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A 2015 perspective on the nature of the steady-state and transient electron transport within the wurtzite phases of gallium nitride, aluminum nitride, indium nitride, and zinc oxide: a critical and retrospective review

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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS 2015年第7期26卷 4475-4512页

作者： Siddiqua, Poppy Hadi, Walid A. Shur, Michael S. O'Leary, Stephen K. Univ British Columbia Sch Engn Kelowna BC V1V 1V7 Canada Rensselaer Polytech Inst Dept Elect Comp & Syst Engn Troy NY 12180 USA

Wide energy gap semiconductors are broadly recognized as promising materials for novel electronic and optoelectronic device applications. As informed device design requires a firm grasp of the material properties of the underlying electronic materials, the electron transport that occurs within the wide energy gap semiconductors has been the focus of considerable study over the years. In an effort to provide some perspective on this rapidly evolving and burgeoning field of research, we review analyzes of the electron transport within some wide energy gap semiconductors of current interest in this paper. In order to narrow the scope of this review, we will primarily focus on the electron transport that occurs within the wurtzite phases of gallium nitride, aluminum nitride, indium nitride, and zinc oxide in this review, these materials being of great current interest to the wide energy gap semiconductor community;indium nitride, while not a wide energy gap semiconductor in of itself, is included as it is often alloyed with other wide energy gap semiconductors, the resultant alloys being wide energy gap semiconductors themselves. The electron transport that occurs within zinc-blende gallium arsenide is also considered, albeit primarily for bench-marking purposes. Most of our discussion will focus on results obtained from our ensemble semi-classical three-valley Monte Carlo simulations of the electron transport within these materials, our results conforming with state-of-the-art wide energy gap semiconductor orthodoxy. A brief tutorial on the Monte Carlo electron transport simulation approach, this approach being used to generate the results presented herein, is also provided. Steady-state and transient electron transport results are presented. The evolution of the field, and a survey of the current literature, are also featured. We conclude our review by presenting some recent developments on the electron transport within these materials.

关键词： Energy gap

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Mechanical and quasi-optical design of ECH/ECCD launcher for JT-60SA

Mechanical and quasi-optical design of ECH/ECCD launcher for...

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28th Symposium on Fusion Technology (SOFT)

作者： Kobayashi, Takayuki Moriyama, Shinichi Isayama, Akihiko Hiranai, Shinichi Yokokura, Kenji Sawahata, Masayuki Terakado, Masayuki Wada, Kenji Sato, Yoshikatsu Hinata, Jun Hoshino, Katsumichi Takahashi, Koji Kajiwara, Ken Oda, Yasuhisa Ikeda, Ryosuke Sakamoto, Keishi Japan Atom Energy Agcy Naka Ibaraki 3110193 Japan

Mechanical and quasi-optical design of an electron cyclotron heating/current drive launcher for JT-60SA is in progress. A full-scale mock-up of the steering structure, which enables linear and rotation motions of the first mirror of the launcher, has been fabricated for cyclic test of the bellows part. Moreover, an improved design enables easy replacement of the bellows for rotation for maintenance. Quasi-optical characteristics of the antenna mirrors have been studied to evaluate its transmission efficiency and beam focusing property. In calculation, it was found that the antenna is applicable to two frequency operation at 110 GHz and 138 GHz. It was quantitatively shown that the transmission efficiency of similar to 99% (not including Ohmic loss) is obtained even with the higher order mode (LP11even) fraction of 10% by optimizations of the shape of the first mirror. These results contribute to optimization/finalization of the launcher design toward fabrication of the launcher for JT-60SA. (C) 2015 Elsevier B.v. All rights reserved.

关键词： ECH ECCD Launcher Mock-up Higher order mode

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Progress towards a multi-modal capsule endoscopy device featuring microultrasound imaging

Progress towards a multi-modal capsule endoscopy device feat...

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IEEE International Ultrasonics Symposium

作者： H S Lay Y Qiu M Al-Rawhani J Beeley R Poltarjonoks v Seetohul D Cumming S Cochran G Cummins M P Y Desmulliez M Wallace S. Trolier-McKinstry R McPhillips B F Cox C E M Demore School of Engineering University of Glasgow UK School of Engineering and Physical Sciences Heriot-Watt University Edinburgh UK Materials Research Institute The Pennsylvania State University University Park USA School of Medicine University of Dundee UK Physical Sciences Platform Sunnybrook Research Institute Medical Biophysics University of Toronto Canada

