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Sample records for cdte semiconductor detectors

  1. Design of a high-resolution small-animal SPECT-CT system sharing a CdTe semiconductor detector

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Hyun-Ju; Lee, Young-Jin; Lee, Seung-Wan; Cho, Hyo-Min; Choi, Yu-Na; Kim, Hee-Joung [Yonsei University, Wonju (Korea, Republic of)

    2012-07-15

    A single photon emission computed tomography (SPECT) system with a co-registered X-y computed tomography (CT) system allows the convergence of functional information and morphologic information. The localization of radio pharmaceuticals on a SPECT can be enhanced by combining the SPECT with an anatomical modality, such as X-ray CT. Gamma-ray imaging for nuclear medicine devices and X-ray imaging systems for diagnostics has recently been developed based on semiconductor detectors, and semiconductor detector materials such as cadmium telluride (CdTe) or cadmium zinc telluride (CZT) are available for both X-ray and gamma-ray systems for small animal imaging. CdTe or CZT detectors provide strong absorption and high detection efficiency of high energy X-ray and gamma-ray photons because of their large atomic numbers. In this study, a pinhole collimator SPECT system sharing a cadmium telluride (CdTe) detector with a CT was designed. The GEANT4 application for tomographic emission (GATE) v.6.1 was used for the simulation. The pinhole collimator was designed to obtain a high spatial resolution of the SPECT system. The acquisition time for each projection was 40 seconds, and 60 projections were obtained for tomographic image acquisition. The reconstruction was performed using ordered subset expectation maximization (OS-EM) algorithms. The sensitivity and the spatial resolution were measured on the GATE simulation to evaluate the system characteristics. The spatial resolution of the system calculated from the FWHM of Gaussian fitted PSF curve was 0.69 mm, and the sensitivity of the system was measured to be 0.354 cps/kBq by using a Tc-99m point source of 1 MBq for 800 seconds. A phantom study was performed to verify the design of the dual imaging modality system. The system will be built as designed, and it can be applied as a pre-clinical imaging system.

  2. Progress in the Development of CdTe and CdZnTe Semiconductor Radiation Detectors for Astrophysical and Medical Applications

    Directory of Open Access Journals (Sweden)

    Anna Maria Mancini

    2009-05-01

    Full Text Available Over the last decade, cadmium telluride (CdTe and cadmium zinc telluride (CdZnTe wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si and germanium (Ge, CdTe and CdZnTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact and reliable detection systems. In this paper, we review the current status of research in the development of CdTe and CdZnTe detectors by a comprehensive survey on the material properties, the device characteristics, the different techniques for improving the overall detector performance and some major applications. Astrophysical and medical applications are discussed, pointing out the ongoing Italian research activities on the development of these detectors.

  3. Progress in the Development of CdTe and CdZnTe Semiconductor Radiation Detectors for Astrophysical and Medical Applications.

    Science.gov (United States)

    Sordo, Stefano Del; Abbene, Leonardo; Caroli, Ezio; Mancini, Anna Maria; Zappettini, Andrea; Ubertini, Pietro

    2009-01-01

    Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si) and germanium (Ge), CdTe and CdZnTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact and reliable detection systems. In this paper, we review the current status of research in the development of CdTe and CdZnTe detectors by a comprehensive survey on the material properties, the device characteristics, the different techniques for improving the overall detector performance and some major applications. Astrophysical and medical applications are discussed, pointing out the ongoing Italian research activities on the development of these detectors.

  4. Hard-X and gamma-ray imaging detector for astrophysics based on pixelated CdTe semiconductors

    Science.gov (United States)

    Gálvez, J.-L.; Hernanz, M.; Álvarez, L.; Artigues, B.; Ullán, M.; Lozano, M.; Pellegrini, G.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2016-01-01

    Stellar explosions are astrophysical phenomena of great importance and interest. Instruments with high sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators. In order to achieve the needed performance, a hard-X and gamma-ray imaging detector with mm spatial resolution and large enough efficiency is required. We present a detector module which consists of a single CdTe crystal of 12.5 × 12.5mm 2 and 2mm thick with a planar cathode and with the anode segmented in an 11x11 pixel array with a pixel pitch of 1 mm attached to the readout chip. Two possible detector module configurations are considered: the so-called Planar Transverse Field (PTF) and the Parallel Planar Field (PPF). The combination of several modules in PTF or PPF configuration will achieve the desired performance of the imaging detector. The sum energy resolution of all pixels of the CdTe module measured at 122 keV and 356 keV is 3.8% and 2% respectively, in the following operating conditions: PPF irradiation, bias voltage -500 V and temperature -10̂ C.

  5. Semiconductor Detectors; Detectores de Semiconductores

    Energy Technology Data Exchange (ETDEWEB)

    Cortina, E.

    2007-07-01

    Particle detectors based on semiconductor materials are among the few devices used for particle detection that are available to the public at large. In fact we are surrounded by them in our daily lives: they are used in photoelectric cells for opening doors, in digital photographic and video camera, and in bar code readers at supermarket cash registers. (Author)

  6. Study on temperature coefficient of CdTe detector used for X-rays detection

    CERN Document Server

    Guo, Si-Ming; Zhang, Jian; Li, Xu-Fang; Liu, Cong-Zhan; Zhang, Shuai; Li, Cheng-Ze; Huo, Bin-Bin; Liao, Zhen-Yu

    2016-01-01

    The temperature of the working environment is a key factor in determining the properties of semiconductor detectors, and it affects the absolute accuracy and stability of the standard detector. In order to determine the temperature coefficient of CdTe detector used for X-rays detection, a precise temperature control system was designed. In this experiment, detectors and radiographic source were set inside the thermostat with temperature of 0-40 Celsius degree, so that the temperature can be regulated for the test of the temperature coefficient of CdTe detector. Studies had shown that, with the increase of the temperature, the energy resolution and detection efficiency of the CdTe detector would deteriorate, and under 10 Celsius degree the detectors have better performance with the 8 keV X-rays.

  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. Improvement of the energy resolution of CdTe detectors by pulse height correction from waveform

    CERN Document Server

    Kikawa, T; Hiraki, T; Nakaya, T

    2011-01-01

    Semiconductor detectors made of CdTe crystal have high gamma-ray detection efficiency and are usable at room temperature. However, the energy resolution of CdTe detectors for MeV gamma-rays is rather poor because of the significant hole trapping effect. We have developed a method to improve the energy resolution by correcting the pulse height using the waveform of the signal and achieved 2.0% (FWHM) energy resolution for 662keV gamma-rays. Best energy resolution was achieved at temperatures between -10 degrees C and 0 degrees C.

  9. The use of CdTe detectors for dental X-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcus Aurelio P. dos; Fragoso, Maria da Conceicao F.; Oliveira, Mercia L.; Lima, Ricardo de A.; Hazin, Clovis A. [Centro Regional de Ciencias Nucleares (CRCN/CNEN-PE), Recife, PE (Brazil)]. E-mails: masantos@cnen.gov.br; mariacc05@yahoo.com.br; mercial@cnen.gov.br; ralima@cnen.gov.br; chazin@cnen.gov.br

    2007-07-01

    he cadmium telluride (CdTe) semiconductor detector provides high detection efficiency for use in the diagnostic x-rays energy range, because of the high atomic number and high density of the crystal. Moreover, it has the great advantage of working at room temperature, in contrast to the germanium detector, which operates in liquid nitrogen temperature. The CdTe detector has been utilized in diagnostic x-ray spectroscopy, but only scarce information about its use in dental X-ray beams has been published. In this way, a portable 3x3x1 mm{sup 3} CdTe solid state detector (XR-100T CdTe by Amptek, Inc.) with tungsten pinhole collimators, alignment device and associated software was utilized in this work for measuring the photon spectra in the dental x-ray kVp range. A single-phase dental unit with adjustable kVp and mA was employed and the x-ray spectra were experimentally determined at 50, 60 and 70 kVp with 0.5 mA tube current. The pulse height distribution obtained with this detector, however, does not represent the 'true' photon spectra. For this reason, a stripping procedure was implemented to correct the distribution in order to determine the real photon spectra. The x-ray spectra obtained with the CdTe detector were compared with the ones measured with a high-purity germanium detector (EGP200-13-TR by Eurisys Mesures). The reasonable agreement between the results obtained with both detectors for the 50 to 70 keV range show that CdTe detectors can be utilized for dental x-ray spectrometry. (author)

  10. High-resolution CdTe detectors with application to various fields (Conference Presentation)

    Science.gov (United States)

    Takeda, Shin'ichiro; Orita, Tadashi; Arai, Yasuo; Sugawara, Hirotaka; Tomaru, Ryota; Katsuragawa, Miho; Sato, Goro; Watanabe, Shin; Ikeda, Hirokazu; Takahashi, Tadayuki; Furenlid, Lars R.; Barber, H. Bradford

    2016-10-01

    High-quality CdTe semiconductor detectors with both fine position resolution and high energy resolution hold great promise to improve measurement in various hard X-ray and gamma-ray imaging fields. ISAS/JAXA has been developing CdTe imaging detectors to meet scientific demands in latest celestial observation and severe environmental limitation (power consumption, vibration, radiation) in space for over 15 years. The energy resolution of imaging detectors with a CdTe Schottky diode of In/CdTe/Pt or Al/CdTe/Pt contact is a highlight of our development. We can extremely reduce a leakage current of devises, meaning it allows us to supply higher bias voltage to collect charges. The 3.2cm-wide and 0.75mm-thick CdTe double-sided strip detector with a strip pitch of 250 µm has been successfully established and was mounted in the latest Japanese X-ray satellite. The energy resolution measured in the test on ground was 2.1 keV (FWHM) at 59.5 keV. The detector with much finer resolution of 60 µm is ready, and it was actually used in the FOXSI rocket mission to observe hard X-ray from the sun. In this talk, we will focus on our research activities to apply space sensor technologies to such various imaging fields as medical imaging. Recent development of CdTe detectors, imaging module with pinhole and coded-mask collimators, and experimental study of response to hard X-rays and gamma-rays are presented. The talk also includes research of the Compton camera which has a configuration of accumulated Si and CdTe imaging detectors.

  11. Growth and fabrication method of CdTe and its performance as a radiation detector

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hyojeong [Korea Atomic Energy Research Institute, Jeong-eup (Korea, Republic of); Sungkyunkwan University, Suwon (Korea, Republic of); Jeong, Manhee; Kim, Hansoo; Kim, Youngsoo; Ha, Jangho [Korea Atomic Energy Research Institute, Jeong-eup (Korea, Republic of); Chai, Jong-Seo [Sungkyunkwan University, Suwon (Korea, Republic of)

    2015-01-15

    A CdTe crystal ingot doped with 2000 ppm of Cl was grown by using the low-pressure Bridgman (LPB) method at the Korea Atomic Energy Research Institute (KAERI). A Semiconductor detector as a radiation detection sensor with a size of 7 (W) x 6.5 (D) x 2 (H) mm{sup 3} was fabricated from the CdTe ingot. In addition, the properties of the CdTe sample were observed through four kinds of experiments to analyze its performance. The resistivity was obtained as 1.41 x 10{sup 10} Ωcm by using a Keithley 6517A high-precision electrometer. The mobility-life time products for electrons and holes were 3.137 x 10{sup -}'4 cm{sup 2}/V and 4.868 x 10{sup -5} cm{sup 2}/V, respectively. Finally, we achieved a 16.8% energy resolution at 59.5 keV for the {sup 241}Am gamma-ray source. The CdTe semiconductor detector grown at KAERI has a performance good enough to detect low-energy gamma-rays.

  12. CdTe detector efficiency calibration using thick targets of pure and stable compounds

    Science.gov (United States)

    Chaves, P. C.; Taborda, A.; Reis, M. A.

    2012-02-01

    Quantitative PIXE measurements require perfectly calibrated set-ups. Cooled CdTe detectors have good efficiency for energies above those covered by Si(Li) detectors and turn on the possibility of studying K X-rays lines instead of L X-rays lines for medium and eventually heavy elements, which is an important advantage in various cases, if only limited resolution systems are available in the low energy range. In this work we present and discuss spectra from a CdTe semiconductor detector covering the energy region from Cu (K α1 = 8.047 keV) to U (K α1 = 98.439 keV). Pure thick samples were irradiated with proton beams at the ITN 3.0 MV Tandetron accelerator in the High Resolution High Energy PIXE set-up. Results and the application to the study of a Portuguese Ossa Morena region Dark Stone sample are presented in this work.

  13. Digital pulse-shape processing for CdTe detectors

    CERN Document Server

    Bargholtz, C; Maartensson, L; Wachtmeister, S

    2001-01-01

    CdTe detectors suffer from low photo-peak efficiency and poor energy resolution. These problems are due to the drift properties of charge carriers in CdTe where particularly the holes have small mobility and trapping time. This is reflected in the amplitude and the shape of the detector output. To improve this situation a digital method is introduced where a sampling ADC is used to make a detailed measurement of the time evolution of the pulse. The measured pulse shape is fitted with a model. For the detector under study a model taking hole trapping into account significantly improves the photo-peak efficiency. The description of the hole component is, however, not fully satisfactory since for pulses with a large hole contribution a broadening of the full-energy peak occurs. Allowing for inhomogeneities in the detector material within the model partially remedies this deficiency.

  14. Digital signal processing for CdTe detectors using VXIbus data collection systems

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Daiji; Takahashi, Hiroyuki; Kurahashi, Tomohiko; Iguchi, Tetsuo; Nakazawa, Masaharu

    1996-07-01

    Recently fast signal digitizing technique has been developed, and signal waveforms with very short time periods can be obtained. In this paper, we analyzed each measured pulse which was digitized by an apparatus of this kind, and tried to improve an energy resolution of a CdTe semiconductor detector. The result of the energy resolution for {sup 137}Cs 662 keV photopeak was 13 keV. Also, we developed a fast data collection system based on VXIbus standard, and the counting rate on this system was obtained about 50 counts per second. (author)

  15. Semiconductor detectors for soft γ-ray astrophysics

    Science.gov (United States)

    Lebrun, François

    2006-07-01

    The study of γ-ray bursts, compact objects, nucleosynthesis and supernova remnants triggers the most interest today in the soft γ-ray domain. These topics have various experimental requirements with emphasis either on imaging or on spectroscopy. Recent progress has shown the great potential of semiconductor detectors for both applications at the expense of classical scintillators such as NaI or CsI. They also gave insight into their long-term in-orbit behaviour. Room temperature semiconductor detectors, particularly CdTe and CdZnTe, are confirmed as the best choice for imaging applications. As illustrated by the INTEGRAL/ISGRI camera, the CdTe stability is better than expected; its internal background is comparable to that of scintillators, and the spectroscopic degradation in space is slow with a lifetime of about 40 years on an eccentric orbit. Cooled germanium detectors offer the best energy resolution but degrade more rapidly under the cosmic-ray irradiation. However, the INTEGRAL/SPI spectrometer has demonstrated that periodic in-orbit annealings, allowing for a full recovery of the energy resolution, can maintain the spectroscopic performance over several years. Most future projects, focussing on coded mask or Compton telescopes, will take advantage of the semiconductor technology, particularly that related to the ambient temperature detectors.

  16. Modelling semiconductor pixel detectors

    CERN Document Server

    Mathieson, K

    2001-01-01

    expected after 200 ps in most cases. The effect of reducing the charge carrier lifetime and examining the charge collection efficiency has been utilised to explore how these detectors would respond in a harsh radiation environment. It is predicted that over critical carrier lifetimes (10 ps to 0.1 ns) an improvement of 40 % over conventional detectors can be expected. This also has positive implications for fabricating detectors, in this geometry, from materials which might otherwise be considered substandard. An analysis of charge transport in CdZnTe pixel detectors has been performed. The analysis starts with simulation studies into the formation of contacts and their influence on the internal electric field of planar detectors. The models include a number of well known defect states and these are balanced to give an agreement with a typical experimental I-V curve. The charge transport study extends to the development of a method for studying the effect of charge sharing in highly pixellated detectors. The ...

  17. Performance characteristics of CdTe drift ring detector

    Science.gov (United States)

    Alruhaili, A.; Sellin, P. J.; Lohstroh, A.; Veeramani, P.; Kazemi, S.; Veale, M. C.; Sawhney, K. J. S.; Kachkanov, V.

    2014-03-01

    CdTe and CdZnTe material is an excellent candidate for the fabrication of high energy X-ray spectroscopic detectors due to their good quantum efficiency and room temperature operation. The main material limitation is associated with the poor charge transport properties of holes. The motivation of this work is to investigate the performance characteristics of a detector fabricated with a drift ring geometry that is insensitive to the transport of holes. The performance of a prototype Ohmic CdTe drift ring detector fabricated by Acrorad with 3 drift rings is reported; measurements include room temperature current voltage characteristics (IV) and spectroscopic performance. The data shows that the energy resolution of the detector is limited by leakage current which is a combination of bulk and surface leakage currents. The energy resolution was studied as a function of incident X-ray position with an X-ray microbeam at the Diamond Light Source. Different ring biasing schemes were investigated and the results show that by increasing the lateral field (i.e. the bias gradient across the rings) the active area, evaluated by the detected count rate, increased significantly.

  18. Pixelized M-pi-n CdTe detector coupled to Medipix2 readout chip

    CERN Document Server

    Kalliopuska, J; Penttila, R; Andersson, H; Nenonen, S; Gadda, A; Pohjonen, H; Vanttajac, I; Laaksoc, P; Likonen, J

    2011-01-01

    We have realized a simple method for patterning an M-pi-n CdTe diode with a deeply diffused pn-junction, such as indium anode on CdTe. The method relies on removing the semiconductor material on the anode-side of the diode until the physical junction has been reached. The pixelization of the p-type CdTe diode with an indium anode has been demonstrated by patterning perpendicular trenches with a high precision diamond blade and pulsed laser. Pixelization or microstrip pattering can be done on both sides of the diode, also on the cathode-side to realize double sided detector configuration. The article compares the patterning quality of the diamond blade process, pulsed pico-second and femto-second lasers processes. Leakage currents and inter-strip resistance have been measured and are used as the basis of the comparison. Secondary ion mass spectrometry (SIMS) characterization has been done for a diode to define the pn-junction depth and to see the effect of the thermal loads of the flip-chip bonding process. Th...

  19. Semiconductor X-ray detectors

    CERN Document Server

    Lowe, Barrie Glyn

    2014-01-01

    Identifying and measuring the elemental x-rays released when materials are examined with particles (electrons, protons, alpha particles, etc.) or photons (x-rays and gamma rays) is still considered to be the primary analytical technique for routine and non-destructive materials analysis. The Lithium Drifted Silicon (Si(Li)) X-Ray Detector, with its good resolution and peak to background, pioneered this type of analysis on electron microscopes, x-ray fluorescence instruments, and radioactive source- and accelerator-based excitation systems. Although rapid progress in Silicon Drift Detectors (SDDs), Charge Coupled Devices (CCDs), and Compound Semiconductor Detectors, including renewed interest in alternative materials such as CdZnTe and diamond, has made the Si(Li) X-Ray Detector nearly obsolete, the device serves as a useful benchmark and still is used in special instances where its large, sensitive depth is essential. Semiconductor X-Ray Detectors focuses on the history and development of Si(Li) X-Ray Detect...

  20. A pixellated gamma-camera based on CdTe detectors clinical interests and performances

    CERN Document Server

    Chambron, J; Eclancher, B; Scheiber, C; Siffert, P; Hage-Ali, M; Regal, R; Kazandjian, A; Prat, V; Thomas, S; Warren, S; Matz, R; Jahnke, A; Karman, M; Pszota, A; Németh, L

    2000-01-01

    A mobile gamma camera dedicated to nuclear cardiology, based on a 15 cmx15 cm detection matrix of 2304 CdTe detector elements, 2.83 mmx2.83 mmx2 mm, has been developed with a European Community support to academic and industrial research centres. The intrinsic properties of the semiconductor crystals - low-ionisation energy, high-energy resolution, high attenuation coefficient - are potentially attractive to improve the gamma-camera performances. But their use as gamma detectors for medical imaging at high resolution requires production of high-grade materials and large quantities of sophisticated read-out electronics. The decision was taken to use CdTe rather than CdZnTe, because the manufacturer (Eurorad, France) has a large experience for producing high-grade materials, with a good homogeneity and stability and whose transport properties, characterised by the mobility-lifetime product, are at least 5 times greater than that of CdZnTe. The detector matrix is divided in 9 square units, each unit is composed ...

  1. CdTe detector efficiency calibration using thick targets of pure and stable compounds

    Energy Technology Data Exchange (ETDEWEB)

    Chaves, P.C.; Taborda, A., E-mail: ataborda@itn.pt; Reis, M.A.

    2012-02-15

    Quantitative PIXE measurements require perfectly calibrated set-ups. Cooled CdTe detectors have good efficiency for energies above those covered by Si(Li) detectors and turn on the possibility of studying K X-rays lines instead of L X-rays lines for medium and eventually heavy elements, which is an important advantage in various cases, if only limited resolution systems are available in the low energy range. In this work we present and discuss spectra from a CdTe semiconductor detector covering the energy region from Cu (K{sub {alpha}1} = 8.047 keV) to U (K{sub {alpha}1} = 98.439 keV). Pure thick samples were irradiated with proton beams at the ITN 3.0 MV Tandetron accelerator in the High Resolution High Energy PIXE set-up. Results and the application to the study of a Portuguese Ossa Morena region Dark Stone sample are presented in this work.

  2. Hybrid anode for semiconductor radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ge; Bolotnikov, Aleksey E; Camarda, Guiseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B

    2013-11-19

    The present invention relates to a novel hybrid anode configuration for a radiation detector that effectively reduces the edge effect of surface defects on the internal electric field in compound semiconductor detectors by focusing the internal electric field of the detector and redirecting drifting carriers away from the side surfaces of the semiconductor toward the collection electrode(s).

  3. Large dynamic range 64-channel ASIC for CZT or CdTe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Glasser, F. E-mail: francis.glasser@cea.fr; Villard, P.; Rostaing, J.P.; Accensi, M.; Baffert, N.; Girard, J.L

    2003-08-21

    We present a customized 64-channel ASIC, named ALIX, developed in a 0.8 {mu}m CMOS technology. This circuit is dedicated to measure charges from semi-conductor X-ray detectors like Cadmium Zinc Telluride (CZT) or Cadmium Telluride CdTe. The specificity of ALIX is to be able to measure charges over a very large dynamic range (from 10 fC to 3 nC), and to store eight measurements in a very short time (from every 250 ns to a few ms). Up to eight images are stored inside the ASIC and each image can be read out in 64 {mu}s. A new acquisition sequence can then be started. Two analog readouts are available, one for the X-ray signal and one for the offset and afterglow measurement in case of pulsed X-rays. The outputs are converted into digital values by two off-chip 14 bits Analog-to-Digital Converters (ADC). A first version of ALIX has been tested with CZT and CdTe detectors under high-energy pulsed X-ray photons (20 MeV, 60 ns pulses every 250 ns). We will present the different results of linearity and signal-to-noise ratio. A second version of ALIX has been designed with some corrections. Electrical tests performed on 85 ASICS showed that the corrections were successful. We are now able to integrate them behind a 64x32 pixels 1 mm pitch CZT detector. Such an ASIC could also be used for strip detectors where a large dynamic range and a fast response are necessary.

  4. Large dynamic range 64-channel ASIC for CZT or CdTe detectors

    Science.gov (United States)

    Glasser, F.; Villard, P.; Rostaing, J. P.; Accensi, M.; Baffert, N.; Girard, J. L.

    2003-08-01

    We present a customized 64-channel ASIC, named ALIX, developed in a 0.8 μm CMOS technology. This circuit is dedicated to measure charges from semi-conductor X-ray detectors like Cadmium Zinc Telluride (CZT) or Cadmium Telluride CdTe. The specificity of ALIX is to be able to measure charges over a very large dynamic range (from 10 fC to 3 nC), and to store eight measurements in a very short time (from every 250 ns to a few ms). Up to eight images are stored inside the ASIC and each image can be read out in 64 μs. A new acquisition sequence can then be started. Two analog readouts are available, one for the X-ray signal and one for the offset and afterglow measurement in case of pulsed X-rays. The outputs are converted into digital values by two off-chip 14 bits Analog-to-Digital Converters (ADC). A first version of ALIX has been tested with CZT and CdTe detectors under high-energy pulsed X-ray photons (20 MeV, 60 ns pulses every 250 ns). We will present the different results of linearity and signal-to-noise ratio. A second version of ALIX has been designed with some corrections. Electrical tests performed on 85 ASICS showed that the corrections were successful. We are now able to integrate them behind a 64×32 pixels 1 mm pitch CZT detector. Such an ASIC could also be used for strip detectors where a large dynamic range and a fast response are necessary.

  5. Comparison of CdTe and CdZnTe Detectors for Field Determination of Uranium Isotopic Enrichments

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, KJ

    2004-01-23

    A performance comparison of a CdTe and a CdZnTe detector when exposed to uranium samples of various isotopic enrichments has been performed. These high-resolution detectors can assist in the rapid determination of uranium isotopic content of illicit material. Spectra were recorded from these room temperature semiconductor detectors with a portable multi-channel analyzer, both in the laboratory and in a field environment. Both detectors were operated below ambient temperature using the vendor supplied thermoelectric coolers. Both detectors had nominally the same active volume (18 mm3 for the CdZnTe and 25 mm3 for the CdTe detector) and resolution. Spectra of samples of known isotopic content were recorded at fixed geometries. An evaluation of potential signature g rays for the detection of enriched uranium was completed. Operational advantages and disadvantages of each detector are discussed. There is a need to improve the detection sensitivity during the interdiction of special nuclear materials (SNM) for increased homeland protection. It is essential to provide additional tools to first responders and law enforcement personnel for assessing nuclear and radiological threats.

  6. Wafer-fused semiconductor radiation detector

    Science.gov (United States)

    Lee, Edwin Y.; James, Ralph B.

    2002-01-01

    Wafer-fused semiconductor radiation detector useful for gamma-ray and x-ray spectrometers and imaging systems. The detector is fabricated using wafer fusion to insert an electrically conductive grid, typically comprising a metal, between two solid semiconductor pieces, one having a cathode (negative electrode) and the other having an anode (positive electrode). The wafer fused semiconductor radiation detector functions like the commonly used Frisch grid radiation detector, in which an electrically conductive grid is inserted in high vacuum between the cathode and the anode. The wafer-fused semiconductor radiation detector can be fabricated using the same or two different semiconductor materials of different sizes and of the same or different thicknesses; and it may utilize a wide range of metals, or other electrically conducting materials, to form the grid, to optimize the detector performance, without being constrained by structural dissimilarity of the individual parts. The wafer-fused detector is basically formed, for example, by etching spaced grooves across one end of one of two pieces of semiconductor materials, partially filling the grooves with a selected electrical conductor which forms a grid electrode, and then fusing the grooved end of the one semiconductor piece to an end of the other semiconductor piece with a cathode and an anode being formed on opposite ends of the semiconductor pieces.

  7. Semiconductor High-Energy Radiation Scintillation Detector

    CERN Document Server

    Kastalsky, A; Spivak, B

    2006-01-01

    We propose a new scintillation-type detector in which high-energy radiation produces electron-hole pairs in a direct-gap semiconductor material that subsequently recombine producing infrared light to be registered by a photo-detector. The key issue is how to make the semiconductor essentially transparent to its own infrared light, so that photons generated deep inside the semiconductor could reach its surface without tangible attenuation. We discuss two ways to accomplish this, one based on doping the semiconductor with shallow impurities of one polarity type, preferably donors, the other by heterostructure bandgap engineering. The proposed semiconductor scintillator combines the best properties of currently existing radiation detectors and can be used for both simple radiation monitoring, like a Geiger counter, and for high-resolution spectrography of the high-energy radiation. The most important advantage of the proposed detector is its fast response time, about 1 ns, essentially limited only by the recombi...

  8. An NMR quantum computer of the semiconductor CdTe

    Science.gov (United States)

    Shimizu, T.; Goto, A.; Hashi, K.; Ohki, S.

    2002-12-01

    We propose a method to implement a quantum computer by solid-state NMR. We can use the J-coupling for the quantum gate in CdTe. Both Cd and Te have two isotopes with spin 1/2, then we can have 4-qubits. The decoherence by dipole interaction may be minimized by preparing the isotope superlattice grown in the order of— 111Cd- 123Te- 113Cd- 125Te—in the [111] direction and by applying the magnetic field in the direction of [100], the magic angle of the dipole interaction. The optical pumping technique can be used in CdTe to make the initialization of the qubits.

  9. A pixellated γ-camera based on CdTe detectors clinical interests and performances

    Science.gov (United States)

    Chambron, J.; Arntz, Y.; Eclancher, B.; Scheiber, Ch; Siffert, P.; Hage Hali, M.; Regal, R.; Kazandjian, A.; Prat, V.; Thomas, S.; Warren, S.; Matz, R.; Jahnke, A.; Karman, M.; Pszota, A.; Nemeth, L.

    2000-07-01

    A mobile gamma camera dedicated to nuclear cardiology, based on a 15 cm×15 cm detection matrix of 2304 CdTe detector elements, 2.83 mm×2.83 mm×2 mm, has been developed with a European Community support to academic and industrial research centres. The intrinsic properties of the semiconductor crystals - low-ionisation energy, high-energy resolution, high attenuation coefficient - are potentially attractive to improve the γ-camera performances. But their use as γ detectors for medical imaging at high resolution requires production of high-grade materials and large quantities of sophisticated read-out electronics. The decision was taken to use CdTe rather than CdZnTe, because the manufacturer (Eurorad, France) has a large experience for producing high-grade materials, with a good homogeneity and stability and whose transport properties, characterised by the mobility-lifetime product, are at least 5 times greater than that of CdZnTe. The detector matrix is divided in 9 square units, each unit is composed of 256 detectors shared in 16 modules. Each module consists in a thin ceramic plate holding a line of 16 detectors, in four groups of four for an easy replacement, and holding a special 16 channels integrated circuit designed by CLRC (UK). A detection and acquisition logic based on a DSP card and a PC has been programmed by Eurorad for spectral and counting acquisition modes. Collimators LEAP and LEHR from commercial design, mobile gantry and clinical software were provided by Siemens (Germany). The γ-camera head housing, its general mounting and the electric connections were performed by Phase Laboratory (CNRS, France). The compactness of the γ-camera head, thin detectors matrix, electronic readout and collimator, facilitates the detection of close γ sources with the advantage of a high spatial resolution. Such an equipment is intended to bedside explorations. There is a growing clinical requirement in nuclear cardiology to early assess the extent of an

  10. Fine-pitch CdTe detector for hard X-ray imaging and spectroscopy of the Sun with the FOXSI rocket experiment

    Science.gov (United States)

    Ishikawa, Shin-nosuke; Katsuragawa, Miho; Watanabe, Shin; Uchida, Yuusuke; Takeda, Shin'ichiro; Takahashi, Tadayuki; Saito, Shinya; Glesener, Lindsay; Buitrago-Casas, Juan Camilo; Krucker, Säm.; Christe, Steven

    2016-07-01

    We have developed a fine-pitch hard X-ray (HXR) detector using a cadmium telluride (CdTe) semiconductor for imaging and spectroscopy for the second launch of the Focusing Optics Solar X-ray Imager (FOXSI). FOXSI is a rocket experiment to perform high sensitivity HXR observations from 4 to 15 keV using the new technique of HXR focusing optics. The focal plane detector requires -30°C). Double-sided silicon strip detectors were used for the first FOXSI flight in 2012 to meet these criteria. To improve the detectors' efficiency (66% at 15 keV for the silicon detectors) and position resolution of 75 μm for the second launch, we fabricated double-sided CdTe strip detectors with a position resolution of 60 μm and almost 100% efficiency for the FOXSI energy range. The sensitive area is 7.67 mm × 7.67 mm, corresponding to the field of view of 791'' × 791''. An energy resolution of 1 keV (FWHM) and low-energy threshold of ≈4 keV were achieved in laboratory calibrations. The second launch of FOXSI was performed on 11 December 2014, and images from the Sun were successfully obtained with the CdTe detector. Therefore, we successfully demonstrated the detector concept and the usefulness of this technique for future HXR observations of the Sun.

  11. Estimation of mammary gland composition using CdTe series detector developed for photon-counting mammography

    Science.gov (United States)

    Ihori, Akiko; Okamoto, Chizuru; Yamakawa, Tsutomu; Yamamoto, Shuichiro; Okada, Masahiro; Nakajima, Ai; Kato, Misa; Kodera, Yoshie

    2016-03-01

    Energy resolved photon-counting mammography is a new technology, which counts the number of photons that passes through an object, and presents it as a pixel value in an image of the object. Silicon semiconductor detectors are currently used in commercial mammography. However, the disadvantage of silicon is the low absorption efficiency for high X-ray energies. A cadmium telluride (CdTe) series detector has a high absorption efficiency over a wide energy range. In this study, we proposed a method to estimate the composition of the mammary gland using a CdTe series detector as a photon-counting detector. The fact that the detection rate of breast cancer in mammography is affected by mammary gland composition is now widely accepted. Assessment of composition of the mammary gland has important implications. An important advantage of our proposed technique is its ability to discriminate photons using three energy bins. We designed the CdTe series detector system using the MATLAB simulation software. The phantom contains nine regions with the ratio of glandular tissue and adipose varying in increments of 10%. The attenuation coefficient for each bin's energy was calculated from the number of input and output photons possessed by each. The evaluation results obtained by plotting the attenuation coefficient μ in a three-dimensional (3D) scatter plot show that the plots had a regular composition order congruent with that of the mammary gland. Consequently, we believe that our proposed method can be used to estimate the composition of the mammary gland.

  12. CdTe detector based PIXE mapping of geological samples

    Energy Technology Data Exchange (ETDEWEB)

    Chaves, P.C., E-mail: cchaves@ctn.ist.utl.pt [Centro de Física Atómica da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Campus Tecnológico e Nuclear, EN10, 2686-953 Sacavém (Portugal); Taborda, A. [Centro de Física Atómica da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Campus Tecnológico e Nuclear, EN10, 2686-953 Sacavém (Portugal); Oliveira, D.P.S. de [Laboratório Nacional de Energia e Geologia (LNEG), Apartado 7586, 2611-901 Alfragide (Portugal); Reis, M.A. [Centro de Física Atómica da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Campus Tecnológico e Nuclear, EN10, 2686-953 Sacavém (Portugal)

    2014-01-01

    A sample collected from a borehole drilled approximately 10 km ESE of Bragança, Trás-os-Montes, was analysed by standard and high energy PIXE at both CTN (previous ITN) PIXE setups. The sample is a fine-grained metapyroxenite grading to coarse-grained in the base with disseminated sulphides and fine veinlets of pyrrhotite and pyrite. Matrix composition was obtained at the standard PIXE setup using a 1.25 MeV H{sup +} beam at three different spots. Medium and high Z elemental concentrations were then determined using the DT2fit and DT2simul codes (Reis et al., 2008, 2013 [1,2]), on the spectra obtained in the High Resolution and High Energy (HRHE)-PIXE setup (Chaves et al., 2013 [3]) by irradiation of the sample with a 3.8 MeV proton beam provided by the CTN 3 MV Tandetron accelerator. In this paper we present results, discuss detection limits of the method and the added value of the use of the CdTe detector in this context.

  13. Characterization and simulation of a CdTe detector for use in PET

    OpenAIRE

    Ariño Estrada, Gerard; Chmeissani, Mokhtar; Lorenzo, Gianluca De

    2012-01-01

    The Voxel Imaging PET (VIP) Path nder project got the 4 year European Research Council FP7 grant in 2010 to prove the feasibility of using CdTe detectors in a novel conceptual design of PET scanner. The work presented in this thesis is a part of the VIP project and consists of, on the one hand, the characterization of a CdTe detector in terms of energy resolution and coincidence time resolution and, on the other hand, the simulation of the setup with the single detector in order to extend the...

  14. Evaluation of Compton gamma camera prototype based on pixelated CdTe detectors

    OpenAIRE

    Y Calderón; Chmeissani, M.; Kolstein, M.; De Lorenzo, G.

    2014-01-01

    A proposed Compton camera prototype based on pixelated CdTe is simulated and evaluated in order to establish its feasibility and expected performance in real laboratory tests. The system is based on module units containing a 2×4 array of square CdTe detectors of 10×10 mm2 area and 2 mm thickness. The detectors are pixelated and stacked forming a 3D detector with voxel sizes of 2 × 1 × 2 mm3. The camera performance is simulated with Geant4-based Architecture for Medicine-Oriented Simulations(G...

  15. High performance p-i-n CdTe and CdZnTe detectors

    CERN Document Server

    Khusainov, A K; Ilves, A G; Morozov, V F; Pustovoit, A K; Arlt, R D

    1999-01-01

    A breakthrough in the performance of p-i-n CdTe and CdZnTe detectors is reported. The detector stability has been significantly improved, allowing their use in precise gamma and XRF applications. Detectors with energy resolution close to Si and Ge were produced operating with only -30--35 deg. C cooling (by a Peltier cooler of 15x15x10 mm size and a consumed power less than 5 W). Presently detectors with volume of up to 300 mm sup 3 are available. In terms of photoelectric effect efficiency it corresponds to HPGe detectors with volumes of about 1.5 cm sup 3. The possibilities of further improvement of CdTe and CdZnTe detector characteristics are discussed in this paper.

  16. Imaging performance comparison between a LaBr3: Ce scintillator based and a CdTe semiconductor based photon counting compact gamma camera.

    Science.gov (United States)

    Russo, P; Mettivier, G; Pani, R; Pellegrini, R; Cinti, M N; Bennati, P

    2009-04-01

    The authors report on the performance of two small field of view, compact gamma cameras working in single photon counting in planar imaging tests at 122 and 140 keV. The first camera is based on a LaBr3: Ce scintillator continuous crystal (49 x 49 x 5 mm3) assembled with a flat panel multianode photomultiplier tube with parallel readout. The second one belongs to the class of semiconductor hybrid pixel detectors, specifically, a CdTe pixel detector (14 x 14 x 1 mm3) with 256 x 256 square pixels and a pitch of 55 microm, read out by a CMOS single photon counting integrated circuit of the Medipix2 series. The scintillation camera was operated with selectable energy window while the CdTe camera was operated with a single low-energy detection threshold of about 20 keV, i.e., without energy discrimination. The detectors were coupled to pinhole or parallel-hole high-resolution collimators. The evaluation of their overall performance in basic imaging tasks is presented through measurements of their detection efficiency, intrinsic spatial resolution, noise, image SNR, and contrast recovery. The scintillation and CdTe cameras showed, respectively, detection efficiencies at 122 keV of 83% and 45%, intrinsic spatial resolutions of 0.9 mm and 75 microm, and total background noises of 40.5 and 1.6 cps. Imaging tests with high-resolution parallel-hole and pinhole collimators are also reported.

  17. Semiconductor nanowires self-assembled from colloidal CdTe nanocrystal building blocks: optical properties and application perspectives

    OpenAIRE

    RAKOVICH, YURY; DONEGAN, JOHN FRANCIS

    2012-01-01

    PUBLISHED Solution-based self-assembly of quasi-one-dimensional semiconductor nanostructures (nanowires) from quasi-zero-dimensional (quantum dots) colloidal nanocrystal building blocks has proven itself as a powerful and flexible preparation technique. Polycrystalline CdTe nanowires self-assembled from light-emitting thiol-capped CdTe nanocrystals are the focus of this Feature Article. These nanowires represent an interesting model system for quantum dot solids, where electronic coupling ...

  18. Semiconductor nanowires self-assembled from colloidal CdTe nanocrystal building blocks: optical properties and application perspectives

    OpenAIRE

    Rakovich, Yury P.; Jäckel, Frank; Donegan, John F.; Rogach, Andrey L

    2012-01-01

    Solution-based self-assembly of quasi-one-dimensional semiconductor nanostructures (nanowires) from quasi-zero-dimensional (quantum dots) colloidal nanocrystal building blocks has proven itself as a powerful and flexible preparation technique. Polycrystalline CdTe nanowires self-assembled from light-emitting thiol-capped CdTe nanocrystals are the focus of this Feature Article. These nanowires represent an interesting model system for quantum dot solids, where electronic coupling between the i...

  19. Simulation of active-edge pixelated CdTe radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, D.D., E-mail: diana.duarte@stfc.ac.uk [STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Lipp, J.D.; Schneider, A.; Seller, P.; Veale, M.C.; Wilson, M.D. [STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Baker, M.A.; Sellin, P.J. [Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

    2016-01-11

    The edge surfaces of single crystal CdTe play an important role in the electronic properties and performance of this material as an X-ray and γ-ray radiation detector. Edge effects have previously been reported to reduce the spectroscopic performance of the edge pixels in pixelated CdTe radiation detectors without guard bands. A novel Technology Computer Aided Design (TCAD) model based on experimental data has been developed to investigate these effects. The results presented in this paper show how localized low resistivity surfaces modify the internal electric field of CdTe creating potential wells. These result in a reduction of charge collection efficiency of the edge pixels, which compares well with experimental data.

  20. New materials for radiation hard semiconductor detectors

    CERN Document Server

    Sellin, P J; CERN. Geneva

    2006-01-01

    We present a review of the current status of research into new semiconductor materials for use as particle tracking detectors in very high radiation environments. This work is carried out within the framework of the CERN RD50 collaboration, which is investigating detector technologies suitable for operation at the proposed Super-LHC facility (SLHC). Tracking detectors operating at the SLHC in this environment will have to be capable of withstanding radiation levels arising from a luminosity of 1035 cm-2s-1 which will present severe challenges to current tracking detector technologies. The "new materials" activity within RD50 is investigating the performance of various semiconductor materials that potentially offer radiation hard alternatives to silicon devices. The main contenders in this study are silicon carbide, gallium nitride and amorphous silicon. In this paper we review the current status of these materials, in terms of material quality, commercial availability, charge transport properties, and radiati...

  1. Studies of crystalline CdZnTe radiation detectors and polycrystalline thin film CdTe for X-ray imaging applications

    CERN Document Server

    Ede, A

    2001-01-01

    The development of a replacement to the conventional film based X-ray imaging technique is required for many reasons. One possible route for this is the use of a large area film of a suitable semiconductor overlaid on an amorphous silicon readout array. A suitable semiconductor exists in cadmium telluride and its tertiary alloy cadmium zinc telluride. In this thesis the spectroscopic characteristics of commercially available CZT X- and gamma-radiation detectors are established. The electronic, optical, electro-optic, structural and compositional properties of these detectors are then investigated. The attained data is used to infer a greater understanding for the carrier transport in a CZT radiation detector following the interaction of a high energy photon. Following this a method used to fabricate large area films of CdTe on a commercial scale is described. This is cathodic electrodeposition from an aqueous electrolyte. The theory and experimental arrangement for this technique are described in detail with ...

  2. A facile and green preparation of high-quality CdTe semiconductor nanocrystals at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yan [Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Changchun 130023 (China); Shen Qihui; Shi Weiguang; Li Jixue; Liu Xiaoyang [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Yu Dongdong [1st Hopstail affiliated to Jilin University, Jilin University, Changchun 130023 (China); Zhou Jianguang [Research Center for Analytical Instrumentation, Zhejiang University, Hangzhou 310058 (China)], E-mail: liuxy@jlu.edu.cn, E-mail: jgzhou70@126.com

    2008-06-18

    One chemical reagent, hydrazine hydrate, was discovered to accelerate the growth of semiconductor nanocrystals (cadmium telluride) instead of additional energy, which was applied to the synthesis of high-quality CdTe nanocrystals at room temperature and ambient conditions within several hours. Under this mild condition the mercapto stabilizers were not destroyed, and they guaranteed CdTe nanocrystal particle sizes with narrow and uniform distribution over the largest possible range. The CdTe nanocrystals (photoluminescence emission range of 530-660 nm) synthesized in this way had very good spectral properties; for instance, they showed high photoluminescence quantum yield of up to 60%. Furthermore, we have succeeded in detecting the living Borrelia burgdorferi of Lyme disease by its photoluminescence image using CdTe nanocrystals.

  3. Semiconductor detectors in the low countries

    CERN Document Server

    Heijne, Erik H M

    2003-01-01

    Several milestones in the development of semiconductor radiation imaging detectors are attributed to scientists from the Low Countries, the Netherlands and Belgium, and a few historical details will be highlighted. The very first usable semiconductor nuclear detector was made in Utrecht, around 1943, in the form of an AgCl crystal. The earliest large-scale application of monolithic, double- sided silicon strip detectors was in the BOL experiment around 1968 at IKO, now NIKHEF, in Amsterdam. The technology developed and patented by Philips and IKO was adapted by the author and coworkers in 1980 to produce the first silicon microstrip detector used for the reconstruction of events in a CERN fixed target experiment. An avalanche of developments then led to worldwide use of silicon microstrip detectors in elementary particle physics, motivated by the capability to reconstruct particles with lifetime similar to 10**- **1**2s, which decay on sub-millimeter scale. The intensive activity in silicon detector R&D c...

  4. An investigation of performance characteristics of a pixellated room-temperature semiconductor detector for medical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, P; Santos, A [Centro de Investigacion Biomedica de Bioningenieria, Biomateriales y Nanomedicina, CEEI-Modulo 3, C/ Maria de Luna, 11, 50018 Zaragoza (United States); Darambara, D G, E-mail: pguerra@ciber-bbn.e [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Fulham Road, London SW3 6JJ (United Kingdom)

    2009-09-07

    The operation of any semiconductor detector depends on the movement of the charge carriers, which are created within the material when radiation passes through, as a result of energy deposition. The carrier movement in the bulk semiconductor induces charges on the metal electrodes, and therefore a current on the electrodes and the external circuit. The induced charge strongly depends on the material transport parameters as well as the geometrical dimensions of a pixellated semiconductor detector. This work focuses on the performance optimization in terms of energy resolution, detection efficiency and intrinsic spatial resolution of a room-temperature semiconductor pixellated detector based on CdTe/CdZnTe. It analyses and inter-relates these performance figures for various dimensions of CdTe and CdZnTe detectors and for an energy range spanning from x-ray (25 keV) to PET (511 keV) imaging. Monte Carlo simulations, which integrate a detailed and accurate noise model, are carried out to investigate several CdTe/CdZnTe configurations and to determine possible design specifications. Under the considered conditions, the simulations demonstrate the superiority of the CdZnTe over the CdTe in terms of energy resolution and sensitivity in the photopeak. Further, according to the results, the spatial resolution is maximized at high energies and the energy resolution at low energies, while a reasonable detection efficiency is achieved at high energies, with a 1 x 1 x 6 mm{sup 3} CdZnTe pixellated detector.

  5. Development of Large Cryogenic Semiconductor Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Mandic, Vuk [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-12-09

    This project aims at developing large cryogenic semiconductor detectors for applications in particle physics and more broadly. We have developed a 150 mm diameter, 43 mm thick, Si-based detector that measures ionization released in an interaction of a particle inside the silicon crystal of high purity, operated at 30 mK temperature. We demonstrated that such a detector can be used to measure recoil energies on the keV scale, and that its stable operation can be maintained indefinitely. Detectors of this type could therefore be used in the fields of direct dark matter searches, coherent neutrino scattering measurements, X-ray observations, as well as in broader applications such as homeland security.

  6. Characterization of a pixelated CdTe Timepix detector operated in ToT mode

    Science.gov (United States)

    Billoud, T.; Leroy, C.; Papadatos, C.; Pichotka, M.; Pospisil, S.; Roux, J. S.

    2017-01-01

    A 1 mm thick CdTe sensor bump-bonded to a Timepix readout chip operating in Time-over-Threshold (ToT) mode has been characterized in view of possible applications in particle and medical physics. The CdTe sensor layer was segmented into 256 × 256 pixels, with a pixel pitch of 55 μm. This CdTe Timepix device, of ohmic contact type, has been exposed to alpha-particles and photons from an 241Am source, photons from a 137Cs source, and protons of different energies (0.8–10 MeV) delivered by the University of Montreal Tandem Accelerator. The device was irradiated on the negatively biased backside electrode. An X-ray per-pixel calibration commonly used for this type of detector was done and its accuracy and resolution were assessed and compared to those of a 300 μm thick silicon Timepix device. The electron mobility-lifetime product (μeτe) of CdTe for protons of low energy has been obtained from the Hecht equation. Possible polarization effects have been also investigated. Finally, information about the homogeneity of the detector was obtained from X-ray irradiation.

  7. Fine-pitch CdTe detector for hard X-ray imaging and spectroscopy of the Sun with the FOXSI rocket experiment

    CERN Document Server

    Ishikawa, S; Watanabe, S; Uchida, Y; Takeda, S; Takahashi, T; Saito, S; Glesener, L; Buitrago-Casas, J C; Krucker, S; Christe, S

    2016-01-01

    We have developed a fine-pitch hard X-ray (HXR) detector using a cadmium telluride (CdTe) semiconductor for imaging and spectroscopy for the second launch of the Focusing Optics Solar X-ray Imager (FOXSI). FOXSI is a rocket experiment to perform high sensitivity HXR observations from 4-15 keV using the new technique of HXR focusing optics. The focal plane detector requires -30 C). Double-sided silicon strip detectors were used for the first FOXSI flight in 2012 to meet these criteria. To improve the detectors' efficiency (66 at 15 keV for the silicon detectors) and position resolution of 75 um for the second launch, we fabricated double-sided CdTe strip detectors with a position resolution of 60 um and almost 100 % efficiency for the FOXSI energy range. The sensitive area is 7.67 mm x 7.67 mm, corresponding to the field of view of 791'' x 791''. An energy resolution of about 1 keV (FWHM) and low energy threshold of 4 keV were achieved in laboratory calibrations. The second launch of FOXSI was performed on De...

  8. Fast polycrystalline CdTe detectors for bunch-by-bunch luminosity monitoring in the LHC

    CERN Document Server

    Brambilla, A; Jolliot, M; Bravin, E

    2008-01-01

    The luminosity at the four interaction points of the Large Hadron Collider (LHC) must be continuously monitored in order to provide an adequate tool for the control and optimisation of beam parameters. Polycrystalline cadmium telluride (CdTe) detectors have previously been tested, showing their high potential to fulfil the requirements of luminosity measurement in the severe environment of the LHC interaction regions. Further, the large signal yield and the fast response time should allow bunch-by-bunch measurement of the luminosity at 40 MHz with high accuracy. Four luminosity monitors with two rows of five polycrystalline CdTe detectors each have been fabricated and will be installed at both sides of the low-luminosity interaction points ALICE and LHC-b. A detector housing was specially designed to meet the mechanical constraints in the LHC. A series of elementary CdTe detectors were fabricated and tested, of which 40 were selected for the luminosity monitors. A sensitivity of 104 electrons per minimum ioni...

  9. Improvement of the sensitivity of CdTe detectors in the high energy regions

    Energy Technology Data Exchange (ETDEWEB)

    Nishizawa, Hiroshi; Ikegami, Kazunori; Takashima, Kazuo; Usami, Teruo [Mitsubishi Electric Corp., Tokyo (Japan); Yamamoto, Takayoshi

    1996-07-01

    In order to improve the efficiency of the full energy peak in the high energy regions, we had previously suggested a multi-layered structure of CdTe elements and have since confirmed the sensitivity improvement of the full energy peak. And furthermore, we have suggested a new type structure of multi-layered elements in this paper and we confirmed that the efficiency of the full energy peak became higher and that more proper energy spectra were obtained by our current experiment than by the detector with the conventional structure. This paper describes a simulation and experiment to improve the efficiency of the full energy peak and to obtain the more proper energy spectra of {sup 137}Cs (662keV) and {sup 60}Co (1.17 and 1.33MeV) using the new structure of CdTe detector. (J.P.N.)

  10. Energy and coincidence time resolution measurements of CdTe detectors for PET

    Science.gov (United States)

    Ariño, G.; Chmeissani, M.; De Lorenzo, G.; Puigdengoles, C.; Cabruja, E.; Calderón, Y.; Kolstein, M.; Macias-Montero, J. G.; Martinez, R.; Mikhaylova, E.; Uzun, D.

    2013-02-01

    We report on the characterization of 2 mm thick CdTe diode detector with Schottky contacts to be employed in a novel conceptual design of PET scanner. Results at -8°C with an applied bias voltage of -1000 V/mm show a 1.2% FWHM energy resolution at 511 keV. Coincidence time resolution has been measured by triggering on the preamplifier output signal to improve the timing resolution of the detector. Results at the same bias and temperature conditions show a FWHM of 6 ns with a minimum acceptance energy of 500 keV. These results show that pixelated CdTe Schottky diode is an excellent candidate for the development of next generation nuclear medical imaging devices such as PET, Compton gamma cameras, and especially PET-MRI hybrid systems when used in a magnetic field immune configuration.

  11. Correction of diagnostic x-ray spectra measured with CdTe and CdZnTe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, M. [Osaka Univ., Suita (Japan). Medical School; Kanamori, H.; Toragaito, T.; Taniguchi, A.

    1996-07-01

    We modified the formula of stripping procedure presented by E. Di. Castor et al. We added the Compton scattering and separated K{sub {alpha}} radiation of Cd and Te (23 and 27keV, respectively). Using the new stripping procedure diagnostic x-ray spectra (object 4mm-Al) of tube voltage 50kV to 100kV for CdTe and CdZnTe detectors are corrected with comparison of those spectra for the Ge detector. The corrected spectra for CdTe and CdZnTe detectors coincide with those for Ge detector at lower tube voltage than 70kV. But the corrected spectra at higher tube voltage than 70kV do not coincide with those for Ge detector. The reason is incomplete correction for full energy peak efficiencies of real CdTe and CdZnTe detectors. (J.P.N.)

  12. Imaging detector development for nuclear astrophysics using pixelated CdTe

    Science.gov (United States)

    Álvarez, J. M.; Gálvez, J. L.; Hernanz, M.; Isern, J.; Llopis, M.; Lozano, M.; Pellegrini, G.; Chmeissani, M.

    2010-11-01

    The concept of focusing telescopes in the energy range of lines of astrophysical interest (i.e., of energies around 1 MeV) should allow to reach unprecedented sensitivities, essential to perform detailed studies of cosmic explosions and cosmic accelerators. Our research and development activities aim to study a detector suited for the focal plane of a γ-ray telescope mission. A CdTe/CdZnTe detector operating at room temperature, that combines high detection efficiency with good spatial and spectral resolution is being studied in recent years as a focal plane detector, with the interesting option of also operating as a Compton telescope monitor. We present the current status of the design and development of a γ-ray imaging spectrometer in the MeV range, for nuclear astrophysics, consisting of a stack of CdTe pixel detectors with increasing thicknesses. We have developed an initial prototype based on CdTe ohmic detector. The detector has 11×11 pixels, with a pixel pitch of 1 mm and a thickness of 2 mm. Each pixel is stud bonded to a fanout board and routed to an front end ASIC to measure pulse height and rise time information for each incident γ-ray photon. First measurements of a 133Ba and 241Am source are reported here.

  13. Imaging detector development for nuclear astrophysics using pixelated CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, J.M., E-mail: alvarez@ieec.uab.e [Institut de Ciencies de l' Espai (CSIC-IEEC), Campus UAB, E-08193 Barcelona (Spain); Galvez, J.L.; Hernanz, M.; Isern, J.; Llopis, M. [Institut de Ciencies de l' Espai (CSIC-IEEC), Campus UAB, E-08193 Barcelona (Spain); Lozano, M.; Pellegrini, G. [Centro Nacional de Microelectronica - IMB-CNM (CSIC), Campus UAB, E-08193 Barcelona (Spain); Chmeissani, M. [Institut de Fisica d' Altes Energies (IFAE), Campus UAB, E-08193 Barcelona (Spain)

    2010-11-01

    The concept of focusing telescopes in the energy range of lines of astrophysical interest (i.e., of energies around 1 MeV) should allow to reach unprecedented sensitivities, essential to perform detailed studies of cosmic explosions and cosmic accelerators. Our research and development activities aim to study a detector suited for the focal plane of a {gamma}-ray telescope mission. A CdTe/CdZnTe detector operating at room temperature, that combines high detection efficiency with good spatial and spectral resolution is being studied in recent years as a focal plane detector, with the interesting option of also operating as a Compton telescope monitor. We present the current status of the design and development of a {gamma}-ray imaging spectrometer in the MeV range, for nuclear astrophysics, consisting of a stack of CdTe pixel detectors with increasing thicknesses. We have developed an initial prototype based on CdTe ohmic detector. The detector has 11x11 pixels, with a pixel pitch of 1 mm and a thickness of 2 mm. Each pixel is stud bonded to a fanout board and routed to an front end ASIC to measure pulse height and rise time information for each incident {gamma}-ray photon. First measurements of a {sup 133}Ba and {sup 241}Am source are reported here.

  14. Electronic Band Structure and New Magneto-transport Properties in p-type Semiconductor Medium-infrared HgTe / CdTe Superlattice

    Science.gov (United States)

    Nafidi, Ab.; EL Abidi, A.; El Kaaouachi, A.; Nafidi, Ah.

    2005-06-01

    We report here the band structure and new magneto-transport results for HgTe (56 Å) / CdTe (30 Å) superlattice grown by molecular beam epitaxy (MBE). The angular dependence of the transverse magnetoresistance follows the two-dimensional (2D) behaviour. At low temperature, the sample exhibits p type conductivity with a concentration of 1.84×1012 cm-2 and a Hall mobility of 8200 cm2/Vs. The observed Shubnikov-de Haas effect gives a carrier density of 1.80×1012 cm-2. The superlattice heavy holes dominate the conduction in plane with an effective mass of 0.297 m0 and Fermi energy (2D) of 14 meV. In intrinsic regime, the measured gap Eg = 190 meV agree well with calculated Eg(Γ, 300 K) =178 meV. The formalism used here predicts that the system is semiconductor, for our HgTe to CdTe thickness ratio d1/d2 = 1,87, when d2 < 140 Å. In our case, d2=30 Å and Eg (Γ, 4.2 K) = 111 meV. In spite of it, the sample exhibits the features typical of a p type semiconductor and is a medium-infrared detector (7 μm< λ< 11 μm).

  15. X-ray micro-beam characterization of a small pixel spectroscopic CdTe detector

    Science.gov (United States)

    Veale, M. C.; Bell, S. J.; Seller, P.; Wilson, M. D.; Kachkanov, V.

    2012-07-01

    A small pixel, spectroscopic, CdTe detector has been developed at the Rutherford Appleton Laboratory (RAL) for X-ray imaging applications. The detector consists of 80 × 80 pixels on a 250 μm pitch with 50 μm inter-pixel spacing. Measurements with an 241Am γ-source demonstrated that 96% of all pixels have a FWHM of better than 1 keV while the majority of the remaining pixels have FWHM of less than 4 keV. Using the Diamond Light Source synchrotron, a 10 μm collimated beam of monochromatic 20 keV X-rays has been used to map the spatial variation in the detector response and the effects of charge sharing corrections on detector efficiency and resolution. The mapping measurements revealed the presence of inclusions in the detector and quantified their effect on the spectroscopic resolution of pixels.

