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Sample records for hybrid photon-counting semiconductor

  1. High-Sensitivity Semiconductor Photocathodes for Space-Born UV Photon-Counting and Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Many UV photon-counting and imaging applications, including space-borne astronomy, missile tracking and guidance, UV spectroscopy for chemical/biological...

  2. 18k Channels single photon counting readout circuit for hybrid pixel detector

    Science.gov (United States)

    Maj, P.; Grybos, P.; Szczygiel, R.; Zoladz, M.; Sakumura, T.; Tsuji, Y.

    2013-01-01

    We have performed measurements of an integrated circuit named PXD18k designed for hybrid pixel semiconductor detectors used in X-ray imaging applications. The PXD18k integrated circuit, fabricated in CMOS 180 nm technology, has dimensions of 9.64 mm×20 mm and contains approximately 26 million transistors. The core of the IC is a matrix of 96×192 pixels with 100 μm×100 μm pixel size. Each pixel works in a single photon counting mode. A single pixel contains two charge sensitive amplifiers with Krummenacher feedback scheme, two shapers, two discriminators (with independent thresholds A and B) and two 16-bit ripple counters. The data are read out via eight low voltage differential signaling (LVDS) outputs with 100 Mbps rate. The power consumption is dominated by analog blocks and it is about 23 μW/pixel. The effective peaking time at the discriminator input is 30 ns and is mainly determined by the time constants of the charge sensitive amplifier (CSA). The gain is equal to 42.5 μV/e- and the equivalent noise charge is 168 e- rms (with bump-bonded silicon pixel detector). Thanks to the use of trim DACs in each pixel, the effective threshold spread at the discriminator input is only 1.79 mV. The dead time of the front end electronics for a standard setting is 172 ns (paralyzable model). In the standard readout mode (when the data collection time is separated from the time necessary to readout data from the chip) the PXD18k IC works with two energy thresholds per pixel. The PXD18k can also be operated in the continuous readout mode (with a zero dead time) where one can select the number of bits readout from each pixel to optimize the PXD18k frame rate. For example, for reading out 16 bits/pixel the frame rate is 2.7 kHz and for 4 bits/pixel it rises to 7.1 kHz.

  3. X-ray Imaging Using a Hybrid Photon Counting GaAs Pixel Detector

    CERN Document Server

    Schwarz, C; Göppert, R; Heijne, Erik H M; Ludwig, J; Meddeler, G; Mikulec, B; Pernigotti, E; Rogalla, M; Runge, K; Smith, K M; Snoeys, W; Söldner-Rembold, S; Watt, J

    1999-01-01

    The performance of hybrid GaAs pixel detectors as X-ray imaging sensors were investigated at room temperature. These hybrids consist of 300 mu-m thick GaAs pixel detectors, flip-chip bonded to a CMOS Single Photon Counting Chip (PCC). This chip consists of a matrix of 64 x 64 identical square pixels (170 mu-m x 170 mu-m) and covers a total area of 1.2 cm**2. The electronics in each cell comprises a preamplifier, a discriminator with a 3-bit threshold adjust and a 15-bit counter. The detector is realized by an array of Schottky diodes processed on semi-insulating LEC-GaAs bulk material. An IV-charcteristic and a detector bias voltage scan showed that the detector can be operated with voltages around 200 V. Images of various objects were taken by using a standard X-ray tube for dental diagnostics. The signal to noise ratio (SNR) was also determined. The applications of these imaging systems range from medical applications like digital mammography or dental X-ray diagnostics to non destructive material testing (...

  4. Assessment of the spectral performance of hybrid photon counting x-ray detectors.

    Science.gov (United States)

    Trueb, Peter; Zambon, Pietro; Broennimann, Christian

    2017-09-01

    Hybrid Photon Counting (HPC) detectors profoundly improved x-ray diffraction experiments at third generation synchrotron facilities. Enabling the simultaneous measurement of x-ray intensities in multiple energy bins, they also have many potential applications in the field of medical imaging. A prerequisite for this is a clean spectral response. To quantify how efficiently HPC detectors are able to assign photons to the correct energy bin, a quantity called Spectral Efficiency (SE) is introduced. This figure of merit measures the number of x-rays with correctly assigned energy normalized to the number of incoming photons. A prototype HPC detector has been used to perform precision measurements of x-ray spectra at the BESSY synchrotron. The detector consists of a novel ASIC with pixels of 75 × 75 μm2 size and a 750 μm thick CdTe sensor. The experimental data are complemented by the results of a Monte-Carlo (MC) simulation, which not only includes the physical detection process but also pulse pile-up at high photon fluxes. The spectra and the measured photon flux are used to infer the Spectral Efficiency. In the energy range from 10 to 60 keV, both the Quantum Efficiency and the Spectral Efficiency were precisely measured and simulated. Good agreement between simulation and experiment has been achieved. For the small pixels of the prototype detector, a SE between 15% and 77% has been determined. The MC simulation is used to predict the SE for various pixel sizes at different photon fluxes. For a typical flux of 5∙107  photons/mm2 /s used in human Computed Tomography (CT), the highest SE is achieved for pixel sizes in the range between 150 × 150 μm2 and 300 × 300 μm2 . The Spectral Efficiency turns out to be a useful figure of merit to quantify the spectral performance of HPC detectors. It allows a quantitative comparison of detectors with different sensor and ASIC configurations over a broad range of x-ray energies and fluxes. The maximization of

  5. Multiple-Event, Single-Photon Counting Imaging Sensor

    Science.gov (United States)

    Zheng, Xinyu; Cunningham, Thomas J.; Sun, Chao; Wang, Kang L.

    2011-01-01

    The single-photon counting imaging sensor is typically an array of silicon Geiger-mode avalanche photodiodes that are monolithically integrated with CMOS (complementary metal oxide semiconductor) readout, signal processing, and addressing circuits located in each pixel and the peripheral area of the chip. The major problem is its single-event method for photon count number registration. A single-event single-photon counting imaging array only allows registration of up to one photon count in each of its pixels during a frame time, i.e., the interval between two successive pixel reset operations. Since the frame time can t be too short, this will lead to very low dynamic range and make the sensor merely useful for very low flux environments. The second problem of the prior technique is a limited fill factor resulting from consumption of chip area by the monolithically integrated CMOS readout in pixels. The resulting low photon collection efficiency will substantially ruin any benefit gained from the very sensitive single-photon counting detection. The single-photon counting imaging sensor developed in this work has a novel multiple-event architecture, which allows each of its pixels to register as more than one million (or more) photon-counting events during a frame time. Because of a consequently boosted dynamic range, the imaging array of the invention is capable of performing single-photon counting under ultra-low light through high-flux environments. On the other hand, since the multiple-event architecture is implemented in a hybrid structure, back-illumination and close-to-unity fill factor can be realized, and maximized quantum efficiency can also be achieved in the detector array.

  6. Simulation results for PLATO: a prototype hybrid X-ray photon counting detector with a low energy threshold for fusion plasma diagnostics

    Science.gov (United States)

    Habib, A.; Menouni, M.; Pangaud, P.; Fenzi, C.; Colledani, G.; Moureau, G.; Escarguel, A.; Morel, C.

    2017-01-01

    PLATO is a prototype hybrid X-ray photon counting detector that has been designed to meet the specifications for plasma diagnostics for the WEST tokamak platform (Tungsten (W) Environment in Steady-state Tokamak) in southern France, with potential perspectives for ITER. PLATO represents a customized solution that fulfills high sensitivity, low dispersion and high photon counting rate. The PLATO prototype matrix is composed of 16 × 18 pixels with a 70 μm pixel pitch. New techniques have been used in analog sensitive blocks to minimize noise coupling through supply rails and substrate, and to suppress threshold dispersion across the matrix. The PLATO ASIC is designed in CMOS 0.13 μm technology and was submitted for a fabrication run in June 2016. The chip is designed to be bump-bonded to a silicon sensor. This paper presents pixel architecture as well as simulation results while highlighting novel solutions.

  7. Prospects and fundamental limitations of room temperature, non-avalanche, semiconductor photon-counting sensors (Conference Presentation)

    Science.gov (United States)

    Ma, Jiaju; Zhang, Yang; Wang, Xiaoxin; Ying, Lei; Masoodian, Saleh; Wang, Zhiyuan; Starkey, Dakota A.; Deng, Wei; Kumar, Rahul; Wu, Yang; Ghetmiri, Seyed Amir; Yu, Zongfu; Yu, Shui-Qing; Salamo, Gregory J.; Fossum, Eric R.; Liu, Jifeng

    2017-05-01

    This research investigates the fundamental limits and trade-space of quantum semiconductor photodetectors using the Schrödinger equation and the laws of thermodynamics.We envision that, to optimize the metrics of single photon detection, it is critical to maximize the optical absorption in the minimal volume and minimize the carrier transit process simultaneously. Integration of photon management with quantum charge transport/redistribution upon optical excitation can be engineered to maximize the quantum efficiency (QE) and data rate and minimize timing jitter at the same time. Due to the ultra-low capacitance of these quantum devices, even a single photoelectron transfer can induce a notable change in the voltage, enabling non-avalanche single photon detection at room temperature as has been recently demonstrated in Si quanta image sensors (QIS). In this research, uniform III-V quantum dots (QDs) and Si QIS are used as model systems to test the theory experimentally. Based on the fundamental understanding, we also propose proof-of-concept, photon-managed quantum capacitance photodetectors. Built upon the concepts of QIS and single electron transistor (SET), this novel device structure provides a model system to synergistically test the fundamental limits and tradespace predicted by the theory for semiconductor detectors. This project is sponsored under DARPA/ARO's DETECT Program: Fundamental Limits of Quantum Semiconductor Photodetectors.

  8. Development of a Schottky CdTe Medipix3RX hybrid photon counting detector with spatial and energy resolving capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Gimenez, E.N., E-mail: Eva.Gimenez@diamond.ac.uk [Diamond Light Source, Harwell Campus, Oxforshire OX11 0DE (United Kingdom); Astromskas, V. [University of Surrey (United Kingdom); Horswell, I.; Omar, D.; Spiers, J.; Tartoni, N. [Diamond Light Source, Harwell Campus, Oxforshire OX11 0DE (United Kingdom)

    2016-07-11

    A multichip CdTe-Medipix3RX detector system was developed in order to bring the advantages of photon-counting detectors to applications in the hard X-ray range of energies. The detector head consisted of 2×2 Medipix3RX ASICs bump-bonded to a 28 mm×28 mm e{sup −} collection Schottky contact CdTe sensor. Schottky CdTe sensors undergo performance degrading polarization which increases with temperature, flux and the longer the HV is applied. Keeping the temperature stable and periodically refreshing the high voltage bias supply was used to minimize the polarization and achieve a stable and reproducible detector response. This leads to good quality images and successful results on the energy resolving capabilities of the system. - Highlights: • A high atomic number (CdTe sensor based) photon-counting detector was developed. • Polarization effects affected the image were minimized by regularly refreshing the bias voltage and stabilizing the temperature. • Good spatial resolution and image quality was achieved following this procedure.

  9. Photon-counting image sensors

    CERN Document Server

    Teranishi, Nobukazu; Theuwissen, Albert; Stoppa, David; Charbon, Edoardo

    2017-01-01

    The field of photon-counting image sensors is advancing rapidly with the development of various solid-state image sensor technologies including single photon avalanche detectors (SPADs) and deep-sub-electron read noise CMOS image sensor pixels. This foundational platform technology will enable opportunities for new imaging modalities and instrumentation for science and industry, as well as new consumer applications. Papers discussing various photon-counting image sensor technologies and selected new applications are presented in this all-invited Special Issue.

  10. Sub electron readout noise & photon counting devices

    Science.gov (United States)

    Gach, J.-L.; Balard, Ph.; Daigle, O.; Destefanis, G.; Feautrier, Ph.; Guillaume, Ch.; Rothman, J.

    We present recent advances on ultra low noise visible detectors at Laboratoire d'Astrophysique de Marseille, photon counting and EMCCD developments in collaboration with Observatoire de haute provence, Laboratoire d'astrophysique de l'observatoire de Grenoble and Laboratoire d'Astrophysique Experimentale (Montreal). After a review of the progress with third generation Image Photon Counting Systems (IPCS), we present the OCAM camera, based on the E2V CCD220 EMCCD, part of the Opticon JRA2 programme, and the CCCP controller, a new controller for the 3DNTT instrument that reduces the clock induced charge of an EMCCD by a factor 10, making it competitive with IPCS detectors for very faint fluxes. We will finally present the RAPID project and the concept of photon counting avalanche photodiode CMOS device (in collaboration with CEA-LETI) which is foreseen to be the ultimate detector for the visible-IR range providing no readout noise, high QE and extremely fast readout.

  11. Hybridization at superconductor-semiconductor interfaces

    OpenAIRE

    Mikkelsen, August E. G.; Kotetes, Panagiotis; Krogstrup, Peter; Flensberg, Karsten

    2018-01-01

    Hybrid superconductor-semiconductor devices are currently one of the most promising platforms for realizing Majorana zero modes. We address the role of band bending and superconductor-semiconductor hybridization in such devices by analyzing a gated single Al-InAs interface using a self-consistent Schroedinger-Poisson approach. Our numerical analysis shows that the band bending leads to an interface quantum well, which localizes the charge in the system near the superconductor-semiconductor in...

  12. Photon Counting Chirped Amplitude Modulation Ladar

    Science.gov (United States)

    2008-03-01

    a computer simulation of the photon counting chirped AM ladar technique in MathCAD * and presented results from the computer simulation using a two... MathCAD is a trademark of Mathsoft Inc. 4 Figure 3. Magnitude spectrum of the IF waveform from the first chirped AM

  13. Semiconductor/High-Tc-Superconductor Hybrid ICs

    Science.gov (United States)

    Burns, Michael J.

    1995-01-01

    Hybrid integrated circuits (ICs) containing both Si-based semiconducting and YBa(2)Cu(3)O(7-x) superconducting circuit elements on sapphire substrates developed. Help to prevent diffusion of Cu from superconductors into semiconductors. These hybrid ICs combine superconducting and semiconducting features unavailable in superconducting or semiconducting circuitry alone. For example, complementary metal oxide/semiconductor (CMOS) readout and memory devices integrated with fast-switching Josephson-junction super-conducting logic devices and zero-resistance interconnections.

  14. Photon Counting Using Edge-Detection Algorithm

    Science.gov (United States)

    Gin, Jonathan W.; Nguyen, Danh H.; Farr, William H.

    2010-01-01

    New applications such as high-datarate, photon-starved, free-space optical communications require photon counting at flux rates into gigaphoton-per-second regimes coupled with subnanosecond timing accuracy. Current single-photon detectors that are capable of handling such operating conditions are designed in an array format and produce output pulses that span multiple sample times. In order to discern one pulse from another and not to overcount the number of incoming photons, a detection algorithm must be applied to the sampled detector output pulses. As flux rates increase, the ability to implement such a detection algorithm becomes difficult within a digital processor that may reside within a field-programmable gate array (FPGA). Systems have been developed and implemented to both characterize gigahertz bandwidth single-photon detectors, as well as process photon count signals at rates into gigaphotons per second in order to implement communications links at SCPPM (serial concatenated pulse position modulation) encoded data rates exceeding 100 megabits per second with efficiencies greater than two bits per detected photon. A hardware edge-detection algorithm and corresponding signal combining and deserialization hardware were developed to meet these requirements at sample rates up to 10 GHz. The photon discriminator deserializer hardware board accepts four inputs, which allows for the ability to take inputs from a quadphoton counting detector, to support requirements for optical tracking with a reduced number of hardware components. The four inputs are hardware leading-edge detected independently. After leading-edge detection, the resultant samples are ORed together prior to deserialization. The deserialization is performed to reduce the rate at which data is passed to a digital signal processor, perhaps residing within an FPGA. The hardware implements four separate analog inputs that are connected through RF connectors. Each analog input is fed to a high-speed 1

  15. Spectroscopic micro-tomography of metallic-organic composites by means of photon-counting detectors

    Science.gov (United States)

    Pichotka, M.; Jakubek, J.; Vavrik, D.

    2015-12-01

    The presumed capabilities of photon counting detectors have aroused major expectations in several fields of research. In the field of nuclear imaging ample benefits over standard detectors are to be expected from photon counting devices. First of all a very high contrast, as has by now been verified in numerous experiments. The spectroscopic capabilities of photon counting detectors further allow material decomposition in computed tomography and therefore inherently adequate beam hardening correction. For these reasons measurement setups featuring standard X-ray tubes combined with photon counting detectors constitute a possible replacement of the much more cost intensive tomographic setups at synchrotron light-sources. The actual application of photon counting detectors in radiographic setups in recent years has been impeded by a number of practical issues, above all by restrictions in the detectors size. Currently two tomographic setups in Czech Republic feature photon counting large-area detectors (LAD) fabricated in Prague. The employed large area hybrid pixel-detector assemblies [1] consisting of 10×10/10×5 Timepix devices have a surface area of 143×143 mm2 / 143×71,5 mm2 respectively, suitable for micro-tomographic applications. In the near future LAD devices featuring the Medipix3 readout chip as well as heavy sensors (CdTe, GaAs) will become available. Data analysis is obtained by a number of in house software tools including iterative multi-energy volume reconstruction.In this paper tomographic analysis of of metallic-organic composites is employed to illustrate the capabilities of our technology. Other than successful material decomposition by spectroscopic tomography we present a method to suppress metal artefacts under certain conditions.

  16. Hybrid system of semiconductor and photosynthetic protein

    Science.gov (United States)

    Kim, Younghye; Shin, Seon Ae; Lee, Jaehun; Yang, Ki Dong; Nam, Ki Tae

    2014-08-01

    Photosynthetic protein has the potential to be a new attractive material for solar energy absorption and conversion. The development of semiconductor/photosynthetic protein hybrids is an example of recent progress toward efficient, clean and nanostructured photoelectric systems. In the review, two biohybrid systems interacting through different communicating methods are addressed: (1) a photosynthetic protein immobilized semiconductor electrode operating via electron transfer and (2) a hybrid of semiconductor quantum dots and photosynthetic protein operating via energy transfer. The proper selection of materials and functional and structural modification of the components and optimal conjugation between them are the main issues discussed in the review. In conclusion, we propose the direction of future biohybrid systems for solar energy conversion systems, optical biosensors and photoelectric devices.

  17. Photon counting arrays for AO wavefront sensors

    CERN Document Server

    Vallerga, J; McPhate, J; Mikulec, Bettina; Clark, Allan G; Siegmund, O; CERN. Geneva

    2005-01-01

    Future wavefront sensors for AO on large telescopes will require a large number of pixels and must operate at high frame rates. Unfortunately for CCDs, there is a readout noise penalty for operating faster, and this noise can add up rather quickly when considering the number of pixels required for the extended shape of a sodium laser guide star observed with a large telescope. Imaging photon counting detectors have zero readout noise and many pixels, but have suffered in the past with low QE at the longer wavelengths (>500 nm). Recent developments in GaAs photocathode technology, CMOS ASIC readouts and FPGA processing electronics have resulted in noiseless WFS detector designs that are competitive with silicon array detectors, though at ~40% the QE of CCDs. We review noiseless array detectors and compare their centroiding performance with CCDs using the best available characteristics of each. We show that for sub-aperture binning of 6x6 and greater that noiseless detectors have a smaller centroid error at flu...

  18. Quantum Biometrics with Retinal Photon Counting

    Science.gov (United States)

    Loulakis, M.; Blatsios, G.; Vrettou, C. S.; Kominis, I. K.

    2017-10-01

    It is known that the eye's scotopic photodetectors, rhodopsin molecules, and their associated phototransduction mechanism leading to light perception, are efficient single-photon counters. We here use the photon-counting principles of human rod vision to propose a secure quantum biometric identification based on the quantum-statistical properties of retinal photon detection. The photon path along the human eye until its detection by rod cells is modeled as a filter having a specific transmission coefficient. Precisely determining its value from the photodetection statistics registered by the conscious observer is a quantum parameter estimation problem that leads to a quantum secure identification method. The probabilities for false-positive and false-negative identification of this biometric technique can readily approach 10-10 and 10-4, respectively. The security of the biometric method can be further quantified by the physics of quantum measurements. An impostor must be able to perform quantum thermometry and quantum magnetometry with energy resolution better than 10-9ℏ , in order to foil the device by noninvasively monitoring the biometric activity of a user.

  19. Semiconductor quantum dot-inorganic nanotube hybrids.

    Science.gov (United States)

    Kreizman, Ronen; Schwartz, Osip; Deutsch, Zvicka; Itzhakov, Stella; Zak, Alla; Cohen, Sidney R; Tenne, Reshef; Oron, Dan

    2012-03-28

    A synthetic route for preparation of inorganic WS(2) nanotube (INT)-colloidal semiconductor quantum dot (QD) hybrid structures is developed, and transient carrier dynamics on these hybrids are studied via transient photoluminescence spectroscopy utilizing several different types of QDs. Measurements reveal efficient resonant energy transfer from the QDs to the INT upon photoexcitation, provided that the QD emission is at a higher energy than the INT direct gap. Charge transfer in the hybrid system, characterized using QDs with band gaps below the INT direct gap, is found to be absent. This is attributed to the presence of an organic barrier layer due to the relatively long-chain organic ligands of the QDs under study. This system, analogous to carbon nanotube-QD hybrids, holds potential for a variety of applications, including photovoltaics, luminescence tagging and optoelectronics.

  20. Cascaded systems analysis of photon counting detectors.

    Science.gov (United States)

    Xu, J; Zbijewski, W; Gang, G; Stayman, J W; Taguchi, K; Lundqvist, M; Fredenberg, E; Carrino, J A; Siewerdsen, J H

    2014-10-01

    Photon counting detectors (PCDs) are an emerging technology with applications in spectral and low-dose radiographic and tomographic imaging. This paper develops an analytical model of PCD imaging performance, including the system gain, modulation transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). A cascaded systems analysis model describing the propagation of quanta through the imaging chain was developed. The model was validated in comparison to the physical performance of a silicon-strip PCD implemented on an experimental imaging bench. The signal response, MTF, and NPS were measured and compared to theory as a function of exposure conditions (70 kVp, 1-7 mA), detector threshold, and readout mode (i.e., the option for coincidence detection). The model sheds new light on the dependence of spatial resolution, charge sharing, and additive noise effects on threshold selection and was used to investigate the factors governing PCD performance, including the fundamental advantages and limitations of PCDs in comparison to energy-integrating detectors (EIDs) in the linear regime for which pulse pileup can be ignored. The detector exhibited highly linear mean signal response across the system operating range and agreed well with theoretical prediction, as did the system MTF and NPS. The DQE analyzed as a function of kilovolt (peak), exposure, detector threshold, and readout mode revealed important considerations for system optimization. The model also demonstrated the important implications of false counts from both additive electronic noise and charge sharing and highlighted the system design and operational parameters that most affect detector performance in the presence of such factors: for example, increasing the detector threshold from 0 to 100 (arbitrary units of pulse height threshold roughly equivalent to 0.5 and 6 keV energy threshold, respectively), increased the f50 (spatial-frequency at which the MTF falls to a value of

  1. High Count Rate Single Photon Counting Detector Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An optical communications receiver requires efficient and high-rate photon-counting capability so that the information from every photon, received at the aperture,...

  2. Tutorial on X-ray photon counting detector characterization.

    Science.gov (United States)

    Ren, Liqiang; Zheng, Bin; Liu, Hong

    2017-11-16

    Recent advances in photon counting detection technology have led to significant research interest in X-ray imaging. As a tutorial level review, this paper covers a wide range of aspects related to X-ray photon counting detector characterization. The tutorial begins with a detailed description of the working principle and operating modes of a pixelated X-ray photon counting detector with basic architecture and detection mechanism. Currently available methods and techniques for charactering major aspects including energy response, noise floor, energy resolution, count rate performance (detector efficiency), and charge sharing effect of photon counting detectors are comprehensively reviewed. Other characterization aspects such as point spread function (PSF), line spread function (LSF), contrast transfer function (CTF), modulation transfer function (MTF), noise power spectrum (NPS), detective quantum efficiency (DQE), bias voltage, radiation damage, and polarization effect are also remarked. A cadmium telluride (CdTe) pixelated photon counting detector is employed for part of the characterization demonstration and the results are presented. This review can serve as a tutorial for X-ray imaging researchers and investigators to understand, operate, characterize, and optimize photon counting detectors for a variety of applications.

  3. Time correlated single-photon counting and fluorescence spectroscopy

    Science.gov (United States)

    Erdmann, Rainer; Enderlein, Jorg; Wahl, Michael

    2005-12-01

    A comprehensive reference on modern technological aspects of time-correlated single photon counting as used in academic and industrial applications. It thus covers areas that have either been neglected in the current literature, or for which an updated reference is not available. The book focuses on general fundamentals of photon statistics, light sources, and electronics for photon counting, time-correlated photon counting, data analysis, and fluorescence correlation techniques. One whole chapter is also devoted to applications of this universal technique in life sciences, with most of the attention given to fluorescence phenomena. The whole is backed by an appendix offering measurement examples and practical hints for data analysis. For physicists, spectroscopists, chemists, and biochemists.

  4. Estimation of atomic interaction parameters by photon counting

    DEFF Research Database (Denmark)

    Kiilerich, Alexander Holm; Mølmer, Klaus

    2014-01-01

    Detection of radiation signals is at the heart of precision metrology and sensing. In this article we show how the fluctuations in photon counting signals can be exploited to optimally extract information about the physical parameters that govern the dynamics of the emitter. For a simple two......-level emitter subject to photon counting, we show that the Fisher information and the Cram\\'er- Rao sensitivity bound based on the full detection record can be evaluated from the waiting time distribution in the fluorescence signal which can, in turn, be calculated for both perfect and imperfect detectors...

  5. Two-dimensional Semiconductor-Superconductor Hybrids

    DEFF Research Database (Denmark)

    Suominen, Henri Juhani

    heterostructures, observing clear evidence of supercurrent, and the first direct spectroscopy of an induced superconducting gap in a two-dimensional electron gas. Nonetheless, these experiments reveal inhomogeneous contacts and a soft-induced superconducting gap, likely due to disorder at the Sm-S interface....... To overcome these issues we integrate the superconductor directly into the semiconducting material growth stack, depositing it in-situ in a molecular beam epitaxy system under high vacuum. We present a number of experiments on these hybrid heterostructures, demonstrating near unity interface transparency...... with previous reports of Majorana modes in semiconductor nanowires. By offering a patternable two-dimensional platform, our approach opens up the door to experiments probing the predicted topological properties in this system....

  6. Binary projective measurement via linear optics and photon counting.

    Science.gov (United States)

    Takeoka, Masahiro; Sasaki, Masahide; Lütkenhaus, Norbert

    2006-07-28

    We investigate the implementation of binary projective measurements with linear optics. This problem can be viewed as a single-shot discrimination of two orthogonal pure quantum states. We show that any two orthogonal states can be perfectly discriminated using only linear optics, photon counting, coherent ancillary states, and feedforward. The statement holds in the asymptotic limit of a large number of these physical resources.

  7. High Time Resolution Photon Counting 3D Imaging Sensors

    Science.gov (United States)

    Siegmund, O.; Ertley, C.; Vallerga, J.

    2016-09-01

    Novel sealed tube microchannel plate (MCP) detectors using next generation cross strip (XS) anode readouts and high performance electronics have been developed to provide photon counting imaging sensors for Astronomy and high time resolution 3D remote sensing. 18 mm aperture sealed tubes with MCPs and high efficiency Super-GenII or GaAs photocathodes have been implemented to access the visible/NIR regimes for ground based research, astronomical and space sensing applications. The cross strip anode readouts in combination with PXS-II high speed event processing electronics can process high single photon counting event rates at >5 MHz ( 80 ns dead-time per event), and time stamp events to better than 25 ps. Furthermore, we are developing a high speed ASIC version of the electronics for low power/low mass spaceflight applications. For a GaAs tube the peak quantum efficiency has degraded from 30% (at 560 - 850 nm) to 25% over 4 years, but for Super-GenII tubes the peak quantum efficiency of 17% (peak at 550 nm) has remained unchanged for over 7 years. The Super-GenII tubes have a uniform spatial resolution of MCP gain photon counting operation also permits longer overall sensor lifetimes and high local counting rates. Using the high timing resolution, we have demonstrated 3D object imaging with laser pulse (630 nm 45 ps jitter Pilas laser) reflections in single photon counting mode with spatial and depth sensitivity of the order of a few millimeters. A 50 mm Planacon sealed tube was also constructed, using atomic layer deposited microchannel plates which potentially offer better overall sealed tube lifetime, quantum efficiency and gain stability. This tube achieves standard bialkali quantum efficiency levels, is stable, and has been coupled to the PXS-II electronics and used to detect and image fast laser pulse signals.

  8. A Flight Photon Counting Camera for the WFIRST Coronagraph

    Science.gov (United States)

    Morrissey, Patrick

    2018-01-01

    A photon counting camera based on the Teledyne-e2v CCD201-20 electron multiplying CCD (EMCCD) is being developed for the NASA WFIRST coronagraph, an exoplanet imaging technology development of the Jet Propulsion Laboratory (Pasadena, CA) that is scheduled to launch in 2026. The coronagraph is designed to directly image planets around nearby stars, and to characterize their spectra. The planets are exceedingly faint, providing signals similar to the detector dark current, and require the use of photon counting detectors. Red sensitivity (600-980nm) is preferred to capture spectral features of interest. Since radiation in space affects the ability of the EMCCD to transfer the required single electron signals, care has been taken to develop appropriate shielding that will protect the cameras during a five year mission. In this poster, consideration of the effects of space radiation on photon counting observations will be described with the mitigating features of the camera design. An overview of the current camera flight system electronics requirements and design will also be described.

  9. Avalanche photodiode photon counting receivers for space-borne lidars

    Science.gov (United States)

    Sun, Xiaoli; Davidson, Frederic M.

    1991-01-01

    Avalanche photodiodes (APD) are studied for uses as photon counting detectors in spaceborne lidars. Non-breakdown APD photon counters, in which the APD's are biased below the breakdown point, are shown to outperform: (1) conventional APD photon counters biased above the breakdown point; (2) conventional APD photon counters biased above the breakdown point; and (3) APD's in analog mode when the received optical signal is extremely weak. Non-breakdown APD photon counters were shown experimentally to achieve an effective photon counting quantum efficiency of 5.0 percent at lambda = 820 nm with a dead time of 15 ns and a dark count rate of 7000/s which agreed with the theoretically predicted values. The interarrival times of the counts followed an exponential distribution and the counting statistics appeared to follow a Poisson distribution with no after pulsing. It is predicted that the effective photon counting quantum efficiency can be improved to 18.7 percent at lambda = 820 nm and 1.46 percent at lambda = 1060 nm with a dead time of a few nanoseconds by using more advanced commercially available electronic components.

  10. Combination of current-integrating/photon-counting detector modules for spectral CT

    Science.gov (United States)

    Chu, Jiyang; Cong, Wenxiang; Li, Liang; Wang, Ge

    2013-10-01

    Inspired by compressive sensing theory and spectral detection technology, here we propose a novel design of a CT detector array that uses current-integrating/photon-counting modules in an interlacing fashion so that strengths of each detector type can be synergistically combined. For geometrical symmetry, an evenly alternating pattern is initially assumed for these detector modules to form a hybrid detector array. While grayscale detector modules acquire regular raw data in a large dynamic range cost-effectively, spectral detector modules simultaneously sense energy-discriminative data in multiple energy bins. A split Bregman iterative algorithm is developed for spectral CT reconstruction from projection data of an object collected with the hybrid detector array. With mathematical phantoms, an optimal ratio of the number of the spectral elements over the number of grayscale elements is determined based on classic image quality evaluation. This hybrid detector array is capable of delivering a performance comparable with that of a full spectral detector array.

  11. The Dosepix detector—an energy-resolving photon-counting pixel detector for spectrometric measurements

    CERN Document Server

    Zang, A; Ballabriga, R; Bisello, F; Campbell, M; Celi, J C; Fauler, A; Fiederle, M; Jensch, M; Kochanski, N; Llopart, X; Michel, N; Mollenhauer, U; Ritter, I; Tennert, F; Wölfel, S; Wong, W; Michel, T

    2015-01-01

    The Dosepix detector is a hybrid photon-counting pixel detector based on ideas of the Medipix and Timepix detector family. 1 mm thick cadmium telluride and 300 μm thick silicon were used as sensor material. The pixel matrix of the Dosepix consists of 16 x 16 square pixels with 12 rows of (200 μm)2 and 4 rows of (55 μm)2 sensitive area for the silicon sensor layer and 16 rows of pixels with 220 μm pixel pitch for CdTe. Besides digital energy integration and photon-counting mode, a novel concept of energy binning is included in the pixel electronics, allowing energy-resolved measurements in 16 energy bins within one acquisition. The possibilities of this detector concept range from applications in personal dosimetry and energy-resolved imaging to quality assurance of medical X-ray sources by analysis of the emitted photon spectrum. In this contribution the Dosepix detector, its response to X-rays as well as spectrum measurements with Si and CdTe sensor layer are presented. Furthermore, a first evaluation wa...

  12. Single-photon counting multicolor multiphoton fluorescence microscope.

    Science.gov (United States)

    Buehler, Christof; Kim, Ki H; Greuter, Urs; Schlumpf, Nick; So, Peter T C

    2005-01-01

    We present a multicolor multiphoton fluorescence microscope with single-photon counting sensitivity. The system integrates a standard multiphoton fluorescence microscope, an optical grating spectrograph operating in the UV-Vis wavelength region, and a 16-anode photomultiplier tube (PMT). The major technical innovation is in the development of a multichannel photon counting card (mC-PhCC) for direct signal collection from multi-anode PMTs. The electronic design of the mC-PhCC employs a high-throughput, fully-parallel, single-photon counting scheme along with a high-speed electrical or fiber-optical link interface to the data acquisition computer. There is no electronic crosstalk among the detection channels of the mC-PhCC. The collected signal remains linear up to an incident photon rate of 10(8) counts per second. The high-speed data interface offers ample bandwidth for real-time readout: 2 MByte lambda-stacks composed of 16 spectral channels, 256 x 256 pixel image with 12-bit dynamic range can be transferred at 30 frames per second. The modular design of the mC-PhCC can be readily extended to accommodate PMTs of more anodes. Data acquisition from a 64-anode PMT has been verified. As a demonstration of system performance, spectrally resolved images of fluorescent latex spheres and ex-vivo human skin are reported. The multicolor multiphoton microscope is suitable for highly sensitive, real-time, spectrally-resolved three-dimensional imaging in biomedical applications.

  13. High quantum efficiency S-20 photocathodes in photon counting detectors

    Science.gov (United States)

    Orlov, D. A.; DeFazio, J.; Duarte Pinto, S.; Glazenborg, R.; Kernen, E.

    2016-04-01

    Based on conventional S-20 processes, a new series of high quantum efficiency (QE) photocathodes has been developed that can be specifically tuned for use in the ultraviolet, blue or green regions of the spectrum. The QE values exceed 30% at maximum response, and the dark count rate is found to be as low as 30 Hz/cm2 at room temperature. This combination of properties along with a fast temporal response makes these photocathodes ideal for application in photon counting detectors, which is demonstrated with an MCP photomultiplier tube for single and multi-photoelectron detection.

  14. Ghosting phenomena in single photon counting imagers with Vernier anode.

    Science.gov (United States)

    Yang, Hao; Zhao, Baosheng; Qiurong, Yan; Liu, Yong'an; Hu, Huijun

    2011-02-01

    We provide the ghosting theory of two-dimensional Vernier anode based imagers. The single photon counting detection system based on Vernier anode is constructed. The ghosting, which occurs during the decoding of two-dimensional Vernier anode, and its possible solutions are described in detail. On the basis of the discussion of the decoding algorithm, the ghosting theoretical model is established. Phase conditions on which imaging ghosting can be avoided and the probability distribution function are proposed; the root causes of ghosting of two-dimensional Vernier anode are also discussed.

  15. Ultrafast Photon Counting Applied to Resonant Scanning STED Microscopy

    Science.gov (United States)

    Wu, Xundong; Toro, Ligia; Stefani, Enrico; Wu, Yong

    2014-01-01

    Summary To take full advantage of fast resonant scanning in super-resolution STimulated Emission Depletion (STED) microscopy, we have developed an ultrafast photon counting system based on a multi-giga-sample per second analog-to-digital conversion (ADC) chip that delivers an unprecedented 450 MHz pixel clock (2.2 ns pixel dwell time in each scan). The system achieves a large field of view (~50 × 50 μm) with fast scanning that reduces photobleaching, and advances the time-gated continuous wave (CW) STED technology to the usage of resonant scanning with hardware based time-gating. The assembled system provides superb signal-to-noise ratio and highly linear quantification of light that result in superior image quality. Also, the system design allows great flexibility in processing photon signals to further improve the dynamic range. In conclusion, we have constructed a frontier photon counting image acquisition system with ultrafast readout rate, excellent counting linearity, and with the capacity of realizing resonant-scanning CW-STED microscopy with on-line time-gated detection. PMID:25227160

  16. Photon counting detector for the personal radiography inspection system "SIBSCAN"

    Science.gov (United States)

    Babichev, E. A.; Baru, S. E.; Grigoriev, D. N.; Leonov, V. V.; Oleynikov, V. P.; Porosev, V. V.; Savinov, G. A.

    2017-02-01

    X-ray detectors operating in the energy integrating mode are successfully used in many different applications. Nevertheless the direct photon counting detectors, having the superior parameters in comparison with the integrating ones, are rarely used yet. One of the reasons for this is the low value of the electrical signal generated by a detected photon. Silicon photomultiplier (SiPM) based scintillation counters have a high detection efficiency, high electronic gain and compact dimensions. This makes them a very attractive candidate to replace routinely used detectors in many fields. More than 10 years ago the digital scanning radiography system based on multistrip ionization chamber (MIC) was suggested at Budker Institute of Nuclear Physics. The detector demonstrates excellent radiation resistance and parameter stability after 5 year operations and an imaging of up to 1000 persons per day. Currently, the installations operate at several Russian airports and at subway stations in some cities. At the present time we design a new detector operating in the photon counting mode, having superior parameters than the gas one, based on scintillator - SiPM assemblies. This detector has close to zero noise, higher quantum efficiency and a count rate capability of more than 5 MHz per channel (20% losses), which leads to better image quality and improved detection capability. The suggested detector technology could be expanded to medical applications.

  17. Novel Photon-Counting Detectors for Free-Space Communication

    Science.gov (United States)

    Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Lu, Wei; Merritt, Scott; Beck, Jeff

    2016-01-01

    We present performance data for novel photon counting detectors for free space optical communication. NASA GSFC is testing the performance of three novel photon counting detectors 1) a 2x8 mercury cadmium telluride avalanche array made by DRS Inc. 2) a commercial 2880 silicon avalanche photodiode array and 3) a prototype resonant cavity silicon avalanche photodiode array. We will present and compare dark count, photon detection efficiency, wavelength response and communication performance data for these detectors. We discuss system wavelength trades and architectures for optimizing overall communication link sensitivity, data rate and cost performance. The HgCdTe APD array has photon detection efficiencies of greater than 50 were routinely demonstrated across 5 arrays, with one array reaching a maximum PDE of 70. High resolution pixel-surface spot scans were performed and the junction diameters of the diodes were measured. The junction diameter was decreased from 31 m to 25 m resulting in a 2x increase in e-APD gain from 470 on the 2010 array to 1100 on the array delivered to NASA GSFC. Mean single photon SNRs of over 12 were demonstrated at excess noise factors of 1.2-1.3.The commercial silicon APD array has a fast output with rise times of 300ps and pulse widths of 600ps. Received and filtered signals from the entire array are multiplexed onto this single fast output. The prototype resonant cavity silicon APD array is being developed for use at 1 micron wavelength.

  18. A hybrid semiconductor-glass waveguide laser

    NARCIS (Netherlands)

    Fan, Youwen; Oldenbeuving, Ruud; Klein, E.J.; Lee, Christopher James; Song, H.; Khan, M.R.H.; Offerhaus, Herman L.; van der Slot, Petrus J.M.; Boller, Klaus J.; Mackenzie, J.I.; Jelinkova, H.; Taira, T.; Ahmed, M.A.

    2014-01-01

    abstract .We report on a novel type of laser in which a semiconductor optical amplifier (SOA) receives frequency-selective feedback from a glass-waveguide circuit. The laser we present here is based on InP for operation in the 1.55 μm wavelength range. The Si3N4/SiO2 glass waveguide circuit

  19. A hybrid semiconductor-glass waveguide laser

    NARCIS (Netherlands)

    Fan, Y.; Oldenbeuving, R.M.; Klein, E.J.; Lee, C.J.; Song, H.; Khan, M.R.H.; Offerhaus, H.L.; Van der Slot, P.J.M.; Boller, K.J.

    2014-01-01

    We report on a novel type of laser in which a semiconductor optical amplifier (SOA) receives frequency-selective feedback from a glass-waveguide circuit. The laser we present here is based on InP for operation in the 1.55 µm wavelength range. The Si3N4/SiO2 glass waveguide circuit comprises two

  20. Giant Geometrically Amplified Piezoresistance in Metal-Semiconductor Hybrid Resistors

    DEFF Research Database (Denmark)

    Hansen, Ole; Reck, Kasper; Thomsen, Erik Vilain

    2008-01-01

    We show that very high geometrically amplified piezoresistance can indeed be obtained in microstructured metal-semiconductor hybrid devices, even significantly higher amplification factors than the factor of approximately 8 demonstrated recently by Rowe and co-workers may be achieved. However, we...... than the sensitivity of conventional piezoresistors fabricated in the same piezoresistive material. ©2008 American Institute of Physics...

  1. High Temperature Superconductor/Semiconductor Hybrid Microwave Devices and Circuits

    Science.gov (United States)

    Romanofsky, Robert R.; Miranda, Felix A.

    1999-01-01

    Contents include following: film deposition technique; laser ablation; magnetron sputtering; sequential evaporation; microwave substrates; film characterization at microwave frequencies; complex conductivity; magnetic penetration depth; surface impedance; planar single-mode filters; small antennas; antenna arrays phase noise; tunable oscillations; hybrid superconductor/semiconductor receiver front ends; and noise modeling.

  2. High Gain Hybrid Graphene-Organic Semiconductor Phototransistors

    NARCIS (Netherlands)

    Huisman, Everardus H.; Shulga, Artem G.; Zomer, Paul J.; Tombros, Nikolaos; Bartesaghi, Davide; Bisri, Satria Zulkarnaen; Loi, Maria A.; Koster, L. Jan Anton; van Wees, Bart J.

    2015-01-01

    Hybrid phototransistors of graphene and the organic semiconductor poly(3-hexylthiophene-2,5-diyl) (P3HT) are presented. Two types of phototransistors are demonstrated with a charge carrier transit time that differs by more than 6 orders of magnitude. High transit time devices are fabricated using a

  3. Hybrid plasmonic/semiconductor nanoparticle monolayer assemblies as hyperbolic metamaterials

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Ozel, Tuncay; Mutlugun, Evren

    2014-01-01

    We show that hybrid nanostructures made of alternating colloidal semiconductor quantum dot and metal nanoparticle monolayers can function as multilayer hyperbolic meta-materials. By choosing the thickness of the spacer between the quantum dot and nanoparticle layers, one can achieve the indefinite...

  4. An Effective Multilevel Offset Correction Technique for Single Photon Counting Pixel Detectors

    Science.gov (United States)

    Kmon, P.; Maj, P.; Grybos, P.; Szczygiel, R.

    2016-04-01

    We report on a novel technique of an in-pixel multilevel offset correction to be used in hybrid pixel detector readout circuits operating in a single photon counting mode. This technique was implemented in a prototype integrated circuit consisting of 23,552 square shaped pixels of 75 μm pitch, which was designed and manufactured in CMOS 130 nm technology. Each pixel contains a charge sensitive amplifier, shaper, two discriminators, two 14-bit counters and a block for multilevel offset correction. The effective gain and offset are controlled individually in each pixel. The measurement results prove very good uniformity of the prototype integrated circuit with an offset spread of only 7e- rms and a gain spread of 2.5%.

  5. Soft tissue imaging with photon counting spectroscopic CT.

    Science.gov (United States)

    Shikhaliev, Polad M

    2015-03-21

    The purpose of this work was experimental investigation of photon counting spectroscopic CT (PCS-CT) imaging of anatomical soft tissue with clinically relevant size. The imaging experiments were performed using a spectroscopic CT system based on CdZnTe photon counting detector with two rows of pixels, 256 pixels in each row, 1  ×  1 mm(2) pixel size, and 25.6 cm detector length. The detector could split the x-ray energy spectrum to 5 regions (energy bins), and acquire 5 multi-energy (spectroscopic) CT images in a single CT scan. A sample of round shaped anatomical soft tissue of 14 cm diameter including lean and fat was used for imaging. To avoid the negative effect of anatomical noise on quantitative analysis, a spectroscopic CT phantom with tissue equivalent solid materials was used. The images were acquired at 60, 90, and 120 kVp tube voltages, and spectroscopic image series were acquired with 3 and 5 energy bins. Spectroscopic CT numbers were introduced and used to evaluate an energy selective image series. The anatomical soft tissue with 14 cm diameter was visualized with good quality and without substantial artifacts by the photon counting spectroscopic CT system. The effects of the energy bin crosstalk on spectroscopic CT numbers were quantified and analyzed. The single and double slice PCS-CT images were acquired and compared. Several new findings were observed, including the effect of soft tissue non-uniformity on image artifacts, unique status of highest energy bin, and material dependent visualization in spectroscopic image series. Fat-lean decomposition was performed using dual energy subtraction and threshold segmentation methods, and compared. Using K-edge filtered x-rays improved fat-lean decomposition as compared to conventional x-rays. Several new and important aspects of the PCS-CT were investigated. These include imaging soft tissue with clinically relevant size, single- and double-slice PCS-CT imaging, using spectroscopic CT

  6. Soft tissue imaging with photon counting spectroscopic CT

    Science.gov (United States)

    Shikhaliev, Polad M.

    2015-03-01

    The purpose of this work was experimental investigation of photon counting spectroscopic CT (PCS-CT) imaging of anatomical soft tissue with clinically relevant size. The imaging experiments were performed using a spectroscopic CT system based on CdZnTe photon counting detector with two rows of pixels, 256 pixels in each row, 1  ×  1 mm2 pixel size, and 25.6 cm detector length. The detector could split the x-ray energy spectrum to 5 regions (energy bins), and acquire 5 multi-energy (spectroscopic) CT images in a single CT scan. A sample of round shaped anatomical soft tissue of 14 cm diameter including lean and fat was used for imaging. To avoid the negative effect of anatomical noise on quantitative analysis, a spectroscopic CT phantom with tissue equivalent solid materials was used. The images were acquired at 60, 90, and 120 kVp tube voltages, and spectroscopic image series were acquired with 3 and 5 energy bins. Spectroscopic CT numbers were introduced and used to evaluate an energy selective image series. The anatomical soft tissue with 14 cm diameter was visualized with good quality and without substantial artifacts by the photon counting spectroscopic CT system. The effects of the energy bin crosstalk on spectroscopic CT numbers were quantified and analyzed. The single and double slice PCS-CT images were acquired and compared. Several new findings were observed, including the effect of soft tissue non-uniformity on image artifacts, unique status of highest energy bin, and material dependent visualization in spectroscopic image series. Fat-lean decomposition was performed using dual energy subtraction and threshold segmentation methods, and compared. Using K-edge filtered x-rays improved fat-lean decomposition as compared to conventional x-rays. Several new and important aspects of the PCS-CT were investigated. These include imaging soft tissue with clinically relevant size, single- and double-slice PCS-CT imaging, using spectroscopic CT

  7. Low photon count based digital holography for quadratic phase cryptography.

    Science.gov (United States)

    Muniraj, Inbarasan; Guo, Changliang; Malallah, Ra'ed; Ryle, James P; Healy, John J; Lee, Byung-Geun; Sheridan, John T

    2017-07-15

    Recently, the vulnerability of the linear canonical transform-based double random phase encryption system to attack has been demonstrated. To alleviate this, we present for the first time, to the best of our knowledge, a method for securing a two-dimensional scene using a quadratic phase encoding system operating in the photon-counted imaging (PCI) regime. Position-phase-shifting digital holography is applied to record the photon-limited encrypted complex samples. The reconstruction of the complex wavefront involves four sparse (undersampled) dataset intensity measurements (interferograms) at two different positions. Computer simulations validate that the photon-limited sparse-encrypted data has adequate information to authenticate the original data set. Finally, security analysis, employing iterative phase retrieval attacks, has been performed.

  8. Advanced time-correlated single photon counting techniques

    CERN Document Server

    Becker, Wolfgang

    2005-01-01

    Time-correlated single photon counting (TCSPC) is a remarkable technique for recording low-level light signals with extremely high precision and picosecond-time resolution. TCSPC has developed from an intrinsically time-consuming and one-dimensional technique into a fast, multi-dimensional technique to record light signals. So this reference and text describes how advanced TCSPC techniques work and demonstrates their application to time-resolved laser scanning microscopy, single molecule spectroscopy, photon correlation experiments, and diffuse optical tomography of biological tissue. It gives practical hints about constructing suitable optical systems, choosing and using detectors, detector safety, preamplifiers, and using the control features and optimising the operating conditions of TCSPC devices. Advanced TCSPC Techniques is an indispensable tool for everyone in research and development who is confronted with the task of recording low-intensity light signals in the picosecond and nanosecond range.

  9. Advanced time-correlated single photon counting applications

    CERN Document Server

    Becker, Wolfgang

    2015-01-01

    This book is an attempt to bridge the gap between the instrumental principles of multi-dimensional time-correlated single photon counting (TCSPC) and typical applications of the technique. Written by an originator of the technique and by sucessful users, it covers the basic principles of the technique, its interaction with optical imaging methods and its application to a wide range of experimental tasks in life sciences and clinical research. The book is recommended for all users of time-resolved detection techniques in biology, bio-chemistry, spectroscopy of live systems, live cell microscopy, clinical imaging, spectroscopy of single molecules, and other applications that require the detection of low-level light signals at single-photon sensitivity and picosecond time resolution.

  10. Maturing CCD Photon-Counting Technology for Space Flight

    Science.gov (United States)

    Mallik, Udayan; Lyon, Richard; Petrone, Peter; McElwain, Michael; Benford, Dominic; Clampin, Mark; Hicks, Brian

    2015-01-01

    This paper discusses charge blooming and starlight saturation - two potential technical problems - when using an Electron Multiplying Charge Coupled Device (EMCCD) type detector in a high-contrast instrument for imaging exoplanets. These problems especially affect an interferometric type coronagraph - coronagraphs that do not use a mask to physically block starlight in the science channel of the instrument. These problems are presented using images taken with a commercial Princeton Instrument EMCCD camera in the Goddard Space Flight Center's (GSFC), Interferometric Coronagraph facility. In addition, this paper discusses techniques to overcome such problems. This paper also discusses the development and architecture of a Field Programmable Gate Array and Digital-to-Analog Converter based shaped clock controller for a photon-counting EMCCD camera. The discussion contained here will inform high-contrast imaging groups in their work with EMCCD detectors.

  11. Gain Instabilities in Photomultipliers: How Accurate are Photon Counting Measurements?

    Science.gov (United States)

    Rosen, W. A.; Chromey, F. R.

    1984-01-01

    Experiments performed on five commercially available photomultiplier tubes indicate that gain instabilities can be an important source of error in photon counting measurements at the 1% level. It is shown that the error cannot be significantly reduced by standard differential measurement techniques. Analysis of time variations in the pulse height distribution is shown to be a sensitive diagnostic tool for the measurement of gain variations. Using this technique it is found that gain variations occur at counting rates as low as 100 Hz. It is argued that such errors will be present at some level in all tubes. Several calibrating schemes capable of reducing the error to below the 0.1% level are discussed.

  12. Organic / IV, III-V semiconductor hybrid solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ong, P.-L. [Emitech, Inc., Fall River, Massachusetts, 02720 (United States); Levitsky, I. A. [Emitech, Inc., Fall River, Massachusetts, 02720 (United States); Department of Chemistry, University of Rhode Island, Kingston, Rhode Island, 02881 (United States)

    2010-07-01

    We present a review of the emerging class of hybrid solar cells based on organic-semiconductor (Group IV, III-V), nanocomposites, which states separately from dye synthesized, polymer-metal oxides and organic-inorganic (Group II-VI) nanocomposite photovoltaics. The structure of such hybrid cell comprises of an organic active material (p-type) deposited by coating, printing or spraying technique on the surface of bulk or nanostructured semiconductor (n-type) forming a heterojunction between the two materials. Organic components include various photosensitive monomers (e.g., phtalocyanines or porphyrines), conjugated polymers, and carbon nanotubes. Mechanisms of the charge separation at the interface and their transport are discussed. Also, perspectives on the future development of such hybrid cells and comparative analysis with other classes of photovoltaics of third generation are presented. (author)

  13. Organic / IV, III-V Semiconductor Hybrid Solar Cells

    Directory of Open Access Journals (Sweden)

    Pang-Leen Ong

    2010-03-01

    Full Text Available We present a review of the emerging class of hybrid solar cells based on organic-semiconductor (Group IV, III-V, nanocomposites, which states separately from dye synthesized, polymer-metal oxides and organic-inorganic (Group II-VI nanocomposite photovoltaics. The structure of such hybrid cell comprises of an organic active material (p-type deposited by coating, printing or spraying technique on the surface of bulk or nanostructured semiconductor (n-type forming a heterojunction between the two materials. Organic components include various photosensitive monomers (e.g., phtalocyanines or porphyrines, conjugated polymers, and carbon nanotubes. Mechanisms of the charge separation at the interface and their transport are discussed. Also, perspectives on the future development of such hybrid cells and comparative analysis with other classes of photovoltaics of third generation are presented.

  14. Characteristic evaluation of a novel CdTe photon counting detector for X-ray imaging

    Science.gov (United States)

    Cho, Hyo-Min; Kim, Hee-Joung; Ryu, Hyun-Ju; Choi, Yu-Na

    2013-07-01

    The purpose of this paper is to investigate the characteristics of a novel cadmium-telluride (CdTe) photon counting detector optimized for X-ray imaging applications. CdTe was studied as a potential detector material for hard X-ray and gamma-ray detection. In this study, we used a CdTe photon counting detector manufactured by AJAT Ltd. (PID 350, Finland) for the purposes of both X-ray and gamma-ray detection. However, it is noted that X-ray detection can be limited by the characteristics of gamma-ray detectors. For the investigation of the characteristics of a detector for X-ray imaging, the detector has been studied in terms of detector calibration, count rate, and pixel sensitivity variation by using a poly-energetic X-ray. The detector calibration was evaluated to determine the effects of offset, gain, and energy. An optimal calibration increases the accuracy of the output energy spectrum. The pixel sensitivity variation was evaluated using profiles of various rows and columns from white (with X-ray) and dark (without X-ray) images. The specific trend of each image was observed around the edges of the hybrids. These pixel variations of the CdTe sensor were corrected. The image quality was improved by using the optimal correction method based on an understanding of the pixel sensitivity variation. The maximum recorded count rate of the detector was measured in all pixels. The count rate was measured by setting the energy windows from just above the noise level to the maximum energy. The average count rate was fairly linear up to 1.6 × 106 cps/8 modules and saturated at about 2.2 × 106 cps/8 modules. In this paper, we present several characteristics of the detector and demonstrate the improved spectrum and image obtained after calibration and correction. These results show that the novel CdTe photon counting detector can be used in conventional X-ray imaging, but exhibits limitations when applied to spectral X-ray imaging.

  15. Photon counting imaging with an electron-bombarded CCD: Towards wide-field time-correlated single photon counting (TCSPC)

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M.; Jiggins, Stephen; Sergent, Nicolas; Zanda, Gianmarco; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk

    2015-07-01

    Single photon detecting capabilities of an electron-bombarded CCD (EBCCD), where a photon is converted into a photoelectron that is accelerated through a high voltage before hitting the CCD chip, were characterised. The photon event pulse height distribution was found to be linearly dependent on the gain voltage. Based on these results, we propose that a gain voltage sweep during exposure in an EBCCD or EBCMOS camera would allow photon arrival time determination from the photon event pulse height with sub-frame exposure time resolution. This effectively uses an electron-bombarded sensor as a parallel-processing photoelectronic time-to-amplitude converter (TAC), or a 2-dimensional streak camera. Several applications that require timing of photon arrival, including fluorescence lifetime imaging microscopy (FLIM), may benefit from this approach. Moreover, the EBCCD was used on a fluorescence microscope to image fluorescently labelled cells in single photon counting mode.

  16. Imaging by photon counting with 256 x 256 pixel matrix

    CERN Document Server

    Tlustos, Lukas; Heijne, Erik H M; Llopart-Cudie, Xavier

    2004-01-01

    Using 0.25 mum standard CMOS we have developed 2-D semiconductor matrix detectors with sophisticated functionality integrated inside each pixel of a hybrid sensor module. One of these sensor modules is a matrix of 256 multiplied by 256 square 55mum pixels intended for X- ray imaging. This device is called 'Medipix2' and features a fast amplifier and two-level discrimination for signals between 1000 and 100000 equivalent electrons, with overall signal noise similar to 150 e- rms. Signal polarity and comparator thresholds are programmable. A maximum count rate of nearly 1 MHz per pixel can be achieved, which corresponds to an average flux of 3 multiplied by 10exp10 photons per cm2. The selected signals can be accumulated in each pixel in a 13- bit register. The serial readout takes 5-10 ms. A parallel readout of similar to 300 mus could also be used. Housekeeping functions such as local dark current compensation, test pulse generation, silencing of noisy pixels and threshold tuning in each pixel contribute to t...

  17. Hybrid High-Temperature-Superconductor–Semiconductor Tunnel Diode

    Directory of Open Access Journals (Sweden)

    Alex Hayat

    2012-12-01

    Full Text Available We report the demonstration of hybrid high-T_{c}-superconductor–semiconductor tunnel junctions, enabling new interdisciplinary directions in condensed matter research. The devices are fabricated by our newly developed mechanical-bonding technique, resulting in high-T_{c}-superconductor–semiconductor tunnel diodes. Tunneling-spectra characterization of the hybrid junctions of Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} combined with bulk GaAs, or a GaAs/AlGaAs quantum well, exhibits excess voltage and nonlinearity, similarly to spectra obtained in scanning-tunneling microscopy, and is in good agreement with theoretical predictions for a d-wave-superconductor–normal-material junction. Additional junctions are demonstrated using Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} combined with graphite or Bi_{2}Te_{3}. Our results pave the way for new methods in unconventional superconductivity studies, novel materials, and quantum technology applications.

  18. Extraordinary magnetoresistance in semiconductor/metal hybrids: A review

    KAUST Repository

    Sun, J.

    2013-02-13

    The Extraordinary Magnetoresistance (EMR) effect is a change in the resistance of a device upon the application of a magnetic field in hybrid structures, consisting of a semiconductor and a metal. The underlying principle of this phenomenon is a change of the current path in the hybrid structure upon application of a magnetic field, due to the Lorentz force. Specifically, the ratio of current, flowing through the highly conducting metal and the poorly conducting semiconductor, changes. The main factors for the device\\'s performance are: the device geometry, the conductivity of the metal and semiconductor, and the mobility of carriers in the semiconductor. Since the discovery of the EMR effect, much effort has been devoted to utilize its promising potential. In this review, a comprehensive overview of the research on the EMR effect and EMR devices is provided. Different geometries of EMR devices are compared with respect to MR ratio and output sensitivity, and the criteria of material selection for high-performance devices are discussed. 2013 by the authors.

  19. Photon counting spectroscopic CT with dynamic beam attenuator

    CERN Document Server

    Atak, Haluk

    2016-01-01

    Purpose: Photon counting (PC) computed tomography (CT) can provide material selective CT imaging at lowest patient dose but it suffers from suboptimal count rate. A dynamic beam attenuator (DBA) can help with count rate by modulating x-ray beam intensity such that the low attenuating areas of the patient receive lower exposure, and detector behind these areas is not overexposed. However, DBA may harden the beam and cause artifacts and errors. This work investigates positive and negative effects of using DBA in PCCT. Methods: A simple PCCT with single energy bin, spectroscopic PCCT with 2 and 5 energy bins, and conventional energy integrating CT with and without DBA were simulated and investigated using 120kVp tube voltage and 14mGy air dose. The DBAs were modeled as made from soft tissue (ST) equivalent material, iron (Fe), and holmium (Ho) K-edge material. A cylindrical CT phantom and chest phantom with iodine and CaCO3 contrast elements were used. Image artifacts and quantification errors in general and mat...

  20. Quantitative material characterization from multi-energy photon counting CT.

    Science.gov (United States)

    Alessio, Adam M; MacDonald, Lawrence R

    2013-03-01

    To quantify the concentration of soft-tissue components of water, fat, and calcium through the decomposition of the x-ray spectral signatures in multi-energy CT images. Decomposition of dual-energy and multi-energy x-ray data into basis materials can be performed in the projection domain, image domain, or during image reconstruction. In this work, the authors present methodology for the decomposition of multi-energy x-ray data in the image domain for the application of soft-tissue characterization. To demonstrate proof-of-principle, the authors apply several previously proposed methods and a novel content-aware method to multi-energy images acquired with a prototype photon counting CT system. Data from phantom and ex vivo specimens are evaluated. The number and type of materials in a region can be limited based on a priori knowledge or classification strategies. The proposed difference classifier successfully classified the image into air only, water+fat, water+fat+iodine, and water+calcium regions. Then, the content-aware material decomposition based on weighted least-square optimization generated quantitative maps of concentration. Bias in the estimation of the concentration of water and oil components in a phantom study was Decomposition of ex vivo carotid endarterectomy specimens suggests the presence of water, lipid, and calcium deposits in the plaque walls. Initial application of the proposed methodology suggests that it can decompose multi-energy CT images into quantitative maps of water, adipose, iodine, and calcium concentrations.

  1. XPAD: A photons counting pixel detector for material sciences and small-animal imaging

    Science.gov (United States)

    Delpierre, P.; Basolo, S.; Berar, J.-F.; Bordesoule, M.; Boudet, N.; Breugnon, P.; Caillot, B.; Chantepie, B.; Clemens, J. C.; Dinkespiler, B.; Hustache-Ottini, S.; Meessen, C.; Menouni, M.; Morel, C.; Mouget, C.; Pangaud, P.; Potheau, R.; Vigeolas, E.

    2007-03-01

    Experiments on high-flux and high-brilliance third-generation synchrotron X-ray sources are now limited by detector performance. Photon-counting hybrid pixel detectors are being investigated as a solution to improve the dynamic range and the readout speed of the available 2D detectors. The XPAD2 is a large-surface hybrid pixel detector (68×65 mm 2) with a dynamic response, which ranges from 0.01 to 10 6 photons/pixel/s. High-resolution data were recorded using the XPAD2. The comparison with data measured using a conventional setup shows a gain on measurement duration by a factor 20 and on dynamic range. A new generation of pixel detector (XPAD3) is presently under development. For this, a new electronic chip (the XPAD3) is designed to improve spatial resolution by using 130 μm pixels and detector efficiency by using CdTe sensors. XPAD2 is also operated with PIXSCAN, a CT scanner for mice.

  2. Breast-density measurement using photon-counting spectral mammography.

    Science.gov (United States)

    Johansson, Henrik; von Tiedemann, Miriam; Erhard, Klaus; Heese, Harald; Ding, Huanjun; Molloi, Sabee; Fredenberg, Erik

    2017-07-01

    To evaluate a method for measuring breast density using photon-counting spectral mammography. Breast density is an indicator of breast cancer risk and diagnostic accuracy in mammography, and can be used as input to personalized screening, treatment monitoring and dose estimation. The measurement method employs the spectral difference in x-ray attenuation between adipose and fibro-glandular tissue, and does not rely on any a priori information. The method was evaluated using phantom measurements on tissue-equivalent material (slabs and breast-shaped phantoms) and using clinical data from a screening population (n=1329). A state-of-the-art nonspectral method for breast-density assessment was used for benchmarking. The precision of the spectral method was estimated to be 1.5-1.8 percentage points (pp) breast density. Expected correlations were observed in the screening population for thickness versus breast density, dense volume, breast volume, and compression height. Densities ranged between 4.5% and 99.6%, and exhibited a skewed distribution with a mode of 12.5%, a median of 18.3%, and a mean of 23.7%. The precision of the nonspectral method was estimated to be 2.7-2.8 pp. The major uncertainty of the nonspectral method originated from the thickness estimate, and in particular thin/dense breasts posed problems compared to the spectral method. The spectral method yielded reasonable results in a screening population with a precision approximately two times that of the nonspectral method, which may improve or enable applications of breast-density measurement on an individual basis such as treatment monitoring and personalized screening. © 2017 American Association of Physicists in Medicine.

