

Science.gov (United States)

Rousseau, Ian; Callsen, Gordon; Jacopin, Gwénolé; Carlin, Jean-François; Butté, Raphaël; Grandjean, Nicolas

2018-03-01

III-nitride surface states are expected to impact high surface-to-volume ratio devices, such as nano- and micro-wire light-emitting diodes, transistors, and photonic integrated circuits. In this work, reversible photoinduced oxygen desorption from III-nitride microdisk resonator surfaces is shown to increase optical attenuation of whispering gallery modes by 100 cm-1 at λ = 450 nm. Comparison of photoinduced oxygen desorption in unintentionally and n+-doped microdisks suggests that the spectral changes originate from the unpinning of the surface Fermi level, likely taking place at etched nonpolar III-nitride sidewalls. An oxygen-rich surface prepared by thermal annealing results in a broadband Q improvement to state-of-the-art values exceeding 1 × 104 at 2.6 eV. Such findings emphasize the importance of optically active surface states and their passivation for future nanoscale III-nitride optoelectronic and photonic devices.

Silver nanoparticle based surface enhanced Raman scattering spectroscopy of diabetic and normal rat pancreatic tissue under near-infrared laser excitation

International Nuclear Information System (INIS)

Huang, H; Shi, H; Chen, W; Yu, Y; Lin, D; Xu, Q; Feng, S; Lin, J; Huang, Z; Li, Y; Chen, R

2013-01-01

This paper presents the use of high spatial resolution silver nanoparticle based near-infrared surface enhanced Raman scattering (SERS) from rat pancreatic tissue to obtain biochrmical information about the tissue. A high quality SERS signal from a mixture of pancreatic tissues and silver nanoparticles can be obtained within 10 s using a Renishaw micro-Raman system. Prominent SERS bands of pancreatic tissue were assigned to known molecular vibrations, such as the vibrations of DNA bases, RNA bases, proteins and lipids. Different tissue structures of diabetic and normal rat pancreatic tissues have characteristic features in SERS spectra. This exploratory study demonstrated great potential for using SERS imaging to distinguish diabetic and normal pancreatic tissues on frozen sections without using dye labeling of functionalized binding sites. (letter)

Operational parameters of an opto-electronic neural network employing fixed planar holographic interconnects

Science.gov (United States)

Keller, P. E.; Gmitro, A. F.

1993-07-01

A prototype neutral network system of multifaceted, planar interconnection holograms and opto-electronic neurons is analyzed. This analysis shows that a hologram fabricated with electron-beam lithography has the capacity to connect 6700 neuron outputs to 6700 neuron inputs, and that, the encoded synaptic weights have a precision of approximately 5 bits. Higher interconnection densities can be achieved by accepting a lower synaptic weight accuracy. For systems employing laser diodes at the outputs of the neurons, processing rates in the range of 45 to 720 trillion connections per second can potentially be achieved.

A Study on the Fatigue-Fractured Surface of Normalized SS41 Steel and M.E.F. Dual Phase Steel by an X-ray Diffraction Technique

International Nuclear Information System (INIS)

Oh, Sae Wook; Park, Young Chul; Park, Soo Young; Kim, Deug Jin; Hue, Sun Chul

1996-01-01

This study verified the relationship between fracture mechanics parameters and X-ray parameters for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel(martensite encapsulated islands of ferrite). The fatigue crack propagation test were carried out and X-ray diffraction technique was applied to fatigue fractured surface. The change in X-ray parameters(residual stress, half-value breadth) according to the depth of fatigue fractured surface were investigated. The depth of maximum plastic zone, W y , were determined on the basis of the distribution of the half-value breadth for normalized SS41 steel and that of the residual stress for M.E.F. dual phase steel. K max could be estimated by the measurement of W y

The optoelectronic properties of a photosystem I-carbon nanotube hybrid system

International Nuclear Information System (INIS)

Kaniber, Simone M; Holleitner, Alexander W; Simmel, Friedrich C; Carmeli, Itai

2009-01-01

The photoconductance properties of photosystem I (PSI) covalently bound to carbon nanotubes (CNTs) are measured. We demonstrate that the PSI forms active electronic junctions with the CNTs, enabling control of the CNTs' photoconductance by the PSI. In order to electrically contact the photoactive proteins, a cysteine mutant is generated at one end of the PSI by genetic engineering. The CNTs are covalently bound to this reactive group using carbodiimide chemistry. We detect an enhanced photoconductance signal of the hybrid material at photon wavelengths resonant to the absorption maxima of the PSI compared to non-resonant wavelengths. The measurements prove that it is feasible to integrate photosynthetic proteins into optoelectronic circuits at the nanoscale.

The optoelectronic properties of a photosystem I-carbon nanotube hybrid system

Energy Technology Data Exchange (ETDEWEB)

Kaniber, Simone M; Holleitner, Alexander W [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Simmel, Friedrich C [LMU Munich, Geschwister-Scholl-Platz 1, D-80539 Muenchen (Germany); Carmeli, Itai, E-mail: holleitner@wsi.tum.d, E-mail: itai@post.tau.ac.i [Chemistry Department and NIBN, Ben Gurion University, 84105 Be' er Sheva (Israel)

2009-08-26

The photoconductance properties of photosystem I (PSI) covalently bound to carbon nanotubes (CNTs) are measured. We demonstrate that the PSI forms active electronic junctions with the CNTs, enabling control of the CNTs' photoconductance by the PSI. In order to electrically contact the photoactive proteins, a cysteine mutant is generated at one end of the PSI by genetic engineering. The CNTs are covalently bound to this reactive group using carbodiimide chemistry. We detect an enhanced photoconductance signal of the hybrid material at photon wavelengths resonant to the absorption maxima of the PSI compared to non-resonant wavelengths. The measurements prove that it is feasible to integrate photosynthetic proteins into optoelectronic circuits at the nanoscale.

Digital optical computers at the optoelectronic computing systems center

Science.gov (United States)

Jordan, Harry F.

1991-01-01

The Digital Optical Computing Program within the National Science Foundation Engineering Research Center for Opto-electronic Computing Systems has as its specific goal research on optical computing architectures suitable for use at the highest possible speeds. The program can be targeted toward exploiting the time domain because other programs in the Center are pursuing research on parallel optical systems, exploiting optical interconnection and optical devices and materials. Using a general purpose computing architecture as the focus, we are developing design techniques, tools and architecture for operation at the speed of light limit. Experimental work is being done with the somewhat low speed components currently available but with architectures which will scale up in speed as faster devices are developed. The design algorithms and tools developed for a general purpose, stored program computer are being applied to other systems such as optimally controlled optical communication networks.

Critical difference between optoelectronic properties of α- and β-SnWO4semiconductors: A DFT/HSE06 and experimental investigation

KAUST Repository

Harb, Moussab; Ziani, Ahmed; Takanabe, Kazuhiro

2016-01-01

The optoelectronic properties of β-SnWO4 are investigated in details using experiments on thin film generated by rapid quenching and the first-principles quantum calculations based on the density functional theory (DFT, including the perturbation

An Opto-Electronic Sensor for Detecting Soil Microarthropods and Estimating Their Size in Field Conditions

Directory of Open Access Journals (Sweden)

Csongor I. Gedeon

2017-08-01

Full Text Available Methods to estimate density of soil-dwelling arthropods efficiently, accurately and continuously are critical for investigating soil biological activity and evaluating soil management practices. Soil-dwelling arthropods are currently monitored manually. This method is invasive, and time- and labor-consuming. Here we describe an infrared opto-electronic sensor for detection of soil microarthropods in the size range of 0.4–10 mm. The sensor is built in a novel microarthropod trap designed for field conditions. It allows automated, on-line, in situ detection and body length estimation of soil microarthropods. In the opto-electronic sensor the light source is an infrared LED. Two plano-convex optical lenses are placed along the virtual optical axis. One lens on the receiver side is placed between the observation space at 0.5–1 times its focal length from the sensor, and another emitter side lens is placed between the observation space and the light source in the same way. This paper describes the setup and operating mechanism of the sensor and the control unit, and through basic tests it demonstrates its potential in automated detection of soil microarthropods. The sensor may be used for monitoring activities, especially for remote observation activities in soil and insect ecology or pest control.

Standardized uptake values of fluorine-18 fluorodeoxyglucose: the value of different normalization procedures

International Nuclear Information System (INIS)

Schomburg, A.; Bender, H.; Reichel, C.; Sommer, T.; Ruhlmann, J.; Kozak, B.; Biersack, H.J.

1996-01-01

While the evident advantages of absolute metabolic rate determinations cannot be equalled by static image analysis of fluorine-18 fluorodexyglucose positron emission tomographic (FDG PET) studies, various algorithms for the normalization of static FDG uptake values have been proposed. This study was performed to compare different normalization procedures in terms of dependency on individual patient characteristics. Standardized FDG uptake values (SUVs) were calculated for liver and lung tissue in 126 patients studied with whole-body FDG PET. Uptake values were normalized for total body weight, lean body mass and body surface area. Ranges, means, medians, standard deviations and variation coefficients of these SUV parameters were calculated and their interdependency with total body weight, lean body mass, body surface area, patient height and blood sugar levels was calculated by means of regression analysis. Standardized FDG uptake values normalized for body surface area were clearly superior to SUV parameters normalized for total body weight or lean body mass. Variation and correlation coefficients of body surface area-normalized uptake values were minimal when compared with SUV parameters derived from the other normalization procedures. Normalization for total body weight resulted in uptake values still dependent on body weight and blood sugar levels, while normalization for lean body mass did not eliminate the positive correlation with lean body mass and patient height. It is concluded that normalization of FDG uptake values for body surface area is less dependent on the individual patient characteristics than are FDG uptake values normalized for other parameters, and therefore appears to be preferable for FDG PET studies in oncology. (orig.)