  16. Recent advances in Tl Br, Cd Te and CdZnTe semiconductor radiation detectors: a review

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Icimone B. [Universidade Bandeirante (UNIBAN), Sao Paulo, SP (Brazil)

    2011-07-01

    The success in the development of radiation spectrometers operating at room temperature is based on many years of effort on the part of large numbers of workers around the world. These individuals have contributed to the understanding of the fundamental materials issues associated with the growth of semiconductors for this application, the development of device fabrication and processing technology, and advances in low noise electronics and pulse processing. Progress in this field continues at an accelerated pace, as in evidenced by the improvements in detector performance and by the growing number of commercial products. Thus, the last years have been seen continued effort in the development of room temperature compound semiconductors devices. High-Z compound semiconductor detectors has been explored for high energy resolution, high detection efficiency and are of low cost. Compound semiconductors detectors are well suited for addressing needs of demanding applications such as bore hole logging where high operating temperature are encountered. In this work recent developments in semiconductors detectors were reviewed. This review concentrated on thallium bromide (TlBr), cadmium zinc telluride (CdZnTe) and cadmium telluride (CdTe) crystals detectors. TlBr has higher stopping power compared to common semiconductor materials because it has the higher photoelectric and total attenuation coefficients over wide energy range from 100 keV to 1 MeV. CdTe and CdZnTe detectors have several attractive features for detecting X-ray and low energy gamma ray. Their relatively large band gaps lead to a relatively low leakage current and offer an excellent energy resolution at room temperature. A literature survey and bibliography was also included. (author)

  17. ASTRO-H CdTe detectors proton irradiation at PIF

    Energy Technology Data Exchange (ETDEWEB)

    Limousin, O.; Renaud, D.; Horeau, B.; Dubos, S. [CEA-Irfu – CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France); Laurent, P.; Lebrun, F. [APC Laboratory, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France); Chipaux, R. [CEA-Irfu – CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France); Boatella Polo, C. [European Space Agency, ESTEC, Keplerlaan 1, NL-2201 AZ, Noordwijk (Netherlands); Marcinkowski, R. [Paul Scherrer Institute (PSI), Proton Irradiation Facility at Laboratory for Particle Physics, 5232 Villigen (Switzerland); Kawaharada, M.; Watanabe, S.; Ohta, M.; Sato, G.; Takahashi, T. [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa, 252-5210 (Japan)

    2015-07-01

    Asbstract: The French Atomic Energy Commission (CEA), with the support of the European Space Agency (ESA), is partner of the Soft Gamma-Ray Detector (SGD) and the Hard X-ray Imager (HXI) onboard the 6th Japanese X-ray scientific satellite ASTRO-H (JAXA) initiated by the Institute of Space and Astronautical Science (ISAS). Both scientific instruments, one hosting a series of Compton Gamma Cameras and the other being a focal plane of a grazing incidence mirror telescope in the hard X-ray domain, are equipped with Cadmium Telluride based detectors. ASTRO-H will be operated in a Low Earth Orbit with a 31° inclination at ~550 km altitude, thus passing daily through the South Atlantic Anomaly radiation belt, a specially harsh environment where the detectors are suffering the effect of the interaction with trapped high energy protons. As CdTe detector performance might be affected by the irradiation, we investigate the effect of the accumulated proton fluence on their spectral response. To do so, we have characterized and irradiated representative samples of SGD and HXI detector under different conditions. The detectors in question, from ACRORAD, are single-pixels having a size of 2 mm by 2 mm and 750 µm thick. The Schottky contact is either made of an Indium or Aluminum for SGD and HXI respectively. We ran the irradiation test campaign at the Proton Irradiation Facility (PIF) at PSI, and ESA approved equipment to evaluate the radiation hardness of flight hardware. We simulated the proton flux expected on the sensors over the entire mission, and secondary neutrons flux due to primary proton interactions into the surrounding BGO active shielding. We eventually characterized the detector response evolution, emphasizing each detector spectral response as well as its stability by studying the so-called Polarization effect. The latter is provoking a spectral response degradation against time as a charge accumulation process occurs in Schottky type CdTe sensors. In this paper

  18. The Si/CdTe semiconductor Compton camera of the ASTRO-H Soft Gamma-ray Detector (SGD)

    CERN Document Server

    Watanabe, Shin; Fukazawa, Yasushi; Ichinohe, Yuto; Takeda, Shin'ichiro; Enoto, Teruaki; Fukuyama, Taro; Furui, Shunya; Genba, Kei; Hagino, Kouichi; Harayama, Astushi; Kuroda, Yoshikatsu; Matsuura, Daisuke; Nakamura, Ryo; Nakazawa, Kazuhiro; Noda, Hirofumi; Odaka, Hirokazu; Ohta, Masayuki; Onishi, Mitsunobu; Saito, Shinya; Sato, Goro; Sato, Tamotsu; Takahashi, Tadayuki; Tanaka, Takaaki; Togo, Atsushi; Tomizuka, Shinji

    2015-01-01

    The Soft Gamma-ray Detector (SGD) is one of the instrument payloads onboard ASTRO-H, and will cover a wide energy band (60--600 keV) at a background level 10 times better than instruments currently in orbit. The SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield. The Compton camera in the SGD is realized as a hybrid semiconductor detector system which consists of silicon and cadmium telluride (CdTe) sensors. The design of the SGD Compton camera has been finalized and the final prototype, which has the same configuration as the flight model, has been fabricated for performance evaluation. The Compton camera has overall dimensions of 12 cm x 12 cm x 12 cm, consisting of 32 layers of Si pixel sensors and 8 layers of CdTe pixel sensors surrounded by 2 layers of CdTe pixel sensors. The detection efficiency of the Compton camera reaches about 15% and 3% for 100 keV and 511 keV gamma rays, respectively. The pixel pitch of the Si and CdTe sensors is 3.2 mm, and ...

  19. Imaging and spectroscopic performance studies of pixellated CdTe Timepix detector

    Science.gov (United States)

    Maneuski, D.; Astromskas, V.; Fröjdh, E.; Fröjdh, C.; Gimenez, E. N.; Marchal, J.; O'Shea, V.; Stewart, G.; Tartoni, N.; Wilhelm, H.; Wraight, K.; Zain, R. M.

    2012-01-01

    In this work the results on imaging and spectroscopic performances of 14 × 14 × 1 mm CdTe detectors with 55 × 55 μm and 110 × 110 μm pixel pitch bump-bonded to a Timepix chip are presented. The performance of the 110 × 110 μm pixel detector was evaluated at the extreme conditions beam line I15 of the Diamond Light Source. The energy of X-rays was set between 25 and 77 keV. The beam was collimated through the edge slits to 20 μm FWHM incident in the middle of the pixel. The detector was operated in the time-over-threshold mode, allowing direct energy measurement. Energy in the neighbouring pixels was summed for spectra reconstruction. Energy resolution at 77 keV was found to be ΔE/E = 3.9%. Comparative imaging and energy resolution studies were carried out between two pixel size detectors with a fluorescence target X-ray tube and radioactive sources. The 110 × 110 μm pixel detector exhibited systematically better energy resolution in comparison to 55 × 55 μm. An imaging performance of 55 × 55 μm pixellated CdTe detector was assessed using the Modulation Transfer Function (MTF) technique and compared to the larger pixel. A considerable degradation in MTF was observed for bias voltages below -300 V. Significant room for improvement of the detector performance was identified both for imaging and spectroscopy and is discussed.

  20. Prompt gamma and neutron detection in BNCT utilizing a CdTe detector.

    Science.gov (United States)

    Winkler, Alexander; Koivunoro, Hanna; Reijonen, Vappu; Auterinen, Iiro; Savolainen, Sauli

    2015-12-01

    In this work, a novel sensor technology based on CdTe detectors was tested for prompt gamma and neutron detection using boronated targets in (epi)thermal neutron beam at FiR1 research reactor in Espoo, Finland. Dedicated neutron filter structures were omitted to enable simultaneous measurement of both gamma and neutron radiation at low reactor power (2.5 kW). Spectra were collected and analyzed in four different setups in order to study the feasibility of the detector to measure 478 keV prompt gamma photons released from the neutron capture reaction of boron-10. The detector proved to have the required sensitivity to detect and separate the signals from both boron neutron and cadmium neutron capture reactions, which makes it a promising candidate for monitoring the spatial and temporal development of in vivo boron distribution in boron neutron capture therapy.

  1. Evaluation of Compton gamma camera prototype based on pixelated CdTe detectors.

    Science.gov (United States)

    Calderón, Y; Chmeissani, M; Kolstein, M; De Lorenzo, G

    2014-06-01

    A proposed Compton camera prototype based on pixelated CdTe is simulated and evaluated in order to establish its feasibility and expected performance in real laboratory tests. The system is based on module units containing a 2×4 array of square CdTe detectors of 10×10 mm(2) area and 2 mm thickness. The detectors are pixelated and stacked forming a 3D detector with voxel sizes of 2 × 1 × 2 mm(3). The camera performance is simulated with Geant4-based Architecture for Medicine-Oriented Simulations(GAMOS) and the Origin Ensemble(OE) algorithm is used for the image reconstruction. The simulation shows that the camera can operate with up to 10(4) Bq source activities with equal efficiency and is completely saturated at 10(9) Bq. The efficiency of the system is evaluated using a simulated (18)F point source phantom in the center of the Field-of-View (FOV) achieving an intrinsic efficiency of 0.4 counts per second per kilobecquerel. The spatial resolution measured from the point spread function (PSF) shows a FWHM of 1.5 mm along the direction perpendicular to the scatterer, making it possible to distinguish two points at 3 mm separation with a peak-to-valley ratio of 8.

  2. About the use of photoacoustic spectroscopy for the optical characterization of semiconductor thin films: CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Marin, E.; Calderon, A. [CICATA-IPN, Av. Legaria 694, 11500 Mexico D.F. (Mexico); Vigil G, O.; Sastre, J.; Contreras P, G.; Aguilar H, J. [ESFM-IPN, 07738 Mexico D.F. (Mexico); Saucedo, E.; Ruiz, C.M. [Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain)

    2006-07-01

    CdTe has been used satisfactorily in multiple and diverse technological applications such as detectors of X and gamma rays that operate at room temperature, for digital imagenology of X rays with medical and industrial applications and as active part in CdTe/CdS solar cells. In form of films, CdTe is generally grown with thicknesses ranging between 3 and 15 {mu}m, for which it is difficult to measure, by means of optical techniques, absorption coefficients greater than 10{sup 3} cm{sup -1} because nearly full absorption of light should occur below 800 nm. The exact determination of the optical absorption coefficient in detectors on the basis of CdTe is very important since this parameter determines the absorption length at which 90% of the photons with energies over the forbidden zone of the CdTe will be absorbed by this. In CdS/CdTe polycrystalline solar cells the greater efficiency of conversion have been reported for film thicknesses of 10 mm, however, the optimal value of this parameter depends strongly on the method and the variables of growth. The optical absorption coefficient spectrum can be determined by several methods, often involving several approximations and the knowledge of some minority carrier related electronic parameters that reduce their application in general way. In this work we propose to determine the absorption coefficient in CdTe thin films by photoacoustic spectroscopy (PAS), because this technique allow us to obtain the optical absorption spectra in thicker layers and therefore the study of the influence of the several growth and post-growth processes in the optical properties of this thin films. We measure by PAS the optical-absorption coefficients of CdTe thin films in the spectral region near the fundamental absorption edge ranging from 1.0 to 2.4 eV using an open cell in the transmission configuration. The films were deposited on different substrates by the CSVT-HW (hot wall) technique. In order to study the influence of several

  3. The study of response of wide band gap semiconductor detectors using the Geant4

    Directory of Open Access Journals (Sweden)

    Hussain Riaz

    2014-01-01

    Full Text Available The energy dependence on the intrinsic efficiency, absolute efficiency, full energy peak absolute efficiency and peak-to-total ratio have been studied for various wide band gap semiconductor detectors using the Geant4 based Monte Carlo simulations. The detector thickness of 1-4 mm and the area in 16-100 mm2 range were considered in this work. In excellent agreement with earlier work (Rybka et al., [20], the Geant4 simulated values of detector efficiencies have been found to decrease with incident g-ray energy. Both for the detector thickness and the detector area, the increasing trends have been observed for total efficiency as well as for full-energy peak efficiency in 0.1 MeV-50 MeV range. For Cd1-xZnxTe, the detector response remained insensitive to changes in relative proportions of Zn. For various wide band gap detectors studied in this work, the detection efficiency of TlBr was found highest over the entire range of energy, followed by the HgI2, CdTe, and then by CZT.

  4. Development of a modular CdTe detector plane for gamma-ray burst detection below 100 keV

    OpenAIRE

    Ehanno, M.; Amoros, C.; Barret, D.; Lacombe, K.; Pons, R.; Rouaix, G.; Gevin, O.; Limousin, O.; Lugiez, F.; Bardoux, A.; Penquer, A.

    2007-01-01

    We report on the development of an innovative CdTe detector plane (DPIX) optimized for the detection and localization of gamma-ray bursts in the X-ray band (below 100 keV). DPIX is part of an R&D program funded by the French Space Agency (CNES). DPIX builds upon the heritage of the ISGRI instrument, currently operating with great success on the ESA INTEGRAL mission. DPIX is an assembly of 200 elementary modules (XRDPIX) equipped with 32 CdTe Schottky detectors (4x4 mm2, 1 mm thickness) produc...

  5. Fundamental properties of semiconductor materials, and material performance in detectors

    Science.gov (United States)

    Casper, K. J.

    1973-01-01

    Procedures for determining fundamental properties of semiconductor materials, their performance as radiation detectors, and their service life as such detectors are given. Relationships were established between the minority carrier lifetime in the bulk of the material and the charge collection efficiency of the detector.

  6. Pixelated CdTe detectors to overcome intrinsic limitations of crystal based positron emission mammographs

    Science.gov (United States)

    De Lorenzo, G.; Chmeissani, M.; Uzun, D.; Kolstein, M.; Ozsahin, I.; Mikhaylova, E.; Arce, P.; Cañadas, M.; Ariño, G.; Calderón, Y.

    2013-01-01

    A positron emission mammograph (PEM) is an organ dedicated positron emission tomography (PET) scanner for breast cancer detection. State-of-the-art PEMs employing scintillating crystals as detection medium can provide metabolic images of the breast with significantly higher sensitivity and specificity with respect to standard whole body PET scanners. Over the past few years, crystal PEMs have dramatically increased their importance in the diagnosis and treatment of early stage breast cancer. Nevertheless, designs based on scintillators are characterized by an intrinsic deficiency of the depth of interaction (DOI) information from relatively thick crystals constraining the size of the smallest detectable tumor. This work shows how to overcome such intrinsic limitation by substituting scintillating crystals with pixelated CdTe detectors. The proposed novel design is developed within the Voxel Imaging PET (VIP) Pathfinder project and evaluated via Monte Carlo simulation. The volumetric spatial resolution of the VIP-PEM is expected to be up to 6 times better than standard commercial devices with a point spread function of 1 mm full width at half maximum (FWHM) in all directions. Pixelated CdTe detectors can also provide an energy resolution as low as 1.5% FWHM at 511 keV for a virtually pure signal with negligible contribution from scattered events.

  7. CdTe and CdZnTe crystals for room temperature gamma-ray detectors

    CERN Document Server

    Franc, J; Belas, E; Grill, R; Hlidek, P; Moravec, P; Bok, J B

    1999-01-01

    CdTe(Cl) detectors from CdTe single crystals, grown by the Bridgman method from Te-rich melt, were fabricated. The quality of the detectors was tested with sup 5 sup 7 Co and sup 2 sup 4 sup 1 Am sources. In the sup 5 sup 7 Co spectrum low noise is demonstrated by the presence of a 14 keV peak and good resolution approx 7 keV (FWHM) evident from the separation of 122 and 136 keV peaks. A review is given of the state-of-the-art properties of (CdZn)Te single crystals prepared for substrates in the Institute of Physics of Charles University. The quality of samples is tested by measurements of the diffusion length of minority carriers, from which the mobility-lifetime product is evaluated. (author)

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

    Science.gov (United States)

    Gimenez, E. N.; Astromskas, V.; Horswell, I.; Omar, D.; Spiers, J.; Tartoni, N.

    2016-07-01

    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- 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.

  9. High short-circuit current density CdTe solar cells using all-electrodeposited semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Echendu, O.K., E-mail: oechendu@yahoo.com; Fauzi, F.; Weerasinghe, A.R.; Dharmadasa, I.M.

    2014-04-01

    CdS/CdTe and ZnS/CdTe n–n heterojunction solar cells have been fabricated using all-electrodeposited semiconductors. The best devices show remarkable high short-circuit current densities of 38.5 mAcm{sup −2} and 47.8 mAcm{sup −2}, open-circuit voltages of 630 mV and 646 mV and conversion efficiencies of 8.0% and 12.0% respectively. The major strength of these device structures lies in the combination of n–n heterojunction with a large Schottky barrier at the n-CdTe/metal back contact which provides the required band bending for the separation of photo-generated charge carriers. This is in addition to the use of a high quality n-type CdTe absorber layer with high electron mobility. The potential barrier heights estimated for these devices from the current–voltage characteristics exceed 1.09 eV and 1.13 eV for CdS/CdTe and ZnS/CdTe cells respectively. The diode rectification factors of both devices are in excess of four orders of magnitude with reverse saturation current densities of 1.0 × 10{sup −7} Acm{sup −2} and 4.0 × 10{sup −7} Acm{sup −2} respectively. These all-electrodeposited solar cell device structures are currently being studied and developed as an alternative to the well-known p–n junction structures which utilise chemical bath-deposited CdS. The preliminary material growth, device fabrication and assessment results are presented in this paper. - Highlights: • Two-electrode deposition. • High J{sub sc} Schottky barrier solar cells. • CdCl{sub 2} + CdF{sub 2} treatment.

  10. Continued Development of Small-Pixel CZT and CdTe Detectors for Future High-Angular-Resolution Hard X-ray Missions

    Science.gov (United States)

    Krawczynski, Henric

    The Nuclear Spectroscopic Telescope Array (NuSTAR) Small Explorer Mission was launched in June 2012 and has demonstrated the technical feasibility and high scientific impact of hard X-ray astronomy. We propose to continue our current R&D program to develop finely pixelated semiconductor detectors and the associated readout electronics for the focal plane of a NuSTAR follow-up mission. The detector-ASIC (Application Specific Integrated Circuit) package will be ideally matched to the new generation of low-cost, low-mass X-ray mirrors which achieve an order of magnitude better angular resolution than the NuSTAR mirrors. As part of this program, the Washington University group will optimize the contacts of 2x2 cm^2 footprint Cadmium Zinc Telluride (CZT) and Cadmium Telluride (CdTe) detectors contacted with 100x116 hexagonal pixels at a next-neighbor pitch of 200 microns. The Brookhaven National Laboratory group will design, fabricate, and test the next generation of the HEXID ASIC matched to the new X-ray mirrors and the detectors, providing a low-power 100x116 channel ASIC with extremely low readout noise (i.e. with a root mean square noise of 13 electrons). The detectors will be tested with radioactive sources and in the focal plane of high-angular-resolution X-ray mirrors at the X-ray beam facilities at the Goddard and Marshall Space Flight Centers.

  11. CdTe Focal Plane Detector for Hard X-Ray Focusing Optics

    Science.gov (United States)

    Seller, Paul; Wilson, Matthew D.; Veale, Matthew C.; Schneider, Andreas; Gaskin, Jessica; Wilson-Hodge, Colleen; Christe, Steven; Shih, Albert Y.; Inglis, Andrew; Panessa, Marco

    2015-01-01

    The demand for higher resolution x-ray optics (a few arcseconds or better) in the areas of astrophysics and solar science has, in turn, driven the development of complementary detectors. These detectors should have fine pixels, necessary to appropriately oversample the optics at a given focal length, and an energy response also matched to that of the optics. Rutherford Appleton Laboratory have developed a 3-side buttable, 20 millimeter x 20 millimeter CdTe-based detector with 250 micrometer square pixels (80 x 80 pixels) which achieves 1 kiloelectronvolt FWHM (Full-Width Half-Maximum) @ 60 kiloelectronvolts and gives full spectroscopy between 5 kiloelectronvolts and 200 kiloelectronvolts. An added advantage of these detectors is that they have a full-frame readout rate of 10 kilohertz. Working with NASA Goddard Space Flight Center and Marshall Space Flight Center, 4 of these 1 millimeter-thick CdTe detectors are tiled into a 2 x 2 array for use at the focal plane of a balloon-borne hard-x-ray telescope, and a similar configuration could be suitable for astrophysics and solar space-based missions. This effort encompasses the fabrication and testing of flight-suitable front-end electronics and calibration of the assembled detector arrays. We explain the operation of the pixelated ASIC readout and measurements, front-end electronics development, preliminary X-ray imaging and spectral performance, and plans for full calibration of the detector assemblies. Work done in conjunction with the NASA Centers is funded through the NASA Science Mission Directorate Astrophysics Research and Analysis Program.

  12. Thin film CdTe based neutron detectors with high thermal neutron efficiency and gamma rejection for security applications

    Science.gov (United States)

    Smith, L.; Murphy, J. W.; Kim, J.; Rozhdestvenskyy, S.; Mejia, I.; Park, H.; Allee, D. R.; Quevedo-Lopez, M.; Gnade, B.

    2016-12-01

    Solid-state neutron detectors offer an alternative to 3He based detectors, but suffer from limited neutron efficiencies that make their use in security applications impractical. Solid-state neutron detectors based on single crystal silicon also have relatively high gamma-ray efficiencies that lead to false positives. Thin film polycrystalline CdTe based detectors require less complex processing with significantly lower gamma-ray efficiencies. Advanced geometries can also be implemented to achieve high thermal neutron efficiencies competitive with silicon based technology. This study evaluates these strategies by simulation and experimentation and demonstrates an approach to achieve >10% intrinsic efficiency with <10-6 gamma-ray efficiency.

  13. Comparison of ultra-high-resolution parallel-hole collimator materials based on the CdTe pixelated semiconductor SPECT system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Jin; Ryu, Hyun-Ju; Lee, Seung-Wan; Park, Su-Jin; Kim, Hee-Joung, E-mail: hjk1@yonsei.ac.kr

    2013-06-11

    Recently, many studies have sought to improve the sensitivity and spatial resolution of pixelated semiconductor detectors. Spatial resolution can be improved by using a pinhole or pixelated parallel-hole collimator with equal hole and pixel sizes. We compared a pinhole to a pixelated parallel-hole collimator and found that the pixelated parallel-hole collimator had higher sensitivity. Additionally, collimator materials with high absorption efficiency are often used because of their high spatial resolution. The purpose of this study was to compare the quality of images generated using a pixelated semiconductor single photon emission computed tomography (SPECT) system simulated with pixelated parallel-hole collimators of lead, tungsten, gold, and depleted uranium. We performed a simulation study of the PID 350 (Ajat Oy Ltd., Finland) CdTe pixelated semiconductor detector, which consists of small pixels (0.35×0.35 mm{sup 2}), using a Geant4 Application for Tomographic Emission (GATE) simulation. Sensitivities and spatial resolutions were measured for the four collimator materials. To evaluate overall image performance, a hot-rod phantom was designed using GATE simulation. The results showed that with lead, sensitivity was 4.25%, 6.53%, and 10.28% higher than with tungsten, gold, and depleted uranium, respectively. Spatial resolution using depleted uranium was 3.19%, 4.19%, and 8.01% better than that of gold, tungsten, and lead, respectively. Sensitivity and spatial resolution showed little difference among the four types of collimator materials tested. It was difficult to visually distinguish between the reconstructed images of the hot-rod phantom for different collimator materials. The results are promising for notable cost reductions in collimator manufacturing while avoiding impractical and rare materials.

  14. Photo-responsivity characterizations of CdTe films for direct-conversion X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ryun Kyung; Cha, Bo Kyung; Jeon, Sung Chae; Seo, Chang Woo [Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Yun, Seung Man [Pusan National University, Busan (Korea, Republic of)

    2014-08-15

    We have fabricated and investigated thin, polycrystalline, cadmium-telluride (CdTe) films in order to utilize them for optical switching readout layers in direct-conversion X-ray detectors. The polycrystalline CdTe films are fabricated on ITO glasses by using the physical vapor deposition (PVD) method at a slow deposition rate and a pressure of 10{sup -6} torr. CdTe films with thicknesses of 5 and 20 μm are grown. The electrical and the optical characteristics of the CdTe films are investigated by measuring the dark-current and the photo-current as functions of the applied field under different wavelengths of light. Higher photo-currents are generated at the longer wavelengths of light for the same applied voltage. When a higher electrical field is applied to the 20 μm-thick CdTe film, a higher dark-current, a higher photo-current, a larger number of charges, and a higher quantum efficiency are generated.

  15. Design and Fabrication of Silicon Carbide Semiconductor Detectors

    Institute of Scientific and Technical Information of China (English)

    MENG; Xin; LIU; Yang; HE; Gao-kui

    2015-01-01

    The potential of silicon carbide(SiC)for use in semiconductor nuclear radiation detectors has been recognized for years.SiC detectors have now been demonstrated for high-resolution alpha particle and X-ray energy spectrometry,beta ray,gamma-ray,thermal-and fast-neutron

  16. Charge induction in semiconductor detectors with pixellated structure

    NARCIS (Netherlands)

    Samedov, Victor V.

    2007-01-01

    Considerable interest is now being attracted to the next generation of compound semiconductor detectors with pixellated structure in application to x-ray and gamma-astronomy, nuclear spectroscopy and nuclear medicine. The spatial resolution of this type of detectors is mainly determined by the proce

  17. 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.

  18. Imaging of Ra-223 with a small-pixel CdTe detector

    Science.gov (United States)

    Scuffham, J. W.; Pani, S.; Seller, P.; Sellin, P. J.; Veale, M. C.; Wilson, M. D.; Cernik, R. J.

    2015-01-01

    Ra-223 Dichloride (Xofigo™) is a promising new radiopharmaceutical offering survival benefit and palliation of painful bone metastases in patients with hormone-refractory prostate cancer [1]. The response to radionuclide therapy and toxicity are directly linked to the absorbed radiation doses to the tumour and organs at risk respectively. Accurate dosimetry necessitates quantitative imaging of the biodistribution and kinetics of the radiopharmaceutical. Although primarily an alpha-emitter, Ra-223 also has some low-abundance X-ray and gamma emissions, which enable imaging of the biodistribution in the patient. However, the low spectral resolution of conventional gamma camera detectors makes in-vivo imaging of Ra-223 challenging. In this work, we present spectra and image data of anthropomorphic phantoms containing Ra-223 acquired with a small-pixel CdTe detector (HEXITEC) [2] with a pinhole collimator. Comparison is made with similar data acquired using a clinical gamma camera. The results demonstrate the advantages of the solid state detector in terms of scatter rejection and quantitative accuracy of the images. However, optimised collimation is needed in order for the sensitivity to rival current clinical systems. As different dosage levels and administration regimens for this drug are explored in current clinical trials, there is a clear need to develop improved imaging technologies that will enable personalised treatments to be designed for patients.

  19. CdTe and CdZnTe detectors in nuclear medicine

    CERN Document Server

    Scheiber, C

    2000-01-01

    Nuclear medicine diagnostic applications are growing in search for more disease specific or more physiologically relevant imaging. The data are obtained non-invasively from large field gamma cameras or from miniaturised probes. As far as single photon emitters are concerned, often labelled with sup 9 sup 9 sup m Tc (140 keV, gamma), nuclear instrumentation deals with poor counting statistics due to the method of spatial localisation and low contrast to noise due to scatter in the body. Since the 1960s attempts have been made to replace the NaI scintillator by semiconductor detectors with better spectrometric characteristics to improve contrast and quantitative measurements. They allow direct conversion of energy and thus more compact sensors. Room-temperature semiconductor detectors such as cadmium tellure and cadmium zinc tellure have favourable physical characteristics for medical applications which have been investigated in the 1980s. During one decade, they have been used in miniaturised probes such as fo...

  20. A simulation of a CdTe gamma ray detector based on collection efficiency profiles as determined by lateral IBIC

    CERN Document Server

    Vittone, E; Lo Giudice, A; Polesello, P; Manfredotti, C

    1999-01-01

    Collection efficiency profiles as determined by the ion beam-induced charge (IBIC) technique have been considered to evaluate the spectroscopic performance of a cadmium telluride (CdTe) nuclear radiation detector. The dependence of such profiles on the applied bias voltage and the shaping time are presented and discussed on the basis of a theoretical model, which is also used to evaluate the electron/hole collection lengths profiles. Experimental collection efficiency profiles were used as input data of the 'ISIDE' Monte Carlo programme to simulate the CdTe response to gamma rays produced by sup 5 sup 7 Co. A systematic investigation of such spectra obtained under different detection conditions shows the effects of non constant collection efficiency profiles and ballistic deficit on the energy resolution of the detector.

  1. Possible use of CdTe detectors in kVp monitoring of diagnostic x-ray tubes.

    Science.gov (United States)

    Krmar, M; Bucalović, N; Baucal, M; Jovančević, N

    2010-10-01

    It has been suggested that kVp of diagnostic X-ray devices (or maximal energy of x-ray photon spectra) should be monitored routinely; however a standardized noninvasive technique has yet to be developed and proposed. It is well known that the integral number of Compton scattered photons and the intensities of fluorescent x-ray lines registered after irradiation of some material by an x-ray beam are a function of the maximal beam energy. CdTe detectors have sufficient energy resolution to distinguish individual x-ray fluorescence lines and high efficiency for the photon energies in the diagnostic region. Our initial measurements have demonstrated that the different ratios of the integral number of Compton scattered photons and intensities of K and L fluorescent lines detected by CdTe detector are sensitive function of maximal photon energy and could be successfully applied for kVp monitoring.

  2. Simulation studies and spectroscopic measurements of a position sensitive detector based on pixelated CdTe crystals

    CERN Document Server

    Karafasoulis, K; Seferlis, S; Kaissas, I; Lambropoulos, C; Loukas, D; Potiriadis, C

    2010-01-01

    Simulation studies and spectroscopic measurements are presented regarding the development of a pixel multilayer CdTe detector under development in the context of the COCAE project. The instrument will be used for the localization and identification of radioactive sources and radioactively contaminated spots. For the localization task the Compton effect is exploited. The detector response under different radiation fields as well as the overall efficiency of the detector has been evaluated. Spectroscopic measurements have been performed to evaluate the energy resolution of the detector. The efficiency of the event reconstruction has been studied in a wide range of initial photon energies by exploiting the detector's angular resolution measure distribution. Furthermore, the ability of the COCAE detector to localize radioactive sources has been investigated.

  3. Integrated superconducting detectors on semiconductors for quantum optics applications

    Science.gov (United States)

    Kaniber, M.; Flassig, F.; Reithmaier, G.; Gross, R.; Finley, J. J.

    2016-05-01

    Semiconductor quantum photonic circuits can be used to efficiently generate, manipulate, route and exploit nonclassical states of light for distributed photon-based quantum information technologies. In this article, we review our recent achievements on the growth, nanofabrication and integration of high-quality, superconducting niobium nitride thin films on optically active, semiconducting GaAs substrates and their patterning to realize highly efficient and ultra-fast superconducting detectors on semiconductor nanomaterials containing quantum dots. Our state-of-the-art detectors reach external detection quantum efficiencies up to 20 % for ~4 nm thin films and single-photon timing resolutions <72 ps. We discuss the integration of such detectors into quantum dot-loaded, semiconductor ridge waveguides, resulting in the on-chip, time-resolved detection of quantum dot luminescence. Furthermore, a prototype quantum optical circuit is demonstrated that enabled the on-chip generation of resonance fluorescence from an individual InGaAs quantum dot, with a linewidth <15 μeV displaced by 1 mm from the superconducting detector on the very same semiconductor chip. Thus, all key components required for prototype quantum photonic circuits with sources, optical components and detectors on the same chip are reported.

  4. Method for mapping charge pulses in semiconductor radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Prettyman, T.H.

    1998-12-01

    An efficient method for determining the distribution of charge pulses produced by semiconductor detectors is presented. The method is based on a quasi-steady-state model for semiconductor detector operation. A complete description of the model and underlying assumptions is given. Mapping of charge pulses is accomplished by solving an adjoint carrier continuity equation. The solution of the adjoint equation yields Green`s function, a time- and position-dependent map that contains all possible charge pulses that can be produced by the detector for charge generated at discrete locations (e.g., by gamma-ray interactions). Because the map is generated by solving a single, time-dependent problem, the potential for reduction in computational effort over direct mapping methods is significant, particularly for detectors with complex electrode structures. In this paper, the adjoint equation is derived and the mapping method is illustrated for a simple case.

  5. Current responsivity of semiconductor superlattice THz-photon detectors

    DEFF Research Database (Denmark)

    Ignatov, Anatoly A.; Jauho, Antti-Pekka

    1999-01-01

    The current responsivity of a semiconductor superlattice THz-photon detector is calculated using an equivalent circuit model which takes into account the finite matching efficiency between a detector antenna and the superlattice in the presence of parasitic losses. Calculations performed for curr......The current responsivity of a semiconductor superlattice THz-photon detector is calculated using an equivalent circuit model which takes into account the finite matching efficiency between a detector antenna and the superlattice in the presence of parasitic losses. Calculations performed...... for currently available superlattice diodes show that both the magnitudes and the roll-off frequencies of the responsivity are strongly influenced by an excitation of hybrid plasma-Bloch oscillations which are found to be eigenmodes of the system in the THz-frequency band. The expected room temperature values...

  6. Monte Carlo simulation of the response functions of CdTe detectors to be applied in x-ray spectroscopy.

    Science.gov (United States)

    Tomal, A; Santos, J C; Costa, P R; Lopez Gonzales, A H; Poletti, M E

    2015-06-01

    In this work, the energy response functions of a CdTe detector were obtained by Monte Carlo (MC) simulation in the energy range from 5 to 160keV, using the PENELOPE code. In the response calculations the carrier transport features and the detector resolution were included. The computed energy response function was validated through comparison with experimental results obtained with (241)Am and (152)Eu sources. In order to investigate the influence of the correction by the detector response at diagnostic energy range, x-ray spectra were measured using a CdTe detector (model XR-100T, Amptek), and then corrected by the energy response of the detector using the stripping procedure. Results showed that the CdTe exhibits good energy response at low energies (below 40keV), showing only small distortions on the measured spectra. For energies below about 80keV, the contribution of the escape of Cd- and Te-K x-rays produce significant distortions on the measured x-ray spectra. For higher energies, the most important correction is the detector efficiency and the carrier trapping effects. The results showed that, after correction by the energy response, the measured spectra are in good agreement with those provided by a theoretical model of the literature. Finally, our results showed that the detailed knowledge of the response function and a proper correction procedure are fundamental for achieving more accurate spectra from which quality parameters (i.e., half-value layer and homogeneity coefficient) can be determined.

  7. Response functions of Si(Li), SDD and CdTe detectors for mammographic x-ray spectroscopy.

    Science.gov (United States)

    Tomal, A; Cunha, D M; Antoniassi, M; Poletti, M E

    2012-07-01

    In this work, the energy response functions of Si(Li), SDD and CdTe detectors were studied in the mammographic energy range through Monte Carlo simulation. The code was modified to take into account carrier transport effects and the finite detector energy resolution. The results obtained show that all detectors exhibit good energy response at low energies. The most important corrections for each detector were discussed, and the corrected mammographic x-ray spectra obtained with each one were compared. Results showed that all detectors provided similar corrected spectra, and, therefore, they could be used to accurate mammographic x-ray spectroscopy. Nevertheless, the SDD is particularly suitable for clinic mammographic x-ray spectroscopy due to the easier correction procedure and portability.

  8. Characterization of a module with pixelated CdTe detectors for possible PET, PEM and compton camera applications

    Science.gov (United States)

    Ariño-Estrada, G.; Chmeissani, M.; de Lorenzo, G.; Puigdengoles, C.; Martínez, R.; Cabruja, E.

    2014-05-01

    We present the measurement of the energy resolution and the impact of charge sharing for a pixel CdTe detector. This detector will be used in a novel conceptual design for diagnostic systems in the field of nuclear medicine such as positron emission tomography (PET), positron emission mammography (PEM) and Compton camera. The detector dimensions are 10 mm × 10 mm × 2 mm and with a pixel pitch of 1 mm × 1 mm. The pixel CdTe detector is a Schottky diode and it was tested at a bias of -1000 V. The VATAGP7.1 frontend ASIC was used for the readout of the pixel detector and the corresponding single channel electronic noise was found to be σ < 2 keV for all the pixels. We have achieved an energy resolution, FWHM/Epeak, of 7.1%, 4.5% and 0.98% for 59.5, 122 and 511 keV respectively. The study of the charge sharing shows that 16% of the events deposit part of their energy in the adjacent pixel.

  9. K-edge imaging with the XPAD3 hybrid pixel detector, direct comparison of CdTe and Si sensors.

    Science.gov (United States)

    Cassol, F; Portal, L; Graber-Bolis, J; Perez-Ponce, H; Dupont, M; Kronland, C; Boursier, Y; Blanc, N; Bompard, F; Boudet, N; Buton, C; Clémens, J C; Dawiec, A; Debarbieux, F; Delpierre, P; Hustache, S; Vigeolas, E; Morel, C

    2015-07-21

    We investigate the improvement from the use of high-Z CdTe sensors for pre-clinical K-edge imaging with the hybrid pixel detectors XPAD3. We compare XPAD3 chips bump bonded to Si or CdTe sensors in identical experimental conditions. Image performance for narrow energy bin acquisitions and contrast-to-noise ratios of K-edge images are presented and compared. CdTe sensors achieve signal-to-noise ratios at least three times higher than Si sensors within narrow energy bins, thanks to their much higher detection efficiency. Nevertheless Si sensors provide better contrast-to-noise ratios in K-edge imaging when working at equivalent counting statistics, due to their better estimation of the attenuation coefficient of the contrast agent. Results are compared to simulated data in the case of the XPAD3/Si detector. Good agreement is observed when including charge sharing between pixels, which have a strong impact on contrast-to-noise ratios in K-edge images.

  10. Evaluation of mercuric iodide ceramic semiconductor detectors

    Energy Technology Data Exchange (ETDEWEB)

    Schieber, M.; Zuck, A.; Braiman, M.; Nissenbaum, J. [Hebrew Univ., Jerusalem (Israel); Turchetta, R.; Dulinski, W.; Husson, D.; Riester, J.L. [LEPSI (ULP/IN2P3), Strasbourg (France)

    1998-02-01

    Mercuric iodide ceramic radiation detectors, which can act as nuclear particle counters, have been fabricated with single continuos electrical contacts and with linear strip contacts. They have been tested with different kinds of {gamma} and {beta} sources as well as in a high energy beam at CERN. The detectors were also successfully tested for radiation hardness with irradiation of 5*10{sup 14} neutrons/cm{sup 2}. The ratio of detected photons over the number of absorbed photons has been measured with {gamma} sources of different energies, and it ranges from 20% at 44 keV up to about 30% at 660 keV. An absolute efficiency of 70% has been measured for a 350 {mu}m thick detector for {beta} particles emitted by a {sup 90}Sr source. Charge collection efficiency, defined as the amount of charge induced on the electrodes by a mminimum ionizing particle (MIP) traversing the detector, has been measured in two samples. The average collected charge fits well with a linear curve with slope of 35 electrons/(kV/cm) per 100 {mu}m. This result is well described by a dynamic device simulation, where the free carrier mean lifetime is used as a free parameter, adjusted to a value of 1.5 ns, i.e. about 1/100 of the corresponding lifetime in single crystal HgI{sub 2} detectors. The response to MIP has also been studied with a high energy (100 GeV) muon beam in CERN. A preliminary beam profile is presented while a more detailed analysis is still in progress and will be presented elsewhere. These results together with the low cost of the material make ceramic HgI{sub 2} detectors excellent candidates for large area particle tracking and imaging applications, even in a radiation harsh environment. (orig.). 14 refs.

  11. 11th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors

    CERN Document Server

    2013-01-01

    The conference will focus on semiconductor detectors issues relevant to applications in accelerator and space research. Topics include: - large semiconductor systems for calorimetry and tracking applications; - radiation damage measurements and modeling; - radiation hardness of semiconductor detectors; - innovative detectors and electronic systems.

  12. Spectroscopy of low energy solar neutrinos using CdTe detectors

    Science.gov (United States)

    Zuber, K.

    2003-10-01

    The usage of a large amount of CdTe(CdZnTe) semiconductor detectors for solar neutrino spectroscopy in the low energy region is investigated. Several different coincidence signals can be formed on five different isotopes to measure the 7Be neutrino line at 862 keV in real-time. The most promising one is the usage of 116Cd resulting in 227 SNU. The presence of 125Te permits even the real-time detection of pp-neutrinos. A possible antineutrino flux above 713 keV might be detected by capture on 106Cd.

  13. Semiconductors for room temperature nuclear detector applications

    CERN Document Server

    James, Ralph B

    1995-01-01

    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.

  14. Discrimination between normal breast tissue and tumor tissue using CdTe series detector developed for photon-counting mammography

    Science.gov (United States)

    Okamoto, Chizuru; Ihori, Akiko; Yamakawa, Tsutomu; Yamamoto, Shuichiro; Okada, Masahiro; Kato, Misa; Nakajima, Ai; Kodera, Yoshie

    2016-03-01

    We propose a new mammography system using a cadmium telluride (CdTe) series photon-counting detector, having high absorption efficiency over a wide energy range. In a previous study, we showed that the use of high X-ray energy in digital mammography is useful from the viewpoint of exposure dose and image quality. In addition, the CdTe series detector can acquire X-ray spectrum information following transmission through a subject. This study focused on the tissue composition identified using spectral information obtained by a new photon-counting detector. Normal breast tissue consists entirely of adipose and glandular tissues. However, it is very difficult to find tumor tissue in the region of glandular tissue via a conventional mammogram, especially in dense breast because the attenuation coefficients of glandular tissue and tumor tissue are very close. As a fundamental examination, we considered a simulation phantom and showed the difference between normal breast tissue and tumor tissue of various thicknesses in a three-dimensional (3D) scatter plot. We were able to discriminate between both types of tissues. In addition, there was a tendency for the distribution to depend on the thickness of the tumor tissue. Thinner tumor tissues were shown to be closer in appearance to normal breast tissue. This study also demonstrated that the difference between these tissues could be made obvious by using a CdTe series detector. We believe that this differentiation is important, and therefore, expect this technology to be applied to new tumor detection systems in the future.

  15. On the energy response function of a CdTe Medipix2 Hexa detector

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, Thomas, E-mail: t.koenig@dkfz.de [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Zwerger, Andreas [Freiburg Materials Research Center (FMF), Stefan-Meier-Strasse 21, 79104 Freiburg (Germany); Zuber, Marcus; Schuenke, Patrick; Nill, Simeon [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Guni, Ewald [Erlangen Centre for Astroparticle Physics (ECAP), Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Fauler, Alex; Fiederle, Michael [Freiburg Materials Research Center (FMF), Stefan-Meier-Strasse 21, 79104 Freiburg (Germany); Oelfke, Uwe [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)

    2011-08-21

    X-ray imaging based on photon counting pixel detectors has received increased interest during the past years. Attached to a semiconductor of choice, some of these devices enable to resolve the spectral components of an image. This work presents the results from measuring the energy response function of a Medipix2 MXR Hexa detector, where six individual Medipix detectors were bump bonded to a 1 mm thick cadmium telluride sensor in order to form a 3x2 array of 4.2x2.8 cm{sup 2} size. The average FWHM of the photo peak of an {sup 241}Am source was found to be 2.2 and 2.1 keV for single pixels and bias voltages of 200 and 350 V, respectively, across the whole Hexa detector. This corresponds to a relative energy resolution of less than 4%. Adding up all pixel spectra of individual chips lead to an only small deterioration of energy resolution, with line widths of 2.7 and 2.5 keV. In general, a lower detection efficiency was observed for the lower voltage setting, along with a shift of the peak position towards lower energies.

  16. Electrochemical Deposition of CdTe Semiconductor Thin Films for Solar Cell Application Using Two-Electrode and Three-Electrode Configurations: A Comparative Study

    Directory of Open Access Journals (Sweden)

    O. K. Echendu

    2016-01-01

    Full Text Available Thin films of CdTe semiconductor were electrochemically deposited using two-electrode and three-electrode configurations in potentiostatic mode for comparison. Cadmium sulphate and tellurium dioxide were used as cadmium and tellurium sources, respectively. The layers obtained using both configurations exhibit similar structural, optical, and electrical properties with no specific dependence on any particular electrode configuration used. These results indicate that electrochemical deposition (electrodeposition of CdTe and semiconductors in general can equally be carried out using two-electrode system as well as the conventional three-electrode system without compromising the essential qualities of the materials produced. The results also highlight the advantages of the two-electrode configuration in process simplification, cost reduction, and removal of a possible impurity source in the growth system, especially as the reference electrode ages.

  17. Electric field and current transport mechanisms in Schottky CdTe X-ray detectors under perturbing optical radiation.

    Science.gov (United States)

    Cola, Adriano; Farella, Isabella

    2013-07-22

    Schottky CdTe X-ray detectors exhibit excellent spectroscopic performance but suffer from instabilities. Hence it is of extreme relevance to investigate their electrical properties. A systematic study of the electric field distribution and the current flowing in such detectors under optical perturbations is presented here. The detector response is explored by varying experimental parameters, such as voltage, temperature, and radiation wavelength. The strongest perturbation is observed under 850 nm irradiation, bulk carrier recombination becoming effective there. Cathode and anode irradiations evidence the crucial role of the contacts, the cathode being Ohmic and the anode blocking. In particular, under irradiation of the cathode, charge injection occurs and peculiar kinks, typical of trap filling, are observed both in the current-voltage characteristic and during transients. The simultaneous access to the electric field and the current highlights the correlation between free and fixed charges, and unveils carrier transport/collection mechanisms otherwise hidden.

  18. Electric Field and Current Transport Mechanisms in Schottky CdTe X-ray Detectors under Perturbing Optical Radiation

    Directory of Open Access Journals (Sweden)

    Isabella Farella

    2013-07-01

    Full Text Available Schottky CdTe X-ray detectors exhibit excellent spectroscopic performance but suffer from instabilities. Hence it is of extreme relevance to investigate their electrical properties. A systematic study of the electric field distribution and the current flowing in such detectors under optical perturbations is presented here. The detector response is explored by varying experimental parameters, such as voltage, temperature, and radiation wavelength. The strongest perturbation is observed under 850 nm irradiation, bulk carrier recombination becoming effective there. Cathode and anode irradiations evidence the crucial role of the contacts, the cathode being Ohmic and the anode blocking. In particular, under irradiation of the cathode, charge injection occurs and peculiar kinks, typical of trap filling, are observed both in the current-voltage characteristic and during transients. The simultaneous access to the electric field and the current highlights the correlation between free and fixed charges, and unveils carrier transport/collection mechanisms otherwise hidden.

  19. A 2D 4×4 Channel Readout ASIC for Pixelated CdTe Detectors for Medical Imaging Applications

    OpenAIRE

    Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Martínez, Ricardo; Puigdengoles, Carles

    2015-01-01

    We present a 16-channel readout integrated circuit (ROIC) with nanosecond-resolution time to digital converter (TDC) for pixelated Cadmium Telluride (CdTe) gamma-ray detectors. The 4 × 4 pixel array ROIC is the proof of concept of the 10 × 10 pixel array readout ASIC for positron-emission tomography (PET) scanner, positron-emission mammography (PEM) scanner, and Compton gamma camera. The electronics of each individual pixel integrates an analog front-end with switchable gain, an analog to dig...

  20. Possible use of CdTe detectors in kVp monitoring of diagnostic x-ray tubes

    OpenAIRE

    Krmar, M.; Bucalović, N.; Baucal, M.; Jovančević, N.

    2010-01-01

    It has been suggested that kVp of diagnostic X-ray devices (or maximal energy of x-ray photon spectra) should be monitored routinely; however a standardized noninvasive technique has yet to be developed and proposed. It is well known that the integral number of Compton scattered photons and the intensities of fluorescent x-ray lines registered after irradiation of some material by an x-ray beam are a function of the maximal beam energy. CdTe detectors have sufficient energy resolution to dist...

  1. Simulation of charge transport in pixelated CdTe

    OpenAIRE

    Kolstein, M.; G Ariño; Chmeissani, M.; De Lorenzo, G.

    2014-01-01

    The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated semiconductor technology for nuclear medicine applications to achieve an improved image reconstruction without efficiency loss. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 106). The design is based on the use of a pixelated CdTe Schottky detector to have op...

  2. Radiation-hard semiconductor detectors for SuperLHC

    CERN Document Server

    Bruzzi, Mara; Al-Ajili, A A; Alexandrov, P; Alfieri, G; Allport, Philip P; Andreazza, A; Artuso, M; Assouak, S; Avset, B S; Barabash, L; Baranova, E; Barcz, A; Basile, A; Bates, R; Belova, N; Betta, G F D; Biagi, S F; Bilei, G M; Bisello, D; Blue, A; Blumenau, A; Boisvert, V; Bölla, G; Bondarenko, G B; Borchi, E; Borrello, L; Bortoletto, D; Boscardin, M; Bosisio, L; Bowcock, T J V; Brodbeck, T J; Broz, J; Brukhanov, A; Brzozowski, A; Buda, M; Buhmann, P; Buttar, C; Campabadal, F; Campbell, D; Candelori, A; Casse, G; Cavallini, A; Chilingarov, A G; Chren, D; Cindro, V; Citterio, M; Collins, P; Coluccia, R; Contarato, D; Coutinho, J; Creanza, D; Cunningham, W; Cvetkov, V; Davies, G; Dawson, I; De Palma, M; Demina, R; Dervan, P; Dierlamm, A; Dittongo, S; Dobrzanski, L; Dolezal, Z; Dolgolenko, A; Eberlein, T; Eremin, V; Fall, C; Fasolo, F; Ferbel, T; Fizzotti, F; Fleta, C; Focardi, E; Forton, E; Franchenko, S; Fretwurst, E; Gamaz, F; García-Navarro, J E; García, C; Gaubas, E; Genest, M H; Gill, K A; Giolo, K; Glaser, M; Gössling, C; Golovine, V; Gorelov, I; Goss, J; Gouldwell, A; Grégoire, G; Gregori, P; Grigoriev, E; Grigson, C; Grillo, A; Groza, A; Guskov, J; Haddad, L; Harding, R; Härkönen, J; Hauler, F; Hayama, S; Hoeferkamp, M; Honniger, F; Horazdovsky, T; Horisberger, R P; Horn, M; Houdayer, A; Hourahine, B; Hruban, A; Hughes, G; Ilyashenko, Yu S; Irmscher, K; Ivanov, A; Jarasiunas, K; Jin, T; Jones, B K; Jones, R; Joram, C; Jungermann, L; Kalinina, E; Kaminski, P; Karpenko, A; Karpov, A; Kazlauskiene, V; Kazukauskas, V; Khivrich, V; Khomenkov, V P; Kierstead, J A; Klaiber Lodewigs, J M; Kleverman, M; Klingenberg, R; Kodys, P; Kohout, Z; Korjenevski, S; Kowalik, A; Kozlowski, R; Kozodaev, M; Kramberger, G; Krasel, O; Kuznetsov, A; Kwan, S; Lagomarsino, S; Lari, T; Lassila-Perini, K M; Lastovetsky, V F; Latino, G; Latushkin, S T; Lazanu, I; Lazanu, S; Lebel, C; Leinonen, K; Leroy, C; Li, Z; Lindström, G; Lindström, L; Linhart, V; Litovchenko, A P; Litovchenko, P G; Litvinov, V; Lo Giudice, A; Lozano, M; Luczynski, Z; Luukka, Panja; Macchiolo, A; Mainwood, A; Makarenko, L F; Mandic, I; Manfredotti, C; Martí i García, S; Marunko, S; Mathieson, K; Melone, J; Menichelli, D; Meroni, C; Messineo, A; Miglio, S; Mikuz, M; Miyamoto, J; Moll, M; Monakhov, E; Moscatelli, F; Mozzanti, A; Murin, L; Naoumov, D; Nava, F; Nossarzhevska, E; Nummela, S; Nysten, J; Olivero, P; O'Shea, V; Palviainen, T; Paolini, C; Parkes, C; Passeri, D; Pein, U; Pellegrini, G; Perera, L; Petasecca, M; Piatkowski, B; Piemonte, C; Pignatel, G U; Pinho, N; Pintilie, I; Pintilie, L; Polivtsev, L; Polozov, P; Popa, A I; Popule, J; Pospísil, S; Pucker, G; Radicci, V; Rafí, J M; Ragusa, F; Rahman, M; Rando, R; Röder, R; Rohe, T; Ronchin, S; Rott, C; Roy, A; Roy, P; Ruzin, A; Ryazanov, A; Sadrozinski, H F W; Sakalauskas, S; Scaringella, M; Schiavulli, L; Schnetzer, S; Schumm, B; Sciortino, S; Scorzoni, A; Segneri, G; Seidel, S; Seiden, A; Sellberg, G; Sellin, P J; Sentenac, D; Sevilla, S G; Shipsey, I; Sícho, P; Sloan, T; Solar, M; Son, S; Sopko, B; Spencer, N; Stahl, J; Stavitski, I; Stolze, D; Stone, R; Storasta, J; Strokan, N; Strupinski, W; Sudzius, M; Surma, B; Suuronen, J; Suvorov, A; Svensson, B G; Tipton, P; Tomasek, M; Troncon, C; Tsvetkov, A; Tuominen, E; Tuovinen, E; Tuuva, T; Tylchin, M; Uebersee, H; Uher, J; Ullán, M; Vaitkus, J V; Vanni, P; Velthuis, J; Verbitskaya, E; Verzellesi, G; Vrba, V; Wagner, G; Wilhelm, I; Worm, S; Wright, V; Wunstorf, R; Zabierowski, P; Zaluzhny, A; Zavrtanik, M; Zen, M; Zhukov, V; Zorzi, N; de Boer, Wim

    2005-01-01

    An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 10/sup 35/ cm-/sup 2/s-/sup 1/ has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 10 /sup 16/ cm-/sup 2/. The CERN-RD50 project "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Flo...

  3. Development of a pixelated CdTe detector module for a hard-x and gamma-ray imaging spectrometer application

    Science.gov (United States)

    Galvèz, J.-L.; Hernanz, M.; Álvarez, L.; Artigues, B.; Álvarez, J.-M.; Ullán, M.; Lozano, M.; Pellegrini, G.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2016-07-01

    Stellar explosions are relevant and interesting astrophysical phenomena. Since long ago we have been working on the characterization of novae and supernovae in X and gamma-rays, with the use of space missions. We have also been involved in feasibility studies of future instruments in the energy range from several keV up to a few MeV, in collaboration with other research institutes. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae and Classical Novae. In order to fulfil the combined requirement of high detection efficiency with good spatial and energy resolution, an initial module prototype based on CdTe pixel detectors is being developed. The detector dimensions are 12.5mm x 12.5mm x 2mm with a pixel pitch of 1mm x 1mm. Two kinds of CdTe pixel detectors with different contacts have been tested: ohmic and Schottky. Each pixel is bump bonded to a fanout board made of Sapphire substrate and routed to the corresponding input channel of the readout VATAGP7.1 ASIC, to measure pixel position and pulse height for each incident gamma-ray photon. The study is complemented by the simulation of the CdTe module performance using the GEANT 4 and MEGALIB tools, which will help us to optimise the detector design. We will report on the spectroscopy characterisation of the CdTe detector module as well as the study of charge sharing.

  4. Detection Simulation of SiC Semiconductor Detector

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hong Yeop; Kim, Jeong Dong; Lee, Yong Deok; Kim, Ho Dong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    In a high radiation environment, it has received attention as a material for detecting radiation (neutron). As the field of application of a SIC neutron detector, the semiconductor detector used in cosmic rays was proposed by Ruddy. Recently, X-ray and low-energy gamma ray spectrometry with SiC detectors has been reported. Its usability has recently been being proved in neutron dose surveillance in BNCT (Boron-Capture Neutron Therapy), thermal neutron detection in a waste drum, nuclear material surveillance, and fast neutron detection. In addition, in 2006, an experiment was actually performed by Natsume on spent nuclear fuel. SIC is suitable for radiation surveillance in a complex radiation field emitted from spent nuclear fuel and the pyropocess process. In the radiation field of spent nuclear fuel, neutrons and gamma rays are generated. In this research, the performance of a SiC detector made at KAERI was evaluated to obtain a discriminated neutron signal. First, using neutron ({sup 252}Cf), alpha ({sup 241}Am), and gamma ({sup 60}Co) sources, a SiC semi- conductor detector was tested. The energy spectrum in a complex radiation field was simulated using the MCNPX 2.5. Finally, the experimental results by Ruddy were compared with the simulation results. Research result, whether the SiC semiconductor detector operating or not was confirmed through the simulation according to the neutron, gamma. The simulation results were similar to those of Ruddy. A further study is underway to investigate the discriminated neutron signal of a complex radiation field.

  5. Long-Term Stable Surface Treatments on CdTe and CdZnTe Radiation Detectors

    Science.gov (United States)

    Pekarek, Jakub; Belas, Eduard; Zazvorka, Jakub

    2017-04-01

    The spectral resolution and charge collection efficiency (CCE) of cadmium telluride (CdTe) and cadmium zinc telluride (CZT) room-temperature x-ray and gamma-ray detectors are often limited by high surface leakage current due to conducting surface species created during detector fabrication. Surface treatments play a major role in reduction of this surface leakage current. The effect of various types of surface etching and passivation on the leakage current and thereby the spectral energy resolution, CCE, and internal electric field profile of CdTe/CZT detectors has been studied. The main aim of this work is preparation of long-term stable detectors with strongly reduced leakage current. The time stability of the current-voltage characteristic and spectral resolution was investigated during 21 days and 1 year, respectively, after performing surface treatments. Our results suggest that the optimal detector preparation method is chemomechanical polishing in bromine-ethylene glycol solution followed by chemical etching in bromine-methanol solution then surface passivation in potassium hydroxide or ammonium fluoride (NH4F/H2O2). Detectors prepared using this optimal treatment exhibited low leakage current, high spectral resolution, and long-term stability compared with those subjected to other surface preparation methods.

  6. Charge-sharing observations with a CdTe pixel detector irradiated with a{sup 57}Co source

    Energy Technology Data Exchange (ETDEWEB)

    Maiorino, M. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Barcelona (Spain)]. E-mail: maiorino@itas.es; Pellegrini, G. [Centro Nacional de Microelectronica, IMB-CNM-CSIC, UAB Campus, 08193 Barcelona (Spain); Blanchot, G. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Barcelona (Spain); Chmeissani, M. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Barcelona (Spain); Garcia, J. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Barcelona (Spain); Martinez, R. [Centro Nacional de Microelectronica, IMB-CNM-CSIC, UAB Campus, 08193 Barcelona (Spain); Lozano, M. [Centro Nacional de Microelectronica, IMB-CNM-CSIC, UAB Campus, 08193 Barcelona (Spain); Puigdengoles, C. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Barcelona (Spain); Ullan, M. [Centro Nacional de Microelectronica, IMB-CNM-CSIC, UAB Campus, 08193 Barcelona (Spain)

    2006-07-01

    Charge sharing is a limiting factor of detector spatial resolution and contrast in photon counting imaging devices because multiple counts can be induced in adjacent pixels as a result of the spread of the charge cloud generated from a single X-ray photon of high energy in the detector bulk. Although this topic has been debated for a long time, the full impact of charge sharing has not been completely assessed. In this work, we look at the importance of charge sharing in CdTe pixel detectors by exposing such a device to a low-activity (37 kBq){sup 57}Co source, whose main emission line is at 122 keV.The detectors used are 1 mm thick with a pixel pitch of 55 {mu}m. These detectors are bump-bonded to Medipix2 photon-counting chips. This study gives an insight of the impact on the design and operation of pixel detectors coupled to photon-counting devices for imaging applications.