  3. A new cross-detection method for improved energy-resolving photon counting under pulse pile-up

    Science.gov (United States)

    Lee, Daehee; Lim, Kyung Taek; Park, Kyungjin; Lee, Changyeop; Cho, Gyuseong

    2017-09-01

    In recent, photon counting detectors (PCDs) have been replacing the energy-integrating detectors in many medical imaging applications due to the formers' high resolution, low noise, and high efficiency. Under a high flux X-ray exposure, however, a superimposition of pulses, i.e., pulse pile-up, frequently occurs due to the finite output pulse width, causing distortions in the energy spectrum as a consequence. Therefore, pulse pile-up is considered as a major constraint in using PCDs for high flux X-ray applications. In this study, a new photon counting method is proposed to minimize degradations in PCD performance due to pulse pile-up. The proposed circuit was incorporated into a pixel with a size of 200 × 200 μm2. It was fabricated by using a 1-poly 6-metal 0 . 18 μm complementary metal-oxide-semiconductor (CMOS) process and had a power consumption of 7 . 8 μW / pixel. From the result, it was shown that the maximum count rate of the proposed circuit was increased by a factor of 4.7 when compared to that of the conventional circuit at the same pulse width of 700 ns. This implies that the energy spectrum obtained by the proposed circuit is 4.7 times more resistant to distortions than the conventional energy-resolving circuit does under higher X-ray fluxes.

  4. Development of a single-photon-counting camera with use of a triple-stacked micro-channel plate.

    Science.gov (United States)

    Yasuda, Naruomi; Suzuki, Hitoshi; Katafuchi, Tetsuro

    2016-01-01

    At the quantum-mechanical level, all substances (not merely electromagnetic waves such as light and X-rays) exhibit wave–particle duality. Whereas students of radiation science can easily understand the wave nature of electromagnetic waves, the particle (photon) nature may elude them. Therefore, to assist students in understanding the wave–particle duality of electromagnetic waves, we have developed a photon-counting camera that captures single photons in two-dimensional images. As an image intensifier, this camera has a triple-stacked micro-channel plate (MCP) with an amplification factor of 10(6). The ultra-low light of a single photon entering the camera is first converted to an electron through the photoelectric effect on the photocathode. The electron is intensified by the triple-stacked MCP and then converted to a visible light distribution, which is measured by a high-sensitivity complementary metal oxide semiconductor image sensor. Because it detects individual photons, the photon-counting camera is expected to provide students with a complete understanding of the particle nature of electromagnetic waves. Moreover, it measures ultra-weak light that cannot be detected by ordinary low-sensitivity cameras. Therefore, it is suitable for experimental research on scintillator luminescence, biophoton detection, and similar topics.

  5. A photon counting CdTe gamma- and X-ray camera

    Science.gov (United States)

    Spartiotis, Konstantinos; Leppänen, Anssi; Pantsar, Tuomas; Pyyhtiä, Jouni; Laukka, Pasi; Muukkonen, Kari; Männistö, Olli; Kinnari, Jussi; Schulman, Tom

    2005-09-01

    A photon counting CdTe imaging camera suitable for gamma- and X-ray detection has been developed and tested. The current full active imaging area of the gamma/X-ray camera covers 44×44 mm 2. The camera is built of eight individual detector hybrids each consisting of a pixelated CdTe detector with dimensions of 22×11 mm 2 and solder bump-bonded to a photon counting custom-designed application specific integrated circuit (ASIC). The ASICs are realized in a mixed signal, 0.35 μm 4 metal 2 poly CMOS process. The effective pixel size (image pixel pitch) is 0.5 mm. To enable higher count rate imaging and to achieve better position resolution in X-ray CT scanning each pixel is divided both on the CdTe detector and on the ASIC into two sub-pixels with dimensions 0.25×0.5 mm 2. Every pixel circuit has two preamps each connected to one sub-pixel and feeding signal to a separate comparator. The digital pulses of the two distinct comparators are recorded by one common 8-bit counter. The amplifier offsets can be adjusted individually with 3-bit accuracy to compensate for process mismatch. A similar 3-bit gain tuning common to the two amplifiers in one pixel circuit is also implemented. A globally tuneable threshold voltage generated externally with high accuracy is used for energy discrimination. The camera can be operated both in the real time imaging mode with a maximum speed of 100 frames/s and in the accumulation mode with user adjustable counting time. Experimental data collected from a fully operational eight hybrid gamma/X-ray camera is presented and compared to simulated data. The camera exhibits excellent sensitivity and a dynamic range of 1:14,000,000. A sharp line spread function indicates the spatial resolution to be limited only by the pixel size (0.5 mm). A single pixel energy resolution of FWHM 4.7 keV at 122 keV (3.9%) was determined from measured 57Co spectra. The peak width of the spectrum combined from all pixels was somewhat larger due to calibration

  6. Chromatic X-ray imaging with a fine pitch CdTe sensor coupled to a large area photon counting pixel ASIC

    Science.gov (United States)

    Bellazzini, R.; Spandre, G.; Brez, A.; Minuti, M.; Pinchera, M.; Mozzo, P.

    2013-02-01

    An innovative X-ray imaging sensor based on Chromatic Photon Counting technology with intrinsic digital characteristics is presented. The system counts individually the incident X-ray photons and selects them according to their energy to produce two color images per exposure. The energy selection occurs in real time and at radiographic imaging speed (GHz global counting rate). Photon counting, color mode and a very fine spatial resolution (more than 10 LP/mm at MTF50) allow to obtain a high ratio between image quality and absorbed dose. The individual building block of the imaging system is a two-side buttable semiconductor radiation detector made of a thin pixellated CdTe crystal coupled to a large area VLSI CMOS pixel ASIC. Modules with 1, 2, 4, and 8 block units have been built. The largest module has 25 × 2.5 cm2 sensitive area. Results and images obtained from testing different modules are presented.

  7. High gain hybrid graphene-organic semiconductor phototransistors.

    Science.gov (United States)

    Huisman, Everardus H; Shulga, Artem G; Zomer, Paul J; Tombros, Nikolaos; Bartesaghi, Davide; Bisri, Satria Zulkarnaen; Loi, Maria A; Koster, L Jan Anton; van Wees, Bart J

    2015-06-03

    Hybrid phototransistors of graphene and the organic semiconductor poly(3-hexylthiophene-2,5-diyl) (P3HT) are presented. Two types of phototransistors are demonstrated with a charge carrier transit time that differs by more than 6 orders of magnitude. High transit time devices are fabricated using a photoresist-free recipe to create large-area graphene transistors made out of graphene grown by chemical vapor deposition. Low transit time devices are fabricated out of mechanically exfoliated graphene on top of mechanically exfoliated hexagonal boron nitride using standard e-beam lithography. Responsivities exceeding 10(5) A/W are obtained for the low transit time devices.

  8. A Near-Infrared Photon Counting Camera for High Sensitivity Astronomical Observation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is a Near Infrared Photon-Counting Sensor (NIRPCS), an imaging device with sufficient sensitivity to capture the spectral signatures, in the...

  9. IceBridge Photon Counting Lidar L1B Unclassified Geolocated Photon Elevations V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains geolocated photon elevations captured over Antarctica using the Sigma Space photon counting lidar. The data were collected by scientists...

  10. 4x4 Individually Addressable InGaAs APD Arrays Optimized for Photon Counting Applications

    Science.gov (United States)

    Gu, Y.; Wu, X.; Wu, S.; Choa, F. S.; Yan, F.; Shu, P.; Krainak, M.

    2007-01-01

    InGaAs APDs with improved photon counting characteristics were designed and fabricated and their performance improvements were observed. Following the results, a 4x4 individually addressable APD array was designed, fabricated, and results are reported.

  11. Turn-key Near-Infrared Photon-Counting Detector Module for LIDAR Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design and deliver a turn-key photon counting detector module for near-infrared wavelengths, based on large-area InGaAs/InP avalanche photodiodes...

  12. Turn-key Near-Infrared Photon-Counting Detector Module for LIDAR Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Based on the prototype photon counter developed during Phase I, we will deliver a next-generation photon counting detector optimized for LIDAR applications within...

  13. Highly Sensitive Photon Counting Detectors for Deep Space Optical Communications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new type of a photon-counting photodetector is proposed to advance the state-of the-art in deep space optical communications technology. The proposed detector...

  14. Photon counting imaging with an electron-bombarded CCD: Towards a parallel-processing photoelectronic time-to-amplitude converter

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M.; Jiggins, Stephen; Sergent, Nicolas; Zanda, Gianmarco; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom)

    2014-12-15

    We have used an electron-bombarded CCD for optical photon counting imaging. The photon event pulse height distribution was found to be linearly dependent on the gain voltage. We propose on this basis that a gain voltage sweep during exposure in an electron-bombarded sensor would allow photon arrival time determination with sub-frame exposure time resolution. This effectively uses an electron-bombarded sensor as a parallel-processing photoelectronic time-to-amplitude converter, or a two-dimensional photon counting streak camera. Several applications that require timing of photon arrival, including Fluorescence Lifetime Imaging Microscopy, may benefit from such an approach. A simulation of a voltage sweep performed with experimental data collected with different acceleration voltages validates the principle of this approach. Moreover, photon event centroiding was performed and a hybrid 50% Gaussian/Centre of Gravity + 50% Hyperbolic cosine centroiding algorithm was found to yield the lowest fixed pattern noise. Finally, the camera was mounted on a fluorescence microscope to image F-actin filaments stained with the fluorescent dye Alexa 488 in fixed cells.

  15. Superconductor-semiconductor interaction effects in mesoscopic hybrid structures

    Science.gov (United States)

    Rahman, F.; Thornton, T. J.; Huber, R.; Cohen, L. F.; Yuen, W. T.; Stradling, R. A.

    1996-11-01

    We have studied transport in mesoscopic superconductor-semiconductor hybrid structures consisting of two-dimensional arrays of micrometer-sized niobium dots deposited on high-mobility InAs:GaSb quantum wells. The grating arrays were designed to have a dot size and spacing of 3, 1.5, and 1 μm, so as to be smaller than the electron mean free path of ~5 μm. At low temperatures all the structures show clear evidence of Andreev reflection while the two smaller period samples also exhibit a proximity-induced superconducting phase. We present measurements of the differential resistance at different temperatures and magnetic fields. For fields greater than 0.3 T, different features are observed in the differential resistance which we attribute to nonuniform flux penetration around the superconducting dots.

  16. Extraordinary Magnetoresistance Effect in Semiconductor/Metal Hybrid Structure

    KAUST Repository

    Sun, Jian

    2013-06-27

    In this dissertation, the extraordinary magnetoresistance (EMR) effect in semiconductor/metal hybrid structures is studied to improve the performance in sensing applications. Using two-dimensional finite element simulations, the geometric dependence of the output sensitivity, which is a more relevant parameter for EMR sensors than the magnetoresistance (MR), is studied. The results show that the optimal geometry in this case is different from the geometry reported before, where the MR ratio was optimized. A device consisting of a semiconductor bar with length/width ratio of 5~10 and having only 2 contacts is found to exhibit the highest sensitivity. A newly developed three-dimensional finite element model is employed to investigate parameters that have been neglected with the two dimensional simulations utilized so far, i.e., thickness of metal shunt and arbitrary semiconductor/metal interface. The simulations show the influence of those parameters on the sensitivity is up to 10 %. The model also enables exploring the EMR effect in planar magnetic fields. In case of a bar device, the sensitivity to planar fields is about 15 % to 20 % of the one to perpendicular fields. 5 A “top-contacted” structure is proposed to reduce the complexity of fabrication, where neither patterning of the semiconductor nor precise alignment is required. A comparison of the new structure with a conventionally fabricated device shows that a similar magnetic field resolution of 24 nT/√Hz is obtained. A new 3-contact device is developed improving the poor low-field sensitivity observed in conventional EMR devices, resulting from its parabolic magnetoresistance response. The 3-contact device provides a considerable boost of the low field response by combining the Hall effect with the EMR effect, resulting in an increase of the output sensitivity by 5 times at 0.01 T compared to a 2-contact device. The results of this dissertation provide new insights into the optimization of EMR devices

  17. Impact of Compton scatter on material decomposition using a photon counting spectral detector

    Science.gov (United States)

    Lewis, Cale; Park, Chan-Soo; Fredette, Nathaniel R.; Das, Mini

    2017-03-01

    Photon counting spectral detectors are being investigated to allow better discrimination of multiple materials by collecting spectral data for every detector pixel. The process of material decomposition or discrimination starts with an accurate estimation of energy dependent attenuation of the composite object. Photoelectric effect and Compton scattering are two important constituents of the attenuation. Compton scattering while results in a loss of primary photon, also results in an increase in photon counts in the lower ene1rgy bins via multiple orders of scatter. This contribution to each energy bin may change with material properties, thickness and x-ray energies. There has been little investigation into the effect of this increase in counts at lower energies due to presence of these Compton scattered photons using photon counting detectors. Our investigations show that it is important to account for this effect in spectral decomposition problems.

  18. IceBridge Merged Photon Counting Lidar/Profiler L4 Surface Slope and Elevations V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains geolocated surface elevation measurements captured over Antarctica using the Sigma Space Mapping Photon Counting Lidar and Riegl Laser...

  19. Single Photon Counting Performance and Noise Analysis of CMOS SPAD-Based Image Sensors

    Directory of Open Access Journals (Sweden)

    Neale A. W. Dutton

    2016-07-01

    Full Text Available SPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub-electron read noise (DSERN permitting single photon counting (SPC imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width (PSW of single photon peaks in a photon counting histogram (PCH. The technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold quanta image sensor (QIS theory. Finally, various single and multiple photon spatio-temporal oversampling techniques are reviewed.

  20. Single Photon Counting Performance and Noise Analysis of CMOS SPAD-Based Image Sensors.

    Science.gov (United States)

    Dutton, Neale A W; Gyongy, Istvan; Parmesan, Luca; Henderson, Robert K

    2016-07-20

    SPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub-electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width (PSW) of single photon peaks in a photon counting histogram (PCH). The technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold quanta image sensor (QIS) theory. Finally, various single and multiple photon spatio-temporal oversampling techniques are reviewed.

  1. Photon counting passive 3D image sensing for automatic target recognition.

    Science.gov (United States)

    Yeom, Seokwon; Javidi, Bahram; Watson, Edward

    2005-11-14

    In this paper, we propose photon counting three-dimensional (3D) passive sensing and object recognition using integral imaging. The application of this approach to 3D automatic target recognition (ATR) is investigated using both linear and nonlinear matched filters. We find there is significant potential of the proposed system for 3D sensing and recognition with a low number of photons. The discrimination capability of the proposed system is quantified in terms of discrimination ratio, Fisher ratio, and receiver operating characteristic (ROC) curves. To the best of our knowledge, this is the first report on photon counting 3D passive sensing and ATR with integral imaging.

  2. Photon-counting passive 3D image sensing for reconstruction and recognition of partially occluded objects.

    Science.gov (United States)

    Yeom, Seokwon; Javidi, Bahram; Lee, Chae-Wook; Watson, Edward

    2007-11-26

    In this paper, we discuss the reconstruction and the recognition of partially occluded objects using photon counting integral imaging (II). Irradiance scenes are numerically reconstructed for the reference target in three-dimensional (3D) space. Photon counting scenes are estimated for unknown input objects using maximum likelihood estimation (MLE) of Poisson parameter. We propose nonlinear matched filtering in 3D space to recognize partially occluded targets. The recognition performance is substantially improved from the nonlinear matched filtering of elemental images without 3D reconstruction. The discrimination capability is analyzed in terms of Fisher ratio (FR) and receiver operating characteristic (ROC) curves.

  3. Exploration of maximum count rate capabilities for large-area photon counting arrays based on polycrystalline silicon thin-film transistors

    Science.gov (United States)

    Liang, Albert K.; Koniczek, Martin; Antonuk, Larry E.; El-Mohri, Youcef; Zhao, Qihua

    2016-03-01

    Pixelated photon counting detectors with energy discrimination capabilities are of increasing clinical interest for x-ray imaging. Such detectors, presently in clinical use for mammography and under development for breast tomosynthesis and spectral CT, usually employ in-pixel circuits based on crystalline silicon - a semiconductor material that is generally not well-suited for economic manufacture of large-area devices. One interesting alternative semiconductor is polycrystalline silicon (poly-Si), a thin-film technology capable of creating very large-area, monolithic devices. Similar to crystalline silicon, poly-Si allows implementation of the type of fast, complex, in-pixel circuitry required for photon counting - operating at processing speeds that are not possible with amorphous silicon (the material currently used for large-area, active matrix, flat-panel imagers). The pixel circuits of two-dimensional photon counting arrays are generally comprised of four stages: amplifier, comparator, clock generator and counter. The analog front-end (in particular, the amplifier) strongly influences performance and is therefore of interest to study. In this paper, the relationship between incident and output count rate of the analog front-end is explored under diagnostic imaging conditions for a promising poly-Si based design. The input to the amplifier is modeled in the time domain assuming a realistic input x-ray spectrum. Simulations of circuits based on poly-Si thin-film transistors are used to determine the resulting output count rate as a function of input count rate, energy discrimination threshold and operating conditions.

  4. Investigation of photon counting pixel detectors for X-ray spectroscopy and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Talla, Patrick Takoukam

    2011-04-07

    The Medipix2 and Medipix3 detectors are hybrid pixelated photon counting detectors with a pixel pitch of 55 {mu}m. The sensor material used in this thesis was silicon. Because of their small pixel size they suffer from charge sharing i.e. an incoming photon can be registered by more than one pixel. In order to correct for charge sharing due to lateral diffusion of charge carriers, the Medipix3 detector was developed: with its Charge Summing Mode, the charge collected in a cluster of 2 x 2 pixel is added up and attributed to only one pixel whose counter is incremented. The adjustable threshold of the detectors allows to count the photons and to gain information on their energy. The main purposes of the thesis are to investigate spectral and imaging properties of pixelated photon counting detectors from the Medipix family such as Medipix2 and Medipix3. The investigations are based on simulations and measurements. In order to investigate the spectral properties of the detectors measurements were performed using fluorescence lines of materials such as molybdenum, silver but also some radioactive sources such as Am-241 or Cd-109. From the measured data, parameters like the threshold dispersion and the gain variation from pixel-to-pixel were extracted and used as input in the Monte Carlo code ROSI to model the responses of the detector to monoenergetic photons. The measured data are well described by the simulations for Medipix2 and for Medipix3 operating in Charge Summing Mode. Due to charge sharing and due to the energy dependence of attenuation processes in silicon and to Compton scattering the incoming and the measured spectrum differ substantially from each other. Since the responses to monoenergetic photons are known, a deconvolution was performed to determine the true incoming spectrum. Several direct and iterative methods were successfully applied on measured and simulated data of an X-ray tube and radioactive sources. The knowledge of the X-ray spectrum is

  5. Controlled fabrication of semiconductor-metal hybrid nano-heterostructures via site-selective metal photodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Vela Becerra, Javier; Ruberu, T. Purnima A.

    2017-12-05

    A method of synthesizing colloidal semiconductor-metal hybrid heterostructures is disclosed. The method includes dissolving semiconductor nanorods in a solvent to form a nanorod solution, and adding a precursor solution to the nanorod solution. The precursor solution contains a metal. The method further includes illuminating the combined precursor and nanorod solutions with light of a specific wavelength. The illumination causes the deposition of the metal in the precursor solution onto the surface of the semiconductor nanorods.

  6. Hybrid confocal Raman fluorescence microscopy on single cells using semiconductor quantum dots

    NARCIS (Netherlands)

    van Manen, H.J.; Otto, Cornelis

    2007-01-01

    We have overcome the traditional incompatibility of Raman microscopy with fluorescence microscopy by exploiting the optical properties of semiconductor fluorescent quantum dots (QDs). Here we present a hybrid Raman fluorescence spectral imaging approach for single-cell microscopy applications. We

  7. Spectroscopic X-ray imaging with photon counting pixel detectors

    CERN Document Server

    Tlustos, L

    2010-01-01

    Single particle counting hybrid pixel detectors simultaneously provide low noise, high granularity and high readout speed and make it possible to build detector systems offering high spatial resolution paired with good energy resolution. A limiting factor for the spectroscopic performance of such detector systems is charge sharing between neighbouring pixels in the sensor part of the detector. The signal spectrum at the collection electrodes of the readout electronics deviates significantly from the photonic spectrum when planar segmented sensor geometries are used. The Medipix3 implements a novel, distributed signal processing architecture linking neighbouring pixels and aims at eliminating the spectral distortion produced in the sensor by charge sharing and at reducing the impact of fluorescence photons generated in the sensor itself. Preliminary results from the very first Medipix3 readouts bump bonded to 300 pm Si sensor are presented. Material reconstruction is a possible future application of spectrosco...

  8. Towards a miniaturized photon counting laser altimeter and stereoscopic camera instrument suite for microsatellites

    NARCIS (Netherlands)

    Moon, S.G.; Hannemann, S.; Collon, M.; Wielinga, K.; Kroesbergen, E.; Harris, J.; Gill, E.K.A.; Maessen, D.C.

    2009-01-01

    In the following we review the optimization for microsatellite deployment of a highly integrated payload suite comprising a high resolution camera, an additional camera for stereoscopic imaging, and a single photon counting laser altimeter. This payload suite, the `Stereo Imaging Laser Altimeter'

  9. Statistical evaluation of photon count rate data for nanoscale particle measurement in wastewaters.

    Science.gov (United States)

    Smeraldi, Josh; Ganesh, Rajagopalan; Safarik, Jana; Rosso, Diego

    2012-01-01

    The dynamic light scattering (DLS) technique can detect the concentration and size distribution of nanoscale particles in aqueous solutions by analyzing photon interactions. This study evaluated the applicability of using photon count rate data from DLS analyses for measuring levels of biogenic and manufactured nanoscale particles in wastewater. Statistical evaluations were performed using secondary wastewater effluent and a Malvern Zetasizer. Dynamic light scattering analyses were performed equally by two analysts over a period of two days using five dilutions and twelve replicates for each dilution. Linearity evaluation using the sixty sample analysis yielded a regression coefficient R(2) = 0.959. The accuracy analysis for various dilutions indicated a recovery of 100 ± 6%. Precision analyses indicated low variance coefficients for the impact of analysts, days, and within sample error. The variation by analysts was apparent only in the most diluted sample (intermediate precision ~12%), where the photon count rate was close to the instrument detection limit. The variation for different days was apparent in the two most concentrated samples, which indicated that wastewater samples must be analyzed for nanoscale particle measurement within the same day of collection. Upon addition of 10 mg l(-1) of nanosilica to wastewater effluent samples, the measured photon count rates were within 5% of the estimated values. The results indicated that photon count rate data can effectively complement various techniques currently available to detect nanoscale particles in wastewaters.

  10. Characterizing time decay of bibenzyl scintillator using time correlated single photon counting

    Energy Technology Data Exchange (ETDEWEB)

    Hatarik, R.; Bernstein, L. A.; Caggiano, J. A.; Carman, M. L.; Schneider, D. H. G.; Zaitseva, N. P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Wiedeking, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); iThemba LABS, P.O. Box 722, 7129 Somerset West (South Africa)

    2012-10-15

    The time decay of several scintillation materials has been measured using the time correlated single photon counting method and a new organic crystal with a highly suppressed delayed light has been identified. Results comparing the light decay of the bibenzyl crystal with a xylene based detector, which is currently installed at National Ignition Facility will be presented.

  11. Space qualified hybrid superconductor/semiconductor planar oscillator circuit

    Science.gov (United States)

    Miranda, F. A.; Chorey, C. M.; Romanofsky, R. R.; Bhasin, K. B.

    1995-01-01

    We report on the space qualification of a hybrid superconductor/semiconductor planar local oscillator (LO) at 8.4 GHz. This oscillator was designed, fabricated, and tested as a component for the High Temperature Superconductivity Space Experiment 2 (HTSSE-2). The LO consisted of a GaAs MESFET and microstrip circuitry patterned onto a YBa2Cu3O(7-delta) high temperature superconducting (HTS) thin film on a 1.0 x 1.0 sq cm lanthanum aluminate (LaAlO3) substrate. At 77 K, this oscillator achieved power output levels up to 10 dBm into a 50 Ohm load. When incorporated into a full cryogenic receiver, the LO provided output powers within 0.0-3.0 dBm with less than 50 mW of dc power dissipation. Space qualification data on the sensitivity of the HTS films to the processing steps involved in the fabrication of HTS-based components are presented. Data on ohmic contacts, strength of wire bonds made to such contacts, and aging effects as well as vibration test results are discussed.

  12. Investigation of energy weighting using an energy discriminating photon counting detector for breast CT

    Energy Technology Data Exchange (ETDEWEB)

    Kalluri, Kesava S. [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 and Biomedical Engineering and Biotechnology Program, University of Massachusetts, Lowell, One University Avenue, Lowell, Massachusetts 01854 (United States); Mahd, Mufeed [Biomedical Engineering and Biotechnology Program, University of Massachusetts, Lowell, One University Avenue, Lowell, Massachusetts 01854 (United States); Glick, Stephen J. [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States)

    2013-08-15

    Purpose: Breast CT is an emerging imaging technique that can portray the breast in 3D and improve visualization of important diagnostic features. Early clinical studies have suggested that breast CT has sufficient spatial and contrast resolution for accurate detection of masses and microcalcifications in the breast, reducing structural overlap that is often a limiting factor in reading mammographic images. For a number of reasons, image quality in breast CT may be improved by use of an energy resolving photon counting detector. In this study, the authors investigate the improvements in image quality obtained when using energy weighting with an energy resolving photon counting detector as compared to that with a conventional energy integrating detector.Methods: Using computer simulation, realistic CT images of multiple breast phantoms were generated. The simulation modeled a prototype breast CT system using an amorphous silicon (a-Si), CsI based energy integrating detector with different x-ray spectra, and a hypothetical, ideal CZT based photon counting detector with capability of energy discrimination. Three biological signals of interest were modeled as spherical lesions and inserted into breast phantoms; hydroxyapatite (HA) to represent microcalcification, infiltrating ductal carcinoma (IDC), and iodine enhanced infiltrating ductal carcinoma (IIDC). Signal-to-noise ratio (SNR) of these three lesions was measured from the CT reconstructions. In addition, a psychophysical study was conducted to evaluate observer performance in detecting microcalcifications embedded into a realistic anthropomorphic breast phantom.Results: In the energy range tested, improvements in SNR with a photon counting detector using energy weighting was higher (than the energy integrating detector method) by 30%–63% and 4%–34%, for HA and IDC lesions and 12%–30% (with Al filtration) and 32%–38% (with Ce filtration) for the IIDC lesion, respectively. The average area under the receiver

  13. Investigation of energy weighting using an energy discriminating photon counting detector for breast CT.

    Science.gov (United States)

    Kalluri, Kesava S; Mahd, Mufeed; Glick, Stephen J

    2013-08-01

    Breast CT is an emerging imaging technique that can portray the breast in 3D and improve visualization of important diagnostic features. Early clinical studies have suggested that breast CT has sufficient spatial and contrast resolution for accurate detection of masses and microcalcifications in the breast, reducing structural overlap that is often a limiting factor in reading mammographic images. For a number of reasons, image quality in breast CT may be improved by use of an energy resolving photon counting detector. In this study, the authors investigate the improvements in image quality obtained when using energy weighting with an energy resolving photon counting detector as compared to that with a conventional energy integrating detector. Using computer simulation, realistic CT images of multiple breast phantoms were generated. The simulation modeled a prototype breast CT system using an amorphous silicon (a-Si), CsI based energy integrating detector with different x-ray spectra, and a hypothetical, ideal CZT based photon counting detector with capability of energy discrimination. Three biological signals of interest were modeled as spherical lesions and inserted into breast phantoms; hydroxyapatite (HA) to represent microcalcification, infiltrating ductal carcinoma (IDC), and iodine enhanced infiltrating ductal carcinoma (IIDC). Signal-to-noise ratio (SNR) of these three lesions was measured from the CT reconstructions. In addition, a psychophysical study was conducted to evaluate observer performance in detecting microcalcifications embedded into a realistic anthropomorphic breast phantom. In the energy range tested, improvements in SNR with a photon counting detector using energy weighting was higher (than the energy integrating detector method) by 30%-63% and 4%-34%, for HA and IDC lesions and 12%-30% (with Al filtration) and 32%-38% (with Ce filtration) for the IIDC lesion, respectively. The average area under the receiver operating characteristic curve

  14. A single-photon counting “edge-on” silicon detector for synchrotron radiation mammography

    Science.gov (United States)

    Rigon, L.; Arfelli, F.; Astolfo, A.; Bergamaschi, A.; Dreossi, D.; Longo, R.; Menk, R.-H.; Schmitt, B.; Vallazza, E.; Castelli, E.

    2009-09-01

    The Phase Imaging for Clinical Application with Silicon detector and Synchrotron radiatiOn (PICASSO) project is developing an "edge-on" silicon microstrip detector for mammography with synchrotron radiation. The sensor is equipped with a fast single-photon counting electronics based on the Mythen-II application-specific integrated circuit. A first prototype has been assembled and tested at the SYnchrotron Radiation for MEdical Physics (SYRMEP) beamline at Elettra in Trieste, Italy. The first results are presented in this study including evidence of high-rate single-photon counting with negligible losses up to 1.2×10 6 incident photons per pixel per second; spatial resolution consistent with the pixel aperture (0.3 mm×0.05 mm); high-quality imaging of test-objects, obtained with a dose comparable to the one delivered in modern full-field digital mammographic systems.

  15. High-speed, FPGA-based photon-counting fluorometer with high data-gathering efficiency

    Science.gov (United States)

    Iwata, Tetsuo; Mizuno, Takahiko

    2017-07-01

    We have developed a low-cost, high-efficiency fluorometer using a field-programmable gate array and simultaneous detection of photoelectron pulse trains. The fluorometer covers a time span of 64 ns with a resolution of 1.0 ns/channel. Depending on the number of channels, the signal-gathering efficiency was improved by a factor of 100 relative to that of conventional time-correlated single-photon counting. This assumes that the fluorescence intensity is moderately high but still requires photon counting. The dead time for building a histogram has been reduced to zero, which means that the upper limit of the repetitive excitation frequency could exceed that determined by the time span. We describe instrumental details and demonstrate the basic performance.

  16. A high-throughput, multi-channel photon-counting detector with picosecond timing

    CERN Document Server

    Lapington, J S; Miller, G M; Ashton, T J R; Jarron, P; Despeisse, M; Powolny, F; Howorth, J; Milnes, J

    2009-01-01

    High-throughput photon counting with high time resolution is a niche application area where vacuum tubes can still outperform solid-state devices. Applications in the life sciences utilizing time-resolved spectroscopies, particularly in the growing field of proteomics, will benefit greatly from performance enhancements in event timing and detector throughput. The HiContent project is a collaboration between the University of Leicester Space Research Centre, the Microelectronics Group at CERN, Photek Ltd., and end-users at the Gray Cancer Institute and the University of Manchester. The goal is to develop a detector system specifically designed for optical proteomics, capable of high content (multi-parametric) analysis at high throughput. The HiContent detector system is being developed to exploit this niche market. It combines multi-channel, high time resolution photon counting in a single miniaturized detector system with integrated electronics. The combination of enabling technologies; small pore microchanne...

  17. Extending single-photon optimized superconducting transition edge sensors beyond the single-photon counting regime.

    Science.gov (United States)

    Gerrits, Thomas; Calkins, Brice; Tomlin, Nathan; Lita, Adriana E; Migdall, Alan; Mirin, Richard; Nam, Sae Woo

    2012-10-08

    Typically, transition edge sensors resolve photon number of up to 10 or 20 photons, depending on the wavelength and TES design. We extend that dynamic range up to 1000 photons, while maintaining sub-shot noise detection process uncertainty of the number of detected photons and beyond that show a monotonic response up to ≈ 6 · 10(6) photons in a single light pulse. This mode of operation, which heats the sensor far beyond its transition edge into the normal conductive regime, offers a technique for connecting single-photon-counting measurements to radiant-power measurements at picowatt levels. Connecting these two usually incompatible operating regimes in a single detector offers significant potential for directly tying photon counting measurements to conventional cryogenic radiometric standards. In addition, our measurements highlight the advantages of a photon-number state source over a coherent pulse source as a tool for characterizing such a detector.

  18. Ultrafast time measurements by time-correlated single photon counting coupled with superconducting single photon detector

    Energy Technology Data Exchange (ETDEWEB)

    Shcheslavskiy, V., E-mail: vis@becker-hickl.de; Becker, W. [Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Morozov, P.; Divochiy, A. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Vakhtomin, Yu. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Moscow State Pedagogical University, 1/1 M. Pirogovskaya St., Moscow 119991 (Russian Federation); Smirnov, K. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Moscow State Pedagogical University, 1/1 M. Pirogovskaya St., Moscow 119991 (Russian Federation); National Research University Higher School of Economics, 20 Myasnitskaya St., Moscow 101000 (Russian Federation)

    2016-05-15

    Time resolution is one of the main characteristics of the single photon detectors besides quantum efficiency and dark count rate. We demonstrate here an ultrafast time-correlated single photon counting (TCSPC) setup consisting of a newly developed single photon counting board SPC-150NX and a superconducting NbN single photon detector with a sensitive area of 7 × 7 μm. The combination delivers a record instrument response function with a full width at half maximum of 17.8 ps and system quantum efficiency ∼15% at wavelength of 1560 nm. A calculation of the root mean square value of the timing jitter for channels with counts more than 1% of the peak value yielded about 7.6 ps. The setup has also good timing stability of the detector–TCSPC board.

  19. Conjugated polymers/semiconductor nanocrystals hybrid materials--preparation, electrical transport properties and applications.

    Science.gov (United States)

    Reiss, Peter; Couderc, Elsa; De Girolamo, Julia; Pron, Adam

    2011-02-01

    This critical review discusses specific preparation and characterization methods applied to hybrid materials consisting of π-conjugated polymers (or oligomers) and semiconductor nanocrystals. These materials are of great importance in the quickly growing field of hybrid organic/inorganic electronics since they can serve as active components of photovoltaic cells, light emitting diodes, photodetectors and other devices. The electronic energy levels of the organic and inorganic components of the hybrid can be tuned individually and thin hybrid films can be processed using low cost solution based techniques. However, the interface between the hybrid components and the morphology of the hybrid directly influences the generation, separation and transport of charge carriers and those parameters are not easy to control. Therefore a large variety of different approaches for assembling the building blocks--conjugated polymers and semiconductor nanocrystals--has been developed. They range from their simple blending through various grafting procedures to methods exploiting specific non-covalent interactions between both components, induced by their tailor-made functionalization. In the first part of this review, we discuss the preparation of the building blocks (nanocrystals and polymers) and the strategies for their assembly into hybrid materials' thin films. In the second part, we focus on the charge carriers' generation and their transport within the hybrids. Finally, we summarize the performances of solar cells using conjugated polymer/semiconductor nanocrystals hybrids and give perspectives for future developments.

  20. Comparison of contrast enhancement methods using photon counting detector in spectral mammography

    Science.gov (United States)

    Kim, Hyemi; Park, Su-Jin; Jo, Byungdu; Kim, Dohyeon; Kim, Hee-Joung

    2016-03-01

    The photon counting detector with energy discrimination capabilities provides the spectral information and energy of each photon with single exposure. The energy-resolved photon counting detector makes it possible to improve the visualization of contrast agent by selecting the appropriate energy window. In this study, we simulated the photon counting spectral mammography system using a Monte Carlo method and compared three contrast enhancement methods (K-edge imaging, projection-based energy weighting imaging, and dual energy subtraction imaging). For the quantitative comparison, we used the homogeneous cylindrical breast phantom as a reference and the heterogeneous XCAT breast phantom. To evaluate the K-edge imaging methods, we obtained images by increasing the energy window width based on K-edge absorption energy of iodine. The iodine which has the K-edge discontinuity in the attenuation coefficient curve can be separated from the background. The projection-based energy weighting factor was defined as the difference in the transmissions between the contrast agent and the background. Each weighting factor as a function of photon energy was calculated and applied to the each energy bin. For the dual energy subtraction imaging, we acquired two images with below and above the iodine K-edge energy using single exposure. To suppress the breast tissue in high energy images, the weighting factor was applied as the ratio of the linear attenuation coefficients of the breast tissue at high and low energies. Our results demonstrated the CNR improvement of the K-edge imaging was the highest among the three methods. These imaging techniques based on the energy-resolved photon counting detector improved image quality with the spectral information.

  1. A Multispectral Photon-Counting Double Random Phase Encoding Scheme for Image Authentication

    Directory of Open Access Journals (Sweden)

    Faliu Yi

    2014-05-01

    Full Text Available In this paper, we propose a new method for color image-based authentication that combines multispectral photon-counting imaging (MPCI and double random phase encoding (DRPE schemes. The sparsely distributed information from MPCI and the stationary white noise signal from DRPE make intruder attacks difficult. In this authentication method, the original multispectral RGB color image is down-sampled into a Bayer image. The three types of color samples (red, green and blue color in the Bayer image are encrypted with DRPE and the amplitude part of the resulting image is photon counted. The corresponding phase information that has nonzero amplitude after photon counting is then kept for decryption. Experimental results show that the retrieved images from the proposed method do not visually resemble their original counterparts. Nevertheless, the original color image can be efficiently verified with statistical nonlinear correlations. Our experimental results also show that different interpolation algorithms applied to Bayer images result in different verification effects for multispectral RGB color images.

  2. Development of new photon-counting detectors for single-molecule fluorescence microscopy

    Science.gov (United States)

    Michalet, X.; Colyer, R. A.; Scalia, G.; Ingargiola, A.; Lin, R.; Millaud, J. E.; Weiss, S.; Siegmund, Oswald H. W.; Tremsin, Anton S.; Vallerga, John V.; Cheng, A.; Levi, M.; Aharoni, D.; Arisaka, K.; Villa, F.; Guerrieri, F.; Panzeri, F.; Rech, I.; Gulinatti, A.; Zappa, F.; Ghioni, M.; Cova, S.

    2013-01-01

    Two optical configurations are commonly used in single-molecule fluorescence microscopy: point-like excitation and detection to study freely diffusing molecules, and wide field illumination and detection to study surface immobilized or slowly diffusing molecules. Both approaches have common features, but also differ in significant aspects. In particular, they use different detectors, which share some requirements but also have major technical differences. Currently, two types of detectors best fulfil the needs of each approach: single-photon-counting avalanche diodes (SPADs) for point-like detection, and electron-multiplying charge-coupled devices (EMCCDs) for wide field detection. However, there is room for improvements in both cases. The first configuration suffers from low throughput owing to the analysis of data from a single location. The second, on the other hand, is limited to relatively low frame rates and loses the benefit of single-photon-counting approaches. During the past few years, new developments in point-like and wide field detectors have started addressing some of these issues. Here, we describe our recent progresses towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. We also discuss our development of large area photon-counting cameras achieving subnanosecond resolution for fluorescence lifetime imaging applications at the single-molecule level. PMID:23267185

  3. Development of new photon-counting detectors for single-molecule fluorescence microscopy.

    Science.gov (United States)

    Michalet, X; Colyer, R A; Scalia, G; Ingargiola, A; Lin, R; Millaud, J E; Weiss, S; Siegmund, Oswald H W; Tremsin, Anton S; Vallerga, John V; Cheng, A; Levi, M; Aharoni, D; Arisaka, K; Villa, F; Guerrieri, F; Panzeri, F; Rech, I; Gulinatti, A; Zappa, F; Ghioni, M; Cova, S

    2013-02-05

    Two optical configurations are commonly used in single-molecule fluorescence microscopy: point-like excitation and detection to study freely diffusing molecules, and wide field illumination and detection to study surface immobilized or slowly diffusing molecules. Both approaches have common features, but also differ in significant aspects. In particular, they use different detectors, which share some requirements but also have major technical differences. Currently, two types of detectors best fulfil the needs of each approach: single-photon-counting avalanche diodes (SPADs) for point-like detection, and electron-multiplying charge-coupled devices (EMCCDs) for wide field detection. However, there is room for improvements in both cases. The first configuration suffers from low throughput owing to the analysis of data from a single location. The second, on the other hand, is limited to relatively low frame rates and loses the benefit of single-photon-counting approaches. During the past few years, new developments in point-like and wide field detectors have started addressing some of these issues. Here, we describe our recent progresses towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. We also discuss our development of large area photon-counting cameras achieving subnanosecond resolution for fluorescence lifetime imaging applications at the single-molecule level.

  4. Update on Linear Mode Photon Counting with the HgCdTe Linear Mode Avalanche Photodiode

    Science.gov (United States)

    Beck, Jeffrey D.; Kinch, Mike; Sun, Xiaoli

    2014-01-01

    The behavior of the gain-voltage characteristic of the mid-wavelength infrared cutoff HgCdTe linear mode avalanche photodiode (e-APD) is discussed both experimentally and theoretically as a function of the width of the multiplication region. Data are shown that demonstrate a strong dependence of the gain at a given bias voltage on the width of the n- gain region. Geometrical and fundamental theoretical models are examined to explain this behavior. The geometrical model takes into account the gain-dependent optical fill factor of the cylindrical APD. The theoretical model is based on the ballistic ionization model being developed for the HgCdTe APD. It is concluded that the fundamental theoretical explanation is the dominant effect. A model is developed that combines both the geometrical and fundamental effects. The model also takes into account the effect of the varying multiplication width in the low bias region of the gain-voltage curve. It is concluded that the lower than expected gain seen in the first 2 × 8 HgCdTe linear mode photon counting APD arrays, and higher excess noise factor, was very likely due to the larger than typical multiplication region length in the photon counting APD pixel design. The implications of these effects on device photon counting performance are discussed.

  5. Beam driven upper-hybrid-wave instability in quantized semiconductor plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, M. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Rasheed, A. [Department of Physics, Government College University, Faisalabad 38000 (Pakistan); Rozina, Ch. [Department of Physics, Government M.A.O. College, Lahore 54000 (Pakistan); Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); Centre for Theoretical Physics, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt); Salimullah, M. [Department of Physics, Jahangirnagar University, Savar, Dhaka 1342 (Bangladesh)

    2014-02-15

    The excitation of Upper-Hybrid waves (UHWs) induced by electron beam in semiconductor plasma is examined using quantum hydrodynamic model. Various quantum effects are taken into account including recoil effect, Fermi degenerate pressure, and exchange-correlation potential. The bandwidth of the UHWs spectrum shows that the system supports purely growing unstable mode. The latter has been studied for diversified parameters of nano-sized GaAs semiconductor.

  6. Low-noise low-jitter 32-pixels CMOS single-photon avalanche diodes array for single-photon counting from 300 nm to 900 nm

    Energy Technology Data Exchange (ETDEWEB)

    Scarcella, Carmelo; Tosi, Alberto, E-mail: alberto.tosi@polimi.it; Villa, Federica; Tisa, Simone; Zappa, Franco [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy)

    2013-12-15

    We developed a single-photon counting multichannel detection system, based on a monolithic linear array of 32 CMOS SPADs (Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Diodes). All channels achieve a timing resolution of 100 ps (full-width at half maximum) and a photon detection efficiency of 50% at 400 nm. Dark count rate is very low even at room temperature, being about 125 counts/s for 50 μm active area diameter SPADs. Detection performance and microelectronic compactness of this CMOS SPAD array make it the best candidate for ultra-compact time-resolved spectrometers with single-photon sensitivity from 300 nm to 900 nm.

  7. Improved Semiconductor Lattice Parameters and Band Gaps from a Middle-Range Screened Hybrid Functional

    OpenAIRE

    Lucero, Melissa J.; Henderson, Thomas M.; Scuseria, Gustavo E.

    2011-01-01

    We show that the middle-range exchange-correlation hybrid of Henderson, Izmaylov, Scuseria and Savin (HISS) performs extremely well for elemental and binary semiconductors with narrow or visible spectrum band gaps, as well as some wider gap or more ionic systems used commercially. The lattice parameters are superior to those predicted by the screened hybrid functional of Heyd, Scuseria and Ernzerhof (HSE), and provide a significant improvement over geometries predicted by semilocal functional...

  8. Dear-Mama: A photon counting X-ray imaging project for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Blanchot, G. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Chmeissani, M. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain)]. E-mail: mokhtar@ifae.es; Diaz, A. [Sedecal SA, C/ Pelaya 9, Pol. Ind. Rio de Janeiro, 28110 Algete (Spain); Diaz, F. [Sedecal SA, C/ Pelaya 9, Pol. Ind. Rio de Janeiro, 28110 Algete (Spain); Fernandez, J. [UDIAT, Corporacion Sanitaria Parc Tauli, s/n. 08208-Sabadell (Spain); Garcia, E. [Sedecal SA, C/ Pelaya 9, Pol. Ind. Rio de Janeiro, 28110 Algete (Spain); Garcia, J. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Kainberger, F. [Medical University of Vienna AKH, A-1090 Vienna (Austria); Lozano, M. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain); Maiorino, M. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Martinez, R. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain); Montagne, J.P. [Hopital D' enfants Armand Trousseau, 75571 Paris Cedex (France); Moreno, I. [Sedecal SA, C/ Pelaya 9, Pol. Ind. Rio de Janeiro, 28110 Algete (Spain); Pellegrini, G. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain); Puigdengoles, C. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Sentis, M. [UDIAT, Corporacion Sanitaria Parc Tauli, s/n. 08208-Sabadell (Spain); Teres, L. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain); Tortajada, M. [UDIAT, Corporacion Sanitaria Parc Tauli, s/n. 08208-Sabadell (Spain); Ullan, M. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain)

    2006-12-10

    Dear-Mama (Detection of Early Markers in Mammography) is an EU funded project devoted to develop an X-ray Medical imaging device based on room temperature solid-state pixel detector coupled to photon counting readout electronics via bump bonding. The technology being used leads to signal-to-noise ratio enhancement and thus the ability to detect low contrast anomalies such as micro-calcifications. The Dear-Mama machine is currently being evaluated and preliminary results show an excellent MTF response. Dear-Mama consortium is made up from six European institutions, the project runs from December 2001 to March 2006.

  9. Wide-field single photon counting imaging with an ultrafast camera and an image intensifier

    Energy Technology Data Exchange (ETDEWEB)

    Zanda, Gianmarco, E-mail: gianmarco.zanda@kcl.ac.uk [King' s College London, Department of Physics, Strand, London WC2R 2LS (United Kingdom); Sergent, Nicolas; Green, Mark; Levitt, James A. [King' s College London, Department of Physics, Strand, London WC2R 2LS (United Kingdom); Petrasek, Zdenek [Biotechnologisches Zentrum, Technische Universitaet Dresden, Tatzberg 47/49, 01307 Dresden (Germany); Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [King' s College London, Department of Physics, Strand, London WC2R 2LS (United Kingdom)

    2012-12-11

    We are reporting a method for wide-field photon counting imaging using a CMOS camera with a 40 kHz frame rate coupled with a three-stage image intensifier mounted on a standard fluorescence microscope. This system combines high frame rates with single photon sensitivity. The output of the phosphor screen, consisting of single-photon events, is collected by a CMOS camera allowing to create a wide-field image with parallel positional and timing information of each photon. Using a pulsed excitation source and a luminescent sample, the arrival time of hundreds of photons can be determined simultaneously in many pixels with microsecond resolution.

  10. A miniaturized 4 K platform for superconducting infrared photon counting detectors

    Science.gov (United States)

    Gemmell, Nathan R.; Hills, Matthew; Bradshaw, Tom; Rawlings, Tom; Green, Ben; Heath, Robert M.; Tsimvrakidis, Konstantinos; Dobrovolskiy, Sergiy; Zwiller, Val; Dorenbos, Sander N.; Crook, Martin; Hadfield, Robert H.

    2017-11-01

    We report on a miniaturized platform for superconducting infrared photon counting detectors. We have implemented a fibre-coupled superconducting nanowire single photon detector in a Stirling/Joule-Thomson platform with a base temperature of 4.2 K. We have verified a cooling power of 4 mW at 4.7 K. We report 20% system detection efficiency at 1310 nm wavelength at a dark count rate of 1 kHz. We have carried out compelling application demonstrations in single photon depth metrology and singlet oxygen luminescence detection.

  11. Time-gating scheme based on a photodiode for single-photon counting

    Science.gov (United States)

    Kumavor, Patrick D.; Tavakoli, Behnoosh; Donkor, Eric; Zhu, Quing

    2012-01-01

    A fast, simple, and low-cost optical time-gating scheme for counting single photons is presented. Its construction consists of a silicon photodiode connected in series with a 50 Ω resistor and that operates in the photoconductive mode. The temporal resolution at the FWHM of the photon counting system was measured to be 62 ps. The profile of a single-photon pulse measured with the counting system agreed well with analytical results. The system was also used to successfully resolve a pair of targets with 4 mm separation inside a highly scattering medium by the use of time-gated early-arriving photons. PMID:21725458

  12. Manipulating and probing microwave fields in a cavity by quantum non-demolition photon counting

    Energy Technology Data Exchange (ETDEWEB)

    Haroche, S; Dotsenko, I; Deleglise, S; Sayrin, C; Zhou, X; Gleyzes, S; Guerlin, C; Kuhr, S; Brune, M; Raimond, J-M [Laboratoire Kastler Brossel, Departement de Physique de l' Ecole Normale Superieure, CNRS and Universite Pierre et Marie Curie, 24 rue Lhomond, 75231 Paris Cedex 05 (France)], E-mail: haroche@lkb.ens.fr

    2009-12-15

    We perform quantum non-demolition (QND) photon counting on a microwave field trapped in a very high Q superconducting cavity, employing circular Rydberg atoms as non-absorbing light probes. Beyond realizing fundamental tests of quantum measurement theory, we use this QND method to prepare non-classical Fock and Schroedinger cat states of the field and to reconstruct their Wigner functions. Monitoring the evolution of these functions provides a direct observation of the decoherence process. Quantum feedback procedures will enable us to steer the field towards target states and to protect them against decoherence.

  13. Manipulating and probing microwave fields in a cavity by quantum non-demolition photon counting

    Science.gov (United States)

    Haroche, S.; Dotsenko, I.; Deléglise, S.; Sayrin, C.; Zhou, X.; Gleyzes, S.; Guerlin, C.; Kuhr, S.; Brune, M.; Raimond, J.-M.

    2009-12-01

    We perform quantum non-demolition (QND) photon counting on a microwave field trapped in a very high Q superconducting cavity, employing circular Rydberg atoms as non-absorbing light probes. Beyond realizing fundamental tests of quantum measurement theory, we use this QND method to prepare non-classical Fock and Schrödinger cat states of the field and to reconstruct their Wigner functions. Monitoring the evolution of these functions provides a direct observation of the decoherence process. Quantum feedback procedures will enable us to steer the field towards target states and to protect them against decoherence.

  14. Wide-field single photon counting imaging with an ultrafast camera and an image intensifier

    Science.gov (United States)

    Zanda, Gianmarco; Sergent, Nicolas; Green, Mark; Levitt, James A.; Petrášek, Zdeněk; Suhling, Klaus

    2012-12-01

    We are reporting a method for wide-field photon counting imaging using a CMOS camera with a 40 kHz frame rate coupled with a three-stage image intensifier mounted on a standard fluorescence microscope. This system combines high frame rates with single photon sensitivity. The output of the phosphor screen, consisting of single-photon events, is collected by a CMOS camera allowing to create a wide-field image with parallel positional and timing information of each photon. Using a pulsed excitation source and a luminescent sample, the arrival time of hundreds of photons can be determined simultaneously in many pixels with microsecond resolution.

  15. Teleportation of a unknown coherent-state superposition within a network without photon counting

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Ba An [Institute for Theoretical Physics 1, Stuttgart University, Pfaffenwaldring 57/4, D-70550 Stuttgart (Germany) and Institute of Physics and Electronics, 10 Dao Tan, Thu Le, Ba Dinh, Hanoi (Viet Nam)]. E-mail: nban@iop.vast.ac.vn; Mahler, Guenter [Institute for Theoretical Physics 1, Stuttgart University, Pfaffenwaldring 57/4, D-70550 Stuttgart (Germany)

    2007-05-21

    A new experimental scheme to teleport a unknown superposition of two coherent states with an equal amplitude but opposite phases between two parties under control of a number of controllers is proposed using only 'yes/no' detectors, i.e., without photon counting. The protocol is conclusive in the sense that any party is able to recognize a failure or a possible success immediately after his measurement. The total success probability is derived which yields a maximal value of 1/2 independent of the number of controllers.

  16. Near UV imager with an MCP-based photon counting detector

    Science.gov (United States)

    Ambily, S.; Mathew, Joice; Sarpotdar, Mayuresh; Sreejith, A. G.; Nirmal, K.; Prakash, Ajin; Safonova, Margarita; Murthy, Jayant

    2016-07-01

    We are developing a compact UV Imager using light weight components, that can be own on a small CubeSat or a balloon platform. The system has a lens-based optics that can provide an aberration-free image over a wide field of view. The backend instrument is a photon counting detector with off-the-shelf MCP, CMOS sensor and electronics. We are using a Z-stack MCP with a compact high voltage power supply and a phosphor screen anode, which is read out by a CMOS sensor and the associated electronics. The instrument can be used to observe solar system objects and detect bright transients from the upper atmosphere with the help of CubeSats or high altitude balloons. We have designed the imager to be capable of working in direct frame transfer mode as well in the photon-counting mode for single photon event detection. The identification and centroiding of each photon event are done using an FPGA-based data acquisition and real-time processing system.

  17. Estimation of signal and noise for a whole-body research photon-counting CT system.

    Science.gov (United States)

    Li, Zhoubo; Leng, Shuai; Yu, Zhicong; Kappler, Steffen; McCollough, Cynthia H

    2017-04-01

    Photon-counting detector CT has a large number of acquisition parameters that require optimization, particularly the energy threshold configurations. Fast and accurate estimation of both signal and noise in photon-counting CT (PCCT) images can facilitate such optimization. Using the detector response function of a research PCCT system, we derived mathematical models for both signal and noise estimation, taking into account beam spectrum and filtration, object attenuation, water beam hardening, detector response, radiation dose, energy thresholds, and the propagation of noise. To determine the absolute noise value, a noise lookup table (LUT) for all available energy thresholds was acquired using a number of calibration scans. The noise estimation algorithm then used the noise LUT to estimate noise for scans with a variety of combination of energy thresholds, dose levels, and object attenuations. Validation of the estimation algorithms was performed on a whole-body research PCCT system using semianthropomorphic water phantoms and solutions of calcium and iodine. Clinical feasibility of noise estimation was assessed with scans of a cadaver head and a living swine. The algorithms achieved accurate estimation of both signal and noise for a variety of scanning parameter combinations. Maximum discrepancies were below 15%, while most errors were below 5%.

  18. A technology review of time-of-flight photon counting for advanced remote sensing

    Science.gov (United States)

    Lamb, Robert A.

    2010-04-01

    Time correlated single photon counting (TCSPC) has made tremendous progress during the past ten years enabling improved performance in precision time-of-flight (TOF) rangefinding and lidar. In this review the development and performance of several ranging systems is presented that use TCSPC for accurate ranging and range profiling over distances up to 17km. A range resolution of a few millimetres is routinely achieved over distances of several kilometres. These systems include single wavelength devices operating in the visible; multi-wavelength systems covering the visible and near infra-red; the use of electronic gating to reduce in-band solar background and, most recently, operation at high repetition rates without range aliasing- typically 10MHz over several kilometres. These systems operate at very low optical power (military, security and surveillance sensing applications. The review will highlight the theoretical principles of photon counting and progress made in developing absolute ranging techniques that enable high repetition rate data acquisition that avoids range aliasing. Technology trends in TCSPC rangefinding are merging with those of quantum cryptography and its future application to revolutionary quantum imaging provides diverse and exciting research into secure covert sensing, ultra-low power active imaging and quantum rangefinding.

  19. Experimental study of beam hardening artifacts in photon counting breast computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bisogni, M.G.; Del Guerra, A. [Dip. di Fisica, Univ. di Pisa and INFN, Pisa (Italy); Lanconelli, N. [Dip. di Fisica, Univ. di Bologna and INFN, Bologna (Italy); Lauria, A.; Mettivier, G. [Dip. di Scienze Fisiche, Univ. di Napoli Federico II and INFN, Naples (Italy); Montesi, M.C. [Dip. di Scienze Fisiche, Univ. di Napoli Federico II and INFN, Naples (Italy)], E-mail: montesi@na.infn.it; Panetta, D. [Dip. di Fisica, Univ. di Pisa and INFN, Pisa (Italy); Pani, R. [Dip. di Medicina Sperimentale, Univ. La Sapienza and INFN, Rome (Italy); Quattrocchi, M.G. [Dip. di Fisica, Univ. di Pisa and INFN, Pisa (Italy); Randaccio, P. [Dip. di Fisica, Univ. di Cagliari and INFN, Cagliari (Italy); Rosso, V. [Dip. di Fisica, Univ. di Pisa and INFN, Pisa (Italy); Russo, P. [Dip. di Scienze Fisiche, Univ. di Napoli Federico II and INFN, Naples (Italy)

    2007-10-21

    We are implementing an X-ray breast Computed Tomography (CT) system on the gantry of a dedicated single photon emission tomography system for breast Tc-99 imaging. For the breast CT system we investigated the relevance of the beam hardening artifact. We studied the use of a single photon counting silicon pixel detector (0.3 mm thick, 256x256 pixel, 55{mu}m pitch, bump-bonded to the Medipix2 photon counting readout chip) as detector unit in our X-ray CT system. We evaluated the beam hardening 'cupping' artifact using homogeneous PMMA slabs and phantoms up to 14 cm in diameter, used as uncompressed breast tissue phantoms, imaged with a tungsten anode tube at 80 kVp with 4.2 mm Al filtration. For beam hardening evaluation we used a bimodal energy model. The CT data show a 'cupping' artifact going from 4% (4-cm thick material) to 18% (14-cm thick material). This huge artifacts is influenced by the low detection efficiency and the charge sharing effect of the silicon pixel detector.

  20. Sequential data assimilation for single-molecule FRET photon-counting data

    Energy Technology Data Exchange (ETDEWEB)

    Matsunaga, Yasuhiro [Advanced Institute for Computational Science, RIKEN, 7-1-26 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047 (Japan); Kidera, Akinori [Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi, Yokohama 230-0045 (Japan); Sugita, Yuji, E-mail: sugita@riken.jp [Advanced Institute for Computational Science, RIKEN, 7-1-26 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047 (Japan); Theoretical Molecular Science Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); iTHES, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Quantitative Biology Center, RIKEN, International Medical Device Alliance (IMDA) 6F, 1-6-5 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047 (Japan)

    2015-06-07

    Data assimilation is a statistical method designed to improve the quality of numerical simulations in combination with real observations. Here, we develop a sequential data assimilation method that incorporates one-dimensional time-series data of smFRET (single-molecule Förster resonance energy transfer) photon-counting into conformational ensembles of biomolecules derived from “replicated” molecular dynamics (MD) simulations. A particle filter using a large number of “replicated” MD simulations with a likelihood function for smFRET photon-counting data is employed to screen the conformational ensembles that match the experimental data. We examine the performance of the method using emulated smFRET data and coarse-grained (CG) MD simulations of a dye-labeled polyproline-20. The method estimates the dynamics of the end-to-end distance from smFRET data as well as revealing that of latent conformational variables. The particle filter is also able to correct model parameter dependence in CG MD simulations. We discuss the applicability of the method to real experimental data for conformational dynamics of biomolecules.

  1. Time transfer capability of standard small form factor pluggable laser modules based on photon counting approach

    Science.gov (United States)

    Trojanek, Pavel; Prochazka, Ivan; Blazej, Josef

    2017-05-01

    We are reporting on timing parameters of commonly used standard Small Form Factor Pluggable (SFP) laser modules using single photon counting method. Photon counting is a promising approach for laser time transfer via optical fiber communication hardware. The sub-picosecond precision and stability may be achieved. We have performed several experiments with the aim to measure main parameters of the modules, such as time delay precision, time stability and temperature stability, all being critical for optical time transfer applications. Two standard 16 and 10 Gbit/s at 850 nm SFP modules were examined. The ultimate precision of possible time transfer of 800 fs for averaging times of hours was achieved. The modules together with their driving circuits exhibited very good temperature stability. The temperature drift as low as 300+/-200 fs/K was measured. The achieved timing parameters will enable to use the standard SFP modules for a new method of two way time transfer where the time differences between two distant time scales are measured in parallel to data transfer on existing optical data links without any communication interference.

  2. Photon-counting 1.0 GHz-phase-modulation fluorometer

    Science.gov (United States)

    Mizuno, T.; Nakao, S.; Mizutani, Y.; Iwata, T.

    2015-04-01

    We have constructed an improved version of a photon-counting phase-modulation fluorometer (PC-PMF) with a maximum modulation frequency of 1.0 GHz, where a phase domain measurement is conducted with a time-correlated single-photon-counting electronics. While the basic concept of the PC-PMF has been reported previously by one of the authors, little attention has been paid to its significance, other than its weak fluorescence measurement capability. Recently, we have recognized the importance of the PC-PMF and its potential for fluorescence lifetime measurements. One important aspect of the PC-PMF is that it enables us to perform high-speed measurements that exceed the frequency bandwidths of the photomultiplier tubes that are commonly used as fluorescence detectors. We describe the advantages of the PC-PMF and demonstrate its usefulness based on fundamental performance tests. In our new version of the PC-PMF, we have used a laser diode (LD) as an excitation light source rather than the light-emitting diode that was used in the primary version. We have also designed a simple and stable LD driver to modulate the device. Additionally, we have obtained a sinusoidal histogram waveform that has multiple cycles within a time span to be measured, which is indispensable for precise phase measurements. With focus on the fluorescence intensity and the resolution time, we have compared the performance of the PC-PMF with that of a conventional PMF using the analogue light detection method.

  3. Polarimetric, Two-Color, Photon-Counting Laser Altimeter Measurements of Forest Canopy Structure

    Science.gov (United States)

    Harding, David J.; Dabney, Philip W.; Valett, Susan

    2011-01-01

    Laser altimeter measurements of forest stands with distinct structures and compositions have been acquired at 532 nm (green) and 1064 nm (near-infrared) wavelengths and parallel and perpendicular polarization states using the Slope Imaging Multi-polarization Photon Counting Lidar (SIMPL). The micropulse, single photon ranging measurement approach employed by SIMPL provides canopy structure measurements with high vertical and spatial resolution. Using a height distribution analysis method adapted from conventional, 1064 nm, full-waveform lidar remote sensing, the sensitivity of two parameters commonly used for above-ground biomass estimation are compared as a function of wavelength. The results for the height of median energy (HOME) and canopy cover are for the most part very similar, indicating biomass estimations using lidars operating at green and near-infrared wavelengths will yield comparable estimates. The expected detection of increasing depolarization with depth into the canopies due to volume multiple-scattering was not observed, possibly due to the small laser footprint and the small detector field of view used in the SIMPL instrument. The results of this work provide pathfinder information for NASA's ICESat-2 mission that will employ a 532 nm, micropulse, photon counting laser altimeter.

  4. Feasibility study of a breast density measurement within a direct photon-counting mammography scanner system.

    Science.gov (United States)

    Machida, Youichi; Tozaki, Mitsuhiro; Yoshida, Tamiko; Saita, Ai; Yakabe, Mari; Nii, Kanae

    2014-09-01

    To evaluate the clinical feasibility of breast density measurements by a new application within a direct photon-counting mammography scanner system. A retrospective study of consecutive women who underwent mammography using a direct photon-counting mammography scanner system (MicroDose mammography SI; Philips Digital Mammography Sweden AB) was performed at the authors' institution between September and December 2013. Quantitative volumetric glandularity measurements were performed automatically for each acquired mammographic image using an application (Breast Density Measurement; Philips Digital Mammography Sweden AB). The quantitative volumetric glandularity of each breast was defined as the average values for the mediolateral oblique (MLO) and craniocaudal (CC) mammogram views. Of the 44 women who underwent bilateral mammogram acquisitions, the breast density measurements were performed successfully in 40 patients (90.9%). A very good to excellent correlation in the quantitative breast density measurements acquired from the MLO and CC images was obtained in the 40 evaluable patients (R = 0.99). The calculated volumetric glandularity using this new application should correspond well with the true volumetric density of each breast.