Functional Carbon Nanocomposite, Optoelectronic, and Catalytic Coatings

Science.gov (United States)

Liang, Yu Teng

Over the past couple decades, fundamental research into carbon nanomaterials has produced a steady stream of groundbreaking physical science. Their record setting mechanical strength, chemical stability, and optoelectronic performance have fueled many optimistic claims regarding the breadth and pace of carbon nanotube and graphene integration. However, present synthetic, processing, and economic constraints have precluded these materials from many practical device applications. To overcome these limitations, novel synthetic techniques, processing methodologies, device geometries, and mechanistic insight were developed in this dissertation. The resulting advancements in material production and composite device performance have brought carbon nanomaterials ever closer to commercial implementation. For improved materials processing, vacuum co-deposition was first demonstrated as viable technique for forming carbon nanocomposite films without property distorting covalent modifications. Co-deposited nanoparticle, carbon nanotube, and graphene composite films enabled rapid device prototyping and compositional optimization. Cellulosic polymer stabilizers were then shown to be highly effective carbon nanomaterial dispersants, improving graphene production yields by two orders of magnitude in common organic solvents. By exploiting polarity interactions, iterative solvent exchange was used to further increase carbon nanomaterial dispersion concentrations by an additional order of magnitude, yielding concentrated inks. On top of their low causticity, these cellulosic nanomaterial inks have highly tunable viscosities, excellent film forming capacity, and outstanding thermal stability. These processing characteristics enable the efficient scaling of carbon nanomaterial coatings and device production using existing roll-to-roll fabrication techniques. Utilizing these process improvements, high-performance gas sensing, energy storage, transparent conductor, and photocatalytic

Opto-electronic characterization of polycrystalline CuInS2 and Cu(In,Ga)S2 absorber layers by photoluminescence

International Nuclear Information System (INIS)

Heidemann, Florian

2011-01-01

Photoluminescence (PL) is an established method to characterize the optoelectronic properties of solar cell absorber layers. With the help of Planck's generalized law it is in principle possible to determine the quasi-Fermi level splitting - which is the upper limit of the open circuit voltage V oc - and the absorption coefficient of a solar cell before its actual completion. For large-scale measurements (mm/cm regime) this is valid for absorber layers with lateral homogeneous properties, however it is not directly transferable to polycrystalline semiconductors due to laterally fluctuating opto-electronic and structural parameters. The lateral fluctuations in opto-electronic properties of polycrystalline Cu(In 1-ξ Ga ξ )S 2 have been analyzed (e.g. with respect to fluctuations in quasi-Fermi level splitting, optical band-gap and sub band-gap absorbance) by measuring laterally and spectrally resolved PL on the μm-scale and providing the transition towards macroscopic PL measurements on the mm-scale. To give a comprehensive characterization, surface roughness and optical properties have been studied and methods for feature extraction have been applied. On the microscopic scale variations in the quasi-Fermi level splitting Δ x,y E Fnp of about 38 meV (CuInS 2 ) and 53 meV (Cu(In,Ga)S 2 ) have been found. From local absorbance spectra extracted from PL measurements on Cu(In,Ga)S 2 fluctuations in the optical band-gap E opt with a full width at half maximum of FWHM E opt ∼80 meV could be extracted, whereas band-gap fluctuations in CuInS 2 are found to be negligible. Thus band-gap fluctuations seem to be mainly caused by a varying gallium (Ga) content. Furthermore, regions with higher E opt and with it a potential higher Ga content, show a higher quasi-Fermi level splitting. As a major limiting factor for the local quasi-Fermi level splitting E Fnp the local density of deep defects could be identified. Due to low luminescence yields of Cu(In 1-ξ Ga ξ )S 2 under

[Experimental studies on the diffusion of excitation on the right ventricular surface in the dog, during normal and stimulated beats].

Science.gov (United States)

Arisi, G; Macchi, E; Baruffi, S; Musso, E; Spaggiari, S; Stilli, D; Taccardi, B

1982-01-01

Previous work on the spread of excitation on the dog's ventricular surface enabled us to locate up to 30 breakthrough points (BKTPs) where excitation reaches the ventricular surface. In particular the equipotential contour maps enabled us to detect 3 to 5 BKTPs on the anterior right ventricular surface, near the a-v groove when a large part of ventricular surface was still at rest. With a view to investigating the mechanism underlying the early excitation of these basal regions, we stimulated the heart at several right ventricular BKTPs and in other points located at a distance from the BKTPs. The instantaneous equipotential maps showed that after stimulation most right ventricular BKTPs remained in the same position as observed the normal beats. The early appearance of epicardial wavefronts in the basal region and generally in other areas of the right ventricle was attributed to the rapid propagation of excitation waves through the Purkinje network, probably associated to a short transmural crossing time, due to a local thinness of the ventricular wall.

Polynomial law for controlling the generation of n-scroll chaotic attractors in an optoelectronic delayed oscillator

Energy Technology Data Exchange (ETDEWEB)

Márquez, Bicky A., E-mail: bmarquez@ivic.gob.ve; Suárez-Vargas, José J., E-mail: jjsuarez@ivic.gob.ve; Ramírez, Javier A. [Centro de Física, Instituto Venezolano de Investigaciones Científicas, km. 11 Carretera Panamericana, Caracas 1020-A (Venezuela, Bolivarian Republic of)

2014-09-01

Controlled transitions between a hierarchy of n-scroll attractors are investigated in a nonlinear optoelectronic oscillator. Using the system's feedback strength as a control parameter, it is shown experimentally the transition from Van der Pol-like attractors to 6-scroll, but in general, this scheme can produce an arbitrary number of scrolls. The complexity of every state is characterized by Lyapunov exponents and autocorrelation coefficients.

Flexible Synthetic Semiconductor Applied in Optoelectronic Organic Sensor

Directory of Open Access Journals (Sweden)

Andre F. S. Guedes

2017-06-01

Full Text Available The synthesis and application of new nanostructured organic materials, for the development of technology based on organic devices, have taken great interest from the scientific community. The greatest interest in studying organic semiconductor materials has been connected to its already known potential applications, such as: batteries, organic solar cells, flexible organic solar cells, organic light emitting diodes, organic sensors and others. Phototherapy makes use of different radiation sources, and the treatment of hyperbilirubinemia the most common therapeutic intervention occurs in the neonatal period. In this work we developed an organic optoelectronic sensor capable of detecting and determining the radiation dose rate emitted by the radiation source of neonatal phototherapy equipment. The sensors were developed using optically transparent substrate with Nanostructured thin film layers of Poly(9-Vinylcarbazole covered by a layer of Poly(P-Phenylene Vinylene. The samples were characterized by UV-Vis Spectroscopy, Electrical Measurements and SEM. With the results obtained from this study can be developed dosimeters organics to the neonatal phototherapy equipment.

Inflammatory Cytokine Tumor Necrosis Factor α Confers Precancerous Phenotype in an Organoid Model of Normal Human Ovarian Surface Epithelial Cells

Directory of Open Access Journals (Sweden)

Joseph Kwong

2009-06-01

Full Text Available In this study, we established an in vitro organoid model of normal human ovarian surface epithelial (HOSE cells. The spheroids of these normal HOSE cells resembled epithelial inclusion cysts in human ovarian cortex, which are the cells of origin of ovarian epithelial tumor. Because there are strong correlations between chronic inflammation and the incidence of ovarian cancer, we used the organoid model to test whether protumor inflammatory cytokine tumor necrosis factor α would induce malignant phenotype in normal HOSE cells. Prolonged treatment of tumor necrosis factor α induced phenotypic changes of the HOSE spheroids, which exhibited the characteristics of precancerous lesions of ovarian epithelial tumors, including reinitiation of cell proliferation, structural disorganization, epithelial stratification, loss of epithelial polarity, degradation of basement membrane, cell invasion, and overexpression of ovarian cancer markers. The result of this study provides not only an evidence supporting the link between chronic inflammation and ovarian cancer formation but also a relevant and novel in vitro model for studying of early events of ovarian cancer.

Recent Developments of an Opto-Electronic THz Spectrometer for High-Resolution Spectroscopy

Directory of Open Access Journals (Sweden)

Guillaume Ducournau

2009-11-01

Full Text Available A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined and the insensitivity of this technique to aerosols is demonstrated by the analysis of cigarette smoke. A multiple pass sample cell has been used to obtain a sensitivity improvement allowing transitions of the volatile organic compounds to be observed. A solution to the frequency metrology is presented and promises to yield accurate molecular line center measurements.

Displacement measurement using an optoelectronic oscillator with an intra-loop Michelson interferometer.

Science.gov (United States)

Lee, Jehyun; Park, Sooyoung; Seo, Dae Han; Yim, Sin Hyuk; Yoon, Seokchan; Cho, D

2016-09-19

We report on measurement of small displacements with sub-nanometer precision using an optoelectronic oscillator (OEO) with an intra-loop Michelson interferometer. In comparison with conventional homodyne and heterodyne detection methods, where displacement appears as a power change or a phase shift, respectively, in the OEO detection, the displacement produces a shift in the oscillation frequency. In comparison with typical OEO sensors, where the frequency shift is proportional to the OEO oscillation frequency in radio-frequency domain, the frequency shift in our method with an intra-loop interferometer is proportional to an optical frequency. We constructed a hybrid apparatus and compared characteristics of the OEO and heterodyne detection methods.

Surface structures of normal paraffins and cyclohexane monolayers and thin crystals grown on the (111) crystal face of platinum. A low-energy electron diffraction study

International Nuclear Information System (INIS)

Firment, L.E.; Somorjai, G.A.