ISBN: (纸本)9781467398985

current clinical standards for endoscopy in the gastrointestinal (GI) tract combine high definition optics and ultrasound imaging to view the lumen superficially and through its thickness. However, these instruments are limited to the length of an endoscope and the only clinically available, autonomous devices able to travel the full length of the GI tract easily offer only video capsule endoscopy (vCE). Our work seeks to overcome this limitation with a device ("Sonopill") for multimodal capsule endoscopy, providing optical and microultrasound (μUS) imaging and supporting sensors. μUS transducers have been developed with multiple piezoelectric materials operating across a range of centre frequencies to study viability in the GI tract. Because of the combined constraints of μUS imaging and the low power/heat tolerance of autonomous devices, a hybrid approach has been taken to the transducer design, with separate transmit and receive arrays allowing multiple manufacturing approaches to maximise system efficiency. To explore these approaches fully, prototype devices have been developed with PvDF, high-frequency PZT and PMN-PT composites, and piezoelectric micromachined ultrasonic transducer arrays. Test capsules have been developed using 3D printing to investigate issues including power consumption, heat generation/dissipation, acoustic coupling, signal strength and capsule integrity. Because of the high functional density of the electronics in our proposed system, application specific integrated circuits (ASICs) have been developed to realise the ultrasound transmit and receive circuitry along with white-light and autofluorescence imaging with singlephoton avalanche detectors (SPADs). The ultrasound ASIC has been developed and the SPAD electronics and optical subsystem have been validated experimentally. The functionality of various transducer materials.

关键词： Transducers Ultrasonic imaging Imaging Endoscopes Acoustics Testing Prototypes Gastrointestinal Tract Endoscopes Transducers Ultrasonography Acoustics Imaging Capsule Endoscopy PROTOTYPE application specific integrated circuits Electronics Printing, Three-Dimensional

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design of organic ternary blends and small-molecule bulk heterojunctions: photophysical considerations

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JOURNAL OF PHOTONICS FOR ENERGY 2015年第1期5卷

作者： Rajesh, Kallarakkal Ramakrishnan Paudel, Keshab Johnson, Brian Hallani, Rawad Anthony, John Ostroverkhova, Oksana Oregon State Univ Dept Phys Corvallis OR 97331 USA Univ Kentucky Dept Chem Lexington KY 40506 USA

We explored relationships between photophysical processes and solar cell characteristics in solution-processable bulk heterojunctions (BHJs), in particular: (1) polymer donor: fullerene acceptor: small-molecule (SM) nonfullerene acceptor, (2) polymer donor: SM donor: SM nonfullerene acceptor, and (3) SM donor: SM nonfullerene or fullerene acceptor. Addition of a nonfullerene SM acceptor to "efficient" polymer: fullerene BHJs led to a reduction in power conversion efficiency (PCE), mostly due to decreased charge photogeneration efficiency and increased disorder. By contrast, addition of an SM donor to "inefficient" polymer: SM nonfullerene acceptor BHJs led to a factor of two to three improvement in the PCE, due to improved charge photogeneration efficiency and transport. In most blends, exciplex formation was observed and correlated with a reduced short-circuit current (J(sc)) without negatively impacting the open-circuit voltage (v-oc). A factor of similar to 5 higher PCE was observed in SM donor: fullerene acceptor BHJs as compared to SMBHJs with the same SM donor but nonfullerene acceptor, due to enhanced charge carrier photogeneration in the blend with fullerene. Our study revealed that the HOMO and LUMO energies of molecules comprising a blend are not reliable parameters for predicting v-oc of the blend, and an understanding of the photophysics is necessary for interpreting solar cell characteristics and improving the molecular design of BHJs. (C) 2015 Society of Photo-optical Instrumentation Engineers (SPIE)

关键词： organic solar cells photophysics exciplex ternary blends small-molecule bulk heterojunctions

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On the validation of solid mechanics models using optical measurements and data decomposition

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SIMULATION MODELLING PRACTICE AND THEORY 2015年 52卷 92-107页

作者： Lampeas, G. Pasialis, v. Lin, X. Patterson, E. A. Univ Patras Mech Engn & Aeronaut Dept Lab Technol & Strength Mat Rion 26500 Greece Univ Liverpool Sch Engn Liverpool L69 3GH Merseyside England

engineering simulation has a significant role in the process of design and analysis of most engineered products at all scales and is used to provide elegant, light-weight, optimized designs. A major step in achieving high confidence in computational models with good predictive capabilities is model validation. It is normal practice to validate simulation models by comparing their numerical results to experimental data. However, current validation practices tend to focus on identifying hot-spots in the data and checking that the experimental and modeling results have a satisfactory agreement in these critical zones. Often the comparison is restricted to a single or a few points where the maximum stress/strain is predicted by the model. The objective of the present paper is to demonstrate a step-bystep approach for performing model validation by combining full-field optical measurement methodologies with computational simulation techniques. Two important issues of the validation procedure are discussed, i.e. effective techniques to perform data compression using the principles of orthogonal decomposition, as well as methodologies to quantify the quality of simulations and make decisions about model validity. An I-beam with open holes under three-point bending loading is selected as an exemplar of the methodology. Orthogonal decomposition by Zernike shape descriptors is performed to compress large amounts of numerical and experimental data in selected regions of interest (ROI) by reducing its dimensionality while preserving information;and different comparison techniques including traditional error norms, a linear comparison methodology and a concordance coefficient correlation are used in order to make decisions about the validity of the simulation. (C) 2015 Elsevier B.v. All rights reserved.