  5. Beam hardening artefacts in computed tomography with photon counting, charge integrating and energy weighting detectors: a simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Shikhaliev, Polad M [Department of Radiological Sciences, University of California, Irvine, CA 92697 (United States)

    2005-12-21

    Photon counting x-ray imaging provides efficient rejection of the electronics noise, no pulse height (Swank) noise, less noise due to optimal photon energy weighting and the possibility of energy resolved image acquisition. These advantages apply also to CT when projection data are acquired using a photon counting detector. However, photon counting detectors assign a weighting factor of 1 to all detected photons whereas the weighting factor of a charge integrating detector is proportional to the energy of the detected photon. Therefore, data collected by photon counting and charge integrating detectors represent the 'hardening' of the photon beam passed through the object differently. This affects the beam hardening artefacts in the reconstructed CT images. This work represents the first comparative evaluation of the effect of photon counting, charge integrating and energy weighting photon detectors on beam hardening artefacts in CT. Beam hardening artefacts in CT images were evaluated for 20 cm and 14 cm diameter water cylinders with bone and low contrast inserts, at 120 kVp and 90 kVp x-ray tube voltages, respectively. It was shown that charge integrating results in 1.8% less beam hardening artefacts from bone inserts (i.e., CT numbers in the 'shadow' of the bone are less by 1.8% as compared to CT numbers over the periphery of the image), as compared to photon counting. However, optimal photon energy weighting, which provides highest SNR, results in 7.7% higher beam hardening artefacts from bone inserts as compared to photon counting. The magnitude of the 'cupping' artefacts was lower by 1% for charge integrating and higher by 6.1% for energy weighting acquisitions as compared to photon counting. Only the photon counting systems provide an accurate representation of the beam hardening effect due to its flat energy weighting. Because of their energy dependent weighting factors, the charge integrating and energy weighting systems do

  6. Graphene-Insulator-Semiconductor Junction for Hybrid Photodetection Modalities.

    Science.gov (United States)

    Howell, Stephen W; Ruiz, Isaac; Davids, Paul S; Harrison, Richard K; Smith, Sean W; Goldflam, Michael D; Martin, Jeffrey B; Martinez, Nicholas J; Beechem, Thomas E

    2017-11-07

    A sensitive optical detector is presented based on a deeply depleted graphene-insulator-semiconducting (D(2)GIS) junction, which offers the possibility of simultaneously leveraging the advantages of both charge integration and localized amplification. Direct read-out and built-in amplification are accomplished via photogating of a graphene field-effect transistor (GFET) by carriers generated within a deeply depleted low-doped silicon substrate. Analogous to a depleted metal-oxide-semiconducting junction, photo-generated charge collects in the potential well that forms at the semiconductor/insulator interface and induces charges of opposite polarity within the graphene film modifying its conductivity. This device enables simultaneous photo-induced charge integration with continuous "on detector" readout through use of graphene. The resulting devices exhibit responsivities as high as 2,500 A/W (25,000 S/W) for visible wavelengths and a dynamic range of 30 dB. As both the graphene and device principles are transferrable to arbitrary semiconductor absorbers, D(2)GIS devices offer a high-performance paradigm for imaging across the electromagnetic spectrum.

  7. Nanoscale semiconductor hybrids: fundamental physics and advanced devices

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Binh-Minh [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-04-09

    Key summary: Low dimensional hybrids: more flexibility and better controllability of materials properties. Type-II Antimonide-based superlattice: system of interacting quantum wells, for infrared detection and imaging. Hetero-designs in core/multi-shell nanowires: promising candidate for high performance electronic and sensing applications. An interdisciplinary research plan could trigger interest and collaboration within RIT.

  8. Advances and Promises of Layered Halide Hybrid Perovskite Semiconductors

    NARCIS (Netherlands)

    Pedesseau, Laurent; Sapori, Daniel; Traore, Boubacar; Robles, Roberto; Fang, Hong-Hua; Loi, Maria Antonietta; Tsai, Hsinhan; Nie, Wanyi; Blancon, Jean-Christophe; Neukirch, Amanda; Tretiak, Sergei; Mohite, Aditya D.; Katan, Claudine; Even, Jacky; Kepenekian, Mikael

    2016-01-01

    Layered halide hybrid organic inorganic perovskites (HOP) have been the subject of intense investigation before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells

  9. Advances and Promises of Layered Halide Hybrid Perovskite Semiconductors

    NARCIS (Netherlands)

    Pedesseau, Laurent; Sapori, Daniel; Traore, Boubacar; Robles, Roberto; Fang, Hong-Hua; Loi, Maria Antonietta; Tsai, Hsinhan; Nie, Wanyi; Blancon, Jean-Christophe; Neukirch, Amanda; Tretiak, Sergei; Mohite, Aditya D.; Katan, Claudine; Even, Jacky; Kepenekian, Mikael

    Layered halide hybrid organic inorganic perovskites (HOP) have been the subject of intense investigation before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells

  10. Signal to noise ratio of energy selective x-ray photon counting systems with pileup.

    Science.gov (United States)

    Alvarez, Robert E

    2014-11-01

    To derive fundamental limits on the effect of pulse pileup and quantum noise in photon counting detectors on the signal to noise ratio (SNR) and noise variance of energy selective x-ray imaging systems. An idealized model of the response of counting detectors to pulse pileup is used. The model assumes a nonparalyzable response and delta function pulse shape. The model is used to derive analytical formulas for the noise and energy spectrum of the recorded photons with pulse pileup. These formulas are first verified with a Monte Carlo simulation. They are then used with a method introduced in a previous paper [R. E. Alvarez, "Near optimal energy selective x-ray imaging system performance with simple detectors," Med. Phys. 37, 822-841 (2010)] to compare the signal to noise ratio with pileup to the ideal SNR with perfect energy resolution. Detectors studied include photon counting detectors with pulse height analysis (PHA), detectors that simultaneously measure the number of photons and the integrated energy (NQ detector), and conventional energy integrating and photon counting detectors. The increase in the A-vector variance with dead time is also computed and compared to the Monte Carlo results. A formula for the covariance of the NQ detector is developed. The validity of the constant covariance approximation to the Cramèr-Rao lower bound (CRLB) for larger counts is tested. The SNR becomes smaller than the conventional energy integrating detector (Q) SNR for 0.52, 0.65, and 0.78 expected number photons per dead time for counting (N), two, and four bin PHA detectors, respectively. The NQ detector SNR is always larger than the N and Q SNR but only marginally so for larger dead times. Its noise variance increases by a factor of approximately 3 and 5 for the A1 and A2 components as the dead time parameter increases from 0 to 0.8 photons per dead time. With four bin PHA data, the increase in variance is approximately 2 and 4 times. The constant covariance approximation

  11. Dual energy CT with photon counting and dual source systems: comparative evaluation.

    Science.gov (United States)

    Atak, Haluk; Shikhaliev, Polad M

    2015-12-07

    Recently, new dual energy (DE) computed tomography (CT) systems-dual source CT (DSCT) and photon counting CT (PCCT) have been introduced. Although these systems have the same clinical targets, they have major differences as they use dual and single kVp acquisitions and different x-ray detection and energy resolution concepts. The purpose of this study was theoretical and experimental comparisons of DSCT and PCCT. The DSCT Siemens Somatom Flash was modeled for simulation study. The PCCT had the same configuration as DSCT except it used a photon counting detector. The soft tissue phantoms with 20, 30, and 38 cm diameters included iodine, CaCO3, adipose, and water samples. The dose (air kerma) was 14 mGy for all studies. The low and high energy CT data were simulated at 80 kVp and 140 kVp for DSCT, and in 20-58 keV and 59-120 keV energy ranges for PCCT, respectively. The experiments used Somatom Flash DSCT system and PCCT system based on photon counting CdZnTe detector with 2  ×  256 pixel configuration and 1  ×  1 mm(2) pixels size. In simulated general CT images, PCCT provided higher contrast-to-noise ratio (CNR) than DSCT with 0.4/0.8 mm Sn filters. The PCCT with K-edge filter provided higher CNR than the PCCT with a Cu filter, and DSCT with 0.4 mm Sn filter provided higher CNR than the DSCT with a 0.8 mm Sn filter. In simulated DE subtracted images, CNR of the DSCT was comparable to the PCCT with a Cu filter. However, DE PCCT with Ho a K-edge filter provided 30-40% higher CNR than the DE DSCT with 0.4/0.8 mm Sn filters. The experimental PCCT provided higher CNR in general imaging compared to the DSCT. In experimental DE subtracted images, the DSCT provided higher CNR than the PCCT with a Cu filter. However, experimental CNR with DE PCCT with K-edge filter was 15% higher than in DE DSCT, which is less than 30-40% increase predicted by the simulation study. It is concluded that ideal PCCT can provide substantial advantages over ideal

  12. Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging

    Science.gov (United States)

    Iwanczyk, Jan S.; Nygård, Einar; Meirav, Oded; Arenson, Jerry; Barber, William C.; Hartsough, Neal E.; Malakhov, Nail; Wessel, Jan C.

    2009-01-01

    The development of an innovative detector technology for photon-counting in X-ray imaging is reported. This new generation of detectors, based on pixellated cadmium telluride (CdTe) and cadmium zinc telluride (CZT) detector arrays electrically connected to application specific integrated circuits (ASICs) for readout, will produce fast and highly efficient photon-counting and energy-dispersive X-ray imaging. There are a number of applications that can greatly benefit from these novel imagers including mammography, planar radiography, and computed tomography (CT). Systems based on this new detector technology can provide compositional analysis of tissue through spectroscopic X-ray imaging, significantly improve overall image quality, and may significantly reduce X-ray dose to the patient. A very high X-ray flux is utilized in many of these applications. For example, CT scanners can produce ~100 Mphotons/mm2/s in the unattenuated beam. High flux is required in order to collect sufficient photon statistics in the measurement of the transmitted flux (attenuated beam) during the very short time frame of a CT scan. This high count rate combined with a need for high detection efficiency requires the development of detector structures that can provide a response signal much faster than the transit time of carriers over the whole detector thickness. We have developed CdTe and CZT detector array structures which are 3 mm thick with 16×16 pixels and a 1 mm pixel pitch. These structures, in the two different implementations presented here, utilize either a small pixel effect or a drift phenomenon. An energy resolution of 4.75% at 122 keV has been obtained with a 30 ns peaking time using discrete electronics and a 57Co source. An output rate of 6×106 counts per second per individual pixel has been obtained with our ASIC readout electronics and a clinical CT X-ray tube. Additionally, the first clinical CT images, taken with several of our prototype photon-counting and energy

  13. Photon-Counting Multikilohertz Microlaser Altimeters for Airborne and Spaceborne Topographic Measurements

    Science.gov (United States)

    Degnan, John J.; Smith, David E. (Technical Monitor)

    2000-01-01

    We consider the optimum design of photon-counting microlaser altimeters operating from airborne and spaceborne platforms under both day and night conditions. Extremely compact Q-switched microlaser transmitters produce trains of low energy pulses at multi-kHz rates and can easily generate subnanosecond pulse-widths for precise ranging. To guide the design, we have modeled the solar noise background and developed simple algorithms, based on Post-Detection Poisson Filtering (PDPF), to optimally extract the weak altimeter signal from a high noise background during daytime operations. Practical technology issues, such as detector and/or receiver dead times, have also been considered in the analysis. We describe an airborne prototype, being developed under NASA's instrument Incubator Program, which is designed to operate at a 10 kHz rate from aircraft cruise altitudes up to 12 km with laser pulse energies on the order of a few microjoules. We also analyze a compact and power efficient system designed to operate from Mars orbit at an altitude of 300 km and sample the Martian surface at rates up to 4.3 kHz using a 1 watt laser transmitter and an 18 cm telescope. This yields a Power-Aperture Product of 0.24 W-square meter, corresponding to a value almost 4 times smaller than the Mars Orbiting Laser Altimeter (0. 88W-square meter), yet the sampling rate is roughly 400 times greater (4 kHz vs 10 Hz) Relative to conventional high power laser altimeters, advantages of photon-counting laser altimeters include: (1) a more efficient use of available laser photons providing up to two orders of magnitude greater surface sampling rates for a given laser power-telescope aperture product; (2) a simultaneous two order of magnitude reduction in the volume, cost and weight of the telescope system; (3) the unique ability to spatially resolve the source of the surface return in a photon counting mode through the use of pixellated or imaging detectors; and (4) improved vertical and

  14. Non-symmetric hybrids of noble metal-semiconductor: Interplay of nanoparticles and nanostructures in formation dynamics and plasmonic applications

    Directory of Open Access Journals (Sweden)

    Yinghui Sun

    2017-04-01

    Full Text Available Noble metal-semiconductor hybrids have been employed as fundamental structures in modern technologies. In these hybrids, their cooperative multiple functions attract much attention in recent years because of the interplay of nanoparticles and nanostructures. In this review, we summarize the interplay of nanoparticles and nanostructures in specific kinds of noble metal-semiconductor hybrids, termed as non-symmetric hybrids of noble metal-semiconductor. It particularly refers to metal nanoparticles (or semiconducting quantum dots at 1-dimensinal (1D and 2-dimensional (2D semiconductor (or metal nanostructures, in contrast to the core/shell and heterodimer nanostructures. First, we discuss the formation dynamics, especially in chemical growth and assembly as well as physical coating and deposition, of non-symmetric noble metal-semiconductor hybrids with nanoparticles on nanostructures. Second, we introduce the plasmon-related applications of these hybrids in heterogeneous catalysis, optoelectronic or photovoltaic devices, all-optical devices, and surface detection or modulation. This review not only provides a comprehensive understanding of the formation mechanisms of the non-symmetric metal-semiconductor hybrid nanostructures, but also may inspire new ideas of novel functional devices and applications based on these systems.

  15. Photon counting imaging and centroiding with an electron-bombarded CCD using single molecule localisation software

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M.; Barber, Matthew J.; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk

    2016-06-01

    Photon event centroiding in photon counting imaging and single-molecule localisation in super-resolution fluorescence microscopy share many traits. Although photon event centroiding has traditionally been performed with simple single-iteration algorithms, we recently reported that iterative fitting algorithms originally developed for single-molecule localisation fluorescence microscopy work very well when applied to centroiding photon events imaged with an MCP-intensified CMOS camera. Here, we have applied these algorithms for centroiding of photon events from an electron-bombarded CCD (EBCCD). We find that centroiding algorithms based on iterative fitting of the photon events yield excellent results and allow fitting of overlapping photon events, a feature not reported before and an important aspect to facilitate an increased count rate and shorter acquisition times.

  16. Mu-Spec - A High Performance Ultra-Compact Photon Counting spectrometer for Space Submillimeter Astronomy

    Science.gov (United States)

    Moseley, H.; Hsieh, W.-T.; Stevenson, T.; Wollack, E.; Brown, A.; Benford, D.; Sadleir; U-Yen, I.; Ehsan, N.; Zmuidzinas, J.; hide

    2011-01-01

    We have designed and are testing elements of a fully integrated submillimeter spectrometer based on superconducting microstrip technology. The instrument can offer resolving power R approximately 1500, and its high frequency cutoff is set by the gap of available high performance superconductors. All functions of the spectrometer are integrated - light is coupled to the microstrip circuit with a planar antenna, the spectra discrimination is achieved using a synthetic grating, orders are separated using planar filter, and detected using photon counting MKID detector. This spectrometer promises to revolutionize submillimeter spectroscopy from space. It replaces instruments with the scale of 1m with a spectrometer on a 10 cm Si wafer. The reduction in mass and volume promises a much higher performance system within available resource in a space mission. We will describe the system and the performance of the components that have been fabricated and tested.

  17. Development of Data Acquisition Methods for an FPGA-Based Photon Counting Detector

    Science.gov (United States)

    Ambily, S.; Sarpotdar, Mayuresh; Mathew, Joice; Sreejith, A. G.; Nirmal, K.; Prakash, Ajin; Safonova, Margarita; Murthy, Jayant

    MCP-based detectors are widely used in the ultraviolet (UV) region due to their low noise levels, high sensitivity and good spatial and temporal resolution. We have developed a compact near-UV (NUV) detector for high-altitude balloon and space flights, using off-the-shelf MCP, CMOS sensor, and optics. The detector is designed to be capable of working in the direct frame transfer mode as well in the photon counting mode for single photon event detection. The identification and centroiding of each photon event are done using an FPGA-based data acquisition and real-time processing system. In this paper, we discuss various algorithms and methods used in both operating modes, as well as their implementation on the hardware.

  18. Vision 20/20: Single photon counting x-ray detectors in medical imaging.

    Science.gov (United States)

    Taguchi, Katsuyuki; Iwanczyk, Jan S

    2013-10-01

    Photon counting detectors (PCDs) with energy discrimination capabilities have been developed for medical x-ray computed tomography (CT) and x-ray (XR) imaging. Using detection mechanisms that are completely different from the current energy integrating detectors and measuring the material information of the object to be imaged, these PCDs have the potential not only to improve the current CT and XR images, such as dose reduction, but also to open revolutionary novel applications such as molecular CT and XR imaging. The performance of PCDs is not flawless, however, and it seems extremely challenging to develop PCDs with close to ideal characteristics. In this paper, the authors offer our vision for the future of PCD-CT and PCD-XR with the review of the current status and the prediction of (1) detector technologies, (2) imaging technologies, (3) system technologies, and (4) potential clinical benefits with PCDs.

  19. Global analysis of time correlated single photon counting FRET-FLIM data.

    Science.gov (United States)

    Grecco, Hernan E; Roda-Navarro, Pedro; Verveer, Peter J

    2009-04-13

    Fluorescence lifetime imaging microscopy (FLIM) can be used to quantify molecular reactions in cells by detecting fluorescence resonance energy transfer (FRET). Confocal FLIM systems based on time correlated single photon counting (TCSPC) methods provide high spatial resolution and high sensitivity, but suffer from poor signal to noise ratios (SNR) that complicate quantitative analysis. We extend a global analysis method, originally developed for single frequency domain FLIM data, with a new filtering method optimized for FRET-FLIM data and apply it to TCSPC data. With this approach, the fluorescent lifetimes and relative concentrations of free and interacting molecules can be reliably estimated, even if the SNR is low. The required calibration values of the impulse response function are directly estimated from the data, eliminating the need for reference samples. The proposed method is efficient and robust, and can be routinely applied to analyze FRET-FLIM data acquired in intact cells.

  20. High energy X-ray photon counting imaging using linear accelerator and silicon strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Y., E-mail: cycjty@sophie.q.t.u-tokyo.ac.jp [Department of Bioengineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Shimazoe, K.; Yan, X. [Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Ueda, O.; Ishikura, T. [Fuji Electric Co., Ltd., Fuji, Hino, Tokyo 191-8502 (Japan); Fujiwara, T. [National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Uesaka, M.; Ohno, M. [Nuclear Professional School, the University of Tokyo, 2-22 Shirakata-shirane, Tokai, Ibaraki 319-1188 (Japan); Tomita, H. [Department of Quantum Engineering, Nagoya University, Furo, Chikusa, Nagoya 464-8603 (Japan); Yoshihara, Y. [Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Takahashi, H. [Department of Bioengineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2016-09-11

    A photon counting imaging detector system for high energy X-rays is developed for on-site non-destructive testing of thick objects. One-dimensional silicon strip (1 mm pitch) detectors are stacked to form a two-dimensional edge-on module. Each detector is connected to a 48-channel application specific integrated circuit (ASIC). The threshold-triggered events are recorded by a field programmable gate array based counter in each channel. The detector prototype is tested using 950 kV linear accelerator X-rays. The fast CR shaper (300 ns pulse width) of the ASIC makes it possible to deal with the high instant count rate during the 2 μs beam pulse. The preliminary imaging results of several metal and concrete samples are demonstrated.

  1. Continuously scanning time-correlated single-photon-counting single-pixel 3-D lidar

    Science.gov (United States)

    Henriksson, Markus; Larsson, Håkan; Grönwall, Christina; Tolt, Gustav

    2017-03-01

    Time-correlated single-photon-counting (TCSPC) lidar provides very high resolution range measurements. This makes the technology interesting for three-dimensional imaging of complex scenes with targets behind foliage or other obscurations. TCSPC is a statistical method that demands integration of multiple measurements toward the same area to resolve objects at different distances within the instantaneous field-of-view. Point-by-point scanning will demand significant overhead for the movement, increasing the measurement time. Here, the effect of continuously scanning the scene row-by-row is investigated and signal processing methods to transform this into low-noise point clouds are described. The methods are illustrated using measurements of a characterization target and an oak and hazel copse. Steps between different surfaces of less than 5 cm in range are resolved as two surfaces.

  2. Performance and capacity analysis of Poisson photon-counting based Iter-PIC OCDMA systems.

    Science.gov (United States)

    Li, Lingbin; Zhou, Xiaolin; Zhang, Rong; Zhang, Dingchen; Hanzo, Lajos

    2013-11-04

    In this paper, an iterative parallel interference cancellation (Iter-PIC) technique is developed for optical code-division multiple-access (OCDMA) systems relying on shot-noise limited Poisson photon-counting reception. The novel semi-analytical tool of extrinsic information transfer (EXIT) charts is used for analysing both the bit error rate (BER) performance as well as the channel capacity of these systems and the results are verified by Monte Carlo simulations. The proposed Iter-PIC OCDMA system is capable of achieving two orders of magnitude BER improvements and a 0.1 nats of capacity improvement over the conventional chip-level OCDMA systems at a coding rate of 1/10.

  3. Low-dose lung cancer screening with photon-counting CT: a feasibility study

    Science.gov (United States)

    Symons, Rolf; Cork, Tyler E.; Sahbaee, Pooyan; Fuld, Matthew K.; Kappler, Steffen; Folio, Les R.; Bluemke, David A.; Pourmorteza, Amir

    2017-01-01

    To evaluate the feasibility of using a whole-body photon-counting detector (PCD) CT scanner for low-dose lung cancer screening compared to a conventional energy integrating detector (EID) system. Radiation dose-matched EID and PCD scans of the COPDGene 2 phantom were acquired at different radiation dose levels (CTDIvol: 3.0, 1.5, and 0.75 mGy) and different tube voltages (120, 100, and 80 kVp). EID and PCD images were compared for quantitative Hounsfield unit (HU) accuracy, noise levels, and contrast-to-noise ratios (CNR) for detection of ground-glass nodules (GGN) and emphysema. The PCD HU accuracy was better than EID for water at all scan parameters. PCD HU stability for lung, GGN and emphysema regions were superior to EID and PCD attenuation values were more reproducible than EID for all scan parameters (all P  cancer screening while maintaining diagnostic quality.

  4. Characterization of spectrometric photon-counting X-ray detectors at different pitches

    Science.gov (United States)

    Jurdit, M.; Brambilla, A.; Moulin, V.; Ouvrier-Buffet, P.; Radisson, P.; Verger, L.

    2017-09-01

    There is growing interest in energy-sensitive photon-counting detectors based on high flux X-ray imaging. Their potential applications include medical imaging, non-destructive testing and security. Innovative detectors of this type will need to count individual photons and sort them into selected energy bins, at several million counts per second and per mm2. Cd(Zn)Te detector grade materials with a thickness of 1.5 to 3 mm and pitches from 800 μm down to 200 μm were assembled onto interposer boards. These devices were tested using in-house-developed full-digital fast readout electronics. The 16-channel demonstrators, with 256 energy bins, were experimentally characterized by determining spectral resolution, count rate, and charge sharing, which becomes challenging at low pitch. Charge sharing correction was found to efficiently correct X-ray spectra up to 40 × 106 incident photons.s-1.mm-2.

  5. Position and time sensitive photon counting detector with image charge delay-line readout

    Science.gov (United States)

    Czasch, Achim; Dangendorf, Volker; Milnes, James; Schössler, Sven; Lauck, Ronald; Spillmann, Uwe; Howorth, Jon; Jagutzki, Ottmar

    2007-09-01

    We have developed single photon counting image intensifier tubes combining position and time information read-out with at least 500x500 pixels and sub-nanosecond time resolution. This image intensifier type uses a resistive screen instead of a phosphor screen and the image charge pickup anode is placed outside the sealed tube. We present a novel delay-line anode design which allows for instance detecting simultaneously arriving pairs of photons. Due to the very low background this technique is suited for applications with very low light intensity and especially if a precise time tagging for each photon is required. We show results obtained with several anode types on a 25 mm image intensifier tube and a 40 mm open-face MCP detector and discuss the performance in neutron radiography, e.g. for homeland security, and the prospects for applications like Fluorescence Life-time Imaging Microscopy (FLIM), astronomy and X-ray polarimetry.

  6. Development and characterisation of a visible light photon counting imaging detector system

    CERN Document Server

    Barnstedt, J

    2002-01-01

    We report on the development of a visible light photon counting imaging detector system. The detector concept is based on standard 25 mm diameter microchannel plate image intensifiers made by Proxitronic in Bensheim (Germany). Modifications applied to these image intensifiers are the use of three microchannel plates instead of two and a high resistance ceramics plate used instead of the standard phosphor output screen. A wedge and strip anode mounted directly behind the high resistance ceramics plate was used as a read out device. This wedge and strip anode picks up the image charge of electron clouds emerging from the microchannel plates. The charge pulses are fed into four charge amplifiers and subsequently into a digital position decoding electronics, achieving a position resolution of up to 1024x1024 pixels. Mounting the anode outside the detector tube is a new approach and has the great advantage of avoiding electrical feedthroughs from the anode so that the standard image intensifier fabrication process...

  7. Linear Mode HgCdTe Avalanche Photodiodes for Photon Counting Applications

    Science.gov (United States)

    Sullivan, William, III; Beck, Jeffrey; Scritchfield, Richard; Skokan, Mark; Mitra, Pradip; Sun, Xiaoli; Abshire, James; Carpenter, Darren; Lane, Barry

    2015-01-01

    An overview of recent improvements in the understanding and maturity of linear mode photon counting with HgCdTe electron-initiated avalanche photodiodes is presented. The first HgCdTe LMPC 2x8 format array fabricated in 2011 with 64 micron pitch was a remarkable success in terms of demonstrating a high single photon signal to noise ratio of 13.7 with an excess noise factor of 1.3-1.4, a 7 ns minimum time between events, and a broad spectral response extending from 0.4 micron to 4.2 micron. The main limitations were a greater than 10x higher false event rate than expected of greater than 1 MHz, a 5-7x lower than expected APD gain, and a photon detection efficiency of only 50% when greater than 60% was expected. This paper discusses the reasons behind these limitations and the implementation of their mitigations with new results.

  8. Measurement of the light-field amplitude-correlation function through joint photon-count distributions.

    Science.gov (United States)

    Furcinitti, P.; Kuppenheimer, J. D.; Narducci, L. M.; Tuft , R. A.

    1972-01-01

    When an amplitude-stabilized He-Ne laser beam is scattered by a rotating ground glass with small surface inhomogeneities, the probability density of the instantaneous scattered-wave amplitude is Gaussian. In this paper, we suggest the use of the joint photon-count probability distribution to measure the absolute value of the electric-field amplitude-correlation function for random Gaussian light fields, and report the results of an experiment in which the Gaussian field is produced by scattering a light beam through a rotating ground glass. This procedure offers an alternative to other conventional methods, such as self-beating spectroscopy and irradiance-correlation techniques. The correlation time of the scattered-field amplitude in the present experiment has been measured with an accuracy of approximately 0.8%.

  9. A photon counting and a squeezing measurement method by the exact absorption and dispersion spectrum of Λ-type Atoms.

    Science.gov (United States)

    Naeimi, Ghasem; Alipour, Samira; Khademi, Siamak

    2016-01-01

    Recently, the master equations for the interaction of two-mode photons with a three-level Λ-type atom are exactly solved for the coherence terms. In this paper the exact absorption spectrum is applied for the presentation of a non-demolition photon counting method, for a few number of coupling photons, and its benefits are discussed. The exact scheme is also applied where the coupling photons are squeezed and the photon counting method is also developed for the measurement of the squeezing parameter of the coupling photons.

  10. Radiation-Resistant Photon-Counting Detector Package Providing Sub-ps Stability for Laser Time Transfer in Space

    Science.gov (United States)

    Prochzaka, Ivan; Kodat, Jan; Blazej, Josef; Sun, Xiaoli (Editor)

    2015-01-01

    We are reporting on a design, construction and performance of photon-counting detector packages based on silicon avalanche photodiodes. These photon-counting devices have been optimized for extremely high stability of their detection delay. The detectors have been designed for future applications in fundamental metrology and optical time transfer in space. The detectors have been qualified for operation in space missions. The exceptional radiation tolerance of the detection chip itself and of all critical components of a detector package has been verified in a series of experiments.

  11. A high-throughput, multi-channel photon-counting detector with picosecond timing

    Science.gov (United States)

    Lapington, J. S.; Fraser, G. W.; Miller, G. M.; Ashton, T. J. R.; Jarron, P.; Despeisse, M.; Powolny, F.; Howorth, J.; Milnes, J.

    2009-06-01

    High-throughput photon counting with high time resolution is a niche application area where vacuum tubes can still outperform solid-state devices. Applications in the life sciences utilizing time-resolved spectroscopies, particularly in the growing field of proteomics, will benefit greatly from performance enhancements in event timing and detector throughput. The HiContent project is a collaboration between the University of Leicester Space Research Centre, the Microelectronics Group at CERN, Photek Ltd., and end-users at the Gray Cancer Institute and the University of Manchester. The goal is to develop a detector system specifically designed for optical proteomics, capable of high content (multi-parametric) analysis at high throughput. The HiContent detector system is being developed to exploit this niche market. It combines multi-channel, high time resolution photon counting in a single miniaturized detector system with integrated electronics. The combination of enabling technologies; small pore microchannel plate devices with very high time resolution, and high-speed multi-channel ASIC electronics developed for the LHC at CERN, provides the necessary building blocks for a high-throughput detector system with up to 1024 parallel counting channels and 20 ps time resolution. We describe the detector and electronic design, discuss the current status of the HiContent project and present the results from a 64-channel prototype system. In the absence of an operational detector, we present measurements of the electronics performance using a pulse generator to simulate detector events. Event timing results from the NINO high-speed front-end ASIC captured using a fast digital oscilloscope are compared with data taken with the proposed electronic configuration which uses the multi-channel HPTDC timing ASIC.

  12. A dynamic attenuator improves spectral imaging with energy-discriminating, photon counting detectors.

    Science.gov (United States)

    Hsieh, Scott S; Pelc, Norbert J

    2015-03-01

    Energy-discriminating, photon counting (EDPC) detectors have high potential in spectral imaging applications but exhibit degraded performance when the incident count rate approaches or exceeds the characteristic count rate of the detector. In order to reduce the requirements on the detector, we explore the strategy of modulating the X-ray flux field using a recently proposed dynamic, piecewise-linear attenuator. A previous paper studied this modulation for photon counting detectors but did not explore the impact on spectral applications. In this work, we modeled detection with a bipolar triangular pulse shape (Taguchi et al., 2011) and estimated the Cramer-Rao lower bound (CRLB) of the variance of material selective and equivalent monoenergetic images, assuming deterministic errors at high flux could be corrected. We compared different materials for the dynamic attenuator and found that rare earth elements, such as erbium, outperformed previously proposed materials such as iron in spectral imaging. The redistribution of flux reduces the variance or dose, consistent with previous studies on benefits with conventional detectors. Numerical simulations based on DICOM datasets were used to assess the impact of the dynamic attenuator for detectors with several different characteristic count rates. The dynamic attenuator reduced the peak incident count rate by a factor of 4 in the thorax and 44 in the pelvis, and a 10 Mcps/mm (2) EDPC detector with dynamic attenuator provided generally superior image quality to a 100 Mcps/mm (2) detector with reference bowtie filter for the same dose. The improvement is more pronounced in the material images.

  13. Spectral response model for a multibin photon-counting spectral computed tomography detector and its applications.

    Science.gov (United States)

    Liu, Xuejin; Persson, Mats; Bornefalk, Hans; Karlsson, Staffan; Xu, Cheng; Danielsson, Mats; Huber, Ben

    2015-07-01

    Variations among detector channels in computed tomography can lead to ring artifacts in the reconstructed images and biased estimates in projection-based material decomposition. Typically, the ring artifacts are corrected by compensation methods based on flat fielding, where transmission measurements are required for a number of material-thickness combinations. Phantoms used in these methods can be rather complex and require an extensive number of transmission measurements. Moreover, material decomposition needs knowledge of the individual response of each detector channel to account for the detector inhomogeneities. For this purpose, we have developed a spectral response model that binwise predicts the response of a multibin photon-counting detector individually for each detector channel. The spectral response model is performed in two steps. The first step employs a forward model to predict the expected numbers of photon counts, taking into account parameters such as the incident x-ray spectrum, absorption efficiency, and energy response of the detector. The second step utilizes a limited number of transmission measurements with a set of flat slabs of two absorber materials to fine-tune the model predictions, resulting in a good correspondence with the physical measurements. To verify the response model, we apply the model in two cases. First, the model is used in combination with a compensation method which requires an extensive number of transmission measurements to determine the necessary parameters. Our spectral response model successfully replaces these measurements by simulations, saving a significant amount of measurement time. Second, the spectral response model is used as the basis of the maximum likelihood approach for projection-based material decomposition. The reconstructed basis images show a good separation between the calcium-like material and the contrast agents, iodine and gadolinium. The contrast agent concentrations are reconstructed with more

  14. An optimised method for material identification using a photon counting detector

    Energy Technology Data Exchange (ETDEWEB)

    Beldjoudi, Guillaume, E-mail: guillaume.beldjoudi@cea.fr [LETI MINATEC Campus, CEA Grenoble, 17, rue des Martyrs, 38054 Grenoble, Cedex 9 (France); Rebuffel, Veronique; Verger, Loieck [LETI MINATEC Campus, CEA Grenoble, 17, rue des Martyrs, 38054 Grenoble, Cedex 9 (France); Kaftandjian, Valerie [CNDRI - INSA Lyon, 20, Avenue Albert Einstein, 69621 Villeurbanne, Cedex (France); Rinkel, Jean [LETI MINATEC Campus, CEA Grenoble, 17, rue des Martyrs, 38054 Grenoble, Cedex 9 (France)

    2012-01-21

    X-ray photon counting detectors have become a competitive alternative to energy integrating systems in certain domains. However, processing methods currently used in radiography for investigating the composition of an object are an extension of dual energy methods and have started to show their limits with an increasing number of counting windows (bins). Thus, in a context of material recognition for homeland security, this study aims to introduce a new data processing method suitable for any type of detector, in integrating or counting mode, regardless of the number of bins. Additionally, a criterion to quantify the influence of the number of counting windows as well as the influence of their threshold position has been developed. The optimisation process is conducted in simulation by considering ideal detectors, and the results, for detectors with m=2, 3, 4 and 5 counting windows, are compared to those obtained with an analytical criterion developed in the literature and adapted to our study context. Both methods give identical results. In the final part, the performances of a spectrometric detector (energy windows width of 1 keV) and of optimised systems with m=2, 3, 4 and 5 bins are analysed for homogeneous plastic identification. The results show an increase in performance with increase in bin number until the performance level of the spectrometric detector is reached. Moreover, a discussion on the optimisation robustness as a function of material thickness to be identified is presented. The spectrometric detector, which does not require any optimisation of the bins thresholds, appears then to be a candidate of choice for material recognition when using X-ray photon counting detectors.

  15. Improved semiconductor lattice parameters and band gaps from a middle-range screened hybrid exchange functional.

    Science.gov (United States)

    Lucero, M J; Henderson, T M; Scuseria, G E

    2012-04-11

    We show that the middle-range exchange-correlation hybrid of Henderson, Izmaylov, Scuseria and Savin (HISS) performs extremely well for elemental and binary semiconductors with narrow or visible spectrum band gaps, as well as some wider gap or more ionic systems used in devices. The lattice parameters are superior to those predicted by the screened hybrid functional of Heyd, Scuseria and Ernzerhof (HSE), and provide a significant improvement over the geometries predicted by typical semilocal functionals, yielding results competitive with PBEsol, which was specially tuned for solids. HISS also yields band gaps superior to those produced by functionals developed specifically for the solid state. Timings indicate that HISS is more computationally efficient than HSE, implying that the high quality lattice constants coupled with improved optical band gap predictions render HISS a useful adjunct to HSE in the modeling of geometry-sensitive semiconductors.

  16. Nanoimprinted Hybrid Metal-Semiconductor Plasmonic Multilayers with Controlled Surface Nano Architecture for Applications in NIR Detectors

    OpenAIRE

    Khosroabadi, Akram A.; Gangopadhyay, Palash; Hernandez, Steven; Kim, Kyungjo; Peyghambarian, Nasser; Norwood, Robert A.

    2015-01-01

    We present a proof of concept for tunable plasmon resonance frequencies in a core shell nano-architectured hybrid metal-semiconductor multilayer structure, with Ag as the active shell and ITO as the dielectric modulation media. Our method relies on the collective change in the dielectric function within the metal semiconductor interface to control the surface. Here we report fabrication and optical spectroscopy studies of large-area, nanostructured, hybrid silver and indium tin oxide (ITO) st...

  17. To the theory of hybrid organics/semiconductor nanostructures in microcavity

    Science.gov (United States)

    Dubovskiy, O. A.; Agranovich, V. M.

    2017-02-01

    We consider the hybrid structure in microcavity where the energy of Frenkel exciton in organic layer is equal to the energy of Wannier - Mott exciton in semiconductor quantum well (QW). The exciton located in QW of semiconductor layer can interact with molecules of organic layer and under influence of this interaction can change the position jumping and exciting one of organic molecules. The exciton located in molecule of organic layer also can change the position jumping to semiconductor QW. The number of such jumps depends on the intensity of interaction. In the paper we consider the influence of direct Coulomb dipole-dipole interaction and indirect interaction through the optical field of microcavity on the kinetics of excitation. It was shown that the dispersion of hybrid states are modified by Coulomb interaction particularly when the distance between layers is enough small. The lowest branch of dispersion curves with deep minimum at nonzero wave vector may be useful in the studies of the condensation of low energy hybrid excitations.

  18. Modelling and simulation of pixelated photon counting X-ray detectors for imaging; Modellierung und Simulation physikalischer Eigenschaften photonenzaehlender Roentgenpixeldetektoren fuer die Bildgebung

    Energy Technology Data Exchange (ETDEWEB)

    Durst, Juergen

    2008-07-22

    First of all the physics processes generating the energy deposition in the sensor volume are investigated. The spatial resolution limits of photon interactions and the range of secondary electrons are discussed. The signatures in the energy deposition spectrum in pixelated detectors with direct conversion layers are described. The energy deposition for single events can be generated by the Monte-Carlo-Simulation package ROSI. The basic interactions of photons with matter are evaluated, resulting in the ability to use ROSI as a basis for the simulation of photon counting pixel detectors with direct conversion. In the context of this thesis a detector class is developed to simulate the response of hybrid photon counting pixel detectors using high-Z sensor materials like Cadmium Telluride (CdTe) or Gallium Arsenide (GaAs) in addition to silicon. To enable the realisation of such a simulation, the relevant physics processes and properties have to be implemented: processes in the sensor layer (provided by EGS4/LSCAT in ROSI), generation of charge carriers as electron hole pairs, diffusion and repulsion of charge carriers during drift and lifetime. Furthermore, several noise contributions of the electronics can be taken into account. The result is a detector class which allows the simulation of photon counting detectors. In this thesis the multiplicity framework is developed, including a formula to calculate or measure the zero frequency detective quantum efficiency (DQE). To enable the measurement of the multiplicity of detected events a cluster analysis program was developed. Random and systematic errors introduced by the cluster analysis are discussed. It is also shown that the cluster analysis method can be used to determine the averaged multiplicity with high accuracy. The method is applied to experimental data. As an example using the implemented detector class, the discriminator threshold dependency of the DQE and modulation transfer function is investigated in

  19. Hybrid polaritons in a resonant inorganic/organic semiconductor microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Höfner, M., E-mail: mhoefner@physik.hu-berlin.de; Sadofev, S.; Henneberger, F. [Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr.15, 12489 Berlin (Germany); Kobin, B.; Hecht, S. [Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin (Germany)

    2015-11-02

    We demonstrated the strong coupling regime in a hybrid inorganic-organic microcavity consisting of (Zn,Mg)O quantum wells and ladder-type oligo(p-phenylene) molecules embedded in a polymer matrix. A Fabry-Pérot cavity is formed by an epitaxially grown lower ZnMgO Bragg reflector and a dielectric mirror deposited atop of the organic layer. A clear anticrossing behavior of the polariton branches related to the Wannier-Mott and Frenkel excitons, and the cavity photon mode with a Rabi-splitting reaching 50 meV, is clearly identified by angular-dependent reflectivity measurements at low temperature. By tailoring the structural design, an equal mixing with weights of about 0.3 for all three resonances is achieved for the middle polariton branch at an incidence angle of about 35°.

  20. Hybrid artificial photosynthetic systems comprising semiconductors as light harvesters and biomimetic complexes as molecular cocatalysts.

    Science.gov (United States)

    Wen, Fuyu; Li, Can

    2013-11-19

    Solar fuel production through artificial photosynthesis may be a key to generating abundant and clean energy, thus addressing the high energy needs of the world's expanding population. As the crucial components of photosynthesis, the artificial photosynthetic system should be composed of a light harvester (e.g., semiconductor or molecular dye), a reduction cocatalyst (e.g., hydrogenase mimic, noble metal), and an oxidation cocatalyst (e.g., photosystem II mimic for oxygen evolution from water oxidation). Solar fuel production catalyzed by an artificial photosynthetic system starts from the absorption of sunlight by the light harvester, where charge separation takes place, followed by a charge transfer to the reduction and oxidation cocatalysts, where redox reaction processes occur. One of the most challenging problems is to develop an artificial photosynthetic solar fuel production system that is both highly efficient and stable. The assembly of cocatalysts on the semiconductor (light harvester) not only can facilitate the charge separation, but also can lower the activation energy or overpotential for the reactions. An efficient light harvester loaded with suitable reduction and oxidation cocatalysts is the key for high efficiency of artificial photosynthetic systems. In this Account, we describe our strategy of hybrid photocatalysts using semiconductors as light harvesters with biomimetic complexes as molecular cocatalysts to construct efficient and stable artificial photosynthetic systems. We chose semiconductor nanoparticles as light harvesters because of their broad spectral absorption and relatively robust properties compared with a natural photosynthesis system. Using biomimetic complexes as cocatalysts can significantly facilitate charge separation via fast charge transfer from the semiconductor to the molecular cocatalysts and also catalyze the chemical reactions of solar fuel production. The hybrid photocatalysts supply us with a platform to study the

  1. An x-ray-based capsule for colorectal cancer screening incorporating single photon counting technology

    Science.gov (United States)

    Lifshitz, Ronen; Kimchy, Yoav; Gelbard, Nir; Leibushor, Avi; Golan, Oleg; Elgali, Avner; Hassoon, Salah; Kaplan, Max; Smirnov, Michael; Shpigelman, Boaz; Bar-Ilan, Omer; Rubin, Daniel; Ovadia, Alex

    2017-03-01

    An ingestible capsule for colorectal cancer screening, based on ionizing-radiation imaging, has been developed and is in advanced stages of system stabilization and clinical evaluation. The imaging principle allows future patients using this technology to avoid bowel cleansing, and to continue the normal life routine during procedure. The Check-Cap capsule, or C-Scan ® Cap, imaging principle is essentially based on reconstructing scattered radiation, while both radiation source and radiation detectors reside within the capsule. The radiation source is a custom-made radioisotope encased in a small canister, collimated into rotating beams. While traveling along the human colon, irradiation occurs from within the capsule towards the colon wall. Scattering of radiation occurs both inside and outside the colon segment; some of this radiation is scattered back and detected by sensors onboard the capsule. During procedure, the patient receives small amounts of contrast agent as an addition to his/her normal diet. The presence of contrast agent inside the colon dictates the dominant physical processes to become Compton Scattering and X-Ray Fluorescence (XRF), which differ mainly by the energy of scattered photons. The detector readout electronics incorporates low-noise Single Photon Counting channels, allowing separation between the products of these different physical processes. Separating between radiation energies essentially allows estimation of the distance from the capsule to the colon wall, hence structural imaging of the intraluminal surface. This allows imaging of structural protrusions into the colon volume, especially focusing on adenomas that may develop into colorectal cancer.

  2. Theoretical characterization of performance effectiveness of photon-counting technique for digital radiography applications

    Science.gov (United States)

    Yun, Seungman; Kim, Jaehyuk; Huh, Yoonsuk; Kim, Jungha; Park, Sujin; Kim, Jungmin; Kim, Jongpil; Yoon, Kyung Hun; Jo, JaeMoon

    2017-03-01

    Photon-counting (PC) technique has been paid attention to digital radiography applications due to its potential in lowdose operation and multi-energy imaging capability. In this study, we theoretically investigate the performance gain in digital radiography when the PC detectors are used instead of the conventional energy-integrating (EI) detectors. We use the Monte Carlo technique for estimating energy-absorption distributions in detector materials such as CdTe for the PC detector and CsI for the EI detector. To estimate the signal and noise transfers through the two different detectoroperation schemes, we use the cascaded linear-systems approach. In the Monte Carlo simulations, the square and rectangle focal spots are considered to mimic the advanced carbon nanotube (CNT) and conventional filament cathodes, respectively. From the simulation results, the modulation-transfer functions of the PC detector are more sensitive to asymmetric focal spot geometry than those of the EI detector. On the other hand, the PC detector shows better image signal-to-noise ratio than the EI detector; hence better dose efficiency with the PC detector. The dose efficiency of the PC detector in comparison with the EI detector is however marginal for the filament x-ray beam whereas the dose efficiency is not negligible for the CNT x-ray beam. The theoretical upper limits of the imaging performance of the advanced digital radiography technology are reported in this study.

  3. Estimation of signal and noise for a whole-body photon counting research CT system.

    Science.gov (United States)

    Li, Zhoubo; Leng, Shuai; Yu, Zhicong; Kappler, Stephen; McCollough, Cynthia H

    2016-02-01

    Photon-counting CT (PCCT) may yield potential value for many clinical applications due to its relative immunity to electronic noise, increased geometric efficiency relative to current scintillating detectors, and the ability to resolve energy information about the detected photons. However, there are a large number of parameters that require optimization, particularly the energy thresholds configurations. Fast and accurate estimation of signal and noise in PCCT can benefit the optimization of acquisition parameters for specific diagnostic tasks. Based on the acquisition parameters and detector response of our research PCCT system, we derived mathematical models for both signal and noise. The signal model took the tube spectrum, beam filtration, object attenuation, water beam hardening, and detector response into account. The noise model considered the relationship between noise and radiation dose, as well as the propagation of noise as threshold data are subtracted to yield energy bin data. To determine the absolute noise value, a noise look-up table (LUT) was acquired using a limited number of calibration scans. The noise estimation algorithm then used the noise LUT to estimate noise for scans with a variety of combination of energy thresholds, dose levels, and object attenuation. Validation of the estimation algorithms was performed on our whole-body research PCCT system using semi-anthropomorphic water phantoms and solutions of calcium and iodine. The algorithms achieved accurate estimation of signal and noise for a variety of scanning parameter combinations. The proposed method can be used to optimize energy thresholds configuration for many clinical applications of PCCT.

  4. Simultaneous imaging of multiple focal planes in scanning two-photon absorption microscope by photon counting

    Science.gov (United States)

    Carriles, Ramón; Hoover, Erich E.; Amir, Wafa; Squier, Jeffery A.

    2007-09-01

    We demonstrate a two-photon absorption scanning microscope capable of imaging two focal planes simultaneously. The 23MHz fundamental laser is split in two, one part delayed in time while the other is focused with a deformable mirror to change its divergence. Both parts are then recombined to form a 46MHz pulse train consisting of two interlaced trains with different divergences that after the objective are focused at different sample depths. At the detection path, photon counting techniques allow photons coming from each depth to be separated based on their relative timing with respect to the 46MHz train. The separation is accomplished using a field-programmable gate array that has been programmed to switch back and forth between two counters at a rate provided by a master clock generated by the 46MHz pulse train. The computer that controls the scanners reads and resets the counters before moving to a new pixel. The scheme is demonstrated for two depths but can be extended to a larger number, the ultimate limit being the fluorescence lifetime. This technique could also be implemented for second or third harmonic generation microscopy, in this case the ultimate achievable number of focal planes would be determined by the electronics speed.

  5. Si-strip photon counting detectors for contrast-enhanced spectral mammography

    Science.gov (United States)

    Chen, Buxin; Reiser, Ingrid; Wessel, Jan C.; Malakhov, Nail; Wawrzyniak, Gregor; Hartsough, Neal E.; Gandhi, Thulasi; Chen, Chin-Tu; Iwanczyk, Jan S.; Barber, William C.

    2015-08-01

    We report on the development of silicon strip detectors for energy-resolved clinical mammography. Typically, X-ray integrating detectors based on scintillating cesium iodide CsI(Tl) or amorphous selenium (a-Se) are used in most commercial systems. Recently, mammography instrumentation has been introduced based on photon counting Si strip detectors. The required performance for mammography in terms of the output count rate, spatial resolution, and dynamic range must be obtained with sufficient field of view for the application, thus requiring the tiling of pixel arrays and particular scanning techniques. Room temperature Si strip detector, operating as direct conversion x-ray sensors, can provide the required speed when connected to application specific integrated circuits (ASICs) operating at fast peaking times with multiple fixed thresholds per pixel, provided that the sensors are designed for rapid signal formation across the X-ray energy ranges of the application. We present our methods and results from the optimization of Si-strip detectors for contrast enhanced spectral mammography. We describe the method being developed for quantifying iodine contrast using the energy-resolved detector with fixed thresholds. We demonstrate the feasibility of the method by scanning an iodine phantom with clinically relevant contrast levels.

  6. 32-channel time-correlated-single-photon-counting system for high-throughput lifetime imaging

    Science.gov (United States)

    Peronio, P.; Labanca, I.; Acconcia, G.; Ruggeri, A.; Lavdas, A. A.; Hicks, A. A.; Pramstaller, P. P.; Ghioni, M.; Rech, I.

    2017-08-01

    Time-Correlated Single Photon Counting (TCSPC) is a very efficient technique for measuring weak and fast optical signals, but it is mainly limited by the relatively "long" measurement time. Multichannel systems have been developed in recent years aiming to overcome this limitation by managing several detectors or TCSPC devices in parallel. Nevertheless, if we look at state-of-the-art systems, there is still a strong trade-off between the parallelism level and performance: the higher the number of channels, the poorer the performance. In 2013, we presented a complete and compact 32 × 1 TCSPC system, composed of an array of 32 single-photon avalanche diodes connected to 32 time-to-amplitude converters, which showed that it was possible to overcome the existing trade-off. In this paper, we present an evolution of the previous work that is conceived for high-throughput fluorescence lifetime imaging microscopy. This application can be addressed by the new system thanks to a centralized logic, fast data management and an interface to a microscope. The new conceived hardware structure is presented, as well as the firmware developed to manage the operation of the module. Finally, preliminary results, obtained from the practical application of the technology, are shown to validate the developed system.

  7. Development of a high-performance multichannel system for time-correlated single photon counting

    Science.gov (United States)

    Peronio, P.; Cominelli, A.; Acconcia, G.; Rech, I.; Ghioni, M.

    2017-05-01

    Time-Correlated Single Photon Counting (TCSPC) is one of the most effective techniques for measuring weak and fast optical signals. It outperforms traditional "analog" techniques due to its high sensitivity along with high temporal resolution. Despite those significant advantages, a main drawback still exists, which is related to the long acquisition time needed to perform a measurement. In past years many TCSPC systems have been developed with higher and higher number of channels, aimed to dealing with that limitation. Nevertheless, modern systems suffer from a strong trade-off between parallelism level and performance: the higher the number of channels the poorer the performance. In this work we present the design of a 32x32 TCSPC system meant for overtaking the existing trade-off. To this aim different technologies has been employed, to get the best performance both from detectors and sensing circuits. The exploitation of different technologies will be enabled by Through Silicon Vias (TSVs) which will be investigated as a possible solution for connecting the detectors to the sensing circuits. When dealing with a high number of channels, the count rate is inevitably set by the affordable throughput to the external PC. We targeted a throughput of 10Gb/s, which is beyond the state of the art, and designed the number of TCSPC channels accordingly. A dynamic-routing logic will connect the detectors to the lower number of acquisition chains.

  8. pawFLIM: reducing bias and uncertainty to enable lower photon count in FLIM experiments

    Science.gov (United States)

    Silberberg, Mauro; Grecco, Hernán E.

    2017-06-01

    Förster resonant energy transfer measured by fluorescence lifetime imaging microscopy (FRET-FLIM) is the method of choice for monitoring the spatio-temporal dynamics of protein interactions in living cells. To obtain an accurate estimate of the molecular fraction of interacting proteins requires a large number of photons, which usually precludes the observation of a fast process, particularly with time correlated single photon counting (TCSPC) based FLIM. In this work, we propose a novel method named pawFLIM (phasor analysis via wavelets) that allows the denoising of FLIM datasets by adaptively and selectively adjusting the desired compromise between spatial and molecular resolution. The method operates by applying a weighted translational-invariant Haar-wavelet transform denoising algorithm to phasor images. This results in significantly less bias and mean square error than other existing methods. We also present a new lifetime estimator (named normal lifetime) with a smaller mean squared error and overall bias as compared to frequency domain phase and modulation lifetimes. Overall, we present an approach that will enable the observation of the dynamics of biological processes at the molecular level with better temporal and spatial resolution.

  9. The LAMBDA photon-counting pixel detector and high-Z sensor development

    Science.gov (United States)

    Pennicard, D.; Smoljanin, S.; Struth, B.; Hirsemann, H.; Fauler, A.; Fiederle, M.; Tolbanov, O.; Zarubin, A.; Tyazhev, A.; Shelkov, G.; Graafsma, H.

    2014-12-01

    Many X-ray experiments at third-generation synchrotrons benefit from using single-photon-counting detectors, due to their high signal-to-noise ratio and potential for high-speed measurements. LAMBDA (Large Area Medipix3-Based Detector Array) is a pixel detector system based on the Medipix3 readout chip. It combines the features of Medipix3, such as a small pixel size of 55 μm and flexible functionality, with a large tileable module design consisting of 12 chips (1536 × 512 pixels) and a high-speed readout system capable of running at 2000 frames per second. To enable high-speed experiments with hard X-rays, the LAMBDA system has been combined with different high-Z sensor materials. Room-temperature systems using GaAs and CdTe systems have been produced and tested with X-ray tubes and at synchrotron beamlines. Both detector materials show nonuniformities in their raw image response, but the pixel yield is high and the uniformity can be improved by flat-field correction, particularly in the case of GaAs. High-frame-rate experiments show that useful information can be gained on millisecond timescales in synchrotron experiments with these sensors.

  10. ERICA: an energy resolving photon counting readout ASIC for X-ray in-line cameras

    Science.gov (United States)

    Macias-Montero, J.-G.; Sarraj, M.; Chmeissani, M.; Moore, T.; Casanova, R.; Martinez, R.; Puigdengoles, C.; Prats, X.; Kolstein, M.

    2016-12-01

    We present ERICA (Energy Resolving Inline X-ray Camera) a photon-counting readout ASIC, with 6 energy bins. The ASIC is composed of a matrix of 8 × 20 pixels controlled by a global digital controller and biased with 7 independent digital to analog converters (DACs) and a band-gap current reference. The pixel analog front-end includes a charge sensitive amplifier with 16 mV/ke- gain and dynamic range of 45 ke-. ERICA has programmable pulse width, an adjustable constant current feedback resistor, a linear test pulse generator, and six discriminators with 6-bit local threshold adjustment. The pixel digital back-end includes the digital controller, 8 counters of 8-bit depth, half-full buffer flag for any of the 8 counters, a 74-bit shadow/shift register, a 74-bit configuration latch, and charge sharing compensation processing to perform the energy classification and counting operations of every detected photon in 1 μ s. The pixel size is 330 μm × 330 μm and its average consumption is 150 μW. Implemented in TSMC 0.25 μm CMOS process, the ASIC pixel's equivalent noise charge (ENC) is 90 e- RMS connected to a 1 mm thickness matching CdTe detector biased at -300 V with a total leakage current of 20 nA.

  11. Energy-sensitive photon counting detector-based X-ray computed tomography.

    Science.gov (United States)

    Taguchi, Katsuyuki

    2017-03-01

    Energy-sensitive photon counting detectors (PCDs) have recently been developed for medical X-ray computed tomography (CT) imaging and a handful of prototype PCD-CT systems have been built and evaluated. PCDs detect X-rays by using mechanisms that are completely different from the current CT detectors (i.e., energy integrating detectors or EIDs); PCDs count photons and obtain the information of the object tissues (i.e., the effective atomic numbers and mass densities) to be imaged. Therefore, these PCDs have the potential not only for evolution-to improve the current CT images such as providing dose reduction-but also for a revolution-to enable novel applications with a new concept such as molecular CT imaging. The performance of PCDs, however, is not flawless, and thus, it requires integrated efforts to develop PCD-CT for clinical use. In this article, we review the current status and the prediction for the future of PCDs, PCD-CT systems, and potential clinical applications.

  12. Characterisation of a single photon counting pixel system for imaging of low-contrast objects

    CERN Document Server

    Mikulec, B; Dipasquale, G; Schwarz, C; Watt, J

    2001-01-01

    In the framework of the Medipix collaboration the PCC, a single photon counting pixel chip, has been developed with the aim of improving the contrast resolution in medical imaging applications. The PCC consists of a matrix of 64x64 square pixels with 170 mm side length, each pixel comprising a 15 bit counter and a pulse height discriminator. The chip has been bump bonded to equally segmented 200 mm thick SI-LEC GaAs detectors showing a very high absorption energy for X-rays used in diagnostics. An absolute calibration of the system with a radioactive source and a synchrotron beam are described resulting in the value of the test input capacitance of ~24.7 fF. Using this value a full characterisation of the system from electrical measurements is presented. The entire system can reach a minimum threshold of ~2100 e- with ~250e- rms noise. One of the characteristics of the PCC is the possibility to adjust the thresholds of all pixels on a pixel-by-pixel basis with 3-bit precision. The threshold distribution after...

  13. A position- and time-sensitive photon-counting detector with delay- line read-out

    Science.gov (United States)

    Jagutzki, Ottmar; Dangendorf, Volker; Lauck, Ronald; Czasch, Achim; Milnes, James

    2007-05-01

    We have developed image intensifier tubes with delay-anode read-out for time- and position-sensitive photon counting. The timing precision is better than 1 ns with 1000x1000 pixels position resolution and up to one megacounts/s processing rate. Large format detectors of 40 and 75 mm active diameter with internal helical-wire delay-line anodes have been produced and specified. A different type of 40 and 25 mm tubes with semi-conducting screen for image charge read-out allow for an economic and robust tube design and for placing the read-out anodes outside the sealed housing. Two types of external delay-line anodes, i.e. pick-up electrodes for the image charge, have been tested. We present tests of the detector and anode performance. Due to the low background this technique is well suited for applications with very low light intensity and especially if a precise time tagging for each photon is required. As an example we present the application of scintillator read-out in time-of-flight (TOF) neutron radiography. Further applications so far are Fluorescence Life-time Microscopy (FLIM) and Astronomy.

  14. On the performance of bioanalytical fluorescence correlation spectroscopy measurements in a multiparameter photon-counting microscope

    Energy Technology Data Exchange (ETDEWEB)

    Mazouchi, Amir; Liu Baoxu; Bahram, Abdullah [Department of Physics, Institute for Optical Sciences, University of Toronto, Toronto (Canada); Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6 (Canada); Gradinaru, Claudiu C., E-mail: claudiu.gradinaru@utoronto.ca [Department of Physics, Institute for Optical Sciences, University of Toronto, Toronto (Canada); Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6 (Canada)

    2011-02-28

    Fluorescence correlation spectroscopy (FCS) data acquisition and analysis routines were developed and implemented in a home-built, multiparameter photon-counting microscope. Laser excitation conditions were investigated for two representative fluorescent probes, Rhodamine110 and enhanced green fluorescent protein (EGFP). Reliable local concentrations and diffusion constants were obtained by fitting measured FCS curves, provided that the excitation intensity did not exceed 20% of the saturation level for each fluorophore. Accurate results were obtained from FCS measurements for sample concentrations varying from pM to {mu}M range, as well as for conditions of high background signals. These experimental constraints were found to be determined by characteristics of the detection system and by the saturation behavior of the fluorescent probes. These factors actually limit the average number of photons that can be collected from a single fluorophore passing through the detection volume. The versatility of our setup and the data analysis capabilities were tested by measuring the mobility of EGFP in the nucleus of Drosophila cells under conditions of high concentration and molecular crowding. As a bioanalytical application, we studied by FCS the binding affinity of a novel peptide-based drug to the cancer-regulating STAT3 protein and corroborated the results with fluorescence polarization analysis derived from the same photon data.

  15. Note: Space qualified photon counting detector for laser time transfer with picosecond precision and stability.

    Science.gov (United States)

    Prochazka, Ivan; Kodet, Jan; Blazej, Josef

    2016-05-01

    The laser time transfer link is under construction for the European Space Agency in the frame of Atomic Clock Ensemble in Space. We have developed and tested the flying unit of the photon counting detector optimized for this space mission. The results are summarized in this Note. An extreme challenge was to build a detector package, which is rugged, small and which provides long term detection delay stability on picosecond level. The device passed successfully all the tests required for space missions on the low Earth orbits. The detector is extremely rugged and compact. Its long term detection delay stability is excellent, it is better than ±1 ps/day, in a sense of time deviation it is better than 0.5 ps for averaging times of 2000 s to several hours. The device is capable to operate in a temperature range of -55 °C up to +60 °C, the change of the detection delay with temperature is +0.5 ps/K. The device is ready for integration into the space structure now.

  16. Approaching the Ultimate Limits of Communication Efficiency with a Photon-Counting Detector

    Science.gov (United States)

    Erkmen, Baris; Moision, Bruce; Dolinar, Samuel J.; Birnbaum, Kevin M.; Divsalar, Dariush

    2012-01-01

    Coherent states achieve the Holevo capacity of a pure-loss channel when paired with an optimal measurement, but a physical realization of this measurement is as of yet unknown, and it is also likely to be of high complexity. In this paper, we focus on the photon-counting measurement and study the photon and dimensional efficiencies attainable with modulations over classical- and nonclassical-state alphabets. We first review the state-of-the-art coherent on-off-keying (OOK) with a photoncounting measurement, illustrating its asymptotic inefficiency relative to the Holevo limit. We show that a commonly made Poisson approximation in thermal noise leads to unbounded photon information efficiencies, violating the conjectured Holevo limit. We analyze two binary-modulation architectures that improve upon the dimensional versus photon efficiency tradeoff achievable with conventional OOK. We show that at high photon efficiency these architectures achieve an efficiency tradeoff that differs from the best possible tradeoff--determined by the Holevo capacity--by only a constant factor. The first architecture we analyze is a coherent-state transmitter that relies on feedback from the receiver to control the transmitted energy. The second architecture uses a single-photon number-state source.