1977-01-01

The surfaces of the normal paraffins (C 3 --C 8 ) and cyclohexane have been studied using low-energy electron diffraction (LEED). The samples were prepared by vapor deposition on the (111) face of a platinum single crystal in ultrahigh vacuum, and were studied both as thick films and as adsorbed monolayers. These molecules form ordered monolayers on the clean metal surface in the temperature range 100--220 K and at a vapor flux corresponding to 10 -7 Torr. In the adsorbed monolayers of the normal paraffins (C 4 --C 8 ), the molecules lie with their chain axes parallel to the Pt surface and Pt[110]. The paraffin monolayer structures undergo order--disorder transitions as a function of temperature. Multilayers condensed upon the ordered monolayers maintained the same orientation and packing as found in the monolayers. The surface structures of the growing organic crystals do not corresond to planes in their reported bulk crystal structures and are evidence for epitaxial growth of pseudomorphic crystal forms. Multilayers of n-octane and n-heptane condensed upon disordered monolayers have also grown with the (001) plane of the triclinic bulk crystal structures parallel to the surface. n-Butane has three monolayer structures on Pt(111) and one of the three is maintained during growth of the crystal. Cyclohexane forms an ordered monolayer, upon which a multilayer of cyclohexane grows exhibiting the (001) surface orientation of the monoclinic bulk crystal structure. Surface structures of saturated hydrocarbons are found to be very susceptible to electron beam induced damage. Surface charging interferes with LEED only at sample thicknesses greater than 200 A

Novel transparent high-performance AgNWs/ZnO electrodes prepared on unconventional substrates with 3D structured surfaces

Science.gov (United States)

Lan, Wei; Yang, Zhiwei; Zhang, Yue; Wei, Yupeng; Wang, Pengxiang; Abas, Asim; Tang, Guomei; Zhang, Xuetao; Wang, Junya; Xie, Erqing

2018-03-01

With the development of optoelectronic devices with three-dimensional (3D) structured surfaces, transparent electrodes that can be deposited on non-plane substrates have become increasingly important. In this paper, novel transparent silver nanowire (AgNWs)/ZnO film electrodes were uniformly prepared on treated 3D glass and PET substrates with a combination of spin-coating and heat-welding. The AgNWs/ZnO films show a transmittance of ∼88% and a sheet resistance of ∼10 Ω/sq. They are comparable with commercial ITO films. Furthermore, only a small in-plane resistance variation of ∼1 Ω/sq was measured using four-point probe mapping in films with a 10 cm × 10 cm area. These results confirm that these novel film electrodes are very uniform. Both electrical resistance and optical transmittance of the films remain mostly intact after 1000 bending cycles and tape peeling-tests with 10 cycles. The films show high thermal stability for more than one month at 80 °C. The strategy provides a new route for the design and fabrication of optoelectronic devices with 3D structured surfaces.

Influence of pH on optoelectronic properties of zinc sulphide thin films prepared using hydrothermal and spin coating method

Science.gov (United States)

Choudapur, V. H.; Bennal, A. S.; Raju, A. B.

2018-04-01

The ZnS nanomaterial is synthesized by hydrothermal method under optimized conditions using Zinc acetate and sodium sulphide as precursors. The Zinc Sulphide thin films are obtained by simple spin coating method with high optical transmittance. The prepared thin films are adhesive and uniform. The x-ray diffraction analysis showed that the films are polycrystalline in cubic phase with the preferred orientation along (111) direction. Current-voltage curves were recorded at room temperature using Keithley 617 programmable electrometer and conductivity is calculated for the film coated on ITO by two probe method. The pH of the solution is varied by using ammonia and hydrochloric acid. The comparative studies of effect of pH on the morphology, crystallanity and optoelectronic properties of the films are studied. It is observed that the pH of the solution has large influence on optoelectronic properties. The thin film prepared with neutral pH has higher crystallanity, bandgap and conductivity as compared to the samples prepared in acidic or basic solutions.

Optoelectronic properties of doped hydrothermal ZnO thin films

KAUST Repository

Mughal, Asad J.

2017-03-10

Group III impurity doped ZnO thin films were deposited on MgAl2O3 substrates using a simple low temperature two-step deposition method involving atomic layer deposition and hydrothermal epitaxy. Films with varying concentrations of either Al, Ga, or In were evaluated for their optoelectronic properties. Inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of dopants within the ZnO films. While Al and Ga-doped films showed linear incorporation rates with the addition of precursors salts in the hydrothermal growth solution, In-doped films were shown to saturate at relatively low concentrations. It was found that Ga-doped films showed the best performance in terms of electrical resistivity and optical absorbance when compared to those doped with In or Al, with a resistivity as low as 1.9 mΩ cm and an optical absorption coefficient of 441 cm−1 at 450 nm.

Normalization constraint for variational bounds on fluid permeability

International Nuclear Information System (INIS)

Berryman, J.G.; Milton, G.W.

1985-01-01

A careful reexamination of the formulation of Prager's original variational principle for viscous flow through porous media has uncovered a subtle error in the normalization constraint on the trial functions. Although a certain surface integral of the true pressure field over the internal surface area always vanishes for isotropic materials, the corresponding surface integral for a given trial pressure field does not necessarily vanish but has nevertheless been previously neglected in the normalization. When this error is corrected, the form of the variational estimate is actually simpler than before and furthermore the resulting bounds have been shown to improve when the constant trial functions are used in either the two-point or three-point bounds

Normal gravity field in relativistic geodesy

Science.gov (United States)

Kopeikin, Sergei; Vlasov, Igor; Han, Wen-Biao

2018-02-01

Modern geodesy is subject to a dramatic change from the Newtonian paradigm to Einstein's theory of general relativity. This is motivated by the ongoing advance in development of quantum sensors for applications in geodesy including quantum gravimeters and gradientometers, atomic clocks and fiber optics for making ultra-precise measurements of the geoid and multipolar structure of the Earth's gravitational field. At the same time, very long baseline interferometry, satellite laser ranging, and global navigation satellite systems have achieved an unprecedented level of accuracy in measuring 3-d coordinates of the reference points of the International Terrestrial Reference Frame and the world height system. The main geodetic reference standard to which gravimetric measurements of the of Earth's gravitational field are referred is a normal gravity field represented in the Newtonian gravity by the field of a uniformly rotating, homogeneous Maclaurin ellipsoid of which mass and quadrupole momentum are equal to the total mass and (tide-free) quadrupole moment of Earth's gravitational field. The present paper extends the concept of the normal gravity field from the Newtonian theory to the realm of general relativity. We focus our attention on the calculation of the post-Newtonian approximation of the normal field that is sufficient for current and near-future practical applications. We show that in general relativity the level surface of homogeneous and uniformly rotating fluid is no longer described by the Maclaurin ellipsoid in the most general case but represents an axisymmetric spheroid of the fourth order with respect to the geodetic Cartesian coordinates. At the same time, admitting a post-Newtonian inhomogeneity of the mass density in the form of concentric elliptical shells allows one to preserve the level surface of the fluid as an exact ellipsoid of rotation. We parametrize the mass density distribution and the level surface with two parameters which are

Generating a normalized geometric liver model with warping

International Nuclear Information System (INIS)

Boes, J.L.; Weymouth, T.E.; Meyer, C.R.; Quint, L.E.; Bland, P.H.; Bookstein, F.L.

1990-01-01

This paper reports on the automated determination of the liver surface in abdominal CT scans for radiation treatment, surgery planning, and anatomic visualization. The normalized geometric model of the liver is generated by averaging registered outlines from a set of 15 studies of normal liver. The outlines have been registered with the use of thin-plate spline warping based on a set of five homologous landmarks. Thus, the model consists of an average of the surface and a set of five anatomic landmarks. The accuracy of the model is measured against both the set of studies used in model generation and an alternate set of 15 normal studies with use of, as an error measure, the ratio of nonoverlapping model and study volume to total model volume

Silver nanowire/polyaniline composite transparent electrode with improved surface properties

International Nuclear Information System (INIS)

Kumar, A.B.V. Kiran; Jiang, Jianwei; Bae, Chang Wan; Seo, Dong Min; Piao, Longhai; Kim, Sang-Ho

2014-01-01

Highlights: • AgNWs/PANI transparent electrode was prepared by layer-by-layer coating method. • The surface roughness of the electrode reached to 6.5 nm (root mean square). • The electrode had reasonable sheet resistance (25 Ω/□) and transmittance (83.5%). - Abstract: Silver nanowires (AgNWs) are as potential candidates to replace indium tin oxide (ITO) in transparent electrodes because of their preferred conducting and optical properties. However, their rough surface properties are not favorable for the fabrication of optoelectronic devices, such as displays and thin-film solar cells. In the present investigation, AgNWs/polyaniline composite transparent electrodes with better surface properties were successfully prepared. AgNWs were incorporated into polyaniline:polystyrene sulfonate (PANI:PSS) by layer-by-layer coating and mechanical pressing. PANI:PSS decreased the surface roughness of the AgNWs electrode by filling the gap of the random AgNWs network. The transparent composite electrode had decreased surface roughness (root mean square 6.5 nm) with reasonable sheet resistance (25 Ω/□) and transmittance (83.5%)

Silicon opto-electronic wavelength tracker based on an asymmetric 2x3 Mach-Zehnder Interferometer

OpenAIRE

Doménech Gómez, José David; Sanchez Fandiño, Javier Antonio; Gargallo Jaquotot, Bernardo Andrés; Baños Lopez, Rocio; Muñoz Muñoz, Pascual

2014-01-01

In this paper we report on the experimental demonstration of a Silicon-on-Insulator opto-electronic wavelength tracker for the optical telecommunication C-band. The device consist of a 2x3 Mach-Zehnder Interferometer (MZI) with 10 pm resolution and photo-detectors integrated on the same chip. The MZI is built interconnecting two Multimode Interference (MMI) couplers with two waveguides whose length difference is 56 mm. The first MMI has a coupling ratio of 95:05 to com...

Sputtering of a silicon surface: Preferential sputtering of surface impurities

Czech Academy of Sciences Publication Activity Database

Nietiadi, M.L.; Rosandi, Y.; Lorinčík, Jan; Urbassek, H.M.

-, č. 303 (2013), s. 205-208 ISSN 0168-583X Institutional support: RVO:67985882 Keywords : Sputtering * Molecular dynamics * SIMS Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.186, year: 2013

Ligand removal and photo-activation of CsPbBr3 quantum dots for enhanced optoelectronic devices.

Science.gov (United States)

Moyen, Eric; Kanwat, Anil; Cho, Sinyoung; Jun, Haeyeon; Aad, Roy; Jang, Jin

2018-05-10

Perovskite quantum dots have recently emerged as a promising light source for optoelectronic applications. However, integrating them into devices while preserving their outstanding optical properties remains challenging. Due to their ionic nature, perovskite quantum dots are extremely sensitive and degrade on applying the simplest processes. To maintain their colloidal stability, they are surrounded by organic ligands; these prevent efficient charge carrier injection in devices and have to be removed. Here we report on a simple method, where a moderate thermal process followed by exposure to UV in air can efficiently remove ligands and increase the photo-luminescence of the room temperature synthesized perovskite quantum dot thin films. Annealing is accompanied by a red shift of the emission wavelength, usually attributed to the coalescence and irreversible degradation of the quantum dots. We show that it is actually related to the relaxation of the quantum dots upon the ligand removal, without the creation of non-radiative recombining defects. The quantum dot surface, as devoid of ligands, is subsequently photo-oxidized and smoothened upon exposure to UV in air, which drastically enhances their photo-luminescence. This adequate combination of treatments improves by more than an order of magnitude the performances of perovskite quantum dot light emitting diodes.