关键词： Digital image correlation Full-field measurements Zernike moment descriptor Simulation validation Concordance coefficient

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Results and developments from the 12m Davies-Cotton Medium-Sized Telescope prototype for the Cherenkov Telescope Array 7

Results and developments from the 12m Davies-Cotton Medium-S...

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Conference on Optics for EUv, X-Ray, and Gamma-Ray Astronomy vII as part of the SPIE Optics + Photonics International Symposium on optical engineering + Applications

作者： Oakes, Louise Garczarczyk, Markus Schlenstedt, Stefan Sternberger, Ronny Schwanke, Ullrich Humboldt Univ Berlin Germany DESY Zeuthen Germany

ISBN: (纸本)9781628417692

The Cherenkov Telescope Array (CTA) will be the next generation ground-based observatory for gamma-ray astronomy, covering an energy range from a few tens of Gev to a few hundred Tev. The CTA project is currently in the design and prototyping phase, the start of construction is planned for 2016. The planned sensitivity of CTA improves on current ground based Cherenkov telescope experiments by about an order of magnitude. In the core energy range this sensitivity will be dominated by up to 40 Medium-Sized Telescopes (MSTs). These telescopes, of a modified Davies-Cotton mount type with a reflector diameter of 12 m, are currently being prototyped. A full-size mechanical prototype has been operating in Berlin since 2012. Several types of prototype mirrors have been developed and tested, and are mounted on the telescope. CCD cameras with various lenses are mounted on the prototype for studying deformation of the structure, testing alignment techniques, and telescope pointing using astrometry methods. The report will focus on results of optical and structural measurements, commissioning and testing of the MST prototype in Berlin, as well as the final design.

关键词： CTA Cherenkov Telescope MST Davies-Cotton

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Electrostatic phase separation: A review

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CHEMICAL engineering RESEARCH & design 2015年 96卷 177-195页

作者： Mhatre, S. vivacqua, v. Ghadiri, M. Abdullah, A. M. Al-Marri, M. J. Hassanpour, A. Hewakandamby, B. Azzopardi, B. Kermani, B. Qatar Univ Ctr Adv Mat Doha 2713 Qatar Univ Leeds Inst Particle Sci & Engn Leeds LS2 9JT W Yorkshire England Qatar Univ Gas Proc Ctr Doha 2713 Qatar Univ Nottingham Dept Chem & Environm Engn Nottingham NG7 2RD England Keytech Camberley GU15 2BN Surrey England

The current understanding and developments in the electrostatic phase separation are reviewed. The literature covers predominantly two immiscible and inter-dispersed liquids following the last review on the topic some 15 years. Electrocoalescence kinetics and governing parameters, such as the applied field, liquid properties, drop shape and flow, are considered. The unfavorable effects, such as chain formation and partial coalescence, are discussed in detail. Moreover, the prospects of microfluidics platforms, non-uniform fields, coalescence on the dielectric surfaces to enhance the electrocoalescence rate are also considered. In addition to the electrocoalescence in water-in-oil emulsions the research in oil-in-oil coalescence is also discussed. Finally the studies in electrocoalescer development and commercial devices are also surveyed. The analysis of the literature reveals that the use of pulsed DC and AC electric fields is preferred over constant DC fields for efficient coalescence;but the selection of the optimum field frequency a priori is still not possible and requires further research. Some recent studies have helped to clarify important aspects of the process such as partial coalescence and drop-drop non-coalescence. On the other hand, some key phenomena such as thin film breakup and chain formation are still unclear. Some designs of inline electrocoalescers have recently been proposed;however with limited success: the inadequate knowledge of the underlying physics still prevents this technology from leaving the realm of empiricism and fully developing in one based on rigorous scientific methodology. (C) 2015 The Authors. Published by Elsevier B.v.

关键词： Electrocoalescence Phase separation Emulsion break-up Crude oil treatment

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Toward the construction of a medium size prototype Schwarzschild-Couder telescope for CTA 7

Toward the construction of a medium size prototype Schwarzsc...