  17. K-edge energy-based calibration method for photon counting detectors

    Science.gov (United States)

    Ge, Yongshuai; Ji, Xu; Zhang, Ran; Li, Ke; Chen, Guang-Hong

    2018-01-01

    In recent years, potential applications of energy-resolved photon counting detectors (PCDs) in the x-ray medical imaging field have been actively investigated. Unlike conventional x-ray energy integration detectors, PCDs count the number of incident x-ray photons within certain energy windows. For PCDs, the interactions between x-ray photons and photoconductor generate electronic voltage pulse signals. The pulse height of each signal is proportional to the energy of the incident photons. By comparing the pulse height with the preset energy threshold values, x-ray photons with specific energies are recorded and sorted into different energy bins. To quantitatively understand the meaning of the energy threshold values, and thus to assign an absolute energy value to each energy bin, energy calibration is needed to establish the quantitative relationship between the threshold values and the corresponding effective photon energies. In practice, the energy calibration is not always easy, due to the lack of well-calibrated energy references for the working energy range of the PCDs. In this paper, a new method was developed to use the precise knowledge of the characteristic K-edge energy of materials to perform energy calibration. The proposed method was demonstrated using experimental data acquired from three K-edge materials (viz., iodine, gadolinium, and gold) on two different PCDs (Hydra and Flite, XCounter, Sweden). Finally, the proposed energy calibration method was further validated using a radioactive isotope (Am-241) with a known decay energy spectrum.

  18. On Approaching the Ultimate Limits of Communication Using a Photon-Counting Detector

    Science.gov (United States)

    Erkmen, Baris I.; Moision, Bruce E.; Dolinar, Samuel J.; Birnbaum, Kevin M.; Divsalar, Dariush

    2012-01-01

    Coherent states achieve the Holevo capacity of a pure-loss channel when paired with an optimal measurement, but a physical realization of this measurement scheme is as of yet unknown, and it is also likely to be of high complexity. In this paper, we focus on the photon-counting measurement and study the photon and dimensional efficiencies attainable with modulations over classical- and nonclassical-state alphabets. We analyze two binary modulation architectures that improve upon the dimensional versus photon efficiency tradeoff achievable with the state-of-the-art coherent-state on-off keying modulation. We show that at high photon efficiency these architectures achieve an efficiency tradeoff that differs from the best possible tradeoff--determined by the Holevo capacity--by only a constant factor. The first architecture we analyze is a coherent-state transmitter that relies on feedback from the receiver to control the transmitted energy. The second architecture uses a single-photon number-state source.

  19. Spectral CT of the extremities with a silicon strip photon counting detector

    Science.gov (United States)

    Sisniega, A.; Zbijewski, W.; Stayman, J. W.; Xu, J.; Taguchi, K.; Siewerdsen, J. H.

    2015-03-01

    Purpose: Photon counting x-ray detectors (PCXDs) are an important emerging technology for spectral imaging and material differentiation with numerous potential applications in diagnostic imaging. We report development of a Si-strip PCXD system originally developed for mammography with potential application to spectral CT of musculoskeletal extremities, including challenges associated with sparse sampling, spectral calibration, and optimization for higher energy x-ray beams. Methods: A bench-top CT system was developed incorporating a Si-strip PCXD, fixed anode x-ray source, and rotational and translational motions to execute complex acquisition trajectories. Trajectories involving rotation and translation combined with iterative reconstruction were investigated, including single and multiple axial scans and longitudinal helical scans. The system was calibrated to provide accurate spectral separation in dual-energy three-material decomposition of soft-tissue, bone, and iodine. Image quality and decomposition accuracy were assessed in experiments using a phantom with pairs of bone and iodine inserts (3, 5, 15 and 20 mm) and an anthropomorphic wrist. Results: The designed trajectories improved the sampling distribution from 56% minimum sampling of voxels to 75%. Use of iterative reconstruction (viz., penalized likelihood with edge preserving regularization) in combination with such trajectories resulted in a very low level of artifacts in images of the wrist. For large bone or iodine inserts (>5 mm diameter), the error in the estimated material concentration was decomposition in joint imaging proved feasible through a combination of rotation-translation acquisition trajectories and iterative reconstruction with optimized regularization.

  20. Investigation of organic semiconductor interlayers in hybrid PEDOT:PSS/silicon solar cells

    Science.gov (United States)

    Weingarten, Martin; Zweipfennig, Thorsten; Sanders, Simon; Stümmler, Dominik; Pfeiffer, Pascal; Vescan, Andrei; Kalisch, Holger

    2016-10-01

    In the last years, hybrid organic/inorganic solar cells have attracted great interest in photovoltaic research due to their expected potential to combine the advantages of both material classes, the excellent electrical properties and stability of the inorganic and the low-cost processability of the organic semiconductors. This work is focused on hybrid solar cells based on n-doped crystalline Si as the inorganic and the polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) as the organic part of the device. The hole-conducting organic semiconductors poly(3-hexylthiophene-2,5-diyl) (P3HT) and 2,2‧,7,7‧-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9‧-spirobifluorene (Spiro-MeOTAD) are investigated as electron blocking interlayers to reduce the parasitic electron current into the metal top contact and thereby increase the efficiency of the solar cell. In this context, P3HT is identified to be insufficient as an interlayer material due to unfavorable hysteresis effects. On the other hand, for solar cells with a Spiro-MeOTAD interlayer, the power conversion efficiency (PCE) is significantly increased. This is mainly attributed to an increased short-circuit current density. For the best performing device, a PCE of 14.3% is achieved, which is one of the highest values reported for this type of hybrid solar cells so far.

  1. FABRICATION AND UTILIZATION OF ZINC OXIDE NANOFIBRES FOR SEMICONDUCTORS OF PHOTOVOLTAICAND PIEZOELECTRIC-BASED HYBRID GENERATORS

    Directory of Open Access Journals (Sweden)

    SUYITNO

    2017-12-01

    Full Text Available The objective of this study is to develop and test hybrid generators harvesting both solar and mechanical energy. The hybrid generators work using photovoltaic- and piezoelectric-principles, where the active semiconductors were ZnO nanofibres synthesized by electrospinning at various feed rates of precursor. The results show that the crystallinity, crystalline size, fibre size, and fibre uniformity examined by X-ray diffraction and scanning electron microscopy were strongly affected by changing the solution flow rate among 2, 4, 6, and 8 μL/min. Meanwhile, the voltage and power generated from the hybrid generators were influenced by the crystalline quality and morphology of the ZnO fibres. The highest voltages of photovoltaic- and piezoelectric-based hybrid generators were 507 and 36.3 mV, respectively. In addition, the maximum power values of photovoltaic- and piezoelectric-based generators were 706.72 μW/cm² and 49.6 nW/cm², respectively. Therefore, hybrid generators are of interest for fabrication into self-power devices.

  2. Tightly bound indirect exciton in single-layer hybrid organic-inorganic perovskite semiconductor

    Science.gov (United States)

    Li, Jing; Liu, Tao; Liew, Timothy C. H.

    2017-10-01

    We theoretically study the direct and indirect excitons (IXs) in a single-layer hybrid organic-inorganic perovskite (HOIP) semiconductor. Due to the 2D nature, the single-layer HOIP supports the large binding energy of IXs and direct excitons over a wide range of applied electric fields, which exceed the thermal energy of room temperature. Moreover, the ground-state IX has a lower energy than that of direct exciton, which will extend the coherence and relaxation time of IXs. This is beneficial to optoelectronic applications and excitonic information processing devices of IXs.

  3. TU-EF-207-02: Spectral Mammography Based on Photon Counting Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Molloi, S. [University of California (United States)

    2015-06-15

    Breast imaging technology is advancing on several fronts. In digital mammography, the major technological trend has been on optimization of approaches for performing combined mammography and tomosynthesis using the same system. In parallel, photon-counting slot-scan mammography is now in clinical use and more efforts are directed towards further development of this approach for spectral imaging. Spectral imaging refers to simultaneous acquisition of two or more energy-windowed images. Depending on the detector and associated electronics, there are a number of ways this can be accomplished. Spectral mammography using photon-counting detectors can suppress electronic noise and importantly, it enables decomposition of the image into various material compositions of interest facilitating quantitative imaging. Spectral imaging can be particularly important in intravenously injected contrast mammography and eventually tomosynthesis. The various approaches and applications of spectral mammography are discussed. Digital breast tomosynthesis relies on the mechanical movement of the x-ray tube to acquire a number of projections in a predefined arc, typically from 9 to 25 projections over a scan angle of +/−7.5 to 25 degrees depending on the particular system. The mechanical x-ray tube motion requires relatively long acquisition time, typically between 3.7 to 25 seconds depending on the system. Moreover, mechanical scanning may have an effect on the spatial resolution due to internal x-ray filament or external mechanical vibrations. New x-ray source arrays have been developed and they are aimed at replacing the scanned x-ray tube for improved acquisition time and potentially for higher spatial resolution. The potential advantages and challenges of this approach are described. Combination of digital mammography and tomosynthesis in a single system places increased demands on certain functional aspects of the detector and overall performance, particularly in the tomosynthesis

  4. A unified statistical framework for material decomposition using multienergy photon counting x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jiyoung; Kang, Dong-Goo; Kang, Sunghoon; Sung, Younghun [Samsung Advanced Institute of Technology (SAIT), San 14, Nong-seo dong, Giheung-gu, Yongin, Kyunggi 446-712 (Korea, Republic of); Ye, Jong Chul [Bio-Imaging and Signal Processing Laboratory, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejon 305-701 (Korea, Republic of)

    2013-09-15

    Purpose: Material decomposition using multienergy photon counting x-ray detectors (PCXD) has been an active research area over the past few years. Even with some success, the problem of optimal energy selection and three material decomposition including malignant tissue is still on going research topic, and more systematic studies are required. This paper aims to address this in a unified statistical framework in a mammographic environment.Methods: A unified statistical framework for energy level optimization and decomposition of three materials is proposed. In particular, an energy level optimization algorithm is derived using the theory of the minimum variance unbiased estimator, and an iterative algorithm is proposed for material composition as well as system parameter estimation under the unified statistical estimation framework. To verify the performance of the proposed algorithm, the authors performed simulation studies as well as real experiments using physical breast phantom and ex vivo breast specimen. Quantitative comparisons using various performance measures were conducted, and qualitative performance evaluations for ex vivo breast specimen were also performed by comparing the ground-truth malignant tissue areas identified by radiologists.Results: Both simulation and real experiments confirmed that the optimized energy bins by the proposed method allow better material decomposition quality. Moreover, for the specimen thickness estimation errors up to 2 mm, the proposed method provides good reconstruction results in both simulation and real ex vivo breast phantom experiments compared to existing methods.Conclusions: The proposed statistical framework of PCXD has been successfully applied for the energy optimization and decomposition of three material in a mammographic environment. Experimental results using the physical breast phantom and ex vivo specimen support the practicality of the proposed algorithm.

  5. Depth imaging in highly scattering underwater environments using time-correlated single-photon counting

    Science.gov (United States)

    Maccarone, Aurora; McCarthy, Aongus; Halimi, Abderrahim; Tobin, Rachael; Wallace, Andy M.; Petillot, Yvan; McLaughlin, Steve; Buller, Gerald S.

    2016-10-01

    This paper presents an optical depth imaging system optimized for highly scattering environments such as underwater. The system is based on the time-correlated single-photon counting (TCSPC) technique and the time-of-flight approach. Laboratory-based measurements demonstrate the potential of underwater depth imaging, with specific attention given to environments with a high level of scattering. The optical system comprised a monostatic transceiver unit, a fiber-coupled supercontinuum laser source with a wavelength tunable acousto-optic filter (AOTF), and a fiber-coupled single-element silicon single-photon avalanche diode (SPAD) detector. In the optical system, the transmit and receive channels in the transceiver unit were overlapped in a coaxial optical configuration. The targets were placed in a 1.75 meter long tank, and raster scanned using two galvo-mirrors. Laboratory-based experiments demonstrate depth profiling performed with up to nine attenuation lengths between the transceiver and target. All of the measurements were taken with an average laser power of less than 1mW. Initially, the data was processed using a straightforward pixel-wise cross-correlation of the return timing signal with the system instrumental timing response. More advanced algorithms were then used to process these cross-correlation results. These results illustrate the potential for the reconstruction of images in highly scattering environments, and to permit the investigation of much shorter acquisition time scans. These algorithms take advantage of the data sparseness under the Discrete Cosine Transform (DCT) and the correlation between adjacent pixels, to restore the depth and reflectivity images.

  6. Performance of in-pixel circuits for photon counting arrays (PCAs) based on polycrystalline silicon TFTs

    Science.gov (United States)

    Liang, Albert K.; Koniczek, Martin; Antonuk, Larry E.; El-Mohri, Youcef; Zhao, Qihua; Street, Robert A.; Lu, Jeng Ping

    2016-03-01

    Photon counting arrays (PCAs), defined as pixelated imagers which measure the absorbed energy of x-ray photons individually and record this information digitally, are of increasing clinical interest. A number of PCA prototypes with a 1 mm pixel-to-pixel pitch have recently been fabricated with polycrystalline silicon (poly-Si)—a thin-film technology capable of creating monolithic imagers of a size commensurate with human anatomy. In this study, analog and digital simulation frameworks were developed to provide insight into the influence of individual poly-Si transistors on pixel circuit performance—information that is not readily available through empirical means. The simulation frameworks were used to characterize the circuit designs employed in the prototypes. The analog framework, which determines the noise produced by individual transistors, was used to estimate energy resolution, as well as to identify which transistors contribute the most noise. The digital framework, which analyzes how well circuits function in the presence of significant variations in transistor properties, was used to estimate how fast a circuit can produce an output (referred to as output count rate). In addition, an algorithm was developed and used to estimate the minimum pixel pitch that could be achieved for the pixel circuits of the current prototypes. The simulation frameworks predict that the analog component of the PCA prototypes could have energy resolution as low as 8.9% full width at half maximum (FWHM) at 70 keV; and the digital components should work well even in the presence of significant thin-film transistor (TFT) variations, with the fastest component having output count rates as high as 3 MHz. Finally, based on conceivable improvements in the underlying fabrication process, the algorithm predicts that the 1 mm pitch of the current PCA prototypes could be reduced significantly, potentially to between ~240 and 290 μm.

  7. Renal stone characterization using high resolution imaging mode on a photon counting detector CT system

    Science.gov (United States)

    Ferrero, A.; Gutjahr, R.; Henning, A.; Kappler, S.; Halaweish, A.; Abdurakhimova, D.; Peterson, Z.; Montoya, J.; Leng, S.; McCollough, C.

    2017-03-01

    In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm x 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same subelements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition. Forty pure stones - 10 uric acid (UA), 10 cystine (CYS), 10 calcium oxalate monohydrate (COM) and 10 apatite (APA) - and 14 mixed stones were placed in a 20 cm water phantom and scanned in HR mode, at radiation dose matched to that of routine dual-energy stone exams. Data from micro CT provided a reference for the quantification of morphology and mineral composition of the mixed stones. The area under the ROC curve was 1.0 for discriminating UA from CYS, 0.89 for CYS vs COM and 0.84 for COM vs APA. The root mean square error (RMSE) of the percent UA in mixed stones was 11.0% with a medium-sharp kernel and 15.6% with the sharpest kernel. The HR showed qualitatively accurate characterization of stone morphology relative to micro CT.

  8. Indirect-detection single-photon-counting x-ray detector for breast tomosynthesis

    Science.gov (United States)

    Jiang, Hao; Kaercher, Joerg; Durst, Roger

    2016-03-01

    X-ray mammography is a crucial screening tool for early identification of breast cancer. However, the overlap of anatomical features present in projection images often complicates the task of correctly identifying suspicious masses. As a result, there has been increasing interest in acquisition of volumetric information through digital breast tomosynthesis (DBT) which, compared to mammography, offers the advantage of depth information. Since DBT requires acquisition of many projection images, it is desirable that the noise in each projection image be dominated by the statistical noise of the incident x-ray quanta and not by the additive noise of the imaging system (referred to as quantum-limited imaging) and that the cumulative dose be as low as possible (e.g., no more than for a mammogram). Unfortunately, the electronic noise (~2000 electrons) present in current DBT systems based on active matrix, flat-panel imagers (AMFPIs) is still relatively high compared with modest x-ray gain of the a-Se and CsI:Tl x-ray converters often used. To overcome the modest signal-to-noise ratio (SNR) limitations of current DBT systems, we have developed a large-area x-ray imaging detector with the combination of an extremely low noise (~20 electrons) active-pixel CMOS and a specially designed high resolution scintillator. The high sensitivity and low noise of such system provides better SNR by at least an order of magnitude than current state-of-art AMFPI systems and enables x-ray indirect-detection single photon counting (SPC) at mammographic energies with the potential of dose reduction.

  9. Contrast-enhanced spectral mammography with a photon-counting detector.

    Science.gov (United States)

    Fredenberg, Erik; Hemmendorff, Magnus; Cederström, Björn; Aslund, Magnus; Danielsson, Mats

    2010-05-01

    Spectral imaging is a method in medical x-ray imaging to extract information about the object constituents by the material-specific energy dependence of x-ray attenuation. The authors have investigated a photon-counting spectral imaging system with two energy bins for contrast-enhanced mammography. System optimization and the potential benefit compared to conventional non-energy-resolved absorption imaging was studied. A framework for system characterization was set up that included quantum and anatomical noise and a theoretical model of the system was benchmarked to phantom measurements. Optimal combination of the energy-resolved images corresponded approximately to minimization of the anatomical noise, which is commonly referred to as energy subtraction. In that case, an ideal-observer detectability index could be improved close to 50% compared to absorption imaging in the phantom study. Optimization with respect to the signal-to-quantum-noise ratio, commonly referred to as energy weighting, yielded only a minute improvement. In a simulation of a clinically more realistic case, spectral imaging was predicted to perform approximately 30% better than absorption imaging for an average glandularity breast with an average level of anatomical noise. For dense breast tissue and a high level of anatomical noise, however, a rise in detectability by a factor of 6 was predicted. Another approximately 70%-90% improvement was found to be within reach for an optimized system. Contrast-enhanced spectral mammography is feasible and beneficial with the current system, and there is room for additional improvements. Inclusion of anatomical noise is essential for optimizing spectral imaging systems.

  10. Ultra-high spatial resolution multi-energy CT using photon counting detector technology

    Science.gov (United States)

    Leng, S.; Gutjahr, R.; Ferrero, A.; Kappler, S.; Henning, A.; Halaweish, A.; Zhou, W.; Montoya, J.; McCollough, C.

    2017-03-01

    Two ultra-high-resolution (UHR) imaging modes, each with two energy thresholds, were implemented on a research, whole-body photon-counting-detector (PCD) CT scanner, referred to as sharp and UHR, respectively. The UHR mode has a pixel size of 0.25 mm at iso-center for both energy thresholds, with a collimation of 32 × 0.25 mm. The sharp mode has a 0.25 mm pixel for the low-energy threshold and 0.5 mm for the high-energy threshold, with a collimation of 48 × 0.25 mm. Kidney stones with mixed mineral composition and lung nodules with different shapes were scanned using both modes, and with the standard imaging mode, referred to as macro mode (0.5 mm pixel and 32 × 0.5 mm collimation). Evaluation and comparison of the three modes focused on the ability to accurately delineate anatomic structures using the high-spatial resolution capability and the ability to quantify stone composition using the multi-energy capability. The low-energy threshold images of the sharp and UHR modes showed better shape and texture information due to the achieved higher spatial resolution, although noise was also higher. No noticeable benefit was shown in multi-energy analysis using UHR compared to standard resolution (macro mode) when standard doses were used. This was due to excessive noise in the higher resolution images. However, UHR scans at higher dose showed improvement in multi-energy analysis over macro mode with regular dose. To fully take advantage of the higher spatial resolution in multi-energy analysis, either increased radiation dose, or application of noise reduction techniques, is needed.

  11. Dual energy CT kidney stone differentiation in photon counting computed tomography

    Science.gov (United States)

    Gutjahr, R.; Polster, C.; Henning, A.; Kappler, S.; Leng, S.; McCollough, C. H.; Sedlmair, M. U.; Schmidt, B.; Krauss, B.; Flohr, T. G.

    2017-03-01

    This study evaluates the capabilities of a whole-body photon counting CT system to differentiate between four common kidney stone materials, namely uric acid (UA), calcium oxalate monohydrate (COM), cystine (CYS), and apatite (APA) ex vivo. Two different x-ray spectra (120 kV and 140 kV) were applied and two acquisition modes were investigated. The macro-mode generates two energy threshold based image-volumes and two energy bin based image-volumes. In the chesspattern-mode four energy thresholds are applied. A virtual low energy image, as well as a virtual high energy image are derived from initial threshold-based images, while considering their statistically correlated nature. The energy bin based images of the macro-mode, as well as the virtual low and high energy image of the chesspattern-mode serve as input for our dual energy evaluation. The dual energy ratio of the individually segmented kidney stones were utilized to quantify the discriminability of the different materials. The dual energy ratios of the two acquisition modes showed high correlation for both applied spectra. Wilcoxon-rank sum tests and the evaluation of the area under the receiver operating characteristics curves suggest that the UA kidney stones are best differentiable from all other materials (AUC = 1.0), followed by CYS (AUC ≍ 0.9 compared against COM and APA). COM and APA, however, are hardly distinguishable (AUC between 0.63 and 0.76). The results hold true for the measurements of both spectra and both acquisition modes.

  12. K-edge energy-based calibration method for photon counting detectors.

    Science.gov (United States)

    Ge, Yongshuai; Ji, Xu; Zhang, Ran; Li, Ke; Chen, Guang-Hong

    2017-10-26

    In recent years, potential applications of energy-resolved photon counting detectors (PCDs) in the x-ray medical imaging field have been actively investigated. Unlike conventional x-ray energy integration detectors, PCDs count the number of incident x-ray photons within certain energy windows. For PCDs, the interactions between x-ray photons and photoconductor generate electronic voltage pulse signals. The pulse height of each signal is proportional to the energy of the incident photons. By comparing the pulse height with the preset energy threshold values, x-ray photons with specific energies are recorded and sorted into different energy bins. To quantitatively understand the meaning of the energy threshold values, and thus to assign an absolute energy value to each energy bin, energy calibration is needed to establish the quantitative relationship between the threshold values and the corresponding effective photon energies. In practice, the energy calibration is not always easy, due to the lack of well-calibrated energy references for the working energy range of the PCDs. In this paper, a new method was developed to use the precise knowledge of the characteristic K-edge energy of materials to perform energy calibration. The proposed method was demonstrated using experimental data acquired from three K-edge materials (viz., iodine, gadolinium, and gold) on two different PCDs (Hydra and Flite, XCounter, Sweden). Finally, the proposed energy calibration method was further validated using a radioactive isotope (Am-241) with a known decay energy spectrum. © 2017 Institute of Physics and Engineering in Medicine.

  13. Energy-correction photon counting pixel for photon energy extraction under pulse pile-up

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Daehee; Park, Kyungjin; Lim, Kyung Taek; Cho, Gyuseong, E-mail: gscho@kaist.ac.kr

    2017-06-01

    A photon counting detector (PCD) has been proposed as an alternative solution to an energy-integrating detector (EID) in medical imaging field due to its high resolution, high efficiency, and low noise. The PCD has expanded to variety of fields such as spectral CT, k-edge imaging, and material decomposition owing to its capability to count and measure the number and the energy of an incident photon, respectively. Nonetheless, pulse pile-up, which is a superimposition of pulses at the output of a charge sensitive amplifier (CSA) in each PC pixel, occurs frequently as the X-ray flux increases due to the finite pulse processing time (PPT) in CSAs. Pulse pile-up induces not only a count loss but also distortion in the measured X-ray spectrum from each PC pixel and thus it is a main constraint on the use of PCDs in high flux X-ray applications. To minimize these effects, an energy-correction PC (ECPC) pixel is proposed to resolve pulse pile-up without cutting off the PPT by adding an energy correction logic (ECL) via a cross detection method (CDM). The ECPC pixel with a size of 200×200 µm{sup 2} was fabricated by using a 6-metal 1-poly 0.18 µm CMOS process with a static power consumption of 7.2 μW/pixel. The maximum count rate of the ECPC pixel was extended by approximately three times higher than that of a conventional PC pixel with a PPT of 500 nsec. The X-ray spectrum of 90 kVp, filtered by 3 mm Al filter, was measured as the X-ray current was increased using the CdTe and the ECPC pixel. As a result, the ECPC pixel dramatically reduced the energy spectrum distortion at 2 Mphotons/pixel/s when compared to that of the ERCP pixel with the same 500 nsec PPT.

  14. Fluorescence measurement by a streak camera in a single-photon-counting mode.

    Science.gov (United States)

    Komura, Masayuki; Itoh, Shigeru

    2009-01-01

    We describe here a recently developed fluorescence measurement system that uses a streak camera to detect fluorescence decay in a single photon-counting mode. This system allows for easy measurements of various samples and provides 2D images of fluorescence in the wavelength and time domains. The great advantage of the system is that the data can be handled with ease; furthermore, the data are amenable to detailed analysis. We describe the picosecond kinetics of fluorescence in spinach Photosystem (PS) II particles at 4-77 K as a typical experimental example. Through the global analysis of the data, we have identified a new fluorescence band (F689) in addition to the already established F680, F685, and F695 emission bands. The blue shift of the steady-state fluorescence spectrum upon cooling below 77 K can be interpreted as an increase of the shorter-wavelength fluorescence, especially F689, due to the slowdown of the excitation energy transfer process. The F685 and F695 bands seem to be thermally equilibrated at 77 K but not at 4 K. The simple and efficient photon accumulation feature of the system allows us to measure fluorescence from leaves, solutions, single colonies, and even single cells. The 2D fluorescence images obtained by this system are presented for isolated spinach PS II particles, intact leaves of Arabidopsis thaliana, the PS I super-complex of a marine centric diatom, Chaetoceros gracilis, isolated membranes of a purple photosynthetic bacterium, Acidiphilium rubrum, which contains Zn-BChl a, and a coral that contains a green fluorescent protein and an algal endosymbiont, Zooxanthella.

  15. Elemental analysis with a full-field X-ray fluorescence microscope and a CCD photon-counting system.

    Science.gov (United States)

    Ohigashi, Takuji; Watanabe, Norio; Yokosuka, Hiroki; Aota, Tatsuya; Takano, Hidekazu; Takeuchi, Akihisa; Aoki, Sadao

    2002-05-01

    The first result is presented of an X-ray fluorescence microscope with a Wolter mirror in combination with a CCD camera used as an energy-resolved two-dimensional detector in photon-counting mode. Two-dimensional elemental maps of metallic wires, such as Fe, Co, Ni and Cu, and inclusions of a synthesized diamond could be obtained with an energy resolution of 350 eV.

  16. Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation

    Science.gov (United States)

    Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

    2016-07-01

    Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems.

  17. Quantum control and process tomography of a semiconductor quantum dot hybrid qubit.

    Science.gov (United States)

    Kim, Dohun; Shi, Zhan; Simmons, C B; Ward, D R; Prance, J R; Koh, Teck Seng; Gamble, John King; Savage, D E; Lagally, M G; Friesen, Mark; Coppersmith, S N; Eriksson, Mark A

    2014-07-03

    The similarities between gated quantum dots and the transistors in modern microelectronics--in fabrication methods, physical structure and voltage scales for manipulation--have led to great interest in the development of quantum bits (qubits) in semiconductor quantum dots. Although quantum dot spin qubits have demonstrated long coherence times, their manipulation is often slower than desired for important future applications, such as factoring. Furthermore, scalability and manufacturability are enhanced when qubits are as simple as possible. Previous work has increased the speed of spin qubit rotations by making use of integrated micromagnets, dynamic pumping of nuclear spins or the addition of a third quantum dot. Here we demonstrate a qubit that is a hybrid of spin and charge. It is simple, requiring neither nuclear-state preparation nor micromagnets. Unlike previous double-dot qubits, the hybrid qubit enables fast rotations about two axes of the Bloch sphere. We demonstrate full control on the Bloch sphere with π-rotation times of less than 100 picoseconds in two orthogonal directions, which is more than an order of magnitude faster than any other double-dot qubit. The speed arises from the qubit's charge-like characteristics, and its spin-like features result in resistance to decoherence over a wide range of gate voltages. We achieve full process tomography in our electrically controlled semiconductor quantum dot qubit, extracting high fidelities of 85 per cent for X rotations (transitions between qubit states) and 94 per cent for Z rotations (phase accumulation between qubit states).

  18. Fano Effect and Quantum Entanglement in Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System

    Directory of Open Access Journals (Sweden)

    Yong He

    2017-06-01

    Full Text Available In this paper, we review the investigation for the light-matter interaction between surface plasmon field in metal nanoparticle (MNP and the excitons in semiconductor quantum dots (SQDs in hybrid SQD-MNP system under the full quantum description. The exciton-plasmon interaction gives rise to the modified decay rate and the exciton energy shift which are related to the exciton energy by using a quantum transformation method. We illustrate the responses of the hybrid SQD-MNP system to external field, and reveal Fano effect shown in the absorption spectrum. We demonstrate quantum entanglement between two SQD mediated by surface plasmon field. In the absence of a laser field, concurrence of quantum entanglement will disappear after a few ns. If the laser field is present, the steady states appear, so that quantum entanglement produced will reach a steady-state entanglement. Because one of all optical pathways to induce Fano effect refers to the generation of quantum entangled states, It is shown that the concurrence of quantum entanglement can be obtained by observation for Fano effect. In a hybrid system including two MNP and a SQD, because the two Fano quantum interference processes share a segment of all optical pathways, there is correlation between the Fano effects of the two MNP. The investigations for the light-matter interaction in hybrid SQD-MNP system can pave the way for the development of the optical processing devices and quantum information based on the exciton-plasmon interaction.

  19. Fano Effect and Quantum Entanglement in Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System.

    Science.gov (United States)

    He, Yong; Zhu, Ka-Di

    2017-06-20

    In this paper, we review the investigation for the light-matter interaction between surface plasmon field in metal nanoparticle (MNP) and the excitons in semiconductor quantum dots (SQDs) in hybrid SQD-MNP system under the full quantum description. The exciton-plasmon interaction gives rise to the modified decay rate and the exciton energy shift which are related to the exciton energy by using a quantum transformation method. We illustrate the responses of the hybrid SQD-MNP system to external field, and reveal Fano effect shown in the absorption spectrum. We demonstrate quantum entanglement between two SQD mediated by surface plasmon field. In the absence of a laser field, concurrence of quantum entanglement will disappear after a few ns. If the laser field is present, the steady states appear, so that quantum entanglement produced will reach a steady-state entanglement. Because one of all optical pathways to induce Fano effect refers to the generation of quantum entangled states, It is shown that the concurrence of quantum entanglement can be obtained by observation for Fano effect. In a hybrid system including two MNP and a SQD, because the two Fano quantum interference processes share a segment of all optical pathways, there is correlation between the Fano effects of the two MNP. The investigations for the light-matter interaction in hybrid SQD-MNP system can pave the way for the development of the optical processing devices and quantum information based on the exciton-plasmon interaction.

  20. Effective coupled optoelectrical design method for fully infiltrated semiconductor nanowires based hybrid solar cells.

    Science.gov (United States)

    Wu, Dan; Tang, Xiaohong; Wang, Kai; Li, Xianqiang

    2016-10-31

    We present a novel coupled design method that both optimizes light absorption and predicts electrical performance of fully infiltrated inorganic semiconductor nanowires (NWs) based hybrid solar cells (HSC). This method provides a thorough insight of hybrid photovoltaic process as a function of geometrical parameters of NWs. An active layer consisting of GaAs NWs as acceptor and poly(3-hexylthiophene-2,5-diyl) (P3HT) as donor were used as a design example. Absorption spectra features were studied by the evolution of the leaky modes and Fabry-Perot resonance with wavelength focusing firstly on the GaAs/air layer before extending to GaAs/P3HT hybrid active layer. The highest absorption efficiency reached 39% for the hybrid active layer of 2 μm thickness under AM 1.5G illumination. Combined with the optical absorption analysis, our method further codesigns the energy harvesting to predict electrical performance of HSC considering exciton dissociation efficiencies within both inorganic NWs and a polymeric shell of 20 nm thickness. The validity of the simulation model was also proved by the well agreement of the simulation results with the published experimental work indicating an effective guidance for future high performance HSC design.

  1. Fano Effect and Quantum Entanglement in Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System

    Science.gov (United States)

    He, Yong; Zhu, Ka-Di

    2017-01-01

    In this paper, we review the investigation for the light-matter interaction between surface plasmon field in metal nanoparticle (MNP) and the excitons in semiconductor quantum dots (SQDs) in hybrid SQD-MNP system under the full quantum description. The exciton-plasmon interaction gives rise to the modified decay rate and the exciton energy shift which are related to the exciton energy by using a quantum transformation method. We illustrate the responses of the hybrid SQD-MNP system to external field, and reveal Fano effect shown in the absorption spectrum. We demonstrate quantum entanglement between two SQD mediated by surface plasmon field. In the absence of a laser field, concurrence of quantum entanglement will disappear after a few ns. If the laser field is present, the steady states appear, so that quantum entanglement produced will reach a steady-state entanglement. Because one of all optical pathways to induce Fano effect refers to the generation of quantum entangled states, It is shown that the concurrence of quantum entanglement can be obtained by observation for Fano effect. In a hybrid system including two MNP and a SQD, because the two Fano quantum interference processes share a segment of all optical pathways, there is correlation between the Fano effects of the two MNP. The investigations for the light-matter interaction in hybrid SQD-MNP system can pave the way for the development of the optical processing devices and quantum information based on the exciton-plasmon interaction. PMID:28632165

  2. Simultaneous continuous measurement of photon-counting and homodyne detection on a free photon field: dynamics of state reduction and mutual influence of measurement backaction

    OpenAIRE

    Kuramochi, Yui; Watanabe, Yu; Ueda, Masahito

    2012-01-01

    We analyze a simultaneous continuous measurement of photon-counting and homodyne detection. The stochastic master equation or stochastic Schr\\"odinger equation describing the measurement process includes both jump-type and diffusive-type stochastic increments. Analytic expressions of the wave function conditioned on homodyne and photon-counting records are obtained, yielding the probability density distributions and generating functions of the measurement records. Formula for the expectation ...

  3. Development of ethenetetrathiolate hybrid thermoelectric materials consisting of cellulose acetate and semiconductor nanomaterials

    Science.gov (United States)

    Asano, Hitoshi; Sakura, Naoko; Oshima, Keisuke; Shiraishi, Yukihide; Toshima, Naoki

    2016-02-01

    We investigated novel organic/inorganic hybrid thermoelectric materials prepared using several metal-polymer complexes, binders (insulating polymers), and inorganic semiconductor nanomaterials. It was found that the three-component hybrid thermoelectric materials, which consisted of nanodispersed poly(nickel 1,1,2,2-ethenetetrathiolate) (Ni-PETT), cellulose acetate (CA), and carbon nanotubes (CNTs), showed high thermoelectric performance. Ni-PETT had a large negative Seebeck coefficient of -42 µV K-1 and was an n-type semiconducting polymer complex. Ni-PETT sufficiently dispersed p-type CNTs in N-methyl-2-pyrrolidone. The charge transfer interaction between Ni-PETT and CNTs could provide a strong contact. Good films could be obtained by using CA as a binder. In addition, the electrical conductivity of the three-component hybrid films was increased by methanol treatment. The Seebeck coefficient, electrical conductivity, and power factor of Ni-PETT/CA/CNT films normalized on the basis of the CNT mass were 1.9, 5.2, and 2.8 times higher than those of the CNT sheets.

  4. Progress towards photon counting between 1μm and 1.6μm using silicon with infrared absorbers

    Science.gov (United States)

    Morrison, Alan P.; Hayes, John M.; Gity, Farzan; Corbett, Brian

    2010-04-01

    Silicon based avalanche photodiodes (APDs) have exhibited impressive performance over the visible spectrum for more than a decade. Photon counting with these devices has progressed to the level where room-temperature operation and low dark count rates (< 100 Hz) are commonplace. Several commercial enterprises have been established to capitalise on these devices and many niche markets are now serviced by incorporating these devices into suitable systems. This paper describes one approach that allows the performance of silicon based Geigermode avalanche photodiodes (GM-APDs) to be extended into the near-infra-red. The process development is described whereby Ge absorbers are incorporated into adapted silicon APD designs to provide separate absorption and multiplication devices. Simulation results are presented outlining the performance of these devices at wavelengths between 1 μm and 1.6 μm. The performance results from silicon APD designs are presented for visible wavelengths. A silicon-germanium bonding process is described and the challenges presented in developing the hybrid absorber/multiplier structure are detailed. Finally, a summary of appropriate custom application integrated circuits for various applications is discussed.

  5. Hybrid bandgap engineering for super-hetero-epitaxial semiconductor materials, and products thereof

    Science.gov (United States)

    Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2012-01-01

    "Super-hetero-epitaxial" combinations comprise epitaxial growth of one material on a different material with different crystal structure. Compatible crystal structures may be identified using a "Tri-Unity" system. New bandgap engineering diagrams are provided for each class of combination, based on determination of hybrid lattice constants for the constituent materials in accordance with lattice-matching equations. Using known bandgap figures for previously tested materials, new materials with lattice constants that match desired substrates and have the desired bandgap properties may be formulated by reference to the diagrams and lattice matching equations. In one embodiment, this analysis makes it possible to formulate new super-hetero-epitaxial semiconductor systems, such as systems based on group IV alloys on c-plane LaF.sub.3; group IV alloys on c-plane langasite; Group III-V alloys on c-plane langasite; and group II-VI alloys on c-plane sapphire.

  6. Hybrid semiconductor-dielectric metamaterial modulation for switchable bi-directional THz absorbers

    Science.gov (United States)

    Le, Ly Nguyen; Thang, Nguyen Manh; Thuy, Le Minh; Tung, Nguyen Thanh

    2017-01-01

    There is an increasing interest for electromagnetic metamaterials that show mutable absorption properties with real-time and dynamic control. In this paper, we investigate a modulation of bi-directional metamaterial absorbers that is thermally switchable at terahertz frequencies. The metamaterial absorber is composed of symmetric hybrid semiconductor-dielectric cut-wire-pair structures, whose electromagnetic responses can be actively manipulated by utilizing an external heat source. As increasing the temperature of metamaterials from 300 to 350 K, we demonstrate that the magnetic resonance can be systematically blue-shifted and overlapped with the electric resonance, which is unaffectedly settled at about 0.8 THz. This superposition provides an effective mechanism to control the absorption intensity from 43% to nearly 95%. Finite integration simulation technique, standard retrieval method, and equivalent circuit model are employed to elaborate our idea.

  7. Tuning the band gap in hybrid tin iodide perovskite semiconductors using structural templating.

    Science.gov (United States)

    Knutson, Jeremy L; Martin, James D; Mitzi, David B

    2005-06-27

    Structural distortions within the extensive family of organic/inorganic hybrid tin iodide perovskite semiconductors are correlated with their experimental exciton energies and calculated band gaps. The extent of the in- and out-of-plane angular distortion of the SnI4(2-) perovskite sheets is largely determined by the relative charge density and steric requirements of the organic cations. Variation of the in-plane Sn-I-Sn bond angle was demonstrated to have the greatest impact on the tuning of the band gap, and the equatorial Sn-I bond distances have a significant secondary influence. Extended Hückel tight-binding band calculations are employed to decipher the crystal orbital origins of the structural effects that fine-tune the band structure. The calculations suggest that it may be possible to tune the band gap by as much as 1 eV using the templating influence of the organic cation.

  8. Spin-resolved Andreev levels and parity crossings in hybrid superconductor-semiconductor nanostructures.

    Science.gov (United States)

    Lee, Eduardo J H; Jiang, Xiaocheng; Houzet, Manuel; Aguado, Ramón; Lieber, Charles M; De Franceschi, Silvano

    2014-01-01

    The physics and operating principles of hybrid superconductor-semiconductor devices rest ultimately on the magnetic properties of their elementary subgap excitations, usually called Andreev levels. Here we report a direct measurement of the Zeeman effect on the Andreev levels of a semiconductor quantum dot with large electron g-factor, strongly coupled to a conventional superconductor with a large critical magnetic field. This material combination allows spin degeneracy to be lifted without destroying superconductivity. We show that a spin-split Andreev level crossing the Fermi energy results in a quantum phase transition to a spin-polarized state, which implies a change in the fermionic parity of the system. This crossing manifests itself as a zero-bias conductance anomaly at finite magnetic field with properties that resemble those expected for Majorana modes in a topological superconductor. Although this resemblance is understood without evoking topological superconductivity, the observed parity transitions could be regarded as precursors of Majorana modes in the long-wire limit.

  9. Photon-counting hexagonal pixel array CdTe detector: Spatial resolution characteristics for image-guided interventional applications

    Energy Technology Data Exchange (ETDEWEB)

    Vedantham, Srinivasan; Shrestha, Suman; Karellas, Andrew, E-mail: andrew.karellas@umassmed.edu; Shi, Linxi; Gounis, Matthew J. [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States); Bellazzini, Ronaldo; Spandre, Gloria; Brez, Alessandro; Minuti, Massimo [Istituto Nazionale di Fisica Nucleare (INFN), Pisa 56127, Italy and Pixirad Imaging Counters s.r.l., L. Pontecorvo 3, Pisa 56127 (Italy)

    2016-05-15

    Purpose: High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. Methods: A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. Results: At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54

  10. Photon-counting hexagonal pixel array CdTe detector: Spatial resolution characteristics for image-guided interventional applications

    Science.gov (United States)

    Shrestha, Suman; Karellas, Andrew; Shi, Linxi; Gounis, Matthew J.; Bellazzini, Ronaldo; Spandre, Gloria; Brez, Alessandro; Minuti, Massimo

    2016-01-01

    Purpose: High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. Methods: A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. Results: At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54

  11. Multi-physics analysis of hybrid graphene/semiconductor plasmonic terahertz sources (Conference Presentation)

    Science.gov (United States)

    Nafari, Mona; Aizin, Gregory R.; Jornet, Josep M.

    2017-05-01

    Wireless data rates have doubled every eighteen months for the last three decades. Following this trend, Terabit-per-second links will become a reality within the next five years. In this context, Terahertz (THz) band (0.1-10 THz) communication is envisioned as a key technology of the next decade. Despite major progress towards developing THz sources, compact signal generators above 1 THz able to efficiently work at room temperature are still missing. Recently, the use of hybrid graphene/semiconductor high-electron-mobility transistors (HEMT) has been proposed as a way to generate Surface Plasmon Polariton (SPP) waves at THz frequencies. Compact size, room-temperature operation and tunability of the graphene layer, in addition to possibility for large scale integration, motivate the exploration of this approach. In this paper, a simulation model of hybrid graphene/semiconductor HEMT-based THz sources is developed. More specifically, first, the necessary conditions for the so-called Dyakonov-Shur instability to arise within the HEMT channel are derived, and the impact of imperfect boundary conditions is analyzed. Second, the required conditions for coupling between a confined plasma wave in the HEMT channel and a SPP wave in graphene are derived, by starting from the coupling analysis between two 2DEG. Multi-physics simulation are conducted by integrating the hydrodynamic equations for the description of the HEMT device with Maxwell's equations for SPP modeling. Extensive results are provided to analyze the impact of different design elements on the THz signal source. This work will guide the experimental fabrication and characterization of the devices.

  12. Detection of microcalcifications and tumor tissue in mammography using a CdTe-series photon-counting detector

    Science.gov (United States)

    Nakajima, Ai; Ihori, Akiko; Nishide, Hiroko; Koyama, Shuji; Yamakawa, Tsutomu; Yamamoto, Shuichiro; Okada, Masahiro; Kodera, Yoshie

    2017-03-01

    In this study, we proposed a method for detecting microcalcifications and tumor tissue using a cadmium telluride (CdTe) series linear detector. The CdTe series detector was used as an energy resolved photon-counting (hereafter referred to as the photon-counting) mammography detector. The CdTe series linear detector and two types of phantom were designed using a MATLAB simulation. Each phantom consisted of mammary gland and adipose tissue. One phantom contained microcalcifications and the other contained tumor tissue. We varied the size of these structures and the mammary gland composition. We divided the spectrum of an x-ray, which is transmitted to each phantom, into three energy bins and calculated the corresponding linear attenuation coefficients from the numbers of input and output photons. Subsequently, the absorption vector length that expresses the amount of absorption was calculated. When the material composition was different between objects, for example mammary gland and microcalcifications, the absorption vector length was also different. We compared each absorption vector length and tried to detect the microcalcifications and tumor tissue. However, as the size of microcalcifications and tumor tissue decreased and/or the mammary gland content rate increased, there was difficulty in distinguishing them. The microcalcifications and tumor tissue despite the reduction in size or increase in mammary gland content rate can be distinguished by increasing the x-ray dosage. Therefore, it is necessary to find a condition under which a low exposure dose is optimally balanced with high detection sensitivity. It is a new method to indicate the image using photon counting technology.

  13. A photon counting dynamic digital lock-in amplifier for background suppression in glow discharge atomic emission spectrometry

    Science.gov (United States)

    Gökmen, Ali; Ulgen, Ahmet; Yalçin, Şerife

    1996-01-01

    A photon counting dynamic digital lock-in amplifier, (PC-DDLIA), has been developed for the suppression of Ar lines in glow discharge lamp atomic emission spectrometry, (GDL-AES). The experimental set-up consists of a Grimm-type GDL, a prism-type scanning monochromator, photon counting electronics, an Apple Ile computer with an interface card and a computer controllable high voltage power supply. The photon counting electronics are designed to convert the photon pulses to logic pulses. A discriminator is used to reject pulses below a threshold level. The high voltage power supply is modulated with a square waveform generated from DAC and photon pulses are counted synchronously by the timer/counter chip, versatile interface adaptor (VIA-6522) on the interface card of computer. The data are analyzed in two steps. In the "learn mode", the GDL is modulated with a square waveform between 370 and 670 V and two spectra consisting of only Ar lines are obtained in a spectral window between 287.1 and 290.0 nm. A new modulation waveform is computed from these spectra which yields two overlapped spectra when the PC-DDLIA is scanned over the same spectral window. In the "analysis mode" of data acquisition, a target material with the analyte element(s) in it is used and the spectrometer is scanned with a dynamically varying rectangular waveform over the same spectral window. The net spectrum consists of pure atomic lines free from any Ar lines. The detection limit for the determination of Si (288.2 nm) in the presence of interfering Ar lines (288.1 and 288.4 nm) is found to be 0.083%, whereas suppression of Ar lines over the same spectral window lowers the detection limit to 0.013%.

  14. Mode-Selective Photon Counting Via Quantum Frequency Conversion Using Spectrally-Engineered Pump Pulses

    Science.gov (United States)

    Manurkar, Paritosh

    phase of each spectral frequency from an optical frequency comb. The latter is generated using a cascaded configuration of phase and amplitude modulators. We characterize the mode selectivity using classical signals by arranging the six TMs into two orthogonal signal sets. Furthermore, we also demonstrate that mode selectivity is preserved if we use sub-photon signals (weak coherent light). Thus, this work supports the idea that QFC has the basic properties needed for advanced multi-dimensional quantum measurements given that we have demonstrated for the first time the ability to move to high dimensions (d=4), measure coherent superposition modes, and measure sub-photon signal levels. In addition to mode-selective photon counting, we also experimentally demonstrate a method of reshaping optical pulses based on QFC. Such a method has the potential to serve as the interface between quantum memories and the existing fiber infrastructure. At the same time, it can be employed in all-optical systems for optical signal regeneration.

  15. Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors.

    Science.gov (United States)

    Bergamaschi, Anna; Dinapoli, Roberto; Greiffenberg, Dominic; Henrich, Beat; Johnson, Ian; Mozzanica, Aldo; Radicci, Valeria; Schmitt, Bernd; Shi, Xintian; Stoppani, Laura

    2011-11-01

    The MYTHEN single-photon-counting (SPC) detector has been characterized using the time-over-threshold (ToT) readout method, i.e. measuring the time that the signal produced by the detected X-rays remains above the comparator threshold. In the following it is shown that the ToT readout preserves the sensitivity, dynamic range and capability of background suppression of the SPC mode, while enhancing the count-rate capability, which is the main limitation of state-of-the-art SPC systems.

  16. Quantum Non-Demolition Photon Counting and Time-Resolved Reconstruction of Non-Classical Field States in a Cavity

    Science.gov (United States)

    Haroche, S.; Deleglise, S.; Sayrin, C.; Bernu, J.; Gleyzes, S.; Guerlin, C.; Kuhr, S.; Dotsenko, I.; Brune, M.; Raimond, J. M.

    2009-03-01

    We describe Cavity QED experiments in which a beam of circular Rydberg atoms is used to manipulate and probe non-destructively microwave photons trapped in a very high-Q superconducting cavity. We realize an ideal quantum non-demolition (QND) measurement of light, observe the radiation quantum jumps due to cavity relaxation and prepare non-classical fields such as Fock and Schrödinger cat states. Combining QND photon counting with a homodyne mixing method, we reconstruct the Wigner functions of these non-classical states and, by taking snapshots of these functions at increasing times, obtain movies of the decoherence process in the cavity.

  17. Feasibility of using single photon counting X-ray for lung tumor position estimation based on 4D-CT

    Energy Technology Data Exchange (ETDEWEB)

    Aschenbrenner, Katharina P.; Hesser, Juergen W. [Heidelberg Univ., Mannheim (Germany). Dept. of Experimental Radiation Oncology; Heidelberg Univ. (Germany). IWR; Guthier, Christian V. [Heidelberg Univ., Mannheim (Germany). Dept. of Experimental Radiation Oncology; Lyatskaya, Yulia [Brigham and Women' s Center, Boston, MA (United States); Harvard Medical School, Boston, MA (United States); Boda-Heggemann, Judit; Wenz, Frederik [Heidelberg Univ., Mannheim (Germany). Dept. of Radiation Oncology

    2017-10-01

    In stereotactic body radiation therapy of lung tumors, reliable position estimation of the tumor is necessary in order to minimize normal tissue complication rate. While kV X-ray imaging is frequently used, continuous application during radiotherapy sessions is often not possible due to concerns about the additional dose. Thus, ultra low-dose (ULD) kV X-ray imaging based on a single photon counting detector is suggested. This paper addresses the lower limit of photons to locate the tumor reliably with an accuracy in the range of state-of-the-art methods, i.e. a few millimeters. 18 patient cases with four dimensional CT (4D-CT), which serves as a-priori information, are included in the study. ULD cone beam projections are simulated from the 4D-CTs including Poisson noise. The projections from the breathing phases which correspond to different tumor positions are compared to the ULD projection by means of Poisson log-likelihood (PML) and correlation coefficient (CC), and template matching under these metrics. The results indicate that in full thorax imaging five photons per pixel suffice for a standard deviation in tumor positions of less than half a breathing phase. Around 50 photons per pixel are needed to achieve this accuracy with the field of view restricted to the tumor region. Compared to CC, PML tends to perform better for low photon counts and shifts in patient setup. Template matching only improves the position estimation in high photon counts. The quality of the reconstruction is independent of the projection angle. The accuracy of the proposed ULD single photon counting system is in the range of a few millimeters and therefore comparable to state-of-the-art tumor tracking methods. At the same time, a reduction in photons per pixel by three to four orders of magnitude relative to commercial systems with flatpanel detectors can be achieved. This enables continuous kV image-based position estimation during all fractions since the additional dose to the

  18. Hybrid solar cells based on semiconductor nanocrystals and poly(3-hexylthiophene)

    Energy Technology Data Exchange (ETDEWEB)

    Borchert, Holger; Witt, Florian; Kruszynska, Marta; Radychev, Nikolai; Lokteva, Irina; Zutz, Folker; Heinemann, Marc Daniel; Hauff, Elizabeth von; Kolny-Olesiak, Joanna; Riedel, Ingo; Parisi, Juergen [University of Oldenburg (Germany). Department of Physics, Energy and Semiconductor Research Laboratory

    2010-07-01

    Semiconductor nanoparticles are promising electron acceptor materials for polymer-based bulk heterojunction solar cells. Size-dependent optical properties enable adaptation of the absorption to the solar spectrum, and the possibility to use elongated nanoparticles should be favorable for efficient electron transport. Despite these potential advantages, efficiencies reported for such hybrid solar cells are still below those of organic polymer/fullerene cells. In the presented work, CdSe nanoparticles were prepared by colloidal chemistry and their usability for hybrid solar cells in conjunction with poly(3-hexylthiophene) (P3HT) as electron donor material was studied. Systematic studies of correlations between the device performance and blend morphology are presented. Furthermore, charge separation in the donor/acceptor systems was studied in detail by electron spin resonance (ESR) and photoinduced absorption spectroscopy (PIA). The studies revealed the existence of a large amount of trap states which might be the origin of the limitations for the device efficiency. First results with colloidally prepared CuInS{sub 2} nanoparticles are presented as well.

  19. Influence of Semiconductor Nanocrystal Concentration on Polymer Hole Transport in Hybrid Nanocomposites

    Directory of Open Access Journals (Sweden)

    Ryan Pate

    2012-01-01

    Full Text Available This article investigates hole transport in poly[2-methoxy-5-(2'-ethyl-hexyloxy-1,4-phenylene vinylene] (MEH-PPV/CdSe colloidal quantum dot (CQD nanocomposites using a modified time-of-flight photoconductivity technique. The measured hole drift mobilities are analyzed in the context of Bässler’s Gaussian disorder model and the correlated disorder model in order to determine the polymer internal morphology of hybrid nanocomposite thin films. This work shows that increasing the CdSe CQD concentration decreases the polymer hole mobility from ~5.9 × 10−6 cm2/Vs in an MEH-PPV film to ~8.1 × 10−8 cm2/Vs in a 20:80 (wt% MEH-PPV:CdSe CQD nanocomposite film (measured at 25 °C and ~2 × 105 V/cm. The corresponding disorder parameters indicate increasing disruption of interchain interaction with increasing CQD concentration. This work quantifies polymer chain morphology in hybrid nanocomposite thin films and provides useful information regarding the optimal use of semiconductor nanocrystals in conjugated polymer-based optoelectronics.

  20. Technical feasibility proof for high-resolution low-dose photon-counting CT of the breast

    Energy Technology Data Exchange (ETDEWEB)

    Kalender, Willi A.; Kolditz, Daniel; Lueck, Ferdinand [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); CT Imaging GmbH, Erlangen (Germany); Steiding, Christian [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); CT Imaging GmbH, Erlangen (Germany); University Hospital of Erlangen, Institute of Radiology, Erlangen (Germany); Ruth, Veikko; Roessler, Ann-Christin [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); Wenkel, Evelyn [University Hospital of Erlangen, Institute of Radiology, Erlangen (Germany)

    2017-03-15

    X-ray computed tomography (CT) has been proposed and evaluated multiple times as a potentially alternative method for breast imaging. All efforts shown so far have been criticized and partly disapproved because of their limited spatial resolution and higher patient dose when compared to mammography. Our concept for a dedicated breast CT (BCT) scanner therefore aimed at novel apparatus and detector design to provide high spatial resolution of about 100 μm and average glandular dose (AGD) levels of 5 mGy or below. Photon-counting technology was considered as a solution to reach these goals. The complete concept was previously evaluated and confirmed by simulations and basic experiments on laboratory setups. We here present measurements of dose, technical image quality parameters and surgical specimen results on such a scanner. For comparison purposes, the specimens were also imaged with digital mammography (DM) and breast tomosynthesis (BT) apparatus. Results show that photon-counting BCT (pcBCT) at 5 mGy AGD offers sufficiently high 3D spatial resolution for reliable detectability of calcifications and soft tissue delineation. (orig.)

  1. X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

    Science.gov (United States)

    Dudak, J.; Karch, J.; Holcova, K.; Zemlicka, J.

    2017-12-01

    As X-ray micro-CT became a popular tool for scientific purposes a number of commercially available CT systems have emerged on the market. Micro-CT systems have, therefore, become widely accessible and the number of research laboratories using them constantly increases. However, even when CT scans with spatial resolution of several micrometers can be performed routinely, data acquisition with sub-micron precision remains a complicated task. Issues come mostly from prolongation of the scan time inevitably connected with the use of nano-focus X-ray sources. Long exposure time increases the noise level in the CT projections. Furthermore, considering the sub-micron resolution even effects like source-spot drift, rotation stage wobble or thermal expansion become significant and can negatively affect the data. The use of dark-current free photon counting detectors as X-ray cameras for such applications can limit the issue of increased image noise in the data, however the mechanical stability of the whole system still remains a problem and has to be considered. In this work we evaluate the performance of a micro-CT system equipped with nano-focus X-ray tube and a large area photon counting detector Timepix for scans with effective pixel size bellow one micrometer.

  2. Low-Noise Free-Running High-Rate Photon-Counting for Space Communication and Ranging

    Science.gov (United States)

    Lu, Wei; Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Merritt, Scott

    2016-01-01

    We present performance data for low-noise free-running high-rate photon counting method for space optical communication and ranging. NASA GSFC is testing the performance of two types of novel photon-counting detectors 1) a 2x8 mercury cadmium telluride (HgCdTe) avalanche array made by DRS Inc., and a 2) a commercial 2880-element silicon avalanche photodiode (APD) array. We successfully measured real-time communication performance using both the 2 detected-photon threshold and logic AND-gate coincidence methods. Use of these methods allows mitigation of dark count, after-pulsing and background noise effects without using other method of Time Gating The HgCdTe APD array routinely demonstrated very high photon detection efficiencies (50) at near infrared wavelength. The commercial silicon APD array exhibited a fast output with rise times of 300 ps and pulse widths of 600 ps. On-chip individually filtered signals from the entire array were multiplexed onto a single fast output. NASA GSFC has tested both detectors for their potential application for space communications and ranging. We developed and compare their performances using both the 2 detected photon threshold and coincidence methods.

  3. Development of nanostructured and surface modified semiconductors for hybrid organic-inorganic solar cells.

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Julia, W. P.

    2008-09-01

    Solar energy conversion is increasingly being recognized as one of the principal ways to meet future energy needs without causing detrimental environmental impact. Hybrid organic-inorganic solar cells (SCs) are attracting particular interest due to the potential for low cost manufacturing and for use in new applications, such as consumer electronics, architectural integration and light-weight sensors. Key materials advantages of these next generation SCs over conventional semiconductor SCs are in design opportunities--since the different functions of the SCs are carried out by different materials, there are greater materials choices for producing optimized structures. In this project, we explore the hybrid organic-inorganic solar cell system that consists of oxide, primarily ZnO, nanostructures as the electron transporter and poly-(3-hexylthiophene) (P3HT) as the light-absorber and hole transporter. It builds on our capabilities in the solution synthesis of nanostructured semiconducting oxide arrays to this photovoltaic (PV) technology. The three challenges in this hybrid material system for solar applications are (1) achieving inorganic nanostructures with critical spacing that matches the exciton diffusion in the polymer, {approx} 10 nm, (2) infiltrating the polymer completely into the dense nanostructure arrays, and (3) optimizing the interfacial properties to facilitate efficient charge transfer. We have gained an understanding and control over growing oriented ZnO nanorods with sub-50 nm diameters and the required rod-to-rod spacing on various substrates. We have developed novel approaches to infiltrate commercially available P3HT in the narrow spacing between ZnO nanorods. Also, we have begun to explore ways to modify the interfacial properties. In addition, we have established device fabrication and testing capabilities at Sandia for prototype devices. Moreover, the control synthesis of ZnO nanorod arrays lead to the development of an efficient anti

  4. Assessing the performance of self-consistent hybrid functional for band gap calculation in oxide semiconductors.

    Science.gov (United States)

    He, Jiangang; Franchini, Cesare

    2017-08-16

    In this paper we assess the predictive power of the self-consistent hybrid functional scPBE0 in calculating the band gap of oxide semiconductors. The computational procedure is based on the self-consistent evaluation of the mixing parameter α by means of an iterative calculation of the static dielectric constant using the perturbation expansion after discretization (PEAD) method and making use of the relation α = 1/ε. Our materials dataset is formed by 30 compounds covering a wide range of band gaps and dielectric properties, and includes materials with a wide spectrum of application as thermoelectrics, photocatalysis, photovoltaics, transparent conducting oxides, and refractory materials. Our results show that the scPBE0 functional provides better band gaps than the non self-consistent hybrids PBE0 and HSE06, but scPBE0 does not show significant improvement on the description of the static dielectric constants. Overall, the scPBE0 data exhibit a mean absolute percentage error of 14 % (band gaps) and 10 % (α = 1/ε). For materials with weak dielectric screening and large excitonic biding energies scPBE0, unlike PBE0 and HSE06, overestimates the band gaps, but the value of the gap become very close to the experimental value when excitonic effects are included (e.g. for SiO2). However, special caution must be given to the compounds with small band gaps due to the tendency of scPBE0 to overestimate the dielectric constant in proximity of the metallic limit. © 2017 IOP Publishing Ltd.

  5. Comparative Study of the Photocatalytic Activity of Semiconductor Nanostructures and Their Hybrid Metal Nanocomposites on the Photodegradation of Malathion

    Directory of Open Access Journals (Sweden)

    Dina Mamdouh Fouad

    2012-01-01

    Full Text Available This work is devoted to synthesize different semiconductor nanoparticles and their metal-hybrid nanocomposites such as TiO2, Au/TiO2, ZnO, and Au/ZnO. The morphology and crystal structure of the prepared nanomaterials are characterized by the TEM and XRD, respectively. These materials are used as catalysts for the photodegradation of Malathion which is one of the most commonly used pesticides in the developing countries. The degradation of 10 ppm Malathion under ultraviolet (UV and visible light in the presence of the different synthesized nanocomposites was analyzed with high-performance liquid chromatography (HPLC and UV-Visible Spectra. A comprehensive study is carried out for the catalytic efficiency of the prepared nanoparticles. Different factors influencing the catalytic photodegradation are investigated, as different light source, surface coverage, and nature of the organic contaminants. The results indicate that hybrid nanocomposite of the semiconductor-metal hybrid serves as a better catalytic system compared with semiconductor nanoparticles themselves.

  6. Influence of structural fluctuations on lifetimes of adsorbate states at hybrid organic-semiconductor interfaces

    Science.gov (United States)

    Müller, M.; Sánchez-Portal, D.; Lin, H.; Fratesi, G.; Brivio, G. P.; Selloni, A.

    On the road towards a more realistic description of charge transfer processes at hybrid organic-semiconductor interfaces for photovoltaic applications we extend our first-principles scheme for the extraction of elastic linewidths to include the effects of structural fluctuations. Based on snapshots obtained from Car-Parinello molecular dynamics simulations at room temperature, we set up geometries in which dye molecules at interfaces are attached to a semi-infinite TiO2 substrate. The elastic linewidths are computed using a Green's function method. This effectively introduces the coupling to a continuum of states in the substrate. In particular we investigate catechol and isonicotinic acid on rutile(110) and anatase(101) at the level of semi-local density functional theory. We perform multiple calculations of linewidths and peak-positions associated with the adsorbate's frontier orbitals for different geometric configurations to obtain a time-averaged analysis of such physical properties. We compare the results from the considered systems to understand the effects of dynamics onto interfacial charge transfer and systematically assess the dependence of the extracted elastic lifetimes on the relative alignment between adsorbate and substrate states. This project has received funding from the European Union Seventh Framework Programme under Grant Agreement No. 607323 [THINFACE].

  7. Evaluation of semiconductor devices for Electric and Hybrid Vehicle (EHV) ac-drive applications, volume 1

    Science.gov (United States)

    Lee, F. C.; Chen, D. Y.; Jovanovic, M.; Hopkins, D. C.

    1985-01-01

    The results of evaluation of power semiconductor devices for electric hybrid vehicle ac drive applications are summarized. Three types of power devices are evaluated in the effort: high power bipolar or Darlington transistors, power MOSFETs, and asymmetric silicon control rectifiers (ASCR). The Bipolar transistors, including discrete device and Darlington devices, range from 100 A to 400 A and from 400 V to 900 V. These devices are currently used as key switching elements inverters for ac motor drive applications. Power MOSFETs, on the other hand, are much smaller in current rating. For the 400 V device, the current rating is limited to 25 A. For the main drive of an electric vehicle, device paralleling is normally needed to achieve practical power level. For other electric vehicle (EV) related applications such as battery charger circuit, however, MOSFET is advantageous to other devices because of drive circuit simplicity and high frequency capability. Asymmetrical SCR is basically a SCR device and needs commutation circuit for turn off. However, the device poses several advantages, i.e., low conduction drop and low cost.

  8. Design of a high-bandwidth data recording and quicklook display system for a photon-counting speckle camera

    Science.gov (United States)

    Eichhorn, Guenther; Hege, E. Keith

    1990-08-01

    The computer system described in this paper is designed to capture event data from a photon-counting speckle camera at photon event rates of up to 1 MHz continuously. The display and quicklook computer uses several single board computers (SBC's) to display the photon events in real-time, calculate the centroid of the data for autoguiding of the telescope, and calculate the autocorrelation function. The system is based on the VMEbus architecture. The SBC's operate under the VxWorks real-time operating system. A Sun workstation is used for code development. the SBC's are mostly selected for speed since the computational requirements are very high. Eventually a Sun workstation for near-real-time image processing and image reconstruction will be used to receive quicklook data from the control computer.