  7. Charge-sharing observations with a CdTe pixel detector irradiated with a 57Co source

    Science.gov (United States)

    Maiorino, M.; Pellegrini, G.; Blanchot, G.; Chmeissani, M.; Garcia, J.; Martinez, R.; Lozano, M.; Puigdengoles, C.; Ullan, M.

    2006-07-01

    Charge sharing is a limiting factor of detector spatial resolution and contrast in photon counting imaging devices because multiple counts can be induced in adjacent pixels as a result of the spread of the charge cloud generated from a single X-ray photon of high energy in the detector bulk. Although this topic has been debated for a long time, the full impact of charge sharing has not been completely assessed. In this work, we look at the importance of charge sharing in CdTe pixel detectors by exposing such a device to a low-activity (37 kBq) 57Co source, whose main emission line is at 122 keV.The detectors used are 1 mm thick with a pixel pitch of 55 μm. These detectors are bump-bonded to Medipix2 photon-counting chips. This study gives an insight of the impact on the design and operation of pixel detectors coupled to photon-counting devices for imaging applications.

  8. Long-Term Stable Surface Treatments on CdTe and CdZnTe Radiation Detectors

    Science.gov (United States)

    Pekarek, Jakub; Belas, Eduard; Zazvorka, Jakub

    2016-12-01

    The spectral resolution and charge collection efficiency (CCE) of cadmium telluride (CdTe) and cadmium zinc telluride (CZT) room-temperature x-ray and gamma-ray detectors are often limited by high surface leakage current due to conducting surface species created during detector fabrication. Surface treatments play a major role in reduction of this surface leakage current. The effect of various types of surface etching and passivation on the leakage current and thereby the spectral energy resolution, CCE, and internal electric field profile of CdTe/CZT detectors has been studied. The main aim of this work is preparation of long-term stable detectors with strongly reduced leakage current. The time stability of the current-voltage characteristic and spectral resolution was investigated during 21 days and 1 year, respectively, after performing surface treatments. Our results suggest that the optimal detector preparation method is chemomechanical polishing in bromine-ethylene glycol solution followed by chemical etching in bromine-methanol solution then surface passivation in potassium hydroxide or ammonium fluoride (NH4F/H2O2). Detectors prepared using this optimal treatment exhibited low leakage current, high spectral resolution, and long-term stability compared with those subjected to other surface preparation methods.

  9. A semiconductor parameter analyzer for ionizing radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Luiz A.P., E-mail: lasantos@cnen.gov.b [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2009-07-01

    Electrometers and ion chamber are normally used to make several types of measurements in a radiation field and there is a unique voltage applied to each detector type. Some electronic devices that are built of semiconductor materials like silicon crystal can also be used for the same purpose. In this case, a characteristic curve of the device must be acquired to choose an operation point which consists of an electrical current or voltage to be applied to the device. Unlike ion chambers, such an electronic device can have different operation points depending on its current versus voltage curve (I x V). The best operation point of the device is also a function of the radiation, energy, dose rate and fluence. The purpose of this work is to show a semiconductor parameter analyzer built to acquire I x V curves as usually, and the innovation here is the fact that it can be used to obtain such a parametric curve when a quad-polar device is under irradiation. The results demonstrate that the system is a very important tool to scientists interested to evaluate a semiconductor detector before, during and after irradiation. A collection of results for devices under an X-ray beam and a neutron fluence are presented: photodiode, phototransistors, bipolar transistor and MOSFET. (author)

  10. Exchange couplings for Mn ions in CdTe: Validity of spin models for dilute magnetic II-VI semiconductors

    Science.gov (United States)

    Linneweber, Thorben; Bünemann, Jörg; Löw, Ute; Gebhard, Florian; Anders, Frithjof

    2017-01-01

    We employ density-functional theory (DFT) in the generalized gradient approximation (GGA) and its extensions GGA +U and GGA+Gutzwiller to calculate the magnetic exchange couplings between pairs of Mn ions substituting Cd in a CdTe crystal at very small doping. DFT(GGA) overestimates the exchange couplings by a factor of 3 because it underestimates the charge-transfer gap in Mn-doped II-VI semiconductors. Fixing the nearest-neighbor coupling J1 to its experimental value in GGA +U , in GGA+Gutzwiller, or by a simple scaling of the DFT(GGA) results provides acceptable values for the exchange couplings at second-, third-, and fourth-neighbor distances in Cd(Mn)Te, Zn(Mn)Te, Zn(Mn)Se, and Zn(Mn)S. In particular, we recover the experimentally observed relation J4>J2,J3 . The filling of the Mn 3 d shell is not integer, which puts the underlying Heisenberg description into question. However, using a few-ion toy model the picture of a slightly extended local moment emerges so that an integer 3 d -shell filling is not a prerequisite for equidistant magnetization plateaus, as seen in experiment.

  11. Reporting detection efficiency for semiconductor neutron detectors: A need for a standard

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Douglas S., E-mail: mcgregor@ksu.ed [S.M.A.R.T. Laboratory, Mechanical and Nuclear Engineering Department, Kansas State University, Manhattan, KS 66506 (United States); Kenneth Shultis, J. [S.M.A.R.T. Laboratory, Mechanical and Nuclear Engineering Department, Kansas State University, Manhattan, KS 66506 (United States)

    2011-03-11

    In the past few years, there has been an increased interest in the development of alternative neutron detection technologies. Included among many promising alternative neutron detection technologies are semiconductor-based neutron detectors. These detectors are typically small and compact, hence those methods used to characterize large gas-filled neutron detectors are inappropriate. Proposed are standard methods that can be used to model the performance of semiconductor neutron detectors and to characterize experimentally the intrinsic efficiency of these detectors.

  12. Thin-film CdTe detector for microdosimetric study of radiation dose enhancement at gold-tissue interface.

    Science.gov (United States)

    Paudel, Nava Raj; Shvydka, Diana; Parsai, E Ishmael

    2016-09-08

    Presence of interfaces between high and low atomic number (Z) materials, often encountered in diagnostic imaging and radiation therapy, leads to radiation dose perturbation. It is characterized by a very narrow region of sharp dose enhancement at the interface. A rapid falloff of dose enhancement over a very short distance from the interface makes the experimental dosimetry nontrivial. We use an in-house-built inexpensive thin-film Cadmium Telluride (CdTe) photodetector to study this effect at the gold-tissue interface and verify our experimental results with Monte Carlo (MC) modeling. Three-micron thick thin-film CdTe photodetectors were fabricated in our lab. One-, ten- or one hundred-micron thick gold foils placed in a tissue-equivalent-phantom were irradiated with a clinical Ir-192 high-dose-rate (HDR) source and current measured with a CdTe detector in each case was compared with the current measured for all uniform tissue-equivalent phantom. Percentage signal enhancement (PSE) due to each gold foil was then compared against MC modeled percentage dose enhancement (PDE), obtained from the geometry mimicking the experimental setup. The experimental PSEs due to 1, 10, and 100 μm thick gold foils at the closest measured distance of 12.5μm from the interface were 42.6 ± 10.8 , 137.0 ± 11.9, and 203.0 ± 15.4, respectively. The corresponding MC modeled PDEs were 38.1 ± 1, 164 ± 1, and 249 ± 1, respectively. The experimental and MC modeled values showed a closer agreement at the larger distances from the interface. The dose enhancement in the vicinity of gold-tissue interface was successfully measured using an in-house-built, high-resolution CdTe-based photodetector and validated with MC simulations. A close agreement between experimental and the MC modeled results shows that CdTe detector can be utilized for mapping interface dose distribution encountered in the application of ionizing radiation.

  13. Various types of semiconductor photocatalysts modified by CdTe QDs and Pt NPs for toluene photooxidation in the gas phase under visible light

    Science.gov (United States)

    Marchelek, M.; Grabowska, E.; Klimczuk, T.; Lisowski, W.; Zaleska-Medynska, A.

    2017-01-01

    A novel synthesis process was used to prepare TiO2 microspheres, TiO2 P-25, SrTiO3 and KTaO3 decorated by CdTe QDs and/or Pt NPs. The effect of semiconductor matrix, presence of CdTe QDs and/or Pt NPs on the semiconductor surface as well as deposition technique of Pt NPs (photodeposition or radiolysis) on the photocatalytic activity were investigated. The as-prepared samples were characterized by X-ray powder diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) with energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), photoluminescence spectrometry (PL), Fourier transform infrared (FT-IR) and Raman spectra, diffuse reflectance spectroscopy (DRS) and BET surface area analysis. The photocatalytic decomposition of toluene in gas phase, activated by light-emitting diodes (LEDs), with the CdTe/Pt nanoparticles-modified TiO2 microspheres, P25, SrTiO3 and KTaO3 semiconductors was investigated under UV-vis and visible irradiation.The results showed that the photoactivity depends on semiconductor matrix. The highest photoactivity under Vis light was observed for KTaO3/CdTe-Pt(R) sample (56% of toluene was decompose after 30 min of irradiation). The efficiency of the most active sample was 3 times higher than result for P25 and two times higher than for unmodified KTaO3.

  14. Dual-sided microstructured semiconductor neutron detectors (DSMSNDs)

    Energy Technology Data Exchange (ETDEWEB)

    Fronk, Ryan G., E-mail: rfronk@ksu.edu [Mechanical and Nuclear Engineering Department, Kansas State University, Manhattan, KS 66506, United States (United States); Bellinger, Steven L.; Henson, Luke C. [Radiation Detection Technologies, Inc., Manhattan, KS 66502 (United States); Ochs, Taylor R.; Smith, Colten T.; Kenneth Shultis, J.; McGregor, Douglas S. [Mechanical and Nuclear Engineering Department, Kansas State University, Manhattan, KS 66506, United States (United States)

    2015-12-21

    Microstructured semiconductor neutron detectors (MSNDs) have in recent years received much interest as high-efficiency replacements for thin-film-coated thermal neutron detectors. The basic device structure of the MSND involves micro-sized trenches that are etched into a vertically-oriented pvn-junction diode that are backfilled with a neutron converting material. Neutrons absorbed within the converting material induce fission of the parent nucleus, producing a pair of energetic charged-particle reaction products that can be counted by the diode. The MSND deep-etched microstructures produce good neutron-absorption and reaction-product counting efficiencies, offering a 10× improvement in intrinsic thermal neutron detection efficiency over thin-film-coated devices. Performance of present-day MSNDs are nearing theoretical limits; streaming paths between the conversion-material backfilled trenches, allow a considerable fraction of neutrons to pass undetected through the device. Dual-sided microstructured semiconductor neutron detectors (DSMSNDs) have been developed that utilize a complementary second set of trenches on the back-side of the device to count streaming neutrons. DSMSND devices are theoretically capable of greater than 80% intrinsic thermal neutron detection efficiency for a 1-mm thick device. The first such prototype DSMSNDs, presented here, have achieved 29.48±0.29% nearly 2× better than MSNDs with similar microstructure dimensions.

  15. Dual-sided microstructured semiconductor neutron detectors (DSMSNDs)

    Science.gov (United States)

    Fronk, Ryan G.; Bellinger, Steven L.; Henson, Luke C.; Ochs, Taylor R.; Smith, Colten T.; Kenneth Shultis, J.; McGregor, Douglas S.

    2015-12-01

    Microstructured semiconductor neutron detectors (MSNDs) have in recent years received much interest as high-efficiency replacements for thin-film-coated thermal neutron detectors. The basic device structure of the MSND involves micro-sized trenches that are etched into a vertically-oriented pvn-junction diode that are backfilled with a neutron converting material. Neutrons absorbed within the converting material induce fission of the parent nucleus, producing a pair of energetic charged-particle reaction products that can be counted by the diode. The MSND deep-etched microstructures produce good neutron-absorption and reaction-product counting efficiencies, offering a 10× improvement in intrinsic thermal neutron detection efficiency over thin-film-coated devices. Performance of present-day MSNDs are nearing theoretical limits; streaming paths between the conversion-material backfilled trenches, allow a considerable fraction of neutrons to pass undetected through the device. Dual-sided microstructured semiconductor neutron detectors (DSMSNDs) have been developed that utilize a complementary second set of trenches on the back-side of the device to count streaming neutrons. DSMSND devices are theoretically capable of greater than 80% intrinsic thermal neutron detection efficiency for a 1-mm thick device. The first such prototype DSMSNDs, presented here, have achieved 29.48±0.29% nearly 2× better than MSNDs with similar microstructure dimensions.

  16. Organic semiconductor nickel phthalocyanine-based photocapacitive and photoresistive detector

    Science.gov (United States)

    Shah, Mutabar; Karimov, Kh S.; Sayyad, M. H.

    2010-07-01

    In this study, the photosensitive organic semiconductor nickel phthalocyanine (NiPc) is investigated as a photocapacitive and photoresistive detector. NiPc thin film is grown by vacuum thermal evaporation on an indium tin oxide (ITO)-coated glass substrate. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is deposited as a top electrode by drop-casting to fabricate the ITO/NiPc/PEDOT:PSS light detector. It has been observed that under the unmodulated filament lamp illumination of up to 9720 lux the capacitance of the detectors increased up to 21, 18 and 4% at a frequency of measuring voltage of 120 Hz, 1 kHz and 10 kHz, respectively, under dark conditions. The change in resistance with the variation in the intensity of light is also investigated. The capacitance and resistance of the light detector decrease with an increase in the frequency. It is assumed that the photocapacitive and photoresistive response of the detector is associated with polarization occurring due to the transfer of photo-generated electrons and holes. The calculated results are in reasonable agreement with the experimental results.

  17. 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.

  18. Carrier Density and Compensation in Semiconductors with Multi Dopants and Multi Transition Energy Levels: The Case of Cu Impurity in CdTe: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wei, S. H.; Ma, J.; Gessert, T. A.; Chin, K. K.

    2011-07-01

    Doping is one of the most important issues in semiconductor physics. The charge carrier generated by doping can profoundly change the properties of semiconductors and their performance in optoelectronic device applications, such as solar cells. Using detailed balance theory and first-principles calculated defect formation energies and transition energy levels, we derive general formulae to calculate carrier density for semiconductors with multi dopants and multi transition energy levels. As an example, we studied CdTe doped with Cu, in which VCd, CuCd, and Cui are the dominant defects/impurities. We show that in this system, when Cu concentration increases, the doping properties of the system can change from a poor p-type, to a poorer p-type, to a better p-type, and then to a poor p-type again, in good agreement with experimental observation of CdTe-based solar cells.

  19. Design and optimization of an analog filter with a CdTe detector for X-ray fluorescence applications

    Science.gov (United States)

    Choi, Hyojeong; Kim, Hui Su; Kim, Young Soo; Ha, Jang Ho; Chai, Jong-Seo

    2016-10-01

    An analog pre-filter circuit for digital pulse processing is designed and optimized for X-ray fluorescence (XRF) applications to replace traditional analog shaping amplifiers. To optimize the pre-filter performance, we characterized noise electrons as a function of the input pulse rise time and decay time of the output pulse by using the full width at half maximum. In addition, gamma-ray energy measurements at room temperature showed that the commercially available CdTe Schottky-type radiation detector with our newly designed and optimized pre-filter circuit exhibited full widths at half maxima of 4.97 (Ba-133, at 53 keV) and 5.56 keV (Am-241, at 59.5 keV), respectively.

  20. Energy Calibration of a CdTe Photon Counting Spectral Detector with Consideration of its Non-Convergent Behavior

    Directory of Open Access Journals (Sweden)

    Jeong Seok Lee

    2016-04-01

    Full Text Available Fast and accurate energy calibration of photon counting spectral detectors (PCSDs is essential for their biomedical applications to identify and characterize bio-components or contrast agents in tissues. Using the x-ray tube voltage as a reference for energy calibration is known to be an efficient method, but there has been no consideration in the energy calibration of non-convergent behavior of PCSDs. We observed that a single pixel mode (SPM CdTe PCSD based on Medipix-2 shows some non-convergent behaviors in turning off the detector elements when a high enough threshold is applied to the comparator that produces a binary photon count pulse. More specifically, the detector elements are supposed to stop producing photon count pulses once the threshold reaches a point of the highest photon energy determined by the tube voltage. However, as the x-ray exposure time increases, the threshold giving 50% of off pixels also increases without converging to a point. We established a method to take account of the non-convergent behavior in the energy calibration. With the threshold-to-photon energy mapping function established by the proposed method, we could better identify iodine component in a phantom consisting of iodine and other components.

  1. Development of CdTe pixel detectors combined with an aluminum Schottky diode sensor and photon-counting ASICs

    Science.gov (United States)

    Toyokawa, H.; Saji, C.; Kawase, M.; Wu, S.; Furukawa, Y.; Kajiwara, K.; Sato, M.; Hirono, T.; Shiro, A.; Shobu, T.; Suenaga, A.; Ikeda, H.

    2017-01-01

    We have been developing CdTe pixel detectors combined with a Schottky diode sensor and photon-counting ASICs. The hybrid pixel detector was designed with a pixel size of 200 μ m by 200 μm and an area of 19 mm by 20 mm or 38.2 mm by 40.2 mm. The photon-counting ASIC, SP8-04F10K, has a preamplifier, a shaper, 3-level window-type discriminators and a 24-bits counter in each pixel. The single-chip detector with 100 by 95 pixels successfully operated with a photon-counting mode selecting X-ray energy with the window comparator and stable operation was realized at 20 degrees C. We have performed a feasibility study for a white X-ray microbeam experiment. Laue diffraction patterns were measured during the scan of the irradiated position in a silicon steel sample. The grain boundaries were identified by using the differentials between adjacent images at each position.

  2. Experimental study of the response of semiconductor detectors to low-energy photons

    CERN Document Server

    Lepy, M C; Laborie, J M; Plagnard, J; Stemmler, P; Teesdale, W J

    2000-01-01

    Six semiconductor detectors (Si(Li) and HPGe) are calibrated in the 1-10 keV energy range by means of tuneable monochromatised synchrotron radiation. Significant improvement in the quality of the response is observed in very recent detectors. A peak shape calibration is established using a modified Hypermet-type function to model the detector response for each energy step; electron effects induce individual background and tail shapes for each detector material. Fano factors for both semiconductor materials are experimentally derived. The efficiency calibration is determined using a proportional counter as reference: the front semiconductor layer acts as a partially active zone.

  3. Vapor-phase epitaxial growth of thick single crystal CdTe on Si substrate for X-ray, gamma ray spectroscopic detector development

    Energy Technology Data Exchange (ETDEWEB)

    Niraula, Madan; Yasuda, Kazuhito; Yamashita, Hayate; Wajima, Yuto; Tsukamoto, Yudai; Matsumoto, Masahiko; Suzuki, Yuta; Takai, Noriaki; Tsukamoto, Yuki; Agata, Yasunori [Nagoya Institute of Technology, Graduate School of Engineering, Gokiso, Showa, Nagoya 466-8555 (Japan)

    2014-07-15

    We investigated MOVPE growth conditions to grow large-area and thick single crystal CdTe layers with uniform material properties directly on (211) Si substrates to develop nuclear radiation detectors. We found that group VI/II precursor flow-ratio as well as rapid thermal annealing performed by interrupting the growth at the initial stage has marked influence on the crystal quality. By using a VI/II precursor ratio of 3.0, and a 900 C anneal performed in flowing hydrogen, we were able to achieve 1-sq inch sized thick single crystal CdTe that showed uniform material properties and high crystal quality throughout the wafer. We further demonstrated that the grown crystals were suitable for fabricating nuclear radiation detector. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Polarisation measurements with a CdTe pixel array detector for Laue hard X-ray focusing telescopes

    CERN Document Server

    Caroli, E; Pisa, A; Stephen, J B; Frontera, F; Castanheira, M T D; Sordo, S; Caroli, Ezio; Silva, Rui M. Curado da; Pisa, Alessandro; Stephen, John B.; Frontera, Filippo; Castanheira, Matilde T. D.; Sordo, Stefano del

    2006-01-01

    Polarimetry is an area of high energy astrophysics which is still relatively unexplored, even though it is recognized that this type of measurement could drastically increase our knowledge of the physics and geometry of high energy sources. For this reason, in the context of the design of a Gamma-Ray Imager based on new hard-X and soft gamma ray focusing optics for the next ESA Cosmic Vision call for proposals (Cosmic Vision 2015-2025), it is important that this capability should be implemented in the principal on-board instrumentation. For the particular case of wide band-pass Laue optics we propose a focal plane based on a thick pixelated CdTe detector operating with high efficiency between 60-600 keV. The high segmentation of this type of detector (1-2 mm pixel size) and the good energy resolution (a few keV FWHM at 500 keV) will allow high sensitivity polarisation measurements (a few % for a 10 mCrab source in 106s) to be performed. We have evaluated the modulation Q factors and minimum detectable polaris...

  5. Study of a new architecture of gamma cameras with Cd/ZnTe/CdTe semiconductors; Etude d'une nouvelle architecture de gamma camera a base de semi-conducteurs CdZnTe /CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Guerin, L

    2007-11-15

    This thesis studies new semi conductors for gammas cameras in order to improve the quality of image in nuclear medicine. The chapter 1 reminds the general principle of the imaging gamma, by describing the radiotracers, the channel of detection and the types of Anger gamma cameras acquisition. The physiological, physical and technological limits of the camera are then highlighted, to better identify the needs of future gamma cameras. The chapter 2 is dedicated to a bibliographical study. At first, semi-conductors used in imaging gamma are presented, and more particularly semi-conductors CDTE and CdZnTe, by distinguishing planar detectors and monolithic pixelated detectors. Secondly, the classic collimators of the gamma cameras, used in clinical routine for the most part of between them, are described. Their geometry is presented, as well as their characteristics, their advantages and their inconveniences. The chapter 3 is dedicated to a state of art of the simulation codes dedicated to the medical imaging and the methods of reconstruction in imaging gamma. These states of art allow to introduce the software of simulation and the methods of reconstruction used within the framework of this thesis. The chapter 4 presents the new architecture of gamma camera proposed during this work of thesis. It is structured in three parts. The first part justifies the use of semiconducting detectors CdZnTe, in particular the monolithic pixelated detectors, by bringing to light their advantages with regard to the detection modules based on scintillator. The second part presents gamma cameras to base of detectors CdZnTe (prototypes or commercial products) and their associated collimators, as well as the interest of an association of detectors CdZnTe in the classic collimators. Finally, the third part presents in detail the HiSens architecture. The chapter 5 describes both software of simulation used within the framework of this thesis to estimate the performances of the Hi

  6. Simulation of the expected performance of a seamless scanner for brain PET based on highly pixelated CdTe detectors.

    Science.gov (United States)

    Mikhaylova, Ekaterina; De Lorenzo, Gianluca; Chmeissani, Mokhtar; Kolstein, Machiel; Cañadas, Mario; Arce, Pedro; Calderón, Yonatan; Uzun, Dilber; Ariño, Gerard; Macias-Montero, José Gabriel; Martinez, Ricardo; Puigdengoles, Carles; Cabruja, Enric

    2014-02-01

    The aim of this work is the evaluation of the design for a nonconventional PET scanner, the voxel imaging PET (VIP), based on pixelated room-temperature CdTe detectors yielding a true 3-D impact point with a density of 450 channels/cm(3), for a total 6 336 000 channels in a seamless ring shaped volume. The system is simulated and evaluated following the prescriptions of the NEMA NU 2-2001 and the NEMA NU 4-2008 standards. Results show that the excellent energy resolution of the CdTe detectors (1.6% for 511 keV photons), together with the small voxel pitch (1 × 1 × 2 mm(3)), and the crack-free ring geometry, give the design the potential to overcome the current limitations of PET scanners and to approach the intrinsic image resolution limits set by physics. The VIP is expected to reach a competitive sensitivity and a superior signal purity with respect to values commonly quoted for state-of-the-art scintillating crystal PETs. The system can provide 14 cps/kBq with a scatter fraction of 3.95% and 21 cps/kBq with a scatter fraction of 0.73% according to NEMA NU 2-2001 and NEMA NU 4-2008, respectively. The calculated NEC curve has a peak value of 122 kcps at 5.3 kBq/mL for NEMA NU 2-2001 and 908 kcps at 1.6 MBq/mL for NEMA NU 4-2008. The proposed scanner can achieve an image resolution of ~ 1 mm full-width at half-maximum in all directions. The virtually noise-free data sample leads to direct positive impact on the quality of the reconstructed images. As a consequence, high-quality high-resolution images can be obtained with significantly lower number of events compared to conventional scanners. Overall, simulation results suggest the VIP scanner can be operated either at normal dose for fast scanning and high patient throughput, or at low dose to decrease the patient radioactivity exposure. The design evaluation presented in this work is driving the development and the optimization of a fully operative prototype to prove the feasibility of the VIP concept.

  7. Simulation of charge transport in pixelated CdTe

    Science.gov (United States)

    Kolstein, M.; Ariño, G.; Chmeissani, M.; De Lorenzo, G.

    2014-12-01

    The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated semiconductor technology for nuclear medicine applications to achieve an improved image reconstruction without efficiency loss. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 106). The design is based on the use of a pixelated CdTe Schottky detector to have optimal energy and spatial resolution. An individual read-out channel is dedicated for each detector voxel of size 1 × 1 × 2 mm3 using an application-specific integrated circuit (ASIC) which the VIP project has designed, developed and is currently evaluating experimentally. The behaviour of the signal charge carriers in CdTe should be well understood because it has an impact on the performance of the readout channels. For this purpose the Finite Element Method (FEM) Multiphysics COMSOL software package has been used to simulate the behaviour of signal charge carriers in CdTe and extract values for the expected charge sharing depending on the impact point and bias voltage. The results on charge sharing obtained with COMSOL are combined with GAMOS, a Geant based particle tracking Monte Carlo software package, to get a full evaluation of the amount of charge sharing in pixelated CdTe for different gamma impact points.

  8. Toward VIP-PIX: A Low Noise Readout ASIC for Pixelated CdTe Gamma-Ray Detectors for Use in the Next Generation of PET Scanners

    OpenAIRE

    Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Puigdengoles, Carles; Lorenzo, Gianluca De; Martínez, Ricardo

    2013-01-01

    VIP-PIX will be a low noise and low power pixel readout electronics with digital output for pixelated Cadmium Telluride (CdTe) detectors. The proposed pixel will be part of a 2D pixel-array detector for various types of nuclear medicine imaging devices such as positron-emission tomography (PET) scanners, Compton gamma cameras, and positron-emission mammography (PEM) scanners. Each pixel will include a SAR ADC that provides the energy deposited with 10-bit resolution. Simultaneously, the self-...

  9. Size-selective precipitation in colloidal semiconductor nanocrystals of CdTe and CdSe: a study by UV-VIS spectroscopy; Precipitacao seletiva de tamanhos em nanoparticulas semicondutoras coloidais de CdTe e CdSe: um estudo por espectroscopia UV-VIS

    Energy Technology Data Exchange (ETDEWEB)

    Viol, Livia Cristina de Souza; Silva, Fernanda Oliveira; Ferreira, Diego Lourenconi; Alves, Jose Luiz Aarestrup; Schiavon, Marco Antonio, E-mail: schiavon@ufsj.edu.b [Universidade Federal de Sao Joao del Rei, MG (Brazil). Dept. de Ciencias Naturais

    2011-07-01

    The post-preparative size-selective precipitation technique was applied in CdTe and CdSe semiconductor nanocrystals prepared via colloidal route in water. The synthesis of CdTe and CdSe nanoparticles and the effect of the post-preparative size-selective precipitation have been characterized mainly by mean of ultraviolet and visible absorption spectroscopy (UV-Vis). It was demonstrated that the size-selective precipitation are able to isolate particles of different sizes and purify the nanoparticles as well. (author)

  10. Semiconductor Detector Developments for High Energy Space Astronomy

    CERN Document Server

    Meuris, Aline

    2014-01-01

    The rise of high energy astrophysics and solar physics in the 20th century is linked to the development of space telescopes; since the 1960s they have given access to the X-ray and gamma-ray sky, revealing the most violent phenomena in the Universe. Research and developments in imaging concepts and sensing materials haven't stopped since yet to improve the sensitivity of the X-ray and gamma-ray observatories. The paper proposes an overview of instrument realizations and focuses on the innovative detection techniques and technologies for applications from 0.1 keV to 10 MeV energy range. Solid-state detectors are prominent solutions for space instrumentation because of their excellent imaging and spectroscopic capabilities with limited volume and power resources. Various detection concepts based on semiconductors (Compton camera, Cd(Zn)Te pixel hybrids, DePFET active pixel sensors) are under design or fabrication for the near-future missions like Astro-H, BepiColombo, Solar Orbiter. New technologies on sensing ...

  11. High frame rate measurements of semiconductor pixel detector readout IC

    Science.gov (United States)

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

    2012-07-01

    We report on high count rate and high frame rate measurements of a prototype IC named FPDR90, designed for readouts of hybrid pixel semiconductor detectors used for X-ray imaging applications. The FPDR90 is constructed in 90 nm CMOS technology and has dimensions of 4 mm×4 mm. Its main part is a matrix of 40×32 pixels with 100 μm×100 μm pixel size. The chip works in the single photon counting mode with two discriminators and two 16-bit ripple counters per pixel. The count rate per pixel depends on the effective CSA feedback resistance and can be set up to 6 Mcps. The FPDR90 can operate in the continuous readout mode, with zero dead time. Due to the architecture of digital blocks in pixel, one can select the number of bits read out from each counter from 1 to 16. Because in the FPDR90 prototype only one data output is available, the frame rate is 9 kfps and 72 kfps for 16 bits and 1 bit readout, respectively (with nominal clock frequency of 200 MHz).

  12. High frame rate measurements of semiconductor pixel detector readout IC

    Energy Technology Data Exchange (ETDEWEB)

    Szczygiel, R., E-mail: robert.szczygiel@agh.edu.pl [AGH University of Science and Technology, Department of Measurement and Instrumentation, Al. Mickiewicza 30, 30-059 Cracow (Poland); Grybos, P.; Maj, P. [AGH University of Science and Technology, Department of Measurement and Instrumentation, Al. Mickiewicza 30, 30-059 Cracow (Poland)

    2012-07-11

    We report on high count rate and high frame rate measurements of a prototype IC named FPDR90, designed for readouts of hybrid pixel semiconductor detectors used for X-ray imaging applications. The FPDR90 is constructed in 90 nm CMOS technology and has dimensions of 4 mm Multiplication-Sign 4 mm. Its main part is a matrix of 40 Multiplication-Sign 32 pixels with 100 {mu}m Multiplication-Sign 100 {mu}m pixel size. The chip works in the single photon counting mode with two discriminators and two 16-bit ripple counters per pixel. The count rate per pixel depends on the effective CSA feedback resistance and can be set up to 6 Mcps. The FPDR90 can operate in the continuous readout mode, with zero dead time. Due to the architecture of digital blocks in pixel, one can select the number of bits read out from each counter from 1 to 16. Because in the FPDR90 prototype only one data output is available, the frame rate is 9 kfps and 72 kfps for 16 bits and 1 bit readout, respectively (with nominal clock frequency of 200 MHz).

  13. Portable gamma- and X-ray analyzers based on CdTe p-i-n detectors

    CERN Document Server

    Khusainov, A K; Bahlanov, S V; Derbin, A V; Ivanov, V V; Lysenko, V V; Morozov, F; Mouratov, V G; Muratova, V N; Petukhov, Y A; Pirogov, A M; Polytsia, O P; Saveliev, V D; Solovei, V A; Yegorov, K A; Zhucov, M P

    1999-01-01

    Several portable instruments are designed using previously reported CdTe detector technology. These can be divided into three groups according to their energy ranges: (1) 3-30 keV XRF analyzers, (2) 5-120 keV wide range XRF analyzers and (3) gamma-ray spectrometers for operation up to 1500 keV. These instruments are used to inspect several hundreds of samples in situ during a working day in applications such as a metal alloy verification at customs control. Heavy metals are identified through a 3-100 mm thick package with these instruments. Surface contamination by heavy metals (for example toxins such as Hg, Th and Pb in housing environmental control), the determination of Pb concentration in gasoline, geophysical control in mining, or nuclear material control are other applications. The weight of these XRF probes is about 1 kg and two electronic designs are used: one with embedded computer and another based on a standard portable PC. The instruments have good precision and high productivity for measurements...

  14. Gamma spectroscopic measurements using the PID350 pixelated CdTe radiation detector

    CERN Document Server

    Karafasoulis, K; Seferlis, S; Papadakis, I; Loukas, D; Lambropoulos, C; Potiriadis, C

    2010-01-01

    Spectroscopic measurements are presented using the PID350 pixelated gamma radiation detectors. A high-speed data acquisition system has been developed in order to reduce the data loss during the data reading in case of a high flux of photons. A data analysis framework has been developed in order to improve the resolution of the acquired energy spectra, using specific calibration parameters for each PID350's pixel. Three PID350 detectors have been used to construct a stacked prototype system and spectroscopic measurements have been performed in order to test the ability of the prototype to localize radioactive sources.

  15. Polarization in CdTe radiation detectors at high X-ray photon fluxes (Conference Presentation)

    Science.gov (United States)

    Franc, Jan; Dědič, Václav; Pekárek, Jakub; Belas, Eduard; Touš, Jan

    2016-09-01

    In this contribution we show an improvement of a spectroscopic response of CZT X-ray detector operating at high fluxes of X-ray tube by simultaneous infrared light illumination with a wavelength of 1200 nm. CZT detectors usually suffer from a polarization effect while their internal electric field can be strongly deformed due to a trapping of photogenerated holes. We describe a mechanism of an optically induced depolarization peaking at photon energy of about 1 eV ( 1240 nm) due to an optical transition of electrons from the valence band to the deep level. The depolarization effect is accompanied by a decrease of the detector current which results in a lower noise entering the preamplifier of detector readout circuit. We have observed that it is possible to restore originally distorted X-ray spectra using additional 1200 nm LED illumination with a photon flux of 10^16 cm^-2s^-1 at approximately two times higher X-ray flux than without LED. The number of detected counts was in the range of 10^5-10^6mm^2s^-1. The restoration of the spectrum by continuous infrared light is accompanied by decrease of dark current. We explain this effect by light induced changes of profile of the electric filed that leads to decrease of the electron current injected from the cathode.

  16. Simulation of one-dimensionally polarized X-ray semiconductor detectors

    NARCIS (Netherlands)

    Engel, K.J.; Herrmann, C.

    2011-01-01

    Abstract: A pixelated X-ray semiconductor detector (=“direct converter”) is studied which contains an inhomogeneous electric field parallel to the depth axis caused by different concentrations of p- or n-doping. The X-ray energy deposition and charge movement within the detector is modeled in Monte-

  17. Development of a 32-detector CdTe matrix for the SVOM ECLAIRs x/gamma camera: tests results of first flight models

    Science.gov (United States)

    Lacombe, K.; Dezalay, J.-P.; Houret, B.; Amoros, C.; Atteia, J.-L.; Aubaret, K.; Billot, M.; Bordon, S.; Cordier, B.; Delaigue, S.; Galliano, M.; Gevin, O.; Godet, O.; Gonzalez, F.; Guillemot, Ph.; Limousin, O.; Mercier, K.; Nasser, G.; Pons, R.; Rambaud, D.; Ramon, P.; Waegebaert, V.

    2016-07-01

    ECLAIRs, a 2-D coded-mask imaging camera on-board the Sino-French SVOM space mission, will detect and locate gamma-ray bursts in near real time in the 4 - 150 keV energy band in a large field of view. The design of ECLAIRs has been driven by the objective to reach an unprecedented low-energy threshold of 4 keV. The detection plane is an assembly of 6400 Schottky CdTe detectors of size 4x4x1 mm3, biased from -200V to -500V and operated at -20°C. The low-energy threshold is achieved thanks to an innovative hybrid module composed of a thick film ceramic holding 32 CdTe detectors ("Detectors Ceramics"), associated to an HTCC ceramic housing a low-noise 32-channel ASIC ("ASIC Ceramics"). We manage the coupling between Detectors Ceramics and ASIC Ceramics in order to achieve the best performance and ensure the uniformity of the detection plane. In this paper, we describe the complete hybrid XRDPIX, of which 50 flight models have been manufactured by the SAGEM company. Afterwards, we show test results obtained on Detectors Ceramics, on ASIC Ceramics and on the modules once assembled. Then, we compare and confront detectors leakage currents and ASIC ENC with the energy threshold values and FWHM measured on XRDPIX modules at the temperature of -20°C by using a calibrated radioactive source of 241Am. Finally, we study the homogeneity of the spectral properties of the 32-detector hybrid matrices and we conclude on general performance of more than 1000 detection channels which may reach the lowenergy threshold of 4 keV required for the future ECLAIRs space camera.

  18. Semiconductor scintillator detector for gamma radiation; Detector cintilador semicondutor para radiacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Laan, F.T.V. der; Borges, V.; Zabadal, J.R.S., E-mail: ftvdl@ufrgs.br, E-mail: borges@ufrgs.br, E-mail: jorge.zabadal@ufrgs.br [Universidade Federal do Rio Grande do Sul (GENUC/DEMEC/UFRGS), Porto Alegre, RS (Brazil). Grupo de Estudos Nucleares. Departamento de Engenharia Mecanica

    2015-07-01

    Nowadays the devices employed to evaluate individual radiation exposition are based on dosimetric films and thermoluminescent crystals, whose measurements must be processed in specific transductors. Hence, these devices carry out indirect measurements. Although a new generation of detectors based on semiconductors which are employed in EPD's (Electronic Personal Dosemeters) being yet available, it high producing costs and large dimensions prevents the application in personal dosimetry. Recent research works reports the development of new detection devices based on photovoltaic PIN diodes, which were successfully employed for detecting and monitoring exposition to X rays. In this work, we step forward by coupling a 2mm anthracene scintillator NE1, which converts the high energy radiation in visible light, generating a Strong signal which allows dispensing the use of photomultipliers. A low gain high performance amplifier and a digital acquisition device are employed to measure instantaneous and cumulative doses for energies ranging from X rays to Gamma radiation up to 2 MeV. One of the most important features of the PIN diode relies in the fact that it can be employed as a detector for ionization radiation, since it requires a small energy amount for releasing electrons. Since the photodiode does not amplify the corresponding photon current, it must be coupled to a low gain amplifier. Therefore, the new sensor works as a scintillator coupled with a photodiode PIN. Preliminary experiments are being performed with this sensor, showing good results for a wide range of energy spectrum. (author)

  19. Instrumentation for characterizing materials and composed semiconductors for ionizing radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Paschoal, Arquimedes J.A.; Leite, Adolfo M.B.; Nazzre, Fabio V.B.; Santos, Luiz A.P. [Centro Regional de Ciencias Nucleares (CRCN/CNEN-PE), Recife, PE (Brazil). Lab. de Instrumentacao Nuclear]. E-mail: lasantos@cnen.gov.br

    2007-07-01

    The purpose of this work is the development of instrumentation for characterizing some type of ionizing radiation detectors. Those detectors are being manufactured by the Nuclear Instrumentation Laboratory at CRCN/Recife and can be used both on photon beam and with particles. Such detectors consist of semiconductor material in the form of films generated by oxide growing or by means of semiconductor material deposition in a substrate. Those materials can be made of metals, semi-metals, composites or semiconductor polymers. Prior to expose those detectors to ionizing radiation, it must be physically and electrically characterized. In this intention it was developed an electromechanical system. An electrical circuit was built to measure the signal from the detector and another circuit to control the movement of four probes (4-points technique) by using a stepper motor and the micro stepping technique avoiding damage to the detector. This system can be of interest to researchers that work with a sort of semiconductor materials in the form of thin film and in nanotechnological processes aiming the design of radiation ionizing detectors. (author)

  20. Using a CdTe detector for 125Te Mössbauer Spectroscopy: Application to the f-factor in Mg3TeO6

    Science.gov (United States)

    Bargholtz, Chr; Blomquist, J.; Fumero, E.; Mårtensson, L.; Einarsson, L.; Wäppling, R.

    2000-09-01

    An apparatus for Mössbauer spectroscopy has been developed with a cadmium telluride (CdTe) γ-ray detector. Complete data regarding γ-ray energy, source velocity, temperature and real time are stored for off-line analysis. The apparatus has been used to study the spectrum of 125Te in Mg 3TeO 6 at room temperature. The 35.5 keV transition of 125Te in Mg 3TeO 6 was found to have a recoil-free fraction f=0.392(5) corresponding to a Debye temperature θ=352(3) K.

  1. Energy-windowed, pixellated X-ray diffraction using the Pixirad CdTe detector

    Science.gov (United States)

    O'Flynn, D.; Bellazzini, R.; Minuti, M.; Brez, A.; Pinchera, M.; Spandre, G.; Moss, R.; Speller, R. D.

    2017-01-01

    X-ray diffraction (XRD) is a powerful tool for material identification. In order to interpret XRD data, knowledge is required of the scattering angles and energies of X-rays which interact with the sample. By using a pixellated, energy-resolving detector, this knowledge can be gained when using a spectrum of unfiltered X-rays, and without the need to collimate the scattered radiation. Here we present results of XRD measurements taken with the Pixirad detector and a laboratory-based X-ray source. The cadmium telluride sensor allows energy windows to be selected, and the 62 μm pixel pitch enables accurate spatial information to be preserved for XRD measurements, in addition to the ability to take high resolution radiographic images. Diffraction data are presented for a variety of samples to demonstrate the capability of the technique for materials discrimination in laboratory, security and pharmaceutical environments. Distinct diffraction patterns were obtained, from which details on the molecular structures of the items under study were determined.

  2. Exploring graphene field effect transistor devices to improve spectral resolution of semiconductor radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Richard Karl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen Wayne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Jeffrey B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hamilton, Allister B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-12-01

    Graphene, a planar, atomically thin form of carbon, has unique electrical and material properties that could enable new high performance semiconductor devices. Graphene could be of specific interest in the development of room-temperature, high-resolution semiconductor radiation spectrometers. Incorporating graphene into a field-effect transistor architecture could provide an extremely high sensitivity readout mechanism for sensing charge carriers in a semiconductor detector, thus enabling the fabrication of a sensitive radiation sensor. In addition, the field effect transistor architecture allows us to sense only a single charge carrier type, such as electrons. This is an advantage for room-temperature semiconductor radiation detectors, which often suffer from significant hole trapping. Here we report on initial efforts towards device fabrication and proof-of-concept testing. This work investigates the use of graphene transferred onto silicon and silicon carbide, and the response of these fabricated graphene field effect transistor devices to stimuli such as light and alpha radiation.

  3. X-ray diffraction study of epitaxial heterostructures of II-VI CdTe and ZnTe semiconductors; Etude par diffraction de rayons X d`heterostructures epitaxiees a base des semi-conducteurs II-VI CdTe et ZnTe

    Energy Technology Data Exchange (ETDEWEB)

    Bouchet-Boudet, N.

    1996-10-07

    This work deals with the structural study of II-VI semiconductor (CdTe and ZnTe) heterostructures by X-ray diffraction and reflectivity. These heterostructures have a high lattice parameter misfit and are grown by Molecular Beam Epitaxy. Two main subjects are developed: the characterization of ZnTe wires, grown by step propagation on a CdTe (001) vicinal surface, and the study of the vertical correlations in Cd{sub 0.8}Zn{sub 0.2}Te / CdTe superlattices and superlattices made of ZnTe fractional layers spaced by CdTe. The growth of organised system is up to date; its aim is to realize quantum boxes (or wires) superlattices which are laterally and vertically ordered. The deformation along the growth axis induced by a ZnTe fractional layer inserted in a CdTe matrix is modelled, in the kinematical approximation, to reproduce the reflectivity measured around the substrate (004) Bragg peak. The lateral periodicity of the wires, deposited on a vicinal surface is a new and difficult subject. Some results are obtained on a vertical superlattice grown on a 1 deg. mis-cut surface. The in-plane and out-of-plane correlation lengths of a Cd{sub 0.8}Zn{sub 0.2}Te / CdTe superlattice are deduced from the diffused scattered intensity measured at grazing incidence. The calculations are made within the `distorted Wave Born Approximation`. The vertical correlation in ZnTe boxes (or wines) superlattices can be measured around Bragg peaks. It is twice bigger in a superlattice grown on a 2 deg. mis-cut substrate than a nominal one. (author). 74 refs.

  4. High-sensitivity visible-blind UV detectors made with organic semiconductors

    Science.gov (United States)

    Yu, Gang; Cao, Yong; Srdanov, Gordana

    1999-04-01

    High sensitivity visible-blind UV detectors were fabricated with organic semiconductors. The photo-sensitivity at 350 nm reaches 75 mA/Watt, corresponding to quantum efficiency of approximately 27% el/ph. The visible/UV suppression ratio is more than 10(superscript 4) without optical filters. These UV detectors are of linear intensity dependence with fast response time. The simple fabrication process allows these UV detectors to be made in large size, in flexible forms or onto non-planar substrates with low cost. The fabrication process also allows these UV detectors to be integrated with electronic devices or optical devices.

  5. High-efficiency microstructured semiconductor neutron detectors that are arrayed, dual-integrated, and stacked

    Energy Technology Data Exchange (ETDEWEB)

    Bellinger, Steven L., E-mail: slb3888@ksu.edu [Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States); Fronk, Ryan G. [Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States); Sobering, Timothy J. [Electronics Design Laboratory, Kansas State University, Manhattan, KS 66506 (United States); McGregor, Douglas S. [Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States)

    2012-07-15

    Silicon diodes with large aspect ratio 3D microstructures backfilled with {sup 6}LiF show a significant increase in neutron detection efficiency beyond that of conventional thin-film coated planar devices. Described in this work are advancements in the technology using detector stacking methods and summed-detector 6 Multiplication-Sign 6-element arraying methods to dramatically increase the sensitivity to thermal neutrons. The intrinsic detection efficiency of the 6 Multiplication-Sign 6 array for normal-incident 0.0253 eV neutrons was found 6.8% compared against a calibrated {sup 3}He proportional counter. - Highlights: Black-Right-Pointing-Pointer Solid-state semiconductor neutron detectors utilizing {sup 6}LiF. Black-Right-Pointing-Pointer Large aspect ratio 3D microstructured silicon diodes. Black-Right-Pointing-Pointer Arrayed solid-state semiconductor neutron detectors.

  6. Epitaxial silicon semiconductor detectors, past developments, future prospects

    Energy Technology Data Exchange (ETDEWEB)

    Gruhn, C.R.

    1976-01-01

    A review of the main physical characteristics of epitaxial silicon as it relates to detector development is presented. As examples of applications results are presented on (1) epitaxial silicon avalanche diodes (ESAD); signal-to-noise, non-linear aspects of the avalanche gain mechanism, gain-bandwidth product, (2) ultrathin epitaxial silicon surface barrier (ESSB) detectors, response to heavy ions, (3) an all-epitaxial silicon diode (ESD), response to heavy ions, charge transport and charge defect. Future prospects of epitaxial silicon as it relates to new detector designs are summarized.

  7. Epitaxial silicon semiconductor detectors: past developments, future prospects

    Energy Technology Data Exchange (ETDEWEB)

    Gruhn, C.R.

    1977-02-01

    A review of the main physical characteristics of epitaxial silicon as it relates to detector development is presented. As examples of applications results are presented on (1) epitaxial silicon avalanche diodes (ESAD); signal-to-noise, non-linear aspects of the avalanche gain mechanism, gain-bandwidth product, (2) ultrathin epitaxial silicon surface barrier (ESSB) detectors, response to heavy ions, (3) an all-epitaxial silicon diode (ESD), response to heavy ions, charge transport and charge defect. Future prospects of epitaxial silicon as it relates to new detector designs are summarized.

  8. An evaluation of semiconductor and ionization chamber detectors for diagnostic x-ray dosimetry measurements.

    Science.gov (United States)

    Martin, C J

    2007-08-07

    Dosemeters for performance testing of x-ray equipment may utilize semiconductor technology or ionization chambers (ICs). Semiconductor dosemeters incorporate several elements into the detectors from which compensation for variations in response with photon energy is derived. The design of the detectors influences their response with angle and this is different from that of ICs. The responses of semiconductor detectors (SDs) and ICs to x-ray beams with a variety of radiation qualities have been measured in order to assess differences in response. Measurements have been made with experimental arrangements simulating use of the detectors in performance testing of digital radiography and fluoroscopy equipment. Results show that differences in photon energy responses between the detectors are small, but because ICs are sensitive to radiation incident from all angles, they record more scattered radiation than SDs. Implications of differences in detector responses are discussed and recommendations made about their use. SDs are more appropriate for measurements of image receptor doses and are recommended for setting up automatic exposure control devices for digital radiography. ICs are suitable for assessment of patient entrance surface dose rate measurements. Correction factors that could be applied to allow comparisons between measurements with different dosemeters are proposed.

  9. Non-streaming high-efficiency perforated semiconductor neutron detectors, methods of making same and measuring wand and detector modules utilizing same

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Douglas S. (Riley, KS); Shultis, John K. (Manhattan, KS); Rice, Blake B. (Manhattan, KS); McNeil, Walter J. (Winnfield, KS); Solomon, Clell J. (Wichita, KS); Patterson, Eric L. (Manhattan, KS); Bellinger, Steven L. (Manhattan, KS)

    2010-12-21

    Non-streaming high-efficiency perforated semiconductor neutron detectors, method of making same and measuring wands and detector modules utilizing same are disclosed. The detectors have improved mechanical structure, flattened angular detector responses, and reduced leakage current. A plurality of such detectors can be assembled into imaging arrays, and can be used for neutron radiography, remote neutron sensing, cold neutron imaging, SNM monitoring, and various other applications.

  10. Alpha-ray spectrometry at high temperature by using a compound semiconductor detector.

    Science.gov (United States)

    Ha, Jang Ho; Kim, Han Soo

    2013-11-01

    The use of conventional radiation detectors in harsh environments is limited by radiation damage to detector materials and by temperature constraints. We fabricated a wide-band gap semiconductor radiation detector based on silicon carbide. All the detector components were considered for an application in a high temperature environment like a nuclear reactor core. The radiation response, especially to alpha particles, was measured using an (241)Am source at variable operating voltages at room temperature in the air. The temperature on detector was controlled from 30°C to 250°C. The alpha-particle spectra were measured at zero bias operation. Even though the detector is operated at high temperature, the energy resolution as a function of temperature is almost constant within 3.5% deviation.

  11. Experimental characterization of semiconductor-based thermal neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); Bortot, D.; Pola, A.; Introini, M.V.; Lorenzoli, M. [Politecnico di Milano, Dipartimento di Energia, via La Masa 34, 20156 Milano (Italy); INFN—Milano, Via Celoria 16, 20133 Milano (Italy); Gómez-Ros, J.M. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); CIEMAT, Av. Complutense 40, 28040 Madrid (Spain); Sacco, D. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); INAIL—DIT, Via di Fontana Candida 1, 00040 Monteporzio Catone (Italy); Esposito, A.; Gentile, A.; Buonomo, B. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); Palomba, M.; Grossi, A. [ENEA Triga RC-1C.R. Casaccia, via Anguillarese 301, 00060 S. Maria di Galeria, Roma (Italy)

    2015-04-21

    In the framework of NESCOFI@BTF and NEURAPID projects, active thermal neutron detectors were manufactured by depositing appropriate thickness of {sup 6}LiF on commercially available windowless p–i–n diodes. Detectors with different radiator thickness, ranging from 5 to 62 μm, were manufactured by evaporation-based deposition technique and exposed to known values of thermal neutron fluence in two thermal neutron facilities exhibiting different irradiation geometries. The following properties of the detector response were investigated and presented in this work: thickness dependence, impact of parasitic effects (photons and epithermal neutrons), linearity, isotropy, and radiation damage following exposure to large fluence (in the order of 10{sup 12} cm{sup −2})

  12. Cryogenic Semiconductor Detectors: Simulation of Signal Formation & Irradiation Beam Test

    CERN Document Server

    AUTHOR|(CDS)2091318; Stamoulis, G; Vavougios, D

    The Beam Loss Monitoring system of the Large Hadron Collider is responsible for the pro- tection of the machine from damage and for the prevention of a magnet quench. Near the interaction points of the LHC, in the triplet magnets area, the BLMs are sensitive to the collision debris, limiting their ability to distinguish beam loss signal from signal caused due to the collision products. Placing silicon & diamond detectors inside the cold mass of the mag- nets, in liquid helium temperatures, would provide significant improvement to the precision of the measurement of the energy deposition in the superconducting coil of the magnet. To further study the signal formation and the shape of the transient current pulses of the aforementioned detectors in cryogenic temperatures, a simulation application has been developed. The application provides a fast way of determining the electric field components inside the detectors bulk and then introduces an initial charge distribution based on the properties of the radiat...

  13. Organic semiconductors as real-time radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, T., E-mail: tsuzuki@hep.sc.niigata-u.ac.jp [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Miyata, H., E-mail: miyata@hep.sc.niigata-u.ac.jp [Department of Physics, Niigata University, Niigata 950-2181 (Japan); Katsumata, M. [Department of Physics, Niigata University, Niigata 950-2181 (Japan); Nakano, S.; Matsuda, K. [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Tamura, M. [Carlit Holdings Co., Ltd., Tokyo 104-0031 (Japan)

    2014-11-01

    In this study, the possibility of using π-conjugated organic semiconducting polymers as real-time radiation detectors was explored. Polyaniline (PAni) was used to fabricate radiation sensors because of its relative long-term stability in air. Each fabricated sensor was then subjected to irradiation by α- and β-particles, and the real-time response was measured. The multichannel analyzer (MCA) data of the response signal for each irradiation was acquired and the detection efficiency, relative to the electrode bias voltage of the detector, was extracted.

  14. Materials processing threshold report. 1: Semiconductor crystals for infrared detectors

    Science.gov (United States)

    Sager, E. V.; Thompson, T. R.; Nagler, R. G.

    1980-01-01

    An extensive search was performed of the open literature pertaining to infrared detectors to determine what constitutes a good detector and in what way performance is limited by specific material properties. Interviews were conducted with a number of experts in the field to assess their perceptions of the state of the art and of the utility of zero-gravity processing. Based on this information base and on a review of NASA programs in crystal growth and infrared sensors, NASA program goals were reassessed and suggestions are presented as to possible joint and divergent efforts between NASA and DOD.

  15. Dark Current Characteristics of a Radiation Detector Array Developed Using MOVPE-Grown Thick CdTe Layers on Si Substrate

    Science.gov (United States)

    Yasuda, K.; Niraula, M.; Fujimura, N.; Tachi, T.; Inuzuka, H.; Namba, S.; Muramatsu, S.; Kondo, T.; Agata, Y.

    2012-10-01

    We present reverse bias current (dark current) characteristics of a two-dimensional monolithic pixel-type nuclear radiation detector array fabricated using metalorganic vapor-phase epitaxy (MOVPE)-grown thick CdTe epitaxial layers on Si substrate. The (14 × 8) pixel array was formed by cutting deep vertical trenches using a dicing saw, where each pixel possesses a p-CdTe/ n-CdTe/ n +-Si heterojunction diode structure. The dark currents showed pixel-to-pixel variations when measured at higher applied biases exceeding 100 V. The dark current had a dependence on the pixel thickness, where pixels with lower CdTe thickness exhibited higher currents. Moreover, the temperature dependence of the dark current revealed that a deep level with activation energy of around 0.6 eV is responsible for the observed dark currents and their pixel-to-pixel variation. We discuss that the effective ratio of Te to Cd at the growth surface is a major factor that controls the thickness variation, and is also responsible for the formation of 0.6 eV deep levels.

  16. Dynamics of native oxide growth on CdTe and CdZnTe X-ray and gamma-ray detectors

    Science.gov (United States)

    Zázvorka, Jakub; Franc, Jan; Beran, Lukáš; Moravec, Pavel; Pekárek, Jakub; Veis, Martin

    2016-01-01

    Abstract We studied the growth of the surface oxide layer on four different CdTe and CdZnTe X-ray and gamma-ray detector-grade samples using spectroscopic ellipsometry. We observed gradual oxidization of CdTe and CdZnTe after chemical etching in bromine solutions. From X-ray photoelectron spectroscopy measurements, we found that the oxide consists only of oxygen bound to tellurium. We applied a refined theoretical model of the surface layer to evaluate the spectroscopic ellipsometry measurements. In this way we studied the dynamics and growth rate of the oxide layer within a month after chemical etching of the samples. We observed two phases in the evolution of the oxide layer on all studied samples. A rapid growth was visible within five days after the chemical treatment followed by semi-saturation and a decrease in the growth rate after the first week. After one month all the samples showed an oxide layer about 3 nm thick. The oxide thickness was correlated with leakage current degradation with time after surface preparation. PMID:27933118

  17. Edge effects in a small pixel CdTe for X-ray imaging

    Science.gov (United States)

    Duarte, D. D.; Bell, S. J.; Lipp, J.; Schneider, A.; Seller, P.; Veale, M. C.; Wilson, M. D.; Baker, M. A.; Sellin, P. J.; Kachkanov, V.; Sawhney, K. J. S.

    2013-10-01

    Large area detectors capable of operating with high detection efficiency at energies above 30 keV are required in many contemporary X-ray imaging applications. The properties of high Z compound semiconductors, such as CdTe, make them ideally suitable to these applications. The STFC Rutherford Appleton Laboratory has developed a small pixel CdTe detector with 80 × 80 pixels on a 250 μm pitch. Historically, these detectors have included a 200 μm wide guard band around the pixelated anode to reduce the effect of defects in the crystal edge. The latest version of the detector ASIC is capable of four-side butting that allows the tiling of N × N flat panel arrays. To limit the dead space between modules to the width of one pixel, edgeless detector geometries have been developed where the active volume of the detector extends to the physical edge of the crystal. The spectroscopic performance of an edgeless CdTe detector bump bonded to the HEXITEC ASIC was tested with sealed radiation sources and compared with a monochromatic X-ray micro-beam mapping measurements made at the Diamond Light Source, U.K. The average energy resolution at 59.54 keV of bulk and edge pixels was 1.23 keV and 1.58 keV, respectively. 87% of the edge pixels present fully spectroscopic performance demonstrating that edgeless CdTe detectors are a promising technology for the production of large panel radiation detectors for X-ray imaging.