Chemical synthesis and characterization of CdSe thin films deposited by SILAR technique for optoelectronic applications

Directory of Open Access Journals (Sweden)

K.B. Chaudhari

2016-12-01

Full Text Available CdSe thin films were deposited on the glass substrate by successive ionic layer adsorption and reaction (SILAR method. Different sets of the film are prepared by changing the number of immersion cycles as 30, 40, 50 and 60. Further the effect of a number of immersion cycles on the characteristic structural, morphological, optical and electrical properties of the films are studied. The XRD studies revealed that the deposited films showed hexagonal structure with most prominent reflection along (1 0 1 plane. Moreover, the peak intensity of (1 0 1 plane is found to be increased as the number of immersion cycles is increased. All the thin films look relatively smooth and homogeneous covering the entire surface area in FESEM image. Optical properties of the CdSe thin films for a different number of immersion cycles were studied, which indicates that the absorbance increases with the increase in the immersion cycles. Furthermore, the optical band-gap in conjunction with the electrical resistivity was found to get decreased with increase in the immersion cycles. A good correlation between the number of immersion cycles and the physical properties indicates a simple method to manipulate the CdSe material properties for optoelectronic applications.

Effects of Packing Structure on the Optoelectronic and Charge Transport Properties in Poly(9,9-di-n-octylfluorene-alt-benzothiadiazole)

DEFF Research Database (Denmark)

Donley, C.L.; Zaumseil, J.; Andreasen, Jens Wenzel

2005-01-01

on the optoelectronic and charge transport properties of these films. A model based on quantum chemical calculations, wide-angle X-ray scattering, atomic force microscopy, Raman spectroscopy, photoluminescence, and electron mobility measurements was developed to describe the restructuring of the polymer film...

The Electrical and Optical Properties of Organometal Halide Perovskites Relevant to Optoelectronic Performance

KAUST Repository

Adinolfi, Valerio

2017-10-12

Organometal halide perovskites are under intense study for use in optoelectronics. Methylammonium and formamidinium lead iodide show impressive performance as photovoltaic materials; a premise that has spurred investigations into light-emitting devices and photodetectors. Herein, the optical and electrical material properties of organometal halide perovskites are reviewed. An overview is given on how the material composition and morphology are tied to these properties, and how these properties ultimately affect device performance. Material attributes and techniques used to estimate them are analyzed for different perovskite materials, with a particular focus on the bandgap, mobility, diffusion length, carrier lifetime, and trap-state density.

Active stabilization of a rapidly chirped laser by an optoelectronic digital servo-loop control.

Science.gov (United States)

Gorju, G; Jucha, A; Jain, A; Crozatier, V; Lorgeré, I; Le Gouët, J-L; Bretenaker, F; Colice, M

2007-03-01

We propose and demonstrate a novel active stabilization scheme for wide and fast frequency chirps. The system measures the laser instantaneous frequency deviation from a perfectly linear chirp, thanks to a digital phase detection process, and provides an error signal that is used to servo-loop control the chirped laser. This way, the frequency errors affecting a laser scan over 10 GHz on the millisecond timescale are drastically reduced below 100 kHz. This active optoelectronic digital servo-loop control opens new and interesting perspectives in fields where rapidly chirped lasers are crucial.

Reconstructions of the sulfur-passivated InSb (100) surface

Energy Technology Data Exchange (ETDEWEB)

Ciochoń, Piotr, E-mail: piotr.ciochon@doctoral.uj.edu.pl; Olszowska, Natalia; Wróbel, Sonia; Kołodziej, Jacek

2017-04-01

Highlights: • Two new surface reconstructions of a S-passivated InSb (001) surface are reported. • The reconstructions are obtained through partial loss of surface sulfur. • They are characterized by the thickness of ∼4 Å and good crystallographic ordering. • The reconstructions provide adequate electronic passivation of the surface. - Abstract: We have studied the properties of the InSb (100) surface passivated with sulfur dimers emitted by the solid-state electrochemical cell in ultra-high vacuum. Annealing the passivated surface in the temperature equal to T = 326 °C led to the formation of the c(4 × 8) surface reconstruction, while increasing the temperature to T = 348 °C resulted in the transition to c(4 × 12) reconstruction. To the best of our knowledge these reconstructions have not been reported to date and are characterized by the exceptionally good crystallographic order. XPS studies revealed that there are at least 4 different chemical species of sulfur present on the surface and the estimated thickness of the sulfur layers is equal to around 4 Å. The surface reconstructions are characterized by the lowered intensity of the surface electronic states and resonances near the Fermi level, compared to the clean InSb surface, making them potentially very useful for the fabrication of InSb-based electronic and optoelectronic devices.

Normalization of satellite imagery

Science.gov (United States)

Kim, Hongsuk H.; Elman, Gregory C.

1990-01-01

Sets of Thematic Mapper (TM) imagery taken over the Washington, DC metropolitan area during the months of November, March and May were converted into a form of ground reflectance imagery. This conversion was accomplished by adjusting the incident sunlight and view angles and by applying a pixel-by-pixel correction for atmospheric effects. Seasonal color changes of the area can be better observed when such normalization is applied to space imagery taken in time series. In normalized imagery, the grey scale depicts variations in surface reflectance and tonal signature of multi-band color imagery can be directly interpreted for quantitative information of the target.

Investigations of DC power supplies with optoelectronic transducers and RF energy converters

Science.gov (United States)

Guzowski, B.; Gozdur, R.; Bernacki, L.; Lakomski, M.

2016-04-01

Fiber Distribution Cabinets (FDC) monitoring systems are increasingly popular. However it is difficult to realize such system in passive FDC, due to lack of source of power supply. In this paper investigation of four different DC power supplies with optoelectronic transducers is described. Two converters: photovoltaic power converter and PIN photodiode can convert the light transmitted through the optical fiber to electric energy. Solar cell and antenna RF-PCB are also tested. Results presented in this paper clearly demonstrate that it is possible to build monitoring system in passive FDC. During the tests maximum obtained output power was 11 mW. However all converters provided enough power to excite 32-bit microcontroller with ARM-cores and digital thermometer.

Brownian motion properties of optoelectronic random bit generators based on laser chaos.

Science.gov (United States)

Li, Pu; Yi, Xiaogang; Liu, Xianglian; Wang, Yuncai; Wang, Yongge

2016-07-11

The nondeterministic property of the optoelectronic random bit generator (RBG) based on laser chaos are experimentally analyzed from two aspects of the central limit theorem and law of iterated logarithm. The random bits are extracted from an optical feedback chaotic laser diode using a multi-bit extraction technique in the electrical domain. Our experimental results demonstrate that the generated random bits have no statistical distance from the Brownian motion, besides that they can pass the state-of-the-art industry-benchmark statistical test suite (NIST SP800-22). All of them give a mathematically provable evidence that the ultrafast random bit generator based on laser chaos can be used as a nondeterministic random bit source.

Hybrid Doping of Few-Layer Graphene via a Combination of Intercalation and Surface Doping

KAUST Repository

Mansour, Ahmed

2017-05-23

Surface molecular doping of graphene has been shown to modify its work function and increase its conductivity. However, the associated shifts in work function and increases in carrier concentration are highly coupled and limited by the surface coverage of dopant molecules on graphene. Here we show that few-layer graphene (FLG) can be doped using a hybrid approach, effectively combining surface doping by larger (metal-)organic molecules, while smaller molecules, such as Br2 and FeCl3, intercalate into the bulk. Intercalation tunes the carrier concentration more effectively, whereas surface doping of intercalated FLG can be used to tune its work function without reducing the carrier mobility. This multi-modal doping approach yields a very high carrier density and tunable work function for FLG, demonstrating a new versatile platform for fabricating graphene-based contacts for electronic, optoelectronic and photovoltaic applications.

Hybrid Doping of Few-Layer Graphene via a Combination of Intercalation and Surface Doping

KAUST Repository

Mansour, Ahmed; Kirmani, Ahmad R.; Barlow, Stephen; Marder, Seth R.; Amassian, Aram

2017-01-01

Surface molecular doping of graphene has been shown to modify its work function and increase its conductivity. However, the associated shifts in work function and increases in carrier concentration are highly coupled and limited by the surface coverage of dopant molecules on graphene. Here we show that few-layer graphene (FLG) can be doped using a hybrid approach, effectively combining surface doping by larger (metal-)organic molecules, while smaller molecules, such as Br2 and FeCl3, intercalate into the bulk. Intercalation tunes the carrier concentration more effectively, whereas surface doping of intercalated FLG can be used to tune its work function without reducing the carrier mobility. This multi-modal doping approach yields a very high carrier density and tunable work function for FLG, demonstrating a new versatile platform for fabricating graphene-based contacts for electronic, optoelectronic and photovoltaic applications.