  9. Analysis of time-correlated single photon counting data: a comparative evaluation of deterministic and probabilistic approaches

    Science.gov (United States)

    Smith, Darren A.; McKenzie, Grant; Jones, Anita C.; Smith, Trevor A.

    2017-12-01

    We review various methods for analysing time-resolved fluorescence data acquired using the time-correlated single photon counting method in an attempt to evaluate their benefits and limitations. We have applied these methods to both experimental and simulated data. The relative merits of using deterministic approaches, such as the commonly used iterative reconvolution method, and probabilistic approaches, such as the smoothed exponential series method, the maximum entropy method and recently proposed basis pursuit denoising (compressed sensing) method, are outlined. In particular, we show the value of using multiple methods to arrive at the most appropriate choice of model. We show that the use of probabilistic analysis methods can indicate whether a discrete component or distribution analysis provides the better representation of the data.

  10. Wide-field time-correlated single photon counting (TCSPC) microscopy with time resolution below the frame exposure time

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M. [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Petrášek, Zdeněk [Max Planck Institute of Biochemistry, Department of Cellular and Molecular Biophysics, Am Klopferspitz 18, D-82152 Martinsried (Germany); Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom)

    2015-07-01

    Fast frame rate CMOS cameras in combination with photon counting intensifiers can be used for fluorescence imaging with single photon sensitivity at kHz frame rates. We show here how the phosphor decay of the image intensifier can be exploited for accurate timing of photon arrival well below the camera exposure time. This is achieved by taking ratios of the intensity of the photon events in two subsequent frames, and effectively allows wide-field TCSPC. This technique was used for measuring decays of ruthenium compound Ru(dpp) with lifetimes as low as 1 μs with 18.5 μs frame exposure time, including in living HeLa cells, using around 0.1 μW excitation power. We speculate that by using an image intensifier with a faster phosphor decay to match a higher camera frame rate, photon arrival time measurements on the nanosecond time scale could well be possible.

  11. Absolute dose calibration of an X-ray system and dead time investigations of photon-counting techniques

    CERN Document Server

    Carpentieri, C; Ludwig, J; Ashfaq, A; Fiederle, M

    2002-01-01

    High precision concerning the dose calibration of X-ray sources is required when counting and integrating methods are compared. The dose calibration for a dental X-ray tube was executed with special dose calibration equipment (dosimeter) as function of exposure time and rate. Results were compared with a benchmark spectrum and agree within +-1.5%. Dead time investigations with the Medipix1 photon-counting chip (PCC) have been performed by rate variations. Two different types of dead time, paralysable and non-paralysable will be discussed. The dead time depends on settings of the front-end electronics and is a function of signal height, which might lead to systematic defects of systems. Dead time losses in excess of 30% have been found for the PCC at 200 kHz absorbed photons per pixel.

  12. Picosecond wide-field time-correlated single photon counting fluorescence microscopy with a delay line anode detector

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M.; Le Marois, Alix; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Becker, Wolfgang; Smietana, Stefan [Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Milnes, James; Conneely, Thomas [Photek Ltd., 26 Castleham Rd, Saint Leonards-on-Sea TN38 9NS (United Kingdom); Jagutzki, Ottmar [Institut für Kernphysik, Max-von-Laue-Str. 1, 60438 Frankfurt (Germany)

    2016-08-15

    We perform wide-field time-correlated single photon counting-based fluorescence lifetime imaging (FLIM) with a crossed delay line anode image intensifier, where the pulse propagation time yields the photon position. This microchannel plate-based detector was read out with conventional fast timing electronics and mounted on a fluorescence microscope with total internal reflection (TIR) illumination. The picosecond time resolution of this detection system combines low illumination intensity of microwatts with wide-field data collection. This is ideal for fluorescence lifetime imaging of cell membranes using TIR. We show that fluorescence lifetime images of living HeLa cells stained with membrane dye di-4-ANEPPDHQ exhibit a reduced lifetime near the coverslip in TIR compared to epifluorescence FLIM.

  13. Optimization of the equalization procedure for a single-photon counting CdTe detector used for CT

    Science.gov (United States)

    Delogu, P.; Brombal, L.; Di Trapani, V.; Donato, S.; Bottigli, U.; Dreossi, D.; Golosio, B.; Oliva, P.; Rigon, L.; Longo, R.

    2017-11-01

    SYRMA-3D (SYnchrotron Radiation MAmmography 3D) aims to develop a breast CT system based on monochromatic synchrotron radiation and a single photon counting detector (PIXIRAD-8) with CdTe sensor. Due to the demanding requests on high contrast resolution and low dose, images in breast CT are particularly sensitive to small imperfections of the flat field correction applied before the CT reconstruction. Detectors based on high Z crystal sensors show inhomogeneous pixels gain, which depends on the time from the switching-on of the high voltage polarization. This effect has been studied in our CdTe detector with the purpose of develop an effective flat field correction procedure. In the PIXIRAD-8 detector, the time-dependent inhomogeneities of the flat field signal appear to be local, small and systematically reproducible, with the exception of the pixels on the sensors edges.

  14. Development of windows based software to analyze fluorescence decay with time-correlated single photon counting (TCSPC) setup

    CERN Document Server

    Mallick, M B; Ravindranath, S V G

    2002-01-01

    A VUV spectroscopic facility for studies in photophysics and photochemistry is being set up at INDUS-I synchrotron source, CAT, Indore. For this purpose, a data acquisition system based on time-correlated single photon counting method is being developed for fluorescence lifetime measurement. To estimate fluorescence lifetime from the data collected with this sytem, a Windows based program has been developed using Visual Basic 5.0. It uses instrument response function (IRF) and observed decay curve and estimates parameters of single exponential decay by least square analysis and Marquardt method as convergence mechanism. Estimation of parameters was performed using data collected with a commercial setup. Goodness of fit was judged by evaluating chi R sup 2 , weighted residuals and autocorrelation function. Performance is compared with two commercial software packages and found to be satisfactory.

  15. Development of a fast read-out system of a single photon counting detector for mammography with synchrotron radiation

    Science.gov (United States)

    Lopez, F. C.; Rigon, L.; Longo, R.; Arfelli, F.; Bergamaschi, A.; Chen, R. C.; Dreossi, D.; Schmitt, B.; Vallazza, E.; Castelli, E.

    2011-12-01

    A single-photon counting detector read-out system for mammography with synchrotron radiation has been developed with the aim to meet the needs of the mammographic imaging station of the SYRMEP beamline at ELETTRA. The system called PICASSO (Phase Imaging for Clinical Application with Silicon detector and Synchrotron radiatiOn) is a modular detector that implements a read-out system with MYTHEN II ASICs, an embedded Linux-based controller board and a Scientific Linux acquisition workstation. The system architecture and characteristics are herein presented. The system was tested at the SYRMEP beamline and achieved a frame rate of 33 Hz for 8448 channels at 24-bit dynamic range, and it is capable of continuously acquiring up to 2000 frames. Standard mammographic phantoms were imaged and good quality images were obtained at doses comparable with what is delivered in conventional full field mammographic systems.

  16. Studying the optical second-order interference pattern formation process with classical light in the photon counting regime.

    Science.gov (United States)

    He, Yuchen; Liu, Jianbin; Zhang, Songlin; Wang, Wentao; Bai, Bin; Le, Mingnan; Xu, Zhuo

    2015-12-01

    The formation process of the second-order interference pattern is studied experimentally in the photon counting regime by superposing two independent single-mode continuous-wave lasers. Two-photon interference based on the superposition principle in Feynman's path integral theory is employed to interpret the experimental results. The second-order interference pattern of classical light can be formulated when, with high probability, there are only two photons in the interferometer at one time. The studies are helpful in understanding the second-order interference of classical light in the language of photons. The method and conclusions can be generalized to the third- and higher-order interference of light and interference of massive particles.

  17. Spectral performance of a whole-body research photon counting detector CT: quantitative accuracy in derived image sets

    Science.gov (United States)

    Leng, Shuai; Zhou, Wei; Yu, Zhicong; Halaweish, Ahmed; Krauss, Bernhard; Schmidt, Bernhard; Yu, Lifeng; Kappler, Steffen; McCollough, Cynthia

    2017-09-01

    Photon-counting computed tomography (PCCT) uses a photon counting detector to count individual photons and allocate them to specific energy bins by comparing photon energy to preset thresholds. This enables simultaneous multi-energy CT with a single source and detector. Phantom studies were performed to assess the spectral performance of a research PCCT scanner by assessing the accuracy of derived images sets. Specifically, we assessed the accuracy of iodine quantification in iodine map images and of CT number accuracy in virtual monoenergetic images (VMI). Vials containing iodine with five known concentrations were scanned on the PCCT scanner after being placed in phantoms representing the attenuation of different size patients. For comparison, the same vials and phantoms were also scanned on 2nd and 3rd generation dual-source, dual-energy scanners. After material decomposition, iodine maps were generated, from which iodine concentration was measured for each vial and phantom size and compared with the known concentration. Additionally, VMIs were generated and CT number accuracy was compared to the reference standard, which was calculated based on known iodine concentration and attenuation coefficients at each keV obtained from the U.S. National Institute of Standards and Technology (NIST). Results showed accurate iodine quantification (root mean square error of 0.5 mgI/cc) and accurate CT number of VMIs (percentage error of 8.9%) using the PCCT scanner. The overall performance of the PCCT scanner, in terms of iodine quantification and VMI CT number accuracy, was comparable to that of EID-based dual-source, dual-energy scanners.

  18. Sphinx1: Spectrometric Photon Counting and Integration Pixel for X-Ray Imaging With a 100 Electron LSB

    Science.gov (United States)

    Habib, Amr; Arques, Marc; Dupont, Bertrand; Rohr, Pierre; Sicard, Gilles; Tchagaspanian, Michaël; Verger, Loïck

    2015-06-01

    Sphinx1 is a novel pixel architecture adapted for X-ray imaging that can detect radiation by photon counting and by charge integration. In photon counting mode, each photon is compensated by one or more counter-charge packets which can be dimensioned at a level as low as 100 electrons and the number of injected counter-charge packets indicates the incoming photon energy, thus allowing a spectrometric detection. The pixel is also able to detect radiation by integrating the charges deposited by all incoming photons and converting this analog value into a digital data with a least significant bit (LSB) of 100 electrons through the use of the counter-charge concept. In this paper, Sphinx1 pixel architecture is presented with emphasis on the counter-charge design, and the two modes of operation are described in detail. The pixel was simulated using Eldo simulator. Simulation results indicate an equivalent noise charge (ENC) of 48 electrons-rms for a detector capacitance of 75 fF. The LSB linearity and the ENC are further studied for different values of detector capacitances. The analog and digital power consumptions are calculated to be less than 1 μW in static conditions, proving the architecture to be suitable for large area detectors. Finally, corner simulations show a consistent performance against transistors mismatch. Proof of concept test chip of 5 mm × 5 mm. test chip is being designed fabricated in CMOS 0.13 μm technology, with a pixel pitch of 200 μm.

  19. Photon-Counting Kinetic Inductance Detectors (KID) for Far/Mid-Infrared Space Spectroscopy with the Origins Space Telescope (OST)

    Science.gov (United States)

    Noroozian, Omid; Barrentine, Emily M.; Stevenson, Thomas R.; Brown, Ari D.; Moseley, Samuel Harvey; Wollack, Edward; Pontoppidan, Klaus Martin; U-Yen, Konpop; Mikula, Vilem

    2018-01-01

    Photon-counting detectors are highly desirable for reaching the ~ 10-20 W/√Hz power sensitivity permitted by the Origins Space Telescope (OST). We are developing unique Kinetic Inductance Detectors (KIDs) with photon counting capability in the far/mid-IR. Combined with an on-chip far-IR spectrometer onboard OST these detectors will enable a new data set for exploring galaxy evolution and the growth of structure in the Universe. Mid-IR spectroscopic surveys using these detectors will enable mapping the composition of key volatiles in planet-forming material around protoplanetary disks and their evolution into solar systems. While these OST science objectives represent a well-organized community agreement they are impossible to reach without a significant leap forward in detector technology, and the OST is likely not to be recommended if a path to suitable detectors does not exist.To reach the required sensitivity we are experimenting with superconducting resonators made from thin aluminum films on single-crystal silicon substrates. Under the right conditions, small-volume inductors made from these films can become ultra-sensitive to single photons >90 GHz. Understanding the physics of these superconductor-dielectric systems is critical to performance. We achieved a very high quality factor of 0.5 x 106 for a 10-nm Al resonator at n ~ 1 microwave photon drive power, by far the highest value for such thin films in the literature. We measured a residual electron density of 95% efficiency at 0.5 - 1.0 THz is achievable.We report on these developments and discuss plans to test in our facility through funding from our recently awarded ROSES-APRA grant and Roman Technology Fellowship award.

  20. Near-Infrared Photon-Counting Camera for High-Sensitivity Observations

    Science.gov (United States)

    Jurkovic, Michael

    2012-01-01

    The dark current of a transferred-electron photocathode with an InGaAs absorber, responsive over the 0.9-to-1.7- micron range, must be reduced to an ultralow level suitable for low signal spectral astrophysical measurements by lowering the temperature of the sensor incorporating the cathode. However, photocathode quantum efficiency (QE) is known to reduce to zero at such low temperatures. Moreover, it has not been demonstrated that the target dark current can be reached at any temperature using existing photocathodes. Changes in the transferred-electron photocathode epistructure (with an In- GaAs absorber lattice-matched to InP and exhibiting responsivity over the 0.9- to-1.7- m range) and fabrication processes were developed and implemented that resulted in a demonstrated >13x reduction in dark current at -40 C while retaining >95% of the approximately equal to 25% saturated room-temperature QE. Further testing at lower temperature is needed to confirm a >25 C predicted reduction in cooling required to achieve an ultralow dark-current target suitable for faint spectral astronomical observations that are not otherwise possible. This reduction in dark current makes it possible to increase the integration time of the imaging sensor, thus enabling a much higher near-infrared (NIR) sensitivity than is possible with current technology. As a result, extremely faint phenomena and NIR signals emitted from distant celestial objects can be now observed and imaged (such as the dynamics of redshifting galaxies, and spectral measurements on extra-solar planets in search of water and bio-markers) that were not previously possible. In addition, the enhanced NIR sensitivity also directly benefits other NIR imaging applications, including drug and bomb detection, stand-off detection of improvised explosive devices (IED's), Raman spectroscopy and microscopy for life/physical science applications, and semiconductor product defect detection.

  1. On the analogy between pulse-pile-up in energy-sensitive, photon-counting detectors and level-crossing of shot noise

    Science.gov (United States)

    Roessl, Ewald; Bartels, Matthias; Daerr, Heiner; Proksa, Roland

    2016-03-01

    Shot noise processes are omnipresent in physics and many of their properties have been extensively studied in the past, including the particular problem of level crossing of shot noise. Energy-sensitive, photon-counting detectors using comparators to discriminate pulse-heights are currently heavily investigated for medical applications, e.g. for x-ray computed tomography and x-ray mammography. Surprisingly, no mention of the close relation between the two topics can be found in the literature on photon-counting detectors. In this paper, we point out the close analogy between level crossing of shot noise and the problem of determining count rates of photon- counting detectors subject to pulse pile-up. The latter is very relevant for obtaining precise forward models for photon-counting detectors operated under conditions of very high x-ray flux employed in clinical x-ray computed tomography. Although several attempts have been made to provide reasonably accurate, approximative models for the registered number of counts in x-ray detectors under conditions of high flux and arbitrary x-ray spectra, see, e.g., no exact, analytic solution is given in the literature for general continuous pulse shapes. In this paper we present such a solution for arbitrary response functions, x-ray spectra and continuous pulse shapes based on a result from the theory of level crossing. We briefly outline the theory of level crossing including the famous Rice theorem and translate from the language of level crossing to the language of photon-counting detection.

  2. High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large Tunability

    Directory of Open Access Journals (Sweden)

    Andreas Schmitt-Sody

    2008-01-01

    Full Text Available We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (>10% modulation depth and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature.

  3. Zero-Energy Modes from Coalescing Andreev States in a Two-Dimensional Semiconductor-Superconductor Hybrid Platform.

    Science.gov (United States)

    Suominen, H J; Kjaergaard, M; Hamilton, A R; Shabani, J; Palmstrøm, C J; Marcus, C M; Nichele, F

    2017-10-27

    We investigate zero-bias conductance peaks that arise from coalescing subgap Andreev states, consistent with emerging Majorana zero modes, in hybrid semiconductor-superconductor wires defined in a two-dimensional InAs/Al heterostructure using top-down lithography and gating. The measurements indicate a hard superconducting gap, ballistic tunneling contact, and in-plane critical fields up to 3 T. Top-down lithography allows complex geometries, branched structures, and straightforward scaling to multicomponent devices compared to structures made from assembled nanowires.

  4. Detection of secondary electrons with pixelated hybrid semiconductor detectors; Sekundaerelektronennachweis mit pixelierten hybriden Halbleiterdetektoren

    Energy Technology Data Exchange (ETDEWEB)

    Gebert, Ulrike Sonja

    2011-09-14

    Within the scope of this thesis, secondary electrons were detected with a pixelated semiconductor detector named Timepix. The Timepix detector consists of electronics and a sensor made from a semiconductor material. The connection of sensor and electronics is done for each pixel individually using bump bonds. Electrons with energies above 3 keV can be detected with the sensor. One electron produces a certain amount of electron-hole pairs according to its energy. The charge then drifts along an electric field to the pixel electronics, where it induces an electric signal. Even without a sensor it is possible to detect an electric signal from approximately 1000 electrons directly in the pixel electronics. Two different detector systems to detect secondary electrons using the Timepix detector were investigated during this thesis. First of all, a hybrid photon detector (HPD) was used to detect single photoelectrons. The HPD consists of a vacuum vessel with an entrance window and a cesium iodine photocathode at the inner surface of the window. Photoelectrons are released from the photocathode by incident light and are accelerated in an electric field towards the Timepix detector, where the point of interaction and the arrival time of the electron is determined. With a proximity focusing setup, a time resolution of 12 ns (with an acceleration voltage of 20 kV between photocathode and Timepix detector) was obtained. The HPD examined in this thesis showed a strong dependence of the dark rate form the acceleration voltage and the pressure in the vacuum vessel. At a pressure of few 10{sup -5} mbar and an acceleration voltage of 20 kV, the dark rate was about 800 Hz per mm{sup 2} area of the read out photocathode. One possibility to reduce the dark rate is to identify ion feedback events. With a slightly modified setup it was possible to reduce the dark rate to 0.5 Hz/mm{sup 2}. To achieve this, a new photocathode was mounted in a shorter distance to the detector. The

  5. AURORA on MEGSAT 1 a photon counting observatory for the Earth UV night-sky background and Aurora emission

    CERN Document Server

    Monfardini, A; Stalio, R; Mahne, N; Battiston, R; Menichelli, M; Mazzinghi, P

    2001-01-01

    A low-mass, low-cost photon-counting scientific payload has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission with a telescope nicknamed 'Notte' and the Aurora emission with 'Alba'. AURORA, this is the name of the experiment, will determine, with the 'Notte' channel, the overall night-side photon background in the 300-400 nm spectral range, together with a particular 2 sup + N sub 2 line (lambda sub c =337 nm). The 'Alba' channel, on the other hand, will study the Aurora emissions in four different spectral bands (FWHM=8.4-9.6 nm) centered on: 367 nm (continuum evaluation), 391 nm (1 sup - N sup + sub 2), 535 nm (continuum evaluation), 560 nm (OI). The instrument has been launched on the 26 September, 2000 from the Baikonur cosmodrome on a modified SS18 Dnepr-1 'Satan' rocket. The satellite orbit is nearly circular (h sub a sub p sub o sub g sub e sub e =648 km, e=0.0022), and the inclination of the orbital plane is 64.56 deg. An overview of...

  6. High-performance integrated pick-up circuit for SPAD arrays in time-correlated single photon counting

    Science.gov (United States)

    Acconcia, Giulia; Cominelli, Alessandro; Peronio, Pietro; Rech, Ivan; Ghioni, Massimo

    2017-05-01

    The analysis of optical signals by means of Single Photon Avalanche Diodes (SPADs) has been subject to a widespread interest in recent years. The development of multichannel high-performance Time Correlated Single Photon Counting (TCSPC) acquisition systems has undergone a fast trend. Concerning the detector performance, best in class results have been obtained resorting to custom technologies leading also to a strong dependence of the detector timing jitter from the threshold used to determine the onset of the photogenerated current flow. In this scenario, the avalanche current pick-up circuit plays a key role in determining the timing performance of the TCSPC acquisition system, especially with a large array of SPAD detectors because of electrical crosstalk issues. We developed a new current pick-up circuit based on a transimpedance amplifier structure able to extract the timing information from a 50-μm-diameter custom technology SPAD with a state-of-art timing jitter as low as 32ps and suitable to be exploited with SPAD arrays. In this paper we discuss the key features of this structure and we present a new version of the pick-up circuit that also provides quenching capabilities in order to minimize the number of interconnections required, an aspect that becomes more and more crucial in densely integrated systems.

  7. Contrast-enhanced spectral mammography based on a photon-counting detector: quantitative accuracy and radiation dose

    Science.gov (United States)

    Lee, Seungwan; Kang, Sooncheol; Eom, Jisoo

    2017-03-01

    Contrast-enhanced mammography has been used to demonstrate functional information about a breast tumor by injecting contrast agents. However, a conventional technique with a single exposure degrades the efficiency of tumor detection due to structure overlapping. Dual-energy techniques with energy-integrating detectors (EIDs) also cause an increase of radiation dose and an inaccuracy of material decomposition due to the limitations of EIDs. On the other hands, spectral mammography with photon-counting detectors (PCDs) is able to resolve the issues induced by the conventional technique and EIDs using their energy-discrimination capabilities. In this study, the contrast-enhanced spectral mammography based on a PCD was implemented by using a polychromatic dual-energy model, and the proposed technique was compared with the dual-energy technique with an EID in terms of quantitative accuracy and radiation dose. The results showed that the proposed technique improved the quantitative accuracy as well as reduced radiation dose comparing to the dual-energy technique with an EID. The quantitative accuracy of the contrast-enhanced spectral mammography based on a PCD was slightly improved as a function of radiation dose. Therefore, the contrast-enhanced spectral mammography based on a PCD is able to provide useful information for detecting breast tumors and improving diagnostic accuracy.

  8. Improving the counting efficiency in time-correlated single photon counting experiments by dead-time optimization

    Energy Technology Data Exchange (ETDEWEB)

    Peronio, P.; Acconcia, G.; Rech, I.; Ghioni, M. [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2015-11-15

    Time-Correlated Single Photon Counting (TCSPC) has been long recognized as the most sensitive method for fluorescence lifetime measurements, but often requiring “long” data acquisition times. This drawback is related to the limited counting capability of the TCSPC technique, due to pile-up and counting loss effects. In recent years, multi-module TCSPC systems have been introduced to overcome this issue. Splitting the light into several detectors connected to independent TCSPC modules proportionally increases the counting capability. Of course, multi-module operation also increases the system cost and can cause space and power supply problems. In this paper, we propose an alternative approach based on a new detector and processing electronics designed to reduce the overall system dead time, thus enabling efficient photon collection at high excitation rate. We present a fast active quenching circuit for single-photon avalanche diodes which features a minimum dead time of 12.4 ns. We also introduce a new Time-to-Amplitude Converter (TAC) able to attain extra-short dead time thanks to the combination of a scalable array of monolithically integrated TACs and a sequential router. The fast TAC (F-TAC) makes it possible to operate the system towards the upper limit of detector count rate capability (∼80 Mcps) with reduced pile-up losses, addressing one of the historic criticisms of TCSPC. Preliminary measurements on the F-TAC are presented and discussed.

  9. Timepix, a 65k programmable pixel readout chip for arrival time, energy and/or photon counting measurements

    CERN Document Server

    Llopart, X; Campbell, M; Tlustos, L; Wong, W

    2008-01-01

    A novel approach for the readout of a TPC at the future linear collider is to use a CMOS pixel detector combined with some kind of gas gain grid. A first test using the photon counting chip Medipix2 with GEM or Micromegas demonstrated the feasibility of such an approach. Although this experiment demonstrated that single primary electrons could be detected the chip did not provide information on the arrival time of the electron in the sensitive gas volume nor did it give any indication of the quantity of charge detected. The Timepix chip uses an external clock with a frequency of up to 100 MHz as a time reference. Each pixel contains a preamplifier, a discriminator with hysteresis and 4-bit DAC for threshold adjustment, synchronization logic and a 14-bit counter with overflow control. Moreover, each pixel can be independently configured in one of four different modes: masked mode: pixel is off, counting mode: 1-count for each signal over threshold, TOT mode: the counter is incremented continuously as long as t...

  10. Performance of a compact position-sensitive photon counting detector with image charge coupling to an air-side anode

    Science.gov (United States)

    Jagutzki, O.; Czasch, A.; Schössler, S.

    2013-05-01

    We discuss a novel micro-channel plate (MCP) photomultiplier with resistive screen (RS-PMT) as a detection device for space- and time-correlated single photon counting, illustrated by several applications. The photomultiplier tube resembles a standard image intensifier device. However, the rear phosphor screen is replaced by a ceramic "window" with resistive coating. The MCP output is transferred through the ceramic plate to the read-out electrode (on the air side) via capacity-coupling of the image charge. This design allows for an easy reconfiguration of the read-out electrode (e.g. pixel, charge-sharing, cross-strip, delay-line) without breaking the vacuum for optimizing the detector performance towards a certain task. It also eases the design and manufacturing process of such a multi-purpose photomultiplier tube. Temporal and spatial resolutions well below 100 ps and 100 microns, respectively, have been reported at event rates as high as 1 MHz, for up to 40 mm effective detection diameter. In this paper we will discuss several applications like wide-field fluorescence microscopy and dual γ/fast-neutron radiography for air cargo screening and conclude with an outlook on large-area detectors for thermal neutrons based on MCPs.

  11. Towards pH-sensitive imaging of small animals with photon-counting difference diffuse fluorescence tomography

    Science.gov (United States)

    Li, Jiao; Wang, Xin; Yi, Xi; Zhang, Limin; Zhou, Zhongxing; Zhao, Huijuan; Gao, Feng

    2012-09-01

    The importance of cellular pH has been shown clearly in the study of cell activity, pathological feature, and drug metabolism. Monitoring pH changes of living cells and imaging the regions with abnormal pH-values, in vivo, could provide invaluable physiological and pathological information for the research of the cell biology, pharmacokinetics, diagnostics, and therapeutics of certain diseases such as cancer. Naturally, pH-sensitive fluorescence imaging of bulk tissues has been attracting great attentions from the realm of near infrared diffuse fluorescence tomography (DFT). Herein, the feasibility of quantifying pH-induced fluorescence changes in turbid medium is investigated using a continuous-wave difference-DFT technique that is based on the specifically designed computed tomography-analogous photon counting system and the Born normalized difference image reconstruction scheme. We have validated the methodology using two-dimensional imaging experiments on a small-animal-sized phantom, embedding an inclusion with varying pH-values. The results show that the proposed approach can accurately localize the target with a quantitative resolution to pH-sensitive variation of the fluorescent yield, and might provide a promising alternative method of pH-sensitive fluorescence imaging in addition to the fluorescence-lifetime imaging.

  12. Time-Correlated Single-Photon Counting Fluorescence Imaging of Lipid Domains In Raft-Mimicking Giant Unilamellar Vesicles

    Science.gov (United States)

    Clarke, James; Cheng, Kwan; Shindell, Orrin; Wang, Exing

    We have designed and constructed a high-throughput electrofusion chamber and an incubator to fabricate Giant Unilamellar Vesicles (GUVs) consisting of high-melting lipids, low-melting lipids, cholesterol and both ordered and disordered phase sensitive fluorescent probes (DiIC12, dehydroergosterol and BODIPY-Cholesterol). GUVs were formed in a 3 stage pulse sequence electrofusion process with voltages ranging from 50mVpp to 2.2Vpp and frequencies from 5Hz to 10Hz. Steady state and time-correlated single-photon counting (TCSPC) fluorescence lifetime (FLIM) based confocal and/or multi-photon microscopic techniques were used to characterize phase separated lipid domains in GUVs. Confocal imaging measures the probe concentration and the chemical environment of the system. TCSPC techniques determine the chemical environment through the perturbation of fluorescent lifetimes of the probes in the system. The above techniques will be applied to investigate the protein-lipid interactions involving domain formation. Specifically, the mechanisms governing lipid domain formations in the above systems that mimic the lipid rafts in cells will be explored. Murchison Fellowship at Trinity University.

  13. High-speed and low-distortion solution for time-correlated single photon counting measurements: A theoretical analysis

    Science.gov (United States)

    Cominelli, A.; Acconcia, G.; Peronio, P.; Ghioni, M.; Rech, I.

    2017-12-01

    In this paper, we describe a novel solution to increase the speed of Time-Correlated Single Photon Counting (TCSPC) measurements by almost an order of magnitude while providing, in principle, zero distortion regardless of the experimental conditions. Typically, the relatively long dead time associated with the conversion electronics requires a proper tune of the excitation power in order to avoid distortions of the reconstructed waveform due to pileup and counting loss. As a result, the maximum operating rate of a TCSPC channel is now limited between 1% and 5% of the excitation frequency, thus leading to relatively long acquisition times. We show that negligible distortion (below 1%) is guaranteed if the dead time associated with the converter is kept below the dead time of the detector, and at the same time the detector dead time is matched to the duration of the excitation period. In this way, unprecedented high-speed operation is possible. In this paper, we provide a theoretical analysis of the technique, including the main non-idealities which are introduced by a generic physical implementation. The results are supported by both numerical simulations and analytical calculations.

  14. C-band superconductor/semiconductor hybrid field-effect transistor amplifier on a LaAlO3 substrate

    Science.gov (United States)

    Nahra, J. J.; Bhasin, K. B.; Toncich, S. S.; Subramanyam, G.; Kapoor, V. J.

    1992-01-01

    A single-stage C-band superconductor/semiconductor hybrid field-effect transistor amplifier was designed, fabricated, and tested at 77 K. The large area (1 inch x 0.5 inches) high temperature superconducting Tl-Ba-Ca-Cu-O (TBCCO) thin film was rf magnetron sputtered onto a LaAlO3 substrate. The film had a transition temperature of about 92 K after it was patterned and etched. The amplifier showed a gain of 6 dB and a 3 dB bandwidth of 100 MHz centered at 7.9 GHz. An identical gold amplifier circuit was tested at 77 K, and these results are compared with those from the hybrid amplifier.

  15. EXCALIBUR: a small-pixel photon counting area detector for coherent X-ray diffraction - Front-end design, fabrication and characterisation

    Science.gov (United States)

    Marchal, J.; Horswell, I.; Willis, B.; Plackett, R.; Gimenez, E. N.; Spiers, J.; Ballard, D.; Booker, P.; Thompson, J. A.; Gibbons, P.; Burge, S. R.; Nicholls, T.; Lipp, J.; Tartoni, N.

    2013-03-01

    Coherent X-ray diffraction experiments on synchrotron X-ray beamlines require detectors with high spatial resolution and large detection area. The read-out chip developed by the MEDIPIX3 collaboration offers a small pixel size of 55 microns resulting in a very high spatial resolution when coupled to a direct X-ray conversion segmented silicon sensor. MEDIPIX3 assemblies present also the advantages of hybrid pixel detectors working in single photon counting mode: noiseless imaging, large dynamic range, extremely high frame rate. The EXCALIBUR detector is under development for the X-ray Coherence and Imaging Beamline I13 of the Diamond Light Source. This new detector consists of three modules, each with 16 MEDIPIX3 chips which can be read-out at 100 frames per second in continuous mode or 1000 frames per second in burst mode. In each module, the sensor is a large single silicon die covering 2 rows of 8 individual MEDIPIX3 read-out chips and provides a continuous active detection region within a module. Each module includes 1 million solder bumps connecting the 55 microns pixels of the silicon sensor to the 55 microns pixels of the 16 MEDIPIX3 read-out chips. The detection area of the 3-module EXCALIBUR detector is 115 mm × 100 mm with a small 6.8 mm wide inactive region between modules. Each detector module is connected to 2 FPGA read-out boards via a flexi-rigid circuit to allow a fully parallel read-out of the 16 MEDIPIX3 chips. The 6 FPGA read-out boards used in the EXCALIBUR detector are interfaced to 6 computing nodes via 10Gbit/s fibre-optic links to maintain the very high frame-rate capability. The standard suite of EPICS control software is used to operate the detector and to integrate it with the Diamond Light Source beamline software environment. This article describes the design, fabrication and characterisation of the MEDIPIX3-based modules composing the EXCALIBUR detector.

  16. Crafting semiconductor organic-inorganic nanocomposites via placing conjugated polymers in intimate contact with nanocrystals for hybrid solar cells.

    Science.gov (United States)

    Zhao, Lei; Lin, Zhiqun

    2012-08-22

    Semiconductor organic-inorganic hybrid solar cells incorporating conjugated polymers (CPs) and nanocrystals (NCs) offer the potential to deliver efficient energy conversion with low-cost fabrication. The CP-based photovoltaic devices are complimented by an extensive set of advantageous characteristics from CPs and NCs, such as lightweight, flexibility, and solution-processability of CPs, combined with high electron mobility and size-dependent optical properties of NCs. Recent research has witnessed rapid advances in an emerging field of directly tethering CPs on the NC surface to yield an intimately contacted CP-NC nanocomposite possessing a well-defined interface that markedly promotes the dispersion of NCs within the CP matrix, facilitates the photoinduced charge transfer between these two semiconductor components, and provides an effective platform for studying the interfacial charge separation and transport. In this Review, we aim to highlight the recent developments in CP-NC nanocomposite materials, critically examine the viable preparative strategies geared to craft intimate CP-NC nanocomposites and their photovoltaic performance in hybrid solar cells, and finally provide an outlook for future directions of this extraordinarily rich field. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Nanoimprinted Hybrid Metal-Semiconductor Plasmonic Multilayers with Controlled Surface Nano Architecture for Applications in NIR Detectors.

    Science.gov (United States)

    Khosroabadi, Akram A; Gangopadhyay, Palash; Hernandez, Steven; Kim, Kyungjo; Peyghambarian, Nasser; Norwood, Robert A

    2015-08-07

    We present a proof of concept for tunable plasmon resonance frequencies in a core shell nano-architectured hybrid metal-semiconductor multilayer structure, with Ag as the active shell and ITO as the dielectric modulation media. Our method relies on the collective change in the dielectric function within the metal semiconductor interface to control the surface. Here we report fabrication and optical spectroscopy studies of large-area, nanostructured, hybrid silver and indium tin oxide (ITO) structures, with feature sizes below 100 nm and a controlled surface architecture. The optical and electrical properties of these core shell electrodes, including the surface plasmon frequency, can be tuned by suitably changing the order and thickness of the dielectric layers. By varying the dimensions of the nanopillars, the surface plasmon wavelength of the nanopillar Ag can be tuned from 650 to 690 nm. Adding layers of ITO to the structure further shifts the resonance wavelength toward the IR region and, depending on the sequence and thickness of the layers within the structure, we show that such structures can be applied in sensing devices including enhancing silicon as a photodetection material.

  18. Nanoimprinted Hybrid Metal-Semiconductor Plasmonic Multilayers with Controlled Surface Nano Architecture for Applications in NIR Detectors

    Directory of Open Access Journals (Sweden)

    Akram A. Khosroabadi

    2015-08-01

    Full Text Available We present a proof of concept for tunable plasmon resonance frequencies in a core shell nano-architectured hybrid metal-semiconductor multilayer structure, with Ag as the active shell and ITO as the dielectric modulation media. Our method relies on the collective change in the dielectric function within the metal semiconductor interface to control the surface. Here we report fabrication and optical spectroscopy studies of large-area, nanostructured, hybrid silver and indium tin oxide (ITO structures, with feature sizes below 100 nm and a controlled surface architecture. The optical and electrical properties of these core shell electrodes, including the surface plasmon frequency, can be tuned by suitably changing the order and thickness of the dielectric layers. By varying the dimensions of the nanopillars, the surface plasmon wavelength of the nanopillar Ag can be tuned from 650 to 690 nm. Adding layers of ITO to the structure further shifts the resonance wavelength toward the IR region and, depending on the sequence and thickness of the layers within the structure, we show that such structures can be applied in sensing devices including enhancing silicon as a photodetection material.

  19. Realizing semiconductor-half-metal transition in zigzag graphene nanoribbons supported on hybrid fluorographene-graphane nanoribbons.

    Science.gov (United States)

    Tang, Shaobin; Cao, Xinrui

    2014-11-14

    Hydrogenation and fluorination provide promising applications for tuning the properties of graphene-based nanomaterials. Using first-principles calculations, we investigate the electronic and magnetic properties of zigzag graphene nanoribbons (ZGNRs) supported on hydrogenated and fluorinated ZGNRs. Our results indicate that the support of zigzag graphane nanoribbon with its full width has less impact on the electronic and magnetic properties of ZGNRs, whereas the ZGNRs supported on fluorographene nanoribbons can be tuned to metal with almost degenerated ferro- and anti-ferromagnetic states due to the intrinsic polarization of substrate. The ZGNRs supported on zigzag hybrid fluorographene-graphane nanoribbons are spin-polarized half-semiconductors with distinct band gaps for spin-up and spin-down channels. Interestingly, in the absence of an external electric field, the spin-polarized band gaps of supported ZGNRs can be well modulated in the opposite direction by changing the ratio of fluorination to hydrogenation concentration in hybrid substrates. Furthermore, the ZGNRs supported on hybrid nanoribbons exhibit the half-semiconducting to half-metallic behavior transition as the interlayer spacing is gradually reduced, which is realized more easily for the hybrid support with a relatively wide fluorographene moiety compared to its narrow counterpart. Present results provide a novel way for designing substrate-supported graphene spintronic devices.

  20. Multiway study of hybridization in nanoscale semiconductor labeled DNA based on fluorescence resonance energy transfer

    DEFF Research Database (Denmark)

    Gholami, Somayeh; Kompany Zare, Mohsen

    2013-01-01

    hybridization in sandwiched nanoassemblies. A multi-equilibria model was properly fitted to the data and confirmed there is a competition between ternary and binary complex formation. Equilibrium constants of DNA hybridization in sandwiched nanoassemblies were estimated for the first time. Equilibrium constants...... illustrated that the extent of hybridization in one side on the target strand depends on hybridization conditions on the other side of the strand. Effects of guanine (G) and cytosine (C) contents of strands on the extent and rate of hybridization were investigated. In addition to equilibrium constants...

  1. Reduction of metal artifact in single photon-counting computed tomography by spectral-driven iterative reconstruction technique.

    Directory of Open Access Journals (Sweden)

    Radin A Nasirudin

    Full Text Available The exciting prospect of Spectral CT (SCT using photon-counting detectors (PCD will lead to new techniques in computed tomography (CT that take advantage of the additional spectral information provided. We introduce a method to reduce metal artifact in X-ray tomography by incorporating knowledge obtained from SCT into a statistical iterative reconstruction scheme. We call our method Spectral-driven Iterative Reconstruction (SPIR.The proposed algorithm consists of two main components: material decomposition and penalized maximum likelihood iterative reconstruction. In this study, the spectral data acquisitions with an energy-resolving PCD were simulated using a Monte-Carlo simulator based on EGSnrc C++ class library. A jaw phantom with a dental implant made of gold was used as an object in this study. A total of three dental implant shapes were simulated separately to test the influence of prior knowledge on the overall performance of the algorithm. The generated projection data was first decomposed into three basis functions: photoelectric absorption, Compton scattering and attenuation of gold. A pseudo-monochromatic sinogram was calculated and used as input in the reconstruction, while the spatial information of the gold implant was used as a prior. The results from the algorithm were assessed and benchmarked with state-of-the-art reconstruction methods.Decomposition results illustrate that gold implant of any shape can be distinguished from other components of the phantom. Additionally, the result from the penalized maximum likelihood iterative reconstruction shows that artifacts are significantly reduced in SPIR reconstructed slices in comparison to other known techniques, while at the same time details around the implant are preserved. Quantitatively, the SPIR algorithm best reflects the true attenuation value in comparison to other algorithms.It is demonstrated that the combination of the additional information from Spectral CT and

  2. Optimized design of a TOF laser range finder based on time-correlated single-photon counting

    Science.gov (United States)

    Wang, Huanqin; Yang, Yixin; Huang, Zhe; Cao, YangYang; Gui, Huaqiao

    2014-11-01

    A time-of-flight (TOF) laser range finder based on time-correlated single photon counting (TCSPC) has been developed. By using a Geiger-mode avalanche photodiode (G-APD) with the ability of detecting single-photon events and Time-to-Digital Converter (TDC) with picosecond resolution, a good linearity with 4.5 cm range precision can be achieved in the range of 1-10 m. This paper highlights a significant advance in improving the key parameters of this system, including the range precision and measurement dynamic range. In our experiments, it was found that both of the precision and the measurement dynamic range were limited by the signal to noise rate (SNR) and the inherent jitter of system. The range precision can be improved by enhancing the SNR of system. However, when the SNR is high enough, the main factors affecting the range precision will turn into the inherent jitter, which makes the range precision can not be improved infinitely. Moreover, the inherent jitter generated by pulsed laser and the signal processing module has been measured, and its influence on the system performance has also been discussed. Taking all of these factors into account, some optimized designs have been proposed to improve range precision and dynamic range simultaneously. The final experiment results show that, after all of these optimization designs, the range precision of system is better than 1.2 cm and the measurement dynamic range is enlarged to 54 m when the sampling time is as short as 1 ms, which is sufficient for many applications of 3D object recognition, computer vision, reverse engineering and virtual reality.

  3. Signal and noise characteristics of a CdTe-based photon counting detector: cascaded systems analysis and experimental studies

    Science.gov (United States)

    Ji, Xu; Zhang, Ran; Ge, Yongshuai; Chen, Guang-Hong; Li, Ke

    2017-03-01

    Recent advances in single photon counting detectors (PCDs) are opening up new opportunities in medical imaging. However, the performance of PCDs is not flawless. Problems such as charge sharing may deteriorate the performance of PCD. This work studied the dependence of the signal and noise properties of a cadmium telluride (CdTe)-based PCD on the charge sharing effect and the anti-charge sharing (ACS) capability offered by the PCD. Through both serial and parallel cascaded systems analysis, a theoretical model was developed to trace the origin of charge sharing in CdTe-based PCD, which is primarily related to remote k-fluorescence re-absorption and spatial spreading of charge cloud. The ACS process was modeled as a sub-imaging state prior to the energy thresholding stage, and its impact on the noise power spectrum (NPS) of PCD can be qualitatively determined by the theoretical model. To validate the theoretical model, experimental studies with a CdTe-based PCD system (XC-FLITE X1, XCounter AB) was performed. Two x-ray radiation conditions, including an RQA-5 beam and a 40 kVp beam, were used for the NPS measurements. Both theoretical predictions and experimental results showed that ACS makes the NPS of the CdTe-based PCD flatter, which corresponds to reduced noise correlation length. The flatness of the NPS is further boosted by increasing the energy threshold or reducing the x-ray energy, both of which reduce the likelihood of registering multiple counts from the same incidenting x-ray photon.

  4. Plasmonic-exciton coupling in synthesized metal/semiconductor hybrid nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Gadalla, A.; Hamad, D. A. [Physics Department, Assiut University, Assiut (Egypt); Mohamed, M. B. [National Institute of Laser Enhanced science (NIELS), Cairo University, Cairo (Egypt)

    2015-12-31

    A new method has been developed to grow plasmonic semiconductor nanocomposites of Au/CdSe and Ag/CdSe. Their chemical composition and crystal structure are determined by X-ray diffraction. The collective optical properties of the prepared semiconductor nanohybrid have been measured using spectrophotometer techniques and compared to those of the individual components. The electron transfer processes from CdSe to the gold are faster than that of the silver. Au/CdSe has a strong plasmonic-excitonic coupling, but Ag/CdSe has a weak plasmonic-excitonic coupling.

  5. FPGA-based photon-counting phase-modulation fluorometer and a brief comparison with that operated in a pulsed-excitation mode

    Science.gov (United States)

    Iwata, Tetsuo; Taga, Takanori; Mizuno, Takahiko

    2017-12-01

    We have constructed a high-efficiency, photon-counting phase-modulation fluorometer (PC-PMF) using a field-programmable gate array, which is a modified version of the photon-counting fluorometer (PCF) that works in a pulsed-excitation mode (Iwata and Mizuno in Meas Sci Technol 28:075501, 2017). The common working principle for both is the simultaneous detection of the photoelectron pulse train, which covers 64 ns with a 1.0-ns resolution time (1.0 ns/channel). The signal-gathering efficiency was improved more than 100 times over that of conventional time-correlated single-photon-counting at the expense of resolution time depending on the number of channels. The system dead time for building a histogram was eliminated, markedly shortening the measurement time for fluorescent samples with moderately high quantum yields. We describe the PC-PMF and make a brief comparison with the pulsed-excitation PCF in precision, demonstrating the potential advantage of PC-PMF.

  6. Every photon counts: improving low, mid, and high-spatial frequency errors on astronomical optics and materials with MRF

    Science.gov (United States)

    Maloney, Chris; Lormeau, Jean Pierre; Dumas, Paul

    2016-07-01

    Many astronomical sensing applications operate in low-light conditions; for these applications every photon counts. Controlling mid-spatial frequencies and surface roughness on astronomical optics are critical for mitigating scattering effects such as flare and energy loss. By improving these two frequency regimes higher contrast images can be collected with improved efficiency. Classically, Magnetorheological Finishing (MRF) has offered an optical fabrication technique to correct low order errors as well has quilting/print-through errors left over in light-weighted optics from conventional polishing techniques. MRF is a deterministic, sub-aperture polishing process that has been used to improve figure on an ever expanding assortment of optical geometries, such as planos, spheres, on and off axis aspheres, primary mirrors and freeform optics. Precision optics are routinely manufactured by this technology with sizes ranging from 5-2,000mm in diameter. MRF can be used for form corrections; turning a sphere into an asphere or free form, but more commonly for figure corrections achieving figure errors as low as 1nm RMS while using careful metrology setups. Recent advancements in MRF technology have improved the polishing performance expected for astronomical optics in low, mid and high spatial frequency regimes. Deterministic figure correction with MRF is compatible with most materials, including some recent examples on Silicon Carbide and RSA905 Aluminum. MRF also has the ability to produce `perfectly-bad' compensating surfaces, which may be used to compensate for measured or modeled optical deformation from sources such as gravity or mounting. In addition, recent advances in MRF technology allow for corrections of mid-spatial wavelengths as small as 1mm simultaneously with form error correction. Efficient midspatial frequency corrections make use of optimized process conditions including raster polishing in combination with a small tool size. Furthermore, a novel MRF

  7. Performance Characterization of Airborne Photon-counting Laser Altimetry in Preparation for ICESat-2 On-orbit Validation.

    Science.gov (United States)

    Magruder, L. A.; Brunt, K. M.

    2016-12-01

    MABEL, (the Multiple Altimeter Beam Experimental Lidar), was created as an airborne engineering model for the instrument onboard the Ice, Cloud and land Elevation Satellite-2 (ICESat-2). Essentially, MABEL was to provide a demonstration of the altimeter measurement strategy, and provide the critical test data needed for ICESat-2 geophysical data product algorithm development. The impact of the MABEL test data is significant in terms of mission preparation, not only for the tasks listed previously but also for the need to examine and establish on-orbit plans for validation of the mission measurements and how they are used to produce higher level products using the geolocated signal. Direct comparison of proxy ICESat-2 elevation data and ground-based GPS data can provide a robust assessment of instrument bias and surface precision. Often this could be done for multiple beams over the same surface and, for MABEL, for various flights within a field campaign. The results throughout MABEL's development provide insight as to overall instrument error and stability. The use of corner cube retro-reflectors (CCR) as ground based fiducials (ground truth) has been proven to be an effective technique for in situ validation of satellite laser altimetry geolocation and ranging in the past. However, given the photon counting technology on-board ICESat-2 there remained question if similar application would be relevant and useful. MABEL test flights over calibration sites containing CCR arrays were collected and analyzed to determine the feasibility of using the technique during the ICESat-2 mission. The results indicate that the CCR signatures allow for an independent geolocation assessment of the altimeter in addition to providing statistical measure of precision and ranging accuracy. Further analysis indicates the utility of these signatures for observability of the geolocation process at a higher resolution than the input data streams (precision orbit determination and precision

  8. Hybrid organic-inorganic semiconductor transducer for optical and electrical sensing

    Science.gov (United States)

    Calio, A.; Cassinese, A.; Casalino, M.; Politi, J.; Barra, M.; De Stefano, L.

    2015-05-01

    Porous silicon (PSi) non-symmetric multilayers are modified by organic molecular beam deposition of an organic semiconductor, namely the N,N'-1H,1H-perfluorobutyldicyanoperylene-carboxydi-imide (PDIF-CN2). Joule evaporation of PDIF-CN2 into the PSi sponge-like matrix not only improves but also adds transducing skills, making this solid-state device a dual (optical and electrical) signal sensor for biochemical monitoring. PDIF-CN2 modified PSi optical microcavities show an increase of about 5 orders of magnitude in electric current with respect to the same bare device. This feature can be used to sense volatile substances.

  9. Active pixel and photon counting imagers based on poly-Si TFTs: rewriting the rule book on large area flat panel x-ray devices

    Science.gov (United States)

    Antonuk, Larry E.; Koniczek, Martin; El-Mohri, Youcef; Zhao, Qihua

    2009-02-01

    The near-ubiquity of large area, active matrix, flat-panel imagers (AMFPIs) in medical x-ray imaging applications is a testament to the usefulness and adaptability of the relatively simple concept of array pixels based on a single amorphous silicon (a-Si:H) TFT coupled to a pixel storage capacitor. Interestingly, the fundamental advantages of a-Si:H thin film electronics (including compatibility with very large area processing, high radiation damage resistance, and continued development driven by interest in mainstream consumer products) are shared by the rapidly advancing technology of polycrystalline silicon (poly-Si) TFTs. Moreover, the far higher mobilities of poly-Si TFTs, compared to those of a- Si:H, facilitate the creation of faster and more complex circuits than are possible with a-Si:H TFTs, leading to the possibility of new classes of large area, flat panel imagers. Given recent progress in the development of initial poly-Si imager prototypes, the creation of increasingly sophisticated active pixel arrays offering pixel-level amplification, variable gain, very high frame rates, and excellent signal-to-noise performance under all fluoroscopic and radiographic conditions (including very low exposures and high spatial frequencies), appears within reach. In addition, it is conceivable that the properties of poly-Si TFTs could allow the development of large area imagers providing single xray photon counting capabilities. In this article, the factors driving the possible realization of clinically practical active pixel and photon counting imagers based on poly-Si TFTs are described and simple calculational estimates related to photon counting imagers are presented. Finally, the prospect for future development of such imagers is discussed.

  10. Ideal-observer detectability in photon-counting differential phase-contrast imaging using a linear-systems approach

    Energy Technology Data Exchange (ETDEWEB)

    Fredenberg, Erik; Danielsson, Mats; Stayman, J. Webster; Siewerdsen, Jeffrey H.; Aslund, Magnus [Research and Development, Philips Women' s Healthcare, Smidesvaegen 5, SE-171 41 Solna, Sweden and Department of Physics, Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm (Sweden); Department of Physics, Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm (Sweden); Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Department of Biomedical Engineering and Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Research and Development, Philips Women' s Healthcare, Smidesvaegen 5, SE-171 41 Solna (Sweden)

    2012-09-15

    Purpose: To provide a cascaded-systems framework based on the noise-power spectrum (NPS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) for quantitative evaluation of differential phase-contrast imaging (Talbot interferometry) in relation to conventional absorption contrast under equal-dose, equal-geometry, and, to some extent, equal-photon-economy constraints. The focus is a geometry for photon-counting mammography. Methods: Phase-contrast imaging is a promising technology that may emerge as an alternative or adjunct to conventional absorption contrast. In particular, phase contrast may increase the signal-difference-to-noise ratio compared to absorption contrast because the difference in phase shift between soft-tissue structures is often substantially larger than the absorption difference. We have developed a comprehensive cascaded-systems framework to investigate Talbot interferometry, which is a technique for differential phase-contrast imaging. Analytical expressions for the MTF and NPS were derived to calculate the NEQ and a task-specific ideal-observer detectability index under assumptions of linearity and shift invariance. Talbot interferometry was compared to absorption contrast at equal dose, and using either a plane wave or a spherical wave in a conceivable mammography geometry. The impact of source size and spectrum bandwidth was included in the framework, and the trade-off with photon economy was investigated in some detail. Wave-propagation simulations were used to verify the analytical expressions and to generate example images. Results: Talbot interferometry inherently detects the differential of the phase, which led to a maximum in NEQ at high spatial frequencies, whereas the absorption-contrast NEQ decreased monotonically with frequency. Further, phase contrast detects differences in density rather than atomic number, and the optimal imaging energy was found to be a factor of 1.7 higher than for absorption

  11. A neural network-based method for spectral distortion correction in photon counting x-ray CT

    Science.gov (United States)

    Touch, Mengheng; Clark, Darin P.; Barber, William; Badea, Cristian T.

    2016-08-01

    Spectral CT using a photon counting x-ray detector (PCXD) shows great potential for measuring material composition based on energy dependent x-ray attenuation. Spectral CT is especially suited for imaging with K-edge contrast agents to address the otherwise limited contrast in soft tissues. We have developed a micro-CT system based on a PCXD. This system enables both 4 energy bins acquisition, as well as full-spectrum mode in which the energy thresholds of the PCXD are swept to sample the full energy spectrum for each detector element and projection angle. Measurements provided by the PCXD, however, are distorted due to undesirable physical effects in the detector and can be very noisy due to photon starvation in narrow energy bins. To address spectral distortions, we propose and demonstrate a novel artificial neural network (ANN)-based spectral distortion correction mechanism, which learns to undo the distortion in spectral CT, resulting in improved material decomposition accuracy. To address noise, post-reconstruction denoising based on bilateral filtration, which jointly enforces intensity gradient sparsity between spectral samples, is used to further improve the robustness of ANN training and material decomposition accuracy. Our ANN-based distortion correction method is calibrated using 3D-printed phantoms and a model of our spectral CT system. To enable realistic simulations and validation of our method, we first modeled the spectral distortions using experimental data acquired from 109Cd and 133Ba radioactive sources measured with our PCXD. Next, we trained an ANN to learn the relationship between the distorted spectral CT projections and the ideal, distortion-free projections in a calibration step. This required knowledge of the ground truth, distortion-free spectral CT projections, which were obtained by simulating a spectral CT scan of the digital version of a 3D-printed phantom. Once the training was completed, the trained ANN was used to perform

  12. Photon counting x-ray imaging with K-edge filtered x-rays: A simulation study.

    Science.gov (United States)

    Atak, Haluk; Shikhaliev, Polad M

    2016-03-01

    In photon counting (PC) x-ray imaging and computed tomography (CT), the broad x-ray spectrum can be split into two parts using an x-ray filter with appropriate K-edge energy, which can improve material decomposition. Recent experimental study has demonstrated substantial improvement in material decomposition with PC CT when K-edge filtered x-rays were used. The purpose of the current work was to conduct further investigations of the K-edge filtration method using comprehensive simulation studies. The study was performed in the following aspects: (1) optimization of the K-edge filter for a particular imaging configuration, (2) effects of the K-edge filter parameters on material decomposition, (3) trade-off between the energy bin separation, tube load, and beam quality with K-edge filter, (4) image quality of general (unsubtracted) images when a K-edge filter is used to improve dual energy (DE) subtracted images, and (5) improvements with K-edge filtered x-rays when PC detector has limited energy resolution. The PC x-ray images of soft tissue phantoms with 15 and 30 cm thicknesses including iodine, CaCO3, and soft tissue contrast materials, were simulated. The signal to noise ratio (SNR) of the contrast elements was determined in general and material-decomposed images using K-edge filters with different atomic numbers and thicknesses. The effect of the filter atomic number and filter thickness on energy separation factor and SNR was determined. The boundary conditions for the tube load and halfvalue layer were determined when the K-edge filters are used. The material-decomposed images were also simulated using PC detector with limited energy resolution, and improvements with K-edge filtered x-rays were quantified. The K-edge filters with atomic numbers from 56 to 71 and K-edge energies 37.4-63.4 keV, respectively, can be used for tube voltages from 60 to 150 kVp, respectively. For a particular tube voltage of 120 kVp, the Gd and Ho were the optimal filter materials

  13. Effects of calibration methods on quantitative material decomposition in photon-counting spectral computed tomography using a maximum a posteriori estimator.

    Science.gov (United States)

    Curtis, Tyler E; Roeder, Ryan K

    2017-10-01

    Advances in photon-counting detectors have enabled quantitative material decomposition using multi-energy or spectral computed tomography (CT). Supervised methods for material decomposition utilize an estimated attenuation for each material of interest at each photon energy level, which must be calibrated based upon calculated or measured values for known compositions. Measurements using a calibration phantom can advantageously account for system-specific noise, but the effect of calibration methods on the material basis matrix and subsequent quantitative material decomposition has not been experimentally investigated. Therefore, the objective of this study was to investigate the influence of the range and number of contrast agent concentrations within a modular calibration phantom on the accuracy of quantitative material decomposition in the image domain. Gadolinium was chosen as a model contrast agent in imaging phantoms, which also contained bone tissue and water as negative controls. The maximum gadolinium concentration (30, 60, and 90 mM) and total number of concentrations (2, 4, and 7) were independently varied to systematically investigate effects of the material basis matrix and scaling factor calibration on the quantitative (root mean squared error, RMSE) and spatial (sensitivity and specificity) accuracy of material decomposition. Images of calibration and sample phantoms were acquired using a commercially available photon-counting spectral micro-CT system with five energy bins selected to normalize photon counts and leverage the contrast agent k-edge. Material decomposition of gadolinium, calcium, and water was performed for each calibration method using a maximum a posteriori estimator. Both the quantitative and spatial accuracy of material decomposition were most improved by using an increased maximum gadolinium concentration (range) in the basis matrix calibration; the effects of using a greater number of concentrations were relatively small in

  14. High Throughput, High Yield Fabrication of High Quantum Efficiency Back-Illuminated Photon Counting, Far UV, UV, and Visible Detector Arrays

    Science.gov (United States)

    Nikzad, Shouleh; Hoenk, M. E.; Carver, A. G.; Jones, T. J.; Greer, F.; Hamden, E.; Goodsall, T.

    2013-01-01

    In this paper we discuss the high throughput end-to-end post fabrication processing of high performance delta-doped and superlattice-doped silicon imagers for UV, visible, and NIR applications. As an example, we present our results on far ultraviolet and ultraviolet quantum efficiency (QE) in a photon counting, detector array. We have improved the QE by nearly an order of magnitude over microchannel plates (MCPs) that are the state-of-the-art UV detectors for many NASA space missions as well as defense applications. These achievements are made possible by precision interface band engineering of Molecular Beam Epitaxy (MBE) and Atomic Layer Deposition (ALD).

  15. Future semiconductor detectors using advanced microelectronics with post-processing, hybridization and packaging technology

    CERN Document Server

    Heijne, Erik H M

    2005-01-01

    Several challenges for tracking with semiconductor detectors in the high rate environment of future elementary particle physics experiments are discussed, such as reduction of spurious hits and ambiguities and identification of short-lived 'messenger' particles inside jets. To meet these requirements the instrumentation increasingly calls on progress in microelectronics. Advanced silicon integration technology for 3D packaging now offers post-processing of CMOS such as wafer thinning to 50µm and through-wafer vias of <10µm. These technologies might be applied to create new tracking detectors which can handle vertexing under the difficult rate conditions. The sensor layers can be only ~50µm thick with low noise performance and better radiation hardness by using small volume pixels. Multi-layer sensors with integrated coincidence signal processing could discriminate real tracks from various sources of background. Even in a ~400µm thick 3D assembly the vectors of tracks can be determined in ~10 degree bin...

  16. Single-Step Multicolor Fluorescence In Situ Hybridization Using Semiconductor Quantum Dot–DNA Conjugates

    Science.gov (United States)

    Bentolila, Laurent A.; Weiss, Shimon

    2011-01-01

    We report a rapid method for the direct multicolor imaging of multiple subnuclear genetic sequences using novel quantum dot-based fluorescence in situ hybridization (FISH) probes (QD–FISH). Short DNA oligonucleotides were attached on QDs and used in a single hybridization/detection step of target sites in situ. QD–FISH probes penetrate both intact interphase nuclei and metaphase chromosomes and showed good targeting of dense chromatin domains with minimal steric hindrances. We further demonstrated that QD’s broad absorption spectra allowed different colored probes specific for distinct subnuclear genetic sequences to be simultaneously excited with a single excitation wavelength and imaged free of chromatic aberrations in a single exposure. Thus, these results demonstrate that QD–FISH probes are very effective in multicolor FISH applications. This work also documents new possibilities of using QD–FISH probes detection down to the single molecule level. PMID:16679564

  17. Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface

    KAUST Repository

    Gruenewald, Marco

    2015-02-11

    We investigate the prototypical hybrid interface formed between PTCDA and conductive n-doped ZnO films by means of complementary optical and electronic spectroscopic techniques. We demonstrate that shallow donors in the vicinity of the ZnO surface cause an integer charge transfer to PTCDA, which is clearly restricted to the first monolayer. By means of DFT calculations, we show that the experimental signatures of the anionic PTCDA species can be understood in terms of strong hybridization with localized states (the shallow donors) in the substrate and charge back-donation, resulting in an effectively integer charge transfer across the interface. Charge transfer is thus not merely a question of locating the Fermi level above the PTCDA electron-transport level but requires rather an atomistic understanding of the interfacial interactions. The study reveals that defect sites and dopants can have a significant influence on the specifics of interfacial coupling and thus on carrier injection or extraction.

  18. Si nanowires organic semiconductor hybrid heterojunction solar cells toward 10% efficiency.

    Science.gov (United States)

    He, Lining; Jiang, Changyun; Wang, Hao; Lai, Donny; Rusli

    2012-03-01

    High-efficiency hybrid solar cells are fabricated using a simple approach of spin coating a transparent hole transporting organic small molecule, 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-OMeTAD) on silicon nanowires (SiNWs) arrays prepared by electroless chemical etching. The characteristics of the hybrid cells are investigated as a function of SiNWs length from 0.15 to 5 μm. A maximum average power conversion efficiency of 9.92% has been achieved from 0.35 μm length SiNWs cells, despite a 12% shadowing loss and the absence of antireflective coating and back surface field enhancement. It is found that enhanced aggregations in longer SiNWs limit the cell performance due to increased series resistance and higher carrier recombination in the shorter wavelength region. The effects of the Si substrate doping concentrations on the performance of the cells are also investigated. Cells with higher substrate doping concentration exhibit a significant drop in the incident photons-to-current conversion efficiency (IPCE) in the near infrared region. Nevertheless, a promising short circuit current density of 19 mA/cm(2) and IPCE peak of 57% have been achieved for a 0.9 μm length SiNWs cell fabricated on a highly doped substrate with a minority-carrier diffusion length of only 15 μm. The results suggest that such hybrid cells can potentially be realized using Si thin films instead of bulk substrates. This is promising towards realizing low-cost and high-efficiency SiNWs/organic hybrid solar cells. © 2012 American Chemical Society

  19. Super-resolving quantum lidar: entangled coherent-state sources with binary-outcome photon counting measurement suffice to beat the shot-noise limit.