  18. X-ray imaging with photon counting hybrid semiconductor pixel detectors

    CERN Document Server

    Manolopoulos, S; Campbell, M; Snoeys, W; Heijne, Erik H M; Pernigotti, E; Raine, C; Smith, K; Watt, J; O'Shea, V; Ludwig, J; Schwarz, C

    1999-01-01

    Semiconductor pixel detectors, originally developed for particle physics experiments, have been studied as X-ray imaging devices. The performance of devices using the OMEGA 3 read-out chip bump-bonded to pixellated silicon semiconductor detectors is characterised in terms of their signal-to-noise ratio when exposed to 60 kVp X-rays. Although parts of the devices achieve values of this ratio compatible with the noise being photon statistics limited, this is not found to hold for the whole pixel matrix, resulting in the global signal-to-noise ratio being compromised. First results are presented of X-ray images taken with a gallium arsenide pixel detector bump-bonded to a new read-out chip, (MEDIPIX), which is a single photon counting read-out chip incorporating a 15-bit counter in every pixel. (author)

  19. X-ray imaging with photon counting hybrid semiconductor pixel detectors

    Energy Technology Data Exchange (ETDEWEB)

    Manolopoulos, S.; Bates, R.; Campbell, M.; Snoeys, W.; Heijne, E.; Pernigotti, E.; Raine, C.; Smith, K. E-mail: k.smith@physics.gla.ac.uk; Watt, J.; O' Shea, V.; Ludwig, J.; Schwarz, C

    1999-09-11

    Semiconductor pixel detectors, originally developed for particle physics experiments, have been studied as X-ray imaging devices. The performance of devices using the {omega}3 read-out chip bump-bonded to pixellated silicon semiconductor detectors is characterised in terms of their signal-to-noise ratio when exposed to 60 kVp X-rays. Although parts of the devices achieve values of this ratio compatible with the noise being photon statistics limited, this is not found to hold for the whole pixel matrix, resulting in the global signal-to-noise ratio being compromised. First results are presented of X-ray images taken with a gallium arsenide pixel detector bump-bonded to a new read-out chip, (MEDIPIX), which is a single photon counting read-out chip incorporating a 15-bit counter in every pixel. (author)

  20. Quantum coherence in semiconductor nanostructures for improved lasers and detectors.

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Weng Wah Dr. (; .); Lyo, Sungkwun Kenneth; Cederberg, Jeffrey George; Modine, Normand Arthur; Biefeld, Robert Malcolm

    2006-02-01

    The potential for implementing quantum coherence in semiconductor self-assembled quantum dots has been investigated theoretically and experimentally. Theoretical modeling suggests that coherent dynamics should be possible in self-assembled quantum dots. Our experimental efforts have optimized InGaAs and InAs self-assembled quantum dots on GaAs for demonstrating coherent phenomena. Optical investigations have indicated the appropriate geometries for observing quantum coherence and the type of experiments for observing quantum coherence have been outlined. The optical investigation targeted electromagnetically induced transparency (EIT) in order to demonstrate an all optical delay line.

  1. Influence of backscattering on the spatial resolution of semiconductor X-ray detectors

    Science.gov (United States)

    Hoheisel, M.; Korn, A.; Giersch, J.

    2005-07-01

    Pixelated X-ray detectors using semiconductor layers or scintillators as absorbers are widely used in high-energy physics, medical diagnosis, or non-destructive testing. Their good spatial resolution performance makes them particularly suitable for applications where fine details have to be resolved. Intrinsic limitations of the spatial resolution have been studied in previous simulations. These simulations focused on interactions inside the conversion layer. Transmitted photons were treated as a loss. In this work, we also implemented the structure behind the conversion layer to investigate the impact of backscattering inside the detector setup. We performed Monte Carlo simulations with the program ROSI ( Roentgen Simulation) which is based on the well-established EGS4 algorithm. Line-spread functions of different fully implemented detectors were simulated. In order to characterize the detectors' spatial resolution, the modulation transfer functions (MTF) were calculated. The additional broadening of the line-spread function by carrier transport has been ignored in this work. We investigated two different detector types: a directly absorbing pixel detector where a semiconductor slab is bump-bonded to a readout ASIC such as the Medipix-2 setup with Si or GaAs as an absorbing semiconductor layer, and flat-panel detectors with a Se or a CsI converter. We found a significant degradation of the MTF compared to the case without backscattering. At energies above the K-edge of the backscattering material the spatial resolution drops and can account for the observed low-frequency drop of the MTF. Ignoring this backscatter effect might lead to misinterpretations of the charge sharing effect in counting pixel detectors.

  2. Extensive testing of Schottky CdTe detectors for the ECLAIRs X-Gamma-ray Camera on board the SVOM mission

    CERN Document Server

    Nadege, Remoue; Olivier, Godet; Pierre, Mandrou

    2010-01-01

    We report on an on-going test campaign of more than 5000 Schottky CdTe detectors (4x4x1 mm^3), over a sample of twelve thousands, provided by Acrorad Co., Ltd (Japan). 6400 of these detectors will be used to build the detection plane of the ECLAIRs camera on the Chinese-French gamma-ray burst mission SVOM. These tests are mandatory to fulfill the prime requirement of ECLAIRs to detect gamma-ray burst photons down to 4 keV. The detectors will be operated at -20C under a reverse bias of 600 V. We found that 78% of the detectors already tested could be considered for the flight model. We measured a mean energy resolution of 1.8 keV at 59.6 keV. We investigated the polarization effect first at room temperature and low bias voltage for faster analysis. We found that the spectroscopic degradation in quantum efficiency, gain and energy resolution, starts as soon as the bias is turned on: first slowly and then dramatically after a time t_p which depends on the temperature and the voltage value. Preliminary tests unde...

  3. Structural and electrical properties of polycrystalline CdTe films for direct X-ray imaging detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Bo Kyung, E-mail: goldrain99@kaist.ac.kr [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Repulic of Korea (Korea, Republic of); Yang, Keedong [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Repulic of Korea (Korea, Republic of); Cha, Eun Seok; Yong, Seok-Min [Department of Materials Science and Engineering, KAIST, Daejeon, Repulic of Korea (Korea, Republic of); Heo, Duchang; Kim, Ryun Kyung; Jeon, Seongchae; Seo, Chang-Woo; Kim, Cho Rong [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Repulic of Korea (Korea, Republic of); Ahn, Byung Tae [Department of Materials Science and Engineering, KAIST, Daejeon, Repulic of Korea (Korea, Republic of); Lee, Tae-Bum [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Repulic of Korea (Korea, Republic of)

    2013-12-11

    We introduce polycrystalline cadmium telluride (CdTe) with high atomic number and density, low effective energy and wide band gap for application in large area diagnostic X-ray digital imaging. In this work, polycrystalline CdTe films were fabricated on ITO/glass substrate by both physical vapor deposition (PVD) with slow deposition rate and pressure of 10{sup −6} Torr and the closed space sublimation (CSS) method with high deposition rate and low vacuum pressure(10{sup −2} Torr). The various polycrystalline CdTe films were grown at different deposition rates and substrate temperatures. Physical properties such as microstructures and the crystal structure of the polycrystalline samples were investigated by SEM and XRD patterns respectively. The PVD method resulted in microstructures with columnar shape and more uniform surface, while the CSS method produced microstructures with many larger grains and less uniform surface. The films were polycrystalline structures with a preferential (111) direction. The electrical and optical properties such as the dark current as a function of applied bias voltage and X-ray sensitivity of the fabricated films were measured and investigated under X-ray exposure.

  4. Structural and electrical properties of polycrystalline CdTe films for direct X-ray imaging detectors

    Science.gov (United States)

    Cha, Bo Kyung; Yang, Keedong; Cha, Eun Seok; Yong, Seok-Min; Heo, Duchang; Kim, Ryun Kyung; Jeon, Seongchae; Seo, Chang-Woo; Kim, Cho Rong; Ahn, Byung Tae; Lee, Tae-Bum

    2013-12-01

    We introduce polycrystalline cadmium telluride (CdTe) with high atomic number and density, low effective energy and wide band gap for application in large area diagnostic X-ray digital imaging. In this work, polycrystalline CdTe films were fabricated on ITO/glass substrate by both physical vapor deposition (PVD) with slow deposition rate and pressure of 10-6 Torr and the closed space sublimation (CSS) method with high deposition rate and low vacuum pressure(10-2 Torr). The various polycrystalline CdTe films were grown at different deposition rates and substrate temperatures. Physical properties such as microstructures and the crystal structure of the polycrystalline samples were investigated by SEM and XRD patterns respectively. The PVD method resulted in microstructures with columnar shape and more uniform surface, while the CSS method produced microstructures with many larger grains and less uniform surface. The films were polycrystalline structures with a preferential (111) direction. The electrical and optical properties such as the dark current as a function of applied bias voltage and X-ray sensitivity of the fabricated films were measured and investigated under X-ray exposure.

  5. Gamma ray detector modules

    Science.gov (United States)

    Capote, M. Albert (Inventor); Lenos, Howard A. (Inventor)

    2009-01-01

    A radiation detector assembly has a semiconductor detector array substrate of CdZnTe or CdTe, having a plurality of detector cell pads on a first surface thereof, the pads having a contact metallization and a solder barrier metallization. An interposer card has planar dimensions no larger than planar dimensions of the semiconductor detector array substrate, a plurality of interconnect pads on a first surface thereof, at least one readout semiconductor chip and at least one connector on a second surface thereof, each having planar dimensions no larger than the planar dimensions of the interposer card. Solder columns extend from contacts on the interposer first surface to the plurality of pads on the semiconductor detector array substrate first surface, the solder columns having at least one solder having a melting point or liquidus less than 120 degrees C. An encapsulant is disposed between the interposer circuit card first surface and the semiconductor detector array substrate first surface, encapsulating the solder columns, the encapsulant curing at a temperature no greater than 120 degrees C.

  6. Fine-pitch semiconductor detector for the FOXSI mission

    CERN Document Server

    Ishikawa, Shin-nosuke; Tajima, Hiroyasu; Tanaka, Takaaki; Watanabe, Shin; Odaka, Hirokazu; Fukuyama, Taro; Kokubun, Motohide; Takahashi, Tadayuki; Terada, Yukikatsu; Krucker, Sam; Christe, Steven; McBride, Steve; Glesener, Lindsay

    2015-01-01

    The Focusing Optics X-ray Solar Imager (FOXSI) is a NASA sounding rocket mission which will study particle acceleration and coronal heating on the Sun through high sensitivity observations in the hard X-ray energy band (5-15 keV). Combining high-resolution focusing X-ray optics and fine-pitch imaging sensors, FOXSI will achieve superior sensitivity; two orders of magnitude better than that of the RHESSI satellite. As the focal plane detector, a Double-sided Si Strip Detector (DSSD) with a front-end ASIC (Application Specific Integrated Circuit) will fulfill the scientific requirements of spatial and energy resolution, low energy threshold and time resolution. We have designed and fabricated a DSSD with a thickness of 500 {\\mu}m and a dimension of 9.6 mm x 9.6 mm, containing 128 strips with a pitch of 75 {\\mu}m, which corresponds to 8 arcsec at the focal length of 2 m. We also developed a low-noise ASIC specified to FOXSI. The detector was successfully operated in the laboratory at a temperature of -20 C and w...

  7. Characterization of CdTe sensors with Schottky contacts coupled to charge-integrating pixel array detectors for X-ray science

    Science.gov (United States)

    Becker, J.; Tate, M. W.; Shanks, K. S.; Philipp, H. T.; Weiss, J. T.; Purohit, P.; Chamberlain, D.; Ruff, J. P. C.; Gruner, S. M.

    2016-12-01

    Pixel Array Detectors (PADs) consist of an x-ray sensor layer bonded pixel-by-pixel to an underlying readout chip. This approach allows both the sensor and the custom pixel electronics to be tailored independently to best match the x-ray imaging requirements. Here we present characterizations of CdTe sensors hybridized with two different charge-integrating readout chips, the Keck PAD and the Mixed-Mode PAD (MM-PAD), both developed previously in our laboratory. The charge-integrating architecture of each of these PADs extends the instantaneous counting rate by many orders of magnitude beyond that obtainable with photon counting architectures. The Keck PAD chip consists of rapid, 8-frame, in-pixel storage elements with framing periods detector, the MM-PAD, has an extended dynamic range by utilizing an in-pixel overflow counter coupled with charge removal circuitry activated at each overflow. This allows the recording of signals from the single-photon level to tens of millions of x-rays/pixel/frame while framing at 1 kHz. Both detector chips consist of a 128 × 128 pixel array with (150 μm)2 pixels.

  8. Lattice location and local magnetism of recoil implanted Fe impurities in wide and narrow band semiconductors CdTe, CdSe, and InSb: Experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Mohanta, S. K.; Mishra, S. N. [Tata Institute of Fundamental Research (TIFR), Homi Bhabha Road, Mumbai 400005 (India)

    2014-05-07

    Employing the time differential perturbed angular distribution method, we have measured local susceptibility and spin relaxation rate of {sup 54}Fe nuclei implanted in III-V and II-VI semiconductors, CdTe, CdSe, and InSb. The magnetic response of Fe, identified to occupy the metal as well as the semi-metal atom sites, exhibit Curie-Weiss type susceptibility and Korringa like spin relaxation rate, revealing the existence of localized moments with small spin fluctuation temperature. The experimental results are supported by first principle electronic structure calculations performed within the frame work of density functional theory.

  9. X-ray measurement with Pin type semiconductor detectors; Medicion de rayos X con detectores de semiconductor tipo PIN

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez J, F.J. [Instituto Nacional de Investigaciones Nucleares, Departamento de Electronica, C.P. 52045 Salazar, Estado de Mexico (Mexico)

    2000-07-01

    Here are presented the experimental results of the applications of Pin type radiation detectors developed in a National Institute of Nuclear Research (ININ) project, in the measurement of low energy gamma and X-rays. The applications were oriented mainly toward the Medical Physics area. It is planned other applications which are in process of implementation inside the National Institute of Nuclear Research in Mexico. (Author)

  10. The simulation of charge sharing in semiconductor X-ray pixel detectors

    CERN Document Server

    Mathieson, K; O'Shea, V; Passmore, M S; Rahman, M; Smith, K M; Watt, J; Whitehill, C

    2002-01-01

    Two simulation packages were used to model the sharing of charge, due to the scattering and diffusion of carriers, between adjacent pixel elements in semiconductors X-ray detectors. The X-ray interaction and the consequent multiple scattering was modelled with the aid of the Monte Carlo package, MCNP. The resultant deposited charge distribution was then used to create the charge cloud profile in the finite element semiconductor simulation code MEDICI. The analysis of the current pulses induced on pixel electrodes for varying photon energies was performed for a GaAs pixel detector. For a pixel pitch of 25 mu m, the charge lost to a neighbouring pixel was observed to be constant, at 0.6%, through the energies simulated. Ultimately, a fundamental limit on the pixel element size for imaging and spectroscopic devices may be set due to these key physical principles.

  11. Analysis of defect formation in semiconductor cryogenic bolometric detectors created by heavy dark matter

    CERN Document Server

    Lazanu, Ionel; Lazanu, Sorina

    2012-01-01

    The cryogenic detectors in the form of bolometers are presently used for different applications, in particular for very rare or hypothetical events associated with new forms of matter, specifically related to the existence of Dark Matter. In the detection of particles with a semiconductor as target and detector, usually two signals are measured: ionization and heat. The amplification of the thermal signal is obtained with the prescriptions from Luke-Neganov effect. The energy deposited in the semiconductor lattice as stable defects in the form of Frenkel pairs at cryogenic temperatures, following the interaction of a dark matter particle, is evaluated and consequences for measured quantities are discussed. This contribution is included in the energy balance of the Luke effect. Applying the present model to germanium and silicon, we found that for the same incident weakly interacting massive particle the energy deposited in defects in germanium is about twice the value for silicon.

  12. Investigation of efficient termination structure for improved breakdown properties of semiconductor radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Krizaj, D.; Resnik, D.; Vrtacnik, D.; Amon, S. [Univ. of Ljubljana (Slovenia). Faculty of Electrical Engineering; Cindro, V. [Jozef Stefan Inst., Ljubljana (Slovenia)

    1998-06-01

    Efficiency of a new junction termination structure for improvement of breakdown properties of semiconductor radiation detectors is investigated. The structure consists of a diffused resistor winding around the active junction in a spiral fashion. The current flow through the spiral enables controlled potential distribution along the spiral turns and thus controlled depletion spreading from the main junction, efficiently preventing premature avalanche breakdown. Both multiple guard-ring structures and spiral junction termination structures have shown good breakdown properties typically three to five times higher than breakdown voltages of diodes without junction termination. The breakdown voltages of spiral junction termination structures are only weakly influenced by changes in substrate doping concentration caused by neutron irradiation. They can thus be considered for termination of future semiconductor radiation detectors.

  13. Development of radiation tolerant semiconductor detectors for the Super-LHC

    CERN Document Server

    Moll, M; Al-Ajili, A A; Alfieri, G; Allport, P P; Artuso, M; Assouak, S; Avset, B S; Barabash, L; Barcz, A; Bates, R; Biagi, S F; Bilei, G M; Bisello, D; Blue, A; Blumenau, A; Boisvert, V; Bölla, G; Bondarenko, G B; Borchi, E; Borrello, L; Bortoletto, D; Boscardin, M; Bosisio, L; Bowcock, T J V; Brodbeck, T J; Broz, J; Bruzzi, M; Brzozowski, A; Buda, M; Buhmann, P; Buttar, C; Campabadal, F; Campbell, D; Candelori, A; Casse, G; Cavallini, A; Charron, S; Chilingarov, A; Chren, D; Cindro, V; Collins, P; Coluccia, R; Contarato, D; Coutinho, J; Creanza, D; Cunningham, W; Betta, G F D; Dawson, I; de Boer, Wim; De Palma, M; Demina, R; Dervan, P; Dittongo, S; Dolezal, Z; Dolgolenko, A; Eberlein, T; Eremin, V; Fall, C; Fasolo, F; Fizzotti, F; Fleta, C; Focardi, E; Forton, E; Fretwurst, E; García, C; García-Navarro, J E; Gaubas, E; Genest, M H; Gill, K A; Giolo, K; Glaser, M; Gössling, C; Golovine, V; Sevilla, S G; Gorelov, I; Goss, J; Bates, A G; Grégoire, G; Gregori, P; Grigoriev, E; Grillo, A A; Groza, A; Guskov, J; Haddad, L; Härkönen, J; Hauler, F; Hoeferkamp, M; Honniger, F; Horazdovsky, T; Horisberger, Roland Paul; Horn, M; Houdayer, A; Hourahine, B; Hughes, G; Ilyashenko, Yu S; Irmscher, K; Ivanov, A; Jarasiunas, K; Johansen, K M H; Jones, B K; Jones, R; Joram, C; Jungermann, L; Kalinina, E; Kaminski, P; Karpenko, A; Karpov, A; Kazlauskiene, V; Kazukauskas, V; Khivrich, V; Khomenkov, V; Kierstead, J A; Klaiber Lodewigs, J; Klingenberg, R; Kodys, P; Kohout, Z; Korjenevski, S; Koski, M; Kozlowski, R; Kozodaev, M; Kramberger, G; Krasel, O; Kuznetsov, A; Kwan, S; Lagomarsino, S; Lassila-Perini, K M; Lastovetsky, V F; Latino, G; Lazanu, S; Lazanu, I; Lebedev, A; Lebel, C; Leinonen, K; Leroy, C; Li Z; Lindström, G; Linhart, V; Litovchenko, A P; Litovchenko, P G; Lo Giudice, A; Lozano, M; Luczynski, Z; Luukka, P; Macchiolo, A; Makarenko, L F; Mandic, I; Manfredotti, C; Manna, N; Garcia, S Mi; Marunko, S; Mathieson, K; Melone, J; Menichelli, D; Messineo, A; Metcalfe, J; Miglio, S; Mikuz, M; Miyamoto, J; Monakhov, E; Moscatelli, F; Naoumov, D; Nossarzhevska, E; Nysten, J; Olivero, P; OShea, V; Palviainen, T; Paolini, C; Parkes, C; Passeri, D; Pein, U; Pellegrini, G; Perera, L; Petasecca, M; Piemonte, C; Pignatel, G U; Pinho, N; Pintilie, I; Pintilie, L; Polivtsev, L; Polozov, P; Popa, A; Popule, J; Pospísil, S; Pozza, A; Radicci, V; Rafí, J M; Rando, R; Röder, R; Rohe, T; Ronchin, S; Rott, C; Roy, A; Ruzin, A; Sadrozinski, H F W; Sakalauskas, S; Scaringella, M; Schiavulli, L; Schnetzer, S; Schumm, B; Sciortino, S; Scorzoni, A; Segneri, G; Seidel, S; Seiden, A; Sellberg, G; Sellin, P J; Sentenac, D; Shipsey, I; Sícho, P; Sloan, T; Solar, M; Son, S; Sopko, B; Sopko, V; Spencer, N; Stahl, J; Stolze, D; Stone, R; Storasta, J; Strokan, N; Sudzius, M; Surma, B; Suvorov, A; Svensson, B G; Tipton, P; Tomasek, M; Tsvetkov, A; Tuominen, E; Tuovinen, E; Tuuva, T; Tylchin, M; Uebersee, H; Uher, J; Ullán, M; Vaitkus, J V; Velthuis, J; Verbitskaya, E; Vrba, V; Wagner, G; Wilhelm, I; Worm, S; Wright, V; Wunstorf, R; Yiuri, Y; Zabierowski, P; Zaluzhny, A; Zavrtanik, M; Zen, M; Zhukov, V; Zorzi, N

    2005-01-01

    The envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 10challenges for the tracking detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10ns as well as the need for cost effective detectors have called for an intensive R&D program. The CERN RD50 collaboration "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" is working on the development of semiconductor sensors matching the requirements of the SLHC. Sensors based on defect engineered silicon like Czochralski, epitaxial and oxygen enriched silicon have been developed. With 3D, Semi-3D and thin detectors new detector concepts have been evaluated and a study on the use of standard and oxygen enriched p-type silicon detectors revealed a promising approach for radiation tolerant cost effective devices. These and other most recent advancements of the RD50 ...

  14. Recent advancements in the development of radiation hard semiconductor detectors for S-LHC

    CERN Document Server

    Fretwurst, E; Al-Ajili, A A; Alfieri, G; Allport, P P; Artuso, M; Assouak, S; Avset, B S; Barabash, L; Barcz, A; Bates, R; Biagi, S F; Bilei, G M; Bisello, D; Blue, A; Blumenau, A; Boisvert, V; Bölla, G; Bondarenko, G B; Borchi, E; Borrello, L; Bortoletto, D; Boscardin, M; Bosisio, L; Bowcock, T J V; Brodbeck, T J; Broz, J; Bruzzi, M; Brzozowski, A; Buda, M; Buhmann, P; Buttar, C; Campabadal, F; Campbell, D; Candelori, A; Casse, G; Cavallini, A; Charron, S; Chilingarov, A G; Chren, D; Cindro, V; Collins, P; Coluccia, R; Contarato, D; Coutinho, J; Creanza, D; Cunningham, L; Dalla Betta, G F; Dawson, I; de Boer, Wim; De Palma, M; Demina, R; Dervan, P; Dittongo, S; Dolezal, Z; Dolgolenko, A; Eberlein, T; Eremin, V; Fall, C; Fasolo, F; Ferbel, T; Fizzotti, F; Fleta, C; Focardi, E; Forton, E; García, C; García-Navarro, J E; Gaubas, E; Genest, M H; Gill, K A; Giolo, K; Glaser, M; Gössling, C; Golovine, V; González-Sevilla, S; Gorelov,I; Goss, J; Gouldwell-Bates, A; Grégoire, G; Gregori, P; Grigoriev, E; Grillo, A A; Groza, A; Guskov, J; Haddad, L; Härkönen, J; Hauler, F; Hoeferkamp, M; Honniger, F; Horazdovsky, T; Horisberger, R P; Horn, M; Houdayer, A; Hourahine, B; Hughes, G; Ilyashenko, Yu S; Irmscher, K; Ivanov, A; Jarasiunas, K; Johansen, K M H; Jones, B K; Jones, R; Joram, C; Jungermann, L; Kalinina, E; Kaminski, P; Karpenko, A; Karpov, A; Kazlauskiene, V; Kazukauskas, V; Khivrich, V; Khomenkov, V P; Kierstead, J A; Klaiber Lodewigs, J M; Klingenberg, R; Kodys, P; Kohout, Z; Korjenevski, S; Koski, M; Kozlowski, R; Kozodaev, M; Kramberger, G; Krasel, O; Kuznetsov, A; Kwan, S; Lagomarsino, S; Lassila-Perini, K M; Lastovetsky, V F; Latino, G; Lazanu, I; Lazanu, S; Lebedev, A; Lebel, C; Leinonen, K; Leroy, C; Li, Z; Lindström, G; Linhart, V; Litovchenko, P G; Litovchenko, A P; Lo Giudice, A; Lozano, M; Luczynski, Z; Luukka, Panja; Macchiolo, A; Makarenko, L F; Mandic, I; Manfredotti, C; Manna, N; Martí i García, S; Marunko, S; Mathieson, K; Melone, J; Menichelli, D; Messineo, A; Metcalfe, J; Miglio, S; Mikuz, M; Miyamoto, J; Moll, M; Monakhov, E; Moscatelli, F; Naoumov, D; Nossarzhevska, E; Nysten, J; Olivero, P; O'Shea, V; Palviainen, T; Paolini, C; Parkes, C; Passeri, D; Pein, U; Pellegrini, G; Perera, L; Petasecca, M; Piemonte, C; Pignatel, G U; Pinho, N; Pintilie, I; Pintilie, L; Polivtsev, L; Polozov, P; Popa, A; Populea, J; Pospísil, S; Pozza, A; Radicci, V; Rafí, J M; Rando, R; Röder, R; Rohe, T; Ronchin, S; Rott, C; Roy, A; Ruzin, A; Sadrozinski, H F W; Sakalauskas, S; Scaringella, M; Schiavulli, L; Schnetzer, S; Schumm, B; Sciortino, S; Scorzoni, A; Segneri, G; Seidela, S; Seiden, A; Sellberg, G; Sellin, P J; Sentenac, D; Shipsey, I; Sícho, P; Sloan, T; Solar, M; Son, S; Sopko, B; Sopko, V; Spencer, N; Stahl, J; Stolze, D; Stone, R; Storasta, J; Strokan, N; Sudzius, M; Surma, B; Suvorov, A; Svensson, B G; Tipton, P; Tomasek, M; Tsvetkov, A; Tuominen, E; Tuovinen, E; Tuuva, T; Tylchin, M; Uebersee, H; Uher, J; Ullán, M; Vaitkus, J V; Velthuis, J; Verbitskaya, E; Vrba, V; Wagner, G; Wilhelm, I; Worm, S; Wright, V; Wunstorf, R; Yiuri, Y; Zabierowski, P; Zaluzhny, A; Zavrtanik, M; Zen, M; Zhukov, V; Zorzi, N

    2005-01-01

    The proposed luminosity upgrade of the Large Hadron Collider (S-LHC) at CERN will demand the innermost layers of the vertex detectors to sustain fluences of about 1016 hadrons/cm2. Due to the high multiplicity of tracks, the required spatial resolution and the extremely harsh radiation field new detector concepts and semiconductor materials have to be explored for a possible solution of this challenge. The CERN RD50 collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” has started in 2002 an R&D program for the development of detector technologies that will fulfill the requirements of the S-LHC. Different strategies are followed by RD50 to improve the radiation tolerance. These include the development of defect engineered silicon like Czochralski, epitaxial and oxygen-enriched silicon and of other semiconductor materials like SiC and GaN as well as extensive studies of the microscopic defects responsible for the degradation of irradiated sensors. Furthe...

  15. 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, and Room Temperature Semiconductor Detectors Workshop

    Science.gov (United States)

    The Nuclear Science Symposium (NSS) offers an outstanding opportunity for scientists and engineers interested or actively working in the fields of nuclear science, radiation instrumentation, software and their applications, to meet and discuss with colleagues from around the world. The program emphasizes the latest developments in technology and instrumentation and their implementation in experiments for space sciences, accelerators, other radiation environments, and homeland security. The Medical Imaging Conference (MIC) is the foremost international scientific meeting on the physics, engineering and mathematical aspects of nuclear medicine based imaging. As the field develops, multi-modality approaches are becoming more and more important. The content of the MIC reflects this, with a growing emphasis on the methodologies of X-ray, optical and MR imaging as they relate to nuclear imaging techniques. In addition, specialized topics will be addressed in the Short Courses and Workshops programs. The Workshop on Room-Temperature Semiconductor Detectors (RTSD) represents the largest forum of scientists and engineers developing new semiconductor radiation detectors and imaging arrays. Room-temperature solid-state radiation detectors for X-ray, gamma-ray, and neutron radiation are finding increasing applications in such diverse fields as medicine, homeland security, astrophysics and environmental remediation. The objective of this workshop is to provide a forum for discussion of the state of the art of material development for semiconductor, scintillator, and organic materials for detection, materials characterization, device fabrication and technology, electronics and applications.

  16. Wiring-up carbon single wall nanotubes to polycrystalline inorganic semiconductor thin films: low-barrier, copper-free back contact to CdTe solar cells.

    Science.gov (United States)

    Phillips, Adam B; Khanal, Rajendra R; Song, Zhaoning; Zartman, Rosa M; DeWitt, Jonathan L; Stone, Jon M; Roland, Paul J; Plotnikov, Victor V; Carter, Chad W; Stayancho, John M; Ellingson, Randall J; Compaan, Alvin D; Heben, Michael J

    2013-11-13

    We have discovered that films of carbon single wall nanotubes (SWNTs) make excellent back contacts to CdTe devices without any modification to the CdTe surface. Efficiencies of SWNT-contacted devices are slightly higher than otherwise identical devices formed with standard Au/Cu back contacts. The SWNT layer is thermally stable and easily applied with a spray process, and SWNT-contacted devices show no signs of degradation during accelerated life testing.

  17. Toward VIP-PIX: A Low Noise Readout ASIC for Pixelated CdTe Gamma-Ray Detectors for Use in the Next Generation of PET Scanners.

    Science.gov (United States)

    Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Puigdengoles, Carles; Lorenzo, Gianluca De; Martínez, Ricardo

    2013-08-01

    VIP-PIX will be a low noise and low power pixel readout electronics with digital output for pixelated Cadmium Telluride (CdTe) detectors. The proposed pixel will be part of a 2D pixel-array detector for various types of nuclear medicine imaging devices such as positron-emission tomography (PET) scanners, Compton gamma cameras, and positron-emission mammography (PEM) scanners. Each pixel will include a SAR ADC that provides the energy deposited with 10-bit resolution. Simultaneously, the self-triggered pixel which will be connected to a global time-to-digital converter (TDC) with 1 ns resolution will provide the event's time stamp. The analog part of the readout chain and the ADC have been fabricated with TSMC 0.25 μm mixed-signal CMOS technology and characterized with an external test pulse. The power consumption of these parts is 200 μW from a 2.5 V supply. It offers 4 switchable gains from ±10 mV/fC to ±40 mV/fC and an input charge dynamic range of up to ±70 fC for the minimum gain for both polarities. Based on noise measurements, the expected equivalent noise charge (ENC) is 65 e(-) RMS at room temperature.

  18. Characterization of CdTe Sensors with Schottky Contacts Coupled to Charge-Integrating Pixel Array Detectors for X-Ray Science

    CERN Document Server

    Becker, Julian; Shanks, Katherine S; Philipp, Hugh T; Weiss, Joel T; Purohit, Prafull; Chamberlain, Darol; Ruff, Jacob P C; Gruner, Sol M

    2016-01-01

    Pixel Array Detectors (PADs) consist of an x-ray sensor layer bonded pixel-by-pixel to an underlying readout chip. This approach allows both the sensor and the custom pixel electronics to be tailored independently to best match the x-ray imaging requirements. Here we present characterizations of CdTe sensors hybridized with two different charge-integrating readout chips, the Keck PAD and the Mixed-Mode PAD (MM-PAD), both developed previously in our laboratory. The charge-integrating architecture of each of these PADs extends the instantaneous counting rate by many orders of magnitude beyond that obtainable with photon counting architectures. The Keck PAD chip consists of rapid, 8-frame, in-pixel storage elements with framing periods $<$150 ns. The second detector, the MM-PAD, has an extended dynamic range by utilizing an in-pixel overflow counter coupled with charge removal circuitry activated at each overflow. This allows the recording of signals from the single-photon level to tens of millions of x-rays/...

  19. Detection of fast neutrons from shielded nuclear materials using a semiconductor alpha detector.

    Science.gov (United States)

    Pöllänen, R; Siiskonen, T

    2014-08-01

    The response of a semiconductor alpha detector to fast (>1 MeV) neutrons was investigated by using measurements and simulations. A polyethylene converter was placed in front of the detector to register recoil protons generated by elastic collisions between neutrons and hydrogen nuclei of the converter. The developed prototype equipment was tested with shielded radiation sources. The low background of the detector and insensitivity to high-energy gamma rays above 1 MeV are advantages when the detection of neutron-emitting nuclear materials is of importance. In the case of a (252)Cf neutron spectrum, the intrinsic efficiency of fast neutron detection was determined to be 2.5×10(-4), whereas three-fold greater efficiency was obtained for a (241)AmBe neutron spectrum.

  20. Developing fine-pixel CdTe detectors for the next generation of high-resolution hard x-ray telescopes

    Science.gov (United States)

    Christe, Steven

    Over the past decade, the NASA Marshall Space Flight Center (MSFC) has been improving the angular resolution of hard X-ray (HXR; 20 "70 keV) optics to the point that we now routinely manufacture optics modules with an angular resolution of 20 arcsec Half Power Diameter (HDP), almost three times the performance of NuSTAR optics (Ramsey et al. 2013; Gubarev et al. 2013a; Atkins et al. 2013). New techniques are currently being developed to provide even higher angular resolution. High angular resolution HXR optics require detectors with a large number of fine pixels in order to adequately sample the telescope point spread function (PSF) over the entire field of view. Excessively over-sampling the PSF will increase readout noise and require more processing with no appreciable increase in image quality. An appropriate level of over-sampling is to have 3 pixels within the HPD. For the HERO mirrors, where the HPD is 26 arcsec over a 6-m focal length converts to 750 μm, the optimum pixel size is around 250 μm. At a 10-m focal length these detectors can support a 16 arcsec HPD. Of course, the detectors must also have high efficiency in the HXR region, good energy resolution, low background, low power requirements, and low sensitivity to radiation damage (Ramsey 2001). The ability to handle high counting rates is also desirable for efficient calibration. A collaboration between Goddard Space Flight Center (GSFC), MSFC, and Rutherford Appleton Laboratory (RAL) in the UK is developing precisely such detectors under an ongoing, funded APRA program (FY2015 to FY2017). The detectors use the RALdeveloped Application Specific Integrated Circuit (ASIC) dubbed HEXITEC, for High Energy X-Ray Imaging Technology. These HEXITEC ASICs can be bonded to 1- or 2- mm-thick Cadmium Telluride (CdTe) or Cadmium-Zinc-Telluride (CZT) to create a fine (250 μm pitch) HXR detector (Jones et al. 2009; Seller et al. 2011). The objectives of this funded effort are to develop and test a HEXITEC

  1. Extensive simulation studies on the reconstructed image resolution of a position sensitive detector based on pixelated CdTe crystals

    CERN Document Server

    Zachariadou, K; Kaissas, I; Seferlis, S; Lambropoulos, C; Loukas, D; Potiriadis, C

    2011-01-01

    We present results on the reconstructed image resolution of a position sensitive radiation instrument (COCAE) based on extensive simulation studies. The reconstructed image resolution has been investigated in a wide range of incident photon energies emitted by point-like sources located at different source-to-detector distances on and off the detector's symmetry axis. The ability of the detector to distinguish multiple radioactive sources observed simultaneously is investigating by simulating point-like sources of different energies located on and off the detector's symmetry axis and at different positions

  2. Response function of semiconductor detectors, Ge and Si(Li); Funcao resposta de detectores semicondutores, Ge e Si(Li)

    Energy Technology Data Exchange (ETDEWEB)

    Zevallos Chavez, Juan Yury

    2003-07-01

    The Response Function (RF) for Ge and Si(Li) semiconductor detectors was obtained. The RF was calculated for five detectors, four Hp Ge with active volumes of 89 cm{sup 3} , 50 cm{sup 3} , 8 cm{sup 3} and 5 cm{sup 3}, and one Si(Li) with 0.143 cm{sup 3} of active volume. The interval of energy studied ranged from 6 keV up to 1.5 MeV. Two kinds of studies were done in this work. The first one was the RF dependence with the detection geometry. Here the calculation of the RF for a geometry named as simple and an extrapolation of that RF, were both done. The extrapolation process analyzed both, spectra obtained with a shielding geometry and spectra where the source-detector distance was modified. The second one was the RF dependence with the detection electronics. This study was done varying the shaping time of the pulse in the detection electronics. The purpose was to verify the effect of the ballistic deficit in the resolution of the detector. This effect was not observed. The RF components that describe the region of the total absorption of the energy of the incident photons, and the partial absorption of this energy, were both treated. In particular, empirical functions were proposed for the treatment of both, the multiple scattering originated in the detector (crystal), and the photon scattering originated in materials of the neighborhood of the crystal. Another study involving Monte Carlo simulations was also done in order to comprehend the photon scattering structures produced in an iron shield. A deconvolution method is suggested, for spectra related to scattered radiation in order to assess the dose delivered to the scatterer. (author)

  3. 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

  4. Perfluorocarbons and their use in Cooling Systems for Semiconductor Particle Detectors

    CERN Document Server

    Vacek, V; Ilie, S; Lindsay, S

    2000-01-01

    We report on the development of evaporative fluorocarbon cooling for the semiconductor pixel and micro-strip sensors of inner tracking detector of the ATLAS experiment at the future CERN Large Hadron Collider (LHC). We proceeded with studies using perfluoro-n-propane (3M-"PFG 5030"; C3F8), perfluoro-n-butane (3M-"PFG 5040"; C4F10), trifluoro-iodo-methane (CF3I) and custom C3F8/C4F10 mixtures. Certain thermo-physical properties had to be verified for these fluids.

  5. Measurements of Ultra-Fast single photon counting chip with energy window and 75 μm pixel pitch with Si and CdTe detectors

    Science.gov (United States)

    Maj, P.; Grybos, P.; Kasinski, K.; Koziol, A.; Krzyzanowska, A.; Kmon, P.; Szczygiel, R.; Zoladz, M.

    2017-03-01

    Single photon counting pixel detectors become increasingly popular in various 2-D X-ray imaging techniques and scientific experiments mainly in solid state physics, material science and medicine. This paper presents architecture and measurement results of the UFXC32k chip designed in a CMOS 130 nm process. The chip consists of about 50 million transistors and has an area of 9.64 mm × 20.15 mm. The core of the IC is a matrix of 128 × 256 pixels of 75 μm pitch. Each pixel contains a CSA, a shaper with tunable gain, two discriminators with correction circuits and two 14-bit ripple counters operating in a normal mode (with energy window), a long counter mode (one 28-bit counter) and a zero-dead time mode. Gain and noise performance were verified with X-ray radiation and with the chip connected to Si (320 μm thick) and CdTe (750 μ m thick) sensors.

  6. MediSPECT: Single photon emission computed tomography system for small field of view small animal imaging based on a CdTe hybrid pixel detector

    Science.gov (United States)

    Accorsi, R.; Autiero, M.; Celentano, L.; Chmeissani, M.; Cozzolino, R.; Curion, A. S.; Frallicciardi, P.; Laccetti, P.; Lanza, R. C.; Lauria, A.; Maiorino, M.; Marotta, M.; Mettivier, G.; Montesi, M. C.; Riccio, P.; Roberti, G.; Russo, P.

    2007-02-01

    We describe MediSPECT, a new scanner developed at University and INFN Napoli, for SPECT studies on small animals with a small field of view (FOV) and high spatial resolution. The CdTe pixel detector (a 256×256 matrix of 55 μm square pixels) operating in single photon counting for detection of gamma-rays with low and medium energy (e.g. 125I, 27-35 keV, 99mTc, 140 keV), is bump bonded to the Medipix2 readout chip. The FOV of the MediSPECT scanner with a coded aperture mask collimator ranges from 6.3 mm (system spatial resolution 110 μm at 27-35 keV) to 24.3 mm. With a 0.30 mm pinhole the FOV ranges from 2.4 to 29 mm (where the system spatial resolution is 1.0 mm at 27-35 keV and 2.0 mm at 140 keV). MediSPECT will be used for in vivo imaging of small organs or tissue structures in mouse, e.g., brain, thyroid, heart or tumor.

  7. Very Low-Power Consumption Analog Pulse Processing ASIC for Semiconductor Radiation Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Wessendorf, K.O.; Lund, J.C.; Brunett, B.A.; Laguna, G.R.; Clements, J.W.

    1999-08-23

    We describe a very-low power consumption circuit for processing the pulses from a semiconductor radiation detector. The circuit was designed for use with a cadmium zinc telluride (CZT) detector for unattended monitoring of stored nuclear materials. The device is intended to be battery powered and operate at low duty-cycles over a long period of time. This system will provide adequate performance for medium resolution gamma-ray pulse-height spectroscopy applications. The circuit incorporates the functions of a charge sensitive preamplifier, shaping amplifier, and peak sample and hold circuit. An application specific integrated circuit (ASIC) version of the design has been designed, built and tested. With the exception of the input field effect transistor (FET), the circuit is constructed using bipolar components. In this paper the design philosophy and measured performance characteristics of the circuit are described.

  8. Development of a novel 2D position-sensitive semiconductor detector concept

    CERN Document Server

    Bassignana, D; Jaramillo, R; Lozano, M; Munoz, F.J; Pellegrini, G; Quirion, D; Vila, I

    2012-01-01

    A novel 2D position-sensitive semiconductor detector concept has been developed employing resistive electrodes in a single-sided silicon microstrip sensor. The resistive charge division method has been implemented reading out each strip at both ends, in order to get the second coordinate of an ionizing event along the strips length. Two generations of prototypes, with different layout, have been produced and characterized using a pulsed near infra-red laser. The feasibility of the resistive charge division method in silicon microstrip detectors has been demonstrated and the possibility of single-chip readout of the device has been investigated. Experimental data were compared with the theoretical expectations and the electrical simulation of the sensor equivalent circuit coupled to simple electronics readout circuits. The agreement between experimental and simulation results validates the developed simulation as a tool for the optimization of future sensor prototypes.

  9. Characterization of a large CdZnTe coplanar quad-grid semiconductor detector

    CERN Document Server

    Ebert, Joachim; Gehre, Daniel; Hagner, Caren; Heidrich, Nadine; Klingenberg, Rainer; Kröninger, Kevin; Nitsch, Christian; Oldorf, Christian; Quante, Thomas; Rajek, Silke; Rebber, Henning; Rohatsch, Katja; Tebrügge, Jan; Temminghoff, Robert; Theinert, Robert; Timm, Jan; Wonsak, Björn; Zatschler, Stefan; Zuber, Kai

    2015-01-01

    The COBRA collaboration aims to search for neutrinoless double beta-decay of $^{116}$Cd. A demonstrator setup with 64 CdZnTe semiconductor detectors, each with a volume of 1cm$^3$, is currently being operated at the LNGS underground laboratory in Italy. This paper reports on the characterization of a large (2 $\\times$ 2 $\\times$ 1.5)cm$^3$ CdZnTe detector with a new coplanar-grid design for applications in $\\gamma$-ray spectroscopy and low-background operation. Several studies of electric properties as well as of the spectrometric performance, like energy response and resolution, are conducted. Furthermore, measurements including investigating the operational stability and a possibility to identify multiple-scattered photons are presented.

  10. A Monte Carlo simulation study of an improved K-edge log-subtraction X-ray imaging using a photon counting CdTe detector

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngjin, E-mail: radioyoungj@gmail.com [Department of Radiological Science, Eulji University, 553, Sanseong-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do (Korea, Republic of); Lee, Amy Candy [Department of Mathematics and Statistics, McGill University (Canada); Kim, Hee-Joung [Department of Radiological Science and Radiation Convergence Engineering, Yonsei University (Korea, Republic of)

    2016-09-11

    Recently, significant effort has been spent on the development of photons counting detector (PCD) based on a CdTe for applications in X-ray imaging system. The motivation of developing PCDs is higher image quality. Especially, the K-edge subtraction (KES) imaging technique using a PCD is able to improve image quality and useful for increasing the contrast resolution of a target material by utilizing contrast agent. Based on above-mentioned technique, we presented an idea for an improved K-edge log-subtraction (KELS) imaging technique. The KELS imaging technique based on the PCDs can be realized by using different subtraction energy width of the energy window. In this study, the effects of the KELS imaging technique and subtraction energy width of the energy window was investigated with respect to the contrast, standard deviation, and CNR with a Monte Carlo simulation. We simulated the PCD X-ray imaging system based on a CdTe and polymethylmethacrylate (PMMA) phantom which consists of the various iodine contrast agents. To acquired KELS images, images of the phantom using above and below the iodine contrast agent K-edge absorption energy (33.2 keV) have been acquired at different energy range. According to the results, the contrast and standard deviation were decreased, when subtraction energy width of the energy window is increased. Also, the CNR using a KELS imaging technique is higher than that of the images acquired by using whole energy range. Especially, the maximum differences of CNR between whole energy range and KELS images using a 1, 2, and 3 mm diameter iodine contrast agent were acquired 11.33, 8.73, and 8.29 times, respectively. Additionally, the optimum subtraction energy width of the energy window can be acquired at 5, 4, and 3 keV for the 1, 2, and 3 mm diameter iodine contrast agent, respectively. In conclusion, we successfully established an improved KELS imaging technique and optimized subtraction energy width of the energy window, and based on

  11. A Monte Carlo simulation study of an improved K-edge log-subtraction X-ray imaging using a photon counting CdTe detector

    Science.gov (United States)

    Lee, Youngjin; Lee, Amy Candy; Kim, Hee-Joung

    2016-09-01

    Recently, significant effort has been spent on the development of photons counting detector (PCD) based on a CdTe for applications in X-ray imaging system. The motivation of developing PCDs is higher image quality. Especially, the K-edge subtraction (KES) imaging technique using a PCD is able to improve image quality and useful for increasing the contrast resolution of a target material by utilizing contrast agent. Based on above-mentioned technique, we presented an idea for an improved K-edge log-subtraction (KELS) imaging technique. The KELS imaging technique based on the PCDs can be realized by using different subtraction energy width of the energy window. In this study, the effects of the KELS imaging technique and subtraction energy width of the energy window was investigated with respect to the contrast, standard deviation, and CNR with a Monte Carlo simulation. We simulated the PCD X-ray imaging system based on a CdTe and polymethylmethacrylate (PMMA) phantom which consists of the various iodine contrast agents. To acquired KELS images, images of the phantom using above and below the iodine contrast agent K-edge absorption energy (33.2 keV) have been acquired at different energy range. According to the results, the contrast and standard deviation were decreased, when subtraction energy width of the energy window is increased. Also, the CNR using a KELS imaging technique is higher than that of the images acquired by using whole energy range. Especially, the maximum differences of CNR between whole energy range and KELS images using a 1, 2, and 3 mm diameter iodine contrast agent were acquired 11.33, 8.73, and 8.29 times, respectively. Additionally, the optimum subtraction energy width of the energy window can be acquired at 5, 4, and 3 keV for the 1, 2, and 3 mm diameter iodine contrast agent, respectively. In conclusion, we successfully established an improved KELS imaging technique and optimized subtraction energy width of the energy window, and based on

  12. Characterization of CdTe and CdZnTe detectors for gamma-ray imaging applications

    Science.gov (United States)

    Verger, L.; Boitel, M.; Gentet, M. C.; Hamelin, R.; Mestais, C.; Mongellaz, F.; Rustique, J.; Sanchez, G.

    2001-02-01

    CEA-LETI in association with Bicron and Crismatec has been developing solid-state gamma camera technology based on CZT. The project included gamma camera head systems development including front-end electronics with an integrated circuit (ASIC), material growth, and detector fabrication and characterization. One feature of the work is the use of linear correlation between the amplitude and the fast rise time of the signal - which corresponds to the electron transit time in the detector, a development that was reported previously and which allows more than 80% of the 122 keV γ-photons incident on HPBM material to be recovered in a ±6.5% 2D window. In the current work, we summarize other methods to improve CZT detector performance and compare them with the Bi-Parametric Spectrum (BPS) method. The BPS method can also be applied as a diagnositic. BPS curve shapes are shown to vary with electric field, and with electron transport properties, and the correction algorithims are seen to be robust over a range of values. In addition, the technique is found to improve detectors from a variety of sources including some with special electrode geometries. In all cases, the BPS method improves efficiency (>75%) without degrading energy resolution (± 6.5% 2D window) even for a monolithic detector. The method does not overcome bulk inhomogeneity nor noise which comes from low resistivity.

  13. Development and characterization of the lead iodide semiconductor detector; Desenvolvimento e caracterizacao do detector semicondutor de iodeto de chumbo

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Icimone Braga de

    2001-07-01

    A methodology for purification and growth of PbI{sub 2} crystal as well as for its characterization as a room temperature radiation detector was developed in this work. Commercial salts were purified using the zone refining method and, for the purified material growth, the Bridgman method was used. To calculate the purification efficiency, studies of the decrease impurities concentrations were made in the salts and in three sections of the materials purified, using the neutron activation analysis technique. The results showed that the impurities segregate preferentially in the ingot final section. A significant decrease of the impurities concentration in function of the purification pass number was observed. The grown crystals presented good crystalline quality according to the results of the X-ray diffraction analysis. To evaluate the crystal as a semiconductor detector, measurements of dark leakage current, resistivity and the response of ({sup 241}Am) alpha particle and ({sup 241}Am, {sup 57}Co, {sup 133}Ba and {sup 137}Cs) gamma rays were carried out. The radiation response is strongly dependent on the crystals purity. The crystals purified with 500 passes exhibited energy resolution of 10% for {sup 241} Am alpha particle and the gamma rays resolution was compatible with the literature. The photosensibility of the PbI{sub 2} crystal found in the wavelength from 400 to 600 nm range suggests an another application at this crystal as a photodetector to be coupled to scintillators. (author)

  14. Application of GaAs and CdTe photoconductor detectors to X-ray flash radiography

    Energy Technology Data Exchange (ETDEWEB)

    Mathy, F.; Cuzin, M.; Gagelin, J.J.; Mermet, R.; Piaget, B.; Rustique, J.; Verger, L. (CEA, Direction des Technologies Avancees, Lab. d' Electronique, de Technologie et d' Instrumentation, DSYS, 38 - Grenoble (France)); Hauducoeur, A.; Nicolas, P.; Le Dain, L.; Hyvernage, M. (CEA, Direction des Applications Militaires, 77 - Courtry (France))

    1992-11-15

    Some insulating GaAs and CdTe:Cl photoconductor probes were qualified on high energy X-ray single-shot flash generators. The estimated minimum detected dose per flash corresponding to a 230 mrad direct beam attenuated by 200 mm lead was 20 [mu]rad. The dynamic range was about 4 decades in amplitude or charge, with a good linearity. Such detectors, by locating the origin of the parasitic scattered beam, could be used to eliminate this parasitic beam in X-ray flash radiography in detonics experiments. Imaging possibilities are mentioned, as well as X-ray generator monitoring with such detectors or with neutron preirradiated photoconductors. (orig.).

  15. Application of GaAs and CdTe photoconductor detectors to x-ray flash radiography

    Energy Technology Data Exchange (ETDEWEB)

    Mathy, F.; Cuzin, M.; Gagelin, J.J.; Mermet, R.; Piaget, B.; Rustique, J.; Verger, L. [CEA Centre d`Etudes de Grenoble, 38 (FR). Direction des Technologies Avancees; Hauducoeur, A.; Nicolas, P.; Le Dain, L.; Hyvernage, M. [CEA Centre d`Etudes de Vaujours, 77 - Courtry (FR)

    1991-12-31

    Semi-insulating GaAs and CdTe:Cl photoconductor probes were qualified on high energy X ray single shot flash generators. The estimated minimum detected dose per flash corresponding to a 230 mrad direct beam attenuated by 200 mm lead was 20 {mu}rad. The dynamic range was about 4 decades in amplitude or charges, with a good linearity. Such detectors, by locating the origin of the parasitic scattered beam, could be used to eliminate this parasitic beam in X ray flash radiography in detonics experiments. Imaging possibilities are mentioned, as well as X ray generator monitoring with such detectors or with neutron preirradiated photoconductors.

  16. Leakage current measurements on pixelated CdZnTe detectors

    NARCIS (Netherlands)

    Dirks, B.P.F.; Blondel, C.; Daly, F.; Gevin, O.; Limousin, O.; Lugiez, F.

    2006-01-01

    In the field of the R&D of a new generation hard X-ray cameras for space applications we focus on the use of pixelated CdTe or CdZnTe semiconductor detectors. They are covered with 64 (0.9×0.9 mm2) or 256 (0.5×0.5 mm2) pixels, surrounded by a guard ring and operate in the energy ranging from several

  17. Alternative collimator for CdTe (model XR-100T), when it is used for a direct measurements of radiodiagnostic spectra; Colimador alternativo para um detector de CdTe (modelo XR-100T), usado em medidas diretas de espectros de radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Soares, C.; Guevara, M.V. Manso; Milian, F. Mas; Garcia, F., E-mail: mvictoria.mansoguevara@gmail.com [Universidade Estadual de Santa Cruz (CPqCTR/UESC), Ilheus, BA (Brazil). Departamento de Ciencias Exatas; Nieto, L. [Universidade Estadual do Sudoeste da Bahia (UESB), Itapetinga, BA (Brazil)

    2014-01-15

    The spectrum simulation is a powerful instrument of great practical and pedagogical usefulness, because it helps to understand the technical and the instrumental limits of parameters in optimized measurements of magnitudes of interest in physics. Monte Carlo models, based on particle and radiation transport, provide easy and flexible tools for simulating complex geometries and materials. Particularly, MCNPX code is used to compare, manipulate, and quantify simulated and measured spectra. The purpose of this work is to use this tool set to estimate the characteristics of a collimation device, avoiding permanent and temporary damages into the diode-pin detector, during direct measurements of the Bremsstrahlung's spectrum, which was generated from diagnosis tubes with medical purpose. The simulations were made with a maximum voltage of 150 kVp, and typical charges used in radiological protocols in the medical area. Also, differential high pulse spectra, simulated and measured with a CdTe Detector, are reported. (author)

  18. Fast front-end electronics for semiconductor tracking detectors: Trends and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Rivetti, Angelo

    2014-11-21

    In the past few years, extensive research efforts pursued by both the industry and the academia have lead to major improvements in the performance of Analog to Digital Converters (ADCs) and Time to Digital Converters (TDCs). ADCs achieving 8–10 bit resolution, 50–100 MHz conversion frequency and less than 1 mW power consumption are the today's standard, while TDCs have reached sub-picosecond time resolution. These results have been made possible by architectural upgrades combined with the use of ultra deep submicron CMOS technologies with minimum feature size of 130 nm or smaller. Front-end ASICs in which a prompt digitization is followed by signal conditioning in the digital domain can now be envisaged also within the tight power budget typically available in high density tracking systems. Furthermore, tracking detectors embedding high resolution timing capabilities are gaining interest. In the paper, ADC's and TDC's developments which are of particular relevance for the design front-end electronics for semiconductor trackers are discussed along with the benefits and challenges of exploiting such high performance building blocks in implementing the next generation of ASICs for high granularity particle detectors.

  19. Fast front-end electronics for semiconductor tracking detectors: Trends and perspectives

    Science.gov (United States)

    Rivetti, Angelo

    2014-11-01

    In the past few years, extensive research efforts pursued by both the industry and the academia have lead to major improvements in the performance of Analog to Digital Converters (ADCs) and Time to Digital Converters (TDCs). ADCs achieving 8-10 bit resolution, 50-100 MHz conversion frequency and less than 1 mW power consumption are the today's standard, while TDCs have reached sub-picosecond time resolution. These results have been made possible by architectural upgrades combined with the use of ultra deep submicron CMOS technologies with minimum feature size of 130 nm or smaller. Front-end ASICs in which a prompt digitization is followed by signal conditioning in the digital domain can now be envisaged also within the tight power budget typically available in high density tracking systems. Furthermore, tracking detectors embedding high resolution timing capabilities are gaining interest. In the paper, ADC's and TDC's developments which are of particular relevance for the design front-end electronics for semiconductor trackers are discussed along with the benefits and challenges of exploiting such high performance building blocks in implementing the next generation of ASICs for high granularity particle detectors.

  20. Thin film cadmium telluride charged particle sensors for large area neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, J. W.; Smith, L.; Calkins, J.; Mejia, I.; Cantley, K. D.; Chapman, R. A.; Quevedo-Lopez, M.; Gnade, B., E-mail: gnade@utdallas.edu [Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080 (United States); Kunnen, G. R.; Allee, D. R. [Flexible Display Center, Arizona State University, Phoenix, Arizona 85284 (United States); Sastré-Hernández, J.; Contreras-Puente, G. [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Mexico City 07738 (Mexico); Mendoza-Pérez, R. [Universidad Autónoma de la Ciudad de México, Mexico City 09790 (Mexico)

    2014-09-15

    Thin film semiconductor neutron detectors are an attractive candidate to replace {sup 3}He neutron detectors, due to the possibility of low cost manufacturing and the potential for large areas. Polycrystalline CdTe is found to be an excellent material for thin film charged particle detectors—an integral component of a thin film neutron detector. The devices presented here are characterized in terms of their response to alpha and gamma radiation. Individual alpha particles are detected with an intrinsic efficiency of >80%, while the devices are largely insensitive to gamma rays, which is desirable so that the detector does not give false positive counts from gamma rays. The capacitance-voltage behavior of the devices is studied and correlated to the response due to alpha radiation. When coupled with a boron-based neutron converting material, the CdTe detectors are capable of detecting thermal neutrons.

  1. Re-evaluation of Galileo Energetic Particle Detector data - a correction model and comparison to semiconductor detector dead-layer sensitivity losses using SRIM

    Science.gov (United States)

    Lee-Payne, Zoe Hannah

    2016-10-01

    The Energetic Particle Detector launched in 1989 on the Galileo satellite took data on the Jovian Particle environment for 8 years before its demise. Over the course of the mission the detectors in the Composition Measurement System (CMS) have visibly decayed with higher mass particles, specifically oxygen and sulphur, reading far lower energies at later epochs. By considering the non-steady accumulation of damage in the detector, as well as the operation of the priority channel data recording system in place on the EPD, an evolving correction can be made. The recalibration significance can be validated using a model of dead layer build-up in semiconductor detectors, based on SRIM results. The final aim is to assign an estimation dead-layer depth during the mission data recordings.