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Conference on Optics for EUv, X-Ray, and Gamma-Ray Astronomy vII as part of the SPIE Optics + Photonics International Symposium on optical engineering + Applications

作者： Rousselle, J. Byrum, K. Cameron, R. Connaughton, v. Errando, M. Griffiths, S. Guarino, v. Humensky, T. B. Jenke, P. Kaaret, P. Kieda, D. Limon, M. Mognet, I. Mukherjee, R. Nieto, D. Okumura, A. Peck, A. Petrashyk, A. Ribeiro, D. Stevenson, B. vassiliev, v. Yu, P. Univ Calif Los Angeles Los Angeles CA 90024 USA Argonne Natl Lab Argonne IL 60439 USA SLAC Natl Accelerator Lab Menlo Pk CA USA Univ Alabama Huntsville AL USA Columbia Univ Barnard Coll New York NY 10027 USA Univ Iowa Iowa City IA 52242 USA Columbia Univ New York NY 10027 USA Univ Utah Salt Lake City UT 84112 USA Nagoya Univ Nagoya Aichi 4648601 Japan

ISBN: (纸本)9781628417692

The construction of a prototype Schwarzschild-Couder telescope (pSCT) started in early June 2015 at the Fred Lawrence Whipple Observatory in Southern Arizona, as a candidate medium-sized telescope for the Cherenkov Telescope Array (CTA). Compared to current Davies-Cotton telescopes, this novel instrument with an aplanatic two-mirror optical system will offer a wider field-of-view and improved angular resolution. In addition, the reduced plate scale of the camera allows the use of highly-integrated photon detectors such as silicon photo multipliers. As part of CTA, this design has the potential to greatly improve the performance of the next generation ground-based observatory for very high-energy (E>60 Gev) gamma-ray astronomy. In this contribution we present the design and performance of both optical and alignment systems of the pSCT.

关键词： CTA TACT vHE gamma-ray Cherenkov Schwarzschild-Couder optical system Fred Lawrence Whipple Observatory telescope prototype

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InGaP-based quantum well solar cells: Growth, structural design, and photovoltaic properties

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JOURNAL OF APPLIED PHYSICS 2016年第9期119卷 095706-095706页

作者： Hashem, Islam E. Carlin, C. Zachary Hagar, Brandon G. Colter, Peter C. Bedair, S. M. N Carolina State Univ Dept Elect & Comp Engn Raleigh NC 27695 USA

Raising the efficiency ceiling of multi-junction solar cells (MJSCs) through the use of more optimal band gap configurations of next-generation MJSC is crucial for concentrator and space systems. Towards this goal, we propose two strain balanced multiple quantum well (SBMQW) structures to tune the bandgap of InGaP-based solar cells. These structures are based on InxGa1-xAs1-zPz/InyGa1-yP (x>y) and InxGa1-xP/InyGa1-yP (x>y) well/barrier combinations, lattice matched to GaAs in a p-i-n solar cell device. The bandgap of InxGa(1-x)As(1-z)P(z)/InyGa1-yP can be tuned from 1.82 to 1.65 ev by adjusting the well composition and thickness, which promotes its use as an efficient subcell for next generation five and six junction photovoltaic devices. The thicknesses of wells and barriers are adjusted using a zero net stress balance model to prevent the formation of defects. Thin layers of InGaAsP wells have been grown thermodynamically stable with compositions within the miscibility gap for the bulk alloy. The growth conditions of the two SBMQWs and the individual layers are reported. The structures are characterized and analyzed by optical microscopy, X-ray diffraction, photoluminescence, current-voltage characteristics, and spectral response (external quantum efficiency). The effect of the well number on the excitonic absorption of InGaAsP/InGaP SBMQWs is discussed and analyzed. (C) 2016 AIP Publishing LLC.

关键词： III-v semiconductors Band gap Solar cells Thin film growth Indium

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A design of digital processing circuit for the duo-lateral PSD

A design of digital processing circuit for the duo-lateral P...

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Annual Conference of the Chinese-Society-for-optical-engineering on Applied Optics and Photonics, China (AOPC)

作者： Zhou, Weixiang Liang, Yanbing Wang, Xiaoyang Chinese Acad Sci Xian Inst Opt & Precis Mech Photoelect Measurement & Control Technol Res Dept Xian 710119 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

ISBN: (纸本)9781628418996

Beam pointing stability control technology detecting the vibration of the optical platform by detectors, using the fast steering mirror compensated the vibration displacement, thereby maintaining a stable beam. Position Sensitive Detector (PSD) as a sensitive position detection system components, its performance significantly affect the overall accuracy of the test system. This article selects Sitek's two-dimensional duo-lateral PSD: 2L20_CP7. By analyzing the measurement principle of the PSD, we designed a reverse bias circuit, I-v converted circuit, A / D converted circuit and control circuit which FPGA as a controller, testing the output current value to verify the reasonableness of the circuit design, and calculate the location information according to formula. We also made a measured grid chart diagram and distortion based on the application of computer, so dose error analysis. We concluded that the linearity of this PSD is better, and it can be applied in the high-precision systems.

关键词： stable detectors duo-lateral distortion linearity

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