    Science.gov (United States)

    Wang, Qiang; Hao, Lili; Zhang, Yong; Xu, Lu; Yang, Chenghua; Yang, Xu; Zhao, Yuan

    2016-03-07

    We investigate the performance of the super-resolving quantum lidar with the entangled coherent states of light in the presence of loss and noise, especially in the noisy case. An exact analytical expression of the output signal has been derived with the binary-outcome photon counting measurements. Numerical results show that the resolution of our scheme with parity detection is √N (N) times enhanced relative to that of the coherent-state strategy with the same (intensity) detection in the lossless and noiseless cases. The influences of phase diffusion on resolution and sensitivity have been analyzed and discussed. It is found that the super-resolution emerges in the whole diffusion rate regions, whereas the super-sensitivity just exists in the high and low diffusion rate regimes. Comparisons are made with the well known N00N states, the results show that the entangled coherent states performs better resolution and sensitivity than those of the N00N scheme in the whole diffusion regimes. In addition, the effects of photon loss on resolution and sensitivity have also been studied. The phase sensitivity can beat the shot noise limit and the resolution is much better than the Rayleigh diffraction limit in the whole loss regions. Finally, the zero-nonzero photon counting measurement gives much worse sensitivity than that of the parity detection, which is just opposite from the case as demonstrated in a recent coherent-light Mach-Zehnder experiment.

  20. Enhanced discrimination of calcified and soft arterial plaques using computed tomography with a multi-energy-window photon counting x-ray detector

    Science.gov (United States)

    Wang, Xiaolan; Xu, Jingyan; Taguchi, Katsuyuki; Patt, Bradley E.; Wagenaar, Douglas J.; Frey, Eric C.

    2009-02-01

    This work aims at discriminating between soft and calcified coronary artery plaques using microCT with a multi-energywindow photon counting X-ray detector (PCXD). We have previously investigated a solid state X-ray detector which has the capability to count individual photons in different energy windows. The data from these energy windows may be treated as multiple simultaneous X-ray acquisitions within non-overlapping energy windows that can provide additional information about tissue differences. In this work, we simulated a photon counting detector with five energy windows. We investigated two approaches for using the energy information provided by this detector. First, we applied energy weighting to the reconstruction from different energy windows to improve the signal-to-noise ratio between calcified and soft plaques. This resulted in a significant improvement in the signal-to-noise ratio. Second, we applied the basis material decomposition method to discriminate coronary artery plaques based on their calcium content. The results were compared with those obtained using dual-kVp material decomposition. We observed significantly improved contrast-tonoise ratios for the PCXD-based approaches.

  1. Modeling energy band gap of doped TiO2 semiconductor using homogeneously hybridized support vector regression with gravitational search algorithm hyper-parameter optimization

    Science.gov (United States)

    Owolabi, Taoreed O.; Akande, Kabiru O.; Olatunji, Sunday O.; Aldhafferi, Nahier; Alqahtani, Abdullah

    2017-11-01

    Titanium dioxide (TiO2) semiconductor is characterized with a wide band gap and attracts a significant attention for several applications that include solar cell carrier transportation and photo-catalysis. The tunable band gap of this semiconductor coupled with low cost, chemical stability and non-toxicity make it indispensable for these applications. Structural distortion always accompany TiO2 band gap tuning through doping and this present work utilizes the resulting structural lattice distortion to estimate band gap of doped TiO2 using support vector regression (SVR) coupled with novel gravitational search algorithm (GSA) for hyper-parameters optimization. In order to fully capture the non-linear relationship between lattice distortion and band gap, two SVR models were homogeneously hybridized and were subsequently optimized using GSA. GSA-HSVR (hybridized SVR) performs better than GSA-SVR model with performance improvement of 57.2% on the basis of root means square error reduction of the testing dataset. Effect of Co doping and Nitrogen-Iodine co-doping on band gap of TiO2 semiconductor was modeled and simulated. The obtained band gap estimates show excellent agreement with the values reported from the experiment. By implementing the models, band gap of doped TiO2 can be estimated with high level of precision and absorption ability of the semiconductor can be extended to visible region of the spectrum for improved properties and efficiency.

  2. Simulation and optimization of optical performance of time-delay-integration complementary metal-oxide-semiconductor image sensor based on hybrid charge-digital accumulation architecture

    Science.gov (United States)

    Gao, Jing; Huang, Rui; Nie, Kaiming; Xu, Jiangtao; Li, Yi

    2017-08-01

    An analytical model of hybrid accumulation architecture based on charge-domain and digital-domain time-delay-integration complementary metal-oxide-semiconductor image sensor (TDI-CIS) in the scanning direction is proposed. Optical performance of signal-noise-ratio, dynamic range, and modulation transfer function of the charge-domain, digital-domain, and hybrid accumulation scheme is simulated and analyzed. The synthetical evaluation target (SET) is defined to obtain the best performance under different distribution methods of the charge-domain and digital-domain at a fixed TDI stage for a hybrid accumulation scheme. According to the simulation results, the hybrid accumulation scheme whose charge-domain accumulation stage is 8 and digital-domain accumulation stage is 16 has the optimal SET, which is 12.99% higher than a 128-stage digital-domain accumulation scheme and 25% higher than the 128-stage charge-domain accumulation scheme.

  3. Influence of Semiconductor Nanocrystal Concentration on Polymer Hole Transport in Hybrid Nanocomposites

    OpenAIRE

    Ryan Pate; Adrienne D. Stiff-Roberts

    2012-01-01

    This article investigates hole transport in poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV)/CdSe colloidal quantum dot (CQD) nanocomposites using a modified time-of-flight photoconductivity technique. The measured hole drift mobilities are analyzed in the context of Bässler’s Gaussian disorder model and the correlated disorder model in order to determine the polymer internal morphology of hybrid nanocomposite thin films. This work shows that increasing the CdSe CQD...

  4. Chlorine gas sensors using hybrid organic semiconductors of PANI/ZnPcCl{sub 16}

    Energy Technology Data Exchange (ETDEWEB)

    Lei Tingping; Lue Wenlong; Liu Yang; Tao Wei; Sun Daoheng [College of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005 (China); Shi Yunbo; Wang Liquan [Mechanical Engineering Center for Post-doctoral Studies, Harbin Engineering University, Harbin 150001 (China); Yuan Pengliang [Qingyang Secondary Specialized School of Science and Technology, Qingyang 745000 (China); Lin Liwei, E-mail: shiyunbo@126.co, E-mail: sundh@xmu.edu.c [Department of Mechanical Engineering and Berkeley Sensor and Actuator Center, University of California, Berkeley, California 94720 (United States)

    2010-08-15

    PANI/ZnPcCl{sub 16} (polyaniline doped with sulfosalicylic acid/hexadecachloro zinc phthalocyanine) powders were vacuum co-deposited onto Si substrates, where Pt interdigitated electrodes were made by micromachining. The PANI/ZnPcCl{sub 16} films were characterized and analyzed by SEM, and the influencing factors on its intrinsic performance were analyzed and sensitivities of the sensors were investigated by exposure to chlorine (Cl{sub 2}) gas. The results showed that powders prepared with a stoichiometric ratio of (ZnPcCl{sub 16}){sub 0.6}(PANI){sub 0.4} had a preferential sensitivity to Cl{sub 2} gas, superior to those prepared otherwise; the optimal vacuum co-deposition conditions for the films are a substrate temperature of 160 {sup 0}C, an evaporation temperature of 425 {sup 0}C and a film thickness of 75 nm; elevating the operation temperature (above 100 {sup 0}C) or increasing the gas concentration (over 100 ppm) would improve the response characteristics, but there should be upper levels for each. Finally, the gas sensing mechanism of PANI/ZnPcCl{sub 16} films was also discussed. (semiconductor devices)

  5. Microwave assisted synthesis and characterisation of a zinc oxide/tobacco mosaic virus hybrid material. An active hybrid semiconductor in a field-effect transistor device

    Directory of Open Access Journals (Sweden)

    Shawn Sanctis

    2015-03-01

    Full Text Available Tobacco mosaic virus (TMV has been employed as a robust functional template for the fabrication of a TMV/zinc oxide field effect transistor (FET. A microwave based approach, under mild conditions was employed to synthesize stable zinc oxide (ZnO nanoparticles, employing a molecular precursor. Insightful studies of the decomposition of the precursor were done using NMR spectroscopy and material characterization of the hybrid material derived from the decomposition was achieved using dynamic light scattering (DLS, transmission electron microscopy (TEM, grazing incidence X-ray diffractometry (GI-XRD and atomic force microscopy (AFM. TEM and DLS data confirm the formation of crystalline ZnO nanoparticles tethered on top of the virus template. GI-XRD investigations exhibit an orientated nature of the deposited ZnO film along the c-axis. FET devices fabricated using the zinc oxide mineralized virus template material demonstrates an operational transistor performance which was achieved without any high-temperature post-processing steps. Moreover, a further improvement in FET performance was observed by adjusting an optimal layer thickness of the deposited ZnO on top of the TMV. Such a bio-inorganic nanocomposite semiconductor material accessible using a mild and straightforward microwave processing technique could open up new future avenues within the field of bio-electronics.

  6. Microwave assisted synthesis and characterisation of a zinc oxide/tobacco mosaic virus hybrid material. An active hybrid semiconductor in a field-effect transistor device.

    Science.gov (United States)

    Sanctis, Shawn; Hoffmann, Rudolf C; Eiben, Sabine; Schneider, Jörg J

    2015-01-01

    Tobacco mosaic virus (TMV) has been employed as a robust functional template for the fabrication of a TMV/zinc oxide field effect transistor (FET). A microwave based approach, under mild conditions was employed to synthesize stable zinc oxide (ZnO) nanoparticles, employing a molecular precursor. Insightful studies of the decomposition of the precursor were done using NMR spectroscopy and material characterization of the hybrid material derived from the decomposition was achieved using dynamic light scattering (DLS), transmission electron microscopy (TEM), grazing incidence X-ray diffractometry (GI-XRD) and atomic force microscopy (AFM). TEM and DLS data confirm the formation of crystalline ZnO nanoparticles tethered on top of the virus template. GI-XRD investigations exhibit an orientated nature of the deposited ZnO film along the c-axis. FET devices fabricated using the zinc oxide mineralized virus template material demonstrates an operational transistor performance which was achieved without any high-temperature post-processing steps. Moreover, a further improvement in FET performance was observed by adjusting an optimal layer thickness of the deposited ZnO on top of the TMV. Such a bio-inorganic nanocomposite semiconductor material accessible using a mild and straightforward microwave processing technique could open up new future avenues within the field of bio-electronics.

  7. Quantum Confinement of Hybrid Charge Transfer Excitons in GaN/InGaN/Organic Semiconductor Quantum Wells.

    Science.gov (United States)

    Panda, Anurag; Forrest, Stephen R

    2017-12-13

    We investigate hybrid charge transfer exciton (HCTE) confinement in organic-inorganic (OI) quantum wells (QWs) comprising a thin InGaN layer bound on one side by GaN and on the other by the organic semiconductors, tetraphenyldibenzoperiflanthene (DBP) or 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP). A binding energy of 10 meV is calculated for the Coulombically bound free HCTE state between a delocalized electron in GaN and a hole localized in DBP. The binding energy of the HCTE increases to 165 meV when the electron is confined to a 1.5 nm In0.21Ga0.79N QW (HCTEQW). The existence of the HCTEQW is confirmed by measuring the voltage-dependent DBP exciton dissociation yield at the OI heterojunction in the QW devices that decrease with increasing In concentration and decreasing electric field, matching the trends predicted by Poole-Frenkel emission. Combining spectroscopic measurements with optical models, we find that 14 ± 3% of the excitons that reach the GaN/DBP heterojunction form HCTEs and dissociate into free charges, while the remainder recombine. A high nonradiative recombination rate through defect states at the heterointerface account for the lack of observation of HCTEQW photoluminescence from GaN/InGaN/CBP QWs at temperatures as low as 10 K.

  8. Boosting fuel cell performance with a semiconductor photocatalyst: TiO2/Pt-Ru hybrid catalyst for methanol oxidation.

    Science.gov (United States)

    Drew, Kristine; Girishkumar, G; Vinodgopal, K; Kamat, Prashant V

    2005-06-23

    A hybrid carbon fiber electrode (CFE) consisting of TiO2 semiconductor photocatalyst and Pt-Ru catalyst has been developed to boost the performance of direct methanol fuel cells (DMFC). These two catalyst nanoparticles are deposited on opposite sides of the carbon fiber paper such that methanol oxidation is carried out catalytically on Pt-Ru and photocatalytically on TiO2 under UV-light irradiation. Since both catalysts carry out methanol oxidation independently, we observe an additive effect in the current generation. The carbon support fibers provide a large network to collect the electrons from both of these catalytic processes and thus assist in efficient current generation. In addition, TiO2 improves the performance of the Pt-Ru catalyst in dark, indicating possible surface area improvement or diminished poisoning effects. The concept of incorporating a photocatalyst provides new ways to minimize precious metal content and enhance the performance of DMFCs. At low catalyst loadings (0.15 mg/cm2) at 295 K, a 25% enhancement in the peak power density is observed upon illumination with light.

  9. Efficient Nitrogen Doping of Single-Layer Graphene Accompanied by Negligible Defect Generation for Integration into Hybrid Semiconductor Heterostructures.

    Science.gov (United States)

    Sarau, George; Heilmann, Martin; Bashouti, Muhammad; Latzel, Michael; Tessarek, Christian; Christiansen, Silke

    2017-03-22

    While doping enables application-specific tailoring of graphene properties, it can also produce high defect densities that degrade the beneficial features. In this work, we report efficient nitrogen doping of ∼11 atom % without virtually inducing new structural defects in the initial, large-area, low defect, and transferred single-layer graphene. To shed light on this remarkable high-doping-low-disorder relationship, a unique experimental strategy consisting of analyzing the changes in doping, strain, and defect density after each important step during the doping procedure was employed. Complementary micro-Raman mapping, X-ray photoelectron spectroscopy, and optical microscopy revealed that effective cleaning of the graphene surface assists efficient nitrogen incorporation accompanied by mild compressive strain resulting in negligible defect formation in the doped graphene lattice. These original results are achieved by separating the growth of graphene from its doping. Moreover, the high doping level occurred simultaneously with the epitaxial growth of n-GaN micro- and nanorods on top of graphene, leading to the flow of higher currents through the graphene/n-GaN rod interface. Our approach can be extended toward integrating graphene into other technologically relevant hybrid semiconductor heterostructures and obtaining an ohmic contact at their interfaces by adjusting the doping level in graphene.

  10. Surface plasmon enhanced energy transfer in metal-semiconductor hybrid nanostructures.

    Science.gov (United States)

    Zhao, Xinhong; Wang, Peng; Li, Baojun

    2011-08-01

    We report a type of hybrid nanostructures composed of ZnO nanoparticles, CdSe/ZnS core/shell quantum dots (QDs), and Ag nanoprisms. With ultraviolet light illumination, the energy absorbed by ZnO nanoparticles was transferred to the CdSe/ZnS core/shell QDs inducing a photoluminescence (PL) emission. To enhance the PL emission, Ag nanoprisms were doped in the ZnO nanoparticles and the QDs. Enhanced energy transfer from the ZnO nanoparticles to the QDs via the surface plasmon effect of the Ag nanoprisms was also demonstrated. The PL emission dependence was investigated as a function of the doped Ag nanoprism concentration and a 7.4 times PL enhancement was obtained at an Ag nanoprism concentration of 5 × 10(-8) M. This journal is © The Royal Society of Chemistry 2011

  11. Optimization of an extraordinary magnetoresistance sensor in the semiconductor-metal hybrid structure

    KAUST Repository

    Sun, Jian

    2010-11-01

    The purpose of this paper is to show by numerical computation how geometric parameters influence the Extraordinary Magnetoresistance (EMR) effect in an InAs-Au hybrid device. Symmetric IVVI and VIIV configurations were considered. The results show that the width and the length-width ratio of InAs are important geometrical parameters for the EMR effect along with the placement of the leads. Approximately the same EMR effect was obtained for both IVVI and VIIV configurations when the applied magnetic field ranged from -1T to 1T. In an optimized geometry the EMR effect can reach 43000% at 1Tesla for IVVI and 42700% at 1 Tesla for the VIIV configuration. ©2010 IEEE.

  12. Measurement of effective detective quantum efficiency for a photon counting scanning mammography system and comparison with two flat panel full-field digital mammography systems

    Science.gov (United States)

    Wood, Tim J.; Moore, Craig S.; Saunderson, John R.; Beavis, Andrew W.

    2018-01-01

    Effective detective quantum efficiency (eDQE) describes the resolution and noise properties of an imaging system along with scatter and primary transmission, all measured under clinically appropriate conditions. Effective dose efficiency (eDE) is the eDQE normalised to mean glandular dose and has been proposed as a useful metric for the optimisation of clinical imaging systems. The aim of this study was to develop a methodology for measuring eDQE and eDE on a Philips microdose mammography (MDM) L30 photon counting scanning system, and to compare performance with two conventional flat panel systems. A custom made lead-blocker was manufactured to enable the accurate determination of dose measurements, and modulation transfer functions were determined free-in-air at heights of 2, 4 and 6 cm above the breast support platform. eDQE were calculated for a Philips MDM L30, Hologic Dimensions and Siemens Inspiration digital mammography system for 2, 4 and 6 cm thick poly(methyl methacrylate) (PMMA). The beam qualities (target/filter and kilovoltage) assessed were those selected by the automatic exposure control, and anti-scatter grids were used where available. Measurements of eDQE demonstrate significant differences in performance between the slit- and scan-directions for the photon counting imaging system. MTF has been shown to be the limiting factor in the scan-direction, which results in a rapid fall in eDQE at mid-to-high spatial frequencies. A comparison with two flat panel mammography systems demonstrates that this may limit image quality for small details, such as micro-calcifications, which correlates with a more conventional image quality assessment with the CDMAM phantom. eDE has shown the scanning photon counting system offers superior performance for low spatial frequencies, which will be important for the detection of large low contrast masses. Both eDQE and eDE are proposed as useful metrics that should enable optimisation of the Philips MDM L30.

  13. Optimization of K-edge imaging for vulnerable plaques using gold nanoparticles and energy resolved photon counting detectors: a simulation study.

    Science.gov (United States)

    Alivov, Yahya; Baturin, Pavlo; Le, Huy Q; Ducote, Justin; Molloi, Sabee

    2014-01-06

    We investigated the effect of different imaging parameters, such as dose, beam energy, energy resolution and the number of energy bins, on the image quality of K-edge spectral computed tomography (CT) of gold nanoparticles (GNP) accumulated in an atherosclerotic plaque. A maximum likelihood technique was employed to estimate the concentration of GNP, which served as a targeted intravenous contrast material intended to detect the degree of the plaque's inflammation. The simulation studies used a single-slice parallel beam CT geometry with an x-ray beam energy ranging between 50 and 140 kVp. The synthetic phantoms included small (3 cm in diameter) cylinder and chest (33 × 24 cm(2)) phantoms, where both phantoms contained tissue, calcium and gold. In the simulation studies, GNP quantification and background (calcium and tissue) suppression tasks were pursued. The x-ray detection sensor was represented by an energy resolved photon counting detector (e.g., CdZnTe) with adjustable energy bins. Both ideal and more realistic (12% full width at half maximum (FWHM) energy resolution) implementations of the photon counting detector were simulated. The simulations were performed for the CdZnTe detector with a pixel pitch of 0.5-1 mm, which corresponds to a performance without significant charge sharing and cross-talk effects. The Rose model was employed to estimate the minimum detectable concentration of GNPs. A figure of merit (FOM) was used to optimize the x-ray beam energy (kVp) to achieve the highest signal-to-noise ratio with respect to the patient dose. As a result, the successful identification of gold and background suppression was demonstrated. The highest FOM was observed at the 125 kVp x-ray beam energy. The minimum detectable GNP concentration was determined to be approximately 1.06 µmol mL(-1) (0.21 mg mL(-1)) for an ideal detector and about 2.5 µmol mL(-1) (0.49 mg mL(-1)) for a more realistic (12% FWHM) detector. The studies show the optimal

  14. Optimization of the K-edge imaging for vulnerable plaques using gold nanoparticles and energy-resolved photon counting detectors: a simulation study

    Science.gov (United States)

    Alivov, Yahya; Baturin, Pavlo; Le, Huy Q.; Ducote, Justin; Molloi, Sabee

    2014-01-01

    We investigated the effect of different imaging parameters such as dose, beam energy, energy resolution, and number of energy bins on image quality of K-edge spectral computed tomography (CT) of gold nanoparticles (GNP) accumulated in an atherosclerotic plaque. Maximum likelihood technique was employed to estimate the concentration of GNP, which served as a targeted intravenous contrast material intended to detect the degree of plaque's inflammation. The simulations studies used a single slice parallel beam CT geometry with an X-ray beam energy ranging between 50 and 140 kVp. The synthetic phantoms included small (3 cm in diameter) cylinder and chest (33x24 cm2) phantom, where both phantoms contained tissue, calcium, and gold. In the simulation studies GNP quantification and background (calcium and tissue) suppression task were pursued. The X-ray detection sensor was represented by an energy resolved photon counting detector (e.g., CdZnTe) with adjustable energy bins. Both ideal and more realistic (12% FWHM energy resolution) implementations of photon counting detector were simulated. The simulations were performed for the CdZnTe detector with pixel pitch of 0.5-1 mm, which corresponds to the performance without significant charge sharing and cross-talk effects. The Rose model was employed to estimate the minimum detectable concentration of GNPs. A figure of merit (FOM) was used to optimize the X-ray beam energy (kVp) to achieve the highest signal-to-noise ratio (SNR) with respect to patient dose. As a result, the successful identification of gold and background suppression was demonstrated. The highest FOM was observed at 125 kVp X-ray beam energy. The minimum detectable GNP concentration was determined to be approximately 1.06 μmol/mL (0.21 mg/mL) for an ideal detector and about 2.5 μmol/mL (0.49 mg/mL) for more realistic (12% FWHM) detector. The studies show the optimal imaging parameters at lowest patient dose using an energy resolved photon counting detector

  15. Exploiting energy transfer in hybrid metal and semiconductor nanoparticle systems for biosensing and energy harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Mayilo, Sergiy

    2009-06-19

    In this work, gold and semiconductor nanoparticles are used as building blocks for nanostructures, in which energy transfer is investigated. Fluorescence quenching by gold nanoparticles is investigated and used to develop novel immunoassays for medically relevant molecules. The influence of gold nanoparticles on radiative and non-radiative rates of Cy3 and Cy3B dyes is studied here. A competitive, homogeneous immunoassay for digoxigenin and digoxin, a drug used to cure heart diseases, is developed. The assay has a limit of detection of 0.5 nM in buffer and 50 nM in serum. Time resolved spectroscopy reveals that the quenching is due to energy transfer with an efficiency of 70%. A homogeneous sandwich immunoassay for cardiac troponin T, an indicator of damage to the heart muscle, is developed. Gold nanoparticles and fluorophores are functionalized with anti-troponin T antibodies. In the presence of troponin T the nanoparticles and fluorophores form a sandwich structure, in which the dye fluorescence is quenched by a gold nanoparticle. The limit of detection of the immunoassay in buffer is 0.02 nM and 0.11 nM in serum. Energy transfer is demonstrated in clusters of CdTe nanocrystals assembled using three methods. In the first method, clusters of differently-sized water soluble CdTe nanocrystals capped by negatively charged mercaptoacid stabilizers are produced through electrostatic interactions with positively charged Ca{sup 2+} cations. The two other methods employ covalent binding through dithiols and thiolated DNA as linkers between nanocrystals. Energy transfer from smaller nanocrystals to larger nanocrystals in aggregates is demonstrated by means of steady-state and time-resolved photoluminescence spectroscopy, paving the way for nanocrystal-based light harvesting structures in solution. Multi-shell onion-like CdSe/ZnS/CdSe/ZnS nanocrystals are presented. The shade of the white light can be controlled by annealing the particles. Evidence for intra

  16. Organic-inorganic semiconductor hybrid systems. Structure, morphology, and electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    El Helou, Mira

    2012-08-22

    This dissertation addresses the preparation and characterization of hybrid semiconducting systems combining organic with inorganic materials. Characterization methods used included to determine the structure, morphology, and thermal stability comprised X-ray diffraction (XRD), atomic force microscopy (AFM), thermal desorption spectroscopy (TDS), and X-ray photoelectron spectroscopy (XPS). One organic-inorganic semiconducting system was pentacene (C{sub 22}H{sub 14}) and zinc oxide. This interface was investigated in detail for pentacene on an oxygen-terminated zinc oxide surface, i.e. ZnO(000 anti 1). An extended study on the promising p-n junction was carried out for pentacene on ZnO with different orientations which exhibit different chemical and structural characteristics: ZnO(000 anti 1), ZnO(0001), and ZnO(10 anti 10). Moreover, the organic crystal structure of pentacene was selectively tuned by carefully choosing the substrate temperature. This defined interface with a physisorbed pentacene layer on ZnO was characterized by optical absorption which depends on the temperature of the measured system, the pentacene film thickness, and the molecular orientation and packing. The high quality of the pentacene films allowed in one case to characterize the Davydov splitting by linear polarized light focused on a single crystallite. Another subject in the field of organic-inorganic hybrid materials comprised conjugated dithiols used as self-assembled monolayers (SAMs) for immobilizing semiconducting CdS nanoparticles (NPs) on Au substrates. It was demonstrated that an appropriate selection and preparation of the conjugated SAMs is crucial for building up a light-addressable potentiometric sensor with a sufficient efficiency. An optimized electron transfer was achieved with SAMs of long range ordering, high stability, and adequate conductivity. This was examined for different linkers and was best for stilbenedithiol immobilized in solution at higher temperatures. Due

  17. Magnetic-field-driven electron transport in ferromagnetic/ insulator/semiconductor hybrid structures

    Science.gov (United States)

    Volkov, N. V.; Tarasov, A. S.; Rautskii, M. V.; Lukyanenko, A. V.; Varnakov, S. N.; Ovchinnikov, S. G.

    2017-10-01

    Extremely large magnetotransport phenomena were found in the simple devices fabricated on base of the Me/SiO2/p-Si hybrid structures (where Me are Mn and Fe). These effects include gigantic magnetoimpedance (MI), dc magnetoresistance (MR) and the lateral magneto-photo-voltaic effect (LMPE). The MI and MR values exceed 106% in magnetic field about 0.2 T for Mn/SiO2/p-Si Schottky diode. LMPE observed in Fe/SiO2/p-Si lateral device reaches the value of 104% in a field of 1 T. We believe that in case with the Schottky diode MR and MI effects are originate from magnetic field influence on impact ionization process by two different ways. First, the trajectory of the electron is deflected by a magnetic field, which suppresses acquisition of kinetic energy and therefore impact ionization. Second, the magnetic field gives rise to shift of the acceptor energy levels in silicon to a higher energy. As a result, the activation energy for impact ionization significantly increases and consequently threshold voltage rises. Moreover, the second mechanism (acceptor level energy shifting in magnetic field) can be responsible for giant LMPE.

  18. Algorithm for Detection of Ground and Canopy Cover in Micropulse Photon-Counting Lidar Altimeter Data in Preparation for the ICESat-2 Mission

    Science.gov (United States)

    Herzfeld, Ute Christina; McDonald, Brian W.; Neumann, Thomas Allen; Wallin, Bruce F.; Neumann, Thomas A.; Markus, Thorsten; Brenner, Anita; Field, Christopher

    2014-01-01

    NASA's Ice, Cloud and Land Elevation Satellite-II (ICESat-2) mission is a decadal survey mission (2016 launch). The mission objectives are to measure land ice elevation, sea ice freeboard, and changes in these variables, as well as to collect measurements over vegetation to facilitate canopy height determination. Two innovative components will characterize the ICESat-2 lidar: 1) collection of elevation data by a multibeam system and 2) application of micropulse lidar (photon-counting) technology. A photon-counting altimeter yields clouds of discrete points, resulting from returns of individual photons, and hence new data analysis techniques are required for elevation determination and association of the returned points to reflectors of interest. The objective of this paper is to derive an algorithm that allows detection of ground under dense canopy and identification of ground and canopy levels in simulated ICESat-2 data, based on airborne observations with a Sigma Space micropulse lidar. The mathematical algorithm uses spatial statistical and discrete mathematical concepts, including radial basis functions, density measures, geometrical anisotropy, eigenvectors, and geostatistical classification parameters and hyperparameters. Validation shows that ground and canopy elevation, and hence canopy height, can be expected to be observable with high accuracy by ICESat-2 for all expected beam energies considered for instrument design (93.01%-99.57% correctly selected points for a beam with expected return of 0.93 mean signals per shot (msp), and 72.85%-98.68% for 0.48 msp). The algorithm derived here is generally applicable for elevation determination from photoncounting lidar altimeter data collected over forested areas, land ice, sea ice, and land surfaces, as well as for cloud detection.

  19. Front-end electronics for multichannel semiconductor detector systems

    CERN Document Server

    Grybos, P

    2010-01-01

    Front-end electronics for multichannel semiconductor detektor systems Volume 08, EuCARD Editorial Series on Accelerator Science and Technology The monograph is devoted to many different aspects related to front-end electronics for semiconductor detector systems, namely: − designing and testing silicon position sensitive detectors for HEP experiments and X-ray imaging applications, − designing and testing of multichannel readout electronics for semiconductor detectors used in X-ray imaging applications, especially for noise minimization, fast signal processing, crosstalk reduction and good matching performance, − optimization of semiconductor detection systems in respect to the effects of radiation damage. The monograph is the result mainly of the author's experience in the above-mentioned areas and it is an attempt of a comprehensive presentation of issues related to the position sensitive detection system working in a single photon counting mode and intended to X-ray imaging applications. The structure...

  20. PIXIE III: a very large area photon-counting CMOS pixel ASIC for sharp X-ray spectral imaging

    Science.gov (United States)

    Bellazzini, R.; Brez, A.; Spandre, G.; Minuti, M.; Pinchera, M.; Delogu, P.; de Ruvo, P. L.; Vincenzi, A.

    2015-01-01

    PIXIE III is the third generation of very large area (32 × 25 mm2) pixel ASICs developed by Pixirad Imaging Counters s.r.l. to be used in combination with suitable X-ray sensor materials (Silicon, CdTe, GaAs) in hybrid assemblies using flip-chip bonding. A Pixirad unit module based on PIXIE III shows several advances compared to what has been available up to now. It has a very broad energy range (from 2 to 100 keV before full pulse saturation), high speed (100 ns peaking time), high frame rate (larger than 500 fps), dead-time-free operation, good energy resolution (around 2 keV at 20 keV), high photo-peak fraction and sharp spectral separation between the color images. In this paper the results obtained with PIXIE III both in a test bench set-up as well in X-ray imaging applications are discussed.

  1. Development of superconducting tunnel junction as photon counting detector in astronomy; Developpement de jonctions supraconductrices a effet tunnel pour le comptage de photons en astronomie

    Energy Technology Data Exchange (ETDEWEB)

    Jorel, C

    2004-12-15

    This work describes the development of S/Al-AlOx-Al/S Superconducting Tunnel Junctions (STJ) to count photons for astronomical applications in the near-infrared. The incoming light energy is converted into excited charges in a superconducting layer (S, either Nb or Ta) with a population proportional to the deposited energy. The photon energy can thus be evaluated by integrating the tunnel current induced in a voltage biased junction at a very low temperature (100 mK). The performance of STJ for light detection is discussed in the first chapter and compared with the best performances obtained with other techniques based on either superconductors. At the beginning of the thesis, a previous manufacturing process made it possible to obtain good quality Nb based junctions and preliminary results for photon counting. The objective of the thesis was to replace Nb as absorber with Ta, an intrinsically more sensitive material, and secondly to develop a new and more efficient manufacturing process. We first focused on the optimization of the Tantalum thin film quality. Structural analysis showed that these films can be grown epitaxially by magnetron sputtering onto an R-plane sapphire substrate heated to 600 Celsius degrees and covered by a thin Nb buffer layer. Electrical transport measurement from room to low temperatures gave excellent Relative Resistive Ratios of about 50 corresponding to mean free path of the order of 100 nm. Then, we conceived an original manufacturing process batch on 3 inch diameter sapphire substrate with five mask levels. These masks made it possible to produce single pixel STJ of different sizes (from 25*25 to 50*50 square microns) and shapes. We also produced multiple junctions onto a common absorber as well as 9-pixel arrays. Thanks to the development of this process we obtained a very large percentage of quality junctions (>90%) with excellent measured normal resistances of a few micro-ohm cm{sup 2} and low leakage currents of the order of one

  2. SU-C-206-01: Impact of Charge Sharing Effect On Sub-Pitch Resolution for CZT-Based Photon Counting CT Systems

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, X; Cheng, Z; Deen, J; Peng, H [McMaster University, Hamilton, Ontario (Canada); Xing, L [Stanford University School of Medicine, Stanford, CA (United States)

    2016-06-15

    Purposes: Photon counting CT is a new imaging technology that can provide tissue composition information such as calcium/iodine content quantification. Cadmium zinc telluride CZT is considered a good candidate the photon counting CT due to its relatively high atomic number and band gap. One potential challenge is the degradation of both spatial and energy resolution as the fine electrode pitch is deployed (<50 µm). We investigated the extent of charge sharing effect as functions of gap width, bias voltage and depth-of-interaction (DOI). Methods: The initial electron cloud size and diffusion process were modeled analytically. The valid range of charge sharing effect refers to the range over which both signals of adjacent electrodes are above the triggering threshold (10% of the amplitude of 60keV X-ray photons). The intensity ratios of output in three regions (I1/I2/I3: left pixel, gap area and right pixel) were calculated. With Gaussian white noises modeled (a SNR of 5 based upon the preliminary experiments), the sub-pitch resolution as a function of the spatial position in-between two pixels was studied. Results: The valid range of charge sharing increases linearly with depth-of-interaction (DOI) but decreases with gap width and bias voltage. For a 1.5mm thickness CZT detector (pitch: 50µm, bias: 400 V), the range increase from ∼90µm up to ∼110µm. Such an increase can be attributed to a longer travel distance and the associated electron cloud broadening. The achievable sub-pitch resolution is in the range of ∼10–30µm. Conclusion: The preliminary results demonstrate that sub-pixel spatial resolution can be achieved using the ratio of amplitudes of two neighboring pixels. Such ratio may also be used to correct charge loss and help improve energy resolution of a CZT detector. The impact of characteristic X-rays hitting adjacent pixels (i.e., multiple interaction) on charge sharing is currently being investigated.

  3. ChromAIX2: A large area, high count-rate energy-resolving photon counting ASIC for a Spectral CT Prototype

    Science.gov (United States)

    Steadman, Roger; Herrmann, Christoph; Livne, Amir

    2017-08-01

    Spectral CT based on energy-resolving photon counting detectors is expected to deliver additional diagnostic value at a lower dose than current state-of-the-art CT [1]. The capability of simultaneously providing a number of spectrally distinct measurements not only allows distinguishing between photo-electric and Compton interactions but also discriminating contrast agents that exhibit a K-edge discontinuity in the absorption spectrum, referred to as K-edge Imaging [2]. Such detectors are based on direct converting sensors (e.g. CdTe or CdZnTe) and high-rate photon counting electronics. To support the development of Spectral CT and show the feasibility of obtaining rates exceeding 10 Mcps/pixel (Poissonian observed count-rate), the ChromAIX ASIC has been previously reported showing 13.5 Mcps/pixel (150 Mcps/mm2 incident) [3]. The ChromAIX has been improved to offer the possibility of a large area coverage detector, and increased overall performance. The new ASIC is called ChromAIX2, and delivers count-rates exceeding 15 Mcps/pixel with an rms-noise performance of approximately 260 e-. It has an isotropic pixel pitch of 500 μm in an array of 22×32 pixels and is tile-able on three of its sides. The pixel topology consists of a two stage amplifier (CSA and Shaper) and a number of test features allowing to thoroughly characterize the ASIC without a sensor. A total of 5 independent thresholds are also available within each pixel, allowing to acquire 5 spectrally distinct measurements simultaneously. The ASIC also incorporates a baseline restorer to eliminate excess currents induced by the sensor (e.g. dark current and low frequency drifts) which would otherwise cause an energy estimation error. In this paper we report on the inherent electrical performance of the ChromAXI2 as well as measurements obtained with CZT (CdZnTe)/CdTe sensors and X-rays and radioactive sources.

  4. An Algorithm for Detection of Ground and Canopy Cover in Micropulse Photon-Counting Lidar Altimeter Data in Preparation of the ICESat-2 Mission

    Science.gov (United States)

    Herzfeld, Ute C.; McDonald, Brian W.; Wallins, Bruce F.; Markus, Thorsten; Neumann, Thomas A.; Brenner, Anita

    2012-01-01

    The Ice, Cloud and Land Elevation Satellite-II (ICESat-2) mission has been selected by NASA as a Decadal Survey mission, to be launched in 2016. Mission objectives are to measure land ice elevation, sea ice freeboard/ thickness and changes in these variables and to collect measurements over vegetation that will facilitate determination of canopy height, with an accuracy that will allow prediction of future environmental changes and estimation of sea-level rise. The importance of the ICESat-2 project in estimation of biomass and carbon levels has increased substantially, following the recent cancellation of all other planned NASA missions with vegetation-surveying lidars. Two innovative components will characterize the ICESat-2 lidar: (1) Collection of elevation data by a multi-beam system and (2) application of micropulse lidar (photon counting) technology. A micropulse photon-counting altimeter yields clouds of discrete points, which result from returns of individual photons, and hence new data analysis techniques are required for elevation determination and association of returned points to reflectors of interest including canopy and ground in forested areas. The objective of this paper is to derive and validate an algorithm that allows detection of ground under dense canopy and identification of ground and canopy levels in simulated ICESat-2-type data. Data are based on airborne observations with a Sigma Space micropulse lidar and vary with respect to signal strength, noise levels, photon sampling options and other properties. A mathematical algorithm is developed, using spatial statistical and discrete mathematical concepts, including radial basis functions, density measures, geometrical anisotropy, eigenvectors and geostatistical classification parameters and hyperparameters. Validation shows that the algorithm works very well and that ground and canopy elevation, and hence canopy height, can be expected to be observable with a high accuracy during the ICESat

  5. Size-dependent scanning parameters (kVp and mAs) for photon-counting spectral CT system in pediatric imaging: simulation study.

    Science.gov (United States)

    Chen, Han; Danielsson, Mats; Xu, Cheng

    2016-06-07

    We are developing a photon-counting spectral CT detector with a small pixel size of [Formula: see text] mm(2), offering a potential advantage for better visualization of small structures in pediatric patients. The purpose of this study is to determine the patient size dependent scanning parameters (kVp and mAs) for pediatric CT in two imaging cases: adipose imaging and iodinated blood imaging. Cylindrical soft-tissue phantoms of diameters between 10-25 cm were used to mimic patients of different ages from 0 to 15 y. For adipose imaging, a 5 mm diameter adipose sphere was assumed as an imaging target, while in the case of iodinated imaging, an iodinated blood sphere of 1 mm in diameter was assumed. By applying the geometry of a commercial CT scanner (GE Lightspeed VCT), simulations were carried out to calculate the detectability index, [Formula: see text], with tube potentials varying from 40 to 140 kVp. The optimal kVp for each phantom in each imaging case was determined such that the dose-normalized detectability index, [Formula: see text]dose, is maximized. With the assumption that the detectability index in pediatric imaging is required the same as in typical adult imaging, the value of mAs at optimal kVp for each phantom was selected to achieve a reference detectability index that was obtained by scanning an adult phantom (30 cm in diameter) in a typical adult CT procedure (120 kVp and 200 mAs) using a modeled energy-integrating system. For adipose imaging, the optimal kVps are 50, 60, 80, and 120 kVp, respectively, for phantoms of 10, 15, 20, and 25 cm in diameter. The corresponding mAs values required to achieve the reference detectability index are only 9%, 23%, 24%, and 54% of the mAs that is used for adult patients at 120 kVp, for 10, 15, 20, and 25 cm diameter phantoms, respectively. In the case of iodinated imaging, a tube potential of 60 kVp was found optimal for all phantoms investigated, and the mAs values required to achieve the reference

  6. 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).

  7. Direct measurement of the long-range p -d exchange coupling in a ferromagnet-semiconductor Co/CdMgTe/CdTe quantum well hybrid structure

    Science.gov (United States)

    Akimov, I. A.; Salewski, M.; Kalitukha, I. V.; Poltavtsev, S. V.; Debus, J.; Kudlacik, D.; Sapega, V. F.; Kopteva, N. E.; Kirstein, E.; Zhukov, E. A.; Yakovlev, D. R.; Karczewski, G.; Wiater, M.; Wojtowicz, T.; Korenev, V. L.; Kusrayev, Yu. G.; Bayer, M.

    2017-11-01

    The exchange interaction between magnetic ions and charge carriers in semiconductors is considered to be a prime tool for spin control. Here, we solve a long-standing problem by uniquely determining the magnitude of the long-range p -d exchange interaction in a ferromagnet-semiconductor (FM-SC) hybrid structure where a 10-nm-thick CdTe quantum well is separated from the FM Co layer by a CdMgTe barrier with a thickness on the order of 10 nm. The exchange interaction is manifested by the spin splitting of acceptor bound holes in the effective magnetic field induced by the FM. The exchange splitting is directly evaluated using spin-flip Raman scattering by analyzing the dependence of the Stokes shift ΔS on the external magnetic field B . We show that in a strong magnetic field, ΔS is a linear function of B with an offset of Δp d=50 -100 μ eV at zero field from the FM induced effective exchange field. On the other hand, the s -d exchange interaction between conduction band electrons and FM, as well as the p -d contribution for free valence band holes, are negligible. The results are well described by the model of indirect exchange interaction between acceptor bound holes in the CdTe quantum well and the FM layer mediated by elliptically polarized phonons in the hybrid structure.

  8. Characterization of a mammographic system based on single photon counting pixel arrays coupled to GaAs x-ray detectors.

    Science.gov (United States)

    Amendolia, S R; Bisogni, M G; Delogu, P; Fantacci, M E; Paternoster, G; Rosso, V; Stefanini, A

    2009-04-01

    The authors report on the imaging capabilities of a mammographic system demonstrator based on GaAs pixel detectors operating in single photon counting (SPC) mode. The system imaging performances have been assessed by means of the transfer functions: The modulation transfer function (MTF), the normalized noise power spectrum, and the detective quantum efficiency (DQE) have been measured following the guidelines of the IEC 62220-1-2 protocol. The transfer function analysis has shown the high spatial resolution capabilities of the GaAs detectors. The MTF calculated at the Nyquist frequency (2.94 cycles/mm) is indeed 60%. The DQE, measured with a standard mammographic beam setup (Mo/Mo, 28 kVp, with 4 mm Al added filter) and calculated at zero frequency, is 46%. Aiming to further improve the system's image quality, the authors investigate the DQE limiting factors and show that they are mainly related to system engineering. For example, the authors show that optimization of the image equalization procedure increases the DQE(0) up to 74%, which is better than the DQE(0) of most clinical mammographic systems. The authors show how the high detection efficiency of GaAs detectors and the noise discrimination associated with the SPC technology allow optimizing the image quality in mammography. In conclusion, the authors propose technological solutions to exploit to the utmost the potentiality of GaAs detectors coupled to SPC electronics.

  9. A Ring Artifact Correction Method: Validation by Micro-CT Imaging with Flat-Panel Detectors and a 2D Photon-Counting Detector

    Directory of Open Access Journals (Sweden)

    Mohamed Elsayed Eldib

    2017-01-01

    Full Text Available We introduce an efficient ring artifact correction method for a cone-beam computed tomography (CT. In the first step, we correct the defective pixels whose values are close to zero or saturated in the projection domain. In the second step, we compute the mean value at each detector element along the view angle in the sinogram to obtain the one-dimensional (1D mean vector, and we then compute the 1D correction vector by taking inverse of the mean vector. We multiply the correction vector with the sinogram row by row over all view angles. In the third step, we apply a Gaussian filter on the difference image between the original CT image and the corrected CT image obtained in the previous step. The filtered difference image is added to the corrected CT image to compensate the possible contrast anomaly that may appear due to the contrast change in the sinogram after removing stripe artifacts. We applied the proposed method to the projection data acquired by two flat-panel detectors (FPDs and a silicon-based photon-counting X-ray detector (PCXD. Micro-CT imaging experiments of phantoms and a small animal have shown that the proposed method can greatly reduce ring artifacts regardless of detector types. Despite the great reduction of ring artifacts, the proposed method does not compromise the original spatial resolution and contrast.

  10. Characterization of a mammographic system based on single photon counting pixel arrays coupled to GaAs x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Amendolia, S. R.; Bisogni, M. G.; Delogu, P.; Fantacci, M. E.; Paternoster, G.; Rosso, V.; Stefanini, A. [Str. Dip. di Matematica e Fisica dell' Universita di Sassari, Via Vienna 2, I-07100, Sassari (Italy) and Istituto Nazionale di Fisica Nucleare INFN Sezione di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy); Dip. di Fisica ' ' E. Fermi' ' , Universita di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy) and Istituto Nazionale di Fisica Nucleare INFN Sezione di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy); Dip. di Fisica ' ' E. Fermi' ' , Universita di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy); Dip. di Fisica ' ' E. Fermi' ' , Universita di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy) and Istituto Nazionale di Fisica Nucleare INFN Sezione di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy)

    2009-04-15

    The authors report on the imaging capabilities of a mammographic system demonstrator based on GaAs pixel detectors operating in single photon counting (SPC) mode. The system imaging performances have been assessed by means of the transfer functions: The modulation transfer function (MTF), the normalized noise power spectrum, and the detective quantum efficiency (DQE) have been measured following the guidelines of the IEC 62220-1-2 protocol. The transfer function analysis has shown the high spatial resolution capabilities of the GaAs detectors. The MTF calculated at the Nyquist frequency (2.94 cycles/mm) is indeed 60%. The DQE, measured with a standard mammographic beam setup (Mo/Mo, 28 kVp, with 4 mm Al added filter) and calculated at zero frequency, is 46%. Aiming to further improve the system's image quality, the authors investigate the DQE limiting factors and show that they are mainly related to system engineering. For example, the authors show that optimization of the image equalization procedure increases the DQE(0) up to 74%, which is better than the DQE(0) of most clinical mammographic systems. The authors show how the high detection efficiency of GaAs detectors and the noise discrimination associated with the SPC technology allow optimizing the image quality in mammography. In conclusion, the authors propose technological solutions to exploit to the utmost the potentiality of GaAs detectors coupled to SPC electronics.

  11. Material decomposition through weighted imaged subtraction in dual-energy spectral mammography with an energy-resolved photon-counting detector using Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Eom, Ji Soo; Kang, Soon Cheol; Lee, Seung Wan [Konyang University, Daejeon (Korea, Republic of)

    2017-09-15

    Mammography is commonly used for screening early breast cancer. However, mammographic images, which depend on the physical properties of breast components, are limited to provide information about whether a lesion is malignant or benign. Although a dual-energy subtraction technique decomposes a certain material from a mixture, it increases radiation dose and degrades the accuracy of material decomposition. In this study, we simulated a breast phantom using attenuation characteristics, and we proposed a technique to enable the accurate material decomposition by applying weighting factors for the dual-energy mammography based on a photon-counting detector using a Monte Carlo simulation tool. We also evaluated the contrast and noise of simulated breast images for validating the proposed technique. As a result, the contrast for a malignant tumor in the dual-energy weighted subtraction technique was 0.98 and 1.06 times similar than those in the general mammography and dual-energy subtraction techniques, respectively. However the contrast between malignant and benign tumors dramatically increased 13.54 times due to the low contrast of a benign tumor. Therefore, the proposed technique can increase the material decomposition accuracy for malignant tumor and improve the diagnostic accuracy of mammography.

  12. Dose optimization for dual-energy contrast-enhanced digital mammography based on an energy-resolved photon-counting detector: A Monte Carlo simulation study

    Science.gov (United States)

    Lee, Youngjin; Lee, Seungwan; Kang, Sooncheol; Eom, Jisoo

    2017-03-01

    Dual-energy contrast-enhanced digital mammography (CEDM) has been used to decompose breast images and improve diagnostic accuracy for tumor detection. However, this technique causes an increase of radiation dose and an inaccuracy in material decomposition due to the limitations of conventional X-ray detectors. In this study, we simulated the dual-energy CEDM with an energy-resolved photon-counting detector (ERPCD) for reducing radiation dose and improving the quantitative accuracy of material decomposition images. The ERPCD-based dual-energy CEDM was compared to the conventional dual-energy CEDM in terms of radiation dose and quantitative accuracy. The correlation between radiation dose and image quality was also evaluated for optimizing the ERPCD-based dual-energy CEDM technique. The results showed that the material decomposition errors of the ERPCD-based dual-energy CEDM were 0.56-0.67 times lower than those of the conventional dual-energy CEDM. The imaging performance of the proposed technique was optimized at the radiation dose of 1.09 mGy, which is a half of the MGD for a single view mammogram. It can be concluded that the ERPCD-based dual-energy CEDM with an optimal exposure level is able to improve the quality of material decomposition images as well as reduce radiation dose.

  13. Comparison of image uniformity with photon counting and conventional scintillation single-photon emission computed tomography system: A Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ho Chul; Lee, Young Jin [Dept. of Radiological Science, Eulji University, Seongnam (Korea, Republic of); Kim, Hee Joung; Kim, Kyuseok; Lee, Min Hee [Yonsei University, Wonju (Korea, Republic of)

    2017-06-15

    To avoid imaging artifacts and interpretation mistakes, an improvement of the uniformity in gamma camera systems is a very important point. We can expect excellent uniformity using cadmium zinc telluride (CZT) photon counting detector (PCD) because of the direct conversion of the gamma rays energy into electrons. In addition, the uniformity performance such as integral uniformity (IU), differential uniformity (DU), scatter fraction (SF), and contrast-to-noise ratio (CNR) varies according to the energy window setting. In this study, we compared a PCD and conventional scintillation detector with respect to the energy windows (5%, 10%, 15%, and 20%) using a {sup 99m}Tc gamma source with a Geant4 Application for Tomography Emission simulation tool. The gamma camera systems used in this work are a CZT PCD and NaI(Tl) conventional scintillation detector with a 1-mm thickness. According to the results, although the IU and DU results were improved with the energy window, the SF and CNR results deteriorated with the energy window. In particular, the uniformity for the PCD was higher than that of the conventional scintillation detector in all cases. In conclusion, our results demonstrated that the uniformity of the CZT PCD was higher than that of the conventional scintillation detector.

  14. Characterization of the Photon Counting CHASE Jr., Chip Built in a 40-nm CMOS Process With a Charge Sharing Correction Algorithm Using a Collimated X-Ray Beam

    Energy Technology Data Exchange (ETDEWEB)

    Krzyżanowska, A. [AGH-UST, Cracow; Deptuch, G. W. [Fermilab; Maj, P. [AGH-UST, Cracow; Gryboś, P. [AGH-UST, Cracow; Szczygieł, R. [AGH-UST, Cracow

    2017-08-01

    This paper presents the detailed characterization of a single photon counting chip, named CHASE Jr., built in a CMOS 40-nm process, operating with synchrotron radiation. The chip utilizes an on-chip implementation of the C8P1 algorithm. The algorithm eliminates the charge sharing related uncertainties, namely, the dependence of the number of registered photons on the discriminator’s threshold, set for monochromatic irradiation, and errors in the assignment of an event to a certain pixel. The article presents a short description of the algorithm as well as the architecture of the CHASE Jr., chip. The analog and digital functionalities, allowing for proper operation of the C8P1 algorithm are described, namely, an offset correction for two discriminators independently, two-stage gain correction, and different operation modes of the digital blocks. The results of tests of the C8P1 operation are presented for the chip bump bonded to a silicon sensor and exposed to the 3.5- μm -wide pencil beam of 8-keV photons of synchrotron radiation. It was studied how sensitive the algorithm performance is to the chip settings, as well as the uniformity of parameters of the analog front-end blocks. Presented results prove that the C8P1 algorithm enables counting all photons hitting the detector in between readout channels and retrieving the actual photon energy.

  15. Comparison of Image Uniformity with Photon Counting and Conventional Scintillation Single-Photon Emission Computed Tomography System: A Monte Carlo Simulation Study

    Directory of Open Access Journals (Sweden)

    Ho Chul Kim

    2017-06-01

    Full Text Available To avoid imaging artifacts and interpretation mistakes, an improvement of the uniformity in gamma camera systems is a very important point. We can expect excellent uniformity using cadmium zinc telluride (CZT photon counting detector (PCD because of the direct conversion of the gamma rays energy into electrons. In addition, the uniformity performance such as integral uniformity (IU, differential uniformity (DU, scatter fraction (SF, and contrast-to-noise ratio (CNR varies according to the energy window setting. In this study, we compared a PCD and conventional scintillation detector with respect to the energy windows (5%, 10%, 15%, and 20% using a 99mTc gamma source with a Geant4 Application for Tomography Emission simulation tool. The gamma camera systems used in this work are a CZT PCD and NaI(Tl conventional scintillation detector with a 1-mm thickness. According to the results, although the IU and DU results were improved with the energy window, the SF and CNR results deteriorated with the energy window. In particular, the uniformity for the PCD was higher than that of the conventional scintillation detector in all cases. In conclusion, our results demonstrated that the uniformity of the CZT PCD was higher than that of the conventional scintillation detector.

  16. Precision lifetime measurements of Cs 6p 2P1/2 and 6p 2P3/2 levels by single-photon counting

    Science.gov (United States)

    Young, L.; Hill, W. T., III; Sibener, S. J.; Price, Stephen D.; Tanner, C. E.; Wieman, C. E.; Leone, Stephen R.

    1994-09-01

    Time-correlated single-photon counting is used to measure the lifetimes of the 6p 2P1/2 and 6p 2P3/2 levels in atomic Cs with accuracies ~=0.2-0.3 %. A high-repetition-rate, femtosecond, self-mode-locked Ti:sapphire laser is used to excite Cs produced in a well-collimated atomic beam. The time interval between the excitation pulse and the arrival of a fluorescence photon is measured repetitively until the desired statistics are obtained. The lifetime results are 34.75(7) and 30.41(10) ns for the 6p 2P1/2 and 6p 2P3/2 levels, respectively. These lifetimes fall between those extracted from ab initio many-body perturbation-theory calculations by Blundell, Johnson, and Sapirstein [Phys. Rev. A 43, 3407 (1991)] and V. A. Dzuba et al. [Phys. Lett. A 142, 373 (1989)] and are in all cases within 0.9% of the calculated values. The measurement errors are dominated by systematic effects, and methods to alleviate these and to approach an accuracy of 0.1% are discussed. The technique is a viable alternative to the fast-beam laser approach for measuring lifetimes with extreme accuracy.

  17. Limits on Achievable Dimensional and Photon Efficiencies with Intensity-Modulation and Photon-Counting Due to Non-Ideal Photon-Counter Behavior

    Science.gov (United States)

    Moision, Bruce; Erkmen, Baris I.; Farr, William; Dolinar, Samuel J.; Birnbaum, Kevin M.

    2012-01-01

    An ideal intensity-modulated photon-counting channel can achieve unbounded photon information efficiencies (PIEs). However, a number of limitations of a physical system limit the practically achievable PIE. In this paper, we discuss several of these limitations and illustrate their impact on the channel. We show that, for the Poisson channel, noise does not strictly bound PIE, although there is an effective limit, as the dimensional information efficiency goes as e[overline] e PIE beyond a threshold PIE. Since the Holevo limit is bounded in the presence of noise, this illustrates that the Poisson approximation is invalid at large PIE for any number of noise modes. We show that a finite transmitter extinction ratio bounds the achievable PIE to a maximum that is logarithmic in the extinction ratio. We show how detector jitter limits the ability to mitigate noise in the PPM signaling framework. We illustrate a method to model detector blocking when the number of detectors is large, and illustrate mitigation of blocking with spatial spreading and altering. Finally, we illustrate the design of a high photon efficiency system using state-of-the-art photo-detectors and taking all these effects into account.

  18. Estimation of Basis Line-Integrals in a Spectral Distortion-Modeled Photon Counting Detector Using Low-Order Polynomial Approximation of X-ray Transmittance.

    Science.gov (United States)

    Okkyun Lee; Kappler, Steffen; Polster, Christoph; Taguchi, Katsuyuki

    2017-02-01

    Photon counting detector (PCD)-based computed tomography exploits spectral information from a transmitted x-ray spectrum to estimate basis line-integrals. The recorded spectrum, however, is distorted and deviates from the transmitted spectrum due to spectral response effect (SRE). Therefore, the SRE needs to be compensated for when estimating basis line-integrals. One approach is to incorporate the SRE model with an incident spectrum into the PCD measurement model and the other approach is to perform a calibration process that inherently includes both the SRE and the incident spectrum. A maximum likelihood estimator can be used to the former approach, which guarantees asymptotic optimality; however, a heavy computational burden is a concern. Calibration-based estimators are a form of the latter approach. They can be very efficient; however, a heuristic calibration process needs to be addressed. In this paper, we propose a computationally efficient three-step estimator for the former approach using a low-order polynomial approximation of x-ray transmittance. The low-order polynomial approximation can change the original non-linear estimation method to a two-step linearized approach followed by an iterative bias correction step. We show that the calibration process is required only for the bias correction step and prove that it converges to the unbiased solution under practical assumptions. Extensive simulation studies validate the proposed method and show that the estimation results are comparable to those of the ML estimator while the computational time is reduced substantially.

  19. Preliminary test of an imaging probe for nuclear medicine using hybrid pixel detectors

    CERN Document Server

    Bertolucci, Ennio; Mettivier, G; Montesi, M C; Russo, P

    2002-01-01

    We are investigating the feasibility of an intraoperative imaging probe for lymphoscintigraphy with Tc-99m tracer, for sentinel node radioguided surgery, using the Medipix series of hybrid detectors coupled to a collimator. These detectors are pixelated semiconductor detectors bump-bonded to the Medipix1 photon counting read-out chip (64x64 pixel, 170 mu m pitch) or to the Medipix2 chip (256x256 pixel, 55 mu m pitch), developed by the European Medipix collaboration. The pixel detector we plan to use in the final version of the probe is a semi-insulating GaAs detector or a 1-2 mm thick CdZnTe detector. For the preliminary tests presented here, we used 300-mu m thick silicon detectors, hybridized via bump-bonding to the Medipix1 chip. We used a tungsten parallel-hole collimator (7 mm thick, matrix array of 64x64 100 mu m circular holes with 170 mu m pitch), and a 22, 60 and 122 keV point-like (1 mm diameter) radioactive sources, placed at various distances from the detector. These tests were conducted in order ...

  20. Response of a hybrid pixel detector (MEDIPIX3) to different radiation sources for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Chumacero, E. Miguel; De Celis Alonso, B.; Martínez Hernández, M. I.; Vargas, G.; Moreno Barbosa, E., E-mail: emoreno.emb@gmail.com [Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y Rio Verde, Puebla (Mexico); Moreno Barbosa, F. [Hospital General del Sur Hospital de la Mujer, Puebla (Mexico)

    2014-11-07

    The development in semiconductor CMOS technology has enabled the creation of sensitive detectors for a wide range of ionizing radiation. These devices are suitable for photon counting and can be used in imaging and tomography X-ray diagnostics. The Medipix[1] radiation detection system is a hybrid silicon pixel chip developed for particle tracking applications in High Energy Physics. Its exceptional features (high spatial and energy resolution, embedded ultra fast readout, different operation modes, etc.) make the Medipix an attractive device for applications in medical imaging. In this work the energy characterization of a third-generation Medipix chip (Medipix3) coupled to a silicon sensor is presented. We used different radiation sources (strontium 90, iron 55 and americium 241) to obtain the response curve of the hybrid detector as a function of energy. We also studied the contrast of the Medipix as a measure of pixel noise. Finally we studied the response to fluorescence X rays from different target materials (In, Pd and Cd) for the two data acquisition modes of the chip; single pixel mode and charge summing mode.

  1. Spectral and spatial resolution properties of photon counting X-ray detectors like the Medipix-Detector; Spektrale und bildgebende Eigenschaften photonenzaehlender Roentgendetektoren am Beispiel des Medipix-Detektors

    Energy Technology Data Exchange (ETDEWEB)

    Korn, A.

    2007-05-14

    The Medipix detector is a hybrid photon counting X-ray detector, consisting of an ASIC and a semiconducting layer as the sensor. This makes the Medipix a direct converting detector. A special feature of the Medipix is a signal processing circuit in every single pixel. This circuit amplifies the input signal triggered by a photon and then transforms the pulse into a digital signal. This early stage digitalisation is one of the main advantages of the detector, since no dark currents are integrated into the signal. Furthermore, the energy information of each single photon is partly preserved. The high number of pixels lends the detector a wide dynamic range, starting from single counts up to a rate of 1010 photons per cm2 and second. Apart from the many advantages, there are still some problems with the detector. Some effects lead to a deterioration of the energy resolution as well as the spatial resolution. The main reasons for this are two effects occuring in the detector, charge sharing and backscattering inside the detector. This study investigates the influence of those two effects on both the energy and spatial resolution. The physical causes of these effects are delineated and their impact on the detector output is examined. In contrast to high energy photon detectors, the repulsion of the charge carriers drifting inside the sensor must not be neglected in a detailed model of X-ray detectors with an energy range of 5 keV-200 keV. For the simulation of the Medipix using Monte Carlo simulations, the software ROSI was augmented. The added features allow a detailed simulation of the charge distribution, using the relevant physical effects that alter the distribution width during the drift towards the sensor electrodes as well further influences on the detector output, including electronical noise, threshold noise or the geometry of the detector. The measured energy and spatial resolution of several different models of Medipix is compared to the simulated

  2. Hybrid photon detectors

    CERN Document Server

    D'Ambrosio, C

    2003-01-01

    Hybrid photon detectors detect light via vacuum photocathodes and accelerate the emitted photoelectrons by an electric field towards inversely polarized silicon anodes, where they are absorbed, thus producing electron-hole pairs. These, in turn, are collected and generate electronic signals on their ohmic contacts. This review first describes the characteristic properties of the main components of hybrid photon detectors: light entrance windows, photocathodes, and silicon anodes. Then, essential relations describing the trajectories of photoelectrons in electric and magnetic fields and their backscattering from the silicon anodes are derived. Depending on their anode configurations, three families of hybrid photon detectors are presented: hybrid photomultiplier tubes with single anodes for photon counting with high sensitivity and for gamma spectroscopy; multi-anode photon detector tubes with anodes subdivided into square or hexagonal pads for position-sensitive photon detection; imaging silicon pixel array t...

  3. Pixel-level Analog-To-Digital Converters for Hybrid Pixel Detectors with energy sensitivity

    NARCIS (Netherlands)

    San Segundo Bello, D.; Nauta, Bram; Visschers, Jan

    2000-01-01

    Single-photon counting hybrid pixel detectors have shown to be a valid alternative to other types of X-ray imaging devices due to their high sensitivity, low noise, linear behavior and wide dynamic range. One important advantage of these devices is the fact that detector and readout electronics are

  4. Design of pixel-level ADCs for energy-sensitive hybrid pixel detectors

    NARCIS (Netherlands)

    San Segundo Bello, D.; Nauta, Bram; Visschers, Jan

    2000-01-01

    Single-photon counting hybrid pixel detectors have shown to be a valid alternative to other types of X-ray imaging devices due to their high sensitivity, low noise, linear behavior and wide dynamic range. One important advantage of these devices is the fact that detector and readout electronics are

  5. Femtosecond Photon-Counting Receiver

    Science.gov (United States)

    Krainak, Michael A.; Rambo, Timothy M.; Yang, Guangning; Lu, Wei; Numata, Kenji

    2016-01-01

    An optical correlation receiver is described that provides ultra-precise distance and/or time/pulse-width measurements even for weak (single photons) and short (femtosecond) optical signals. A new type of optical correlation receiver uses a fourth-order (intensity) interferometer to provide micron distance measurements even for weak (single photons) and short (femtosecond) optical signals. The optical correlator uses a low-noise-integrating detector that can resolve photon number. The correlation (range as a function of path delay) is calculated from the variance of the photon number of the difference of the optical signals on the two detectors. Our preliminary proof-of principle data (using a short-pulse diode laser transmitter) demonstrates tens of microns precision.