  2. X and {gamma}-Ray imaging CdTe/CdZnTe detectors. From material to imaging; Imagerie X et {gamma}. Detecteurs CdTe/CdZnTe. Du materiau a l'imageur

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-07-01

    This document presents the recent advances made by the Laboratory of electronics and computer science technologies (Leti) of the French atomic energy commission (CEA) in the domain of semiconductor detectors for X- and {gamma}-ray imaging systems. The new generation of detectors is based on the use of cadmium telluride CdTe or its compound CdZnTe, in association with integrated read-out electronics. The advantages of direct conversion for X-ray and {gamma}-ray detectors and the choice of CdTe is presented first. Then some applications of the CdTe detector are presented: high-energy X-ray tomograph for the control of radioactive waste drums, high definition X-ray imager for medical applications, high-energy X-ray imager for military simulation programs, {gamma}-ray imager for astrophysics applications, and a medical gamma camera to replace the standard Anger camera used in nuclear medicine. (J.S.)

  3. High-efficiency microstructured semiconductor neutron detectors for direct {sup 3}He replacement

    Energy Technology Data Exchange (ETDEWEB)

    Fronk, R.G., E-mail: rfronk@ksu.edu [S.M.A.R.T. Laboratory, Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States); Bellinger, S.L.; Henson, L.C. [S.M.A.R.T. Laboratory, Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States); Huddleston, D.E. [Electronics Design Laboratory, Kansas State University, Manhattan, KS 66506 (United States); Ochs, T.R. [S.M.A.R.T. Laboratory, Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States); Sobering, T.J. [Electronics Design Laboratory, Kansas State University, Manhattan, KS 66506 (United States); McGregor, D.S. [S.M.A.R.T. Laboratory, Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506 (United States)

    2015-04-11

    High-efficiency Microstructured Semiconductor Neutron Detectors (MSNDs) have been tiled and arranged in a cylindrical form factor in order to serve as a direct replacement to aging and increasingly expensive {sup 3}He gas-filled proportional neutron detectors. Two 6-in long by 2-in diameter cylinders were constructed and populated with MSNDs which were then directly compared to a 4 atm Reuter Stokes {sup 3}He detector of the same dimensions. The Generation 1 MSND-based {sup 3}Helium-Replacement (HeRep Mk I) device contained sixty-four 1-cm{sup 2} active-area MSNDs, each with an intrinsic neutron detection efficiency of approximately 7%. A Generation 2 device (the HeRep Mk II) was populated with thirty 4-cm{sup 2} active-area MSNDs, with an intrinsic thermal neutron detection efficiency of approximately 30%. The MSNDs of each HeRep were integrated to count as a single device. The {sup 3}He proportional counter and the HeRep devices were tested while encased in a cylinder of high-density polyethylene measuring a total of 6-in by 9-in. The {sup 3}He counter and the HeRep Mk II were each placed 1 m from a 54-ng {sup 252}Cf source and tested for efficiency. The {sup 3}He proportional counter had a net count rate of 17.13±0.10 cps at 1 m. The HeRep Mk II device had a net count rate of 17.60±0.10 cps, amounting to 102.71±2.65% of the {sup 3}He gas counter while inside of the moderator. Outside of moderator, the {sup 3}He tube had a count rate of 3.35±0.05 cps and the HeRep Mk II device reported 3.19±05, amounting to 95.15±9.04% of the {sup 3}He neutron detector.

  4. Development of neutron/gamma generators and a polymer semiconductor detector for homeland security applications

    Science.gov (United States)

    King, Michael Joseph

    -energetic gamma generators that operate at low-acceleration energies and leverage neutron generator technologies. The dissertation focused on the experimental characterization of the generator performance and involved MCNPX simulations to evaluate and analyze the experimental results. The emission of the 11.7 MeV gamma-rays was observed to be slightly anisotropic and the gamma yield was measured to be 2.0*105 gamma/s-mA. The lanthanum hexaboride target suffered beam damage from a high power density beam; however, this may be overcome by sweeping the beam across a larger target area. The efficient detection of fast neutrons is vital to active interrogation techniques for the detection of both SNM and explosives. Novel organic semiconductors are air-stable, low-cost materials that demonstrate direct electronic particle detection. As part of the development of a pi-conjugated organic polymer for fast neutron detection, charge generation and collection properties were investigated. By devising a dual, thin-film detector test arrangement, charge collection was measured for high energy protons traversing the dual detector arrangement that allowed the creation of variable track lengths by tilting the detector. The results demonstrated that an increase in track length resulted in a decreased signal collection. This can be understood by assuming charge carrier transport along the track instead of along the field lines, which was made possible by the filling of traps. However, this charge collection mechanism may be insufficient to generate a useful signal. This dissertation has explored the viability of a new generation of radiation sources and detectors, where the newly developed ion source technologies and prototype generators will further enhance the capabilities of existing threat detection systems and promote the development of cutting-edge detection technologies.

  5. CdTe and related compounds: physics, defects, hetero- and nano-structures, crystal growth, surfaces and applications

    CERN Document Server

    Triboulet, Robert

    Almost thirty years after the remarkable monograph of K. Zanio and the numerous conferences and articles dedicated since that time to CdTe and CdZnTe, after all the significant progresses in that field and the increasing interest in these materials for several extremely attractive industrial applications, such as nuclear detectors and solar cells, the edition of a new enriched and updated monograph dedicated to these two very topical II-VI semiconductor compounds, covering all their most prominent, modern and fundamental aspects, seemed very relevant and useful.

  6. Monte Carlo simulation of semiconductor detector response to (222)Rn and (220)Rn environments.

    Science.gov (United States)

    Irlinger, J; Trinkl, S; Wielunksi, M; Tschiersch, J; Rühm, W

    2016-07-01

    A new electronic radon/thoron monitor employing semiconductor detectors based on a passive diffusion chamber design has been recently developed at the Helmholtz Zentrum München (HMGU). This device allows for acquisition of alpha particle energy spectra, in order to distinguish alpha particles originating from radon and radon progeny decays, as well as those originating from thoron and its progeny decays. A Monte-Carlo application is described which uses the Geant4 toolkit to simulate these alpha particle spectra. Reasonable agreement between measured and simulated spectra were obtained for both (220)Rn and (222)Rn, in the energy range between 1 and 10 MeV. Measured calibration factors could be reproduced by the simulation, given the uncertainties involved in the measurement and simulation. The simulated alpha particle spectra can now be used to interpret spectra measured in mixed radon/thoron atmospheres. The results agreed well with measurements performed in both radon and thoron gas environments. It is concluded that the developed simulation allows for an accurate prediction of calibration factors and alpha particle energy spectra.

  7. Calibration of semiconductor detectors in the 200-8500 keV range at VNIIM.

    Science.gov (United States)

    Tereshchenko, Evgeny E; Moiseev, Nikolay

    2012-09-01

    At the ionising radiation department of the D.I. Mendeleyev Institute for Metrology, a semiconductor detector was calibrated in the energy range 200-8500 keV using (n,2γ) and (n,γ) reactions. Separate cylindrical targets (77 mm diameter and 10mm height) were made from mercuric sulphate, sodium chloride and metallic titanium. A (252)Cf spontaneous fission neutron source, placed in 150 mm diameter polyethylene ball, was used to generate thermal neutrons. The optimal target dimensions were determined taking into account the thermal neutron cross-sections and gamma-radiation attenuations in the target materials. The influence of the background radiation induced by neutrons from the walls, floors and ceilings was also taken into account. The shapes of the efficiency curves for point and volume sources in the 200-8500 keV range have been investigated. The experimental results are in good agreement with Monte-Carlo calculations. The emission rate of the 6.13 MeV photons from a (238)Pu-(13)C source was determined with an expanded uncertainty, U(c), of 10% (k=2).

  8. Multidirectional channeling analysis of epitaxial CdTe layers using an automatic RBS/channeling system

    Energy Technology Data Exchange (ETDEWEB)

    Wielunski, L.S.; Kenny, M.J. [CSIRO, Lindfield, NSW (Australia). Applied Physics Div.

    1993-12-31

    Rutherford Backscattering Spectrometry (RBS) is an ion beam analysis technique used in many fields. The high depth and mass resolution of RBS make this technique very useful in semiconductor material analysis [1]. The use of ion channeling in combination with RBS creates a powerful technique which can provide information about crystal quality and structure in addition to mass and depth resolution [2]. The presence of crystal defects such as interstitial atoms, dislocations or dislocation loops can be detected and profiled [3,4]. Semiconductor materials such as CdTe, HgTe and Hg+xCd{sub 1-x}Te generate considerable interest due to applications as infrared detectors in many technological areas. The present paper demonstrates how automatic RBS and multidirectional channeling analysis can be used to evaluate crystal quality and near surface defects. 6 refs., 1 fig.

  9. Depth of interaction and bias voltage depenence of the spectral response in a pixellated CdTe detector operating in time-over-threshold mode subjected to monochromatic X-rays

    Science.gov (United States)

    Fröjdh, E.; Fröjdh, C.; Gimenez, E. N.; Maneuski, D.; Marchal, J.; Norlin, B.; O'Shea, V.; Stewart, G.; Wilhelm, H.; Modh Zain, R.; Thungström, G.

    2012-03-01

    High stopping power is one of the most important figures of merit for X-ray detectors. CdTe is a promising material but suffers from: material defects, non-ideal charge transport and long range X-ray fluorescence. Those factors reduce the image quality and deteriorate spectral information. In this project we used a monochromatic pencil beam collimated through a 20μm pinhole to measure the detector spectral response in dependance on the depth of interaction. The sensor was a 1mm thick CdTe detector with a pixel pitch of 110μm, bump bonded to a Timepix readout chip operating in Time-Over-Threshold mode. The measurements were carried out at the Extreme Conditions beamline I15 of the Diamond Light Source. The beam was entering the sensor at an angle of \\texttildelow20 degrees to the surface and then passed through \\texttildelow25 pixels before leaving through the bottom of the sensor. The photon energy was tuned to 77keV giving a variation in the beam intensity of about three orders of magnitude along the beam path. Spectra in Time-over-Threshold (ToT) mode were recorded showing each individual interaction. The bias voltage was varied between -30V and -300V to investigate how the electric field affected the spectral information. For this setup it is worth noticing the large impact of fluorescence. At -300V the photo peak and escape peak are of similar height. For high bias voltages the spectra remains clear throughout the whole depth but for lower voltages as -50V, only the bottom part of the sensor carries spectral information. This is an effect of the low hole mobility and the longer range the electrons have to travel in a low field.

  10. The Si/CdTe semiconductor camera of the ASTRO-H Hard X-ray Imager (HXI)

    Science.gov (United States)

    Sato, Goro; Hagino, Kouichi; Watanabe, Shin; Genba, Kei; Harayama, Atsushi; Kanematsu, Hironori; Kataoka, Jun; Katsuragawa, Miho; Kawaharada, Madoka; Kobayashi, Shogo; Kokubun, Motohide; Kuroda, Yoshikatsu; Makishima, Kazuo; Masukawa, Kazunori; Mimura, Taketo; Miyake, Katsuma; Murakami, Hiroaki; Nakano, Toshio; Nakazawa, Kazuhiro; Noda, Hirofumi; Odaka, Hirokazu; Onishi, Mitsunobu; Saito, Shinya; Sato, Rie; Sato, Tamotsu; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shin`ichiro; Yuasa, Takayuki

    2016-09-01

    The Hard X-ray Imager (HXI) is one of the instruments onboard the ASTRO-H mission [1-4] to be launched in early 2016. The HXI is the focal plane detector of the hard X-ray reflecting telescope that covers an energy range from 5 to 80 keV. It will execute observations of astronomical objects with a sensitivity for point sources as faint as 1/100,000 of the Crab nebula at > 10 keV. The HXI camera - the imaging part of the HXI - is realized by a hybrid semiconductor detector system that consists of silicon (Si) and cadmium telluride (CdTe) semiconductor detectors. Here, we present the final design of the HXI camera and report on the development of the flight model. The camera is composed of four layers of Double-sided Silicon Strip Detectors (DSSDs) and one layer of CdTe Double-sided Strip Detector (CdTe-DSD), each with an imaging area of 32 mm×32 mm. The strip pitch of the Si and CdTe sensors is 250 μm, and the signals from all 1280 strips are processed by 40 Application Specified Integrated Circuits (ASICs) developed for the HXI. The five layers of sensors are vertically stacked with a 4 mm spacing to increase the detection efficiency. The thickness of the sensors is 0.5 mm for the Si, and 0.75 mm for the CdTe. In this configuration, soft X-ray photons will be absorbed in the Si part, while hard X-ray photons will go through the Si part and will be detected in the CdTe part. The design of the sensor trays, peripheral circuits, power connections, and readout schemes are also described. The flight models of the HXI camera have been manufactured, tested and installed in the HXI instrument and then on the satellite.

  11. Design of a hybrid gas proportional counter with CdTe guard counters for sup 1 sup 4 C dating system

    CERN Document Server

    Zhang, L; Hinamoto, N; Nakazawa, M; Yoshida, K

    2002-01-01

    Nowadays uniform, low-cost and large-size compound semiconductor detectors are available up to several square centimeters. We are trying to combine this technology with conventional gas detectors to upgrade an anticoincidence type proportional counter, Oeschger-type thin wall counter of 2.2 l, used for a sup 1 sup 4 C dating facility at the University of Tokyo. In order to increase the ratio of the signal to the background for smaller quantity of samples less than 1 g, an effective approach is to minimize the detector volume at higher gas pressure. However, the anticoincidence function suffers from such a small volume. Therefore we designed a new active wall gas counter of 0.13 l counting volume using CdTe compound semiconductor detectors as the wall of the gas proportional counter to perform anticoincidence. Simulation study showed that at noise thresholds less than 70 keV, the wall counters can reject above 99.8% of events arising from outer gamma rays. Measured noise levels of CdTe detectors were smaller t...

  12. Design and operation of a 2-D thin-film semiconductor neutron detector array for use as a beamport monitor

    Energy Technology Data Exchange (ETDEWEB)

    Unruh, Troy C.; Bellinger, Steven L. [SMART Laboratory, Kansas State University, Mechanical and Nuclear Engineering Department, Manhattan, KS 66506 (United States); Huddleston, David E. [Electronics Design Laboratory, Kansas State University, Manhattan, KS 66506 (United States); McNeil, Walter J.; Patterson, Eric [SMART Laboratory, Kansas State University, Mechanical and Nuclear Engineering Department, Manhattan, KS 66506 (United States); Sobering, Tim J. [Electronics Design Laboratory, Kansas State University, Manhattan, KS 66506 (United States); McGregor, Douglas S. [SMART Laboratory, Kansas State University, Mechanical and Nuclear Engineering Department, Manhattan, KS 66506 (United States)], E-mail: mcgregor@ksu.edu

    2009-06-01

    Silicon-based diodes coated with a thin film of neutron reactive materials have been shown to produce excellent low-efficiency neutron detectors. This work employs the same technology, but groups 25 equally sized and spaced diodes on a single 29 mm by 29 mm substrate. A 5x5 array was fabricated and coated with a thin film of {sup 6}LiF for use as a low-efficiency neutron beam monitor. The 5x5 neutron detector array is coupled to an array of amplifiers, allowing the response to be interpreted using a LabVIEW FPGA. The 5x5 array has been characterized in a diffracted neutron beam. This work is a part of on-going research to develop various designs of high- and low-efficiency semiconductor neutron detectors.

  13. MCNPX simulations of the silicon carbide semiconductor detector response to fast neutrons from D-T nuclear reaction

    Science.gov (United States)

    Sedlačková, Katarína; Šagátová, Andrea; Zat'ko, Bohumír; Nečas, Vladimír; Solar, Michael; Granja, Carlos

    2016-09-01

    Silicon Carbide (SiC) has been long recognized as a suitable semiconductor material for use in nuclear radiation detectors of high-energy charged particles, gamma rays, X-rays and neutrons. The nuclear interactions occurring in the semiconductor are complex and can be quantified using a Monte Carlo-based computer code. In this work, the MCNPX (Monte Carlo N-Particle eXtended) code was employed to support detector design and analysis. MCNPX is widely used to simulate interaction of radiation with matter and supports the transport of 34 particle types including heavy ions in broad energy ranges. The code also supports complex 3D geometries and both nuclear data tables and physics models. In our model, monoenergetic neutrons from D-T nuclear reaction were assumed as a source of fast neutrons. Their energy varied between 16 and 18.2 MeV, according to the accelerating voltage of the deuterons participating in D-T reaction. First, the simulations were used to calculate the optimum thickness of the reactive film composed of High Density PolyEthylene (HDPE), which converts neutral particles to charged particles and thusly enhancing detection efficiency. The dependency of the optimal thickness of the HDPE layer on the energy of the incident neutrons has been shown for the inspected energy range. Further, from the energy deposited by secondary charged particles and recoiled ions, the detector response was modeled and the effect of the conversion layer on detector response was demonstrated. The results from the simulations were compared with experimental data obtained for a detector covered by a 600 and 1300 μm thick conversion layer. Some limitations of the simulations using MCNPX code are also discussed.

  14. Radiation detectors: needs and prospects

    Energy Technology Data Exchange (ETDEWEB)

    Armantrout, G.A.

    1981-01-01

    Important applications for x- and ..gamma..-ray spectroscopy are found in prospecting, materials characterization, environmental monitoring, the life sciences, and nuclear physics. The specific requirements vary for each application with varying degrees of emphasis on either spectrometer resolution, detection efficiency, or both. Since no one spectrometer is ideally suited to this wide range of needs, compromises are usually required. Gas and scintillation spectrometers have reached a level of maturity, and recent interest has concentrated on semiconductor spectrometers. Germanium detectors are showing continuing refinement and are the spectrometers of choice for high resolution applications. The new high-Z semiconductors, such as CdTe and HgI/sub 2/, have shown steady improvement but are limited in both resolution and size and will likely be used only in applications which require their unique properties.

  15. III-V semiconductor solid solution single crystal growth

    Science.gov (United States)

    Gertner, E. R.

    1982-01-01

    The feasibility and desirability of space growth of bulk IR semiconductor crystals for use as substrates for epitaxial IR detector material were researched. A III-V ternary compound (GaInSb) and a II-VI binary compound were considered. Vapor epitaxy and quaternary epitaxy techniques were found to be sufficient to permit the use of ground based binary III-V crystals for all major device applications. Float zoning of CdTe was found to be a potentially successful approach to obtaining high quality substrate material, but further experiments were required.

  16. Multichannel, time-resolved picosecond laser ultrasound imaging and spectroscopy with custom complementary metal-oxide-semiconductor detector.

    Science.gov (United States)

    Smith, Richard J; Light, Roger A; Sharples, Steve D; Johnston, Nicholas S; Pitter, Mark C; Somekh, Mike G

    2010-02-01

    This paper presents a multichannel, time-resolved picosecond laser ultrasound system that uses a custom complementary metal-oxide-semiconductor linear array detector. This novel sensor allows parallel phase-sensitive detection of very low contrast modulated signals with performance in each channel comparable to that of a discrete photodiode and a lock-in amplifier. Application of the instrument is demonstrated by parallelizing spatial measurements to produce two-dimensional thickness maps on a layered sample, and spectroscopic parallelization is demonstrated by presenting the measured Brillouin oscillations from a gallium arsenide wafer. This paper demonstrates the significant advantages of our approach to pump probe systems, especially picosecond ultrasonics.

  17. SOI metal-oxide-semiconductor field-effect transistor photon detector based on single-hole counting.

    Science.gov (United States)

    Du, Wei; Inokawa, Hiroshi; Satoh, Hiroaki; Ono, Atsushi

    2011-08-01

    In this Letter, a scaled-down silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistor (MOSFET) is characterized as a photon detector, where photogenerated individual holes are trapped below the negatively biased gate and modulate stepwise the electron current flowing in the bottom channel induced by the positive substrate bias. The output waveforms exhibit clear separation of current levels corresponding to different numbers of trapped holes. Considering this capability of single-hole counting, a small dark count of less than 0.02 s(-1) at room temperature, and low operation voltage of 1 V, SOI MOSFET could be a unique photon-number-resolving detector if the small quantum efficiency were improved.

  18. Microbial toxicity of ionic species leached from the II-VI semiconductor materials, cadmium telluride (CdTe) and cadmium selenide (CdSe).

    Science.gov (United States)

    Ramos-Ruiz, Adriana; Zeng, Chao; Sierra-Alvarez, Reyes; Teixeira, Luiz H; Field, Jim A

    2016-11-01

    This work investigated the microbial toxicity of soluble species that can potentially be leached from the II-VI semiconductor materials, cadmium telluride and cadmium selenide. The soluble ions tested included: cadmium, selenite, selenate, tellurite, and tellurate. Their toxicity towards the acetoclastic and hydrogen-consuming trophic groups in a methanogenic consortium as well as towards a bioluminescent marine bacterium, Aliivibrio fischeri (Microtox(®) test), was assessed. The acetoclastic methanogenic activity was the most affected as evidenced by the low 50% inhibiting concentrations (IC50) values obtained of 8.6 mg L(-1) for both cadmium and tellurite, 10.2 mg L(-1) for tellurate, and 24.1 mg L(-1) for selenite. Both tellurium oxyanions caused a strong inhibition of acetoclastic methanogenesis at low concentrations, each additional increment in concentration provided progressively less inhibition increase. In the case of the hydrogenotrophic methanogenesis, cadmium followed by selenite caused the greatest inhibition with IC50 values of 2.9 and 18.0 mg L(-1), respectively. Tellurite caused a moderate effect as evidenced by a 36.8% inhibition of the methanogenic activity at the highest concentration tested, and a very mild effect of tellurate was observed. Microtox(®) analyses showed a noteworthy inhibition of cadmium, selenite, and tellurite with 50% loss in bioluminescence after 30 min of exposure of 5.5, 171.1, and 458.6 mg L(-1), respectively. These results suggest that the leaching of cadmium, tellurium and selenium ions from semiconductor materials can potentially cause microbial toxicity.

  19. Thermal characterization and determination of recombination parameters in CdTe films on glass substrates by using open photoacoustic cell technique

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-T, M.A. [Depto. de C. Basicas, ESCOM-IPN, Av. Miguel Othon de Mendizabal S/N, Col. Lindavista, CP 07738, Mexico DF (Mexico)]. E-mail: mgonzalezt@ipn.mx; Cruz-Orea, A. [Depto. de Fisica, CINVESTAV-IPN, Av. IPN No.2508, Col. San Pedro Zacatenco, CP. 07360, Mexico DF (Mexico); Albor-A, M.L. de [Depto. de Fisica, ESFM-IPN, Edif. 9, U.P. ' Adolfo Lopez Mateos' , CP 07738, Mexico DF (Mexico); Castillo-A, F. de L [Depto. de Fisica, ESFM-IPN, Edif. 9, U.P. ' Adolfo Lopez Mateos' , CP 07738, Mexico DF (Mexico)

    2005-06-01

    CdTe is a semiconductor with a wide variety of applications and perspectives for electronic industry (high-efficiency photoelectric cells, infrared radiation detectors, etc.). In the present work, we used photoacoustic (PA) technique to study the thermal properties and the surface recombination velocity in CdTe/glass samples. Experimental PA phase signal as a function of modulation frequency in a heat transmission configuration was fitted to the theoretical expression for PA signal, which takes into account the heat sources resulting from the absorption of light in semiconductors and the nonradiative processes involved, which depend on their thermal, optical and electronic transport properties. By this procedure, it was possible to determine the thermal diffusivity and the surface recombination velocity in these samples. The studied samples were thin polycrystalline CdTe film deposited on glass slides. CdTe layers were deposited by a hot-wall closed-spaced vapor transport method, known as gradient recrystallization and growth. The values for the deposition parameters used in this study were the following: 700 deg. C for the source temperature and 450 and 550 deg. C for the substrate temperatures with three different deposition times from 5 to 20 min (then three different film thicknesses were obtained). A clear increment in the surface velocity and surface roughness is observed as the film thickness is increased.

  20. Adsorption smoke detector made of thin-film metal-oxide semiconductor sensor

    CERN Document Server

    Adamian, A Z; Aroutiounian, V M

    2001-01-01

    Based on results of investigations of the thin-film smoke sensors made of Bi sub 2 O sub 3 , irresponsive to a change in relative humidity of the environment, an absorption smoke detector processing circuit, where investigated sensor is used as a sensitive element, is proposed. It is shown that such smoke detector is able to function reliably under conditions of high relative humidity of the environment (up to 100%) and it considerably exceeds the known smoke detectors by the sensitivity threshold.

  1. Optical characteristics of p-type GaAs-based semiconductors towards applications in photoemission infrared detectors

    Science.gov (United States)

    Lao, Y. F.; Perera, A. G. U.; Wang, H. L.; Zhao, J. H.; Jin, Y. J.; Zhang, D. H.

    2016-03-01

    Free-carrier effects in a p-type semiconductor including the intra-valence-band and inter-valence-band optical transitions are primarily responsible for its optical characteristics in infrared. Attention has been paid to the inter-valence-band transitions for the development of internal photoemission (IPE) mid-wave infrared (MWIR) photodetectors. The hole transition from the heavy-hole (HH) band to the spin-orbit split-off (SO) band has demonstrated potential applications for 3-5 μm detection without the need of cooling. However, the forbidden SO-HH transition at the Γ point (corresponding to a transition energy Δ0, which is the split-off gap between the HH and SO bands) creates a sharp drop around 3.6 μm in the spectral response of p-type GaAs/AlGaAs detectors. Here, we report a study on the optical characteristics of p-type GaAs-based semiconductors, including compressively strained InGaAs and GaAsSb, and a dilute magnetic semiconductor, GaMnAs. A model-independent fitting algorithm was used to derive the dielectric function from experimental reflection and transmission spectra. Results show that distinct absorption dip at Δ0 is observable in p-type InGaAs and GaAsSb, while GaMnAs displays enhanced absorption without degradation around Δ0. This implies the promise of using GaMnAs to develop MWIR IPE detectors. Discussions on the optical characteristics correlating with the valence-band structure and free-hole effects are presented.

  2. X-ray diffuse scattering for evaluation of wide bandgap semiconductor nuclear radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Goorsky, M.S. [University of Southern California, Los Angeles, CA (United States). Dept. of Mater. Sci. and Eng.; Yoon, H. [University of Southern California, Los Angeles, CA (United States). Dept. of Mater. Sci. and Eng.; Schieber, M. [Hebrew Univ., Jerusalem (Israel). Graduate Sch. of Appl. Sci.; James, R.B. [Sandia Nat. Labs., Livermore, CA (United States). Dept. 8347; McGregor, D.S. [Sandia Nat. Labs., Livermore, CA (United States). Dept. 8347; Natarajan, M. [TN Technol., Round Rock, TX (United States)

    1996-10-01

    The crystalline perfection of solid state radiation detectors was examined using triple axis x-ray diffraction. Triple axis techniques provide a means to analyze the origin of diffraction peak broadening: the effects of strain (due to deviations in alloy composition or stoichiometry) and lattice tilts (mosaic structure) can be separated. Cd{sub 1-x}Zn{sub x}Te (x{approx}0.1), HgI{sub 2}, and GaAs detector materials were studied. In the cases of Cd{sub 1-x}Zn{sub x}Te and HgI{sub 2} the crystalline properties of detectors with different spectral responses to {gamma}-radiation were determined. Increased mosaicity was universally found to be related to deteriorated detector properties. For Cd{sub 1-x}Zn{sub x}Te, detectors with poor performance possessed greater levels of diffuse scatter due to lattice tilts than did high quality detectors. For GaAs, low angle grain boundaries were attributed to impaired detector performance. Additionally, in large HgI{sub 2} detectors, deviations from stoichiometry were also related to reduced performance. Interestingly, HgI{sub 2} detectors which possessed a sharp spectral response to {gamma}-radiation but also showed polarization were of comparable crystallinity to those detectors which did not exhibit polarization effects. This initial analysis suggests that polarization is related to native point defects or chemical impurities which do not significantly alter the crystallinity of the material. Overall, within a given class of materials, improved detector performance (better spectral response) always correlated with better material quality. (orig.).

  3. Operational Experience of the ATLAS SemiConductor Tracker and Pixel Detector

    CERN Document Server

    Robinson, Dave; The ATLAS collaboration

    2016-01-01

    The tracking performance of the ATLAS detector relies critically on the silicon and gaseous tracking subsystems that form the ATLAS Inner Detector. Those subsystems have undergone significant hardware and software upgrades to meet the challenges imposed by the higher collision energy, pileup and luminosity that are being delivered by the LHC during Run2. The key status and performance metrics of the Pixel Detector and the Semi Conductor Tracker are summarised, and the operational experience and requirements to ensure optimum data quality and data taking efficiency are described.

  4. Soft x-ray intensity profile measurements of electron cyclotron heated plasmas using semiconductor detector arrays in GAMMA 10 tandem mirror.

    Science.gov (United States)

    Minami, R; Imai, T; Kariya, T; Numakura, T; Eguchi, T; Kawarasaki, R; Nakazawa, K; Kato, T; Sato, F; Nanzai, H; Uehara, M; Endo, Y; Ichimura, M

    2014-11-01

    Temporally and spatially resolved soft x-ray analyses of electron cyclotron heated plasmas are carried out by using semiconductor detector arrays in the GAMMA 10 tandem mirror. The detector array has 16-channel for the measurements of plasma x-ray profiles so as to make x-ray tomographic reconstructions. The characteristics of the detector array make it possible to obtain spatially resolved plasma electron temperatures down to a few tens eV and investigate various magnetohydrodynamic activities. High power electron cyclotron heating experiment for the central-cell region in GAMMA 10 has been started in order to reduce the electron drag by increasing the electron temperature.

  5. Using triple gamma coincidences with a pixelated semiconductor Compton-PET scanner: a simulation study

    Science.gov (United States)

    Kolstein, M.; Chmeissani, M.

    2016-01-01

    The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 × 1 × 2 mm3 guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using β+-γ emitting isotopes with a Compton-PET scanner. When the β+ annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.

  6. Next Generation Semiconductor-Based Radiation Detectors Using Cadmium Magnesium Telluride

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, Sudhir B [Brimrose Technology Corporation, Sparks Glencoe, MD (United States); Kutcher, Susan W [Brimrose Technology Corporation, Sparks Glencoe, MD (United States); Palsoz, Witold [Brimrose Technology Corporation, Sparks Glencoe, MD (United States); Berding, Martha [SRI International, Menlo Park, CA (United States); Burger, Arnold [Brimrose Technology Corporation, Sparks Glencoe, MD (United States)

    2014-11-17

    The primary objective of Phase I was to perform extensive studies on the purification, crystal growth and annealing procedures of CdMgTe to gain a clear understanding of the basic material properties to enable production of detector material with performance comparable to that of CdZnTe. Brimrose utilized prior experience in the growth and processing of II-VI crystals and produced high purity material and good quality single crystals of CdMgTe. Processing techniques for these crystals including annealing, mechanical and chemical polishing, surface passivation and electrode fabrication were developed. Techniques to characterize pertinent electronic characteristics were developed and gamma ray detectors were fabricated. Feasibility of the development of comprehensive defect modeling in this new class of material was demonstrated by our partner research institute SRI International, to compliment the experimental work. We successfully produced a CdMgTe detector that showed 662 keV gamma response with energy resolution of 3.4% (FWHM) at room temperature, without any additional signal correction. These results are comparable to existing CdZnTe (CZT) technology using the same detector size and testing conditions. We have successfully demonstrated detection of gamma-radiation from various isotopes/sources, using CdMgTe thus clearly proving the feasibility that CdMgTe is an excellent, low-cost alternative to CdZnTe.

  7. SEMICONDUCTOR DEVICES Fabrication and characterization of an AlGaN/PZT detector

    Science.gov (United States)

    Yan, Zhang; Jinglan, Sun; Nili, Wang; Li, Han; Xiangyang, Liu; Xiangyang, Li; Xiangjian, Meng

    2010-12-01

    Design, fabrication and characterization of a novel two-color detector for ultraviolet and infrared applications are reported. The detector has a simple multilayer structure composed of n-Al0.3Ga0.7N/i-GaN/p-GaN/SiO2/LaNiO3/PZT/Pt fabricated on a sapphire substrate. Ultraviolet and infrared properties are measured. For the ultraviolet region, a flat band spectral response is achieved in the 302-363 nm band. The detector displays an unbiased responsivity of 0.064 A/W at 355 nm. The current-voltage curve shows that current at zero bias is -1.57 × 10-12 A. This led to a detectivity of 1.81 × 1011 cm · Hz1/2/W. In the infrared region, the detectivity of the detector is 1.58 × 105 cm · Hz1/2/W at 4 μm.

  8. Performance optimization of a free space optical interconnect system with a metal-semiconductor-metal detector

    Science.gov (United States)

    Al-Ababneh, Nedal; Khader, Ateka

    2011-08-01

    In this paper we study the possibility and the potentiality of using metal semiconductor-metal photodetector (MSM-PD) in three-dimensional parallel free space optical interconnect (FSOI) systems. The signal-to-noise ratio (SNR) and time response are used as performance measures to optimize the geometry of MSM-PD used in FSOI systems. Both SNR and time response are evaluated, analyzed, and their dependence on feature parameters of the MSM-PD, including finger size, spacing, and number of fingers, are considered. Based on the results obtained, we show that the use of MSM-PD in FSOI improves the interconnect speed at a given acceptable SNR.

  9. Micro and nanophotonics for semiconductor infrared detectors towards an ultimate uncooled device

    CERN Document Server

    Jakšic, Zoran

    2014-01-01

    The advent of microelectromechanic system (MEMS) technologies and nanotechnologies has resulted in a multitude of structures and devices with ultra compact dimensions and with vastly enhanced or even completely novel properties. In the field of photonics it resulted in the appearance of new paradigms, including photonic crystals that exhibit photonic bandgap and represent an optical analog of semiconductors and metamaterials that have subwavelength features and may have almost arbitrary values of effective refractive index, including those below zero. In addition to that, a whole new field of

  10. SU-C-201-03: Coded Aperture Gamma-Ray Imaging Using Pixelated Semiconductor Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, S [Wayne State University, Detroit, MI (United States); Kaye, W; Jaworski, J [H3D, Inc., Ann Arbor, MI (United States); He, Z [University of Michigan, Ann Arbor, MI (United States)

    2015-06-15

    Purpose: Improved localization of gamma-ray emissions from radiotracers is essential to the progress of nuclear medicine. Polaris is a portable, room-temperature operated gamma-ray imaging spectrometer composed of two 3×3 arrays of thick CdZnTe (CZT) detectors, which detect gammas between 30keV and 3MeV with energy resolution of <1% FWHM at 662keV. Compton imaging is used to map out source distributions in 4-pi space; however, is only effective above 300keV where Compton scatter is dominant. This work extends imaging to photoelectric energies (<300keV) using coded aperture imaging (CAI), which is essential for localization of Tc-99m (140keV). Methods: CAI, similar to the pinhole camera, relies on an attenuating mask, with open/closed elements, placed between the source and position-sensitive detectors. Partial attenuation of the source results in a “shadow” or count distribution that closely matches a portion of the mask pattern. Ideally, each source direction corresponds to a unique count distribution. Using backprojection reconstruction, the source direction is determined within the field of view. The knowledge of 3D position of interaction results in improved image quality. Results: Using a single array of detectors, a coded aperture mask, and multiple Co-57 (122keV) point sources, image reconstruction is performed in real-time, on an event-by-event basis, resulting in images with an angular resolution of ∼6 degrees. Although material nonuniformities contribute to image degradation, the superposition of images from individual detectors results in improved SNR. CAI was integrated with Compton imaging for a seamless transition between energy regimes. Conclusion: For the first time, CAI has been applied to thick, 3D position sensitive CZT detectors. Real-time, combined CAI and Compton imaging is performed using two 3×3 detector arrays, resulting in a source distribution in space. This system has been commercialized by H3D, Inc. and is being acquired for

  11. Fluorocarbon evaporative cooling developments for the ATLAS pixel and semiconductor tracking detectors

    CERN Document Server

    Anderssen, E; Berry, S; Bonneau, P; Bosteels, Michel; Bouvier, P; Cragg, D; English, R; Godlewski, J; Górski, B; Grohmann, S; Hallewell, G D; Hayler, T; Ilie, S; Jones, T; Kadlec, J; Lindsay, S; Miller, W; Niinikoski, T O; Olcese, M; Olszowska, J; Payne, B; Pilling, A; Perrin, E; Sandaker, H; Seytre, J F; Thadome, J; Vacek, V

    1999-01-01

    Heat transfer coefficients 2-5.103 Wm-2K-1 have been measured in a 3.6 mm I.D. heated tube dissipating 100 Watts - close to the full equivalent power (~110 W) of a barrel SCT detector "stave" - over a range of power dissipations and mass flows in the above fluids. Aspects of full-scale evaporative cooling circulator design for the ATLAS experiment are discussed, together with plans for future development.

  12. MCNPX Monte Carlo simulations of particle transport in SiC semiconductor detectors of fast neutrons

    Science.gov (United States)

    Sedlačková, K.; Zat'ko, B.; Šagátová, A.; Pavlovič, M.; Nečas, V.; Stacho, M.

    2014-05-01

    The aim of this paper was to investigate particle transport properties of a fast neutron detector based on silicon carbide. MCNPX (Monte Carlo N-Particle eXtended) code was used in our study because it allows seamless particle transport, thus not only interacting neutrons can be inspected but also secondary particles can be banked for subsequent transport. Modelling of the fast-neutron response of a SiC detector was carried out for fast neutrons produced by 239Pu-Be source with the mean energy of about 4.3 MeV. Using the MCNPX code, the following quantities have been calculated: secondary particle flux densities, reaction rates of elastic/inelastic scattering and other nuclear reactions, distribution of residual ions, deposited energy and energy distribution of pulses. The values of reaction rates calculated for different types of reactions and resulting energy deposition values showed that the incident neutrons transfer part of the carried energy predominantly via elastic scattering on silicon and carbon atoms. Other fast-neutron induced reactions include inelastic scattering and nuclear reactions followed by production of α-particles and protons. Silicon and carbon recoil atoms, α-particles and protons are charged particles which contribute to the detector response. It was demonstrated that although the bare SiC material can register fast neutrons directly, its detection efficiency can be enlarged if it is covered by an appropriate conversion layer. Comparison of the simulation results with experimental data was successfully accomplished.

  13. Optimizing the design and analysis of cryogenic semiconductor dark matter detectors for maximum sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Pyle, Matt Christopher [Stanford Univ., CA (United States)

    2012-01-01

    In this thesis, we illustrate how the complex E- field geometry produced by interdigitated electrodes at alternating voltage biases naturally encodes 3D fiducial volume information into the charge and phonon signals and thus is a natural geometry for our next generation dark matter detectors. Secondly, we will study in depth the physics of import to our devices including transition edge sensor dynamics, quasi- particle dynamics in our Al collection fins, and phonon physics in the crystal itself so that we can both understand the performance of our previous CDMS II device as well as optimize the design of our future devices. Of interest to the broader physics community is the derivation of the ideal athermal phonon detector resolution and it's T3 c scaling behavior which suggests that the athermal phonon detector technology developed by CDMS could also be used to discover coherent neutrino scattering and search for non-standard neutrino interaction and sterile neutrinos. These proposed resolution optimized devices can also be used in searches for exotic MeV-GeV dark matter as well as novel background free searches for 8GeV light WIMPs.

  14. Medical Compton cameras based on semiconductor detectors design and experimental development

    CERN Document Server

    Scannavini, M G

    2001-01-01

    The work presented in this thesis is aimed at the study of Compton scatter as an alternative method of collimating gamma-rays in nuclear medicine applications. Conventional approaches to radioisotope medical imaging and their current limitations are examined. The theory of electronic collimation based on Compton scatter is introduced and it is shown that in principle its application could provide an advantageous imaging method, with both high spatial resolution and high sensitivity. The current status of research in the field, of Compton cameras is assessed and potential niches for applications of clinical interest are suggested. The criteria for the design of a Compton scatter camera are examined. A variety of semiconductors are considered for the construction of an electronic collimator and results from Monte Carlo computer simulations are presented for photon energies of clinical interest. It is concluded that the most viable approach is to design a silicon collimator for the imaging of high-energy (511 ke...

  15. Neural-based pile-up correction and ballistic deficit correction of X-ray semiconductor detectors using the Monte Carlo simulation and the Ramo theorem

    Science.gov (United States)

    Kafaee, Mahdi; Moussavi Zarandi, Ali; Taheri, Ali

    2016-03-01

    Pile-up distortion is a common problem in many nuclear radiation detection systems, especially in high count rates. It can be solved by hardware-based pile-up rejections, but there is no complete pile-up elimination in this way. Additionally, the methods can lead to poor quantitative results. Generally, time characteristics of semiconductor detector pulses are different from Scintillator detector pulses due to ballistic deficit. Hence, pulse processing-based pile-up correction in the detectors should consider this specification. In this paper, the artificial neural network pile-up correction method is applied for silicon detector piled-up pulses. For this purpose, the interaction of photons with a silicon detector is simulated by the MCNP4c code and the pulse current is calculated by Ramo's theorem. In this approach, we use a sub-Nyquist frequency sampling. The results show that the proposed method is reliable for pile-up correction and ballistic deficit in semiconductor detectors. The technique is remarkable for commercial considerations and high-speed, real-time calculations.

  16. Status of radiation damage measurements in room temperature semiconductor radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Franks, L.A.; James, R.B.

    1998-04-01

    The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI{sub 2}) is reviewed for the purpose of determining their applicability to space applications. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 10{sup 10} p/cm{sup 2} and significant bulk leakage after 10{sup 12} p/cm{sup 2}. CZT exposed to 200 MeV protons shows a two-fold loss in energy resolution after a fluence of 5 {times} 10{sup 9} p/cm{sup 2} in thick (3 mm) planar devices but little effect in 2 mm devices. No energy resolution effects were noted from moderated fission spectrum neutrons after fluences up to 10{sup 10} n/cm{sup 2}, although activation was evident. CT detectors show resolution losses after fluences of 3 {times} 10{sup 9} p/cm{sup 2} at 33 MeV for chlorine-doped detectors. Indium doped material may be more resistant. Neutron exposures (8 MeV) caused resolution losses after fluences of 2 {times} 10{sup 10} n/cm{sup 2}. Mercuric iodide has been studied with intermediate energy protons (10 to 33 MeV) at fluences up to 10{sup 12} p/cm{sup 2} and with 1.5 GeV protons at fluences up to 1.2 {times} 10{sup 8} p/cm{sup 2}. Neutron exposures at 8 MeV have been reported at fluences up to 10{sup 15} n/cm{sup 2}. No radiation damage was found under these irradiation conditions.

  17. Ultrafast nuclear myocardial perfusion imaging on a new gamma camera with semiconductor detector technique: first clinical validation

    Energy Technology Data Exchange (ETDEWEB)

    Buechel, Ronny R.; Herzog, Bernhard A.; Husmann, Lars; Burger, Irene A.; Pazhenkottil, Aju P.; Treyer, Valerie; Valenta, Ines; Schulthess, Patrick von; Nkoulou, Rene; Wyss, Christophe A. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); Kaufmann, Philipp A. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); University of Zurich, Zurich Center for Integrative Human Physiology (ZIHP), Zurich (Switzerland)

    2010-04-15

    To assess the diagnostic performance of a novel ultrafast cardiac gamma camera with cadmium-zinc-telluride (CZT) solid-state semiconductor detectors for nuclear myocardial perfusion imaging (MPI). The study group comprised 75 consecutive patients (55 men, BMI range 19-45 kg/m{sup 2}) who underwent a 1-day {sup 99m}Tc-tetrofosmin adenosine-stress/rest imaging protocol. Scanning was performed first on a conventional dual-detector SPECT gamma camera (Ventri, GE Healthcare) with a 15-min acquisition time each for stress and rest. All scans were immediately repeated on an ultrafast CZT camera (Discovery 530 NMc, GE Healthcare) with a 3-min scan time for stress and a 2-min scan time for rest. Clinical agreement (normal, ischaemia, scar) between CZT and SPECT was assessed for each patient and for each coronary territory using SPECT MPI as the reference standard. Segmental myocardial tracer uptake values (percent of maximum) using a 20-segment model and left ventricular ejection fraction (EF) values obtained using CZT were compared with those obtained using conventional SPECT by intraclass correlation and by calculating Bland-Altman limits of agreement. There was excellent clinical agreement between CZT and conventional SPECT on a per-patient basis (96.0%) and on a per-vessel territory basis (96.4%) as shown by a highly significant correlation between segmental tracer uptake values (r=0.901, p<0.001). Similarly, EF values for both scanners were highly correlated (r=0.976, p<0.001) with narrow Bland-Altman limits of agreement (-5.5-10.6%). The novel CZT camera allows a more than fivefold reduction in scan time and provides clinical information equivalent to conventional standard SPECT MPI. (orig.)

  18. Quantum efficiency of a single microwave photon detector based on a semiconductor double quantum dot

    Science.gov (United States)

    Wong, Clement H.; Vavilov, Maxim G.

    2017-01-01

    Motivated by recent interest in implementing circuit quantum electrodynamics with semiconducting quantum dots, we consider a double quantum dot (DQD) capacitively coupled to a superconducting resonator that is driven by the microwave field of a superconducting transmission line. We analyze the DQD current response using input-output theory and show that the resonator-coupled DQD is a sensitive microwave single photon detector. Using currently available experimental parameters of DQD-resonator coupling and dissipation, including the effects of 1 /f charge noise and phonon noise, we determine the parameter regime for which incident photons are completely absorbed and near-unit ≳98 % efficiency can be achieved. We show that this regime can be reached by using very high quality resonators with quality factor Q ≃105 .

  19. First Investigation on a novel 2D position sensitive semiconductor detector concept

    CERN Document Server

    Bassignana, D; Jaramillo, R; Lozano, M; Munoz, F.J; Pellegrini, G; Quirion, D; Vila, I

    2012-01-01

    This paper presents a first study of the performance of a novel 2D position-sensitive microstrip detector, where the resistive charge division method was implemented by replacing the metallic electrodes with resistive electrodes made of polycrystalline silicon. A characterization of two proof-of-concept prototypes with different values of the electrode resistivity was carried out using a pulsed Near Infra-Red laser. The experimental data were compared with the electrical simulation of the sensor equivalent circuit coupled to simple electronics readout circuits. The good agreement between experimental and simulation results establishes the soundness of resistive charge division method in silicon microstrip sensors and validates the developed simulation as a tool for the optimization of future sensor prototypes. Spatial resolution in the strip length direction depends on the ionizing event position. The average value obtained from the protype analysis is close to 1.2% of the strip length for a 6 MIP signal.

  20. Measurements on semiconductor and scintillator detectors at the Advanced Light Source (Conference Presentation)

    Science.gov (United States)

    Camarda, Giuseppe S.; Bolotnikov, Aleksey E.; Cui, Yonggang; Gul, Rubi; Hossain, Anwar; Roy, Utpal N.; Yang, Ge; James, Ralph B.; Vanier, Peter E.

    2016-09-01

    During the transition period between closure of Beamline X27B at BNL's NSLS and the opening of Beamline MID at NSLS-II, we began operation of LBNL's ALS Beamline 3.3.2 to carry out our radiation detection materials RD. Measurements performed at this Beamline include, X-ray Detector Response Mapping and White Beam X-ray Diffraction Topography (WBXDT), among others. We will introduce the capabilities of the Beamline and present the most recent results obtained on CdZnTe and scintillators. The goal of the studies on CdZnTe is to understand the origin and effects of subgrain boundaries and help to visualize the presence of a higher concentration of impurities, which might be responsible for the deterioration of the energy resolution and response uniformity in the vicinity of the sub-grain boundaries. The results obtained in the second year of measurements will be presented.

  1. CdTe Timepix detectors for single-photon spectroscopy and linear polarimetry of high-flux hard x-ray radiation.

    Science.gov (United States)

    Hahn, C; Weber, G; Märtin, R; Höfer, S; Kämpfer, T; Stöhlker, Th

    2016-04-01

    Single-photon spectroscopy of pulsed, high-intensity sources of hard X-rays - such as laser-generated plasmas - is often hampered by the pileup of several photons absorbed by the unsegmented, large-volume sensors routinely used for the detection of high-energy radiation. Detectors based on the Timepix chip, with a segmentation pitch of 55 μm and the possibility to be equipped with high-Z sensor chips, constitute an attractive alternative to commonly used passive solutions such as image plates. In this report, we present energy calibration and characterization measurements of such devices. The achievable energy resolution is comparable to that of scintillators for γ spectroscopy. Moreover, we also introduce a simple two-detector Compton polarimeter setup with a polarimeter quality of (98 ± 1)%. Finally, a proof-of-principle polarimetry experiment is discussed, where we studied the linear polarization of bremsstrahlung emitted by a laser-driven plasma and found an indication of the X-ray polarization direction depending on the polarization state of the incident laser pulse.

  2. Measurement of effect of electron cyclotron heating in a tandem mirror plasma using a semiconductor detector array and an electrostatic energy analyzer

    Science.gov (United States)

    Minami, R.; Imai, T.; Kariya, T.; Numakura, T.; Uehara, M.; Tsumura, K.; Ebashi, Y.; Kajino, S.; Endo, Y.; Nakashima, Y.

    2016-11-01

    Temporally and spatially resolved soft x-ray and end-loss-electron analyses of the electron cyclotron heated plasmas are carried out by using a semiconductor detector array and an electrostatic energy analyzer in the GAMMA 10 tandem mirror. The flux and the energy spectrum of the end loss electrons are measured by a multi-grid energy analyzer. Recently, the electron cyclotron heating power modulation experiments have been started in order to generate and control the high heat flux and to make the edge localized mode-like intermittent heat load pattern for the divertor simulation studies by the use of these detectors for electron properties.

  3. CdTe ambulatory ventricular function monitor

    Energy Technology Data Exchange (ETDEWEB)

    Lazewatsky, J.L.; Alpert, N.M.; Moore, R.H.; Boucher, C.A.; Strauss, H.W.

    1979-01-01

    A prototype device consisting of two arrays of CdTe detectors, ECG amplifiers and gate, microprocessor, and tape recorder was devised to record simultaneous ECG and radionuclide blood pool data from the left ventricle for extended periods during normal activity. The device is intended to record information concerning both normal and abnormal physiology of the heart and to permit the evaluation of new pharmaceuticals under everyday conditions. Preliminary results indicate that the device is capable of recording and reading out data from both phantoms and patients.

  4. High-contrast X-ray micro-tomography of low attenuation samples using large area hybrid semiconductor pixel detector array of 10 × 5 Timepix chips

    Science.gov (United States)

    Karch, J.; Krejci, F.; Bartl, B.; Dudak, J.; Kuba, J.; Kvacek, J.; Zemlicka, J.

    2016-01-01

    State-of-the-art hybrid pixel semiconductor detectors provide excellent imaging properties such as unlimited dynamic range, high spatial resolution, high frame rate and energy sensitivity. Nevertheless, a limitation in the use of these devices for imaging has been the small sensitive area of a few square centimetres. In the field of microtomography we make use of a large area pixel detector assembled from 50 Timepix edgeless chips providing fully sensitive area of 14.3 × 7.15 cm2. We have successfully demonstrated that the enlargement of the sensitive area enables high-quality tomographic measurements of whole objects with high geometrical magnification without any significant degradation in resulting reconstructions related to the chip tilling and edgeless sensor technology properties. The technique of micro-tomography with the newly developed large area detector is applied for samples formed by low attenuation, low contrast materials such a seed from Phacelia tanacetifolia, a charcoalified wood sample and a beeswax seal sample.

  5. Improved performance of GaN metal-semiconductor-metal ultraviolet detectors by depositing SiO2 nanoparticles on a GaN surface

    Science.gov (United States)

    Sun, Xiaojuan; Li, Dabing; Jiang, Hong; Li, Zhiming; Song, Hang; Chen, Yiren; Miao, Guoqing

    2011-03-01

    GaN metal-semiconductor-metal (MSM) ultraviolet detectors were investigated by depositing different density of SiO2 nanoparticles (SNPs) on the GaN. It was shown that the dark current of the detectors with SNPs was more than one order of magnitude lower than that without SNPs and the peak responsivity was enhanced after deposition of the SNPs. Atomic force microscopy observations indicated that the SNPs usually formed at the termination of screw and mixed dislocations, and further current-voltage measurements showed that the leakage of the Schottky contact for the GaN MSM detector decreased with deposited the SNPs. Moreover, the leakage obeyed the Frenkel-Poole emission model, which meant that the mechanism for improving the performance is the SNPs passivation of the dislocations followed by the reduction in the dark current.

  6. SU-E-T-231: Measurements of Gold Nanoparticle-Mediated Proton Dose Enhancement Due to Particle-Induced X-Ray Emission and Activation Products Using Radiochromic Films and CdTe Detector

    Energy Technology Data Exchange (ETDEWEB)

    Cho, J; Cho, S [Dept. of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX (United States); Manohar, N [Dept. of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX (United States); Medical Physics Program, Georgia Institute of Technology, Atlanta, GA (Georgia); Krishnan, S [Dept. of Radiation Oncology, UT MD Anderson Cancer Center, Houston, TX (United States)

    2014-06-01

    Purpose: There have been several reports of enhanced cell-killing and tumor regression when tumor cells and mouse tumors were loaded with gold nanoparticles (GNPs) prior to proton irradiation. While particle-induced xray emission (PIXE), Auger electrons, secondary electrons, free radicals, and biological effects have been suggested as potential mechanisms responsible for the observed GNP-mediated dose enhancement/radiosensitization, there is a lack of quantitative analysis regarding the contribution from each mechanism. Here, we report our experimental effort to quantify some of these effects. Methods: 5-cm-long cylindrical plastic vials were filled with 1.8 mL of either water or water mixed with cylindrical GNPs at the same gold concentration (0.3 mg Au/g) as used in previous animal studies. A piece of EBT2 radiochromic film (30-µm active-layer sandwiched between 80/175-µm outer-layers) was inserted along the long axis of each vial and used to measure dose enhancement due to PIXE from GNPs. Vials were placed at center-of-modulation (COM) and 3-cm up-/down-stream from COM and irradiated with 5 different doses (2–10 Gy) using 10-cm-SOBP 160-MeV protons. After irradiation, films were cleaned and read to determine the delivered dose. A vial containing spherical GNPs (20 mg Au/g) was also irradiated, and gamma-rays from activation products were measured using a cadmium-telluride (CdTe) detector. Results: Film measurements showed no significant dose enhancement beyond the experimental uncertainty (∼2%). There was a detectable activation product from GNPs, but it appeared to contribute to dose enhancement minimally (<0.01%). Conclusion: Considering the composition of EBT2 film, it can be inferred that gold characteristic x-rays from PIXE and their secondary electrons make insignificant contribution to dose enhancement. The current investigation also suggests negligible dose enhancement due to activation products. Thus, previously-reported GNP-mediated proton dose

  7. Defect complexes formed with Ag atoms in CDTE, ZnTe, and ZnSe

    CERN Document Server

    Wolf, H; Ostheimer, V; Hamann, J; Lany, S; Wichert, T

    2000-01-01

    Using the radioactive acceptor $^{111}\\!$Ag for perturbed $\\gamma$-$\\gamma$-angular correlation (PAC) spectroscopy for the first time, defect complexes formed with Ag are investigated in the II-VI semiconductors CdTe, ZnTe and ZnSe. The donors In, Br and the Te-vacancy were found to passivate Ag acceptors in CdTe via pair formation, which was also observed in In-doped ZnTe. In undoped or Sb-doped CdTe and in undoped ZnSe, the PAC experiments indicate the compensation of Ag acceptors by the formation of double broken bond centres, which are characterised by an electric field gradient with an asymmetry parameter close to h = 1. Additionally, a very large electric field gradient was observed in CdTe, which is possibly connected with residual impurities.

  8. Thermoelectrically cooled semiconductor detectors for non-destructive analysis of works of art by means of energy dispersive X-ray fluorescence

    CERN Document Server

    Cesareo, R; Castellano, A

    1999-01-01

    Thermoelectrically cooled semiconductor detectors, such as Si-PIN, Si-drift, Cd sub 1 sub - sub x Zn sub x Te and HgI sub 2 , coupled to miniaturized low-power X-ray tubes, are well suited in portable systems for energy-dispersive X-ray fluorescence (EDXRF), analysis of archaeological samples. The Si-PIN detector is characterized by a thickness of about 300 mu m, an area of about 2x3 mm sup 2 , an energy resolution of about 200-250 eV at 5.9 keV and an entrance window of 25-75 mu m. The Si-drift detector has approximately the same area and thickness, but an energy resolution of 155 eV at 5.9 keV. The efficiency of these detectors is around 100% from 4 to 10 keV, and then decreases versus energy, reaching approx 9% at 30 keV. Coupled to a miniaturized 10 kV, 0.1 mA, Ca-anode or to a miniaturized 30 kV, 0.1 mA, W-anode X-ray tubes, portable systems can be constructed, which are able to analyse K-lines of elements up to about silver, and L-lines of heavy elements. The Cd sub 1 sub - sub x Zn sub x Te detector ha...

  9. Manufacturing of CSS CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, D. [ANTEC Solar GmbH, Rudisleben (Germany)

    2000-02-21

    Due to its basic physical and chemical properties CdTe has become a favoured base material for thin film solar cells, using robust, high-throughput manufacturing procedures. The technology shows significant potential for attaining cost levels of <0.5 Euro/W{sub p}. Close-spaced sublimation (CSS) is the fastest and simplest deposition process for both semiconductors used, CdTe and CdS, permitting in-line production at a high linear speed of about 1 m/min. The individual manufacturing steps for integrated modules are explained in view of their incorporation into the production line. ANTEC solar GmbH is engaged to enter the production of CdTe thin film modules on a scale of 10 MW{sub p} (100000 m{sup 2}) per annum, using CSS as the deposition procedure for the semiconductor films, and high-rate in-line sputtering for transparent and opaque contacts. Standard module size will be 60 x 120 cm{sup 2}. The production line is presently under construction. (orig.)

  10. A HEMT-Based Cryogenic Charge Amplifier with sub-100 eVee Ionization Resolution for Massive Semiconductor Dark Matter Detectors

    CERN Document Server

    Phipps, A; Sadoulet, B; Serfass, B; Jin, Y

    2016-01-01

    We present the design and noise performance of a fully cryogenic (T=4 K) HEMT-based charge amplifier for readout of massive semiconductor dark matter detectors operating at sub-Kelvin temperatures. The amplifier has been developed to allow direct detection experiments such as CDMS and EDELWEISS to probe WIMP masses below 10 GeV/$c^2$ while retaining electromagnetic background discrimination. The amplifier dissipates only 1 mW of power and has a measured noise performance three times better than traditional JFET-based charge amplifiers. The predicted optimal filter baseline ionization energy resolution using the measured intrinsic amplifier noise performance and typical detector characteristics is $\\sigma_E \\approx 100 \\,\\text{eV}_{ee}$ (33 electrons). We have measured a calibrated baseline energy resolution of $\\sigma_E = 91\\,\\text{eV}_{ee}$ when coupled to a live CDMS II detector. To our knowledge, this is the best resolution achieved on such massive ($\\approx$150 pF capacitance) radiation detectors.