Colloidal CuInSe2 nanocrystals thin films of low surface roughness

International Nuclear Information System (INIS)

Kergommeaux, Antoine de; Fiore, Angela; Faure-Vincent, Jérôme; Pron, Adam; Reiss, Peter

2013-01-01

Thin-film processing of colloidal semiconductor nanocrystals (NCs) is a prerequisite for their use in (opto-)electronic devices. The commonly used spin-coating is highly materials consuming as the overwhelming amount of deposited matter is ejected from the substrate during the spinning process. Also, the well-known dip-coating and drop-casting procedures present disadvantages in terms of the surface roughness and control of the film thickness. We show that the doctor blade technique is an efficient method for preparing nanocrystal films of controlled thickness and low surface roughness. In particular, by optimizing the deposition conditions, smooth and pinhole-free films of 11 nm CuInSe 2 NCs have been obtained exhibiting a surface roughness of 13 nm root mean square (rms) for a 350 nm thick film, and less than 4 nm rms for a 75 nm thick film. (paper)

Localized surface phonon polariton resonances in polar gallium nitride

Energy Technology Data Exchange (ETDEWEB)

Feng, Kaijun, E-mail: kfeng@nd.edu; Islam, S. M.; Verma, Jai; Hoffman, Anthony J. [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Streyer, William; Wasserman, Daniel [Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States); Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14850 (United States)

2015-08-24

We demonstrate the excitation of localized surface phonon polaritons in an array of sub-diffraction pucks fabricated in an epitaxial layer of gallium nitride (GaN) on a silicon carbide (SiC) substrate. The array is characterized via polarization- and angle-dependent reflection spectroscopy in the mid-infrared, and coupling to several localized modes is observed in the GaN Reststrahlen band (13.4–18.0 μm). The same structure is simulated using finite element methods and the charge density of the modes are studied; transverse dipole modes are identified for the transverse electric and magnetic polarizations and a quadrupole mode is identified for the transverse magnetic polarization. The measured mid-infrared spectrum agrees well with numerically simulated spectra. This work could enable optoelectronic structures and devices that support surface modes at mid- and far-infrared wavelengths.

Hydrogen-Bonded Organic Semiconductor Micro- And Nanocrystals: From Colloidal Syntheses to (Opto-)Electronic Devices

Science.gov (United States)

2014-01-01

Organic pigments such as indigos, quinacridones, and phthalocyanines are widely produced industrially as colorants for everyday products as various as cosmetics and printing inks. Herein we introduce a general procedure to transform commercially available insoluble microcrystalline pigment powders into colloidal solutions of variously sized and shaped semiconductor micro- and nanocrystals. The synthesis is based on the transformation of the pigments into soluble dyes by introducing transient protecting groups on the secondary amine moieties, followed by controlled deprotection in solution. Three deprotection methods are demonstrated: thermal cleavage, acid-catalyzed deprotection, and amine-induced deprotection. During these processes, ligands are introduced to afford colloidal stability and to provide dedicated surface functionality and for size and shape control. The resulting micro- and nanocrystals exhibit a wide range of optical absorption and photoluminescence over spectral regions from the visible to the near-infrared. Due to excellent colloidal solubility offered by the ligands, the achieved organic nanocrystals are suitable for solution processing of (opto)electronic devices. As examples, phthalocyanine nanowire transistors as well as quinacridone nanocrystal photodetectors, with photoresponsivity values by far outperforming those of vacuum deposited reference samples, are demonstrated. The high responsivity is enabled by photoinduced charge transfer between the nanocrystals and the directly attached electron-accepting vitamin B2 ligands. The semiconducting nanocrystals described here offer a cheap, nontoxic, and environmentally friendly alternative to inorganic nanocrystals as well as a new paradigm for obtaining organic semiconductor materials from commercial colorants. PMID:25253644

A self-starting hybrid optoelectronic oscillator generating ultra low jitter 10-GHz optical pulses and low phase noise electrical signals

DEFF Research Database (Denmark)

Lasri, J.; Bilenca, A.; Dahan, D.

2002-01-01

In this letter, we describe a self-starting optical pulse source generating ultra low noise 15-ps-wide pulses at 10 GHz. It is based on a hybrid optoelectronic oscillator comprising a fiber extended cavity mode-locked diode laser which injection locks a self-oscillating heterojunction bipolar...

Optoelectronic devices, low temperature preparation methods, and improved electron transport layers

KAUST Repository

Eita, Mohamed S.

2016-08-04

An optoelectronic device such as a photovoltaic device which has at least one layer, such as an electron transport layer, which comprises a plurality of alternating, oppositely charged layers including metal oxide layers. The metal oxide can be zinc oxide. The plurality of layers can be prepared by layer-by-layer processing in which alternating layers are built up step-by-step due to electrostatic attraction. The efficiency of the device can be increased by this processing method compared to a comparable method like sputtering. The number of layers can be controlled to improve device efficiency. Aqueous solutions can be used which is environmentally friendly. Annealing can be avoided. A quantum dot layer can be used next to the metal oxide layer to form a quantum dot heterojunction solar device.

Complete diagnostics of pyroactive structures for smart systems of optoelectronics

Science.gov (United States)

Bravina, Svetlana L.; Morozovsky, Nicholas V.

1998-04-01

The results of study of pyroelectric phenomena in ferroelectric materials for evidence of the possibility to embody the functions promising for creation of smart systems for optoelectronic applications are presented. Designing such systems requires the development of methods for non- destructive complete diagnostics preferably by developing the self-diagnostic ability inherent in materials with the features of smart/intelligent ones. The complex method of complete non-destructive qualification of pyroactive materials based on the method of dynamic photopyroelectric effect allows the determination of pyroelectric, piezoelectric, ferroelectric, dielectric and thermophysical characteristics. The measuring system which allows the study of these characteristics and also memory effects, switching effects, fatigue and degradation process, self-repair process and others is presented. Sample pyroactive system with increased intelligence, such as systems with built-in adaptive controllable domain structure promising for functional optics are developed and peculiarities of their characterization are discussed.

1st International Conference on Opto-Electronics and Applied Optics

CERN Document Server

Bhattacharya, Indrani

2015-01-01

The Proceedings of First International Conference on Opto-Electronics and Applied Optics 2014, IEM OPTRONIX 2014 presents the research contributions presented in the conference by researchers from both India and abroad. Contributions from established scientists as well as students are included. The book is organized to enable easy access to various topics of interest.   The first part includes the Keynote addresses by Phillip Russell, Max Planck Institute of the Light Sciences, Erlangen, Germany and Lorenzo Pavesi, University of Trento, Italy.   The second part focuses on the Plenary Talks given by eminent scientists, namely, Azizur Rahman, City University London, London; Bishnu Pal, President, The Optical Society of India; Kamakhya Ghatak, National Institute of Technology, Agartala; Kehar Singh, Former Professor, India Institute of Technology Delhi; Mourad Zghal, SUPCOM, University of Carthage, Tunisia; Partha Roy Chaudhuri, IIT Kharagpur; S K. Bhadra, CSIR-Central Glass and Ceramic Research Institute, Kol...

Critical difference between optoelectronic properties of α- and β-SnWO4semiconductors: A DFT/HSE06 and experimental investigation

KAUST Repository

Harb, Moussab

2016-02-03

The optoelectronic properties of β-SnWO4 are investigated in details using experiments on thin film generated by rapid quenching and the first-principles quantum calculations based on the density functional theory (DFT, including the perturbation approach DFPT) and employing the PBE and the range-separated hybrid exchange-correlation HSE06 functionals. The obtained bandgap, optical absorption coefficient, dielectric constant, and charge-carrier effective masses for β-SnWO4 exhibit data irreconcilable with the reported values: e.g., a large and direct bandgap of 4.30eV (UV-responsive), inconsistent with the values in the literature (visible-responsive). These properties obtained for β-SnWO4 are distinctive from those for α-SnWO4: an indirect bandgap of 1.52eV with higher charge mobilities. These data of intrinsic stoichiometric materials suggest that the literature reported nonstoichiometric materials where defects significantly influence the optoelectronic properties. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A spin-optoelectronic detector for the simultaneous measurement of the degree of circular polarization and intensity of a laser beam

International Nuclear Information System (INIS)

Khamari, Shailesh K.; Porwal, S.; Oak, S. M.; Sharma, T. K.

2015-01-01

Simultaneous measurement of the degree of circular polarization and intensity of a laser beam is essential in advanced photonic applications. However, it is not feasible with conventional helicity dependent detectors where an additional detector is needed to measure the intensity. Here, we report the development of a spin-optoelectronic detector that can measure the degree of circular polarization and the intensity of a laser beam simultaneously. The principle of operation of device is based on the two independent fundamental phenomena occurring in Au/InP hybrid structures, namely, Inverse Spin Hall Effect (ISHE) and the Photo-Voltaic (PV) Effect. The magnitude of ISHE and PV signals is simultaneously measured across the two pairs of contacts that are made on the top of device. No cross talk is observed between the two detectors made on the same chip. The all-electronic compact device is fast, operates at room temperature, and opens up the possibility of many applications in an integrated optoelectronic platform

Ultralow surface recombination velocity in InP nanowires probed by terahertz spectroscopy.

Science.gov (United States)

Joyce, Hannah J; Wong-Leung, Jennifer; Yong, Chaw-Keong; Docherty, Callum J; Paiman, Suriati; Gao, Qiang; Tan, H Hoe; Jagadish, Chennupati; Lloyd-Hughes, James; Herz, Laura M; Johnston, Michael B

2012-10-10

Using transient terahertz photoconductivity measurements, we have made noncontact, room temperature measurements of the ultrafast charge carrier dynamics in InP nanowires. InP nanowires exhibited a very long photoconductivity lifetime of over 1 ns, and carrier lifetimes were remarkably insensitive to surface states despite the large nanowire surface area-to-volume ratio. An exceptionally low surface recombination velocity (170 cm/s) was recorded at room temperature. These results suggest that InP nanowires are prime candidates for optoelectronic devices, particularly photovoltaic devices, without the need for surface passivation. We found that the carrier mobility is not limited by nanowire diameter but is strongly limited by the presence of planar crystallographic defects such as stacking faults in these predominantly wurtzite nanowires. These findings show the great potential of very narrow InP nanowires for electronic devices but indicate that improvements in the crystallographic uniformity of InP nanowires will be critical for future nanowire device engineering.

Proposal for the award of a contract for the supply of analogue optoelectronic receiver modules for the CMS tracker

CERN Document Server

2001-01-01

This document concerns the award of a contract for the supply of 12-channel analogue optoelectronic receiver modules for the CMS Tracker. Following a market survey carried out among 56 firms in seventeen Member States and four firms in two non-Member States, a call for tenders (IT-2810/EP/CMS) was sent on 29 June 2001 to one firm in a Member State and one firm in a non-Member State. By the closing date, CERN had received one tender. The Finance Committee is invited to agree to the negotiation of a contract with NGK INSULATORS (JP), the only bidder, for the supply of 4500 units of 12-channel analogue optoelectronic receiver modules for a total amount of 228 485 949 Japanese yen, not subject to revision until 31 December 2003. At the rate of exchange stipulated in the tender, this amount is equivalent to approximately 3 110 500 Swiss francs. CERN's contribution to the total cost is 1 863 967 Swiss francs. The firm has indicated the following distribution by country of the contract value covered by this adjudica...