  6. Response functions of multi-pixel-type CdTe detector: toward development of precise material identification on diagnostic x-ray images by means of photon counting

    Science.gov (United States)

    Hayashi, Hiroaki; Asahara, Takashi; Kimoto, Natsumi; Kanazawa, Yuki; Yamakawa, Tsutomu; Yamamoto, Shuichiro; Yamasaki, Masashi; Okada, Masahiro

    2017-03-01

    Currently, an X-ray imaging system which can produced information used to identify various materials has been developed based on photon counting. It is important to estimate the response function of the detector in order to accomplish highly accurate material identification. Our aim is to simulate the response function of a CdTe detector using Monte-Carlo simulation; at this time, the transportation of incident and scattered photons and secondary produced electrons were precisely simulated without taking into consideration the charge spread in the collecting process of the produced charges (charge sharing effect). First, we set pixel sizes of 50-500μm, the minimum irradiation fields which produce equilibrium conditions were determined. Then, observed peaks in the response function were analyzed with consideration paid to the interactions between incident X-rays and the detector components, Cd and Te. The secondary produced characteristic X-rays play an important role. Accordingly ratios of full energy peak (FEP), scattering X-rays and penetrating X-rays in the calculated response functions were analyzed. When the pixel size of 200μm was used the scattered X-rays were saturated at equilibrium with relatively small fields and efficiency of FEP was kept at a high value (<50%). Finally, we demonstrated the X-ray spectrum which is folded by the response function. Even if the charge sharing effect is not completely corrected when using the electric circuit, there is a possibility that disturbed portions in the measured X-ray spectra can be corrected by using proper calibration, in which the above considerations are taken into account.

  7. A feasibility study of projection-based energy weighting based on a photon-counting detector in contrast-enhanced digital subtraction mammography: a simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sunghoon; Lee, Seungwan; Choi, Yuna; Kim, Heejoung [Yonsei University, Wonju (Korea, Republic of)

    2014-06-15

    Contrast media, such as iodine and gadolinium, are generally used in digital subtraction mammography to enhance the contrast between target and background materials. In digital subtraction mammography, where one image (with contrast medium) is subtracted from another (anatomical background) to facilitate visualization of the tumor structure, tumors can be more easily distinguished after the injection of a contrast medium. In order to have more an effective method to increase the contrast-to-noise ratio (CNR), we applied a projection-based energy-weighting method. The purpose of this study is to demonstrate the feasibility of using the projection-based energy-weighting method in digital subtraction mammography. Unlike some other previous studies, we applied the projection-based energy-weighting method to more practical mammography conditions by using the Monte Carlo method to simulate four different iodine solutions embedded in a breast phantom comprised of 50% adipose and 50% glandular tissues. We also considered an optimal tube voltage and anode/filter combination in digital iodine contrast media mammography in order to maximize the figure-of-merit (FOM). The simulated source energy was from 20 to 45 keV to prevent electronic noise and include the k-edge energy of iodine (33.2 keV). The results showed that the projection-based energy-weighting improved the CNR by factors of 1.05 - 1.86 compared to the conventionally integrated images. Consequently, the CNR of digital subtraction mammography images can be improved by using projection-based energy-weighting with photon-counting detectors.

  8. MO-FG-CAMPUS-IeP1-02: Dose Reduction in Contrast-Enhanced Digital Mammography Using a Photon-Counting Detector

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S; Kang, S; Eom, J [Konyang University, Daejeon (Korea, Republic of)

    2016-06-15

    Purpose: Photon-counting detectors (PCDs) allow multi-energy X-ray imaging without additional exposures and spectral overlap. This capability results in the improvement of accuracy of material decomposition for dual-energy X-ray imaging and the reduction of radiation dose. In this study, the PCD-based contrast-enhanced dual-energy mammography (CEDM) was compared with the conventional CDEM in terms of radiation dose, image quality and accuracy of material decomposition. Methods: A dual-energy model was designed by using Beer-Lambert’s law and rational inverse fitting function for decomposing materials from a polychromatic X-ray source. A cadmium zinc telluride (CZT)-based PCD, which has five energy thresholds, and iodine solutions included in a 3D half-cylindrical phantom, which composed of 50% glandular and 50% adipose tissues, were simulated by using a Monte Carlo simulation tool. The low- and high-energy images were obtained in accordance with the clinical exposure conditions for the conventional CDEM. Energy bins of 20–33 and 34–50 keV were defined from X-ray energy spectra simulated at 50 kVp with different dose levels for implementing the PCD-based CDEM. The dual-energy mammographic techniques were compared by means of absorbed dose, noise property and normalized root-mean-square error (NRMSE). Results: Comparing to the conventional CEDM, the iodine solutions were clearly decomposed for the PCD-based CEDM. Although the radiation dose for the PCD-based CDEM was lower than that for the conventional CEDM, the PCD-based CDEM improved the noise property and accuracy of decomposition images. Conclusion: This study demonstrates that the PCD-based CDEM allows the quantitative material decomposition, and reduces radiation dose in comparison with the conventional CDEM. Therefore, the PCD-based CDEM is able to provide useful information for detecting breast tumor and enhancing diagnostic accuracy in mammography.

  9. Influence of dead-time on detection efficiency and range performance of photon-counting laser radar that uses a Geiger-mode avalanche photodiode.

    Science.gov (United States)

    Li, Zhijian; Lai, Jiancheng; Wang, Chunyong; Yan, Wei; Li, Zhenhua

    2017-08-10

    Dead-time has a significant influence on the detection efficiency and range performance of a photon-counting laser radar system with a Geiger-mode avalanche photodiode. In this paper, a rapid universal recursive model of the detection probability of discrete time under various dead-times is proposed, which is verified with controlled parameters. Our model has the advantage of fast computing speed and unifies multi-trigger, single-trigger, and zero-dead-time models. The computing speed is 1 to 2 orders of magnitude faster than Gatt's and Zhao's models under a short dead-time condition, with relative errors less than 0.001 and 10(-14), respectively. Subsequently, the detection efficiency and range bias and precision with various dead-times are theoretically calculated and Monte Carlo simulated with different parameters. On the one hand, dead-time shorter than the end time of the target achieves better detection efficiency; however, this results in worse range performance. On the other hand, dead-time longer than the end time of the target maintains the detection efficiency at a low level but provides a better range performance. We discover that noise is the key reason for the periodic fluctuation of the detection efficiency and range performance versus different dead-times and the local optimum values of fluctuations occur when the dead-time is a few nanoseconds shorter or longer than 1, 1/2, 1/3, or even 1/4 of the end time of the target; further, this phenomenon becomes more evident when noise increases. Moreover, weaker noise level is crucial to the detection efficiency, and narrow pulse width and nearer target position in the range gate are important factors to improve precision.

  10. Imaging performance of phase-contrast breast computed tomography with synchrotron radiation and a CdTe photon-counting detector.

    Science.gov (United States)

    Sarno, A; Mettivier, G; Golosio, B; Oliva, P; Spandre, G; Di Lillo, F; Fedon, C; Longo, R; Russo, P

    2016-05-01

    Within the SYRMA-CT collaboration based at the ELETTRA synchrotron radiation (SR) facility the authors investigated the imaging performance of the phase-contrast computed tomography (CT) system dedicated to monochromatic in vivo 3D imaging of the female breast, for breast cancer diagnosis. Test objects were imaged at 38keV using monochromatic SR and a high-resolution CdTe photon-counting detector. Signal and noise performance were evaluated using modulation transfer function (MTF) and noise power spectrum. The analysis was performed on the images obtained with the application of a phase retrieval algorithm as well as on those obtained without phase retrieval. The contrast to noise ratio (CNR) and the capability of detecting test microcalcification clusters and soft masses were investigated. For a voxel size of (60μm)(3), images without phase retrieval showed higher spatial resolution (6.7mm(-1) at 10% MTF) than corresponding images with phase retrieval (2.5mm(-1)). Phase retrieval produced a reduction of the noise level and an increase of the CNR by more than one order of magnitude, compared to raw phase-contrast images. Microcalcifications with a diameter down to 130μm could be detected in both types of images. The investigation on test objects indicates that breast CT with a monochromatic SR source is technically feasible in terms of spatial resolution, image noise and contrast, for in vivo 3D imaging with a dose comparable to that of two-view mammography. Images obtained with the phase retrieval algorithm showed the best performance in the trade-off between spatial resolution and image noise. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  11. Lung nodule volume quantification and shape differentiation with an ultra-high resolution technique on a photon counting detector CT system

    Science.gov (United States)

    Zhou, W.; Montoya, J.; Gutjahr, R.; Ferrero, A.; Halaweish, A.; Kappler, S.; McCollough, C.; Leng, S.

    2017-03-01

    A new ultra high-resolution (UHR) mode has been implemented on a whole body photon counting-detector (PCD) CT system. The UHR mode has a pixel size of 0.25 mm by 0.25 mm at the iso-center, while the conventional (macro) mode is limited to 0.5 mm by 0.5 mm. A set of synthetic lung nodules (two shapes, five sizes, and two radio-densities) was scanned using both the UHR and macro modes and reconstructed with 2 reconstruction kernels (4 sets of images in total). Linear regression analysis was performed to compare measured nodule volumes from CT images to reference volumes. Surface curvature was calculated for each nodule and the full width half maximum (FWHM) of the curvature histogram was used as a shape index to differentiate sphere and star shape nodules. Receiver operating characteristic (ROC) analysis was performed and area under the ROC curve (AUC) was used as a figure of merit for the differentiation task. Results showed strong linear relationship between measured nodule volume and reference standard for both UHR and macro mode. For all nodules, volume estimation was more accurate using UHR mode with sharp kernel (S80f), with lower mean absolute percent error (MAPE) (6.5%) compared with macro mode (11.1% to 12.9%). The improvement of volume measurement from UHR mode was more evident particularly for small nodule size (3mm, 5mm), or star-shape nodules. Images from UHR mode with sharp kernel (S80f) consistently demonstrated the best performance (AUC = 0.85) when separating star from sphere shape nodules among all acquisition and reconstruction modes. Our results showed the advantages of UHR mode on a PCD CT scanner in lung nodule characterization. Various clinical applications, including quantitative imaging, can benefit substantially from this high resolution mode.

  12. A study of the talent training project management for semiconductor industry in Taiwan: the application of a hybrid data envelopment analysis approach.

    Science.gov (United States)

    Kao, Ling-Jing; Chiu, Shu-Yu; Ko, Hsien-Tang

    2014-01-01

    The purpose of this study is to evaluate the training institution performance and to improve the management of the Manpower Training Project (MTP) administered by the Semiconductor Institute in Taiwan. Much literature assesses the efficiency of an internal training program initiated by a firm, but only little literature studies the efficiency of an external training program led by government. In the study, a hybrid solution of ICA-DEA and ICA-MPI is developed for measuring the efficiency and the productivity growth of each training institution over the period. The technical efficiency change, the technological change, pure technical efficiency change, scale efficiency change, and the total factor productivity change were evaluated according to five inputs and two outputs. According to the results of the study, the training institutions can be classified by their efficiency successfully and the guidelines for the optimal level of input resources can be obtained for each inefficient training institution. The Semiconductor Institute in Taiwan can allocate budget more appropriately and establish withdrawal mechanisms for inefficient training institutions.

  13. Bio-hybrid interfaces to study neuromorphic functionalities: New multidisciplinary evidences of cell viability on poly(anyline) (PANI), a semiconductor polymer with memristive properties.

    Science.gov (United States)

    Juarez-Hernandez, Leon J; Cornella, Nicola; Pasquardini, Laura; Battistoni, Silvia; Vidalino, Laura; Vanzetti, Lia; Caponi, Silvia; Dalla Serra, Mauro; Iannotta, Salvatore; Pederzolli, Cecilia; Macchi, Paolo; Musio, Carlo

    2016-01-01

    The interfacing of artificial devices with biological systems is a challenging field that crosses several disciplines ranging from fundamental research (biophysical chemistry, neurobiology, material and surface science) to frontier technological application (nanotechnology, bioelectronics). The memristor is the fourth fundamental circuit element, whose electrical properties favor applications in signal processing, neural networks, and brain-computer interactions and it represents a new frontier for technological applications in many fields including the nanotechnologies, bioelectronics and the biosensors. Using multidisciplinary approaches, covering surface science, cell biology and electrophysiology, we successfully implemented a living bio-hybrid system constituted by cells adhering to films of poly(aniline) (PANI), a semiconductor polymer having memristive properties assembled with polyelectrolytes. Here we tested whether the PANI devices could support survivor, adhesion and differentiation of several cell lines, including the neuron-like SHSY5Y cells. Moreover, we performed electrophysiology on these cells showing that the biophysical properties are retained with differences occurring in the recorded ion currents. Taken together, the cell viability here reported is the key requirement to design and develop a reliable functional memristor-based bio-hybrid able to mimic neuronal activity and plasticity. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Influence of the Electrostatic Interaction between a Molecular Catalyst and Semiconductor on Photocatalytic Hydrogen Evolution Activity in Cobaloxime/CdS Hybrid Systems.

    Science.gov (United States)

    Xu, Yuxing; Chen, Ruotian; Li, Zhen; Li, Ailong; Han, Hongxian; Li, Can

    2017-07-12

    The influence of the electrostatic interaction on photocatalytic H 2 evolution activity in cobaloxime/cadmium sulfide (CdS) hybrid systems was studied by measuring the charges of the cobaloximes and the zeta potentials of CdS under different pH conditions (pHs 4-7). Cobaloxime/CdS hybrid systems may have potential as a valid model for the investigation of the electrostatic interaction between a molecular catalyst and semiconductor because the kinetics of methanol oxidation and the driving force of electron transfer from photoirradiated CdS to cobaloxime have little effect on the pH-dependent photocatalytic H 2 evolution activity. Our experimental results suggest that electrostatic repulsion between cobaloxime and CdS disfavors the electron transfer from CdS to cobaloxime and hence lowers the photocatalytic H 2 evolution activity. Whereas, electrostatic attraction favors the electron transfer process and enhances the photocatalytic H 2 evolution activity. However, an electrostatic attraction interaction that is too strong may accelerate both forward and backward electron transfer processes, which would reduce charge separation efficiency and lower photocatalytic H 2 evolution activity.

  15. Reducing radiation dose by application of optimized low-energy x-ray filters to K-edge imaging with a photon counting detector

    Science.gov (United States)

    Choi, Yu-Na; Lee, Seungwan; Kim, Hee-Joung

    2016-01-01

    K-edge imaging with photon counting x-ray detectors (PCXDs) can improve image quality compared with conventional energy integrating detectors. However, low-energy x-ray photons below the K-edge absorption energy of a target material do not contribute to image formation in the K-edge imaging and are likely to be completely absorbed by an object. In this study, we applied x-ray filters to the K-edge imaging with a PCXD based on cadmium zinc telluride for reducing radiation dose induced by low-energy x-ray photons. We used aluminum (Al) filters with different thicknesses as the low-energy x-ray filters and implemented the iodine K-edge imaging with an energy bin of 34-48 keV at the tube voltages of 50, 70 and 90 kVp. The effects of the low-energy x-ray filters on the K-edge imaging were investigated with respect to signal-difference-to-noise ratio (SDNR), entrance surface air kerma (ESAK) and figure of merit (FOM). The highest value of SDNR was observed in the K-edge imaging with a 2 mm Al filter, and the SDNR decreased as a function of the filter thicknesses. Compared to the K-edge imaging with a 2 mm Al filter, the ESAK was reduced by 66%, 48% and 39% in the K-edge imaging with a 12 mm Al filter for 50 kVp, 70 kVp and 90 kVp, respectively. The FOM values, which took into account the ESAK and SDNR, were maximized for 8, 6 to 8 and 4 mm Al filters at 50 kVp, 70 kVp and 90 kVp, respectively. We concluded that the use of an optimal low-energy filter thickness, which was determined by maximizing the FOM, could significantly reduce radiation dose while maintaining image quality in the K-edge imaging with the PCXD.

  16. Large Area and High Efficiency Photon Counting Imaging Detectors with High Time and Spatial Resolution for Night Time Sensing and Astronomy

    Science.gov (United States)

    Siegmund, O.; Vallerga, J.; Tremsin, A.; McPhate, J.; Frisch, H.; Elam, J.; Mane, A.; Wagner, R.; Varner, G.

    2012-09-01

    The development of large area photon counting, imaging, timing detectors with high performance has significance for applications in astronomy (such as our sensor on the SAAO SALT 10m telescope), night time remote reconnaissance, airborne/space situational awareness, and high-speed adaptive optics. Sealed tube configurations for optical/IR sensing also have applications in detection of Cherenkov light (RICH), biological single-molecule fluorescence lifetime imaging microscopy and neutron imaging applications. In open faced configurations these devices are important for UV and particle detection in space astrophysics, mass spectroscopy and many time-of flight applications. Currently available devices are limited to sizes of about 5 cm and use either conventional microchannel plates, or dynode multipliers for amplification, coupled coarse pad array readouts. Extension of these schemes to devices as large as 20 cm with high spatial resolution presents significant problems and potentially considerable cost. A collaboration (Large Area Picosecond Photon Detector) of the U. Chicago, Argonne National Laboratory, U.C. Berkeley, U. Hawaii and a number of other institutions has developed novel technologies to realize 20 cm format detectors in open face or sealed tube configurations. One critical component of this development is novel microchannel plates employing borosilicate micro-capillary arrays. The microchannel plates are based on a novel concept where the substrate is constructed from a borosilicate micro-capillary array that is made to function as a microchannel plate by deposition of resistive and secondary emissive layers using atomic layer deposition. The process is relatively inexpensive compared with conventional microchannel plates and allows very large microchannel plates to be produced with pore sizes as small as 10 microns. These provide many performance characteristics typical of conventional microchannel plates, but have been made in sizes up to 20 cm, have

  17. Energy transfer with semiconductor nanocrystals

    NARCIS (Netherlands)

    Rogach, A.L.; Klar, T.A.; Lupton, J.M.; Meijerink, A.; Feldmann, J.

    2009-01-01

    Fo¨ rster (or fluorescence) resonant energy transfer (FRET) is a powerful spectroscopic technique to study interactions, conformational and distance changes, in hybrid nanosystems. Semiconductor nanocrystals, also known as colloidal quantum dots, are highly efficient fluorophores with a strong

  18. Ballistic superconductivity in semiconductor nanowires

    NARCIS (Netherlands)

    Zhang, H.; Gül, Ö.; Conesa-Boj, S.; Nowak, M.P.; Wimmer, M.; Zuo, K.; Mourik, V.; Vries, F.K. de; Veen, J. van; Moor, M.W.A. de; Bommer, J.D.S.; Woerkom, D.J. van; Car, D.; Plissard, S.R.; Bakkers, E.P.A.M.; Quintero Pérez, M.; Cassidy, M.C.; Koelling, S.; Goswami, S.; Watanabe, K.; Taniguchi, T.; Kouwenhoven, L.P.

    2017-01-01

    Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of

  19. Semiconductor physics

    Energy Technology Data Exchange (ETDEWEB)

    Tuchkevich, V.M.; Frenkel, V.Y.

    1986-01-01

    This text is a collection of papers devoted mainly to the results of the research work in the field of semiconductors. Topics include photovoltaic solar energy conversion, interacting excitons in germanium and silicon, chalcogenide vitreous semiconductors, optical cooling of the nuclear spin system in a semiconductor, photon drag of electrons in semiconductors, dielectric losses in crystals, light scattering from heavily doped semiconductors, and the capacity of an abrupt asymmetric p-n junction.

  20. The Design and Implementation in $0.13\\mu m$ CMOS of an Algorithm Permitting Spectroscopic Imaging with High Spatial Resolution for Hybrid Pixel Detectors

    CERN Document Server

    Ballabriga, Rafael; Vilasís-Cardona, Xavier

    2009-01-01

    Advances in pixel detector technology are opening up new possibilities in many fields of science. Modern High Energy Physics (HEP) experiments use pixel detectors in tracking systems where excellent spatial resolution, precise timing and high signal-to-noise ratio are required for accurate and clean track reconstruction. Many groups are working worldwide to adapt the hybrid pixel technology to other fields such as medical X-ray radiography, protein structure analysis or neutron imaging. The Medipix3 chip is a 256x256 channel hybrid pixel detector readout chip working in Single Photon Counting Mode. It has been developed with a new front-end architecture aimed at eliminating the spectral distortion produced by charge diffusion in highly segmented semiconductor detectors. In the new architecture neighbouring pixels communicate with one another. Charges can be summed event-by-event and the incoming quantum can be assigned as a single hit to the pixel with the biggest charge deposit. In the case where incoming X-...

  1. Double Resonant Converter Topology with Fast Switching Semiconductors for Lead-Acid Battery Charger used in Hybrid Electric Locomotive

    OpenAIRE

    DE BERNARDINIS, A; BUTTERBACH, S; Lallemand, R.; JEUNESSE, A; Coquery, G.; AUBIN, PH

    2011-01-01

    This paper presents the study and experimental validation of a 9 kW lead-acid battery charger used to feed the 72V DC-Bus inside an hybrid electric locomotive demonstrator realized in the frame of the French research project PLATHEE (energy-efficient and environmentally friendly train platform). The proposed topology for the battery charger is a DC/AC/DC step-down converter structure using high frequency transformer and a double resonant series-parallel dipole. Main advantages of this topolog...

  2. High-contrast X-ray micro-radiography and micro-CT of ex-vivo soft tissue murine organs utilizing ethanol fixation and large area photon-counting detector.

    Science.gov (United States)

    Dudak, Jan; Zemlicka, Jan; Karch, Jakub; Patzelt, Matej; Mrzilkova, Jana; Zach, Petr; Hermanova, Zuzana; Kvacek, Jiri; Krejci, Frantisek

    2016-07-27

    Using dedicated contrast agents high-quality X-ray imaging of soft tissue structures with isotropic micrometre resolution has become feasible. This technique is frequently titled as virtual histology as it allows production of slices of tissue without destroying the sample. The use of contrast agents is, however, often an irreversible time-consuming procedure and despite the non-destructive principle of X-ray imaging, the sample is usually no longer usable for other research methods. In this work we present the application of recently developed large-area photon counting detector for high resolution X-ray micro-radiography and micro-tomography of whole ex-vivo ethanol-preserved mouse organs. The photon counting detectors provide dark-current-free quantum-counting operation enabling acquisition of data with virtually unlimited contrast-to-noise ratio (CNR). Thanks to the very high CNR even ethanol-only preserved soft-tissue samples without addition of any contrast agent can be visualized in great detail. As ethanol preservation is one of the standard steps of tissue fixation for histology, the presented method can open a way for widespread use of micro-CT with all its advantages for routine 3D non-destructive soft-tissue visualisation.

  3. Semiconductor statistics

    CERN Document Server

    Blakemore, J S

    1987-01-01

    In-depth exploration of the implications of carrier populations and Fermi energies examines distribution of electrons in energy bands and impurity levels of semiconductors. Also: kinetics of semiconductors containing excess carriers, particularly in terms of trapping, excitation, and recombination.

  4. Semiconductor physics

    CERN Document Server

    Böer, Karl W

    2018-01-01

    This handbook gives a complete survey of the important topics and results in semiconductor physics. It addresses every fundamental principle and most research topics and areas of application in the field of semiconductor physics. Comprehensive information is provided on crystalline bulk and low-dimensional as well as amporphous semiconductors, including optical, transport, and dynamic properties.

  5. Hybrid Double Quantum Dots

    DEFF Research Database (Denmark)

    Sherman, D.; Yodh, J. S.; Albrecht, S. M.

    2016-01-01

    Epitaxial semiconductor-superconductor hybrid materials are an excellent basis for studying mesoscopic and topological superconductivity, as the semiconductor inherits a hard superconducting gap while retaining tunable carrier density. Here, we investigate double-quantum-dot devices made from InA...... that the individual dots host weakly hybridized Majorana modes....

  6. Estimation of Basis Line-Integrals in a Spectral Distortion-Modeled Photon Counting Detector Using Low-Rank Approximation-Based X-Ray Transmittance Modeling: K-Edge Imaging Application.

    Science.gov (United States)

    Lee, Okkyun; Kappler, Steffen; Polster, Christoph; Taguchi, Katsuyuki

    2017-11-01

    Photon counting detectors (PCDs) provide multiple energy-dependent measurements for estimating basis line-integrals. However, the measured spectrum is distorted from the spectral response effect (SRE) via charge sharing, K-fluorescence emission, and so on. Thus, in order to avoid bias and artifacts in images, the SRE needs to be compensated. For this purpose, we recently developed a computationally efficient three-step algorithm for PCD-CT without contrast agents by approximating smooth X-ray transmittance using low-order polynomial bases. It compensated the SRE by incorporating the SRE model in a linearized estimation process and achieved nearly the minimum variance and unbiased (MVU) estimator. In this paper, we extend the three-step algorithm to K-edge imaging applications by designing optimal bases using a low-rank approximation to model X-ray transmittances with arbitrary shapes (i.e., smooth without the K-edge or discontinuous with the K-edge). The bases can be used to approximate the X-ray transmittance and to linearize the PCD measurement modeling and then the three-step estimator can be derived as in the previous approach: estimating the x-ray transmittance in the first step, estimating basis line-integrals including that of the contrast agent in the second step, and correcting for a bias in the third step. We demonstrate that the proposed method is more accurate and stable than the low-order polynomial-based approaches with extensive simulation studies using gadolinium for the K-edge imaging application. We also demonstrate that the proposed method achieves nearly MVU estimator, and is more stable than the conventional maximum likelihood estimator in high attenuation cases with fewer photon counts.

  7. Gamma spectroscopy and optoelectronic imaging with hybrid photon detector

    CERN Document Server

    D'Ambrosio, C; Piedigrossi, D; Rosso, E; Cenceelli, V; De Notaristefani, F; Masini, Gérald; Puertolas, D; Cindolo, F; Mares, J A; Nikl, M; Abreu, M; Rato-Mendes, P; Sousa, P

    2003-01-01

    Hybrid Photon Detectors (HPD) detect light via photocathodes and accelerate the emitted photoelectrons by an electric field towards silicon PIN-anodes, where they are absorbed and generate electronic signals. We have developed two specific types of HPDs: (1) Hybrid photomultiplier tubes for photon counting and gamma spectroscopy; (2) Imaging silicon pixel array tubes for optoelectronic cameras. This paper will illustrate the main achievements, which we obtained in the last years, and will describe and discuss our present main R&D efforts, in particular, in the biomedical imaging field. (27 refs).

  8. Epitaxy of semiconductor-superconductor nanowires

    DEFF Research Database (Denmark)

    Krogstrup, P.; Ziino, N.L.B.; Chang, W.

    2015-01-01

    Controlling the properties of semiconductor/metal interfaces is a powerful method for designing functionality and improving the performance of electrical devices. Recently semiconductor/superconductor hybrids have appeared as an important example where the atomic scale uniformity of the interface...

  9. Semiconductor spintronics

    CERN Document Server

    Xia, Jianbai; Chang, Kai

    2012-01-01

    Semiconductor Spintronics, as an emerging research discipline and an important advanced field in physics, has developed quickly and obtained fruitful results in recent decades. This volume is the first monograph summarizing the physical foundation and the experimental results obtained in this field. With the culmination of the authors' extensive working experiences, this book presents the developing history of semiconductor spintronics, its basic concepts and theories, experimental results, and the prospected future development. This unique book intends to provide a systematic and modern foundation for semiconductor spintronics aimed at researchers, professors, post-doctorates, and graduate students, and to help them master the overall knowledge of spintronics.

  10. In-laboratory ALOHA mid-infrared up-conversion interferometer in the photon counting regime at λ = 3.39 μm

    Science.gov (United States)

    Szemendera, L.; Grossard, L.; Delage, L.; Reynaud, F.

    2017-07-01

    Astronomical Light Optical Hybrid Analysis (ALOHA@3.39 μm) is a new instrumental concept designed for high angular resolution astronomical imaging in the L band. The originality of our experimental device is to include a frequency conversion process in each arm of the interferometer that frequency shifts the mid-infrared signal to the near-infrared domain. This method relaxes the stringent limitations due to the thermal noise background radiated by the instrument itself. The aim of this paper is to estimate the current sensitivity limit of the instrument and validate the ability to provide calibrated contrasts with a quasi-monochromatic signal. We demonstrate the possibility to measure fringe contrasts greater than 94.5 per cent with a signal-to-noise ratio close to 7. The flux level at the input of each arm of the interferometer is then equal to 100 fw. This would correspond to a zero magnitude star in the L band for a 1 m2 telescope surface and a 3 nm converted spectral bandwidth.

  11. Macroporous Semiconductors

    Directory of Open Access Journals (Sweden)

    Helmut Föll

    2010-05-01

    Full Text Available Pores in single crystalline semiconductors come in many forms (e.g., pore sizes from 2 nm to > 10 µm; morphologies from perfect pore crystal to fractal and exhibit many unique properties directly or as nanocompounds if the pores are filled. The various kinds of pores obtained in semiconductors like Ge, Si, III-V, and II-VI compound semiconductors are systematically reviewed, emphasizing macropores. Essentials of pore formation mechanisms will be discussed, focusing on differences and some open questions but in particular on common properties. Possible applications of porous semiconductors, including for example high explosives, high efficiency electrodes for Li ion batteries, drug delivery systems, solar cells, thermoelectric elements and many novel electronic, optical or sensor devices, will be introduced and discussed.

  12. Retraction of “Accurate Prediction of Essential Fundamental Properties for Semiconductors Used in Solar-Energy Conversion Devices from Range-Separated Hybrid Density Functional Theory”

    KAUST Repository

    Harb, Moussab

    2016-03-08

    The author retracts this article due to similarities with a previously published article by Le Bahers, T.; Rerat, M.; Sautet, ́ P. Semiconductors Used in Photovoltaic and Photocatalytic Devices: Assessing Fundamental Properties from DFT. J. Phys. Chem. C 2014, 118 (12), 5997−6008 (DOI: 10.1021/jp409724c).

  13. Semiconductor statistics

    CERN Document Server

    Blakemore, J S

    1962-01-01

    Semiconductor Statistics presents statistics aimed at complementing existing books on the relationships between carrier densities and transport effects. The book is divided into two parts. Part I provides introductory material on the electron theory of solids, and then discusses carrier statistics for semiconductors in thermal equilibrium. Of course a solid cannot be in true thermodynamic equilibrium if any electrical current is passed; but when currents are reasonably small the distribution function is but little perturbed, and the carrier distribution for such a """"quasi-equilibrium"""" co

  14. Semiconductor electrochemistry

    CERN Document Server

    Memming, Rüdiger

    2015-01-01

    Providing both an introduction and an up-to-date survey of the entire field, this text captivates the reader with its clear style and inspiring, yet solid presentation. The significantly expanded second edition of this milestone work is supplemented by a completely new chapter on the hot topic of nanoparticles and includes the latest insights into the deposition of dye layers on semiconductor electrodes. In his monograph, the acknowledged expert Professor Memming primarily addresses physical and electrochemists, but materials scientists, physicists, and engineers dealing with semiconductor technology and its applications will also benefit greatly from the contents.

  15. Oxide semiconductors

    CERN Document Server

    Svensson, Bengt G; Jagadish, Chennupati

    2013-01-01

    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scient

  16. Survey of cryogenic semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Talarico, L.J.; McKeever, J.W.

    1996-04-01

    Improved reliability and electronic performance can be achieved in a system operated at cryogenic temperatures because of the reduction in mechanical insult and in disruptive effects of thermal energy on electronic devices. Continuing discoveries of new superconductors with ever increasing values of T{sub c} above that of liquid nitrogen temperature (LNT) have provided incentive for developing semiconductor electronic systems that may also operate in the superconductor`s liquid nitrogen bath. Because of the interest in high-temperature superconductor (HTS) devices, liquid nitrogen is the cryogen of choice and LNT is the temperature on which this review is focused. The purpose of this survey is to locate and assemble published information comparing the room temperature (298 K), performance of commercially available conventional and hybrid semiconductor device with their performance at LNT (77K), to help establish their candidacy as cryogenic electronic devices specifically for use at LNT. The approach to gathering information for this survey included the following activities. Periodicals and proceedings were searched for information on the behavior of semiconductor devices at LNT. Telephone calls were made to representatives of semiconductor industries, to semiconductor subcontractors, to university faculty members prominent for their research in the area of cryogenic semiconductors, and to representatives of the National Aeronautics and Space Administration (NASA) and NASA subcontractors. The sources and contacts are listed with their responses in the introduction, and a list of references appears at the end of the survey.

  17. Photon counts statistics in leukocyte cell dynamics

    NARCIS (Netherlands)

    Wijk, E. van; Greef, J. van der; Wijk, R. van

    2011-01-01

    In the present experiment ultra-weak photon emission/ chemiluminescence from isolated neutrophils was recorded. It is associated with the production of reactive oxygen species (ROS) in the "respiratory burst" process which can be activated by PMA (Phorbol 12-Myristate 13-Acetate). Commonly, the

  18. Ultrafast spectroscopy of semiconductors and semiconductor nanostructures

    CERN Document Server

    Shah, Jagdeep

    1996-01-01

    Ultrafast Spectroscopy of Semiconductors and Semiconductor Nanostructures Ultrafast spectroscopy of semiconductors is currently one of the most exciting areas of research in condensed-matter physics Remarkable recent progress in the generation of tunable femtosecond pulses has allowed direct investigation of the most fundamental dynamical processes in semiconductors This monograph presents some of the most striking recent advances in the field of ultrafast spectroscopy of semiconductors and their nanostructures After a brief overview of the basic concepts and of the recent advances in the techniques of ultrashort pulse generation and ultrafast spectroscopy, it discusses the physics of relaxation, tunneling and transport dynamics in semiconductors and semiconductor nanostructures following excitation by femtosecond laser pulses

  19. Hybrid pn-junction solar cells based on layers of inorganic nanocrystals and organic semiconductors: optimization of layer thickness by considering the width of the depletion region.

    Science.gov (United States)

    Saha, Sudip K; Guchhait, Asim; Pal, Amlan J

    2014-03-07

    We report the formation and characterization of hybrid pn-junction solar cells based on a layer of copper diffused silver indium disulfide (AgInS2@Cu) nanoparticles and another layer of copper phthalocyanine (CuPc) molecules. With copper diffusion in the nanocrystals, their optical absorption and hence the activity of the hybrid pn-junction solar cells was extended towards the near-IR region. To decrease the particle-to-particle separation for improved carrier transport through the inorganic layer, we replaced the long-chain ligands of copper-diffused nanocrystals in each monolayer with short-ones. Under illumination, the hybrid pn-junctions yielded a higher short-circuit current as compared to the combined contribution of the Schottky junctions based on the components. A wider depletion region at the interface between the two active layers in the pn-junction device as compared to that of the Schottky junctions has been considered to analyze the results. Capacitance-voltage characteristics under a dark condition supported such a hypothesis. We also determined the width of the depletion region in the two layers separately so that a pn-junction could be formed with a tailored thickness of the two materials. Such a "fully-depleted" device resulted in an improved photovoltaic performance, primarily due to lessening of the internal resistance of the hybrid pn-junction solar cells.

  20. Magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bihler, Christoph

    2009-04-15

    In this thesis we investigated in detail the properties of Ga{sub 1-x}Mn{sub x}As, Ga{sub 1-x}Mn{sub x}P, and Ga{sub 1-x}Mn{sub x}N dilute magnetic semiconductor thin films with a focus on the magnetic anisotropy and the changes of their properties upon hydrogenation. We applied two complementary spectroscopic techniques to address the position of H in magnetic semiconductors: (i) Electron paramagnetic resonance, which provides direct information on the symmetry of the crystal field of the Mn{sup 2+} atoms and (ii) x-ray absorption fine structure analysis which allows to probe the local crystallographic neighborhood of the absorbing Mn atom via analysing the fine structure at the Mn K absorption edge. Finally, we discussed the obstacles that have to be overcome to achieve Curie temperatures above the current maximum in Ga{sub 1-x}Mn{sub x}As of 185 K. Here, we outlined in detail the generic problem of the formation of precipitates at the example of Ge:MN. (orig.)

  1. Power semiconductors

    CERN Document Server

    Kubát, M

    1984-01-01

    The book contains a summary of our knowledge of power semiconductor structures. It presents first a short historic introduction (Chap. I) as well as a brief selection of facts from solid state physics, in particular those related to power semiconductors (Chap. 2). The book deals with diode structures in Chap. 3. In addition to fundamental facts in pn-junction theory, the book covers mainly the important processes of power structures. It describes the emitter efficiency and function of microleaks (shunts). the p +p and n + n junctions, and in particular the recent theory of the pin, pvn and p1tn junctions, whose role appears to be decisive for the forward mode not only of diode structures but also of more complex ones. For power diode structures the reverse mode is the decisive factor in pn-junction breakdown theory. The presentation given here uses engineering features (the multiplication factor M and the experimentally detected laws for the volume and surface of crystals), which condenses the presentation an...

  2. Semiconductor Laser Measurements Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Semiconductor Laser Measurements Laboratory is equipped to investigate and characterize the lasing properties of semiconductor diode lasers. Lasing features such...

  3. Hybrid spectral CT reconstruction

    Science.gov (United States)

    Clark, Darin P.

    2017-01-01

    Current photon counting x-ray detector (PCD) technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID). In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM). Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with a spectral

  4. Hybrid spectral CT reconstruction.

    Directory of Open Access Journals (Sweden)

    Darin P Clark

    Full Text Available Current photon counting x-ray detector (PCD technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID. In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM. Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with

  5. Hybrid spectral CT reconstruction.

    Science.gov (United States)

    Clark, Darin P; Badea, Cristian T

    2017-01-01

    Current photon counting x-ray detector (PCD) technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID). In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM). Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with a spectral

  6. Ballistic superconductivity in semiconductor nanowires.

    Science.gov (United States)

    Zhang, Hao; Gül, Önder; Conesa-Boj, Sonia; Nowak, Michał P; Wimmer, Michael; Zuo, Kun; Mourik, Vincent; de Vries, Folkert K; van Veen, Jasper; de Moor, Michiel W A; Bommer, Jouri D S; van Woerkom, David J; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P A M; Quintero-Pérez, Marina; Cassidy, Maja C; Koelling, Sebastian; Goswami, Srijit; Watanabe, Kenji; Taniguchi, Takashi; Kouwenhoven, Leo P

    2017-07-06

    Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of superconductors with the possibility to control charges down to a single electron. These advances brought semiconductor nanowires to the forefront of efforts to realize topological superconductivity and Majorana modes. A prime challenge to benefit from the topological properties of Majoranas is to reduce the disorder in hybrid nanowire devices. Here we show ballistic superconductivity in InSb semiconductor nanowires. Our structural and chemical analyses demonstrate a high-quality interface between the nanowire and a NbTiN superconductor that enables ballistic transport. This is manifested by a quantized conductance for normal carriers, a strongly enhanced conductance for Andreev-reflecting carriers, and an induced hard gap with a significantly reduced density of states. These results pave the way for disorder-free Majorana devices.

  7. Revenue sharing in semiconductor industry supply chain ...

    Indian Academy of Sciences (India)

    This paper defines cooperation as the process of coordinating the objectives and activities of supply chain (SC) members. It also focuses on cooperation as a solution for hybrid coordination mechanism to form the basis for semiconductor industry supply chain management. In the complex and competitive environment of ...

  8. A Semiconductor Nanowire-Based Superconducting Qubit

    DEFF Research Database (Denmark)

    Larsen, T. W.; Petersson, K. D.; Kuemmeth, F.

    2015-01-01

    We introduce a hybrid qubit based on a semiconductor nanowire with an epitaxially grown superconductor layer. Josephson energy of the transmon-like device ("gatemon") is controlled by an electrostatic gate that depletes carriers in a semiconducting weak link region. Strong coupling to an on...

  9. Fundamentals of semiconductor devices

    CERN Document Server

    Lindmayer, Joseph

    1965-01-01

    Semiconductor properties ; semiconductor junctions or diodes ; transistor fundamentals ; inhomogeneous impurity distributions, drift or graded-base transistors ; high-frequency properties of transistors ; band structure of semiconductors ; high current densities and mechanisms of carrier transport ; transistor transient response and recombination processes ; surfaces, field-effect transistors, and composite junctions ; additional semiconductor characteristics ; additional semiconductor devices and microcircuits ; more metal, insulator, and semiconductor combinations for devices ; four-pole parameters and configuration rotation ; four-poles of combined networks and devices ; equivalent circuits ; the error function and its properties ; Fermi-Dirac statistics ; useful physical constants.

  10. Reserve current analysis in semiconductor insulator semiconductor ...

    African Journals Online (AJOL)

    Reserve current analysis in semiconductor insulator semiconductor (SIS) solar cells. H Yakubu, PK Mensah. Abstract. No Abstract. Journal of the Ghana Association Vol. 2 (3) 1999: pp. 1-4. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

  11. Handbook of spintronic semiconductors

    CERN Document Server

    Chen, Weimin

    2010-01-01

    Offers a review of the field of spintronic semiconductors. This book covers a range of topics, including growth and basic physical properties of diluted magnetic semiconductors based on II-VI, III-V and IV semiconductors, developments in theory and experimental techniques and potential device applications.

  12. Development and characterization of a 3D CdTe:Cl semiconductor detector for medical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Avenel, Marie-Laure [CEA, LETI, MINATEC-Campus, 17 rue des Martyrs, F-38054 Grenoble (France); Farcage, Daniel [CEA, DEN-DPC, F-91191 Gif Sur Yvette (France); Ruat, Marie; Verger, Loieck [CEA, LETI, MINATEC-Campus, 17 rue des Martyrs, F-38054 Grenoble (France); Gros d' Aillon, Eric, E-mail: eric.grosdaillon@cea.fr [CEA, LETI, MINATEC-Campus, 17 rue des Martyrs, F-38054 Grenoble (France)

    2012-04-11

    Conventional semiconductor radiation detectors for medical imaging use either a planar structure or a pixelated structure. These structures exhibit a natural trade-off between the absorption of incident photons and the collection of free charge carriers, resulting in a limited choice of detection materials. Such a trade-off can be avoided using a 3D structure in which electrodes are drilled into the detection volume. A prototype 3D semiconductor detector has been developed, using CdTe:Cl. A laser drilling technique was used to create electrodes in the volume of the material. The electrodes were contacted using electroless Au deposition. The manufacturing process and the first spectrometric results obtained with {sup 241}Am and {sup 57}Co irradiation are presented below. Synchrotron X-ray irradiation was also performed at the European Synchrotron Radiation Facility (ESRF) at an incident energy of 60 keV. An individual photon-counting ability was exhibited. These results will be used as a proof of concept for investigating 3D detectors in the medical-imaging energy range.

  13. Rhombohedrel Hybrid Crystal Semiconductor Device Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA Langley has succeeded in growing a rhombohedrally oriented single crystal SiGe on sapphire substrate. This opens up new challenges in micro-electronics. Since...

  14. Semiconductor Physical Electronics

    CERN Document Server

    Li, Sheng

    2006-01-01

    Semiconductor Physical Electronics, Second Edition, provides comprehensive coverage of fundamental semiconductor physics that is essential to an understanding of the physical and operational principles of a wide variety of semiconductor electronic and optoelectronic devices. This text presents a unified and balanced treatment of the physics, characterization, and applications of semiconductor materials and devices for physicists and material scientists who need further exposure to semiconductor and photonic devices, and for device engineers who need additional background on the underlying physical principles. This updated and revised second edition reflects advances in semicondutor technologies over the past decade, including many new semiconductor devices that have emerged and entered into the marketplace. It is suitable for graduate students in electrical engineering, materials science, physics, and chemical engineering, and as a general reference for processing and device engineers working in the semicondi...

  15. Semiconductor devices physics and technology

    CERN Document Server

    Sze, Simon

    2012-01-01

    Semiconductor Devices: Physics and Technology, Third Edition is an introduction to the physical principles of modern semiconductor devices and their advanced fabrication technology. It begins with a brief historical review of major devices and key technologies and is then divided into three sections: semiconductor material properties, physics of semiconductor devices and processing technology to fabricate these semiconductor devices.

  16. Semiconductor Electrical Measurements Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Semiconductor Electrical Measurements Laboratory is a research laboratory which complements the Optical Measurements Laboratory. The laboratory provides for Hall...

  17. Basic semiconductor physics

    CERN Document Server

    Hamaguchi, Chihiro

    2001-01-01

    This book presents a detailed description of the basic physics of semiconductors. All the important equations describing the properties of these materials are derived without the help of other textbooks. The reader is assumed to have only a basic command of mathematics and some elementary semiconductor physics. The text covers a wide range of important semiconductor phenomena, from the simple to the advanced. Examples include recent progress in semiconductor quantum structures such as two-dimensional electron-gas systems, ballistic transport, the quantum Hall effect, the Landauer formula, the Coulomb blockade and the single-electron transistor.

  18. Localized Surface Plasmon Resonance in Semiconductor Nanocrystals.

    Science.gov (United States)

    Agrawal, Ankit; Cho, Shin Hum; Zandi, Omid; Ghosh, Sandeep; Johns, Robert W; Milliron, Delia J

    2018-02-05

    Localized surface plasmon resonance (LSPR) in semiconductor nanocrystals (NCs) that results in resonant absorption, scattering, and near field enhancement around the NC can be tuned across a wide optical spectral range from visible to far-infrared by synthetically varying doping level, and post synthetically via chemical oxidation and reduction, photochemical control, and electrochemical control. In this review, we will discuss the fundamental electromagnetic dynamics governing light matter interaction in plasmonic semiconductor NCs and the realization of various distinctive physical properties made possible by the advancement of colloidal synthesis routes to such NCs. Here, we will illustrate how free carrier dielectric properties are induced in various semiconductor materials including metal oxides, metal chalcogenides, metal nitrides, silicon, and other materials. We will highlight the applicability and limitations of the Drude model as applied to semiconductors considering the complex band structures and crystal structures that predominate and quantum effects that emerge at nonclassical sizes. We will also emphasize the impact of dopant hybridization with bands of the host lattice as well as the interplay of shape and crystal structure in determining the LSPR characteristics of semiconductor NCs. To illustrate the discussion regarding both physical and synthetic aspects of LSPR-active NCs, we will focus on metal oxides with substantial consideration also of copper chalcogenide NCs, with select examples drawn from the literature on other doped semiconductor materials. Furthermore, we will discuss the promise that LSPR in doped semiconductor NCs holds for a wide range of applications such as infrared spectroscopy, energy-saving technologies like smart windows and waste heat management, biomedical applications including therapy and imaging, and optical applications like two photon upconversion, enhanced luminesence, and infrared metasurfaces.

  19. Semiconductor radiation detectors. Device physics

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, G. [Max-Planck-Institut fuer Physik, Muenchen (Germany)]|[Max-Planck-Institut fuer Extraterrestrische Physik, Garching (Germany). Semiconductor Lab.

    1999-07-01

    The following topics were dealt with: semiconductor radiation detectors, basic semiconductor structures, semiconductors, energy measurement, radiation-level measurement, position measurement, electronics of the readout function, detectors with intrinsic amplification, detector technology, device stability, radiation hardness and device simulation.

  20. Comparison of three types of XPAD3.2/CdTe single chip hybrids for hard X-ray applications in material science and biomedical imaging

    Science.gov (United States)

    Buton, C.; Dawiec, A.; Graber-Bolis, J.; Arnaud, K.; Bérar, J. F.; Blanc, N.; Boudet, N.; Clémens, J. C.; Debarbieux, F.; Delpierre, P.; Dinkespiler, B.; Gastaldi, T.; Hustache, S.; Morel, C.; Pangaud, P.; Perez-Ponce, H.; Vigeolas, E.

    2014-09-01

    The CHIPSPECT consortium aims at building a large multi-modules CdTe based photon counting detector for hard X-ray applications. For this purpose, we tested nine XPAD3.2 single chip hybrids in various configurations (i.e. Ohmic vs. Schottky contacts or electrons vs. holes collection mode) in order to select the most performing and best suited configuration for our experimental requirements. Measurements have been done using both X-ray synchrotron beams and 241Am source. Preliminary results on the image quality, calibration, stability, homogeneity and linearity of the different types of detectors are presented.

  1. Comparison of three types of XPAD3.2/CdTe single chip hybrids for hard X-ray applications in material science and biomedical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Buton, C., E-mail: clement.buton@synchrotron-soleil.fr [Synchrotron SOLEIL, L´Orme des Merisiers, Saint-Aubin — BP 48 91192, Gif-sur-Yvette Cedex (France); Dawiec, A. [Synchrotron SOLEIL, L´Orme des Merisiers, Saint-Aubin — BP 48 91192, Gif-sur-Yvette Cedex (France); Graber-Bolis, J.; Arnaud, K. [CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille (France); Bérar, J.F.; Blanc, N.; Boudet, N. [Université Grenoble Alpes, Institut NÉEL, F-38042 Grenoble (France); CNRS, Institut NÉEL, F-38042 Grenoble (France); Clémens, J.C.; Debarbieux, F. [CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille (France); Delpierre, P.; Dinkespiler, B. [imXPAD SAS — Espace Mistral, Athélia IV, 297 avenue du Mistral, 13600 La Ciotat (France); Gastaldi, T. [CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille (France); Hustache, S. [Synchrotron SOLEIL, L´Orme des Merisiers, Saint-Aubin — BP 48 91192, Gif-sur-Yvette Cedex (France); Morel, C.; Pangaud, P. [CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille (France); Perez-Ponce, H. [imXPAD SAS — Espace Mistral, Athélia IV, 297 avenue du Mistral, 13600 La Ciotat (France); Vigeolas, E. [CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille (France)

    2014-09-11

    The CHIPSPECT consortium aims at building a large multi-modules CdTe based photon counting detector for hard X-ray applications. For this purpose, we tested nine XPAD3.2 single chip hybrids in various configurations (i.e. Ohmic vs. Schottky contacts or electrons vs. holes collection mode) in order to select the most performing and best suited configuration for our experimental requirements. Measurements have been done using both X-ray synchrotron beams and {sup 241}Am source. Preliminary results on the image quality, calibration, stability, homogeneity and linearity of the different types of detectors are presented.

  2. Semiconductors data handbook

    CERN Document Server

    Madelung, Otfried

    2004-01-01

    This volume Semiconductors: Data Handbook contains frequently used data from the corresponding larger Landolt-Börnstein handbooks in a low price book for the individual scientist working in the laboratory. The Handbook contain important information about a large number of semiconductors

  3. High energy semiconductor switch

    Science.gov (United States)

    Risberg, R. L.

    1989-02-01

    The objective was a controller for electric motors. By operating standard Nema B induction motors at variable speed a great deal of energy is saved. This is especially true in pumping and air conditioning applications. To allow wider use of variable speed AC drives, and to provide improved performance, a better semiconductor switch was sought. This was termed the High Energy Semiconductor Switch.

  4. Semiconductor radiation detection systems

    CERN Document Server

    2010-01-01

    Covers research in semiconductor detector and integrated circuit design in the context of medical imaging using ionizing radiation. This book explores other applications of semiconductor radiation detection systems in security applications such as luggage scanning, dirty bomb detection and border control.

  5. Semiconductor Research Experimental Techniques

    CERN Document Server

    Balkan, Naci

    2012-01-01

    The book describes the fundamentals, latest developments and use of key experimental techniques for semiconductor research. It explains the application potential of various analytical methods and discusses the opportunities to apply particular analytical techniques to study novel semiconductor compounds, such as dilute nitride alloys. The emphasis is on the technique rather than on the particular system studied.

  6. Spin physics in semiconductors

    CERN Document Server

    Dyakonov, Mikhail I

    2008-01-01

    This book describes beautiful optical and transport phenomena related to the electron and nuclear spins in semiconductors with emphasis on a clear presentation of the physics involved. Recent results on quantum wells and quantum dots are reviewed. The book is intended for students and researchers in the fields of semiconductor physics and nanoelectronics.

  7. Compound Semiconductor Radiation Detectors

    CERN Document Server

    Owens, Alan

    2012-01-01

    Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

  8. Spectral CT modeling and reconstruction with hybrid detectors in dynamic-threshold-based counting and integrating modes.

    Science.gov (United States)

    Li, Liang; Chen, Zhiqiang; Cong, Wenxiang; Wang, Ge

    2015-03-01

    Spectral CT with photon counting detectors can significantly improve CT performance by reducing image noise and dose, increasing contrast resolution and material specificity, as well as enabling functional and molecular imaging with existing and emerging probes. However, the current photon counting detector architecture is difficult to balance the number of energy bins and the statistical noise in each energy bin. Moreover, the hardware support for multi-energy bins demands a complex circuit which is expensive. In this paper, we promote a new scheme known as hybrid detectors that combine the dynamic-threshold-based counting and integrating modes. In this scheme, an energy threshold can be dynamically changed during a spectral CT scan, which can be considered as compressive sensing along the spectral dimension. By doing so, the number of energy bins can be retrospectively specified, even in a spatially varying fashion. To establish the feasibility and merits of such hybrid detectors, we develop a tensor-based PRISM algorithm to reconstruct a spectral CT image from dynamic dual-energy data, and perform experiments with simulated and real data, producing very promising results.

  9. Wide-Bandgap Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chinthavali, M.S.

    2005-11-22

    . With the advent of the use of SiC devices it is imperative that models of these be made available in commercial simulators. This enables power electronic designers to simulate their designs for various test conditions prior to fabrication. To build an accurate transistor-level model of a power electronic system such as an inverter, the first step is to characterize the semiconductor devices that are present in the system. Suitable test beds need to be built for each device to precisely test the devices and obtain relevant data that can be used for modeling. This includes careful characterization of the parasitic elements so as to emulate the test setup as closely as possible in simulations. This report is arranged as follows: Chapter 2--The testing and characterization of several diodes and power switches is presented. Chapter 3--A 55-kW hybrid inverter (Si insulated gate bipolar transistor--SiC Schottky diodes) device models and test results are presented. A detailed description of the various test setups followed by the parameter extraction, modeling, and simulation study of the inverter performance is presented. Chapter 4--A 7.5-kW all-SiC inverter (SiC junction field effect transistors (JFET)--SiC Schottky diodes) was built and tested. The models built in Saber were validated using the test data and the models were used in system applications in the Saber simulator. The simulation results and a comparison of the data from the prototype tests are discussed in this chapter. Chapter 5--The duration test results of devices utilized in buck converters undergoing reliability testing are presented.

  10. Optoelectronic properties of semiconductor nanostructures

    Science.gov (United States)

    Maher, Kristin Nicole

    barriers at the metal-semiconductor interface at low bias, the potential profile of the device at high bias cannot be described using an ideal back-to-back Schottky diode model. Instead, accumulation of charge carriers gives rise to an abrupt potential drop near the positively-biased electrode where EL is observed. This large potential drop leads to impact ionization, producing electronhole pairs that recombine to emit light. Preliminary work on CdS/CdSe bilayer nanowires contacted individually by the conducting polymer poly(3-hexylthiophene) (P3HT) indicates that this hybrid structure may provide a route to light emission with a narrow spectral distribution by inducing band-edge recombination of carriers. Because of widespread interest in the photovoltaic properties of nanocrystal/P3HT devices, initial photocurrent measurements on the nanowire/P3HT interface are also being explored. These measurements may provide a means to study charge separation efficiencies, which are difficult to determine in ensemble devices.

  11. Physics of semiconductor lasers

    CERN Document Server

    Mroziewicz, B; Nakwaski, W

    2013-01-01

    Written for readers who have some background in solid state physics but do not necessarily possess any knowledge of semiconductor lasers, this book provides a comprehensive and concise account of fundamental semiconductor laser physics, technology and properties. The principles of operation of these lasers are therefore discussed in detail with the interrelations between their design and optical, electrical and thermal properties. The relative merits of a large number of laser structures and their parameters are described to acquaint the reader with the various aspects of the semiconductor l

  12. Defects in semiconductors

    CERN Document Server

    Romano, Lucia; Jagadish, Chennupati

    2015-01-01

    This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoret

  13. Semiconductors bonds and bands

    CERN Document Server

    Ferry, David K

    2013-01-01

    As we settle into this second decade of the twenty-first century, it is evident that the advances in micro-electronics have truly revolutionized our day-to-day lifestyle. The technology is built upon semiconductors, materials in which the band gap has been engineered for special values suitable to the particular application. This book, written specifically for a one semester course for graduate students, provides a thorough understanding of the key solid state physics of semiconductors. It describes how quantum mechanics gives semiconductors unique properties that enabled the micro-electronics revolution, and sustain the ever-growing importance of this revolution.

  14. Spin physics in semiconductors

    CERN Document Server

    2017-01-01

    This book offers an extensive introduction to the extremely rich and intriguing field of spin-related phenomena in semiconductors. In this second edition, all chapters have been updated to include the latest experimental and theoretical research. Furthermore, it covers the entire field: bulk semiconductors, two-dimensional semiconductor structures, quantum dots, optical and electric effects, spin-related effects, electron-nuclei spin interactions, Spin Hall effect, spin torques, etc. Thanks to its self-contained style, the book is ideally suited for graduate students and researchers new to the field.

  15. Compact semiconductor lasers

    CERN Document Server

    Yu, Siyuan; Lourtioz, Jean-Michel

    2014-01-01

    This book brings together in a single volume a unique contribution by the top experts around the world in the field of compact semiconductor lasers to provide a comprehensive description and analysis of the current status as well as future directions in the field of micro- and nano-scale semiconductor lasers. It is organized according to the various forms of micro- or nano-laser cavity configurations with each chapter discussing key technical issues, including semiconductor carrier recombination processes and optical gain dynamics, photonic confinement behavior and output coupling mechanisms, carrier transport considerations relevant to the injection process, and emission mode control. Required reading for those working in and researching the area of semiconductors lasers and micro-electronics.

  16. Defects in semiconductor nanostructures

    Science.gov (United States)

    Singh, Vijay A.; Harbola, Manoj K.; Pathak, Praveen

    2008-02-01

    Impurities play a pivotal role in semiconductors. One part in a million of phosphorous in silicon alters the conductivity of the latter by several orders of magnitude. Indeed, the information age is possible only because of the unique role of shallow impurities in semiconductors. Although work in semiconductor nanostructures (SN) has been in progress for the past two decades, the role of impurities in them has been only sketchily studied. We outline theoretical approaches to the electronic structure of shallow impurities in SN and discuss their limitations. We find that shallow levels undergo a SHADES (SHAllow-DEep-Shallow) transition as the SN size is decreased. This occurs because of the combined effect of quantum confinement and reduced dielectric constant in SN. Level splitting is pronounced and this can perhaps be probed by ESR and ENDOR techniques. Finally, we suggest that a perusal of literature on (semiconductor) cluster calculations carried out 30 years ago would be useful.

  17. Physics of semiconductor devices

    CERN Document Server

    Rudan, Massimo

    2015-01-01

    This book describes the basic physics of semiconductors, including the hierarchy of transport models, and connects the theory with the functioning of actual semiconductor devices.  Details are worked out carefully and derived from the basic physics, while keeping the internal coherence of the concepts and explaining various levels of approximation. Examples are based on silicon due to its industrial importance. Several chapters are included that provide the reader with the quantum-mechanical concepts necessary for understanding the transport properties of crystals. The behavior of crystals incorporating a position-dependent impurity distribution is described, and the different hierarchical transport models for semiconductor devices are derived (from the Boltzmann transport equation to the hydrodynamic and drift-diffusion models). The transport models are then applied to a detailed description of the main semiconductor-device architectures (bipolar, MOS). The final chapters are devoted to the description of s...

  18. Biggest semiconductor installed

    CERN Multimedia

    2008-01-01

    Scientists and technicians at the European Laboratory for Particle Physics, commonly known by its French acronym CERN (Centre Europen pour la Recherche Nuclaire), have completed the installation of the largest semiconductor silicon detector.

  19. Semiconductor type dependent role of metal nanoparticle in metal and semiconductor nanostructured junction.

    Science.gov (United States)

    Lee, Seung-Hoon; Jang, Jae-Won

    Among hybrid nanostructures, semiconductor with metal nanomaterial has been more exploited because metal and semiconductor have different properties that, in combination, result in unique electrical and optical properties. Localized surface plasmon resonance (LSPR), which is one of novel properties of metal nanoparticles (NPs), has been used as a good strategy for increasing an opto-electric performance in semiconductors. In this presentation, improvement of the opto-electronic properties of non-single crystallized nanowire (NW) devices with space charges generated by LSPR is demonstrated. The photocurrent and spectral response of single polypyrrole (PPy) NW devices are increased by electrostatically attached Ag NPs. In particular, it is also proved the space charge generation by LSPR of Ag NPs by means of characterizing current-voltage (J-V) dependence and finite differential time domain (FDTD) simulation on the NW devices. Moreover, semiconductor type dependent role of metal NP in metal NPs decorated semiconductor NW is demonstrated by using light irradiated Kevin probe force microscopy. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2015R1A1A1A05027681 and NRF-2016K1A3A1A32913212).

  20. Electrowetting on a semiconductor

    OpenAIRE

    Arscott, Steve; Gaudet, Matthieu

    2012-01-01

    We report electrowetting on a semiconductor using of a mercury droplet resting on a silicon surface. The effect is demonstrated using commercial n-type and p-type single-crystal (100) silicon wafers of different doping levels. The electrowetting is reversible - the voltage-dependent wetting contact angle variation of the mercury droplet is observed to depend on both the underlying semiconductor doping density and type. The electrowetting behaviour is explained by the voltage-dependent modulat...

  1. Radiation effects in semiconductors

    CERN Document Server

    2011-01-01

    There is a need to understand and combat potential radiation damage problems in semiconductor devices and circuits. Written by international experts, this book explains the effects of radiation on semiconductor devices, radiation detectors, and electronic devices and components. These contributors explore emerging applications, detector technologies, circuit design techniques, new materials, and innovative system approaches. The text focuses on how the technology is being used rather than the mathematical foundations behind it. It covers CMOS radiation-tolerant circuit implementations, CMOS pr

  2. A new FET-bipolar combinational power semiconductor switch

    Science.gov (United States)

    Chen, D. Y.; Chandrasekaran, S.; Chin, S. A.

    1984-01-01

    A novel FET-BJT combinational transistor configuration is proposed and demonstrated using discrete devices. This new transistor features fast switching, very simple drive requirement, elimination of reverse bias second breakdown, and good utilization of semiconductor chip area. Initial results indicate that power hybrid construction of the device is essential to enhance the current rating of the device.

  3. Semiconductor quantum dot scintillation under gamma-ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Letant, S E; Wang, T

    2006-08-23

    We recently demonstrated the ability of semiconductor quantum dots to convert alpha radiation into visible photons. In this letter, we report on the scintillation of quantum dots under gamma-ray irradiation, and compare the energy resolution of the 59 keV line of Americium 241 obtained with our quantum dot-glass nanocomposite material to that of a standard sodium iodide scintillator. A factor 2 improvement is demonstrated experimentally and interpreted theoretically using a combination of energy-loss and photon transport models. These results demonstrate the potential of quantum dots for room-temperature gamma-ray detection, which has applications in medical imaging, environmental monitoring, as well as security and defense. Present technology in gamma radiation detection suffers from flexibility and scalability issues. For example, bulk Germanium provides fine energy resolution (0.2% energy resolution at 1.33 MeV) but requires operation at liquid nitrogen temperature. On the other hand, Cadmium-Zinc-Telluride is a good room temperature detector ( 1% at 662 keV) but the size of the crystals that can be grown is limited to a few centimeters in each direction. Finally, the most commonly used scintillator, Sodium Iodide (NaI), can be grown as large crystals but suffers from a lack of energy resolution (7% energy resolution at 662 keV). Recent advancements in nanotechnology6-10 have provided the possibility of controlling materials synthesis at the molecular level. Both morphology and chemical composition can now be manipulated, leading to radically new material properties due to a combination of quantum confinement and surface to volume ratio effects. One of the main consequences of reducing the size of semiconductors down to nanometer dimensions is to increase the energy band gap, leading to visible luminescence, which suggests that these materials could be used as scintillators. The visible band gap of quantum dots would also ensure both efficient photon counting

  4. Synchrotron radiation studies of inorganic-organic semiconductor interfaces

    CERN Document Server

    Evans, D A; Vearey-Roberts, A R; Bushell, A; Cabailh, G; O'Brien, S; Wells, J W; McGovern, I T; Dhanak, V R; Kampen, T U; Zahn, D R T; Batchelor, D

    2003-01-01

    Organic semiconductors (polymers and small molecules) are widely used in electronic and optoelectronic technologies. Many devices are based on multilayer structures where interfaces play a central role in device performance and where inorganic semiconductor models are inadequate. Synchrotron radiation techniques such as photoelectron spectroscopy (PES), near-edge X-ray absorption fine structure (NEXAFS) and X-ray standing wave spectroscopy (XSW) provide a powerful means of probing the structural, electronic and chemical properties of these interfaces. The surface-specificity of these techniques allows key properties to be monitored as the heterostructure is fabricated. This methodology has been directed at the growth of hybrid organic-inorganic semiconductor interfaces involving copper phthalocyanine as the model organic material and InSb and GaAs as the model inorganic semiconductor substrates. Core level PES has revealed that these interfaces are abrupt and chemically inert due to the weak bonding between t...