  11. Infrared detectors

    CERN Document Server

    Rogalski, Antonio

    2010-01-01

    This second edition is fully revised and reorganized, with new chapters concerning third generation and quantum dot detectors, THz detectors, cantilever and antenna coupled detectors, and information on radiometry and IR optics materials. Part IV concerning focal plane arrays is significantly expanded. This book, resembling an encyclopedia of IR detectors, is well illustrated and contains many original references … a really comprehensive book.-F. Sizov, Institute of Semiconductor Physics, National Academy of Sciences, Kiev, Ukraine

  12. Phosphorus Diffusion Mechanisms and Deep Incorporation in Polycrystalline and Single-Crystalline CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Colegrove, Eric; Harvey, Steven P.; Yang, Ji-Hui; Burst, James M.; Albin, David S.; Wei, Su-Huai; Metzger, Wyatt K.

    2016-05-01

    A key challenge in cadmium telluride (CdTe) semiconductors is obtaining stable and high hole density. Group I elements substituting Cd can form ideal acceptors but easily self-compensate and diffuse quickly. For example, CdTe photovoltaics have relied on copper as a dopant, but copper creates stability problems and hole density that has not exceeded 1015 cm-3. If hole density can be increased beyond 10^16 cm-3, CdTe solar technology can exceed multicrystalline silicon and provide levelized costs of electricity below conventional energy sources. Group V elements substituting Te offer a solution, but are very difficult to incorporate. Using time-of-flight secondary-ion mass spectrometry, we examine bulk and grain boundary (GB) diffusion of phosphorous (P) in CdTe in Cd-rich conditions. We find that in addition to slow bulk diffusion and fast GB diffusion, there is a fast bulk diffusion component that enables deep P incorporation in CdTe. Detailed first-principles calculations indicate the slow bulk diffusion component is caused by substitutional P diffusion through the Te sublattice, whereas the fast bulk diffusion component is caused by P diffusing through interstitial lattice sites following the combination of a kick-out step and two rotation steps. The latter is limited in magnitude by high formation energy, but is sufficient to manipulate P incorporation. In addition to an increased physical understanding, this result opens up new experimental possibilities for Group V doping in CdTe materials.

  13. Purification and preparation of bismuth(III) iodide for application as radiation semiconductor detector; Purificacao e preparacao do cristal semicondutor de iodeto de bismuto para aplicacao como detector de radiacao

    Energy Technology Data Exchange (ETDEWEB)

    Ferraz, Caue de Mello

    2016-11-01

    This study describes the experimental procedure of a BiI{sub 3} purification method powder, aiming a future application of these semiconductor crystals as room temperature radiation detector. The Repeated Vertical Bridgman Technique was applied for the purification, based on the melting and nucleation phenomena. An ampoule filled with a maximum of 25% by volume of BiI{sub 3} powder was mounted into the Bridgman furnace and vertically moved at a speed of 2 millimeters per hour, inside the furnace with programmed thermal gradient and temperature profile, at a temperature maximum of 530 deg C. The reduction of the impurities in the BiI{sub 3}, each purification, was analysed by Instrumental Neutron Activation Analysis (INAA), in order to evaluate the efficiency of the purification technique established in this work, for trace metal impurities. It was demonstrated that the Repeated Bridgman is effective to reduce the concentration of many impurities in BiI{sub 3}, such as Ag, As, Br, Cr, K, Mo, Na and Sb. The crystalline structure of the BiI{sub 3} crystal purified twice and third times was similar to the BiI{sub 3} pattern. However, for BiI{sub 3} powder and purified once an intensity contribution of the BiOI was observed in the diffractograms. It is known that semiconductor detectors fabricated from high purity crystal exhibit significant improvement in their performance compared to those produced from low purity crystals. (author)

  14. Semiconductor sensors

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, Frank, E-mail: frank.hartmann@cern.c [Institut fuer Experimentelle Kernphysik, KIT, Wolfgang-Gaede-Str. 1, Karlsruhe 76131 (Germany)

    2011-02-01

    Semiconductor sensors have been around since the 1950s and today, every high energy physics experiment has one in its repertoire. In Lepton as well as Hadron colliders, silicon vertex and tracking detectors led to the most amazing physics and will continue doing so in the future. This contribution tries to depict the history of these devices exemplarily without being able to honor all important developments and installations. The current understanding of radiation damage mechanisms and recent R and D topics demonstrating the future challenges and possible technical solutions for the SLHC detectors are presented. Consequently semiconductor sensor candidates for an LHC upgrade and a future linear collider are also briefly introduced. The work presented here is a collage of the work of many individual silicon experts spread over several collaborations across the world.

  15. Development of surgical gamma probes with TlBr semiconductors and CsI(Tl) scintillators crystals; Desenvolvimento de sondas cirurgicas radioguiadas com semicondutores de TlBr e com cristais cintiladores de CsI (Tl)

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Fabio Eduardo da

    2006-07-01

    Radio guided surgery, using probes with radiation detectors, has been prominence in the medical area in the last decade. This technique consists in injecting a radioactive substance to concentrate in tumour and assist the localization during the surgical procedure. The radio guided surgeries allowing the identification of lymph node has revolutioned the behavior of tumour in initial stadium when are being spread by lymphatic way. The conditions imposed to the surgery due the proximity between some lymph nodes, demands of the probes, a small diameters and capacity of individual identification of these lymph nodes radiolabelled by a specific tracer. The international market supplies these probes with CdTe semiconductors and scintillators, but there is some time lack a promptly technical assistance in the Brazilian market. This work developed probes with national technology, using CsI(Tl) scintillators crystals and, in substitution to CdTe crystals semiconductors, the TlBr crystal, that is a new semiconductor detector in a world-wide development, with advantages in relation to the CdTe. Both crystals have been grown in IPEN. All the necessary electronics, specially, the preamplifier, that was also a restrictive factor for development of these types of probe in the country, have been developed with components found in the national market. Systematic measures of spatial resolution, spatial selectivity, maximum sensitivity and quality of the shielding have been carried the probes development. The results have shown that the probes, one with the CsI(Tl) crystal and another with TlBr semiconductor presented the requested performance in the international literature for radio guided probes. (author)

  16. Experimental MRI-SPECT insert system with Hybrid Semiconductor detectors Timepix for MR animal scanner Bruker 47/20

    Science.gov (United States)

    Zajicek, J.; Burian, M.; Soukup, P.; Novak, V.; Macko, M.; Jakubek, J.

    2017-01-01

    Multimodal medical imaging based on Magnetic Resonance is mainly combinated with one of the scintigraphic method like PET or SPECT. These methods provide functional information whereas magnetic resonance imaging provides high spatial resolution of anatomical information or complementary functional information. Fusion of imaging modalities allows researchers to obtain complimentary information in a single measurement. The combination of MRI with SPECT is still relatively new and challenging in many ways. The main complication of using SPECT in MRI systems is the presence of a high magnetic field therefore (ferro)magnetic materials have to be eliminated. Furthermore the application of radiofrequency fields within the MR gantry does not allow for the use of conductive structures such as the common heavy metal collimators. This work presents design and construction of an experimental MRI-SPECT insert system and its initial tests. This unique insert system consists of an MR-compatible SPECT setup with CdTe pixelated sensors Timepix tungsten collimators and a radiofrequency coil. Measurements were performed on a gelatine and tissue phantom with an embedded radioisotopic source (57Co 122 keV γ ray) inside the RF coil by the Bruker BioSpec 47/20 (4.7 T) MR animal scanner. The project was performed in the framework of the Medipix Collaboration.

  17. Blanket and Patterned Growth of CdTe on (211)Si Substrates by Metal-Organic Vapor Phase Epitaxy

    Science.gov (United States)

    2012-05-15

    REPORT Blanket and Patterned Growth Of CdTE On (211)Si Substrates By Metal-Organic Vapor Phase Epitaxy 14. ABSTRACT 16. SECURITY CLASSIFICATION OF...Metalorganic vapor phase epitaxy (MOVPE) of (211)B CdTe on (211)Si using intermediate Ge and ZnTe layers has been achieved for use as substrates for the...growth of HgCdTe infrared detector materials. The best (211)B CdTe films grown in this study display a low X-ray diffraction (XRD) rocking-curve

  18. High-Efficiency, Commercial Ready CdTe Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Sites, James R. [Colorado State Univ., Fort Collins, CO (United States)

    2015-11-19

    Colorado State’s F-PACE project explored several ways to increase the efficiency of CdTe solar cells and to better understand the device physics of those cells under study. Increases in voltage, current, and fill factor resulted in efficiencies above 17%. The three project tasks and additional studies are described in detail in the final report. Most cells studied were fabricated at Colorado State using an industry-compatible single-vacuum closed-space-sublimation (CSS) chamber for deposition of the key semiconductor layers. Additionally, some cells were supplied by First Solar for comparison purposes, and a small number of modules were supplied by Abound Solar.

  19. 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.

  20. Growth of CdTe on Si(100) surface by ionized cluster beam technique: Experimental and molecular dynamics simulation

    Science.gov (United States)

    Araghi, Houshang; Zabihi, Zabiholah; Nayebi, Payman; Ehsani, Mohammad Mahdi

    2016-10-01

    II-VI semiconductor CdTe was grown on the Si(100) substrate surface by the ionized cluster beam (ICB) technique. In the ICB method, when vapors of solid materials such as CdTe were ejected through a nozzle of a heated crucible into a vacuum region, nanoclusters were created by an adiabatic expansion phenomenon. The clusters thus obtained were partially ionized by electron bombardment and then accelerated onto the silicon substrate at 473 K by high potentials. The cluster size was determined using a retarding field energy analyzer. The results of X-ray diffraction measurements indicate the cubic zinc blende (ZB) crystalline structure of the CdTe thin film on the silicon substrate. The CdTe thin film prepared by the ICB method had high crystalline quality. The microscopic processes involved in the ICB deposition technique, such as impact and coalescence processes, have been studied in detail by molecular dynamics (MD) simulation.

  1. Possible application of scintillation detectors with semiconductor PMT for cosmic-neutron and gamma-ray detection

    Science.gov (United States)

    Mokrousov, M. I.; Vostrukhin, A. A.; Karpushkina, N. E.; Malakhov, A. V.

    2016-09-01

    Solar system planets exploration and cosmic neutrons and gamma-ray flux research have been dynamically evolving for several decades. Different scintillation crystals are used for this purpose along with photo signal receivers, such as vacuum photomultiplier tubes (PMT). Many studies are being performed in order to provide alternative devices for photon signal capture: PIN-diodes,avalanche photodiodes, semiconductor silicon photomultipliers. We study the applicability of a silicon PMT in employing highresolution crystals in space applications.

  2. 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

  3. 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.

  4. Tuning and synthesis of semiconductor nanostructures by mechanical compression

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Hongyou; Li, Binsong

    2015-11-17

    A mechanical compression method can be used to tune semiconductor nanoparticle lattice structure and synthesize new semiconductor nanostructures including nanorods, nanowires, nanosheets, and other three-dimensional interconnected structures. II-VI or IV-VI compound semiconductor nanoparticle assemblies can be used as starting materials, including CdSe, CdTe, ZnSe, ZnS, PbSe, and PbS.

  5. Thickness-Controllable Silica Coating of CdTe QDs by Reverse Microemulsion Method for the Application in the Growth of Rice

    OpenAIRE

    Aiwu Wang; Yuhong Zheng; Feng Peng

    2014-01-01

    Herein, we report the synthesis and surface modification of CdTe quantum dots (QDs) and the application in the rice growth. Water-soluble thioglycolic acid (TGA) stabilized CdTe quantum dots were synthesized firstly and then the surface modification was conducted. II–VI semiconductor nanocrystals prefer to be coated with silica as inert materials to improve their chemical properties. The toxicity of QDs reduced after the modification. Silica coated QDs were used in the growth of rice seed and...

  6. Patterning thick diffused junctions on CdTe

    CERN Document Server

    Kalliopuska, Juha; Sipilä, Heikki; Andersson, Hans; Vähänen, Sami; Eränen, Simo; Tlustos, Lukas

    2009-01-01

    Dividing the detector crystal into discrete pixels enables making an imaging detector, in which the charge collected by each pixel can be read separately. Even if the detector is not meant for imaging, patterns on the crystal surface may be used as guard structures that control and limit the flow of charges in the crystal. This has been exceedingly hard for the detector crystals having thick diffused layers. The paper reports a patterning method of the thick diffused junctions on CdTe. The patterning method of In-diffused pn-junction on CdTe chip is demonstrated by using a diamond blade. The patterning is done by removing material from the pn-junction side of the chip, so that the trenches penetrate the diffused layer. As the trenches extend deeper into the bulk than the junction, the regions separated by the trench are electrically isolated. Electrical characterization results are reported for the strips separated by trenches with various depths. The strip isolation is clearly seen in both measured leakage c...

  7. APPROACHING CRYOGENIC GE PERFORMANCE WITH PELTIER COOLED CDTE

    Energy Technology Data Exchange (ETDEWEB)

    Khusainov, A. K. (A. Kh.); Iwanczyk, J. S. (Jan S.); Patt, B. E. (Bradley E.); Prirogov, A. M. (Alexandre M.); Vo, Duc T.

    2001-01-01

    A new class of hand-held, portable spectrometers based on large area (lcm2) CdTe detectors of thickness up to 3mm has been demonstrated to produce energy resolution of between 0.3 and 0.5% FWHM at 662 keV. The system uses a charge loss correction circuit for improved efficiency, and detector temperature stabilization to ensure consistent operation of the detector during field measurements over a wide range of ambient temperature. The system can operate continuously for up to 8hrs on rechargeable batteries. The signal output from the charge loss corrector is compatible with most analog and digital spectroscopy amplifiers and multi channel analyzers. Using a detector measuring 11.2 by 9.1 by 2.13 mm3, we have recently been able to obtain the first wide-range plutonium gamma-ray isotopic analysis with other than a cryogenically cooled germanium spectrometer. The CdTe spectrometer is capable of measuring small plutonium reference samples in about one hour, covering the range from low to high burnup. The isotopic analysis software used to obtain these results was FRAM, Version 4 from LANL. The new spectrometer is expected to be useful for low-grade assay, as well as for some in-situ plutonium gamma-ray isotopics in lieu of cryogenically cooled Ge.

  8. 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.

  9. Fluorescence-suppressed time-resolved Raman spectroscopy of pharmaceuticals using complementary metal-oxide semiconductor (CMOS) single-photon avalanche diode (SPAD) detector.

    Science.gov (United States)

    Rojalin, Tatu; Kurki, Lauri; Laaksonen, Timo; Viitala, Tapani; Kostamovaara, Juha; Gordon, Keith C; Galvis, Leonardo; Wachsmann-Hogiu, Sebastian; Strachan, Clare J; Yliperttula, Marjo

    2016-01-01

    In this work, we utilize a short-wavelength, 532-nm picosecond pulsed laser coupled with a time-gated complementary metal-oxide semiconductor (CMOS) single-photon avalanche diode (SPAD) detector to acquire Raman spectra of several drugs of interest. With this approach, we are able to reveal previously unseen Raman features and suppress the fluorescence background of these drugs. Compared to traditional Raman setups, the present time-resolved technique has two major improvements. First, it is possible to overcome the strong fluorescence background that usually interferes with the much weaker Raman spectra. Second, using the high photon energy excitation light source, we are able to generate a stronger Raman signal compared to traditional instruments. In addition, observations in the time domain can be performed, thus enabling new capabilities in the field of Raman and fluorescence spectroscopy. With this system, we demonstrate for the first time the possibility of recording fluorescence-suppressed Raman spectra of solid, amorphous and crystalline, and non-photoluminescent and photoluminescent drugs such as caffeine, ranitidine hydrochloride, and indomethacin (amorphous and crystalline forms). The raw data acquired by utilizing only the picosecond pulsed laser and a CMOS SPAD detector could be used for identifying the compounds directly without any data processing. Moreover, to validate the accuracy of this time-resolved technique, we present density functional theory (DFT) calculations for a widely used gastric acid inhibitor, ranitidine hydrochloride. The obtained time-resolved Raman peaks were identified based on the calculations and existing literature. Raman spectra using non-time-resolved setups with continuous-wave 785- and 532-nm excitation lasers were used as reference data. Overall, this demonstration of time-resolved Raman and fluorescence measurements with a CMOS SPAD detector shows promise in diverse areas, including fundamental chemical research, the

  10. In vivo dosimetry with semiconductor and thermoluminescent detectors applied to head and neck cancer treatment; Dosimetria in vivo com uso de detectores semicondutores e termoluminescentes aplicada ao tratamento de cancer de cabeca e pescoco

    Energy Technology Data Exchange (ETDEWEB)

    Viegas, Claudio Castelo Branco

    2003-03-15

    In vivo dosimetry in radiotherapy, i. e, the assessment of the doses received by patients during their treatments, permits a verification of the therapy quality. A routine of in vivo dosimetry is, undoubtedly, a direct benefit for the patient. Unfortunately, in Brazil and in Latin America this procedure is still a privilege for only a few patients. This routine is of common application only in developed countries. The aim of this work is to show the viability and implementation of a routine in vivo dosimetry, using diodes semiconductors and thermoluminescent dosimeters (TLD), at the radiotherapy section of the National Institute of Cancer in Brazil, in the case of head and neck cancer treatment. In order to reach that aim, the characteristics of the response of diodes ISORAD-p and LiF:Mg;Ti (TLD-100) thermoluminescent detectors in powder form were determined. The performance of those detectors for in vivo dosimetry was tested using an RANDO Alderson anthropomorfic phantom and, once their adequacy proved for the kind of measurements proposed, they were used for dose assessment in the case of tumour treatments in the head and neck regions, for Cobalt-60 irradiations. (author)

  11. K-edge EXAFS and XANES studies of Cu in CdTe thin-film solar cells

    Science.gov (United States)

    Liu, Xiangxin; Gupta, Akhlesh; Compaan, Alvin D.; Leyarovska, Nadia; Terry, Jeff

    2002-03-01

    Copper has been identified as a very important dopant element in CdTe thin-film solar cells. Cu is a deep acceptor in CdTe and is commonly used to obtain a heavily doped, low resistance back contact to polycrystalline CdTe. Cu also helps to increase the open circuit voltage of the cell. However, Cu is also a fast diffuser in CdTe, especially along grain boundaries, and can accumulate at the CdS/CdTe junction. It is suspected of leading to cell performance degradation in some cases. The present study is designed to help identify the lattice location of the Cu in CdTe. Cu K-edge, x-ray absorption (XAS) measurements were conducted on Cu in thin films of CdTe. Experiments were performed at the MR-CAT beamline at the Advanced Photon Source. The 3 mm CdTe layers were magnetron sputtered onto fused silica substrates. Some films were diffused with Cu from a 200 Å layer of evaporated Cu. XAS spectra were collected in fluorescence geometry with a 13 elements Ge detector. Quantitative fluorescence spectroscopy measurements were also performed. Details of the Cu environment and possible changes with time will be reported.

  12. Wide Band-Gap Semiconductor Radiation Detectors: Science Fiction, Horror Story, or Headlines (460th Brookhaven Lecture)

    Energy Technology Data Exchange (ETDEWEB)

    James, Ralph (BNL Nonproliferation and National Security Department)

    2010-08-18

    With radiation constantly occurring from natural sources all around us -- from food, building materials, and rays from the sun, to name a few -- detecting radiotracers for medical procedures and other radiation to keep people safe is not easy. In order to make better use of radiation to diagnose or treat certain health conditions, or to track radiological materials being transported, stored, and used, the quest is on to develop improved radiation detectors. James gives a brief introduction on radiation detection and explain how it is used in applications ranging from medical to homeland security. He then discusses how new materials and better ways to analyze them here at the National Synchrotron Light Source (NSLS) and the future NSLS-II will lead to a new class of radiation detectors that will provide unprecedented advances in medical and industrial imaging, basic science, and the nonproliferation of nuclear materials.

  13. SEMICONDUCTOR DEVICES Parallel readout of two-element CdZnTe detectors with real-time digital signal processing

    Science.gov (United States)

    Zhubin, Shi; Linjun, Wang; Kaifeng, Qin; Jiahua, Min; Jijun, Zhang; Xiaoyan, Liang; Jian, Huang; Ke, Tang; Yiben, Xia

    2010-12-01

    Readout electronics, especially digital electronics, for two-element CdZnTe (CZT) detectors in parallel are developed. The preliminary results show the detection efficiency of the two-element CZT detectors in parallel with analog electronics is as many as 1.8 and 2.1 times the single ones, and the energy resolution (FWHM) is limited by that of the single one by the means of analog electronics. However, the digital method for signal processing will be sufficiently better by contrast with an analog method especially in energy resolution. The energy resolution by the means of digital electronics can be improved by about 26.67%, compared to that only with analog electronics, while their detection efficiency is almost the same. The cause for this difference is also discussed.

  14. CdTe devices and method of manufacturing same

    Energy Technology Data Exchange (ETDEWEB)

    Gessert, Timothy A.; Noufi, Rommel; Dhere, Ramesh G.; Albin, David S.; Barnes, Teresa; Burst, James; Duenow, Joel N.; Reese, Matthew

    2015-09-29

    A method of producing polycrystalline CdTe materials and devices that incorporate the polycrystalline CdTe materials are provided. In particular, a method of producing polycrystalline p-doped CdTe thin films for use in CdTe solar cells in which the CdTe thin films possess enhanced acceptor densities and minority carrier lifetimes, resulting in enhanced efficiency of the solar cells containing the CdTe material are provided.

  15. Thermoelectrically cooled semiconductor detectors for non-destructive analysis of works of art by means of energy dispersive X-ray fluorescence

    Science.gov (United States)

    Cesareo, Roberto; Ettore Gigante, Giovanni; Castellano, Alfredo

    1999-06-01

    Thermoelectrically cooled semiconductor detectors, such as Si-PIN, Si-drift, Cd1-xZnxTe and HgI 2, coupled to miniaturized low-power X-ray tubes, are well suited in portable systems for energy-dispersive X-ray fluorescence (EDXRF), analysis of archaeological samples. The Si-PIN detector is characterized by a thickness of about 300 μm, an area of about 2×3 mm 2, an energy resolution of about 200-250 eV at 5.9 keV and an entrance window of 25-75 μm. The Si-drift detector has approximately the same area and thickness, but an energy resolution of 155 eV at 5.9 keV. The efficiency of these detectors is around 100% from 4 to 10 keV, and then decreases versus energy, reaching ˜9% at 30 keV. Coupled to a miniaturized 10 kV, 0.1 mA, Ca-anode or to a miniaturized 30 kV, 0.1 mA, W-anode X-ray tubes, portable systems can be constructed, which are able to analyse K-lines of elements up to about silver, and L-lines of heavy elements. The Cd 1- xZn xTe detector has an area of 4 mm 2 and a thickness of 3 mm. It has an energy resolution of about 300 eV at 5.9 keV, and an efficiency of 100% over the whole range of X-rays. Finally the HgI 2 detector has an efficiency of about 100% in the whole range of X-rays, and an energy resolution of about 200 eV at 5.9 keV. Coupled to a small 50-60 kV, 1 mA, W-anode X-ray tube, portable systems can be constructed, for the analysis of practically all elements. These systems were applied to analysis in the field of archaeometry and in all applications for which portable systems are needed or at least useful (for example X-ray transmission measurements, X-ray microtomography and so on). Results of in-field use of these detectors and a comparison among these room temperature detectors in relation to concrete applications are presented. More specifically, concerning EDXRF analysis, ancient gold samples were analysed in Rome, in Mexico City and in Milan, ancient bronzes in Sassari, in Bologna, in Chieti and in Naples, and sulfur (due to pollution

  16. Thermoelectrically cooled semiconductor detectors for non-destructive analysis of works of art by means of energy dispersive X-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Cesareo, Roberto; Ettore Gigante, Giovanni; Castellano, Alfredo

    1999-06-01

    Thermoelectrically cooled semiconductor detectors, such as Si-PIN, Si-drift, Cd{sub 1-x}Zn{sub x}Te and HgI{sub 2}, coupled to miniaturized low-power X-ray tubes, are well suited in portable systems for energy-dispersive X-ray fluorescence (EDXRF), analysis of archaeological samples. The Si-PIN detector is characterized by a thickness of about 300 {mu}m, an area of about 2x3 mm{sup 2}, an energy resolution of about 200-250 eV at 5.9 keV and an entrance window of 25-75 {mu}m. The Si-drift detector has approximately the same area and thickness, but an energy resolution of 155 eV at 5.9 keV. The efficiency of these detectors is around 100% from 4 to 10 keV, and then decreases versus energy, reaching {approx}9% at 30 keV. Coupled to a miniaturized 10 kV, 0.1 mA, Ca-anode or to a miniaturized 30 kV, 0.1 mA, W-anode X-ray tubes, portable systems can be constructed, which are able to analyse K-lines of elements up to about silver, and L-lines of heavy elements. The Cd{sub 1-x}Zn{sub x}Te detector has an area of 4 mm{sup 2} and a thickness of 3 mm. It has an energy resolution of about 300 eV at 5.9 keV, and an efficiency of 100% over the whole range of X-rays. Finally the HgI{sub 2} detector has an efficiency of about 100% in the whole range of X-rays, and an energy resolution of about 200 eV at 5.9 keV. Coupled to a small 50-60 kV, 1 mA, W-anode X-ray tube, portable systems can be constructed, for the analysis of practically all elements. These systems were applied to analysis in the field of archaeometry and in all applications for which portable systems are needed or at least useful (for example X-ray transmission measurements, X-ray microtomography and so on). Results of in-field use of these detectors and a comparison among these room temperature detectors in relation to concrete applications are presented. More specifically, concerning EDXRF analysis, ancient gold samples were analysed in Rome, in Mexico City and in Milan, ancient bronzes in Sassari, in Bologna, in

  17. A metal-semiconductor-metal detector based on ZnO nanowires grown on a graphene layer.

    Science.gov (United States)

    Xu, Qiang; Cheng, Qijin; Zhong, Jinxiang; Cai, Weiwei; Zhang, Zifeng; Wu, Zhengyun; Zhang, Fengyan

    2014-02-07

    High quality ZnO nanowires (NWs) were grown on a graphene layer by a hydrothermal method. The ZnO NWs revealed higher uniform surface morphology and better structural properties than ZnO NWs grown on SiO2/Si substrate. A low dark current metal-semiconductor-metal photodetector based on ZnO NWs with Au Schottky contact has also been fabricated. The photodetector displays a low dark current of 1.53 nA at 1 V bias and a large UV-to-visible rejection ratio (up to four orders), which are significantly improved compared to conventional ZnO NW photodetectors. The improvement in UV detection performance is attributed to the existence of a surface plasmon at the interface of the ZnO and the graphene.

  18. The effect of metal-semiconductor contact on the transient photovoltaic characteristic of HgCdTe PV detector.

    Science.gov (United States)

    Cui, Haoyang; Xu, Yongpeng; Yang, Junjie; Tang, Naiyun; Tang, Zhong

    2013-01-01

    The transient photovoltaic (PV) characteristic of HgCdTe PV array is studied using an ultrafast laser. The photoresponse shows an apparent negative valley first, then it evolves into a positive peak. By employing a combined theoretical model of pn junction and Schottky potential, this photo-response polarity changing curves can be interpreted well. An obvious decreasing of ratio of negative valley to positive peak can be realized by limiting the illumination area of the array electrode. This shows that the photoelectric effect of Schottky barrier at metal-semiconductor (M/S) interface is suppressed, which will verify the correctness of the model. The characteristic parameters of transient photo-response induced from p-n junction and Schottky potential are extracted by fitting the response curve utilizing this model. It shows that the negative PV response induced by the Schottky barrier decreases the positive photovoltage generated by the pn junction.

  19. A metal-semiconductor-metal detector based on ZnO nanowires grown on a graphene layer

    Science.gov (United States)

    Xu, Qiang; Cheng, Qijin; Zhong, Jinxiang; Cai, Weiwei; Zhang, Zifeng; Wu, Zhengyun; Zhang, Fengyan

    2014-02-01

    High quality ZnO nanowires (NWs) were grown on a graphene layer by a hydrothermal method. The ZnO NWs revealed higher uniform surface morphology and better structural properties than ZnO NWs grown on SiO2/Si substrate. A low dark current metal-semiconductor-metal photodetector based on ZnO NWs with Au Schottky contact has also been fabricated. The photodetector displays a low dark current of 1.53 nA at 1 V bias and a large UV-to-visible rejection ratio (up to four orders), which are significantly improved compared to conventional ZnO NW photodetectors. The improvement in UV detection performance is attributed to the existence of a surface plasmon at the interface of the ZnO and the graphene.

  20. The Effect of Metal-Semiconductor Contact on the Transient Photovoltaic Characteristic of HgCdTe PV Detector

    Directory of Open Access Journals (Sweden)

    Haoyang Cui

    2013-01-01

    Full Text Available The transient photovoltaic (PV characteristic of HgCdTe PV array is studied using an ultrafast laser. The photoresponse shows an apparent negative valley first, then it evolves into a positive peak. By employing a combined theoretical model of pn junction and Schottky potential, this photo-response polarity changing curves can be interpreted well. An obvious decreasing of ratio of negative valley to positive peak can be realized by limiting the illumination area of the array electrode. This shows that the photoelectric effect of Schottky barrier at metal-semiconductor (M/S interface is suppressed, which will verify the correctness of the model. The characteristic parameters of transient photo-response induced from p-n junction and Schottky potential are extracted by fitting the response curve utilizing this model. It shows that the negative PV response induced by the Schottky barrier decreases the positive photovoltage generated by the pn junction.

  1. High energy resolution hard X-ray and gamma-ray imagers using CdTe diode devices

    CERN Document Server

    Watanabe, Shin; Aono, Hiroyuki; Takeda, Shin'ichiro; Odaka, Hirokazu; Kokubun, Motohide; Takahashi, Tadayuki; Nakazawa, Kazuhiro; Tajima, Hiroyasu; Onishi, Mitsunobu; Kuroda, Yoshikatsu

    2008-01-01

    We developed CdTe double-sided strip detectors (DSDs or cross strip detectors) and evaluated their spectral and imaging performance for hard X-rays and gamma-rays. Though the double-sided strip configuration is suitable for imagers with a fine position resolution and a large detection area, CdTe diode DSDs with indium (In) anodes have yet to be realized due to the difficulty posed by the segmented In anodes. CdTe diode devices with aluminum (Al) anodes were recently established, followed by a CdTe device in which the Al anodes could be segmented into strips. We developed CdTe double-sided strip devices having Pt cathode strips and Al anode strips, and assembled prototype CdTe DSDs. These prototypes have a strip pitch of 400 micrometer. Signals from the strips are processed with analog ASICs (application specific integrated circuits). We have successfully performed gamma-ray imaging spectroscopy with a position resolution of 400 micrometer. Energy resolution of 1.8 keV (FWHM: full width at half maximum) was ob...

  2. Enhanced glutathione content allows the in vivo synthesis of fluorescent CdTe nanoparticles by Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Juan P Monrás

    Full Text Available The vast application of fluorescent semiconductor nanoparticles (NPs or quantum dots (QDs has prompted the development of new, cheap and safer methods that allow generating QDs with improved biocompatibility. In this context, green or biological QDs production represents a still unexplored area. This work reports the intracellular CdTe QDs biosynthesis in bacteria. Escherichia coli overexpressing the gshA gene, involved in glutathione (GSH biosynthesis, was used to produce CdTe QDs. Cells exhibited higher reduced thiols, GSH and Cd/Te contents that allow generating fluorescent intracellular NP-like structures when exposed to CdCl(2 and K(2TeO(3. Fluorescence microscopy revealed that QDs-producing cells accumulate defined structures of various colors, suggesting the production of differently-sized NPs. Purified fluorescent NPs exhibited structural and spectroscopic properties characteristic of CdTe QDs, as size and absorption/emission spectra. Elemental analysis confirmed that biosynthesized QDs were formed by Cd and Te with Cd/Te ratios expected for CdTe QDs. Finally, fluorescent properties of QDs-producing cells, such as color and intensity, were improved by temperature control and the use of reducing buffers.

  3. Effects of various deposition times and RF powers on CdTe thin film growth using magnetron sputtering

    Science.gov (United States)

    Ghorannevis, Z.; Akbarnejad, E.; Ghoranneviss, M.

    2016-09-01

    Cadmium telluride (CdTe) is a p-type II-VI compound semiconductor, which is an active component for producing photovoltaic solar cells in the form of thin films, due to its desirable physical properties. In this study, CdTe film was deposited using the radio frequency (RF) magnetron sputtering system onto a glass substrate. To improve the properties of the CdTe film, effects of two experimental parameters of deposition time and RF power were investigated on the physical properties of the CdTe films. X-ray Diffraction (XRD), atomic force microscopy (AFM) and spectrophotometer were used to study the structural, morphological and optical properties of the CdTe samples grown at different experimental conditions, respectively. Our results suggest that film properties strongly depend on the experimental parameters and by optimizing these parameters, it is possible to tune the desired structural, morphological and optical properties. From XRD data, it is found that increasing the deposition time and RF power leads to increasing the crystallinity as well as the crystal sizes of the grown film, and all the films represent zinc blende cubic structure. Roughness values given from AFM images suggest increasing the roughness of the CdTe films by increasing the RF power and deposition times. Finally, optical investigations reveal increasing the film band gaps by increasing the RF power and the deposition time.

  4. Selective CdTe Nanoheteroepitaxial Growth on Si(100) Substrates Using the Close-Spaced Sublimation Technique Without the Use of a Mask

    Science.gov (United States)

    Diaz, A.; Quinones, S. A.; Ferrer, D. A.

    2013-06-01

    The development of HgCdTe detectors requires high sensitivity, small pixel size, low defect density, long-term thermal-cycling reliability, and large-area substrates. CdTe bulk substrates were initially used for epitaxial growth of HgCdTe films. However, CdTe has a lattice mismatch with long-wavelength infrared (LWIR) and middle-wavelength infrared (MWIR) HgCdTe that results in detrimental dislocation densities above mid-106 cm-2. This work explores the use of CdTe/Si as a possible substrate for HgCdTe detectors. Although there is a 19% lattice mismatch between CdTe and Si, the nanoheteroepitaxy (NHE) technique makes it possible to grow CdTe on Si substrates with fewer defects at the CdTe/Si interface. In this work, Si(100) was patterned using photolithography and dry etching to create 500-nm to 1- μm pillars. CdTe was selectively deposited on the pillar surfaces using the close-spaced sublimation (CSS) technique. Scanning electron microscopy (SEM) was used to characterize the CdTe selective growth and grain morphology, and transmission electron microscopy (TEM) was used to analyze the structure and quality of the grains. CdTe selectivity was achieved for most of the substrate and source temperatures used in this study. The ability to selectively deposit CdTe on patterned Si(100) substrates without the use of a mask or seed layer has not been observed before using the CSS technique. The results from this study confirm that CSS has the potential to be an effective and low-cost technique for selective nanoheteroepitaxial growth of CdTe films on Si(100) substrates for infrared detector applications.

  5. Growth and characterization of rutile TiO2 nanorods on various substrates with fabricated fast-response metal-semiconductor-metal UV detector based on Si substrate

    Science.gov (United States)

    Selman, Abbas M.; Hassan, Z.

    2015-07-01

    Rutile-phase titanium dioxide nanorods (NRs) were synthesized successfully on p-type silicon (Si) (1 1 1), c-plane sapphire (Al2O3), glass coated with fluorine-doped tin oxide (FTO), glass, and quartz substrates via chemical bath deposition method. All substrates were seeded with a TiO2 seed layer synthesized with a radio frequency reactive magnetron sputtering system prior to NRs growth. The effect of substrate type on structural, morphological, and optical properties of rutile TiO2 NRs was studied. X-ray diffraction, Raman spectroscopy, and field-emission scanning electron microscopy analyses showed the tetragonal rutile structure of the synthesized TiO2 NRs. Optical properties were examined with photoluminescence (PL) spectroscopy of the grown rutile NRs on all substrates, with the spectra exhibiting one strong ultraviolet emission peak intensity compared with broad visible peak. The optimal sample of rutile NRs was grown on Si substrate. Thus, a fast-response metal-semiconductor-metal ultraviolet (UV) detector was fabricated. Upon exposure to 365 nm light (2.3 mW/cm2) at 5 V bias, the device displays 2.62 × 10-5 A photocurrent, and the response and recovery times are calculated as 18.5 and 19.1 ms, respectively. These results demonstrate that the fabricated high-quality photodiode is a promising candidate as a low-cost UV photodetector for commercially integrated photoelectronic applications.

  6. Measurement of gamma-ray intensities of sup 2 sup 3 sup 1 Th using semiconductor detectors

    CERN Document Server

    Chatani, H

    1999-01-01

    Nuclide sup 2 sup 3 sup 1 Th was yielded by the sup 2 sup 3 sup 2 Th(n, 2n) reaction with neutron irradiation in the Kyoto University Reactor (KUR). Moreover, the thorium was purified chemically. Gamma-ray spectra of thorium have been measured using low-energy photon spectrometers and a high-purity germanium detector. Relative gamma-ray intensities ranging from 25 to 352 keV in the decay of sup 2 sup 3 sup 1 Th have been determined with satisfactory accuracy. The results are in very good agreement with those of earlier studies. We observe two new gamma-rays at 77.69 and 177.66 keV, whose intensities are found to be (0.063+-0.010)% and (0.00095+-0.00020)%, respectively, relative to that of 84.21 keV taken as 100%. Absolute intensity of 84.21 keV gamma-ray which is the most prominent one from the decay of sup 2 sup 3 sup 1 Th and that of 185.739 keV following the decay of sup 2 sup 3 sup 5 U are also determined from the secular equilibrium for sup 2 sup 3 sup 5 U- sup 2 sup 3 sup 1 Th. The results obtained in t...

  7. An upgraded drift–diffusion model for evaluating the carrier lifetimes in radiation-damaged semiconductor detectors

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Lopez, J., E-mail: fjgl@us.es [Dept of Atomic, Molecular and Nuclear Physics, University of Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain); CNA (U. Sevilla, J. Andalucia, CSIC), Av. Thomas A. Edison 7, 41092 Sevilla (Spain); Jimenez-Ramos, M.C.; Rodriguez-Ramos, M. [CNA (U. Sevilla, J. Andalucia, CSIC), Av. Thomas A. Edison 7, 41092 Sevilla (Spain); Forneris, J. [Physics Dept./NIS Centre, University of Torino, INFN-Sez. di Torino, via P. Giuria 1, 10125 Torino (Italy); Ceballos, J. [Institute of Microelectronics of Seville, IMSE-CNM (CSIC/University of Seville), Seville 41092 (Spain)

    2016-03-15

    The transport properties of a series of n- and p-type Si diodes have been studied by the ion beam induced charge (IBIC) technique using a 4 MeV proton microbeam. The samples were irradiated with 17 MeV protons at fluences ranging from 1 × 10{sup 12} to 1 × 10{sup 13} p/cm{sup 2} in order to produce a uniform profile of defects with depth. The analysis of the charge collection efficiency (CCE) as a function of the reverse bias voltage has been carried out using an upgraded drift–diffusion (D–D) model which takes into account the possibility of carrier recombination not only in the neutral substrate, as the simple D–D model assumes, but also within the depletion region. This new approach for calculating the CCE is fundamental when the drift length of carriers cannot be considered as much greater that the thickness of the detector due to the ion induced damage. From our simulations, we have obtained the values of the carrier lifetimes for the pristine and irradiated diodes, which have allowed us to calculate the effective trapping cross sections using the one dimension Shockley–Read–Hall model. The results of our calculations have been compared to the data obtained using a recently developed Monte Carlo code for the simulation of IBIC analysis, based on the probabilistic interpretation of the excess carrier continuity equations.

  8. Characterization of imaging pixel detectors of Si and CdTe read out with the counting X-ray chip MPEC 2.3; Charakterisierung von bildgebenden Pixeldetektoren aus Si und CdTe ausgelesen mit dem zaehlenden Roentgenchip MPEC 2.3

    Energy Technology Data Exchange (ETDEWEB)

    Loecker, M.

    2007-04-15

    Single photon counting detectors with Si- and CdTe-sensors have been constructed and characterized. As readout chip the MPEC 2.3 is used which consists of 32 x 32 pixels with 200 x 200 {mu}m{sup 2} pixel size and which has a high count rate cabability (1 MHz per pixel) as well as a low noise performance (55 e{sup -}). Measurements and simulations of the detector homogeneity are presented. It could be shown that the theoretical maximum of the homogeneity is reached (quantum limit). By means of the double threshold of the MPEC chip the image contrast can be enhanced which is demonstrated by measurement and simulation. Also, multi-chip-modules consisting of 4 MPEC chips and a single Si- or CdTe-sensor have been constructed and successfully operated. With these modules modulation-transfer-function measurements have been done showing a good spatial resolution of the detectors. In addition, multi-chip-modules according to the Sparse-CMOS concept have been built and tests characterizing the interconnection technologies have been performed.

  9. Advanced CdTe Photovoltaic Technology: September 2007 - March 2009

    Energy Technology Data Exchange (ETDEWEB)

    Barth, K.

    2011-05-01

    During the last eighteen months, Abound Solar (formerly AVA Solar) has enjoyed significant success under the SAI program. During this time, a fully automated manufacturing line has been developed, fabricated and commissioned in Longmont, Colorado. The facility is fully integrated, converting glass and semiconductor materials into complete modules beneath its roof. At capacity, a glass panel will enter the factory every 10 seconds and emerge as a completed module two hours later. This facility is currently undergoing trials in preparation for large volume production of 120 x 60 cm thin film CdTe modules. Preceding the development of the large volume manufacturing capability, Abound Solar demonstrated long duration processing with excellent materials utilization for the manufacture of high efficiency 42 cm square modules. Abound Solar prototype modules have been measured with over 9% aperture area efficiency by NREL. Abound Solar demonstrated the ability to produce modules at industry leading low costs to NREL representatives. Costing models show manufacturing costs below $1/Watt and capital equipment costs below $1.50 per watt of annual manufacturing capacity. Under this SAI program, Abound Solar supported a significant research and development program at Colorado State University. The CSU team continues to make progress on device and materials analysis. Modeling for increased device performance and the effects of processing conditions on properties of CdTe PV were investigated.

  10. Long Carrier Lifetimes in Large-Grain Polycrystalline CdTe Without CdCl2

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Soren A.; Burst, James M.; Duenow, Joel N.; Guthrey, Harvey L.; Moseley, John; Moutinho, Helio R.; Johnston, Steve W.; Kanevce, Ana; Al-Jassim, Mowafak M.; Metzger, Wyatt K.

    2016-06-27

    For decades, polycrystalline CdTe thin films for solar applications have been restricted to grain sizes of microns or less whereas other semiconductors such as silicon and perovskites have produced devices with grains ranging from less than a micron to more than 1 mm. Because the lifetimes in as-deposited polycrystalline CdTe films are typically limited to less than a few hundred picoseconds, a CdCl2 treatment is generally used to improve the lifetime; but this treatment may limit the achievable hole density by compensation. Here, we establish methods to produce CdTe films with grain sizes ranging from hundreds of nanometers to several hundred microns by close-spaced sublimation at industrial manufacturing growth rates. Two-photon excitation photoluminescence spectroscopy shows a positive correlation of lifetime with grain size. Large-grain, as-deposited CdTe exhibits lifetimes exceeding 10 ns without Cl, S, O, or Cu. This uncompensated material allows dopants such as P to achieve a hole density of 1016 cm-3, which is an order of magnitude higher than standard CdCl2-treated devices, without compromising the lifetime.

  11. Long carrier lifetimes in large-grain polycrystalline CdTe without CdCl2

    Science.gov (United States)

    Jensen, S. A.; Burst, J. M.; Duenow, J. N.; Guthrey, H. L.; Moseley, J.; Moutinho, H. R.; Johnston, S. W.; Kanevce, A.; Al-Jassim, M. M.; Metzger, W. K.

    2016-06-01

    For decades, polycrystalline CdTe thin films for solar applications have been restricted to grain sizes of microns or less whereas other semiconductors such as silicon and perovskites have produced devices with grains ranging from less than a micron to more than 1 mm. Because the lifetimes in as-deposited polycrystalline CdTe films are typically limited to less than a few hundred picoseconds, a CdCl2 treatment is generally used to improve the lifetime; but this treatment may limit the achievable hole density by compensation. Here, we establish methods to produce CdTe films with grain sizes ranging from hundreds of nanometers to several hundred microns by close-spaced sublimation at industrial manufacturing growth rates. Two-photon excitation photoluminescence spectroscopy shows a positive correlation of lifetime with grain size. Large-grain, as-deposited CdTe exhibits lifetimes exceeding 10 ns without Cl, S, O, or Cu. This uncompensated material allows dopants such as P to achieve a hole density of 1016 cm-3, which is an order of magnitude higher than standard CdCl2-treated devices, without compromising the lifetime.

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

    CERN Document Server

    Bellazzini, R; Brez, A; Minuti, M; Pinchera, M; Mozzo, P

    2012-01-01

    An innovative X-ray imaging sensor with intrinsic digital characteristics is presented. It is based on Chromatic Photon Counting technology. The detector is able to count individually the incident X-ray photons and to separate them according to their energy (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 high spatial resolution (more than 10 l.p./mm at MTF50) allow to obtain an optimal ratio between image quality and absorbed dose. The individual block of the imaging system is a two-side buttable semiconductor radiation detector made of a thin pixellated CdTe crystal (the sensor) coupled to a large area VLSI CMOS pixel ASIC. 1, 2, 4, 8 tile units have been built. The 8 tiles unit has 25cm x 2.5cm sensitive area. Results and images obtained from in depth testing of several configurations of the system are presented. The X-Ray imaging system is the technological platform of PIXIRAD Im...

  13. Semiconductor crystal high resolution imager

    Science.gov (United States)

    Levin, Craig S. (Inventor); Matteson, James (Inventor)

    2011-01-01

    A radiation imaging device (10). The radiation image device (10) comprises a subject radiation station (12) producing photon emissions (14), and at least one semiconductor crystal detector (16) arranged in an edge-on orientation with respect to the emitted photons (14) to directly receive the emitted photons (14) and produce a signal. The semiconductor crystal detector (16) comprises at least one anode and at least one cathode that produces the signal in response to the emitted photons (14).

  14. Physics of grain boundaries in polycrystalline photovoltaic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yanfa, E-mail: yanfa.yan@utoledo.edu; Yin, Wan-Jian; Wu, Yelong; Shi, Tingting; Paudel, Naba R. [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Ohio 43606 (United States); Li, Chen [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Poplawsky, Jonathan [The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Wang, Zhiwei [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Ohio 43606 (United States); National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Moseley, John; Guthrey, Harvey; Moutinho, Helio; Al-Jassim, Mowafak M. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Pennycook, Stephen J. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States)

    2015-03-21

    Thin-film solar cells based on polycrystalline Cu(In,Ga)Se{sub 2} (CIGS) and CdTe photovoltaic semiconductors have reached remarkable laboratory efficiencies. It is surprising that these thin-film polycrystalline solar cells can reach such high efficiencies despite containing a high density of grain boundaries (GBs), which would seem likely to be nonradiative recombination centers for photo-generated carriers. In this paper, we review our atomistic theoretical understanding of the physics of grain boundaries in CIGS and CdTe absorbers. We show that intrinsic GBs with dislocation cores exhibit deep gap states in both CIGS and CdTe. However, in each solar cell device, the GBs can be chemically modified to improve their photovoltaic properties. In CIGS cells, GBs are found to be Cu-rich and contain O impurities. Density-functional theory calculations reveal that such chemical changes within GBs can remove most of the unwanted gap states. In CdTe cells, GBs are found to contain a high concentration of Cl atoms. Cl atoms donate electrons, creating n-type GBs between p-type CdTe grains, forming local p-n-p junctions along GBs. This leads to enhanced current collections. Therefore, chemical modification of GBs allows for high efficiency polycrystalline CIGS and CdTe thin-film solar cells.

  15. Measurement of mobility and lifetime of electrons and holes in a Schottky CdTe diode

    OpenAIRE

    Ariño-Estrada, G.; Chmeissani, M.; De Lorenzo, G.; Kolstein, M.; Puigdengoles, C; García, J; Cabruja, E.

    2014-01-01

    We report on the measurement of drift properties of electrons and holes in a CdTe diode grown by the travelling heating method (THM). Mobility and lifetime of both charge carriers has been measured independently at room temperature and fixed bias voltage using charge integration readout electronics. Both electrode sides of the detector have been exposed to a 241Am source in order to obtain events with full contributions of either electrons or holes. The drift time has been measured to obtain ...

  16. Quantized Nanocrystalline CdTe Thin Films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nanocrystalline CdTe thin films were prepared by asymmetric rectangular pulse electrodeposition in organic solution at 110°C. STM image shows a porous network morphology constructed by interconnected spherical CdTe crystallites with a mean diameter of 4.2 nm. A pronounced size quantization was indicated in the action and absorption spectra. Potentials dependence dual conductive behavior was revealed in the photocurrent-potential (I-V) curves.

  17. Identification of critical stacking faults in thin-film CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Su-Hyun; Walsh, Aron, E-mail: a.walsh@bath.ac.uk [Global E3 Institute, Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom); Butler, Keith T. [Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom); Soon, Aloysius [Global E3 Institute, Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Abbas, Ali; Walls, John M., E-mail: j.m.wall@loughborough.ac.uk [Centre for Renewable Energy Systems Technology, School of Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2014-08-11

    Cadmium telluride (CdTe) is a p-type semiconductor used in thin-film solar cells. To achieve high light-to-electricity conversion, annealing in the presence of CdCl{sub 2} is essential, but the underlying mechanism is still under debate. Recent evidence suggests that a reduction in the high density of stacking faults in the CdTe grains is a key process that occurs during the chemical treatment. A range of stacking faults, including intrinsic, extrinsic, and twin boundary, are computationally investigated to identify the extended defects that limit performance. The low-energy faults are found to be electrically benign, while a number of higher energy faults, consistent with atomic-resolution micrographs, are predicted to be hole traps with fluctuations in the local electrostatic potential. It is expected that stacking faults will also be important for other thin-film photovoltaic technologies.

  18. Evaluation of clinical use of OneDose™ metal oxide semiconductor field-effect transistor detectors compared to thermoluminescent dosimeters to measure skin dose for adult patients with acute lymphoblastic leukemia

    Directory of Open Access Journals (Sweden)

    Huda Ibrahim Al-Mohammed

    2011-01-01

    Full Text Available Background: Total body irradiation is a protocol used to treat acute lymphoblastic leukemia in patients prior to their bone marrow transplant. It involves the treatment of the whole body using a large radiation field with extended source-skin distance. Therefore, it is important to measure and monitor the skin dose during the treatment. Thermoluminescent dosimeters (TLDs and the OneDose™ metal oxide semiconductor field effect transistor (MOSFET detectors are used during treatment delivery to measure the radiation dose and compare it with the target prescribed dose. Aims: The primary goal of this study was to measure the variation of skin dose using OneDose MOSFET detectors and TLD detectors, and compare the results with the target prescribed dose. The secondary aim was to evaluate the simplicity of use and determine if one system was superior to the other in clinical use. Material and Methods : The measurements involved twelve adult patients diagnosed with acute lymphoblastic leukemia. TLD and OneDose MOSFET dosimetry were performed at ten different anatomical sites of each patient. Results : The results showed that there was a variation between skin dose measured with OneDose MOSFET detectors and TLD in all patients. However, the variation was not significant. Furthermore, the results showed for every anatomical site there was no significant different between the prescribed dose and the dose measured by either TLD or OneDose MOSFET detectors. Conclusion: There were no significant differences between the OneDose MOSFET and TLDs in comparison to the target prescribed dose. However, OneDose MOSFET detectors give a direct read-out immediately after the treatment, and their simplicity of use to compare with TLD detectors may make them preferred for clinical use.

  19. Performance evaluation of a small CZT pixelated semiconductor gamma camera system with a newly designed stack-up parallel-hole collimator

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngjin [Department of Radiological Science, College of Health Science, Eulji University, 553 Sanseong-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do 461-713 (Korea, Republic of); Kim, Hee-Joung, E-mail: hjk1@yonsei.ac.kr [Department of Radiological Science, College of Health Science, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 220-710 (Korea, Republic of)

    2015-09-11

    Gamma ray imaging techniques that use a cadmium zinc telluride (CZT) or cadmium telluride (CdTe) pixelated semiconductor detectors have rapidly gained popularity as a key tool for nuclear medicine research. By using a pinhole collimator with a pixelated semiconductor gamma camera system, better spatial resolution can be achieved. However, this improvement in spatial resolution is accomplished with a decrease in the sensitivity due to the small collimator hole diameter. Furthermore, few studies have been conducted for novel parallel-hole collimator geometric designs with pixelated semiconductor gamma camera systems. A gamma camera system which combines a CZT pixelated semiconductor detector with a newly designed stack-up parallel-hole collimator was developed and evaluated. The eValuator-2500 CZT pixelated semiconductor detector (eV product, Saxonburg, PA) was selected for the gamma camera system. This detector consisted of a row of four CZT crystals of 12.8 mm in length with 3 mm in thickness. The proposed parallel-hole collimator consists of two layers. The upper layer results in a fourfold increase in hole size compared to a matched square hole parallel-hole collimator with an equal hole and pixel size, while the lower layer also consisted of fourfold holes size and pretty acts as a matched square hole parallel-hole collimator. The overlap ratios of these collimators were 1:1, 1:2, 2:1, 1:5, and 5:1. These collimators were mounted on the eValuator-2500 CZT pixelated semiconductor detector. The basic performance of the imaging system was measured for a {sup 57}Co gamma source (122 keV). The measured averages of sensitivity and spatial resolution varied depending on the overlap ratios of the proposed parallel-hole collimator and source-to-collimator distances. One advantage of our system is the use of stacked collimators that can select the best combination of system sensitivity and spatial resolution. With low counts, we can select a high sensitivity collimator

  20. Detectors - Electronics; Detecteurs - Electronique

    Energy Technology Data Exchange (ETDEWEB)

    Bregeault, J.; Gabriel, J.L.; Hierle, G.; Lebotlan, P.; Leconte, A.; Lelandais, J.; Mosrin, P.; Munsch, P.; Saur, H.; Tillier, J. [Lab. de Physique Corpusculaire, Caen Univ., 14 (France)

    1998-04-01

    The reports presents the main results obtained in the fields of radiation detectors and associated electronics. In the domain of X-ray gas detectors for the keV range efforts were undertaken to rise the detector efficiency. Multiple gap parallel plate chambers of different types as well as different types of X {yields} e{sup -} converters were tested to improve the efficiency (values of 2.4% at 60 KeV were reached). In the field of scintillators a study of new crystals has been carried out (among which Lutetium orthosilicate). CdTe diode strips for obtaining X-ray imaging were studied. The complete study of a linear array of 8 CdTe pixels has been performed and certified. The results are encouraging and point to this method as a satisfying solution. Also, a large dimension programmable chamber was used to study the influence of temperature on the inorganic scintillators in an interval from -40 deg. C to +150 deg. C. Temperature effects on other detectors and electronic circuits were also investigated. In the report mentioned is also the work carried out for the realization of the DEMON neutron multidetector. For neutron halo experiments different large area Si detectors associated with solid and gas position detectors were realized. In the frame of a contract with COGEMA a systematic study of Li doped glasses was undertaken aiming at replacing with a neutron probe the {sup 3}He counters presently utilized in pollution monitoring. An industrial prototype has been realised. Other studies were related to integrated analog chains, materials for Cherenkov detectors, scintillation probes for experiments on fundamental processes, gas position sensitive detectors, etc. In the field of associated electronics there are mentioned the works related to the multidetector INDRA, data acquisition, software gamma spectrometry, automatic gas pressure regulation in detectors, etc

  1. Ion implantation of CdTe single crystals

    Directory of Open Access Journals (Sweden)

    Wiecek Tomasz

    2017-01-01

    Full Text Available Ion implantation is a technique which is widely used in industry for unique modification of metal surface for medical applications. In semiconductor silicon technology ion implantation is also widely used for thin layer electronic or optoelectronic devices production. For other semiconductor materials this technique is still at an early stage. In this paper based on literature data we present the main features of the implantation of CdTe single crystals as well as some of the major problems which are likely to occur when dealing with them. The most unexpected feature is the high resistance of these crystals against the amorphization caused by ion implantation even at high doses (1017 1/cm2. The second property is the disposal of defects much deeper in the sample then it follows from the modeling calculations. The outline of principles of the ion implantation is included in the paper. The data based on RBS measurements and modeling results obtained by using SRIM software were taken into account.

  2. Ion implantation of CdTe single crystals

    Science.gov (United States)

    Wiecek, Tomasz; Popovich, Volodymir; Bester, Mariusz; Kuzma, Marian

    2016-12-01

    Ion implantation is a technique which is widely used in industry for unique modification of metal surface for medical applications. In semiconductor silicon technology ion implantation is also widely used for thin layer electronic or optoelectronic devices production. For other semiconductor materials this technique is still at an early stage. In this paper based on literature data we present the main features of the implantation of CdTe single crystals as well as some of the major problems which are likely to occur when dealing with them. The most unexpected feature is the high resistance of these crystals against the amorphization caused by ion implantation even at high doses (1017 1/cm2). The second property is the disposal of defects much deeper in the sample then it follows from the modeling calculations. The outline of principles of the ion implantation is included in the paper. The data based on RBS measurements and modeling results obtained by using SRIM software were taken into account.

  3. Low noise CMOS readout for CdZnTe detector arrays

    CERN Document Server

    Jakobson, C G; Lev, S B; Nemirovsky, Y

    1999-01-01

    A low noise CMOS readout for CdTe and CdZnTe X- and gamma-ray detector arrays has been designed and implemented in the CMOS 2 mu m low noise analog process provided by the multi-chip program of Metal Oxide Semiconductor Implementation Service. The readout includes CMOS low noise charge sensitive preamplifier and a multiplexed semi-Gaussian pulse shaper. Thus, each detector has a dedicated charge sensitive preamplifier that integrates its signal, while a single shaping amplifier shapes the pulses after the multiplexer. Low noise and low-power operation are achieved by optimizing the input transistor of the charge sensitive preamplifier. Two optimization criteria are used to reduce noise. The first criterion is based on capacitance matching between the input transistor and the detector. The second criterion is based on bandwidth optimization, which is obtained by tailoring the shaper parameters to the particular noise mechanisms of the MOS transistor and the CdZnTe detector. Furthermore, the multiplexing functi...

  4. Thickness-Controllable Silica Coating of CdTe QDs by Reverse Microemulsion Method for the Application in the Growth of Rice

    Directory of Open Access Journals (Sweden)

    Aiwu Wang

    2014-01-01

    Full Text Available Herein, we report the synthesis and surface modification of CdTe quantum dots (QDs and the application in the rice growth. Water-soluble thioglycolic acid (TGA stabilized CdTe quantum dots were synthesized firstly and then the surface modification was conducted. II–VI semiconductor nanocrystals prefer to be coated with silica as inert materials to improve their chemical properties. The toxicity of QDs reduced after the modification. Silica coated QDs were used in the growth of rice seed and the effect was discussed. In our knowledge it is the first time we report that the silica coated QDs had nice effect on the growth of rice.