Toward high-resolution optoelectronic retinal prosthesis

Science.gov (United States)

Palanker, Daniel; Huie, Philip; Vankov, Alexander; Asher, Alon; Baccus, Steven

2005-04-01

It has been already demonstrated that electrical stimulation of retina can produce visual percepts in blind patients suffering from macular degeneration and retinitis pigmentosa. Current retinal implants provide very low resolution (just a few electrodes), while several thousand pixels are required for functional restoration of sight. We present a design of the optoelectronic retinal prosthetic system that can activate a retinal stimulating array with pixel density up to 2,500 pix/mm2 (geometrically corresponding to a visual acuity of 20/80), and allows for natural eye scanning rather than scanning with a head-mounted camera. The system operates similarly to "virtual reality" imaging devices used in military and medical applications. An image from a video camera is projected by a goggle-mounted infrared LED-LCD display onto the retina, activating an array of powered photodiodes in the retinal implant. Such a system provides a broad field of vision by allowing for natural eye scanning. The goggles are transparent to visible light, thus allowing for simultaneous utilization of remaining natural vision along with prosthetic stimulation. Optical control of the implant allows for simple adjustment of image processing algorithms and for learning. A major prerequisite for high resolution stimulation is the proximity of neural cells to the stimulation sites. This can be achieved with sub-retinal implants constructed in a manner that directs migration of retinal cells to target areas. Two basic implant geometries are described: perforated membranes and protruding electrode arrays. Possibility of the tactile neural stimulation is also examined.

Optoelectronic Picosecond Detection of Synchrotron X-rays

Energy Technology Data Exchange (ETDEWEB)

Durbin, Stephen M. [Purdue Univ., West Lafayette, IN (United States)

2017-08-04

The goal of this research program was to develop a detector that would measure x-ray time profiles with picosecond resolution. This was specifically aimed for use at x-ray synchrotrons, where x-ray pulse profiles have Gaussian time spreads of 50-100 ps (FWHM), so the successful development of such a detector with picosecond resolution would permit x-ray synchrotron studies to break through the pulse width barrier. That is, synchrotron time-resolved studies are currently limited to pump-probe studies that cannot reveal dynamics faster than ~50 ps, whereas the proposed detector would push this into the physically important 1 ps domain. The results of this research effort, described in detail below, are twofold: 1) the original plan to rely on converting electronic signals from a semiconductor sensor into an optical signal proved to be insufficient for generating signals with the necessary time resolution and sensitivity to be widely applicable; and 2) an all-optical method was discovered whereby the x-rays are directly absorbed in an optoelectronic material, lithium tantalate, which can then be probed by laser pulses with the desired picosecond sensitivity for detection of synchrotron x-rays. This research program has also produced new fundamental understanding of the interaction of x-rays and optical lasers in materials that has now created a viable path for true picosecond detection of synchrotron x-rays.

Hybrid optoelectronic device with multiple bistable outputs

Energy Technology Data Exchange (ETDEWEB)

Costazo-Caso, Pablo A; Jin Yiye; Gelh, Michael; Granieri, Sergio; Siahmakoun, Azad, E-mail: pcostanzo@ing.unlp.edu.are, E-mail: granieri@rose-hulma.edu, E-mail: siahmako@rose-hulma.edu [Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, IN 47803 (United States)

2011-01-01

Optoelectronic circuits which exhibit optical and electrical bistability with hysteresis behavior are proposed and experimentally demonstrated. The systems are based on semiconductor optical amplifiers (SOA), bipolar junction transistors (BJT), PIN photodiodes (PD) and laser diodes externally modulated with integrated electro-absorption modulators (LD-EAM). The device operates based on two independent phenomena leading to both electrical bistability and optical bistability. The electrical bistability is due to the series connection of two p-i-n structures (SOA, BJT, PD or LD) in reverse bias. The optical bistability is consequence of the quantum confined Stark effect (QCSE) in the multi-quantum well (MQW) structure in the intrinsic region of the device. This effect produces the optical modulation of the transmitted light through the SOA (or reflected from the PD). Finally, because the optical transmission of the SOA (in reverse bias) and the reflected light from the PD are so small, a LD-EAM modulated by the voltage across these devices are employed to obtain a higher output optical power. Experiments show that the maximum switching frequency is in MHz range and the rise/fall times lower than 1 us. The temporal response is mainly limited by the electrical capacitance of the devices and the parasitic inductances of the connecting wires. The effects of these components can be reduced in current integration technologies.

Transferrable monolithic III-nitride photonic circuit for multifunctional optoelectronics

Science.gov (United States)

Shi, Zheng; Gao, Xumin; Yuan, Jialei; Zhang, Shuai; Jiang, Yan; Zhang, Fenghua; Jiang, Yuan; Zhu, Hongbo; Wang, Yongjin

2017-12-01

A monolithic III-nitride photonic circuit with integrated functionalities was implemented by integrating multiple components with different functions into a single chip. In particular, the III-nitride-on-silicon platform is used as it integrates a transmitter, a waveguide, and a receiver into a suspended III-nitride membrane via a wafer-level procedure. Here, a 0.8-mm-diameter suspended device architecture is directly transferred from silicon to a foreign substrate by mechanically breaking the support beams. The transferred InGaN/GaN multiple-quantum-well diode (MQW-diode) exhibits a turn-on voltage of 2.8 V with a dominant electroluminescence peak at 453 nm. The transmitter and receiver share an identical InGaN/GaN MQW structure, and the integrated photonic circuit inherently works for on-chip power monitoring and in-plane visible light communication. The wire-bonded monolithic photonic circuit on glass experimentally demonstrates in-plane data transmission at 120 Mb/s, paving the way for diverse applications in intelligent displays, in-plane light communication, flexible optical sensors, and wearable III-nitride optoelectronics.

Mechanical response of wall-patterned GaAs surface

International Nuclear Information System (INIS)

Le Bourhis, E.; Patriarche, G.

2005-01-01

Wall-patterned GaAs surfaces have been elaborated by photolithography and dry etching. Different surfaces were produced in order to change the aspect ratio of the walls formed at the substrate surface. The mechanical behaviour of individual walls was investigated by nanoindentation and the responses were compared to that of a standard bulk reference (flat surface). Deviation from the bulk response is detected in a load range of 1-25 mN depending on the aspect ratio of the walls. A central plastic zone criterion is proposed in view of transmission electron microscopy images of indented walls and allows the prediction of the response deviation of a given wall if its width is known. The mechanical response of the different types of walls is further investigated in terms of stiffness, total penetration of indenter and apparent hardness, and is scanned in relation to the proximity of a wall side. Overall results show that contact stiffness remains almost unaffected by aspect ratio, while penetration drastically increases because of the free sides of the wall as compared to a flat surface (bulk substrate). The application of substrate patterning for optoelectronic devices is discussed in the perspective of eliminating residual dislocations appearing in mismatched structures

Semiconductor optoelectronic infrared spectroscopy

International Nuclear Information System (INIS)

Hollingworth, A.R.

2001-08-01

We use spectroscopy to study infrared optoelectronic inter and intraband semiconductor carrier dynamics. The overall aim of this thesis was to study both III-V and Pb chalcogenide material systems in order to show their future potential use in infrared emitters. The effects of bandstructure engineering have been studied in the output characteristics of mid-IR III-V laser diodes to show which processes (defects, radiative, Auger and phonon) dominate and whether non-radiative processes can be suppressed. A new three-beam pump probe experiment was used to investigate interband recombination directly in passive materials. Experiments on PbSe and theory for non-parabolic near-mirror bands and non-degenerate statistics were in good agreement. Comparisons with HgCdTe showed a reduction in the Auger coefficient of 1-2 orders of magnitude in the PbSe. Using Landau confinement to model spatial confinement in quantum dots (QDs) 'phonon bottlenecking' was studied. The results obtained from pump probe and cyclotron resonance saturation measurements showed a clear suppression in the cooling of carriers when Landau level separation was not resonant with LO phonon energy. When a bulk laser diode was placed in a magnetic field to produce a quasi quantum wire device the resulting enhanced differential gain and reduced Auger recombination lowered I th by 30%. This result showed many peaks in the light output which occurred when the LO phonon energy was a multiple of the Landau level separation. This showed for the first time evidence of the phonon bottleneck in a working laser device. A new technique called time resolved optically detected cyclotron resonance, was used as a precursor to finding the carrier dynamics within a spatially confined quantum dot. By moving to the case of a spatial QD using an optically detected intraband resonance it was possible to measure the energy separation interband levels and conduction and valence sublevels within the dot simultaneously. Furthermore

Probing Local Heterogeneity in the Optoelectronic Properties of Organic-Inorganic Perovskites Using Fluorescence Microscopy

Science.gov (United States)

De Quilettes, Dane W.

-of-magnitude reduction in trap state density. Next, we studied the effects of a series of post-deposition ligand treatments on the PL of polycrystalline methylammonium lead triiodide perovskite thin films. Using glow discharge optical emission spectroscopy (GDOES) and nuclear magnetic resonance (NMR) spectroscopy, we showed that the ligands are incorporated primarily at the film surface and are acting as electron donors. These results indicate it is possible to obtain thin film PL lifetime and PLQE values that are comparable to those from single crystals by control over surface chemistry. Finally, we further characterized these TOPO treated films to show, with respect to material bandgap, these passivated films could demonstrate quasi-Fermi level splittings comparable to the highest performing GaAs solar cells, reaching 96% of the Shockley-Queisser limit. Importantly, we reported internal photoluminescence quantum efficiency values of 92% under one sun illumination intensity, which are the highest values achieved to date. These results suggest that the material optoelectronic quality has been nearly optimized and further increases in voltage and device efficiency will be obtained by integrating these types of surface passivation schemes into charge carrier selective interfaces. (Abstract shortened by ProQuest.).