  5. Novel room temperature ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Amita [KTH Royal Inst. of Technology, Stockholm (Sweden)

    2004-06-01

    distribution of Mn substituting for Zn a 2+ state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2+ state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS, revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.

  6. Hydrogen in semiconductors II

    CERN Document Server

    Nickel, Norbert H; Weber, Eicke R; Nickel, Norbert H

    1999-01-01

    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise that this tradition ...

  7. Basic Semiconductor Physics

    CERN Document Server

    Hamaguchi, Chihiro

    2010-01-01

    This book presents a detailed description of the basic semiconductor physics. The reader is assumed to have a basic command of mathematics and some elementary knowledge of solid state physics. The text covers a wide range of important phenomena in semiconductors, from the simple to the advanced. The reader can understand three different methods of energy band calculations, empirical pseudo-potential, k.p perturbation and tight-binding methods. The effective mass approximation and electron motion in a periodic potential, Boltzmann transport equation and deformation potentials used for full band Monte Carlo simulation are discussed. Experiments and theoretical analysis of cyclotron resonance are discussed in detail because the results are essential to the understanding of semiconductor physics. Optical and transport properties, magneto-transport, two dimensional electron gas transport (HEMT and MOSFET), and quantum transport are reviewed, explaining optical transition, electron phonon interactions, electron mob...

  8. Fundamentals of semiconductor lasers

    CERN Document Server

    Numai, Takahiro

    2015-01-01

    This book explains physics under the operating principles of semiconductor lasers in detail based on the experience of the author, dealing with the first manufacturing of phase-shifted DFB-LDs and recent research on transverse modes.   The book also bridges a wide gap between journal papers and textbooks, requiring only an undergraduate-level knowledge of electromagnetism and quantum mechanics, and helps readers to understand journal papers where definitions of some technical terms vary, depending on the paper. Two definitions of the photon density in the rate equations and two definitions of the phase-shift in the phase-shifted DFB-LD are explained, and differences in the calculated results are indicated, depending on the definitions.    Readers can understand the physics of semiconductor lasers and analytical tools for Fabry-Perot LDs, DFB-LDs, and VCSELs and will be stimulated to develop semiconductor lasers themselves.

  9. Compound semiconductor device physics

    CERN Document Server

    Tiwari, Sandip

    2013-01-01

    This book provides one of the most rigorous treatments of compound semiconductor device physics yet published. A complete understanding of modern devices requires a working knowledge of low-dimensional physics, the use of statistical methods, and the use of one-, two-, and three-dimensional analytical and numerical analysis techniques. With its systematic and detailed**discussion of these topics, this book is ideal for both the researcher and the student. Although the emphasis of this text is on compound semiconductor devices, many of the principles discussed will also be useful to those inter

  10. 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

  11. Introductory semiconductor device physics

    CERN Document Server

    Parker, Greg

    2004-01-01

    ATOMS AND BONDINGThe Periodic TableIonic BondingCovalent BondingMetallic bondingvan der Waals BondingStart a DatabaseENERGY BANDS AND EFFECTIVE MASSSemiconductors, Insulators and MetalsSemiconductorsInsulatorsMetalsThe Concept of Effective MassCARRIER CONCENTRATIONS IN SEMICONDUCTORSDonors and AcceptorsFermi-LevelCarrier Concentration EquationsDonors and Acceptors Both PresentCONDUCTION IN SEMICONDUCTORSCarrier DriftCarrier MobilitySaturated Drift VelocityMobility Variation with TemperatureA Derivation of Ohm's LawDrift Current EquationsSemiconductor Band Diagrams with an Electric Field Presen

  12. Ternary chalcopyrite semiconductors

    CERN Document Server

    Shay, J L; Pamplin, B R

    2013-01-01

    Ternary Chalcopyrite Semiconductors: Growth, Electronic Properties, and Applications covers the developments of work in the I-III-VI2 and II-IV-V2 ternary chalcopyrite compounds. This book is composed of eight chapters that focus on the crystal growth, characterization, and applications of these compounds to optical communications systems. After briefly dealing with the status of ternary chalcopyrite compounds, this book goes on describing the crystal growth of II-IV-V2 and I-III-VI2 single crystals. Chapters 3 and 4 examine the energy band structure of these semiconductor compounds, illustrat

  13. Optical processes in semiconductors

    CERN Document Server

    Pankove, Jacques I

    1975-01-01

    Based on a series of lectures at Berkeley, 1968-1969, this is the first book to deal comprehensively with all of the phenomena involving light in semiconductors. The author has combined, for the graduate student and researcher, a great variety of source material, journal research, and many years of experimental research, adding new insights published for the first time in this book.Coverage includes energy states in semiconductors and their perturbation by external parameters, absorption, relationships between optical constants, spectroscopy, radiative transitions, nonradiative recombination

  14. Growth of photovoltaic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yablonovitch, E. (Bell Communications Research, Red Bank, NJ (United States)); Stringfellow, G.B. (Univ. of Utah, Salt Lake City (United States)); Greene, J.E. (Univ. of Illinois, Urbana (United States))

    1993-01-01

    We assess the opportunities for improving the quality and lowering the cost of thin crystalline semiconductor films for photovoltaics. We find that novel growth and processing methods can lower the cost of crystalline semiconductor films to satisfy the economic conditions for a major expansion of the photovoltaic industry. The research requirements are in the areas of novel precursors for vapor phase growth, atomic layer epitaxy for unprecedented control, and the requirement for novel in situ and ex situ probes to ensure that the new growth methods are producing the utmost in photovoltaic material quality. 42 refs.

  15. Advances in semiconductor lasers

    CERN Document Server

    Coleman, James J; Jagadish, Chennupati

    2012-01-01

    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scien

  16. Metal semiconductor contacts and devices

    CERN Document Server

    Cohen, Simon S; Einspruch, Norman G

    1986-01-01

    VLSI Electronics Microstructure Science, Volume 13: Metal-Semiconductor Contacts and Devices presents the physics, technology, and applications of metal-semiconductor barriers in digital integrated circuits. The emphasis is placed on the interplay among the theory, processing, and characterization techniques in the development of practical metal-semiconductor contacts and devices.This volume contains chapters that are devoted to the discussion of the physics of metal-semiconductor interfaces and its basic phenomena; fabrication procedures; and interface characterization techniques, particularl

  17. Handbook of luminescent semiconductor materials

    CERN Document Server

    Bergman, Leah

    2011-01-01

    Photoluminescence spectroscopy is an important approach for examining the optical interactions in semiconductors and optical devices with the goal of gaining insight into material properties. With contributions from researchers at the forefront of this field, Handbook of Luminescent Semiconductor Materials explores the use of this technique to study semiconductor materials in a variety of applications, including solid-state lighting, solar energy conversion, optical devices, and biological imaging. After introducing basic semiconductor theory and photoluminescence principles, the book focuses

  18. Photon-Counting Arrays for Time-Resolved Imaging

    Directory of Open Access Journals (Sweden)

    I. Michel Antolovic

    2016-06-01

    Full Text Available The paper presents a camera comprising 512 × 128 pixels capable of single-photon detection and gating with a maximum frame rate of 156 kfps. The photon capture is performed through a gated single-photon avalanche diode that generates a digital pulse upon photon detection and through a digital one-bit counter. Gray levels are obtained through multiple counting and accumulation, while time-resolved imaging is achieved through a 4-ns gating window controlled with subnanosecond accuracy by a field-programmable gate array. The sensor, which is equipped with microlenses to enhance its effective fill factor, was electro-optically characterized in terms of sensitivity and uniformity. Several examples of capture of fast events are shown to demonstrate the suitability of the approach.

  19. Noise reduction in photon counting by exploiting spatial correlations

    Czech Academy of Sciences Publication Activity Database

    Peřina Jr., J.; Michálek, Václav; Haderka, Ondřej

    2017-01-01

    Roč. 8, č. 4 (2017), s. 1-12, č. článku 044018. ISSN 2331-7019 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : parametric down-conversion * quantum imaging applications * coherence properties Subject RIV: BH - Optics, Masers, Lasers Impact factor: 4.808, year: 2016

  20. Adaptive depth imaging method based on photon counting LIDAR

    Science.gov (United States)

    He, Weiji; Feng, Zhenchao; Lin, Jie; Shen, Shanshan; Chen, Qian; Gu, Guohua; Zhou, Beibei

    2017-02-01

    For an unknown characteristic target scene, the laser radar system that uses single-photon detector cannot directly estimate the dwell time of every pixel. Therefore, as the difference of target reflectivity, depth estimation appears inadequate sampling or redundant sampling in the conventional imaging method of maximum likelihood estimation (MLE-CIM). In this work, an adaptive depth imaging method (ADIM) is presented. ADIM is capable to obtain the depth estimation of target and adaptively decide the dwell time of each pixel. The experimental results reveal that ADIM can accurately obtain the 3D depth image of target even at the condition of low signal-to-noise ratio.

  1. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias

    2013-01-01

    In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz nonlinear......In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz...... is determined by (but not equal to) the electron momentum relaxation rate. Single cycle pulses of light, irrespective of the frequency range to which they belong, inherently have an ultrabroadband spectrum covering many octaves of frequencies. Unlike the single-cycle pulses in optical domain, the THz pulses can...... be easily sampled with sub-cycle resolution using conventional femtosecond lasers. This makes the THz pulses accessible model tools for direct observation of general nonlinear optical phenomena occurring in the single-cycle regime....

  2. Physics of semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Prew, B.A.

    1975-09-01

    The properties of semiconductors which make them important in the electronic devices industry, and how these properties are controlled by doping, are described. The physics and applications of p-n and other junction devices, and of bulk effect devices are discussed. Avalanche devices, optical devices, solar cells, Schottky barriers, MOS devices, heterojunctions, photoconductors, and transferred electron devices are considered.

  3. Defects in semiconductor nanostructures

    Indian Academy of Sciences (India)

    11] A detailed review article of defects in semiconductor nanostructures is currently under preparation. [12] V Ranjan and Vijay A Singh, J. Appl. Phys. 89, 6415 (2001). [13] V Ranjan, R K Pandey, Manoj K Harbola and Vijay A Singh, Phys. Rev.

  4. Magnetic field effects on Hybrid PhotoDiode single electron response

    CERN Document Server

    Damiani, C; Salvo, R D; Vitale, G; Domenico, G D; Zavattini, G; Benetti, P; Grassi, D; Marchesotti, M; Rossella, M

    2000-01-01

    Hybrid PhotoDiodes (HPDs) are very simple photo detectors which cover the applicability field of Photo Multipliers but show some better features. In particular HPDs show a very good photon counting capability, due to their peculiar one-stage gain process. It was found that HPD's photoelectron spectrum has a low-energy continuum which could be attributed to a backscattering process from the diode surface. In order to clearly distinguish the exact role of backscattering, the single photoelectron response (SER) of a 61 pixel proximity focused HPD was measured in standard conditions and in a 5 kG axial magnetic field. The results clearly indicate that the backscattering process gives the greatest contribution to the low-energy continuum spectrum. Monte Carlo simulations, using the EGS4 code, supported the analysis and allowed some interpretation of the effect, which greatly depends on diode surface characteristics, such as contact layer thickness.

  5. Large blue shift and strong optical anisotropy in ZnSe-based organic/inorganic hybrid nanostructures

    Science.gov (United States)

    Fu, Huaxiang

    2002-03-01

    A new class of ZnSe-based organic/inorganic hybrid materials with semiconductor nanolayers were recently synthesized. (H.R. Heulings, X. Huang, and J. Li, Nanoletters 1 (2001) 521.) Here we calculate the electronic structure and optical spectrum of hybrid material ZnSe(en) using local density-functional theory. Compared to the parental semiconductor, a surprising large blue shift of ~ 1.5eV is found in hybrid ZnSe(en), consistent with experimental observations. Our calculation results show that the dielectric function of the hybrid material is very different from that of bulk semiconductor. Interestingly, the near-edge absorption in hybrid ZnSe(en) almost exclusively comes from the semiconductor component, even when the semiconductor layer is down to a single atomic monolayer. Furthermore, the band-edge absorption in hybrid ZnSe(en) is revealed to be strongly polarized.

  6. Basic semiconductor physics

    CERN Document Server

    Hamaguchi, Chihiro

    2017-01-01

    This book presents a detailed description of basic semiconductor physics. The text covers a wide range of important phenomena in semiconductors, from the simple to the advanced. Four different methods of energy band calculations in the full band region are explained: local empirical pseudopotential, non-local pseudopotential, KP perturbation and tight-binding methods. The effective mass approximation and electron motion in a periodic potential, Boltzmann transport equation and deformation potentials used for analysis of transport properties are discussed. Further, the book examines experiments and theoretical analyses of cyclotron resonance in detail. Optical and transport properties, magneto-transport, two-dimensional electron gas transport (HEMT and MOSFET) and quantum transport are reviewed, while optical transition, electron-phonon interaction and electron mobility are also addressed. Energy and electronic structure of a quantum dot (artificial atom) are explained with the help of Slater determinants. The...

  7. Compound semiconductor device modelling

    CERN Document Server

    Miles, Robert

    1993-01-01

    Compound semiconductor devices form the foundation of solid-state microwave and optoelectronic technologies used in many modern communication systems. In common with their low frequency counterparts, these devices are often represented using equivalent circuit models, but it is often necessary to resort to physical models in order to gain insight into the detailed operation of compound semiconductor devices. Many of the earliest physical models were indeed developed to understand the 'unusual' phenomena which occur at high frequencies. Such was the case with the Gunn and IMPATI diodes, which led to an increased interest in using numerical simulation methods. Contemporary devices often have feature sizes so small that they no longer operate within the familiar traditional framework, and hot electron or even quantum­ mechanical models are required. The need for accurate and efficient models suitable for computer aided design has increased with the demand for a wider range of integrated devices for operation at...

  8. Single frequency semiconductor lasers

    CERN Document Server

    Fang, Zujie; Chen, Gaoting; Qu, Ronghui

    2017-01-01

    This book systematically introduces the single frequency semiconductor laser, which is widely used in many vital advanced technologies, such as the laser cooling of atoms and atomic clock, high-precision measurements and spectroscopy, coherent optical communications, and advanced optical sensors. It presents both the fundamentals and characteristics of semiconductor lasers, including basic F-P structure and monolithic integrated structures; interprets laser noises and their measurements; and explains mechanisms and technologies relating to the main aspects of single frequency lasers, including external cavity lasers, frequency stabilization technologies, frequency sweeping, optical phase locked loops, and so on. It paints a clear, physical picture of related technologies and reviews new developments in the field as well. It will be a useful reference to graduate students, researchers, and engineers in the field.

  9. Semiconductor physics an introduction

    CERN Document Server

    Seeger, Karlheinz

    1999-01-01

    Semiconductor Physics - An Introduction - is suitable for the senior undergraduate or new graduate student majoring in electrical engineering or physics. It will also be useful to solid-state scientists and device engineers involved in semiconductor design and technology. The text provides a lucid account of charge transport, energy transport and optical processes, and a detailed description of many devices. It includes sections on superlattices and quantum well structures, the effects of deep-level impurities on transport, the quantum Hall effect and the calculation of the influence of a magnetic field on the carrier distribution function. This 6th edition has been revised and corrected, and new sections have been added to different chapters.

  10. Wafer Fusion for Integration of Semiconductor Materials and Devices

    Energy Technology Data Exchange (ETDEWEB)

    Choquette, K.D.; Geib, K.M.; Hou, H.Q.; Allerman, A.A.; Kravitz, S.; Follstaedt, D.M.; Hindi, J.J.

    1999-05-01

    We have developed a wafer fusion technology to achieve integration of semiconductor materials and heterostructures with widely disparate lattice parameters, electronic properties, and/or optical properties for novel devices not now possible on any one substrate. Using our simple fusion process which uses low temperature (400-600 C) anneals in inert N{sub 2} gas, we have extended the scope of this technology to examine hybrid integration of dissimilar device technologies. As a specific example, we demonstrate wafer bonding vertical cavity surface emitting lasers (VCSELs) to transparent AlGaAs and GaP substrates to fabricate bottom-emitting short wavelength VCSELs. As a baseline fabrication technology applicable to many semiconductor systems, wafer fusion will revolutionize the way we think about possible semiconductor devices, and enable novel device configurations not possible by epitaxial growth.

  11. Infrared Semiconductor Metamaterials

    Science.gov (United States)

    2016-09-01

    AFRL-AFOSR-VA-TR-2016-0310 Infrared Semiconductor Metamaterials Jon Schuller UNIVERSITY OF CALIFORNIA SANTA BARBARA 3227 CHEADLE HL SANTA BARBARA, CA...S) AND ADDRESS(ES) University of California , Santa Barbara Office of Research, 3227 Cheadle Hall Santa Barbara, CA 93106-2050 8. PERFORMING...Using Heterojunction Resonators. Advanced Optical Materials, available online (2016). New discoveries, inventions, or patent disclosures: Do you have

  12. Nonradiative recombination in semiconductors

    CERN Document Server

    Abakumov, VN; Yassievich, IN

    1991-01-01

    In recent years, great progress has been made in the understandingof recombination processes controlling the number of excessfree carriers in semiconductors under nonequilibrium conditions. As a result, it is now possible to give a comprehensivetheoretical description of these processes. The authors haveselected a number of experimental results which elucidate theunderlying physical problems and enable a test of theoreticalmodels. The following topics are dealt with: phenomenological theory ofrecombination, theoretical models of shallow and deep localizedstates, cascade model of carrier captu

  13. Hole crystallization in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bonitz, M [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet Kiel, 24098 Kiel (Germany); Filinov, V S [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet Kiel, 24098 Kiel (Germany); Fortov, V E [Institute for High Energy Density, Russian Academy of Sciences, Izhorskay 13/19, Moscow 127412 (Russian Federation); Levashov, P R [Institute for High Energy Density, Russian Academy of Sciences, Izhorskay 13/19, Moscow 127412 (Russian Federation); Fehske, H [Institut fuer Physik, Universitaet Greifswald, l7487 Greifswald (Germany)

    2006-04-28

    When electrons in a solid are excited to a higher energy band they leave behind a vacancy (hole) in the original band which behaves like a positively charged particle. Here we predict that holes can spontaneously order into a regular lattice in semiconductors with sufficiently flat valence bands. The critical hole to electron effective mass ratio required for this phase transition is found to be of the order of 80.

  14. Hole crystallization in semiconductors

    OpenAIRE

    Bonitz, M.; Filinov, V. S.; Fortov, V. E.; Levashov, P. R.; Fehske, H.

    2005-01-01

    When electrons in a solid are excited to a higher energy band they leave behind a vacancy (hole) in the original band which behaves like a positively charged particle. Here we predict that holes can spontaneously order into a regular lattice in semiconductors with sufficiently flat valence bands. The critical hole to electron effective mass ratio required for this phase transition is found to be of the order of 80.

  15. Survey of semiconductor physics

    CERN Document Server

    Böer, Karl W

    1992-01-01

    Any book that covers a large variety of subjects and is written by one author lacks by necessity the depth provided by an expert in his or her own field of specialization. This book is no exception. It has been written with the encouragement of my students and colleagues, who felt that an extensive card file I had accumulated over the years of teaching solid state and semiconductor physics would be helpful to more than just a few of us. This file, updated from time to time, contained lecture notes and other entries that were useful in my research and permitted me to give to my students a broader spectrum of information than is available in typical textbooks. When assembling this material into a book, I divided the top­ ics into material dealing with the homogeneous semiconductor, the subject of the previously published Volume 1, and the inhomoge­ neous semiconductor, the subject of this Volume 2. In order to keep the book to a manageable size, sections of tutorial character which can be used as text for a g...

  16. Hybrid solar cells based on MEH-PPV and thin film semiconductor oxides (TiO2, Nb2O5, ZnO, CeO2 and CeO2–TiO2): Performance improvement during long-time irradiation

    DEFF Research Database (Denmark)

    Lira-Cantu, M.; Krebs, Frederik C

    2006-01-01

    prepared as bi-layers of thin film semiconducting oxides (TiO2, Nb2O5, ZnO, CeO2-TiO2 and CeO2) and the polymer MEH-PPV, with a final device configuration of ITO/ Oxide(thin) (film)/MEH-PPV/Ag. The oxides were prepared as thin transparent films from sol-gel solutions. The photovoltaic cells were studied...... density was observed after 15h; for CeO2, the maximum performance was observed after 30h. The only exception was observed with devices applying ZnO in which the current density decreased drastically and degraded the polymer in just a couple of hours. (c) 2006 Elsevier B.V. All rights reserved.......Performance improvement of hybrid solar cells (HSC) applying five different thin film semiconductor oxides has been observed during long-time irradiation in ambient atmosphere. This behavior shows a direct relation between HSC and oxygen content from the environment. Photovoltaic devices were...

  17. Electrical properties of GaAs metal–oxide–semiconductor structure comprising Al2O3 gate oxide and AlN passivation layer fabricated in situ using a metal–organic vapor deposition/atomic layer deposition hybrid system

    Directory of Open Access Journals (Sweden)

    Takeshi Aoki

    2015-08-01

    Full Text Available This paper presents a compressive study on the fabrication and optimization of GaAs metal–oxide–semiconductor (MOS structures comprising a Al2O3 gate oxide, deposited via atomic layer deposition (ALD, with an AlN interfacial passivation layer prepared in situ via metal–organic chemical vapor deposition (MOCVD. The established protocol afforded self-limiting growth of Al2O3 in the atmospheric MOCVD reactor. Consequently, this enabled successive growth of MOCVD-formed AlN and ALD-formed Al2O3 layers on the GaAs substrate. The effects of AlN thickness, post-deposition anneal (PDA conditions, and crystal orientation of the GaAs substrate on the electrical properties of the resulting MOS capacitors were investigated. Thin AlN passivation layers afforded incorporation of optimum amounts of nitrogen, leading to good capacitance–voltage (C–V characteristics with reduced frequency dispersion. In contrast, excessively thick AlN passivation layers degraded the interface, thereby increasing the interfacial density of states (Dit near the midgap and reducing the conduction band offset. To further improve the interface with the thin AlN passivation layers, the PDA conditions were optimized. Using wet nitrogen at 600 °C was effective to reduce Dit to below 2 × 1012 cm−2 eV−1. Using a (111A substrate was also effective in reducing the frequency dispersion of accumulation capacitance, thus suggesting the suppression of traps in GaAs located near the dielectric/GaAs interface. The current findings suggest that using an atmosphere ALD process with in situ AlN passivation using the current MOCVD system could be an efficient solution to improving GaAs MOS interfaces.

  18. Electrodes for Semiconductor Gas Sensors

    Science.gov (United States)

    Lee, Sung Pil

    2017-01-01

    The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode–semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode–semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect. PMID:28346349

  19. Method of passivating semiconductor surfaces

    Science.gov (United States)

    Wanlass, M.W.

    1990-06-19

    A method is described for passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

  20. Transparent Oxide Semiconductors for Emerging Electronics

    KAUST Repository

    Caraveo-Frescas, Jesus Alfonso

    2013-11-01

    demonstrated by the fabrication of hybrid ferroelectric field effect transistors composed of organic ferroelectric layer polyvinylidene fluoride trifluoroethylene and inorganic p-type semiconductor tin monoxide. Both rigid and flexible devices are demonstrated, showing the advantages of low temperature oxides over polymer semiconductors by achieving much better performance, such as order of magnitude higher hole mobility.

  1. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  2. Hydrogen in semiconductors

    CERN Document Server

    Pankove, Jacques I

    1991-01-01

    Hydrogen plays an important role in silicon technology, having a profound effect on a wide range of properties. Thus, the study of hydrogen in semiconductors has received much attention from an interdisciplinary assortment of researchers. This sixteen-chapter volume provides a comprehensive review of the field, including a discussion of hydrogenation methods, the use of hydrogen to passivate defects, the use of hydrogen to neutralize deep levels, shallow acceptors and shallow donors in silicon, vibrational spectroscopy, and hydrogen-induced defects in silicon. In addition to this detailed cove

  3. Physics of Organic Semiconductors

    CERN Document Server

    Brütting, Wolfgang

    2005-01-01

    Filling the gap in the literature currently available, this book presents an overview of our knowledge of the physics behind organic semiconductor devices. Contributions from 18 international research groups cover various aspects of this field, ranging from the growth of organic layers and crystals, their electronic properties at interfaces, their photophysics and electrical transport properties to the application of these materials in such different devices as organic field-effect transistors, photovoltaic cells and organic light-emitting diodes. From the contents:. * Excitation Dynamics in O

  4. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M

    2013-01-01

    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  5. Basic properties of semiconductors

    CERN Document Server

    Landsberg, PT

    2013-01-01

    Since Volume 1 was published in 1982, the centres of interest in the basic physics of semiconductors have shifted. Volume 1 was called Band Theory and Transport Properties in the first edition, but the subject has broadened to such an extent that Basic Properties is now a more suitable title. Seven chapters have been rewritten by the original authors. However, twelve chapters are essentially new, with the bulk of this work being devoted to important current topics which give this volume an almost encyclopaedic form. The first three chapters discuss various aspects of modern band theory and the

  6. Doped semiconductor nanocrystal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Ł.; Mélin, T., E-mail: thierry.melin@isen.iemn.univ-lille1.fr [Institut d’Electronique, de Microélectronique et de Nanotechnologie, CNRS-UMR8520, Avenue Poincaré, F-59652 Villeneuve d’Ascq (France); Nguyen-Tran, T.; Roca i Cabarrocas, P. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS-UMR7647, Ecole Polytechnique, F-91128 Palaiseau (France)

    2013-11-28

    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (N{sub D}≈10{sup 20}−10{sup 21}cm{sup −3}) silicon nanocrystals (NCs) in the 2–50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N{sub D}{sup −1/3}, and depleted charge linearly increasing with the NC diameter and varying as N{sub D}{sup 1/3}. We thus establish a “nanocrystal counterpart” of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  7. Squeezed light in semiconductors

    CERN Document Server

    Ward, M B

    2001-01-01

    Experimental evidence is presented for the generation of photon-number squeezed states of light as a result of multi-photon absorption. Photon-number squeezing as a result of non-linear absorption has long been predicted and results have been obtained utilising two very different material systems: (i) an AIGaAs waveguide in which high optical intensities can be maintained over a relatively long interaction length of 2 mm; (ii) the organic polymer p-toluene sulphonate polydiacetylene that is essentially a one-dimensional semiconductor possessing a highly nonlinear optical susceptibility. The resulting nonlinear absorption is shown to leave the transmitted light in a state that is clearly nonclassical, exhibiting photon-number fluctuations below the shot-noise limit. Tuning the laser wavelength across the half-bandgap energy has enabled a comparison between two- and three-photon processes in the semiconductor waveguide. The correlations created between different spectral components of a pulsed beam of light as ...

  8. II-VI semiconductor compounds

    CERN Document Server

    1993-01-01

    For condensed matter physicists and electronic engineers, this volume deals with aspects of II-VI semiconductor compounds. Areas covered include devices and applications of II-VI compounds; Co-based II-IV semi-magnetic semiconductors; and electronic structure of strained II-VI superlattices.

  9. Variable temperature semiconductor film deposition

    Science.gov (United States)

    Li, X.; Sheldon, P.

    1998-01-27

    A method of depositing a semiconductor material on a substrate is disclosed. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  10. Process for producing chalcogenide semiconductors

    Science.gov (United States)

    Noufi, R.; Chen, Y.W.

    1985-04-30

    A process for producing chalcogenide semiconductor material is disclosed. The process includes forming a base metal layer and then contacting this layer with a solution having a low pH and containing ions from at least one chalcogen to chalcogenize the layer and form the chalcogenide semiconductor material.

  11. Semiconductor materials and their properties

    NARCIS (Netherlands)

    Reinders, Angelina H.M.E.; Verlinden, Pierre; van Sark, Wilfried; Freundlich, Alexandre; Reinders, Angele; Verlinden, Pierre; van Sark, Wilfried; Freundlich, Alexandre

    2017-01-01

    Semiconductor materials are the basic materials which are used in photovoltaic (PV) devices. This chapter introduces solid-state physics and semiconductor properties that are relevant to photovoltaics without spending too much time on unnecessary information. Usually atoms in the group of

  12. Semiconductor photocatalysis principles and applications

    CERN Document Server

    Kisch, Horst

    2014-01-01

    Focusing on the basic principles of semiconductor photocatalysis, this book also gives a brief introduction to photochemistry, photoelectrochemistry, and homogeneous photocatalysis. In addition, the author - one of the leading authorities in the field - presents important environmental and practical aspects. A valuable, one-stop source for all chemists, material scientists, and physicists working in this area, as well as novice researchers entering semiconductor photocatalysis.

  13. Luminescence studies of semiconductor electrodes

    NARCIS (Netherlands)

    Kelly, J.J.; Kooij, Ernst S.; Meulenkamp, E.A.

    1999-01-01

    In this paper we review our recent results of in-situ luminescence studies of semiconductor electrodes. Three classes of materials are considered: single crystal compound semiconductors, porous silicon and semiconducting oxides doped with luminescent ions. We show how photoluminescence (PL) and

  14. Organic semiconductors in a spin

    CERN Document Server

    Samuel, I

    2002-01-01

    A little palladium can go a long way in polymer-based light-emitting diodes. Inorganic semiconductors such as silicon and gallium arsenide are essential for countless applications in everyday life, ranging from PCs to CD players. However, while they offer unrivalled computational speed, inorganic semiconductors are also rigid and brittle, which means that they are less suited to applications such as displays and flexible electronics. A completely different class of materials - organic semiconductors - are being developed for these applications. Organic semiconductors have many attractive features: they are easy to make, they can emit visible light, and there is tremendous scope for tailoring their properties to specific applications by changing their chemical structure. Research groups and companies around the world have developed a wide range of organic-semiconductor devices, including transistors, light-emitting diodes (LEDs), solar cells and lasers. (U.K.)

  15. Photocatalysis Using Semiconductor Nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Thurston, T.R.; Wilcoxon,J.P.

    1999-01-21

    We report on experiments using nanosize MoS{sub 2} to photo-oxidize organic pollutants in water using visible light as the energy source. We have demonstrated that we can vary the redox potentials and absorbance characteristics of these small semiconductors by adjusting their size, and our studies of the photooxidation of organic molecules have revealed that the rate of oxidation increases with increasing bandgap (i.e. more positive valence band and more negative conduction band potentials). Because these photocatalysis reactions can be performed with the nanoclusters fully dispersed and stable in solution, liquid chromatography can be used to determine both the intermediate reaction products and the state of the nanoclusters during the reaction. We have demonstrated that the MoS{sub 2} nanoclusters remain unchanged during the photooxidation process by this technique. We also report on studies of MoS{sub 2} nanoclusters deposited on TiO{sub 2} powder.

  16. Semiconductor radiation detector

    Science.gov (United States)

    Bell, Zane W.; Burger, Arnold

    2010-03-30

    A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

  17. Semiconductor optoelectronic infrared spectroscopy

    CERN Document Server

    Hollingworth, A R

    2001-01-01

    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 this technique has been shown that the inhomogeneous broadening of the photoluminescence spectrum is not purely affected by just size and composition. We suggest that other processes such as state occupancy, In roughing, and exciton binding energies may account for the extra energy. 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 futu...

  18. Semiconductor adiabatic qubits

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Malcolm S.; Witzel, Wayne; Jacobson, Noah Tobias; Ganti, Anand; Landahl, Andrew J.; Lilly, Michael; Nguyen, Khoi Thi; Bishop, Nathaniel; Carr, Stephen M.; Bussmann, Ezra; Nielsen, Erik; Levy, James Ewers; Blume-Kohout, Robin J.; Rahman, Rajib

    2016-12-27

    A quantum computing device that includes a plurality of semiconductor adiabatic qubits is described herein. The qubits are programmed with local biases and coupling terms between qubits that represent a problem of interest. The qubits are initialized by way of a tuneable parameter, a local tunnel coupling within each qubit, such that the qubits remain in a ground energy state, and that initial state is represented by the qubits being in a superposition of |0> and |1> states. The parameter is altered over time adiabatically or such that relaxation mechanisms maintain a large fraction of ground state occupation through decreasing the tunnel coupling barrier within each qubit with the appropriate schedule. The final state when tunnel coupling is effectively zero represents the solution state to the problem represented in the |0> and |1> basis, which can be accurately read at each qubit location.

  19. Semiconductor-superconductor optoelectronic devices

    Science.gov (United States)

    Bouscher, Shlomi; Panna, Dmitry; Hayat, Alex

    2017-10-01

    Devices combining superconductors with semiconductors offer a wide range of applications, particularly in the growing field of quantum information processing. This is due to their ability to take advantage of both the extensive knowledge gathered in the field of semiconductors and the unique quantum properties of superconductors. This results in novel device concepts, such as structures generating and detecting entangled photon pairs as well as novel optical gain and laser realizations. In this review, we discuss the fundamental concepts and the underlying physical phenomena of superconductor-semiconductor optoelectronics as well as practical device implementations.

  20. Semiconductor Nanocrystals for Biological Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Aihua; Gu, Weiwei; Larabell, Carolyn; Alivisatos, A. Paul

    2005-06-28

    Conventional organic fluorophores suffer from poor photo stability, narrow absorption spectra and broad emission feature. Semiconductor nanocrystals, on the other hand, are highly photo-stable with broad absorption spectra and narrow size-tunable emission spectra. Recent advances in the synthesis of these materials have resulted in bright, sensitive, extremely photo-stable and biocompatible semiconductor fluorophores. Commercial availability facilitates their application in a variety of unprecedented biological experiments, including multiplexed cellular imaging, long-term in vitro and in vivo labeling, deep tissue structure mapping and single particle investigation of dynamic cellular processes. Semiconductor nanocrystals are one of the first examples of nanotechnology enabling a new class of biomedical applications.

  1. Toward designing semiconductor-semiconductor heterojunctions for photocatalytic applications

    Science.gov (United States)

    Zhang, Liping; Jaroniec, Mietek

    2018-02-01

    Semiconductor photocatalysts show a great potential for environmental and energy-related applications, however one of the major disadvantages is their relatively low photocatalytic performance due to the recombination of electron-hole pairs. Therefore, intensive research is being conducted toward design of heterojunctions, which have been shown to be effective for improving the charge-transfer properties and efficiency of photocatalysts. According to the type of band alignment and direction of internal electric field, heterojunctions are categorized into five different types, each of which is associated with its own charge transfer characteristics. Since the design of heterojunctions requires the knowledge of band edge positions of component semiconductors, the commonly used techniques for the assessment of band edge positions are reviewed. Among them the electronegativity-based calculation method is applied for a large number of popular visible-light-active semiconductors, including some widely investigated bismuth-containing semiconductors. On basis of the calculated band edge positions and the type of component semiconductors reported, heterojunctions composed of the selected bismuth-containing semiconductors are proposed. Finally, the most popular synthetic techniques for the fabrication of heterojunctions are briefly discussed.

  2. Role of metal d states in II-VI semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wei, S.; Zunger, A.

    1988-05-15

    All-electron band-structure calculations and photoemission experiments on II-VI semiconductors both exhibit a metal d subband inside the main valence band. It has nevertheless been customary in pseudopotential and tight-binding approaches to neglect the metal d band by choosing Hamiltonian parameters which place this band inside the chemically inert atomic cores. Using all-electron self-consistent electronic-structure techniques (which treat the outermost d electrons on the same footing as other valence electrons) and comparing the results to those obtained by methods which remove the d band from the valence spectrum, we study their effects on valence properties. For II-VI semiconductors we find that p-d repulsion and hybridization (i) lower the band gaps, (ii) reduce the cohesive energy, (iii) increase the equilibrium lattice parameters, (iv) reduce the spin-orbit splitting, (v) alter the sign of the crystal-field splitting, (vi) increase the valence-band offset between common-anion II-VI semiconductors, and (vii) modify the charge distributions of various II-VI systems and their alloys. p-d repulsion is also shown to be responsible for the occurrence of deep Cu acceptor levels in II-VI semiconductors (compared with shallow acceptors of Zn in III-V), for the anomalously small band gaps in chalcopyrites, and for the negative exchange splitting in ferromagnetic MnTe.

  3. Atomic layer deposition for semiconductors

    CERN Document Server

    Hwang, Cheol Seong

    2014-01-01

    This edited volume discusses atomic layer deposition (ALD) for all modern semiconductor devices, moving from the basic chemistry of ALD and modeling of ALD processes to sections on ALD for memories, logic devices, and machines.

  4. Semiconductor radiation detectors. Device physics

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, G. [Max-Planck-Institutes for Physics and Extraterrestrial Physics, Muenchen (Germany). Semiconductor Lab.

    2007-07-01

    Starting from basic principles, the author, whose own contributions to these developments have been significant, describes the rapidly growing field of modern semiconductor detectors used for energy and position measurement radiation. This development was stimulated by requirements in elementary particle physics where it has led to important scientific discoveries. It has now spread to many other fields of science and technology. The book is written in a didactic way and includes an introduction to semiconductor physics. The working principles of semiconductor radiation detectors are explained in an intuitive way, followed by formal quantitative analysis. Broad coverage is also given to electronic signal readout and to the subject of radiation damage. The book is the first to comprehensively cover the semiconductor radiation detectors currently in use. It is useful as a teaching guide and as a reference work for research and applications. (orig.)

  5. Physics of semiconductor laser devices

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, G.H.B.

    1980-01-01

    Aspects of laser design and development are considered along with semiconductor materials for lasers, problems of device fabrication, crystal growth, the degradation of lasers, and the integration of semiconductor lasers with other optical components. A description is presented of light emission processes and laser action in semiconductors, taking into account electronic radiative transitions, the relation between emission and absorption processes, transition probabilities, the density of electron states in the highly doped semiconductor, carrier recombination and spontaneous emission, the gain/current relation, light-current characteristics, optical modes, and the evolution of mode spectrum and intensity with current. Attention is given to laser heterostructures and the properties of heterojunctions, optical waveguides, the performance of heterostructure lasers, stripe geometry lasers, and the dynamic response of lasers. Lasers with distributed feedback and Bragg reflectors are also discussed.

  6. Quantum optics with semiconductor nanostructures

    CERN Document Server

    Jahnke, Frank

    2012-01-01

    A guide to the theory, application and potential of semiconductor nanostructures in the exploration of quantum optics. It offers an overview of resonance fluorescence emission.$bAn understanding of the interaction between light and matter on a quantum level is of fundamental interest and has many applications in optical technologies. The quantum nature of the interaction has recently attracted great attention for applications of semiconductor nanostructures in quantum information processing. Quantum optics with semiconductor nanostructures is a key guide to the theory, experimental realisation, and future potential of semiconductor nanostructures in the exploration of quantum optics. Part one provides a comprehensive overview of single quantum dot systems, beginning with a look at resonance fluorescence emission. Quantum optics with single quantum dots in photonic crystal and micro cavities are explored in detail, before part two goes on to review nanolasers with quantum dot emitters. Light-matter interaction...

  7. Semiconductor nanocrystals or quantum dots

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 8. Various Quantum Mechanical Concepts for Confinements in Semiconductor Nanocrystals. Jayakrishna Khatei Karuna Kar Nanda. Classroom Volume 18 Issue 8 August 2013 pp 771-776 ...

  8. Semiconductor packaging materials interaction and reliability

    CERN Document Server

    Chen, Andrea

    2012-01-01

    In semiconductor manufacturing, understanding how various materials behave and interact is critical to making a reliable and robust semiconductor package. Semiconductor Packaging: Materials Interaction and Reliability provides a fundamental understanding of the underlying physical properties of the materials used in a semiconductor package. The book focuses on an important step in semiconductor manufacturing--package assembly and testing. It covers the basics of material properties and explains how to determine which behaviors are important to package performance. The authors also discuss how

  9. Fractal properties of nanostructured semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhanabaev, Z.Zh. [Al-Farabi Khazakh National University, Tole bi Street, 96, Almaty 050012 (Kazakhstan); Grevtseva, T.Yu. [Al-Farabi Khazakh National University, Tole bi Street, 96, Almaty 050012 (Kazakhstan)]. E-mail: kenwp@mail.ru

    2007-03-15

    A theory for the temperature and time dependence of current carrier concentration in semiconductors with different non-equilibrium nanocluster structure has been developed. It was shown that the scale-invariant fractal self-similar and self-affine laws can exist near by the transition point to the equilibrium state. Results of the theory have been compared to the experimental data from electrical properties of semiconductor films with nanoclusters.

  10. Dissipative chaos in semiconductor superlattices

    Directory of Open Access Journals (Sweden)

    F. Moghadam

    2008-03-01

    Full Text Available In this paper the motion of electron in a miniband of a semiconductor superlattice (SSL under the influence of external electric and magnetic fields is investigated. The electric field is applied in a direction perpendicular to the layers of the semiconductor superlattice, and the magnetic field is applied in different direction Numerical calculations show conditions led to the possibility of chaotic behaviors.

  11. Nonlinear Optical Interactions in Semiconductors.

    Science.gov (United States)

    1985-12-10

    Physique du Solide et Energie Solaire We had on-going interaction with Dr. Christian Verie on the growth of high quality narrow-gap semiconductor crystals...The band gap energy of the semiconductor decreases with increasing temperature. Consequently, the absorption of light in the energy region of the...gas and, more importantly, will modulate the electron energy at the difference frequency, wI - 02" Under ordinary circumstances such an energy (or

  12. Semiconductor Alloy Theory.

    Science.gov (United States)

    1985-09-27

    probability amplitude of finding the _ cation’ hybrid in the bonding state. etc.. ’Reference 12. a,, V 2 + V is the polarity, The last identity in Eq...of the common adjacent atom C. sp U A(1) is the probability amplitude of finding an electron in the hybridb orbital of the C atom in the bonding state...of an AC bond with a bond length Bdi whereas U (2) is the corresponding probability amplitude for the 1’ a ...- antibonding state of a BC bond of

  13. The ATLAS semiconductor tracker

    CERN Document Server

    Mikuz, Marko

    2003-01-01

    The ATLAS Semiconductor Tracker (SCT) is presented. About 16000 silicon micro-strip sensors with a total active surface of over 60 m **2 and with 6.3 million read-out channels are built into 4088 modules arranged into four barrel layers and nine disks covering each of the forward regions up to an eta of 2.5. Challenges are imposed by the hostile radiation environment with particle fluences up to 2 multiplied by 10**1**4 cm**-**2 1 MeV neutron NIEL equivalent and 100 kGy TID, the 25 ns LHC bunch crossing time and the need for a hermetic, lightweight tracker. The solution adopted is carefully designed strip detectors operated at -7 degree C, biased up to 500 V and read out by binary radhard fast BiCMOS electronics. A zero-CTE carbon fibre structure provides mechanical support. 30 kW of power are supplied on aluminiutn/Kapton tapes and cooled by C//3F//8 evaporative cooling. Data and commands are transferred by optical links. Prototypes of detector modules have been built, irradiated to the maximum expected flue...

  14. Photophysics of Organic-Inorganic Hybrid Lead Iodide Perovskite Single Crystals

    NARCIS (Netherlands)

    Fang, Honghua; Raissa, Raissa; Abdu-Aguye, Mustapha; Adjokatse, Sampson; Blake, Graeme R.; Even, Jacky; Loi, Maria Antonietta

    2015-01-01

    Hybrid organometal halide perovskites have been demonstrated to have outstanding performance as semiconductors for solar energy conversion. Further improvement of the efficiency and stability of these devices requires a deeper understanding of their intrinsic photophysical properties. Here, the

  15. A CMOS-Compatible Hybrid Plasmonic Slot Waveguide With Enhanced Field Confinement

    NARCIS (Netherlands)

    Xiao, Jing; Wei, Qi-Qin; Yang, Daoguo; Zhang, Ping; He, Ning; Zhang, G.Q.; Ren, Tian-Ling; Chen, XP

    2016-01-01

    The emerging field of nanophotonics requires plasmonic devices to be fully compatible with semiconductor fabrication techniques. However, very few feasible practical structures exist at present. Here, we propose a CMOS-compatible hybrid plasmonic slot waveguide (HPSW) with enhanced field

  16. EDITORIAL: Oxide semiconductors

    Science.gov (United States)

    Kawasaki, M.; Makino, T.

    2005-04-01

    Blue or ultraviolet semiconducting light-emitting diodes have the potential to revolutionize illumination systems in the near-future. Such industrial need has propelled the investigation of several wide-gap semiconducting materials in recent years. Commercial applications include blue lasers for DVD memory and laser printers, while military applications are also expected. Most of the material development has so far been focused on GaN (band gap 3.5 eV at 2 K), and ZnSe (2.9 eV) because these two representative direct transition semiconductors are known to be bright emitting sources. GaN and GaN-based alloys are emerging as the winners in this field because ZnSe is subject to defect formation under high current drive. On the other hand, another II-VI compound, ZnO, has also excited substantial interest in the optoelectronics-oriented research communities because it is the brightest emitter of all, owing to the fact that its excitons have a 60 meV binding energy. This is compared with 26 meV for GaN and 20 meV for ZnSe. The stable excitons could lead to laser action based on their recombination even at temperatures well above room temperature. ZnO has additional major properties that are more advantageous than other wide-gap materials: availability of large area substrates, higher energy radiation stability, environmentally-friendly ingredients, and amenability to wet chemical etching. However, ZnO is not new to the semiconductor field as exemplified by several studies made during the 1960s on structural, vibrational, optical and electrical properties (Mollwo E 1982 Landolt-Boernstein New Series vol 17 (Berlin: Springer) p 35). In terms of devices, the luminescence from light-emitting diode structures was demonstrated in which Cu2O was used as the p-type material (Drapak I T 1968 Semiconductors 2 624). The main obstacle to the development of ZnO has been the lack of reproducible p-type ZnO. The possibility of achieving epitaxial p-type layers with the aid of thermal

  17. Metalloporphyrin-modified semiconductors for solar fuel production.

    Science.gov (United States)

    Khusnutdinova, D; Beiler, A M; Wadsworth, B L; Jacob, S I; Moore, G F

    2017-01-01

    We report a direct one-step method to chemically graft metalloporphyrins to a visible-light-absorbing gallium phosphide semiconductor with the aim of constructing an integrated photocathode for light activating chemical transformations that include capturing, converting, and storing solar energy as fuels. Structural characterization of the hybrid assemblies is achieved using surface-sensitive spectroscopic methods, and functional performance for photoinduced hydrogen production is demonstrated via three-electrode electrochemical testing combined with photoproduct analysis using gas chromatography. Measurements of the total per geometric area porphyrin surface loadings using a cobalt-porphyrin based assembly indicate a turnover frequency ≥3.9 H2 molecules per site per second, representing the highest reported to date for a molecular-catalyst-modified semiconductor photoelectrode operating at the H+/H2 equilibrium potential under 1-sun illumination.

  18. Thin film transistors for flexible electronics: Contacts, dielectrics and semiconductors

    KAUST Repository

    Quevedo-López, Manuel Angel Quevedo

    2011-06-01

    The development of low temperature, thin film transistor processes that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, radiation detectors, etc. In this paper, we review the impact of gate dielectrics, contacts and semiconductor materials on thin film transistors for flexible electronics applications. We present our recent results to fully integrate hybrid complementary metal oxide semiconductors comprising inorganic and organic-based materials. In particular, we demonstrate novel gate dielectric stacks and semiconducting materials. The impact of source and drain contacts on device performance is also discussed. Copyright © 2011 American Scientific Publishers.

  19. Asymmetric Hybrid Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chumanov, George [Clemson Univ., SC (United States)

    2015-11-05

    Hybrid Nanoparticles (AHNs) are rationally-designed multifunctional nanostructures and novel building blocks for the next generation of advanced materials and devices. Nanoscale materials attract considerable interest because of their unusual properties and potential for practical applications. Most of the activity in this field is focused on the synthesis of homogeneous nanoparticles from metals, metal oxides, semiconductors, and polymers. It is well recognized that properties of nanoparticles can be further enhanced if they are made as hybrid structures. This program is concerned with the synthesis, characterization, and application of such hybrid structures termed AHNs. AHNs are composed of a homogeneous core and several caps of different materials deposited on its surface (Fig. 1). Combined properties of the core and the caps as well as new properties that arise from core-cap and cap-cap interactions render AHNs multifunctional. In addition, specific chemical reactivity of the caps enables directional self-assembly of AHNs into complex architectures that are not possible with only spherical nanoparticles.

  20. Simulations of defect spin qubits in piezoelectric semiconductors

    Science.gov (United States)

    Seo, Hosung

    In recent years, remarkable advances have been reported in the development of defect spin qubits in semiconductors for solid-state quantum information science and quantum metrology. Promising spin qubits include the nitrogen-vacancy center in diamond, dopants in silicon, and the silicon vacancy and divacancy spins in silicon carbide. In this talk, I will highlight some of our recent efforts devoted to defect spin qubits in piezoelectric wide-gap semiconductors for potential applications in mechanical hybrid quantum systems. In particular, I will describe our recent combined theoretical and experimental study on remarkably robust quantum coherence found in the divancancy qubits in silicon carbide. We used a quantum bath model combined with a cluster expansion method to identify the microscopic mechanisms behind the unusually long coherence times of the divacancy spins in SiC. Our study indicates that developing spin qubits in complex crystals with multiple types of atom is a promising route to realize strongly coherent hybrid quantum systems. I will also discuss progress and challenges in computational design of new spin defects for use as qubits in piezoelectric crystals such as AlN and SiC, including a new defect design concept using large metal ion - vacancy complexes. Our first principles calculations include DFT computations using recently developed self-consistent hybrid density functional theory and large-scale many-body GW theory. This work was supported by the National Science Foundation (NSF) through the University of Chicago MRSEC under Award Number DMR-1420709.

  1. Semiconductor lasers stability, instability and chaos

    CERN Document Server

    Ohtsubo, Junji

    2017-01-01

    This book describes the fascinating recent advances made concerning the chaos, stability and instability of semiconductor lasers, and discusses their applications and future prospects in detail. It emphasizes the dynamics in semiconductor lasers by optical and electronic feedback, optical injection, and injection current modulation. Applications of semiconductor laser chaos, control and noise, and semiconductor lasers are also demonstrated. Semiconductor lasers with new structures, such as vertical-cavity surface-emitting lasers and broad-area semiconductor lasers, are intriguing and promising devices. Current topics include fast physical number generation using chaotic semiconductor lasers for secure communication, development of chaos, quantum-dot semiconductor lasers and quantum-cascade semiconductor lasers, and vertical-cavity surface-emitting lasers. This fourth edition has been significantly expanded to reflect the latest developments. The fundamental theory of laser chaos and the chaotic dynamics in se...

  2. Similarities and differences of recent hybrid pixel detectors for X-ray and high energy physics developed at the Paul Scherrer Institut

    Science.gov (United States)

    Tinti, G.; Bergamaschi, A.; Cartier, S.; Dinapoli, R.; Greiffenberg, D.; Horisberger, R.; Johnson, I.; Jungmann-Smith, J. H.; Mezza, D.; Mozzanica, A.; Schmitt, B.; Shi, X.

    2015-04-01

    Hybrid pixel detectors are being developed for both photon science and high energy physics. The article will cover similarities and differences in pixel detectors for both applications using two of the pixel detectors developed at the Paul Scherrer Institute (Switzerland) as examples: the EIGER photon counting detector and the psi46dig chip, which has been developed for the Compact Muon Solenoid (CMS) tracking pixel detector upgrade. EIGER is a single photon counting hybrid pixel detector for applications at synchrotron light sources in the energy range from a few to 25 keV. It is characterized by a small pixel size (75 × 75 μm2), high count rate capability (106 counts/pixel/s) and very high data rate, which reaches 6 Gb/s for a 256 × 256 pixel chip. The CMS pixel detector is designed to provide charge information from the pixels in the harsh radiation environment at the Large Hadron Collider. The short time between bunches of 25 ns and the high event rate at luminosity up to 2 × 1034cm-2s-1 require a detector with high hit efficiency, with good timing resolution and the ability to retain timestamp information for the hits. The readout architecture is based on the transfer of hits from the pixels to the periphery, where the trigger validation is performed before data transfer. The data rates of the digitized output reach 160 Mb/s for a 52×80 pixel chip.The specific timing and rate requirements for the detectors, the analog performances (minimum threshold and noise), the power consumption and the radiation hardness will be compared. An overview on future developments based on mutual learning and common solutions will be discussed.

  3. Semiconductor micropattern pixel detectors a review of the beginnings

    CERN Document Server

    Heijne, Erik H M

    2001-01-01

    The innovation in monolithic and hybrid semiconductor 'micropattern' or 'reactive' pixel detectors for tracking in particle physics was actually to fit logic and pulse processing electronics with µW power on a pixel area of less than 0.04 mm2, retaining the characteristics of a traditional nuclear amplifier chain. The ns timing precision in conjunction with local memory and logic operations allowed event selection at > 10 MHz rates with unambiguous track reconstruction even at particle multiplicities > 10 cm-2. The noise in a channel was ~100 e- r.m.s. and enabled binary operation with random noise 'hits' at a level 30 Mrad, respectively.

  4. Photoreflectance Characterization of Semiconductors

    Science.gov (United States)

    Bhimnathwala, Hemant Ghanshyamdas

    Photoreflectance technique has been used as a non-destructive probe of surface photo-voltage in doped and semi-insulating semiconductors. A system used to measure the photoreflectance spectra near the fundamental gap of GaAs and InP has been described. Measurements as a function of pump intensity on n and p type GaAs were used to infer the carrier dynamics leading to change in the surface electric field. Measurements indicate that the surface of GaAs consists of hole traps at the surface in addition to recombination states. This is confirmed by spectroscopic studies carried out by varying the pump modulation frequency at fixed temperatures and the measurements show that the hole trap has an activation energy of 0.29 eV and has an emission time of 0.175 +/- 0.002 msec. at room temperature. In semi-insulating GaAs, it is expected that there is no surface electric field at equilibrium due to pinning at the surface and large concentration of deep defect EL2. Electromodulation, in this case proceeds via preferential trapping of holes at the surface. This is supported by measurements carried out as a function of pump intensity and on wafers having different carbon concentrations. Analysis of carrier dynamics in semi-insulating GaAs is much simplified by use of Nd:YAG laser (instead of a HeNe laser) as a source of pump beam. A sub-band -gap excitation generates mainly excess electrons and the Poisson's equation can be integrated once to find the surface electric field. Numerical integration yields the surface photovoltage. It is shown that this technique is sensitive to the the surface state density and relatively insensitive to bulk properties. It has been applied to study the effect of various chemical reactants on the surface state density. In many PR spectra, features at energies less than the gap energy are observed. These are ascribed to shallow acceptors unrelated to carbon, which was the dominant acceptor in these materials. It is proposed that the electric field

  5. Physics of semiconductor laser devices

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, G.H.B.

    1980-01-01

    The physics of the semiconductor laser is studied. The basic phenomena that control the operation of the device are analyzed and described in considerable detail. The treatment has been keyed particularly to fundamental concepts and kept general in order to avoid being overtaken by events. The range of phenomena in a semiconductor laser involves a number of scientific disciplines. To cater for the reader who is not already a specialist in all of these the author has endeavoured, in the chapters on fundamental behaviour, to provide in a readable form the minimum background that is needed to understand the more specialist part of the text. As an introduction a general review is given of the whole range of semiconductor laser devices that now exist, the technology involved in their fabrication, the factors that determine their reliability, and their possible role in integrated systems.

  6. Thiophene-Based Organic Semiconductors.

    Science.gov (United States)

    Turkoglu, Gulsen; Cinar, M Emin; Ozturk, Turan

    2017-10-24

    Thiophene-based π-conjugated organic small molecules and polymers are the research subject of significant current interest owing to their potential use as organic semiconductors in material chemistry. Despite simple and similar molecular structures, the hitherto reported properties of thiophene-based organic semiconductors are rather diverse. Design of high performance organic semiconducting materials requires a thorough understanding of inter- and intra-molecular interactions, solid-state packing, and the influence of both factors on the charge carrier transport. In this chapter, thiophene-based organic semiconductors, which are classified in terms of their chemical structures and their structure-property relationships, are addressed for the potential applications as organic photovoltaics (OPVs), organic field-effect transistors (OFETs) and organic light emitting diodes (OLEDs).

  7. High pressure semiconductor physics I

    CERN Document Server

    Willardson, R K; Paul, William; Suski, Tadeusz

    1998-01-01

    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise indeed that this tra...

  8. Optical Spectroscopy of Hybrid Semiconductor Quantum Dots and Metal Nanoparticles

    Science.gov (United States)

    2014-11-07

    a picture reformation with -35% brightness and 35% contrast after the dark and bright images of figure 3 (c) were inverted . The inset image in...be ~3.7×10-3 nm-2 by the inverted image of the figure 3 (c). To analyze the coupling distance from the layer of Au nanoparticles on the quartz plate...Quinton Rice, and Mr. Anderson Hayes visited high school science classrooms , and presented 2 science-oriented talks concerning the types of energy

  9. Observation of giant magnetoresistances in hybrid semiconductor/ferromagnetic devices

    Science.gov (United States)

    Overend, N.; Nogaret, A.; Gallagher, B. L.; Main, P. C.; Henini, M.; Wirtz, R.; Newbury, R.; Marrows, C. H.; Howson, M. A.; Beaumont, S. P.

    1998-01-01

    We have investigated the magnetoresistance (MR) of heterostructures containing near-surface two-dimensional electron systems subject to periodic, sign-alternating magnetic fields produced by arrays of sub-micron ferromagnetic stripes fabricated on the device surface. We observe giant magnetoresistances (GMR) with up to a ˜ 1000% increase in resistance on application of external fields of only ˜ 100 mT at a temperature of 4 K and ˜ 1% at 300 K. The MR is strongly dependent upon the angle between the external field and the stripes and it can also be strongly hysteretic. This MR arises from the electrons propagating in open 'snake' orbits along the lines of zero magnetic field. Such devices may have possible applications as magnetic memories and sensors.

  10. Hybrid tracking detector based on semiconductor and gas technologies

    Science.gov (United States)

    Bashindzhagyan, George; Korotkova, Natalia; Romaniouk, Anatoli; Sinev, Nikolai; Tikhomirov, Vladimir

    2017-10-01

    New Silicon-Gas Pixel Detector (SiGPD) is the result of the further development already proposed Gas-Pixel Detector (GPD). The only disadvantage of GPD was the uncertainty of the particle arriving time. The problem can be solved by additional silicon pixels implementation inside existed electronic chip epitaxial layer during regular chip production. The cost of new Si-Gas Pixel Detector remains practically the same. The new detectors have self-triggering properties and can be used for a first level trigger generation in the particle physics experiments and for many other applications.

  11. Semiconductor device physics and simulation

    CERN Document Server

    Yuan, J S

    1998-01-01

    This volume provides thorough coverage of modern semiconductor devices -including hetero- and homo-junction devices-using a two-dimensional simulator (MEDICI) to perform the analysis and generate simulation results Each device is examined in terms of dc, ac, and transient simulator results; relevant device physics; and implications for design and analysis Two hundred forty-four useful figures illustrate the physical mechanisms and characteristics of the devices simulated Comprehensive and carefully organized, Semiconductor Device Physics and Simulation is the ideal bridge from device physics to practical device design

  12. Optical coherent control in semiconductors

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher

    2001-01-01

    The developments with coherent control (CC) techniques in optical spectroscopy have recently demonstrated population control and coherence manipulations when the induced optical phase is explored with phase-locked laser pulses. These and other developments have been guiding the new research field...... of quantum control including the recent applications to semiconductors and nanostructures. We study the influence of inhomogeneous broadening in semiconductors on CC results. Photoluminescence (PL) and the coherent emission in four-wave mixing (FWM) is recorded after resonant excitation with phase-locked...

  13. Semiconductor lasers and herterojunction leds

    CERN Document Server

    Kressel, Henry

    2012-01-01

    Semiconductor Lasers and Heterojunction LEDs presents an introduction to the subject of semiconductor lasers and heterojunction LEDs. The book reviews relevant basic solid-state and electromagnetic principles; the relevant concepts in solid state physics; and the p-n junctions and heterojunctions. The text also describes stimulated emission and gain; the relevant concepts in electromagnetic field theory; and the modes in laser structures. The relation between electrical and optical properties of laser diodes; epitaxial technology; binary III-V compounds; and diode fabrication are also consider

  14. Semiconductors and semimetals epitaxial microstructures

    CERN Document Server

    Willardson, Robert K; Beer, Albert C; Gossard, Arthur C

    1994-01-01

    Newly developed semiconductor microstructures can now guide light and electrons resulting in important consequences for state-of-the-art electronic and photonic devices. This volume introduces a new generation of epitaxial microstructures. Special emphasis has been given to atomic control during growth and the interrelationship between the atomic arrangements and the properties of the structures.Key Features* Atomic-level control of semiconductor microstructures* Molecular beam epitaxy, metal-organic chemical vapor deposition* Quantum wells and quantum wires* Lasers, photon(IR)detectors, heterostructure transistors

  15. Introduction to semiconductor manufacturing technology

    CERN Document Server

    2012-01-01

    IC chip manufacturing processes, such as photolithography, etch, CVD, PVD, CMP, ion implantation, RTP, inspection, and metrology, are complex methods that draw upon many disciplines. [i]Introduction to Semiconductor Manufacturing Technologies, Second Edition[/i] thoroughly describes the complicated processes with minimal mathematics, chemistry, and physics; it covers advanced concepts while keeping the contents accessible to readers without advanced degrees. Designed as a textbook for college students, this book provides a realistic picture of the semiconductor industry and an in-depth discuss

  16. Wide band gap semiconductor templates

    Energy Technology Data Exchange (ETDEWEB)

    Arendt, Paul N. (Los Alamos, NM); Stan, Liliana (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM); DePaula, Raymond F. (Santa Fe, NM); Usov, Igor O. (Los Alamos, NM)

    2010-12-14

    The present invention relates to a thin film structure based on an epitaxial (111)-oriented rare earth-Group IVB oxide on the cubic (001) MgO terminated surface and the ion-beam-assisted deposition ("IBAD") techniques that are amendable to be over coated by semiconductors with hexagonal crystal structures. The IBAD magnesium oxide ("MgO") technology, in conjunction with certain template materials, is used to fabricate the desired thin film array. Similarly, IBAD MgO with appropriate template layers can be used for semiconductors with cubic type crystal structures.

  17. Modeling of semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Mørk, Jesper; Bischoff, Svend; Berg, Tommy Winther

    We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed.......We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed....

  18. Organic semiconductors in sensor applications

    CERN Document Server

    Malliaras, George; Owens, Róisín

    2008-01-01

    Organic semiconductors offer unique characteristics such as tunability of electronic properties via chemical synthesis, compatibility with mechanically flexible substrates, low-cost manufacturing, and facile integration with chemical and biological functionalities. These characteristics have prompted the application of organic semiconductors and their devices in physical, chemical, and biological sensors. This book covers this rapidly emerging field by discussing both optical and electrical sensor concepts. Novel transducers based on organic light-emitting diodes and organic thin-film transistors, as well as systems-on-a-chip architectures are presented. Functionalization techniques to enhance specificity are outlined, and models for the sensor response are described.

  19. Influence of phonons on semiconductor quantum emission

    Energy Technology Data Exchange (ETDEWEB)

    Feldtmann, Thomas

    2009-07-06

    A microscopic theory of interacting charge carriers, lattice vibrations, and light modes in semiconductor systems is presented. The theory is applied to study quantum dots and phonon-assisted luminescence in bulk semiconductors and heterostructures. (orig.)

  20. Fundamentals of semiconductors physics and materials properties

    CERN Document Server

    Yu, Peter Y

    2005-01-01

    Provides detailed explanations of the electronic, vibrational, transport, and optical properties of semiconductors. This textbook emphasizes understanding the physical properties of Si and similar tetrahedrally coordinated semiconductors and features an extensive collection of tables of material parameters, figures, and problems.