  5. High-resolution Compton cameras based on Si/CdTe double-sided strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Odaka, Hirokazu, E-mail: odaka@astro.isas.jaxa.jp [Department of High Energy Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Ichinohe, Yuto [Department of High Energy Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Department of Physics, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033 (Japan); Takeda, Shin' ichiro [Department of High Energy Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Fukuyama, Taro; Hagino, Koichi; Saito, Shinya; Sato, Tamotsu [Department of High Energy Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Department of Physics, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033 (Japan); Sato, Goro; Watanabe, Shin; Kokubun, Motohide [Department of High Energy Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Takahashi, Tadayuki [Department of High Energy Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Department of Physics, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033 (Japan); Yamaguchi, Mitsutaka [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency (JAEA), 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); and others

    2012-12-11

    We have developed a new Compton camera based on silicon (Si) and cadmium telluride (CdTe) semiconductor double-sided strip detectors (DSDs). The camera consists of a 500-{mu}m-thick Si-DSD and four layers of 750-{mu}m-thick CdTe-DSDs all of which have common electrode configuration segmented into 128 strips on each side with pitches of 250{mu}m. In order to realize high angular resolution and to reduce size of the detector system, a stack of DSDs with short stack pitches of 4 mm is utilized to make the camera. Taking advantage of the excellent energy and position resolutions of the semiconductor devices, the camera achieves high angular resolutions of 4.5 Degree-Sign at 356 keV and 3.5 Degree-Sign at 662 keV. To obtain such high resolutions together with an acceptable detection efficiency, we demonstrate data reduction methods including energy calibration using Compton scattering continuum and depth sensing in the CdTe-DSD. We also discuss imaging capability of the camera and show simultaneous multi-energy imaging.

  6. Soft Gamma-ray Detector for the ASTRO-H Mission

    CERN Document Server

    Tajima, Hiroyasu; Enoto, Teruaki; Fukazawa, Yasushi; Gilmore, Kirk; Kamae, Tuneyoshi; Kataoka, Jun; Kawaharada, Madoka; Kokubun, Motohide; Laurent, Philippe; Lebrun, Francois; Limousin, Olivier; Madejski, Greg; Makishima, Kazuo; Mizuno, Tsunefumi; Nakazawa, Kazuhiro; Ohno, Masanori; Ohta, Masayuki; Sato, Goro; Sato, Rie; Takahashi, Hiromitsu; Takahashi, Tadayuki; Tanaka, Takaaki; Tashiro, Makoto; Terada, Yukikatsu; Uchiyama, Yasunobu; Watanabe, Shin; Yamaoka, Kazutaka; Yonetoku, Daisuke; 10.1117/12.857531

    2010-01-01

    ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage and exquisite energy resolution. The Soft Gamma-ray Detector (SGD) is one of ASTRO-H instruments and will feature wide energy band (40-600 keV) at a background level 10 times better than the current instruments on orbit. SGD is complimentary to ASTRO-H's Hard X-ray Imager covering the energy range of 5-80 keV. The SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield where Compton kinematics is utilized to reject backgrounds. The Compton camera in the SGD is realized as a hybrid semiconductor detector system which consists of silicon and CdTe (cadmium telluride) sensors. Good energy resolution is afforded by semiconductor sensors, and it results in good background rejection capability due to better constraints on Compton kinematics. Utilization of Compton kinematics also makes the SGD sensitive to the gamma-ray polarization, opening up a new window ...

  7. Hybrid Pixel Detectors for gamma/X-ray imaging

    Science.gov (United States)

    Hatzistratis, D.; Theodoratos, G.; Zografos, V.; Kazas, I.; Loukas, D.; Lambropoulos, C. P.

    2015-09-01

    Hybrid pixel detectors are made by direct converting high-Z semi-insulating single crystalline material coupled to complementary-metal-oxide semiconductor (CMOS) readout electronics. They are attractive because direct conversion exterminates all the problems of spatial localization related to light diffusion, energy resolution, is far superior from the combination of scintillation crystals and photomultipliers and lithography can be used to pattern electrodes with very fine pitch. We are developing 2-D pixel CMOS ASICs, connect them to pixilated CdTe crystals with the flip chip and bump bonding method and characterize the hybrids. We have designed a series of circuits, whose latest member consists of a 50×25 pixel array with 400um pitch and an embedded controller. In every pixel a full spectroscopic channel with time tagging information has been implemented. The detectors are targeting Compton scatter imaging and they can be used for coded aperture imaging too. Hybridization using CMOS can overcome the limit put on pixel circuit complexity by the use of thin film transistors (TFT) in large flat panels. Hybrid active pixel sensors are used in dental imaging and other applications (e.g. industrial CT etc.). Thus X-ray imaging can benefit from the work done on dynamic range enhancement methods developed initially for visible and infrared CMOS pixel sensors. A 2-D CMOS ASIC with 100um pixel pitch to demonstrate the feasibility of such methods in the context of X-ray imaging has been designed.

  8. CdTe Quantum Dot/Dye Hybrid System as Photosensitizer for Photodynamic Therapy

    Science.gov (United States)

    Rakovich, Aliaksandra; Savateeva, Diana; Rakovich, Tatsiana; Donegan, John F.; Rakovich, Yury P.; Kelly, Vincent; Lesnyak, Vladimir; Eychmüller, Alexander

    2010-04-01

    We have studied the photodynamic properties of novel CdTe quantum dots—methylene blue hybrid photosensitizer. Absorption spectroscopy, photoluminescence spectroscopy, and fluorescence lifetime imaging of this system reveal efficient charge transfer between nanocrystals and the methylene blue dye. Near-infrared photoluminescence measurements provide evidence for an increased efficiency of singlet oxygen production by the methylene blue dye. In vitro studies on the growth of HepG2 and HeLa cancerous cells were also performed, they point toward an improvement in the cell kill efficiency for the methylene blue-semiconductor nanocrystals hybrid system.

  9. 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

  10. RF magnetron sputtering deposition of CdTe passivation on HgCdTe

    Science.gov (United States)

    Rutkowski, Jaroslaw; Adamiec, Krzysztof; Rogalski, Antoni

    1998-04-01

    In this study, we report the RF magnetron sputtering growth and characterization of CdTe passivant on bulk n-type HgCdTe. Our investigations include the HgCdTe surface preparation and in-situ pretreatment, deposition-induced surface damage, interface charge, CdTe film stoichiometry, and thermal stability. The metal-insulator-semiconductor test structures are processed and their electrical properties are measured by capacitance-voltage characteristics. The heterostructures are also characterized by reflectance measurement. In order to investigate the passivation properties of CdTe/HgCdTe heterostructures, we have modeled the band diagram of abrupt CdTe/HgCdTe heterojunction. The effect of sputtering growth condition parameters is also reported. The sputtering CdTe layers, exhibit excellent dielectric, insulating and mechano- chemical properties, as well as interface properties. The interfaces are characterized by slight accumulation and a small hysteresis. A carefully controlled growth process and surface pretreatment tailored to the specific material are required in order to obtain near flat band conditions on n- type materials. Additional informations on surface limitations are obtained from analyzing the I-V characteristics of photodiodes with metal gates covering the p-n junction surface location.

  11. Microscopic partition of pressure and elastic constants in CdTe polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Ouahrani, T. [Laboratoire de Physique Théorique, Tlemcen University, 13000 Tlemcen (Algeria); École Préparatoire en Sciences et Techniques, 13000 Tlemcen (Algeria); Franco, R.; Menéndez, J.M.; Marqués, M. [MALTA Team and Departamento de Química Física y Analítica, Universidad de Oviedo, E-33006 Oviedo (Spain); Recio, J.M., E-mail: jmrecio@uniovi.es [MALTA Team and Departamento de Química Física y Analítica, Universidad de Oviedo, E-33006 Oviedo (Spain)

    2014-04-01

    Highlights: • Pressure ranges of stability of CdTe polymorphs are successfully computed. • A cubic B2 phase is predicted at pressures above 70 GPa. • Microscopic pressures are defined without resorting to energy partitions. • Cd shows a greater mechanical resistance than Te when pressure is applied. • Atomic equations of state are proposed for Cd and Te along the polymorphic sequence. - Abstract: Within the framework of density functional theory, first principles calculations were carried out to determine pressure stability ranges of zinc-blende (B3), cinnabar (Cinn), rock-salt (B1), orthorhombic (Cmcm), and cesium chloride (B2) phases of CdTe. In agreement with experimental observations, we found a B3→Cinn→B1→Cmcm pressure-induced sequence, and predict the B2 phase as a potential high pressure polymorph. The equations of state of all these polymorphs and the components of the elasticity tensor of the B3 phase at zero pressure were determined and microscopically analyzed in terms of atomic contributions. The concept of local pressure allows for quantifying differences in the role played by Cd and Te as regards the compressibility of CdTe phases, and suggests the existence of a general behavior under pressure for binary II–VI semiconductors.

  12. CdTe quantum dots@luminol as signal amplification system for chrysoidine with chemiluminescence-chitosan/graphene oxide-magnetite-molecularly imprinting sensor.

    Science.gov (United States)

    Duan, Huimin; Li, Leilei; Wang, Xiaojiao; Wang, Yanhui; Li, Jianbo; Luo, Chuannan

    2016-01-15

    A sensitive chemiluminescence (CL) sensor based on chemiluminescence resonance energy transfer (CRET) in CdTe quantum dots@luminol (CdTe QDs@luminol) nanomaterials combined with chitosan/graphene oxide-magnetite-molecularly imprinted polymer (Cs/GM-MIP) for sensing chrysoidine was developed. CdTe QDs@luminol was designed to not only amplify the signal of CL but also reduce luminol consumption in the detection of chrysoidine. On the basis of the abundant hydroxy and amino, Cs and graphene oxide were introduced into the GM-MIP to improve the adsorption ability. The adsorption capacities of chrysoidine by both Cs/GM-MIP and non-imprinted polymer (Cs/GM-NIP) were investigated, and the CdTe QDs@luminol and Cs/GM-MIP were characterized by UV-vis, FTIR, SEM and TEM. The proposed sensor can detect chrysoidine within a linear range of 1.0×10(-7) - 1.0×10(-5) mol/L with a detection limit of 3.2×10(-8) mol/L (3δ) due to considerable chemiluminescence signal enhancement of the CdTe quantum dots@luminol detector and the high selectivity of the Cs/GM-MIP system. Under the optimal conditions of CL, the CdTe QDs@luminol-Cs/GM-MIP-CL sensor was used for chrysoidine determination in samples with satisfactory recoveries in the range of 90-107%.

  13. Pixel detectors

    CERN Document Server

    Passmore, M S

    2001-01-01

    positions on the detector. The loss of secondary electrons follows the profile of the detector and increases with higher energy ions. studies of the spatial resolution predict a value of 5.3 lp/mm. The image noise in photon counting systems is investigated theoretically and experimentally and is shown to be given by Poisson statistics. The rate capability of the LAD1 was measured to be 250 kHz per pixel. Theoretical and experimental studies of the difference in contrast for ideal charge integrating and photon counting imaging systems were carried out. It is shown that the contrast differs and that for the conventional definition (contrast = (background - signal)/background) the photon counting device will, in some cases, always give a better contrast than the integrating system. Simulations in MEDICI are combined with analytical calculations to investigate charge collection efficiencies (CCE) in semiconductor detectors. Different pixel sizes and biasing conditions are considered. The results show charge shari...

  14. Photo-induced interaction of thioglycolic acid (TGA)-capped CdTe quantum dots with cyanine dyes

    Science.gov (United States)

    Abdelbar, Mostafa F.; Fayed, Tarek A.; Meaz, Talaat M.; Ebeid, El-Zeiny M.

    2016-11-01

    The photo-induced interaction of three different sizes of thioglycolic acid (TGA)-capped CdTe quantum dots (CdTe QDs) with two monomethine cyanine dyes belonging to the thiazole orange (TO) family has been studied. Positively charged cyanines interact with QDs surface which is negatively charged due to capping agent carboxylate ions. The energy transfer parameters including Stern-Volmer constant, Ksv, number of binding sites, n, quenching sphere radius, r, the critical energy transfer distance, R0, and energy transfer efficiencies, E have been calculated. The effect of structure and the number of aggregating molecules have been studied as a function of CdTe QDs particle size. Combining organic and inorganic semiconductors leads to increase of the effective absorption cross section of the QDs which can be utilized in novel nanoscale designs for light-emitting, photovoltaic and sensor applications. A synthesized triplet emission of the studied dyes was observed using CdTe QDs as donors and this is expected to play a potential role in molecular oxygen sensitization and in photodynamic therapy (PDT) applications.

  15. WE-G-204-04: Focal Spot Deblurring For High Resolution Amorphous Selenium (aSe) Complementary Metal Oxide Semiconductor (CMOS) X-Ray Detector

    Energy Technology Data Exchange (ETDEWEB)

    Nagesh, S Setlur; Rana, R; Russ, M; Ionita, C; Bednarek, D; Rudin, S [Toshiba Stroke and Vascular Research Center, University at Buffalo, SUNY (United States)

    2015-06-15

    Purpose: CMOS-based aSe detectors compared to CsI-TFT-based flat panels have the advantages of higher spatial sampling due to smaller pixel size and decreased blurring characteristic of direct rather than indirect detection. For systems with such detectors, the limiting factor degrading image resolution then becomes the focal-spot geometric unsharpness. This effect can seriously limit the use of such detectors in areas such as cone beam computed tomography, clinical fluoroscopy and angiography. In this work a technique to remove the effect of focal-spot blur is presented for a simulated aSe detector. Method: To simulate images from an aSe detector affected with focal-spot blur, first a set of high-resolution images of a stent (FRED from Microvention, Inc.) were acquired using a 75µm pixel size Dexela-Perkin-Elmer detector and averaged to reduce quantum noise. Then the averaged image was blurred with a known Gaussian blur at two different magnifications to simulate an idealized focal spot. The blurred images were then deconvolved with a set of different Gaussian blurs to remove the effect of focal-spot blurring using a threshold-based, inverse-filtering method. Results: The blur was removed by deconvolving the images using a set of Gaussian functions for both magnifications. Selecting the correct function resulted in an image close to the original; however, selection of too wide a function would cause severe artifacts. Conclusion: Experimentally, focal-spot blur at different magnifications can be measured using a pin hole with a high resolution detector. This spread function can be used to deblur the input images that are acquired at corresponding magnifications to correct for the focal spot blur. For CBCT applications, the magnification of specific objects can be obtained using initial reconstructions then corrected for focal-spot blurring to improve resolution. Similarly, if object magnification can be determined such correction may be applied in fluoroscopy and

  16. Measurement and Modeling of Blocking Contacts for Cadmium Telluride Gamma Ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Patrick R. [California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States)

    2010-01-07

    Gamma ray detectors are important in national security applications, medicine, and astronomy. Semiconductor materials with high density and atomic number, such as Cadmium Telluride (CdTe), offer a small device footprint, but their performance is limited by noise at room temperature; however, improved device design can decrease detector noise by reducing leakage current. This thesis characterizes and models two unique Schottky devices: one with an argon ion sputter etch before Schottky contact deposition and one without. Analysis of current versus voltage characteristics shows that thermionic emission alone does not describe these devices. This analysis points to reverse bias generation current or leakage through an inhomogeneous barrier. Modeling the devices in reverse bias with thermionic field emission and a leaky Schottky barrier yields good agreement with measurements. Also numerical modeling with a finite-element physics-based simulator suggests that reverse bias current is a combination of thermionic emission and generation. This thesis proposes further experiments to determine the correct model for reverse bias conduction. Understanding conduction mechanisms in these devices will help develop more reproducible contacts, reduce leakage current, and ultimately improve detector performance.

  17. Development of TiBr semiconductor crystal for applications as radiation detector and photodetector; Desenvolvimento do cristal semicondutor de brometo de talio para aplicacoes como detector de radiacao e fotodetector

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Icimone Braga de

    2006-07-01

    In this work, Tlbr crystals were grown by the Bridgman method from zone melted materials. The influence of the purification efficiency and the crystalline surface quality on the crystal were studied, evaluating its performance as a radiation detector. Due to significant improvement in the purification and crystals growth, good results have been obtained for the developed detectors. The spectrometric performance of the Tlbr detector was evaluated by {sup 241}Am (59 keV), {sup 133}Ba (80 e 355 keV), {sup 57}Co (122 keV), {sup 22}Na (511 keV) and {sup 137} Cs (662 keV) at room temperature. The best energy resolution results were obtained from purer detectors. Energy resolutions of 10 keV (16%), 12 keV (15%), 12 keV (10%), 28 keV (8%), 31 keV (6%) and 36 keV (5%) to 59, 80, 122, 355, 511 and 662 keV energies, respectively, were obtained. A study on the detection response at -20 deg C was also carried out, as well as the detector stability in function of the time. No significant difference was observed in the energy resolution between measurements at both temperatures. It was observed that the detector instability causes degradation of the spectroscopic characteristics during measurements at room temperature and the instability varies for each detector. This behavior was also verified by other authors. The viability to use the developed Tlbr crystal as a photodetector coupled to scintillators crystals was also studied in this work. Due to its quantum efficiency in the region from 350 to 500 nm, Tlbr shows to be a promising material to be used as a photodetector. As a possible application of this work, the development of a surgical probe has been initiated using the developed Tlbr crystal as the radiation detector of the probe. (author)

  18. 14% sputtered thin-film solar cells based on CdTe

    Science.gov (United States)

    Compaan, A. D.; Gupta, A.; Drayton, J.; Lee, S.-H.; Wang, S.

    2004-02-01

    Polycrystalline II-VI semiconductor materials show great promise for thin-film photovoltaic cells and modules. Large-area deposition of these II-VI semiconductors such as CdTe is possible by a variety of methods but the use of a plasma-based method such as magnetron sputtering can have significant advantages. Here we present recent results in the fabrication of CdS/CdTe cells using rf magnetron sputtering and discuss some of the advantages that appear possible from the use of sputtering methods in this class of materials. Some of these advantages are particularly relevant as the polycrystalline thin-film PV community addresses issues related to the challenges of fabricating high efficiency tandem cells with efficiencies over 25%. Our best results have been obtained with sputtered ZnO:Al to achieve a CdTe solar cell with 14.0% efficiency at one sun for an air-mass-1.5 global spectrum. In addition, we have studied reactive sputtering of ZnTe:N which shows promise for use as a transparent back contact or recombination junction for alloyed II-VI-based top cells in a tandem solar-cell configuration.

  19. Semiconductor nanocrystals photosensitize C60 crystals.

    Science.gov (United States)

    Biebersdorf, Andreas; Dietmüller, Roland; Susha, Andrei S; Rogach, Andrey L; Poznyak, Sergey K; Talapin, Dmitri V; Weller, Horst; Klar, Thomas A; Feldmann, Jochen

    2006-07-01

    Semiconductor nanocrystals (SCNCs) made of CdSe, CdTe, and InP are used to photosensitize needlelike C(60) crystals. The photocurrent is increased by up to 3 orders of magnitude as compared with C(60) crystals without SCNCs. The photocurrent spectrum can be tuned precisely by the SCNC size and material, rendering the SCNC-functionalized C(60) crystals an excellent material for spectrally tuneable photodetectors. We explain the increased photocurrent as a result of photoexcited electrons transferring from the SCNCs to the C(60) crystals and causing photoconductivity, while the complementary holes remain trapped in the SCNCs.

  20. Investigating the effect of characteristic x-rays in cadmium zinc telluride detectors under breast computerized tomography operating conditions.

    Science.gov (United States)

    Glick, Stephen J; Didier, Clay

    2013-10-14

    A number of research groups have been investigating the use of dedicated breast computerized tomography (CT). Preliminary results have been encouraging, suggesting an improved visualization of masses on breast CT as compared to conventional mammography. Nonetheless, there are many challenges to overcome before breast CT can become a routine clinical reality. One potential improvement over current breast CT prototypes would be the use of photon counting detectors with cadmium zinc telluride (CZT) (or CdTe) semiconductor material. These detectors can operate at room temperature and provide high detection efficiency and the capability of multi-energy imaging; however, one factor in particular that limits image quality is the emission of characteristic x-rays. In this study, the degradative effects of characteristic x-rays are examined when using a CZT detector under breast CT operating conditions. Monte Carlo simulation software was used to evaluate the effect of characteristic x-rays and the detector element size on spatial and spectral resolution for a CZT detector used under breast CT operating conditions. In particular, lower kVp spectra and thinner CZT thicknesses were studied than that typically used with CZT based conventional CT detectors. In addition, the effect of characteristic x-rays on the accuracy of material decomposition in spectral CT imaging was explored. It was observed that when imaging with 50-60 kVp spectra, the x-ray transmission through CZT was very low for all detector thicknesses studied (0.5-3.0 mm), thus retaining dose efficiency. As expected, characteristic x-ray escape from the detector element of x-ray interaction increased with decreasing detector element size, approaching a 50% escape fraction for a 100 μm size detector element. The detector point spread function was observed to have only minor degradation with detector element size greater than 200 μm and lower kV settings. Characteristic x-rays produced increasing distortion

  1. Emission switching in carbon dots coated CdTe quantum dots driving by pH dependent hetero-interactions

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Xiao; Wang, Hao; Yi, Qinghua; Wang, Yun; Cong, Shan; Zhao, Jie; Sun, Yinghui; Zou, Guifu, E-mail: zouguifu@suda.edu.cn, E-mail: jiexiong@uestc.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Qian, Zhicheng [School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Huang, Jianwen; Xiong, Jie, E-mail: zouguifu@suda.edu.cn, E-mail: jiexiong@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Luo, Hongmei [Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, New Mexico 88003 (United States)

    2015-11-16

    Due to the different emission mechanism between fluorescent carbon dots and semiconductor quantum dots (QDs), it is of interest to explore the potential emission in hetero-structured carbon dots/semiconducting QDs. Herein, we design carbon dots coated CdTe QDs (CDQDs) and investigate their inherent emission. We demonstrate switchable emission for the hetero-interactions of the CDQDs. Optical analyses indicate electron transfer between the carbon dots and the CdTe QDs. A heterojunction electron process is proposed as the driving mechanism based on N atom protonation of the carbon dots. This work advances our understanding of the interaction mechanism of the heterostructured CDQDs and benefits the future development of optoelectronic nanodevices with new functionalities.

  2. CdTe reflection anisotropy line shape fitting

    Energy Technology Data Exchange (ETDEWEB)

    Molina-Contreras, J.R., E-mail: rmolina@correo.ita.mx [Departamento de Ingenieria Electrica y Electronica, Instituto Tecnologico de Aguascalientes, Av. Lopez Mateos 1801 Ote. Fracc. Bona Gens, Aguascalientes, Ags, 20256 (Mexico)

    2010-10-25

    In this paper, an empirical novel plane-wave time dependent ensemble is introduced to fit the RA, the reflectance (R) and the imaginary part of the dielectric function oscillation measured around the E{sub 1} and E{sub 1} + {Delta}{sub 1} transition region in II-VI semiconductors. By applying the new plane-wave time dependent ensemble to the measured spectrum for a (0 0 1) oriented CdTe undoped commercial wafer, crystallized in a zinc-blende structure, a very good agreement was found between the measured spectrum and the fitting. In addition to this, the reliability of the plane-wave time dependent ensemble was probed, by comparing the results with the calculated fitting in terms of a Fourier series and in terms of a six-order polynomial fit. Our analysis suggests, that the experimental oscillation in the line shape of the RA cannot be fitted with a Fourier series using harmonics multiples of the number which dominates the measured RA spectra in the argument of the plane-wave ensemble.

  3. CdTe Films Deposited by Closed-space Sublimation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    CdTe films are prepared by closed-space sublimation technology. Dependence of film crystalline on substrate materials and substrate temperature is investigated. It is found that films exhibit higher crystallinity at substrate temperature higher than 400℃. And the CdTe films deposited on CdS films with higher crystallinity have bigger crystallite and higher uniformity. Treatment with CdCl2 methanol solution promotes the crystallite growth of CdTe films during annealing.

  4. Synthesis and Surface Modification of CdTe Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CdTe nanocrystals were prepared in aqueous solution via the reaction between Cd2+ and NaHTe in the presence of mercaptoacetic acid. Interactions between CdTe nanocrystals and phenylalanine were formed via electrostatic/coordinate self-assembly. The photoluminescence intensity of CdTe nanocrystals was improved obviously. The interaction mechanism was discussed and was considered to be surface passivation.

  5. Study and development of new CdTe and CdZnTe detection structures for X and {gamma} imagery; Etude et realisation de nouvelles structures de detection a base de CdTe et CdZnTe pour l`imagerie X et {gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Rosaz, M

    1997-10-24

    The aim of this study is to show the interest of applying cadmium telluride (CdTe) for X- and {gamma}- ray imaging applications, with specific technological (via contact nature) and geometric (via Frisch grids) structures suited for each application. This work is divided into three different but complementary parts: the first part describes a simulation model which allows a better understanding of CdTe based {gamma}- ray detectors. The new feature of this model compared to previous ones, is that it is able to take into account the electric field`s non uniform spatial distribution inside the detector s. The results enable us to de-convolute the influence of material and contact parameters on the spectrometric performances (energy resolution and peak/valley ratio) of CdTe based detectors; the second part presents different technological structures deposited upon CdTe, (grown by two different methods, i.e Bridgman and High Pressure Bridgman). These structures were characterised in X- and {gamma}- ray detection; theoretical models are developed which allow a certain insight into the detection properties of each couple (material + contact); the third part deals with new contact geometries which allow a screening effect of the bulk (analogous to the Frisch grid effect in gaseous detectors) resulting in improved energy resolution and peak/valley ratios; encouraging first results on prototypes are presented and discussed. This work has allowed a better understanding of physical behaviour of CdTe based detectors, coupled with advances in technological issues to upgrade the overall performances of these detectors for application in X- and {gamma}- ray imaging. (author) 93 refs.

  6. Automatic Control System for the High Pressure CdTe Crystal Growth Furnace

    OpenAIRE

    Petr Praus; Eduard Belas; Jiri Bok; Roman Fesh; Jan Franc; Pavel Hoschl

    2006-01-01

    CdTe and (CdZn)Te bulk single crystals have been widely used as substrates for MBE and LPE epitaxy of infrared (HgCd)Te as well as gamma- and X-ray detectors. The Cd1-xZnxTe (x = 0.04-0.1) single crystals with diameter up to 100 mm and height at most 40 mm were prepared in our laboratory in a vertical arrangement by gradual cooling of the melt (the Vertical Gradient Freezing method). Achievement of excellent crystal quality required full control of Cd pressure during the growth process and ap...

  7. Optoelectronic devices based on graded bandgap structures utilising electroplated semiconductors

    OpenAIRE

    2016-01-01

    The main aim of the work presented in this thesis is to develop low-cost multi-junction graded bandgap solar cells using electroplated semiconductors. The semiconductor materials explored in this research are CdSe, ZnTe, CdS, CdMnTe and CdTe thin films. These layers were characterised for their structural, compositional, morphological, optical, and electrical features using XRD, Raman spectroscopy, EDX, SEM, UV-Vis spectroscopy, PEC cell, C-V, I-V and UPS measurement techniques respectively. ...

  8. Determination of a natural valence-band offset - The case of HgTe and CdTe

    Science.gov (United States)

    Shih, C. K.; Spicer, W. E.

    1987-01-01

    A method to determine a natural valence-band offset (NVBO), i.e., the change in the valence-band maximum energy which is intrinsic to the bulk band structures of semiconductors is proposed. The HgTe-CdTe system is used as an example in which it is found that the valence-band maximum of HgTe lies 0.35 + or - 0.06 eV above that of CdTe. The NVBO of 0.35 eV is in good agreement with the X-ray photoemission spectroscopy measurement of the heterojunction offset. The procedure to determine the NVBO between semiconductors, and its implication on the heterojunction band lineup and the electronic structures of semiconductor alloys, are discussed.

  9. High-resolution ionization detector and array of such detectors

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Douglas S. (Ypsilanti, MI); Rojeski, Ronald A. (Pleasanton, CA)

    2001-01-16

    A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

  10. Silicon Drift Detectors for ALICE

    CERN Document Server

    Navach, F; CERN. Geneva

    1992-01-01

    The Silicon Drift Detector (SDD) is a semiconductor, not yet extensively used in HEP experiment, which has an excellent spatial resolution and granularity about comparable to a pixel device requiring a number of readout channels two order of magnitude less.

  11. CdTe nanoparticles for the deposition of CdTe films using close spaced sublimation

    Science.gov (United States)

    Schumm, Benjamin; Althues, Holger; Kaskel, Stefan

    2010-08-01

    In this work a nanostructured CdTe powder was applied as a source material for CdTe film deposition via Close Spaced Sublimation (CSS). Growth kinetics and the resulting film properties were studied and compared to the films deposited from a commercially available CdTe bulk powder as source. The nanostructured powder was synthesized by a solvothermal elemental reaction of Cd and Te in ethylene diamine leading to particles of around 100-500 nm in diameter with a specific surface area of 4.1 m 2 g -1. An increase in the deposition rate by the factor of 1.7 was observed for the nanostructured powder as compared to the bulk material.

  12. Thin-film CdTe cells: Reducing the CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Plotnikov, V.; Liu, X.; Paudel, N.; Kwon, D.; Wieland, K.A.; Compaan, A.D., E-mail: alvin.compaan@utoledo.edu

    2011-08-31

    Polycrystalline thin-film CdTe is currently the dominant thin-film technology in world-wide PV manufacturing. With finite Te resources world-wide, it is appropriate to consider the limits to reducing the thickness of the CdTe layer in these devices. In our laboratory we have emphasized the use of magnetron sputtering for both CdS and CdTe achieving AM1.5 efficiency over 13% on 3 mm soda-lime glass with commercial TCO and 14% on 1 mm aluminosilicate glass. This deposition technique is well suited to good control of very thin layers and yields relatively small grain size which also facilitates high performance with ultra-thin layers. This paper describes our magnetron sputtering studies for fabrication of very thin CdTe cells. Our thinnest cells had CdTe thicknesses of 1 {mu}m, 0.5 {mu}m and 0.3 {mu}m and yielded efficiencies of 12%, 9.7% and 6.8% respectively. With thinner cells Voc, FF and Jsc are reduced. Current-voltage (J-V), temperature dependent J-V (J-V-T) and apparent quantum efficiency (AQE) measurements provide valuable information for understanding and optimizing cell performance. We find that the stability under light soak appears not to depend on CdTe thickness from 2.5 to 0.5 {mu}m. The use of semitransparent back contacts allows the study of bifacial response which is particularly useful in understanding carrier collection in the very thin devices.

  13. Schottky Barrier CdTe(Cl) Detectors for Planetary Missions

    Science.gov (United States)

    Eisen, Yosef; Floyd, Samuel

    2002-10-01

    Schottky barrier cadmium telluride (CdTe) radiation detectors of dimensions 2mm × 2mm × 1mm and segmented monolithic 3cm × 3 cm × 1mm are under study at GSFC for future NASA planetary instruments. These instruments will perform x-ray fluorescence spectrometry of the surface and monitor the solar x-ray flux spectrum, the excitation source for the characteristic x-rays emitted from the planetary body. The Near Earth Asteroid Rendezvous (NEAR) mission is the most recent example of such a remote sensing technique. Its x-ray fluorescence detectors were gas proportional counters with a back up Si PIN solar monitor. Analysis of NEAR data has shown the necessity to develop a solar x-ray detector with efficiency extending to 30keV. Proportional counters and Si diodes have low sensitivity above 9keV. Our 2mm × 2mm × 1mm CdTe operating at -30°C possesses an energy resolution of 250eV FWHM for 55Fe with unit efficiency to up to 30keV. This is an excellent candidate for a solar monitor. Another ramification of the NEAR data is a need to develop a large area detector system, 20-30 cm2, with cosmic ray charged particle rejection, for measuring the characteristic radiation. A 3cm × 3cm × 1mm Schottky CdTe segmented monolithic detector is under investigation for this purpose. A tiling of 2-3 such detectors will result in the desired area. The favorable characteristics of Schottky CdTe detectors, the system design complexities when using CdTe and its adaptation to future missions will be discussed.

  14. Development of a computer model for polycrystalline thin-film CuInSe{sub 2} and CdTe solar cells. Annual subcontract report, 1 January 1990--31 December 1990

    Energy Technology Data Exchange (ETDEWEB)

    Gray, J.L.; Schwartz, R.J.; Lee, Y.J. [Purdue Univ., Lafayette, IN (United States)

    1992-04-01

    This report describes work to develop a highly accurate numerical model for CuInSe{sub 2} and CdTe solar cells. ADEPT (A Device Emulation Program and Toolbox), a one-dimensional semiconductor device simulation code developed at Purdue University, was used as the basis of this model. An additional objective was to use ADEPT to analyze the performance of existing and proposed CuInSe{sub 2} and CdTe solar cell structures. The work is being performed in two phases. The first phase involved collecting device performance parameters, cell structure information, and material parameters. This information was used to construct the basic models to simulate CuInSe{sub 2} and CdTe solar cells. This report is a tabulation of information gathered during the first phase of this project on the performance of existing CuInSe{sub 2} and CdTe solar cells, the material properties of CuInSr{sub 2}, CdTe, and CdS, and the optical absorption properties of CuInSe{sub 2}, CdTe, and CdS. The second phase will entail further development and the release of a version of ADEPT tailored to CuInSe{sub 2} and CdTe solar cells that can be run on a personal computer. In addition, ADEPT will be used to analyze the performance of existing and proposed CuInSe{sub 2} and CdTe solar cell structures. 110 refs.

  15. Charge separation and transfer in hybrid type II tunneling structures of CdTe and CdSe nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Dieter Konrad Michael

    2013-11-08

    Closely packed nanocrystal systems have been investigated in this thesis with respect to charge separation by charge carrier tunneling. Clustered and layered samples have been analyzed using PL-measurements and SPV-methods. The most important findings are reviewed in the following. A short outlook is also provided for potential further aspects and application of the presented results. The main purpose of this thesis was to find and quantify electronic tunneling transfer in closely packed self-assembled nanocrystal structures presenting quantum mechanical barriers of about 1 nm width. We successfully used hybrid assemblies of CdTe and CdSe nanocrystals where the expected type II alignment between CdTe and CdSe typically leads to a concentration of electrons in CdSe and holes in CdTe nanocrystals. We were able to prove the charge selectivity of the CdTe-CdSe nanocrystal interface which induces charge separation. We mainly investigated the effects related to the electron transfer from CdTe to CdSe nanocrystals. Closely packing was achieved by two independent methods: the disordered colloidal clustering in solution and the layered assembly on dry glass substrates. Both methods lead to an inter-particle distance of about 1 nm of mainly organic material which acts as a tunneling barrier. PL-spectroscopy was applied. The PL-quenching of the CdTe nanocrystals in hybrid assemblies indicates charge separation by electron transfer from CdTe to CdSe nanocrystals. A maximum quenching rate of up to 1/100 ps was measured leading to a significant global PL-quenching of up to about 70 % for the CdTe nanocrystals. It was shown that charge separation dynamics compete with energy transfer dynamics and that charge separation typically dominates. The quantum confinement effect was used to tune the energetic offset between the CdTe and CdSe nanocrystals. We thus observe a correlation of PL-quenching and offset of the energy states for the electron transfer. The investigated PL

  16. Precipitação seletiva de tamanhos em nanopartículas semicondutoras coloidais de CdTe e CdSe: um estudo por espectroscopia UV-VIS

    Directory of Open Access Journals (Sweden)

    Lívia Cristina de Souza Viol

    2011-01-01

    Full Text Available The post-preparative size-selective precipitation technique was applied in CdTe and CdSe semiconductor nanocrystals prepared via colloidal route in water. The synthesis of CdTe and CdSe nanoparticles and the effect of the post-preparative size-selective precipitation have been characterized mainly by mean of ultraviolet and visible absorption spectroscopy (UV-Vis. It was demonstrated that the size-selective precipitation are able to isolate particles of different sizes and purify the nanoparticles as well.

  17. A germanium hybrid pixel detector with 55μm pixel size and 65,000 channels

    Science.gov (United States)

    Pennicard, D.; Struth, B.; Hirsemann, H.; Sarajlic, M.; Smoljanin, S.; Zuvic, M.; Lampert, M. O.; Fritzsch, T.; Rothermund, M.; Graafsma, H.

    2014-12-01

    Hybrid pixel semiconductor detectors provide high performance through a combination of direct detection, a relatively small pixel size, fast readout and sophisticated signal processing circuitry in each pixel. For X-ray detection above 20 keV, high-Z sensor layers rather than silicon are needed to achieve high quantum efficiency, but many high-Z materials such as GaAs and CdTe often suffer from poor material properties or nonuniformities. Germanium is available in large wafers of extremely high quality, making it an appealing option for high-performance hybrid pixel X-ray detectors, but suitable technologies for finely pixelating and bump-bonding germanium have not previously been available. A finely-pixelated germanium photodiode sensor with a 256 by 256 array of 55μm pixels has been produced. The sensor has an n-on-p structure, with 700μm thickness. Using a low-temperature indium bump process, this sensor has been bonded to the Medipix3RX photoncounting readout chip. Tests with the LAMBDA readout system have shown that the detector works successfully, with a high bond yield and higher image uniformity than comparable high-Z systems. During cooling, the system is functional around -80°C (with warmer temperatures resulting in excessive leakage current), with -100°C sufficient for good performance.

  18. Homogeneous CdTe quantum dots-carbon nanotubes heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, Kayo Oliveira [Grupo de Pesquisa em Química de Materiais – (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP 36301-160, São João del-Rei, MG (Brazil); Bettini, Jefferson [Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, CEP 13083-970, Campinas, SP (Brazil); Ferrari, Jefferson Luis [Grupo de Pesquisa em Química de Materiais – (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP 36301-160, São João del-Rei, MG (Brazil); Schiavon, Marco Antonio, E-mail: schiavon@ufsj.edu.br [Grupo de Pesquisa em Química de Materiais – (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP 36301-160, São João del-Rei, MG (Brazil)

    2015-01-15

    The development of homogeneous CdTe quantum dots-carbon nanotubes heterostructures based on electrostatic interactions has been investigated. We report a simple and reproducible non-covalent functionalization route that can be accomplished at room temperature, to prepare colloidal composites consisting of CdTe nanocrystals deposited onto multi-walled carbon nanotubes (MWCNTs) functionalized with a thin layer of polyelectrolytes by layer-by-layer technique. Specifically, physical adsorption of polyelectrolytes such as poly (4-styrene sulfonate) and poly (diallyldimethylammonium chloride) was used to deagglomerate and disperse MWCNTs, onto which we deposited CdTe quantum dots coated with mercaptopropionic acid (MPA), as surface ligand, via electrostatic interactions. Confirmation of the CdTe quantum dots/carbon nanotubes heterostructures was done by transmission and scanning electron microscopies (TEM and SEM), dynamic-light scattering (DLS) together with absorption, emission, Raman and infrared spectroscopies (UV–vis, PL, Raman and FT-IR). Almost complete quenching of the PL band of the CdTe quantum dots was observed after adsorption on the MWCNTs, presumably through efficient energy transfer process from photoexcited CdTe to MWCNTs. - Highlights: • Highly homogeneous CdTe-carbon nanotubes heterostructures were prepared. • Simple and reproducible non-covalent functionalization route. • CdTe nanocrystals homogeneously deposited onto multi-walled carbon nanotubes. • Efficient energy transfer process from photoexcited CdTe to MWCNTs.

  19. Lattice sites of Li in CdTe

    NARCIS (Netherlands)

    Restle, M; BharuthRam, K; Quintel, H; Ronning, C; Hofsass, H; Wahl, U; Jahn, SG

    1996-01-01

    The lattice site occupation of Li in CdTe at temperatures between 40 and 500 K was investigated with the emission channeling method. Radioactive Li-8 ions were implanted at low doses into CdTe single crystals. Emission channeling patterns of alpha-particles emitted in the nuclear decay of Li-8 (t(1/

  20. 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.

  1. Device Physics of Narrow Gap Semiconductors

    CERN Document Server

    Chu, Junhao

    2010-01-01

    Narrow gap semiconductors obey the general rules of semiconductor science, but often exhibit extreme features of these rules because of the same properties that produce their narrow gaps. Consequently these materials provide sensitive tests of theory, and the opportunity for the design of innovative devices. Narrow gap semiconductors are the most important materials for the preparation of advanced modern infrared systems. Device Physics of Narrow Gap Semiconductors offers descriptions of the materials science and device physics of these unique materials. Topics covered include impurities and defects, recombination mechanisms, surface and interface properties, and the properties of low dimensional systems for infrared applications. This book will help readers to understand not only the semiconductor physics and materials science, but also how they relate to advanced opto-electronic devices. The last chapter applies the understanding of device physics to photoconductive detectors, photovoltaic infrared detector...

  2. Analysis of Recombination in CdTe Heterostructures With Time-Resolved Two-Photon Excitation Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kuciauskas, Darius; Wernsing, Keith; Jensen, Soren Alkaersig; Barnes, Teresa M.; Myers, Thomas H.; Bartels, Randy A.

    2016-11-01

    We used time-resolved photoluminescence micro-scopy to analyze charge carrier transport and recombination in CdTe double heterostructures fabricated by molecular beam epitaxy (MBE). This allowed us to determine the charge carrier mobility in this system, which was found to be 500-625 cm2/(V s). Charge carrier lifetimes in the 15-100 ns range are limited by the interface recombination, and the data indicate higher interface recombination velocity near extended defects. This study describes a new method to analyze the spatial distribution of the interface recombination velocity and the interface defects in semiconductor heterostructures.

  3. Structural, Optical, and Magnetic Properties of Co Doped CdTe Alloy Powders Prepared by Solid-State Reaction Method

    Directory of Open Access Journals (Sweden)

    M. Rigana Begam

    2013-01-01

    Full Text Available Co doped CdTe powder samples were prepared by solid-state reaction method. In the present work effect of Co doping on structural, optical, and magnetic properties has been studied. X-ray diffraction studies confirm zinc blend structure for all the samples. The lattice parameter showed linear increase with the increase in Co content. The elemental constituents were characterized by EDAX. Optical studies showed the increase in band gap with increase in Co level. The samples were diluted magnetic semiconductors and exhibited clear hysteresis loop showing room temperature ferromagnetism as confirmed by vibrating sample magnetometer.

  4. An improved hand-held four-detector gamma-probe for radioassisted oncological surgery

    CERN Document Server

    Dusi, W; Bollini, D; Moroni, C; Ricard, M

    2000-01-01

    The performance of an improved intraoperative gamma-probe for radioassisted oncological surgery is presented and discussed. The probe is based on a square array of four 5x5 mm sup 2 coplanar CdTe room temperature semiconductor detectors and each detector has an independent read out electronic chain, allowing an original handling of the signal. Therefore, the search for gamma-emission hot points may be carried out in two different, independent ways: (1) Finding out the position of the probe corresponding to the maximum value of the total counting rate, on the basis of a trial and error procedure (typical for the conventional probe; (2) Finding out the position of the probe where both the differences between the counting rate performed by orthogonal, adjacent halves of the array vanish (differential method). This makes the new probe sensitive to the bidimensional gradient of the gamma-ray flux, measured on the scanned plane. Furthermore, the algebraic sign of the difference indicates in which direction the prob...

  5. Effects of substrate voltage on noise characteristics and hole lifetime in SOI metal-oxide-semiconductor field-effect transistor photon detector.

    Science.gov (United States)

    Putranto, Dedy Septono Catur; Priambodo, Purnomo Sidi; Hartanto, Djoko; Du, Wei; Satoh, Hiroaki; Ono, Atsushi; Inokawa, Hiroshi

    2014-09-08

    Low-frequency noise and hole lifetime in silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) are analyzed, considering their use in photon detection based on single-hole counting. The noise becomes minimum at around the transition point between front- and back-channel operations when the substrate voltage is varied, and increases largely on both negative and positive sides of the substrate voltage showing peculiar Lorentzian (generation-recombination) noise spectra. Hole lifetime is evaluated by the analysis of drain current histogram at different substrate voltages. It is found that the peaks in the histogram corresponding to the larger number of stored holes become higher as the substrate bias becomes larger. This can be attributed to the prolonged lifetime caused by the higher electric field inside the body of SOI MOSFET. It can be concluded that, once the inversion channel is induced for detection of the photo-generated holes, the small absolute substrate bias is favorable for short lifetime and low noise, leading to high-speed operation.

  6. Semiconductor heterojunctions

    CERN Document Server

    Sharma, B L

    1974-01-01

    Semiconductor Heterojunctions investigates various aspects of semiconductor heterojunctions. Topics covered include the theory of heterojunctions and their energy band profiles, electrical and optoelectronic properties, and methods of preparation. A number of heterojunction devices are also considered, from photovoltaic converters to photodiodes, transistors, and injection lasers.Comprised of eight chapters, this volume begins with an overview of the theory of heterojunctions and a discussion on abrupt isotype and anisotype heterojunctions, along with graded heterojunctions. The reader is then

  7. Synthesis, purification, and characterization of perovskite semiconductor CsPbBr3 as a new candidate for y-ray detector(Conference Presentation)

    Science.gov (United States)

    Chung, Duck Young; Kanatzidis, Mercouri G.; Meng, Fang; Malliakas, Christos D.

    2016-09-01

    CsPbBr3 has direct band gap (orange color, 2.25 eV), high density (4.85 g/cm3), attenuation coefficient comparable to CZT, and high resistivity 10^9 ohm•cm. These fundamental physical properties of CsPbBr3well meet the requirements for gamma-ray detector materials. CsPbBr3 exhibits the carrier mobility-lifetime product in the order of 10^-4 cm2/V promising enough to be further developed for practical applications. The major challenge in the process to further enhance the detection performance is the carrier traps present at a deep level of the energy gap which should be minimized. We report the synthesis, purification, crystal growth and physical characterization of the CsPbBr3 crystals obtained by new processes we developed for highly pure materials with reduced carrier traps. The starting binary materials were prepared by reaction of Cs2CO3/HBr and Pb(ac)2/HBr in aqueous solution. Purification of materials was performed by sublimation, bromination with HBr gas, and filtration of molten materials. Large single crystals were grown by the vertical Bridgman and EelectroDynamic Gradient method and cut to the dimensions appropriate for assessment of the material for gamma-ray detector applications. All characterization including optical characteristics, charge transport properties, photoconductivity, and gamma-ray spectroscopy from the new single crystals of CsPbBr3 will be presented. In addition, the charge carrier traps profile has been studied for this compound by Deep-Level Transient Spectroscopy (DLTS), Thermally Stimulated Luminescence (TSL), and Photoluminescence (PL) and will be presented.

  8. Extracellular biosynthesis of CdTe quantum dots by the fungus Fusarium oxysporum and their anti-bacterial activity

    Science.gov (United States)

    Syed, Asad; Ahmad, Absar

    2013-04-01

    The growing demand for semiconductor [quantum dots (Q-dots)] nanoparticles has fuelled significant research in developing strategies for their synthesis and characterization. They are extensively investigated by the chemical route; on the other hand, use of microbial sources for biosynthesis witnessed the highly stable, water dispersible nanoparticles formation. Here we report, for the first time, an efficient fungal-mediated synthesis of highly fluorescent CdTe quantum dots at ambient conditions by the fungus Fusarium oxysporum when reacted with a mixture of CdCl2 and TeCl4. Characterization of these biosynthesized nanoparticles was carried out by different techniques such as Ultraviolet-visible (UV-Vis) spectroscopy, Photoluminescence (PL), X-ray Diffraction (XRD), X-ray Photoelectron spectroscopy (XPS), Transmission Electron Microscopy (TEM) and Fourier Transformed Infrared Spectroscopy (FTIR) analysis. CdTe nanoparticles shows antibacterial activity against Gram positive and Gram negative bacteria. The fungal based fabrication provides an economical, green chemistry approach for production of highly fluorescent CdTe quantum dots.

  9. Identification of Ag-acceptors in $^{111}Ag^{111}Cd$ doped ZnTe and CdTe

    CERN Document Server

    Hamann, J; Deicher, M; Filz, T; Lany, S; Ostheimer, V; Strasser, F; Wolf, H; Wichert, T

    2000-01-01

    Nominally undoped ZnTe and CdTe crystals were implanted with radioactive /sup 111/Ag, which decays to /sup 111/Cd, and investigated by photoluminescence spectroscopy (PL). In ZnTe, the PL lines caused by an acceptor level at 121 meV are observed: the principal bound exciton (PBE) line, the donor-acceptor pair (DAP) band, and the two-hole transition lines. In CdTe, the PBE line and the DAP band that correspond to an acceptor level at 108 meV appear. Since the intensities of all these PL lines decrease in good agreement with the half-life of /sup 111/Ag of 178.8 h, both acceptor levels are concluded to be associated with defects containing a single Ag atom. Therefore, the earlier assignments to substitutional Ag on Zn- and Cd-lattice sites in the respective II-VI semiconductors are confirmed. The assignments in the literature of the S/sub 1/, S /sub 2/, and S/sub 3/ lines in ZnTe and the X/sub 1//sup Ag/, X/sub 2 //sup Ag//C/sub 1//sup Ag/, and C/sub 2//sup Ag/ lines in CdTe to Ag- related defect complexes are ...

  10. Acceptors in II-IV Semiconductors - Incorporation and Complex Formation

    CERN Multimedia

    2002-01-01

    A strong effort is currently devoted to the investigation of defects and the electrical activation of dopant atoms in II-VI semiconductors. In particular, the knowledge about the behaviour of acceptors, prerequisite for the fabrication of p-type semiconductors, is rather limited. The perturbed $\\,{\\gamma\\gamma}$ -angular correlation technique (PAC) and the photoluminescence spectroscopy (PL) using the radioactive isotopes $^{77}\\!$Br and $^{111}\\!$Ag will be applied for investigating the behaviour of acceptor dopant atoms and their interactions with defects in II-VI semiconductors. The main topic will be the identification of the technical conditions for the incorporation of electrically active acceptors in the II-VI semiconductors ~ZnS, ZnSe, ZnTe, CdS, CdSe, and CdTe with particular emphasis on the compounds~ CdTe, ZnSe, and ZnTe. The investigations will be supplemented by first exploratory PL experiments with the group V acceptors $^{71}\\!$As and $^{121}\\!$Sb. With help of the probe $^{111}\\!$Ag, the pos...

  11. NUMERICAL SIMULATION AND OPTIMIZATION OF PERFORMANCES OF A SOLAR CELL BASED ON CdTe

    Directory of Open Access Journals (Sweden)

    A. M. Ferouani

    2015-07-01

    Full Text Available This article has as an aim the study and the simulation of the photovoltaic cells containing CdTe materials, contributing to the development of renewable energies, and able to feed from the houses, the shelters as well as photovoltaic stations… etc. CdTe is a semiconductor having a structure of bands with an indirect gap of a value of 1,5 eV at ambient temperature what means that photon wavelength of approximately 1200 nm will be able to generate an electron-hole pair. One speaks about photogeneration. We will lay the stress, initially, on the essential design features of a photovoltaic module (the open-circuit tension, the short-circuit current, the fill factor, and the output of the cell, our results was simulated with the SCAPS computer code in one dimension which uses electrical characteristics DC and AC of the thin layers heterojunctions. The results obtained after optimization are: VCO = 0.632V, Jsc = 39.1 mA/cm2, FF=82.98 % and the output energy of conversion is 18.26%.Optimization is made according to the temperature and the wavelength.

  12. Advances in all-sputtered CdTe solar cells on flexible substrates

    Science.gov (United States)

    Wieland, Kristopher; Mahabaduge, Hasitha; Vasko, Anthony; Compaan, Alvin

    2010-03-01

    The University of Toledo II-VI semiconductor group has developed magnetron sputtering (MS) for the deposition of thin films of CdS, CdTe, and related materials for photovoltaic applications. On glass superstrates, we have reached air mass 1.5 efficiencies of 14%.[1] Recently we have studied the use of MS for the fabrication of thin-film CdS/CdTe cells on flexible polyimide superstrates. This takes advantage of the high film quality that can be achieved at substrate temperatures below 300 C when RF MS is used. Our recent CdS/CdTe solar cells have reached 10.5% on flexible polyimide substrates. [2] This all-sputtered cell (except for back contact) has a structure of polyimide/ZnO:Al/ZnO/CdS/CdTe/Cu/Au. The physics of this device will be discussed through the use of spectral quantum efficiency and current-voltage measurements as a function of CdTe layer thickness. Pathways toward further increases in device efficiencies will also be discussed. [1] Appl. Phys. Lett. 85, 684 (2004) [2] Phys. Stat. Sol. (B) 241, No. 3, 779--782 (2004)

  13. Radiation detectors laboratory; Laboratorio de detectores de radiacion

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez J, F.J. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    The Radiation detectors laboratory was established with the assistance of the International Atomic Energy Agency which gave this the responsibility to provide its services at National and regional level for Latin America and it is located at the ININ. The more expensive and delicate radiation detectors are those made of semiconductor, so it has been put emphasis in the use and repairing of these detectors type. The supplied services by this laboratory are: selection consultant, detectors installation and handling and associated systems. Installation training, preventive and corrective maintenance of detectors and detection systems calibration. (Author)

  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. A Comprehensive Study on Mo/CdTe Metal-Semiconductor Interface Deposited by Radio Frequency Magnetron Sputtering.

    Science.gov (United States)

    Dhar, N; Khan, N A; Chelvanathan, P; Akhtaruzzaman, M; Alam, M M; Alothman, Z A; Sopian, K; Amin, N

    2015-11-01

    Metal-semiconductor (MS) junction between Mo and CdTe, which is one of the fundamental issues for CdTe based solar cell, has been investigated for films deposited on different substrates. XRD pattern of Mo/CdTe films on the polyimide (PI) substrate shows a strong preferential orientation of MoTe2 in (100) at 2θ = 29.44 degrees, which becomes less apparent as deposition time of CdTe increases. However, on soda lime glass (SLG) no such XRD reflection pattern is observed. Moreover, from EDX measurement, Mo-Te compound also identifies MoTe2 at Mo/CdTe interface on PI substrate, which is not present on SLG. Bulk carrier concentration of Mo/CdTe films on PI substrate for lower deposition time of CdTe is found 1.42 x 10(18) cm(-3), which is almost equal to MoTe2. Thereafter, it decreases as CdTe growth time increases. The type of unintentionally formed MoTe2 on PI substrate is found to be n-type in nature. Lattice constants of a = 6.5 Å for CdTe and a = 3.52 Å for MoTe2 are found from nanostructure study by TEM.

  16. CdTe and CdSe Quantum Dots Cytotoxicity: A Comparative Study on Microorganisms

    Science.gov (United States)

    Gomes, Suzete A.O.; Vieira, Cecilia Stahl; Almeida, Diogo B.; Santos-Mallet, Jacenir R.; Menna-Barreto, Rubem F. S.; Cesar, Carlos L.; Feder, Denise

    2011-01-01

    Quantum dots (QDs) are colloidal semiconductor nanocrystals of a few nanometers in diameter, being their size and shape controlled during the synthesis. They are synthesized from atoms of group II–VI or III–V of the periodic table, such as cadmium telluride (CdTe) or cadmium selenium (CdSe) forming nanoparticles with fluorescent characteristics superior to current fluorophores. The excellent optical characteristics of quantum dots make them applied widely in the field of life sciences. Cellular uptake of QDs, location and translocation as well as any biological consequence, such as cytotoxicity, stimulated a lot of scientific research in this area. Several studies pointed to the cytotoxic effect against micoorganisms. In this mini-review, we overviewed the synthesis and optical properties of QDs, and its advantages and bioapplications in the studies about microorganisms such as protozoa, bacteria, fungi and virus. PMID:22247686

  17. Synthesis of CdTe colloidal quantum dots (QDs) in water

    Institute of Scientific and Technical Information of China (English)

    Rong HE; Xiaogang YOU; Hongye TIAN; Feng GAO; Daxiang CUI

    2008-01-01

    The comparison of growth processes and fluorescent properties of CdTe semiconductor quantum dots (QDs) that are synthesized in water with different modifiers are discussed in this paper. The samples are characterized through ultraviolet,visible spectra (UV,Vis),photoluminescence spectra (PL) and zeta potential. The results show that when the reaction time is prolonged for the same modifier, the ultraviolet absorption peak and fluorescent emission peak present obvious red shifts and the diameters of the QDs continuously increase. With the same reaction time but different modifiers, QDs with different diameters can be gained. The average full width at half maximum of the photoluminescence spectra is about 50 nm which shows that the monodispersity is quite good.Under the best reaction conditions, the highest quantum yield (QY) can be attained by using thioglycollic acid (TGA) as modifier when the reaction time is 240 min.The zeta potential is influenced by the modifier and pH.

  18. CdTe and CdSe Quantum Dots Cytotoxicity: A Comparative Study on Microorganisms

    Directory of Open Access Journals (Sweden)

    Denise Feder

    2011-12-01

    Full Text Available Quantum dots (QDs are colloidal semiconductor nanocrystals of a few nanometers in diameter, being their size and shape controlled during the synthesis. They are synthesized from atoms of group II–VI or III–V of the periodic table, such as cadmium telluride (CdTe or cadmium selenium (CdSe forming nanoparticles with fluorescent characteristics superior to current fluorophores. The excellent optical characteristics of quantum dots make them applied widely in the field of life sciences. Cellular uptake of QDs, location and translocation as well as any biological consequence, such as cytotoxicity, stimulated a lot of scientific research in this area. Several studies pointed to the cytotoxic effect against micoorganisms. In this mini-review, we overviewed the synthesis and optical properties of QDs, and its advantages and bioapplications in the studies about microorganisms such as protozoa, bacteria, fungi and virus.

  19. Auger relative sensitivivity factors for CdTe oxide

    OpenAIRE

    P. Bartolo-Pérez; J. L. Peña; M.H. Farías

    1999-01-01

    The Auger lineshape of Te MNN in measurements of Auger spectra of CdTe oxide films with various degrees of oxidation was analyzed. By using standards from stoichiometric compounds, Auger relative sensitivity factors (RSF´s) of Cd, Te and O for CdTe oxide thin films were obtained. The value of the RFS of oxygen is about constant, 0.27-0.28, for the standard compound, CdO, TeO2 and CdTeO3 (considering the RSF of Cd as 1). However, the obtained RSF of Te changes from 0.69 in CdTe up to 0.87 in C...

  20. Process Development for High Voc CdTe Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Ferekides, C. S.; Morel, D. L.

    2011-05-01

    This is a cumulative and final report for Phases I, II and III of this NREL funded project (subcontract # XXL-5-44205-10). The main research activities of this project focused on the open-circuit voltage of the CdTe thin film solar cells. Although, thin film CdTe continues to be one of the leading materials for large-scale cost-effective production of photovoltaics, the efficiency of the CdTe solar cells have been stagnant for the last few years. This report describes and summarizes the results for this 3-year research project.

  1. Visible response of λc=2.5´m HgCdTe HDVIP detectors

    Science.gov (United States)

    Stapelbroek, Maryn G.; Guptill, Matthew; D'Souza, Arvind I.; Bryan, Elizabeth R.; Beck, J. D.; Kinch, M. A.; Robinson, James E.