Functionalized ultra-low fouling carboxy- and hydroxy-functional surface platforms: Functionalization capacity, biorecognition capability and resistance to fouling from undiluted biological media

Czech Academy of Sciences Publication Activity Database

Vaisocherová, Hana; Ševců, Veronika; Adam, Pavel; Špačková, Barbora; Hegnerová, Kateřina; de los Santos Pereira, Andres; Rodriguez-Emmenegger, Cesar; Riedel, Tomáš; Houska, Milan; Brynda, Eduard; Homola, Jiří

2014-01-01

Roč. 51, 15 January (2014), s. 150-157 ISSN 0956-5663 R&D Projects: GA ČR GBP205/12/G118; GA MŠk EE2.3.30.0029 Institutional support: RVO:67985882 ; RVO:61389013 Keywords : Low-fouling coatings * Polymer brushes * Surface chemistry Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 6.409, year: 2014

Preliminary surface analysis of etched, bleached, and normal bovine enamel

International Nuclear Information System (INIS)

Ruse, N.D.; Smith, D.C.; Torneck, C.D.; Titley, K.C.

1990-01-01

X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H2O2 for 60 min; (2) immersion in 37% H3PO4 for 60 s; (3) immersion in 35% H2O2 for 60 min, in distilled water for two min, and in 37% H3PO4 for 60 s; (4) immersion in 37% H3PO4 for 60 s, in distilled water for two min, and in 35% H2O2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H2O2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H3PO4, however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens. These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H2O2-treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness

Controlling microstructure of pentacene derivatives by solution processing: impact of structural anisotropy on optoelectronic properties.

Science.gov (United States)

James, David T; Frost, Jarvist M; Wade, Jessica; Nelson, Jenny; Kim, Ji-Seon

2013-09-24

The consideration of anisotropic structural properties and their impact on optoelectronic properties in small-molecule thin films is vital to understand the performance of devices incorporating crystalline organic semiconductors. Here we report on the important relationship between structural and optoelectronic anisotropy in aligned, functionalized-pentacene thin films fabricated using the solution-based zone-casting technique. The microstructure of thin films composed of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) and 6,13-bis(triethylsilylethynyl)pentacene (TES-pentacene) is systematically controlled by varying the casting speed. By controlling the structural alignment, we were able to experimentally decouple, for the first time in these films, an intramolecular absorption transition dipole (at ∼440 nm) oriented close to the pentacene short axis and an intermolecular absorption transition dipole (at ∼695 nm) oriented predominantly along the conjugated pentacene-pentacene core stacking axis (crystallographic a-axis) in both films. Using the intermolecular absorption as a signature for intermolecular delocalization, much higher optical dichroism was obtained in TES-pentacene (16 ± 6) than TIPS-pentacene (3.2 ± 0.1), which was attributed to the 1D packing structure of TES-pentacene compared to the 2D packing structure of TIPS-pentacene. This result was also supported by field-effect mobility anisotropy measurements of the films, with TES-pentacene exhibiting a higher anisotropy (∼21-47, depending on the casting speed) than TIPS-pentacene (∼3-10).

Bianchi surfaces: integrability in an arbitrary parametrization

International Nuclear Information System (INIS)

Nieszporski, Maciej; Sym, Antoni

2009-01-01

We discuss integrability of normal field equations of arbitrarily parametrized Bianchi surfaces. A geometric definition of the Bianchi surfaces is presented as well as the Baecklund transformation for the normal field equations in an arbitrarily chosen surface parametrization.

In Situ Raman Spectroscopy of COOH-Functionalized SWCNTs Trapped with Optoelectronic Tweezers

Directory of Open Access Journals (Sweden)

Peter J. Pauzauskie

2012-01-01

Full Text Available Optoelectronic tweezers (OETs were used to trap and deposit aqueous dispersions of carboxylic-acid-functionalized single-walled carbon nanotube bundles. Dark-field video microscopy was used to visualize the dynamics of the bundles both with and without virtual electrodes, showing rapid accumulation of carbon nanotubes when optical virtual electrodes are actuated. Raman microscopy was used to probe SWCNT materials following deposition onto metallic fiducial markers as well as during trapping. The local carbon nanotube concentration was observed to increase rapidly during trapping by more than an order of magnitude in less than one second due to localized optical dielectrophoresis forces. This combination of enrichment and spectroscopy with a single laser spot suggests a broad range of applications in physical, chemical, and biological sciences.

Interactive teaching and learning with smart phone app in Optoelectronic Instruments course

Science.gov (United States)

Hu, Yao; Hao, Qun; Zhou, Ya; Huang, Yifan

2017-08-01

Optoelectronic Instruments is a comprehensive professional course for senior students majored in optical engineering and similar specialties. Due to the low lecturer/ student ratio, typically less than 1:100, most of the students gave up the chance of one-to-one communication with the lecturers even when they were confused about the principle or applications of the instruments. A smart phone App Rain Classroom associated with messaging App Wechat is introduced. It enables the lecturers to receive instant feedback from students through bullet screen, push preview and review materials and post in-class quiz. Investigation also shows that 76% of the students enjoyed the new interactive tool, acknowledging its help in understanding the topic better, improving in-class interaction, and after class communications.

Investigation on the learning interest of senior undergraduate students in optoelectronics specialty

Science.gov (United States)

Wu, Shenjiang; Wang, Na; Li, Dangjuan; Liu, Chanlao

2017-08-01

With the increasing number of the graduate students, many of them have some troubles in job finding. This situation make a huge pressure on the senior students and loss them the interesting in study. This work investigate the reasons by questionnaire survey, panel discussion, interview, etc. to achieve the factors influence their learning interesting. The main reason of students do not have the motivation on study is that they do not understand the development and competition of photoelectric specialty, lack of innovation and entrepreneurship training, hysteresis of the learning knowledge and practical application. Finally, the paper gives some suggestions through teaching reform on how to improve students' learning enthusiasm. This work will contribute to the teaching and training of senior undergraduate students of optoelectronics specialty.

The normalization of surface anisotropy effects present in SEVIRI reflectances by using the MODIS BRDF method

DEFF Research Database (Denmark)

Proud, Simon Richard; Zhang, Qingling; Schaaf, Crystal

2014-01-01

A modified version of the MODerate resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF) algorithm is presented for use in the angular normalization of surface reflectance data gathered by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI...... acquisition period than the comparable MODIS products while, at the same time, removing many of the angular perturbations present within the original MSG data. The NBAR data are validated against reflectance data from the MODIS instrument and in situ data gathered at a field location in Africa throughout 2008....... It is found that the MSG retrievals are stable and are of high-quality across much of the SEVIRI disk while maintaining a higher temporal resolution than the MODIS BRDF products. However, a number of circumstances are discovered whereby the BRDF model is unable to function correctly with the SEVIRI...

M-dwarf exoplanet surface density distribution. A log-normal fit from 0.07 to 400 AU

Science.gov (United States)

Meyer, Michael R.; Amara, Adam; Reggiani, Maddalena; Quanz, Sascha P.

2018-04-01

Aims: We fit a log-normal function to the M-dwarf orbital surface density distribution of gas giant planets, over the mass range 1-10 times that of Jupiter, from 0.07 to 400 AU. Methods: We used a Markov chain Monte Carlo approach to explore the likelihoods of various parameter values consistent with point estimates of the data given our assumed functional form. Results: This fit is consistent with radial velocity, microlensing, and direct-imaging observations, is well-motivated from theoretical and phenomenological points of view, and predicts results of future surveys. We present probability distributions for each parameter and a maximum likelihood estimate solution. Conclusions: We suggest that this function makes more physical sense than other widely used functions, and we explore the implications of our results on the design of future exoplanet surveys.

The effects of shear and normal stress paths on rock friction

International Nuclear Information System (INIS)

Olsson, W.A.

1990-01-01

The effect of variable normal stress on the coefficient of friction of smooth artificial surfaces in welded tuff was studied. The shear stress response to changes in normal stress during constant-velocity sliding suggests that friction depends on the history of the normal stress; or, more generally, the path in shear/normal stress space. 6 refs., 5 figs

The influence of target erosion grade in the optoelectronic properties of AZO coatings growth by magnetron sputtering

Science.gov (United States)

Zubizarreta, C.; G-Berasategui, E.; Ciarsolo, I.; Barriga, J.; Gaspar, D.; Martins, R.; Fortunato, E.

2016-09-01

Aluminum-doped zinc oxide (AZO) transparent conductor coating has emerged as promising substitute to tin-doped indium oxide (ITO) as electrode in optoelectronic applications such as photovoltaics or light emitting diodes (LEDs). Besides its high transmission in the visible spectral region and low resistivity, AZO presents a main advantage over other candidates such as graphene, carbon nanotubes or silver nanowires; it can be deposited using the technology industrially implemented to manufacture ITO layers, the magnetron sputtering (MS). This is a productive, reliable and green manufacturing technique. But to guarantee the robustness, reproducibility and reliability of the process there are still some issues to be addressed, such as the effect and control of the target state. In this paper a thorough study of the influence of the target erosion grade in developed coatings has been performed. AZO films have been deposited from a ceramic target by RF MS. Structure, optical transmittance and electrical properties of the produced coatings have been analyzed as function of the target erosion grade. No noticeable differences have been found neither in optoelectronic properties nor in the structure of the coatings, indicating that the RF MS is a stable and consistent process through the whole life of the target.

Electronic and optoelectronic device applications based on ReS2

Science.gov (United States)

Liu, Erfu; Long, Mingsheng; Wang, Yaojia; Pan, Yiming; Ho, Chinghwa; Wang, Baigeng; Miao, Feng

Rhenium disulfide (ReS2) is a unique semiconducting TMD with distorted 1T structure and weak interlayer coupling. We have previously investigated its in-plane anisotropic property and electronic applications on FET and digital inverters. In this talk, we will present high responsivity phototransistors based on few-layer ReS2. Depending on the back gate voltage, source drain bias and incident optical light intensity, the maximum attainable photoresponsivity can reach as high as 88,600 A W-1, which is one of the highest value among individual two-dimensional materials with similar device structures. Such high photoresponsivity is attributed to the increased light absorption as well as the gain enhancement due to the existence of trap states in the few-layer ReS2 flakes. The existence of trap states is proved by temperature dependent transport measurements. It further enables the detection of weak signals. Our studies underscore ReS2 as a promising material for future electronic and sensitive optoelectronic applications.

3rd International Conference on Opto-Electronics and Applied Optics

CERN Document Server

Chakrabarti, Satyajit; Reehal, Haricharan; Lakshminarayanan, Vasudevan

2017-01-01

The Proceedings of 3rd International Conference on Opto-Electronics and Applied Optics, OPTRONIX 2016 is an effort to promote and present the research works by scientists and researchers including students in India and abroad in the area of Green Photonics and other related areas as well as to raise awareness about the recent trends of research and development in the area of the related fields. The book has been organized in such a way that it will be easier for the readers to go through and find out the topic of their interests. The first part includes the Keynote addresses by Rajesh Gupta, Department of Energy Science and Engineering, Indian Institute of Technology, Bombay; P.T. Ajith Kumar, President and Leading Scientist Light Logics Holography and Optics, Crescent Hill, Trivandrum, Kerala; and K.K. Ghosh, Institute of Engineering & Management, Kolkata, India.  The second part focuses on the Plenary and Invited Talks given by eminent scientists namely, Vasudevan Lakshminarayanan, University of Wate...

Cell surface glycopeptides from human intestinal epithelial cell lines derived from normal colon and colon adenocarcinomas

International Nuclear Information System (INIS)

Youakim, A.; Herscovics, A.

1985-01-01

The cell surface glycopeptides from an epithelial cell line (CCL 239) derived from normal human colon were compared with those from three cell lines (HCT-8R, HCT-15, and CaCo-2) derived independently from human colonic adenocarcinomas. Cells were incubated with D-[2- 3 H]mannose or L-[5,6- 3 H]fucose for 24 h and treated with trypsin to release cell surface components which were then digested exhaustively with Pronase and fractionated on Bio-Gel P-6 before and after treatment with endo-beta-N-acetylglucosaminidase H. The most noticeable difference between the labeled glycopeptides from the tumor and CCL 239 cells was the presence in the former of an endo-beta-N-acetylglucosaminidase H-resistant high molecular weight glycopeptide fraction which was eluted in the void volume of Bio-Gel P-6. This fraction was obtained with both labeled mannose and fucose as precursors. However, acid hydrolysis of this fraction obtained after incubation with [2- 3 H]mannose revealed that as much as 60-90% of the radioactivity was recovered as fucose. Analysis of the total glycopeptides (cell surface and cell pellet) obtained after incubation with [2- 3 H]mannose showed that from 40-45% of the radioactivity in the tumor cells and less than 10% of the radioactivity in the CCL 239 cells was recovered as fucose. After incubation of the HCT-8R cells with D-[1,6- 3 H]glucosamine and L-[1- 14 C]fucose, strong acid hydrolysis of the labeled glycopeptide fraction excluded from Bio-Gel P-6 produced 3 H-labeled N-acetylglucosamine and N-acetylgalactosamine

Effect of Ge atoms on crystal structure and optoelectronic properties of hydrogenated Si-Ge films

Science.gov (United States)

Li, Tianwei; Zhang, Jianjun; Ma, Ying; Yu, Yunwu; Zhao, Ying

2017-07-01

Optoelectronic and structural properties of hydrogenated microcrystalline silicon-germanium (μc-Si1-xGex:H) alloys prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) were investigated. When the Ge atoms were predominantly incorporated in amorphous matrix, the dark and photo-conductivity decreased due to the reduced crystalline volume fraction of the Si atoms (XSi-Si) and the increased Ge dangling bond density. The photosensitivity decreased monotonously with Ge incorporation under higher hydrogen dilution condition, which was attributed to the increase in both crystallization of Ge and the defect density.

On rationally supported surfaces

DEFF Research Database (Denmark)

Gravesen, Jens; Juttler, B.; Sir, Z.

2008-01-01

We analyze the class of surfaces which are equipped with rational support functions. Any rational support function can be decomposed into a symmetric (even) and an antisymmetric (odd) part. We analyze certain geometric properties of surfaces with odd and even rational support functions....... In particular it is shown that odd rational support functions correspond to those rational surfaces which can be equipped with a linear field of normal vectors, which were discussed by Sampoli et al. (Sampoli, M.L., Peternell, M., Juttler, B., 2006. Rational surfaces with linear normals and their convolutions...... with rational surfaces. Comput. Aided Geom. Design 23, 179-192). As shown recently, this class of surfaces includes non-developable quadratic triangular Bezier surface patches (Lavicka, M., Bastl, B., 2007. Rational hypersurfaces with rational convolutions. Comput. Aided Geom. Design 24, 410426; Peternell, M...

Extreme conditions synthesis, processing and characterization of metal-nitrides and alloys of mechanical and optoelectronic importance

International Nuclear Information System (INIS)

Serghiou, G; McGaff, A J; Russell, N; Morniroli, J P; Frost, D J; Odling, N; Boehler, R; Troadec, D; Lathe, C

2010-01-01

High density nitrides and group IV alloys are of growing importance for both ceramic and optoelectronic applications. We present here new data and processes in our ongoing preparation of alkaline earth and transition metal nitrides as well as group IV alloys, here, up to 25 GPa and 2300 K. We employ large volume and laser-heated diamond anvil cell techniques for synthesis, processing tools including focused ion beam, and synchrotron X-ray diffraction, transmission electron microscopy and scanning electron microscopy for characterization.

Precaval retropancreatic space: Normal anatomy

Energy Technology Data Exchange (ETDEWEB)

Lee, Yeon Hee; Kim, Ki Whang; Kim, Myung Jin; Yoo, Hyung Sik; Lee, Jong Tae [Yonsei University College of Medicine, Seoul (Korea, Republic of)

1992-07-15

The authors defined precaval retropancreatic space as the space between pancreatic head with portal vein and IVC and analyzed the CT findings of this space to know the normal structures and size in this space. We evaluated 100 cases of normal abdominal CT scan to find out normal anatomic structures of precaval retropancreatic space retrospectively. We also measured the distance between these structures and calculated the minimum, maximum and mean values. At the splenoportal confluence level, normal structures between portal vein and IVC were vessel (21%), lymph node (19%), and caudate lobe of liver (2%) in order of frequency. The maximum AP diameter of portocaval lymph node was 4 mm. Common bile duct (CBD) was seen in 44% and the diameter was mean 3 mm and maximum 11 mm. CBD was located in extrapancreatic (75%) and lateral (60.6%) to pancreatic head. At IVC-left renal vein level, the maximum distance between CBD and IVC was 5 mm and the structure between posterior pancreatic surface and IVC was only fat tissue. Knowledge of these normal structures and measurement will be helpful in differentiating pancreatic mass with retropancreatic mass such as lymphadenopathy.

Tuning the work function of VO_2(1 0 0) surface by Ag adsorption and incorporation: Insights from first-principles calculations

International Nuclear Information System (INIS)

Chen, Lanli; Wang, Xiaofang; Shi, Siqi; Cui, Yuanyuan; Luo, Hongjie; Gao, Yanfeng

2016-01-01

Graphical abstract: - Highlights: • After adsorption, there is a charge transfer from Ag to VO_2(1 0 0) surface, which thus increases the electron concentration in VO_2 thin film. • Ag adsorption on VO_2(1 0 0) surface process is an exothermic chemical process, and the adsorption system is stable. • The work function can be tuned by Ag adsorption on and incorporation into the VO_2(1 0 0) surface, which in turn regulates the phase transition temperature of VO_2. - Abstract: VO_2 is an attractive material for application to thermochromic optoelectronic devices such as smart windows, and Ag/VO_2 double-layered structure can effectively decrease the phase transition temperature (T_c) of VO_2 thin film, which is very important for practical application of VO_2. Previous works has shown that the decrease in phase transition temperature (T_c) seems to be relevant with the work function of VO_2 in Ag/VO_2 double-layered thin film, although the underlying mechanism of tuning its T_c by Ag incorporation and adsorption on the VO_2(1 0 0) surface has been rarely investigated. Our first-principles calculations reveal that the adsorption of Ag atoms on the VO_2(1 0 0) surface rather than incorporation of Ag exhibits a lower work function, which is ascribed to an integrated effect of charge transfer from Ag to VO_2(1 0 0) surface and enhanced surface dipole moment. The results suggest that the decrease in work function of VO_2 with Ag adsorption favors the reduction in T_c. The current findings are helpful to understand the fundamental mechanism for yielding high-efficiency VO_2-based optoelectronic devices.

6th conference on Advances in Optoelectronics and Micro/nano-optics

International Nuclear Information System (INIS)

2017-01-01

The 6th Conference on Advances in Optoelectronics and Micro/nano-optics (AOM 2017) Nanjing, China April 23 - 26, 2017 Conference Co-Chairs: Yiping Cui - Southeast University, China Xiaocong Yuan - Shenzhen University, China Shining Zhu - Nanjing University, China WELCOME Journal of physics: Conference Series is publishing a volume of conference proceedings that contains a selection of papers presented at the 6 th Conference on Advances in Optoelectronics and Micro/nano-optics (AOM 2017), which is an OSA topical meeting that started in 2009. AOM 2017, organized by The Optical Society of America, Southeast University, and Jiangsu Optical Society, was successfully held at Nanjing, China from April 23 th -26 th , 2017. It aims to bring together leading academic scientists, researchers and scholars to exchange and share their experience and research results on all aspects of optoelectronics and micro/nano-optics, and to discuss the practical challenges encountered and the solutions adopted. Located in Yangtze River Delta area and the center of east China, Nanjing is the capital of Jiangsu province and the second largest city in the east China region, turned out to be an ideal meeting place for domestic and overseas participants of this international conference. The conference program included plenary talks, invited talks, oral and poster contributions. From numerous submissions, 64 of the most promising and IOP-relevant contributions were included in this volume. The submissions present original ideas or results of general significance, supported by clear reasoning, compelling evidence relevant to the research. The authors state clearly the problems and the significance of their research to theory and practice. Being a successful conference, this event gathered more than 300 qualified and high-level researchers and experts, which created a good platform for worldwide researchers and engineers to enjoy the academic communication. Taking advantage of this opportunity, we