    2004-08-01

    Cu-doped HDVIP detectors with different cut-off wavelengths are routinely manufactured. The DRS HDVIP detector technology is a front-side-illuminated detector technology. There is no substrate to absorb the visible photons as in backside-illuminated detectors and these detectors should be well suited to respond to visible light. However, HDVIP detectors are passivated using CdTe that absorbs the visible light photons. CdTe strongly absorbs photons of wavelength shorter than about 800 nm. Detectors with varying thickness of CdTe passivation layers were fabricated to investigate the visible response of the 2.5-μm-cutoff detectors. A model was developed to predict the quantum efficiency of the detectors in the near infrared and visible wavelength regions as a function of CdTe thickness. Individual photodiodes (λc = 2.5 μm) in test bars were examined. Measurements of the quantum efficiency as a function of wavelength region will be presented and compared to the model predictions.

  2. 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

  3. 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

  4. Ion chamber based neutron detectors

    Science.gov (United States)

    Derzon, Mark S; Galambos, Paul C; Renzi, Ronald F

    2014-12-16

    A neutron detector with monolithically integrated readout circuitry, including: a bonded semiconductor die; an ion chamber formed in the bonded semiconductor die; a first electrode and a second electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; and the readout circuitry which is electrically coupled to the first and second electrodes. The bonded semiconductor die includes an etched semiconductor substrate bonded to an active semiconductor substrate. The readout circuitry is formed in a portion of the active semiconductor substrate. The ion chamber has a substantially planar first surface on which the first electrode is formed and a substantially planar second surface, parallel to the first surface, on which the second electrode is formed. The distance between the first electrode and the second electrode may be equal to or less than the 50% attenuation length for neutrons in the neutron absorbing material filling the ion chamber.

  5. Device Fabrication using Crystalline CdTe and CdTe Ternary Alloys Grown by MBE

    Energy Technology Data Exchange (ETDEWEB)

    Zaunbrecher, Katherine; Burst, James; Seyedmohammadi, Shahram; Malik, Roger; Li, Jian V.; Gessert, Timothy A.; Barnes, Teresa

    2015-06-14

    We fabricated epitaxial CdTe:In/CdTe:As homojunction and CdZnTe/CdTe and CdMgTe/CdTe heterojunction devices grown on bulk CdTe substrates in order to study the fundamental device physics of CdTe solar cells. Selection of emitter-layer alloys was based on passivation studies using double heterostructures as well as band alignment. Initial results show significant device integration challenges, including low dopant activation, high resistivity substrates and the development of low-resistance contacts. To date, the highest open-circuit voltage is 715 mV in a CdZnTe/CdTe heterojunction following anneal, while the highest fill factor of 52% was attained in an annealed CdTe homojunction. In general, all currentvoltage measurements show high series resistance, capacitancevoltages measurements show variable doping, and quantum efficiency measurements show low collection. Ongoing work includes overcoming the high resistance in these devices and addressing other possible device limitations such as non-optimum junction depth, interface recombination, and reduced bulk lifetime due to structural defects.

  6. Growth of CdTe: Al films; Crecimiento de peliculas de CdTe: Al

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez A, M.; Zapata T, M. [CICATA-IPN, 89600 Altamira, Tamaulipas (Mexico); Melendez L, M. [CINVESTAV-IPN, A.P. 14-740, 07000 Mexico D.F. (Mexico); Pena, J.L. [CINVESTAV-IPN, A.P. 73 Cordemex, 97310 Merida, Yucatan (Mexico)

    2006-07-01

    CdTe: AI films were grown by the close space vapor transport technique combined with free evaporation (CSVT-FE). The Aluminum (Al) evaporation was made by two kinds of sources: one made of graphite and the other of tantalum. The films were deposited on glass substrates. The Al source temperature was varied maintaining the CdTe source temperature fixed as well as the substrate temperature. The films were characterized by x-ray energy dispersive analysis (EDAX), x-ray diffraction and optical transmission. The results showed for the films grown with the graphite source for Al evaporation, the Al did not incorporate in the CdTe matrix, at least to the level of EDAX sensitivity; they maintained the same crystal structure and band gap. For the samples grown with the tantalum source, we were able to incorporate the Al. The x-ray diffraction patterns show that the films have a crystal structure that depends on Al concentration. They were cubic up to 2.16 at. % Al concentration; for 19.65 at. % we found a mixed phase; for Al concentration higher than 21 at. % the films were amorphous. For samples with cubic structure it was found that the lattice parameter decreases and the band gap increases with Al concentration. (Author)

  7. Controlled Synthesis of Nanoscale CdTe Urchins

    Institute of Scientific and Technical Information of China (English)

    BAO Jian; SHEN Yue; SUN Yan; YUE Yang; CHEN Xin; DAI Ning

    2009-01-01

    We presented a simple route to prepare nanoscale CdTe urchins in a tri-n-octylphosphine oxide(TOPO)system.CdTe urchins consisted of a core and several attached arms.The arms were ca.3 nm wide,and their lengths could be controlled with the reaction time.The authors investigated the optical absorption and structural properties of the prepared CdTe.The lengths of the arms could be tuned into CdTe nanourchins,which led to a change in the photophysical properties of the nanoscale CdTe urchins.The results,including transmission electron microscopy(TEM) and absorption spectra,indicated that mesoporous silica and aminopropyltriethoxysilane(APTES) contributed to the formation of nanoscale CdTe urchins.

  8. Modeling Copper Diffusion in Polycrystalline CdTe Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Akis, Richard [Arizona State University; Brinkman, Daniel [Arizona State University; Sankin, Igor [First Solar; Fang, Tian [First Solar; Guo, Da [Arizona State Univeristy; Vasileska, Dragica [Arizona State University; Ringhofer, Christain [Arizona State University

    2014-06-06

    It is well known that Cu plays an important role in CdTe solar cell performance as a dopant. In this work, a finite-difference method is developed and used to simulate Cu diffusion in CdTe solar cells. In the simulations, which are done on a two-dimensional (2D) domain, the CdTe is assumed to be polycrystalline, with the individual grains separated by grain boundaries. When used to fit experimental Cu concentration data, bulk and grain boundary diffusion coefficients and activation energies for CdTe can be extracted. In the past, diffusion coefficients have been typically obtained by fitting data to simple functional forms of limited validity. By doing full simulations, the simplifying assumptions used in those analytical models are avoided and diffusion parameters can thus be determined more accurately

  9. Extracting Cu Diffusion Parameters in Polycrystalline CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Akis, Richard [Arizona State Univeristy; Brinkman, Daniel [Arizona State Univeristy; Sankin, Igor [First Solar; Fang, Tian [First Solar; Guo, Da [Arizona State Univeristy; Dragica, Vasileska [Arizona State Univeristy; Ringhofer, Christian [Arizona State University

    2014-06-13

    It is well known that Cu plays an important role in CdTe solar cell performance as a dopant. In this work, a finite-difference method is developed and used to simulate Cu diffusion in CdTe solar cells. In the simulations, which are done on a two-dimensional (2D) domain, the CdTe is assumed to be polycrystal-line, with the individual grains separated by grain boundaries. When used to fit experimental Cu concentration data, bulk and grain boundary diffusion coefficients and activation energies for CdTe can be extracted. In the past, diffusion coefficients have been typically obtained by fitting data to simple functional forms of limited validity. By doing full simulations, the simplifying assumptions used in those analytical models are avoided and diffusion parameters can thus be determined more accurately.

  10. Studies of key technologies for CdTe solar modules

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, CdS thin films, which act as the window layer and n-type partner to the p-type CdTe layer, were prepared by chemical bath deposition (CBD). CdTe thin films were deposited by the close-spaced sublimation (CSS) method. To obtain high-quality back contacts, a Te-rich layer was created with chemical etching and back contact materials were applied after CdTe annealing. The results indicate that the ZnTe/ZnTe:Cu complex layers show superior performance over other back contacts. Finally, by using laser scribing and mechanical scribing, the CdTe mini-modules were fabricated, in which a glass/SnO2:F/CdS/CdTe/ZnTe/ZnTe:Cu/Ni solar module with a PWQC-confirmed total-area efficiency of 7.03% (54 cm2) was achieved.

  11. Spatial Distribution of Dopant Incorporation in CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Guthrey, Harvey; Moseley, John; Colegrove, Eric; Burst, James; Albin, David; Metzger, Wyatt; Al-Jassim, Mowafak

    2016-11-21

    In this work we use state-of-the-art cathodoluminescence (CL) spectrum imaging that provides spectrum-per-pixel mapping of the CL emission to examine how dopant elements are incorporated into CdTe. Emission spectra and intensity are used to monitor the spatial distribution of additional charge carriers through characteristic variations in the CL emission based on theoretical modeling. Our results show that grain boundaries play a role in the incorporation of dopants in CdTe, whether intrinsic or extrinsic. This type of analysis is crucial for providing feedback to design different processing schedules that optimize dopant incorporation in CdTe photovoltaic material, which has struggled to reach high carrier concentration values. Here, we present results on CdTe films exposed to copper, phosphorus, and intrinsic doping treatments.

  12. Visible to SWIR response of HgCdTe HDVIP detectors

    Science.gov (United States)

    D'Souza, A. I.; Robinson, E. W.; Stapelbroek, M. G.; Wong, W.; Skokan, M.; Shih, H.-D.

    2009-05-01

    Detectors that have broadband response from the visible (~ 400 nm) to near infrared (~ 2.5 μm) have remote sensing hyperspectral applications on a single chip. 2.2 and 2.5 μm cutoff detectors permit operation in the 200 K range. The DRS HDVIP detector technology is a front side illuminated detector technology. Consequently, there is no substrate to absorb the visible photons as in backside-illuminated detectors and these 2.2 and 2.5-μm-cutoff detectors should be well suited to respond to visible light. However, HDVIP detectors are passivated using CdTe that absorbs the visible light photons. CdTe with a direct bandgap ~ 1.6 eV strongly absorbs photons of wavelength shorter than about 800 nm. Detectors in 320 x 6 arrays with varying thickness of CdTe passivation layers were fabricated to investigate the visible response of the 2.5-μm-cutoff detectors. The SWIR HDVIP detectors have well known high quantum efficiency (QE) in the near infrared region. Focus here was in acquiring array level data in the visible region of the spectrum. 320 x 6 FPA QE and NEI data was acquired using a 642 nm narrow band filter with 50 % points at 612 nm and 698 nm. The array QE average is ~ 70 % for the array with CdTe passivation thickness = 44.5 nm. The NEI is ~ 5 x 1010 ph/cm2/s at a flux Φ = 5.36 x 1013 ph/cm2/s. QE for an array with CdTe passivation thickness = 44.5 nm is ~ 10 % higher than an array with CdTe passivation thickness = 79.3 nm. In addition, a model that takes into account the complex optical properties of every layer in the HDVIP photodiode architecture was developed to predict the QE of the detectors in the near infrared and visible wavelength regions as a function of CdTe thickness. Measured QE as a function of wavelength is not a good match to the model QE probably due to limitations in the measured QE and knowledge of optical constants that are input into the model.

  13. CdTe Photovoltaic Devices for Solar Cell Applications

    Science.gov (United States)

    2011-12-01

    July 28, 2011 14. ABSTRACT Cadmium telluride ( CdTe ) has been recognized as a promising photovoltaic material for thin - film solar cells because of...mail.mil Phone: 301 394 0963 ABSTRACT Cadmium telluride ( CdTe ) has been recognized as a promising photovoltaic material for thin - film ...absorption coefficient allows films as thin as 2 μm to absorb more than 98% of the above-bandgap radiation. Cells with efficiencies near 17% have been

  14. CdTe Photovoltaics for Sustainable Electricity Generation

    Science.gov (United States)

    Munshi, Amit; Sampath, Walajabad

    2016-09-01

    Thin film CdTe (cadmium telluride) is an important technology in the development of sustainable and affordable electricity generation. More than 10 GW of installations have been carried out using this technology around the globe. It has been demonstrated as a sustainable, green, renewable, affordable and abundant source of electricity. An advanced sublimation tool has been developed that allows highly controlled deposition of CdTe films onto commercial soda lime glass substrates. All deposition and treatment steps can be performed without breaking the vacuum within a single chamber in an inline process that can be conveniently scaled to a commercial process. In addition, an advanced cosublimation source has been developed to allow the deposition of ternary alloys such as Cd x Mg1- x Te to form an electron reflector layer which is expected to address the voltage deficits in current CdTe devices and to achieve very high efficiency. Extensive materials characterization, including but not limited to scanning electron microscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, high resolution transmission electron microscopy and electron back-scatter diffraction, has been performed to get a better understanding of the effects of processing conditions on CdTe thin film photovoltaics. This combined with computer modeling such as density function theory modeling gives a new insight into the mechanism of CdTe photovoltaic function. With all these efforts, CdTe photovoltaics has seen great progress in the last few years. Currently, it has been recorded as the cheapest source of electricity in the USA on a commercial scale, and further improvements are predicted to further reduce the cost while increasing its utilization. Here, we give an overview of the advantages of thin film CdTe photovoltaics as well as a brief review of the challenges that need to be addressed. Some fundamental studies of processing conditions for thin film CdTe are also presented

  15. Dynamic effects in CdTe quantum-dot LEDs

    OpenAIRE

    Gallardo, D. E.

    2006-01-01

    In this work the electrical and electroluminescence properties CdTe nanocrystal films were analysed. The structure consisted of a multilayer of CdTe nanocrystals deposited by the layer-by-layer technique, sandwiched between an ITO anode and an aluminium cathode. The first part of this work was dedicated to structural and process improvement. Earlier devices, produced through a layer-by-layer (LbL) manual procedure, had an average thickness of 30nm per nanocrystal monolayer,...

  16. Organic Semiconductors and its Applications

    Science.gov (United States)

    Kamalasanan, M. N.

    2011-10-01

    Organic semiconductors in the form of evaporated or spin coated thin films have many optoelectronic applications in the present electronic industry. They are frequently used in many type of displays, photo detectors, photoconductors for photocopiers and photovoltaic cells. But many p-conjugated molecules and polymer based devices do not provide satisfactory device performance and operational stability. Most of these problems are related to the interfaces they make with other organic materials and electrodes and the low conductivity of the organic layers. The study of organic-metal and organic—organic interfaces as well as electrical doping of organic semiconductors are very important areas of research at present. In this talk, I will be discussing some of the recent advances in this field as well as some of our own results in the area of interface modification and electrical doping of organic semiconductors.

  17. Use of semiconductor detector c-Si microstrip type in obtaining the digital radiographic imaging of phantoms and biological samples of mammary glands; Empleo de detector semiconductor de c-Si del tipo microbandas en la obtencion de imagenes radiograficas digitales de maniquies y muestras biologicas de mamas

    Energy Technology Data Exchange (ETDEWEB)

    Leyva, A.; Cabal, A.; Pinera, I.; Abreu, Y.; Cruz, C. M. [Centro de Estudios Avanzados y Desarrollo Nuclear, C. Habana, Cuba (Cuba); Montano, L. M.; Diaz, C. C.; Fontaine, M. [IPN, Centro de Investigaciones y Estudios Avanzados, Mexico D. F. (Mexico); Ortiz, C. M. [ISSSTE, Hospital General Tacuba, Clinica de Mama y Gineco-oncologia, Mexico D. F. (Mexico); Padilla, F. [Instituto Superior de Tecnologias y Ciencias Aplicadas, C. Habana, Cuba (Cuba); De la Mora, R. [Centro de Control Estatal de Equipos Medicos, C. Habana, Cuba (Cuba)], e-mail: aleyva@ceaden.edu.cu

    2009-07-01

    The present work synthesizes the experimental results obtained in the characterization of 64 micro strips crystalline silicon detector designed for experiments in high energies physics, with the objective of studying its possible application in advanced medical radiography, specifically in digital mammography and angiography. The research includes the acquisition of two-dimensional radiography of a mammography phantom using the scanning method, and its comparison with similar images simulated mathematically for different X rays sources. The paper also shows the experimental radiography of two biological samples taken from biopsies of mammas, where it is possible to identify the presence of possible pathological lesions. The results reached in this work point positively toward the effective possibility of satisfactorily introducing those advanced detectors in medical digital imaging applications. (Author)

  18. A study into the role of surface capping on energy transfer in metal cluster-semiconductor nanocomposites

    Science.gov (United States)

    Bain, Dipankar; Paramanik, Bipattaran; Sadhu, Suparna; Patra, Amitava

    2015-12-01

    Metal cluster-semiconductor nanocomposite materials remain a frontier area of research for the development of optoelectronic, photovoltaic and light harvesting devices because metal nanoclusters and semiconductor QDs are promising candidates for photon harvesting. Here, we have designed well defined metal cluster-semiconductor nanostructures using different surface capped negatively charged Au25 nanoclusters (Au NCs) and positively charged cysteamine capped CdTe quantum dots using electrostatic interactions. The main focus of this article is to address the impact of surface capping agents on the photophysical properties of Au cluster-CdTe QD hybrid nanocomposites. Steady state and time resolved spectroscopic studies reveal that photoluminescence quenching, radiative and nonradiative rate, and energy transfer between Au nanoclusters and CdTe QDs have been influenced by the nature of the capping agent. We have calculated the energy transfer related parameters such as the overlap integral, distance between donor and acceptor, Förster distance, efficiency of energy transfer and rate of energy transfer from CdTe QDs to three different Au NCs. Photoluminescence quenching varies from 73% to 43% when changing the capping agents from bovine serum albumin (BSA) to glutathione (GSH). The efficiency of the energy transfer from CdTe QDs to BSA-capped Au NCs is found to be 83%, for Cys-capped Au NCs it was 46% and for GSH-capped Au NCs it was 35%. The efficiency depends on the number of Au clusters attached per QD. This reveals that the nature of capping ligands plays a crucial role in the energy transfer phenomena from CdTe QDs to Au NCs. Interesting findings reveal that the efficient energy transfer in metal cluster-semiconductor nanocomposites may open up new possibilities in designing artificial light harvesting systems for future applications.Metal cluster-semiconductor nanocomposite materials remain a frontier area of research for the development of optoelectronic

  19. High-quality CdTe films from nanoparticle precursors

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, D.L.; Pehnt, M.; Urgiles, E. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    In this paper the authors demonstrate that nanoparticulate precursors coupled with spray deposition offers an attractive route into electronic materials with improved smoothness, density, and lower processing temperatures. Employing a metathesis approach, cadmium iodide was reacted with sodium telluride in methanol solvent, resulting in the formation of soluble NaI and insoluble CdTe nanoparticles. After appropriate chemical workup, methanol-capped CdTe colloids were isolated. CdTe thin film formation was achieved by spray depositing the nanoparticle colloids (25-75 {Angstrom} diameter) onto substrates at elevated temperatures (T = 280-440{degrees}C) with no further thermal treatment. These films were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Cubic CdTe phase formation was observed by XRD, with a contaminant oxide phase also detected. XPS analysis showed that CdTe films produced by this one-step method contained no Na or C and substantial O. AFM gave CdTe grain sizes of {approx}0.1-0.3 {mu}m for film sprayed at 400{degrees}C. A layer-by-layer film growth mechanism proposed for the one-step spray deposition of nanoparticle precursors will be discussed.

  20. Temperature dependent electroreflectance study of CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Raadik, T., E-mail: taavi.raadik@ttu.ee [Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Krustok, J.; Josepson, R.; Hiie, J. [Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Potlog, T.; Spalatu, N. [Moldova State University, A. Mateevici str. 60, MD-2009 Chisinau (Moldova, Republic of)

    2013-05-01

    Cadmium telluride is a promising material for large scale photovoltaic applications. In this paper we study CdS/CdTe heterojunction solar cells with electroreflectance spectroscopy. Both CdS and CdTe layers in solar cells were grown sequentially without intermediate processing by the close-space sublimation method. Electroreflectance measurements were performed in the temperature range of T = 100–300 K. Two solar cells were investigated with conversion efficiencies of 4.1% and 9.6%. The main focus in this work was to study the temperature dependent behavior of the broadening parameter and the bandgap energy of CdTe thin film in solar cells. Room temperature bandgap values of CdTe were E{sub g} = 1.499 eV and E{sub g} = 1.481 eV for higher and lower efficiency solar cells, respectively. Measured bandgap energies are lower than for single crystal CdTe. The formation of CdTe{sub 1−x}S{sub x} solid solution layer on the surface of CdTe is proposed as a possible cause of lower bandgap energies. - Highlights: ► Temperature dependent electroreflectance measurements of CdS/CdTe solar cells ► Investigation of junction properties between CdS and CdTe ► Formation of CdTe{sub 1−} {sub x}S{sub x} solid solution layer in the junction area.

  1. Work on the ATLAS semiconductor tracker barrel

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    Precision work is performed on the semiconductor tracker barrel of the ATLAS experiment. All work on these delicate components must be performed in a clean room so that impurities in the air, such as dust, do not contaminate the detector. The semiconductor tracker will be mounted in the barrel close to the heart of the ATLAS experiment to detect the path of particles produced in proton-proton collisions.

  2. Nitride semiconductor devices fundamentals and applications

    CERN Document Server

    Morkoç, Hadis

    2013-01-01

    This book gives a clear presentation of the necessary basics of semiconductor and device physics and engineering. It introduces readers to fundamental issues that will enable them to follow the latest technological research. It also covers important applications, including LED and lighting, semiconductor lasers, high power switching devices, and detectors. This balanced and up-to-date treatment makes the text an essential educational tool for both advanced students and professionals in the electronics industry.

  3. A study into the role of surface capping on energy transfer in metal cluster-semiconductor nanocomposites.

    Science.gov (United States)

    Bain, Dipankar; Paramanik, Bipattaran; Sadhu, Suparna; Patra, Amitava

    2015-12-28

    Metal cluster-semiconductor nanocomposite materials remain a frontier area of research for the development of optoelectronic, photovoltaic and light harvesting devices because metal nanoclusters and semiconductor QDs are promising candidates for photon harvesting. Here, we have designed well defined metal cluster-semiconductor nanostructures using different surface capped negatively charged Au25 nanoclusters (Au NCs) and positively charged cysteamine capped CdTe quantum dots using electrostatic interactions. The main focus of this article is to address the impact of surface capping agents on the photophysical properties of Au cluster-CdTe QD hybrid nanocomposites. Steady state and time resolved spectroscopic studies reveal that photoluminescence quenching, radiative and nonradiative rate, and energy transfer between Au nanoclusters and CdTe QDs have been influenced by the nature of the capping agent. We have calculated the energy transfer related parameters such as the overlap integral, distance between donor and acceptor, Förster distance, efficiency of energy transfer and rate of energy transfer from CdTe QDs to three different Au NCs. Photoluminescence quenching varies from 73% to 43% when changing the capping agents from bovine serum albumin (BSA) to glutathione (GSH). The efficiency of the energy transfer from CdTe QDs to BSA-capped Au NCs is found to be 83%, for Cys-capped Au NCs it was 46% and for GSH-capped Au NCs it was 35%. The efficiency depends on the number of Au clusters attached per QD. This reveals that the nature of capping ligands plays a crucial role in the energy transfer phenomena from CdTe QDs to Au NCs. Interesting findings reveal that the efficient energy transfer in metal cluster-semiconductor nanocomposites may open up new possibilities in designing artificial light harvesting systems for future applications.

  4. Semiconductor Optics

    CERN Document Server

    Klingshirn, Claus F

    2012-01-01

    This updated and enlarged new edition of Semiconductor Optics provides an introduction to and an overview of semiconductor optics from the IR through the visible to the UV, including linear and nonlinear optical properties, dynamics, magneto and electrooptics, high-excitation effects and laser processes, some applications, experimental techniques and group theory. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered extend from physics to materials science and optoelectronics. Significantly updated chapters add coverage of current topics such as electron hole plasma, Bose condensation of excitons and meta materials. Over 120 problems, chapter introductions and a detailed index make it the key textbook for graduate students in physics. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered ...

  5. Search for WW and WZ production in lepton, neutrino plus jets final states at CDF Run II and Silicon module production and detector control system for the ATLAS SemiConductor Tracker

    Energy Technology Data Exchange (ETDEWEB)

    Sfyrla, Anna [Univ. of Geneva (Switzerland)

    2008-03-10

    In the first part of this work, we present a search for WW and WZ production in charged lepton, neutrino plus jets final states produced in p$\\bar{p}$ collisions with √s = 1.96 TeV at the Fermilab Tevatron, using 1.2 fb-1 of data accumulated with the CDF II detector. This channel is yet to be observed in hadron colliders due to the large singleWplus jets background. However, this decay mode has a much larger branching fraction than the cleaner fully leptonic mode making it more sensitive to anomalous triple gauge couplings that manifest themselves at higher transverse W momentum. Because the final state is topologically similar to associated production of a Higgs boson with a W, the techniques developed in this analysis are also applicable in that search. An Artificial Neural Network has been used for the event selection optimization. The theoretical prediction for the cross section is σWW/WZtheory x Br(W → ℓv; W/Z → jj) = 2.09 ± 0.14 pb. They measured NSignal = 410 ± 212(stat) ± 102(sys) signal events that correspond to a cross section σWW/WZ x Br(W → ℓv; W/Z → jj) = 1.47 ± 0.77(stat) ± 0.38(sys) pb. The 95% CL upper limit to the cross section is estimated to be σ x Br(W → ℓv; W/Z → jj) < 2.88 pb. The second part of the present work is technical and concerns the ATLAS SemiConductor Tracker (SCT) assembly phase. Although technical, the work in the SCT assembly phase is of prime importance for the good performance of the detector during data taking. The production at the University of Geneva of approximately one third of the silicon microstrip end-cap modules is presented. This collaborative effort of the university of Geneva group that lasted two years, resulted in 655 produced modules, 97% of which were good modules, constructed within the mechanical and electrical specifications and delivered in the SCT collaboration for assembly on the end-cap disks. The SCT end-caps and barrels

  6. Cryogenic semiconductor high-intensity radiation monitors

    CERN Document Server

    Palmieri, V G; Borer, K; Casagrande, L; Da Vià, C; Devine, S R H; Dezillie, B; Esposito, A; Granata, V; Hauler, F; Jungermann, L; Li, Z; Lourenço, C; Niinikoski, T O; O'Shea, V

    2003-01-01

    This paper describes a novel technique to monitor high-intensity particle beams by means of a semiconductor detector. It consists of cooling a semiconductor detector down to cryogenic temperature to suppress the thermally generated leakage current and to precisely measure the integrated ionization signal. It will be shown that such a device provides very good linearity and a dynamic range wider than is possible with existing techniques. Moreover, thanks to the Lazarus effect, extreme radiation hardness can be achieved providing in turn absolute intensity measurements against precise calibration of the device at low beam flux.

  7. CdTe Thin Film Solar Cells and Modules Tutorial; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    Albin, David S.

    2015-06-13

    This is a tutorial presented at the 42nd IEEE Photovoltaics Specialists Conference to cover the introduction, background, and updates on CdTe cell and module technology, including CdTe cell and module structure and fabrication.

  8. Particlc detectors. Foundations and applications; Teilchendetektoren. Grundlagen und Anwendungen

    Energy Technology Data Exchange (ETDEWEB)

    Kolanoski, Hermann; Wermes, Norbert

    2016-08-01

    The following topics are dealt with: Interaction of particles with matter, motion of charge carriers in electric and magnetic fields, signal generation by moving charges, non-electronic detectors, gas-filled detectors, semiconductor detectors, track reconstruction and momentum measurement, photodetectors, Cherenkov detectors, transition-radiation detectors, scintillation detectors, particle identification, calorimeters, detection of cosmic particles, signal processing and noise, trigger and data acquisition systems. (HSI)

  9. Measurement of mobility and lifetime of electrons and holes in a Schottky CdTe diode

    Science.gov (United States)

    Ariño-Estrada, G.; Chmeissani, M.; de Lorenzo, G.; Kolstein, M.; Puigdengoles, C.; García, J.; Cabruja, E.

    2014-12-01

    We report on the measurement of drift properties of electrons and holes in a CdTe diode grown by the travelling heating method (THM). Mobility and lifetime of both charge carriers has been measured independently at room temperature and fixed bias voltage using charge integration readout electronics. Both electrode sides of the detector have been exposed to a 241Am source in order to obtain events with full contributions of either electrons or holes. The drift time has been measured to obtain the mobility for each charge carrier. The Hecht equation has been employed to evaluate the lifetime. The measured values for μτe/h (mobility-lifetime product) are in agreement with earlier published data.

  10. 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.

  11. Comparative study of CdTe sources used for deposition of CdTe thin films by close spaced sublimation technique

    Directory of Open Access Journals (Sweden)

    Wagner Anacleto Pinheiro

    2006-03-01

    Full Text Available Unlike other thin film deposition techniques, close spaced sublimation (CSS requires a short source-substrate distance. The kind of source used in this technique strongly affects the control of the deposition parameters, especially the deposition rate. When depositing CdTe thin films by CSS, the most common CdTe sources are: single-crystal or polycrystalline wafers, powders, pellets or pieces, a thick CdTe film deposited onto glass or molybdenum substrate (CdTe source-plate and a sintered CdTe powder. In this work, CdTe thin films were deposited by CSS technique from different CdTe sources: particles, powder, compact powder, a paste made of CdTe and propylene glycol and source-plates (CdTe/Mo and CdTe/glass. The largest deposition rate was achieved when a paste made of CdTe and propylene glycol was used as the source. CdTe source-plates led to lower rates, probably due to the poor heat transmission, caused by the introduction of the plate substrate. The results also showed that compacting the powder the deposition rate increases due to the better thermal contact between powder particles.

  12. Semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Ito, K.; Shyuue, M.

    1982-09-25

    A distributed feedback semiconductor laser is proposed which generates several beams with equal wavelengths in different directions. For this purpose, 1 millimeter grooves are cut into the surface of an n-type conductance GaAs plate in three different directions; these grooves form a diffraction grating. The center of this plate has no grooves and is bombarded by an He/Ne laser beam. The diffraction gratings provide resonance properties and generate laser beams with wavelengths of 8850, 9000 and 9200 angstroms.

  13. Hard X-ray polarimetry with Caliste, a high performance CdTe based imaging spectrometer

    Science.gov (United States)

    Antier, S.; Ferrando, P.; Limousin, O.; Caroli, E.; Curado da Silva, R. M.; Blondel, C.; Chipaux, R.; Honkimaki, V.; Horeau, B.; Laurent, P.; Maia, J. M.; Meuris, A.; Del Sordo, S.; Stephen, J. B.

    2015-06-01

    Since the initial exploration of the X- and soft γ-ray sky in the 60's, high-energy celestial sources have been mainly characterized through imaging, spectroscopy and timing analysis. Despite tremendous progress in the field, the radiation mechanisms at work in sources such as neutrons stars, black holes, and Active Galactic Nuclei are still unclear. The polarization state of the radiation is an observational parameter which brings key additional information about the physical processes in these high energy sources, allowing the discrimination between competing models which may otherwise all be consistent with other types of measurement. This is why most of the projects for the next generation of space missions covering the few tens of keV to the MeV region require a polarization measurement capability. A key element enabling this capability, in this energy range, is a detector system allowing the identification and characterization of Compton interactions as they are the main process at play. The compact hard X-ray imaging spectrometer module, developed in CEA with the generic name of "Caliste" module, is such a detector. In this paper, we present experimental results for two types of Caliste-256 modules, one based on a CdTe crystal, the other one on a CdZnTe crystal, which have been exposed to linearly polarized beams at the European Synchrotron Radiation Facility (ESRF). These results, obtained at 200 and 300 keV, demonstrate the capability of these modules to detect Compton events and to give an accurate determination of the polarization parameters (polarization angle and fraction) of the incoming beam. For example, applying an optimized selection to our data set, equivalent to select 90° Compton scattered interactions in the detector plane, we find a modulation factor Q of 0.78 ± 0.06 in the 200-300 keV range. The polarization angle and fraction are derived with accuracies of approximately 1° and 5 % respectively for both CdZnTe and CdTe crystals. The

  14. Position-sensitive superconductor detectors

    Science.gov (United States)

    Kurakado, M.; Taniguchi, K.

    2016-12-01

    Superconducting tunnel junction (STJ) detectors and superconducting transition- edge sensors (TESs) are representative superconductor detectors having energy resolutions much higher than those of semiconductor detectors. STJ detectors are thin, thereby making it suitable for detecting low-energy X rays. The signals of STJ detectors are more than 100 times faster than those of TESs. By contrast, TESs are microcalorimeters that measure the radiation energy from the change in the temperature. Therefore, signals are slow and their time constants are typically several hundreds of μs. However, TESs possess excellent energy resolutions. For example, TESs have a resolution of 1.6 eV for 5.9-keV X rays. An array of STJs or TESs can be used as a pixel detector. Superconducting series-junction detectors (SSJDs) comprise multiple STJs and a single-crystal substrate that acts as a radiation absorber. SSJDs are also position sensitive, and their energy resolutions are higher than those of semiconductor detectors. In this paper, we give an overview of position-sensitive superconductor detectors.

  15. 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...

  16. 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.)

  17. 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...

  18. Resetting the Defect Chemistry in CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, Wyatt K.; Burst, James; Albin, David; Colegrove, Eric; Moseley, John; Duenow, Joel; Farrell, Stuart; Moutinho, Helio; Reese, Matt; Johnston, Steve; Barnes, Teresa; Perkins, Craig; Guthrey, Harvey; Al-Jassim, Mowafak

    2015-06-14

    CdTe cell efficiencies have increased from 17% to 21% in the past three years and now rival polycrystalline Si [1]. Research is now targeting 25% to displace Si, attain costs less than 40 cents/W, and reach grid parity. Recent efficiency gains have come largely from greater photocurrent. There is still headroom to lower costs and improve performance by increasing open-circuit voltage (Voc) and fill factor. Record-efficiency CdTe cells have been limited to Voc <; 880 mV, whereas GaAs can attain Voc of 1.10 V with a slightly smaller bandgap [2,3]. To overcome this barrier, we seek to understand and increase lifetime and carrier concentration in CdTe. In polycrystalline structures, lifetime can be limited by interface and grain-boundary recombination, and attaining high carrier concentration is complicated by morphology.

  19. Study of Back Contacts for CdTe Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    ZnTe/ZnTe∶Cu layer is used as a complex back contact. The parameters of CdTe solar cells with and without the complex back contacts are compared. The effects of un-doped layer thickness, doped concentration and post-deposition annealing temperature of the complex layer on solar cells performance are investigated.The results show that ZnTe/ZnTe∶Cu layer can improve back contacts and largely increase the conversion efficiency of CdTe solar cells. Un-doped layer and post-deposition annealing of high temperature can increase open voltage. Using the complex back contact, a small CdTe cell with fill factor of 73.14% and conversion efficiency of 12.93% is obtained.

  20. Recent advances in thin film CdTe solar cells

    Science.gov (United States)

    Ferekides, Chris S.; Ceekala, Vijaya; Dugan, Kathleen; Killian, Lawrence; Oman, Daniel; Swaminathan, Rajesh; Morel, Don

    1996-01-01

    CdTe thin film solar cells have been fabricated on a variety of glass substrates (borosilicate and soda lime). The CdS films were deposited to a thickness of 500-2000 Å by the chemical bath deposition (CBD), rf sputtering, or close spaced sublimation (CSS) processes. The CdTe films were deposited by CSS in the temperature range of 450-625 °C. The main objective of this work is to fabricate high efficiency solar cells using processes that can meet low cost manufacturing requirements. In an attempt to enhance the blue response of the CdTe cells, ZnS films have also been prepared (CBD, rf sputtering, CSS) as an alternative window layer to CdS. Device behavior has been found to be consistent with a recombination model.

  1. Development and performance of a gamma-ray imaging detector

    Science.gov (United States)

    Gálvez, J. L.; Hernanz, M.; Álvarez, J. M.; La Torre, M.; Álvarez, L.; Karelin, D.; Lozano, M.; Pellegrini, G.; Ullán, M.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2012-09-01

    In the last few years we have been working on feasibility studies of future instruments in the gamma-ray range, from several keV up to a few MeV. The innovative concept of focusing gamma-ray telescopes in this energy range, should allow reaching unprecedented sensitivities and angular resolution, thanks to the decoupling of collecting area and detector volume. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN). In order to achieve the needed performance, a gamma-ray imaging detector with mm spatial resolution and large enough efficiency is required. In order to fulfill the combined requirement of high detection efficiency with good spatial and energy resolution, an initial prototype of a gamma-ray imaging detector based on CdTe pixel detectors is being developed. It consists of a stack of several layers of CdTe detectors with increasing thickness, in order to enhance the gamma-ray absorption in the Compton regime. A CdTe module detector lies in a 11 x 11 pixel detector with a pixel pitch of 1mm attached to the readout chip. Each pixel is bump bonded to a fan-out board made of alumina (Al2O3) substrate and routed to the corresponding input channel of the readout ASIC to measure pixel position and pulse height for each incident gamma-ray photon. We will report the main features of the gamma-ray imaging detector performance such as the energy resolution for a set of radiation sources at different operating temperatures.

  2. Development of a CZT drift ring detector for X and γ ray spectroscopy

    Science.gov (United States)

    Alruhaili, A.; Sellin, P. J.; Lohstroh, A.; Boothman, V.; Veeramani, P.; Veale, M. C.; Sawhney, K. J. S.; Kachkanov, V.

    2015-04-01

    CdTe and CZT detectors are considered better choices for high energy γ and X-ray spectroscopy in comparison to Si and HPGe detectors due to their good quantum efficiency and room temperature operation. The performance limitations in CdTe and CZT detectors are mainly associated with poor hole transport and trapping phenomena. Among many techniques that can be used to eliminate the effect of the poor charge transport properties of holes in CdTe and CZT material, the drift ring technique shows promising results. In this work, the performance of a 2.3 mm thick CZT drift ring detector is investigated. Spatially resolved measurements were carried out with an X-ray microbeam (25 and 75 keV) at the Diamond Light Source synchrotron to study the response uniformity and extent of the active area. Higher energy photon irradiation was also carried out at up to 662 keV using different radioisotopes to complement the microbeam data. Different biasing schemes were investigated in terms of biasing the cathode rear electrode (bulk field) and the ring electrodes (lateral fields). The results show that increasing the bulk field with fixed-ratio ring biases and lateral fields with fixed bulk fields increase the active area of the device significantly, which contrasts with previous studies in CdTe, where only an increasing lateral field resulted in an improvement of device performance. This difference is attributed to the larger thickness of the CZT device reported here.

  3. Effects of Antimony Doping in Polycrystalline CdTe Thin-Film Solar Cells

    Science.gov (United States)

    Okamoto, Tamotsu; Ikeda, Shigeyuki; Nagatsuka, Satsuki; Hayashi, Ryoji; Yoshino, Kaoru; Kanda, Yohei; Noda, Akira; Hirano, Ryuichi

    2012-10-01

    The effects of antimony (Sb) doping of the CdTe layer in the CdTe solar cells were investigated using Sb-doped CdTe powders as source materials for CdTe deposition by the close-spaced sublimation (CSS) method. Conversion efficiency increased with increasing Sb concentration below 1×1018 cm-3, mainly owing to the improvement of the fill factor. Secondary ion microprobe mass spectrometry (SIMS) depth profile revealed that the Sb impurities at a concentration of approximately 1×1016 cm-3 were incorporated into the CdTe layer when using the Sb-doped CdTe source of 1×1018 cm-3. The observation of surface morphology showed that the grain sizes were improved by Sb addition. Therefore, the improved performance upon Sb addition to CdTe solar cells was probably due to the improvements in crystallinity, such as increased grain size.

  4. CdTe nano-structures for photovoltaic devices

    OpenAIRE

    Corregidor, V.; Alves, L. C.; FRANCO, N.; Barreiros, Maria Alexandra; Sochinskii, N. V.; Alves, E

    2013-01-01

    CdTe nano-structures with diameter of ∼100 nm and variable length (200–600 nm) were fabricated on glass substrates covered with conductive buffer layers such as NiCr, ZAO (ZnO:Al2O3 + Ta2O5) or TiPd alloys. The fabrication process consisted of the starting vapour deposition of metal catalyst dropped layer followed by the isothermal catalyst-prompted vapour growth of CdTe nano-structured layer of controllable shape and surface filling. The effect of buffer layers on the crystallographic orient...

  5. Optical measurements for excitation of CdTe quantum dots

    Science.gov (United States)

    Vladescu, Marian; Feies, Valentin; Schiopu, Paul; Craciun, Alexandru; Grosu, Neculai; Manea, Adrian

    2016-12-01

    The paper presents the experimental results obtained using a laboratory setup installation for fluorescence excitation of CdTe QDs used as biomarkers for clinical diagnostics. Quantum Dots (QDs) made of Cadmium Telluride (CdTe), are highly fluorescent and they are used as robust biomarkers. Generally, QDs are referred to as the zero-dimensional colloidal crystals that possess strong size dependence and multi-colored luminescence properties. Along with its intrinsic features, such as sharp and symmetric emission, photo-stability and high quantum yields, QDs play a vital role in various applications, namely the identification of the chemical moieties, clinical diagnostics, optoelectronics, bio-imaging and bio-sensing1.

  6. The principle and application of metal oxide semiconductor field effect transistor detector during radiotherapy%金属氧化物半导体场效应晶体管剂量探测器的工作原理及在放射治疗中的应用

    Institute of Scientific and Technical Information of China (English)

    倪园园; 涂彧

    2008-01-01

    Metal oxide semiconductor field effect transistor (MOSFET) detector was used to measure radiation dose in space initially, and it was applied to medical domain in recent years. MOSFET detector had extent prospect in clinical field because it had the advantages that other nomal detectors couldn' t compare with. This article introduced the application of MOSFET detector in radiotherapy by summarizing its basic principle, the principle of measuring dose and the relative characteristics.%金属氧化物半导体场效应晶体管(MOSFET)探测器原用于空间系统的辐射测量,近几年才引入到医学领域.由于该探测器具有普通探测设备无法比拟的优点,因此在临床有广泛的应用前景.通过概述MOSFET 20探测器的基本工作原理、剂量探测原理及其相关特性,介绍了MOSFET探测器在放射治疗中的应用.

  7. Materials chemistry. Composition-matched molecular "solders" for semiconductors.

    Science.gov (United States)

    Dolzhnikov, Dmitriy S; Zhang, Hao; Jang, Jaeyoung; Son, Jae Sung; Panthani, Matthew G; Shibata, Tomohiro; Chattopadhyay, Soma; Talapin, Dmitri V

    2015-01-23

    We propose a general strategy to synthesize largely unexplored soluble chalcogenidometallates of cadmium, lead, and bismuth. These compounds can be used as "solders" for semiconductors widely used in photovoltaics and thermoelectrics. The addition of solder helped to bond crystal surfaces and link nano- or mesoscale particles together. For example, CdSe nanocrystals with Na2Cd2Se3 solder was used as a soluble precursor for CdSe films with electron mobilities exceeding 300 square centimeters per volt-second. CdTe, PbTe, and Bi2Te3 powders were molded into various shapes in the presence of a small additive of composition-matched chalcogenidometallate or chalcogel, thus opening new design spaces for semiconductor technologies.

  8. Comparative study of CdTe sources used for deposition of CdTe thin films by close spaced sublimation technique

    OpenAIRE

    Pinheiro,Wagner Anacleto; Falcão, Vivienne Denise; Cruz,Leila Rosa de Oliveira; Ferreira,Carlos Luiz

    2006-01-01

    Unlike other thin film deposition techniques, close spaced sublimation (CSS) requires a short source-substrate distance. The kind of source used in this technique strongly affects the control of the deposition parameters, especially the deposition rate. When depositing CdTe thin films by CSS, the most common CdTe sources are: single-crystal or polycrystalline wafers, powders, pellets or pieces, a thick CdTe film deposited onto glass or molybdenum substrate (CdTe source-plate) and a sintered C...

  9. Identification of Ag-acceptors in $^{111}\\!$Ag $^{111}\\!$Cd doped ZnTe and CdTe

    CERN Document Server

    Hamann, J; Deicher, M; Filz, T; Lany, S; Ostheimer, V; Strasser, F; Wolf, H; Wichert, T

    2000-01-01

    Nominally undoped ZnTe and CdTe crystals were implanted with radioactive $^{111}\\!$Ag, which decays to $^{111}\\!$Cd, and investigated by photoluminescence spectroscopy (PL). In ZnTe, the PL lines caused by an acceptor level at 121 meV are observed: the principal bound exciton (PBE) line, the donor-acceptor pair (DAP) band, and the two-hole transition lines. In CdTe, the PBE line and the DAP band that correspond to an acceptor level at 108 meV appear. Since the intensities of all these PL lines decrease in good agreement with the half-life of $^{111}\\!$Ag of 178.8 h, both acceptor levels are concluded to be associated with defects containing a single Ag atom. Therefore, the earlier assignments to substitutional Ag on Zn- and Cd-lattice sites in the respective II-VI semiconductors are confirmed. The assignments in the literature of the S$_1$, S$_2$, and S$_3$ lines in ZnTe and the X$\\scriptstyle^\\textrm{Ag}_{1}\\,\\,,$ X$\\scriptstyle^\\textrm{Ag}_{2}$/ C$\\scriptstyle^\\textrm{Ag}_{1}\\,$ and C$\\scriptstyle^\\textrm{...

  10. High throughput combinatorial screening of semiconductor materials

    Science.gov (United States)

    Mao, Samuel S.

    2011-11-01

    This article provides an overview of an advanced combinatorial material discovery platform developed recently for screening semiconductor materials with properties that may have applications ranging from radiation detectors to solar cells. Semiconductor thin-film libraries, each consisting of 256 materials of different composition arranged into a 16×16 matrix, were fabricated using laser-assisted evaporation process along with a combinatorial mechanism to achieve variations. The composition and microstructure of individual materials on each thin-film library were characterized with an integrated scanning micro-beam x-ray fluorescence and diffraction system, while the band gaps were determined by scanning optical reflection and transmission of the libraries. An ultrafast ultraviolet photon-induced charge probe was devised to measure the mobility and lifetime of individual thin-film materials on semiconductor libraries. Selected results on the discovery of semiconductors with desired band gaps and transport properties are illustrated.

  11. Adsorption properties of CdS-CdTe system semiconductors

    Science.gov (United States)

    Kirovskaya, I. A.; Nor, P. E.

    2013-12-01

    The adsorption of carbon(II) oxide and ammonia on nanofilms of solid solutions and binary compounds of the CdS-CdTe system is studied by means of piezoquartz microweighing, FTIR IR, and measuring electroconductivity. Allowing for the conditions and composition of semiconductor systems, we determine the mechanisms and principles of adsorption processes by analyzing the α p = f( T), α T = f( p), and α T = f( t) experimental dependences; IR spectra; the thermodynamic and kinetic characteristics of adsorption; the acid-base, electrophysical, and other characteristics of adsorbents; the electron nature of adsorbate molecules; and the obtained acid-base characteristics: the composition and adsorption characteristics and composition state diagrams. Previous statements on the nature and retention of local active centers responsible for adsorption and catalytic processes upon changes in their habitus and composition (as components of systems of the AIIIBV-AIIBVI and AIIBVI-AIIBVI types) on the surface of diamond-like semiconductors are confirmed. Specific features of the behavior of (CdS) x (CdTe)1 - x solid solutions are identified in addition to general features with binary compounds (CdS, CdTe), as is demonstrated by the presence of critical points on acid-base characteristics-composition and adsorption characteristics-composition diagrams. On the basis of these diagrams, the most active adsorbents (with respect to CO and NH3) used in designing highly sensitive and selective sensors are identified.

  12. Combining two major ATLAS inner detector components

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    The semiconductor tracker is inserted into the transition radiation tracker for the ATLAS experiment at the LHC. These make up two of the three major components of the inner detector. They will work together to measure the trajectories produced in the proton-proton collisions at the centre of the detector when the LHC is switched on in 2008.

  13. Semiconductor laser. Halbleiterlaser

    Energy Technology Data Exchange (ETDEWEB)

    Wuenstel, K.; Gohla, B.; Tegude, F.; Luz, G.; Hildebrand, O.

    1987-08-27

    A highly modulable semiconductor laser and a process for its manufacture are described. The semiconductor laser has a substrate, a stack of semiconductor layers and electrical contacts. To reduce the capacity, the width of the stack of semiconductor layers is reduced at the sides by anisotropic etching. The electrical contacts are situated on the same side of the substrate and are applied in the same stage of the process. The semiconductor laser is suitable for monolithic integration in other components.

  14. Simultaneous shunt protection and back contact formation for CdTe solar cells with single wall carbon nanotube layers

    Science.gov (United States)

    Phillips, Adam B.; Khanal, Rajendra R.; Song, Zhaoning; Watthage, Suneth C.; Kormanyos, Kenneth R.; Heben, Michael J.

    2015-12-01

    Thin film photovoltaic (PV) devices and modules prepared by commercial processes can be severely compromised by through-device low resistance electrical pathways. The defects can be due to thin or missing semiconductor material, metal diffusion along grain boundaries, or areas containing diodes with low turn-on potentials. We report the use of single wall carbon nanotube (SWCNT) layers to enable both protection against these defects and back contact formation for CdTe PV devices. Samples prepared with a SWCNT back contact exhibited good efficiency and did not require shunt protection, while devices prepared without shunt protection using a standard metal back contact performed poorly. We describe the mechanism by which the SWCNT layer functions. In addition to avoiding the need for shunt protection by other means, the SWCNT film also provides a route to higher short circuit currents.

  15. Radiative and interfacial recombination in CdTe heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Swartz, C. H., E-mail: craig.swartz@txstate.edu; Edirisooriya, M.; LeBlanc, E. G.; Noriega, O. C.; Jayathilaka, P. A. R. D.; Ogedengbe, O. S.; Hancock, B. L.; Holtz, M.; Myers, T. H. [Materials Science, Engineering, and Commercialization Program, Texas State University, 601 University Dr., San Marcos, Texas 78666 (United States); Zaunbrecher, K. N. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Mississippi RSF200, Golden, Colorado 80401 (United States)

    2014-12-01

    Double heterostructures (DH) were produced consisting of a CdTe film between two wide band gap barriers of CdMgTe alloy. A combined method was developed to quantify radiative and non-radiative recombination rates by examining the dependence of photoluminescence (PL) on both excitation intensity and time. The measured PL characteristics, and the interface state density extracted by modeling, indicate that the radiative efficiency of CdMgTe/CdTe DHs is comparable to that of AlGaAs/GaAs DHs, with interface state densities in the low 10{sup 10 }cm{sup −2} and carrier lifetimes as long as 240 ns. The radiative recombination coefficient of CdTe is found to be near 10{sup −10} cm{sup 3}s{sup −1}. CdTe film growth on bulk CdTe substrates resulted in a homoepitaxial interface layer with a high non-radiative recombination rate.

  16. Intracavity CdTe modulators for CO2 lasers.

    Science.gov (United States)

    Kiefer, J. E.; Nussmeier, T. A.; Goodwin, F. E.

    1972-01-01

    The use of cadmium telluride as an electrooptic material for intracavity modulation of CO2 lasers is described. Included are the predicted and measured effects of CdTe intracavity modulators on laser performance. Coupling and frequency modulation are discussed and experimental results compared with theoretically predicted performance for both techniques. Limitations on the frequency response of the two types of modulation are determined.

  17. Thermal stability of substitutional ag in CdTe

    NARCIS (Netherlands)

    Jahn, SG; Hofsass, H; Restle, M; Ronning, C; Quintel, H; BharuthRam, K; Wahl, U

    1996-01-01

    The thermal stability of substitutional Ag in CdTe was deduced from lattice location measurements at different temperatures. Substitutional Ag probe atoms were generated via transmutation doping from radioactive Cd isotopes. The lattice sites of Ag isotopes were determined by measuring the channelin

  18. Catalytic growth of CdTe nanowires by closed space sublimation method

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Gwangseok; Jung, Younghun [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Chun, Seungju; Kim, Donghwan [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Kim, Jihyun, E-mail: hyunhyun7@korea.ac.kr [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    2013-11-01

    CdTe nano-/micro-structures with various morphologies were grown by using the closed space sublimation (CSS) method on a sapphire substrate by Au-catalyzed vapor–liquid–solid (VLS) mechanism. Length, diameter, and morphology of the CdTe nano-/micro-structures depended on the growth time and temperature gradient between the substrate and powdered CdTe source. Scanning electron microscopy images showed that an Au catalyst droplet existed at the tips of CdTe nanowires, which confirms that CdTe nanowires were grown by an Au-catalyzed VLS mechanism. Also, we observed that the two-dimensional CdTe film layer initially formed before the growth of the CdTe nano-/micro-wires. The optical and structural properties of CdTe nano-/micro-structures were characterized by X-ray diffraction technique and micro-Raman spectroscopy. Our study demonstrates that diverse CdTe nano-/micro-structures can be fabricated by using Au-catalyzed VLS growth process in a simple CSS chamber by controlling the temperature gradient and growth time. - Highlights: • We demonstrated CdTe nanowires using closed space sublimation method. • Au-catalyst droplets at the tips confirmed vapor–liquid–solid mechanism. • Diameters and lengths increased with increasing temperature gradient and time.

  19. Novel applications of semiconductor nanocrystals

    Science.gov (United States)

    Lau, Pick Chung

    We have investigated ways of modifying a common water soluble CdTe NCs to become non-photobleaching. Such NCs are capable of responding reversibly to an inter-switching of the oxygen and argon environments over multiple hours of photoexcitation. They are found to quench upon exposure to oxygen, but when the system is purged with argon, their photoluminescence (PL) revives to the original intensity. Such discovery could potentially be used as oxygen nanosensors. These PL robust CdTe NCs immobilized on glass substrates also exhibit significant changes in their PL when certain organic/bio molecules are placed in their vicinity (nanoscale). This novel technique also known as NC-organic molecule close proximity imaging (NC-cp imaging) has found to provide contrast ratio greater by a factor of 2-3 compared to conventional fluorescence imaging technique. PL of NCs is recoverable upon removal of these organic molecules, therefore validating these NCs as potential all-optical organic molecular nanosensors and, upon optimization, ultimately serving as point detectors for purposes of super-resolution microscopy (with proper instrumentation). No solvents are required for this sensing mechanism since all solutions were dried under argon flow. Furthermore, core graded shell CdSe/CdSexS1-x/CdS giant nanocrystal (g-NCs) were found to have very robust PL temperature response. At a size of 10.2 nm in diameter, these g-NCs undergo PL drop of only 30% at 355K (normalized to PL intensity at 85K). In comparison, the core step shells CdSe/CdS g-NCs at the same diameter exhibit 80% PL drop at 355K. Spectral shifting and broadening were acquired and found to be 5-10 times and 2-4 times smaller respectively than the standard CdSe core and CdSe/CdS core shell NCs. It is also discovered that these core graded shell g-NCs are largely nonblinking and have insignificant photoluminescence decay even after exciting the samples at very high irradiance (44 kW/cm2) for over an hour. These types of g

  20. Microwave studies on the dielectric properties of Sm{sup 3+} and Sm{sup 3+}/CdTe doped sol-gel silica glasses

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, Siby; Rejikumar, P.R. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India); Yohannan, Jaimon; Mathew, K.T. [Department of Electronics, Cochin University of Science and Technology, Cochin 682022 (India); Unnikrishnan, N.V. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India)], E-mail: nvu50@yahoo.co.in

    2008-08-25

    Complex permittivity and conductivity studies of Samarium and Samarium/semiconductor cadmium telluride sol-gel silica glass samples were done. We use cavity perturbation technique at S band frequencies using TE{sub 10p} Mode. Structural evolution of the matrix on annealing is discussed based on FTIR analysis/XRD power diffraction. In cavity perturbation technique dielectric parameters like complex permittivity and conductivity are determined by measuring changes in resonant frequency due to small perturbation inside the cavity produced by the introduction of the samples. The addition of the semiconductor along with the samarium was found to lower the permittivity, loss factor and conductivity. Variations of permittivity values with annealing temperature find applications in IC Technology, optic fibre communication, etc. The Sm{sup 3+}/CdTe doped glasses can also be used in the fabrication of new and improved materials for microwave electronic circuits and in electromagnetic shielding devices.

  1. Electrostatic assembles and optical properties of Au CdTe QDs and Ag/Au CdTe QDs

    Science.gov (United States)

    Yang, Dongzhi; Wang, Wenxing; Chen, Qifan; Huang, Yuping; Xu, Shukun

    2008-09-01

    Au-CdTe and Ag/Au-CdTe assembles were firstly investigated through the static interaction between positively charged cysteamine-stabilized CdTe quantum dots (QDs) and negatively charged Au or core/shell Ag/Au nano-particles (NCs). The CdTe QDs synthesized in aqueous solution were capped with cysteamine which endowed them positive charges on the surface. Both Au and Ag/Au NCs were prepared through reducing precursors with gallic acid obtained from the hydrolysis of natural plant poly-phenols and favored negative charges on the surface of NCs. The fluorescence spectra of CdTe QDs exhibited strong quenching with the increase of added Au or Ag/Au NCs. Railey resonance scattering spectra of Au or Ag/Au NCs increased firstly and decreased latter with the concentration of CdTe QDs, accompanied with the solution color changing from red to purple and colorless at last. Experimental results on the effects of gallic acid, chloroauric acid tetrahydrate and other reagents demonstrated the static interaction occurred between QDs and NCs. This finding reveals the possibilities to design and control optical process and electromagnetic coupling in hybrid structures.

  2. Hard X-ray polarimetry with Caliste, a high performance CdTe based imaging spectrometer

    CERN Document Server

    Antier, S; Limousin, O; Caroli, E; da Silva, R M Curado; Blondel, C; Chipaux, R; Honkimaki, V; Horeau, B; Laurent, P; Maia, J M; Meuris, A; Del Sordo, S; Stephen, J B

    2015-01-01

    Since the initial exploration of soft gamma-ray sky in the 60's, high-energy celestial sources have been mainly characterized through imaging, spectroscopy and timing analysis. Despite tremendous progress in the field, the radiation mechanisms at work in sources such as neutrons stars and black holes are still unclear. The polarization state of the radiation is an observational parameter which brings key additional information about the physical process. This is why most of the projects for the next generation of space missions covering the tens of keV to the MeV region require a polarization measurement capability. A key element enabling this capability is a detector system allowing the identification and characterization of Compton interactions as they are the main process at play. The hard X-ray imaging spectrometer module, developed in CEA with the generic name of Caliste module, is such a detector. In this paper, we present experimental results for two types of Caliste-256 modules, one based on a CdTe cr...

  3. Direct Measurement of Mammographic X-Ray Spectra with a Digital CdTe Detection System

    Directory of Open Access Journals (Sweden)

    Giuseppe Raso

    2012-06-01

    Full Text Available In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP system, for high-rate X-ray spectroscopy in mammography (1–30 keV. The DPP system performs a height and shape analysis of the detector pulses, sampled and digitized by a 14-bit, 100 MHz ADC. We show the results of the characterization of the detection system both at low and high photon counting rates by using monoenergetic X-ray sources and a nonclinical X-ray tube. The detection system exhibits excellent performance up to 830 kcps with an energy resolution of 4.5% FWHM at 22.1 keV. Direct measurements of clinical molybdenum X-ray spectra were carried out by using a pinhole collimator and a custom alignment device. A comparison with the attenuation curves and the half value layer values, obtained from the measured and simulated spectra, from an ionization chamber and from a solid state dosimeter, also shows the accuracy of the measurements. These results make the proposed detection system a very attractive tool for both laboratory research, calibration of dosimeters and advanced quality controls in mammography.

  4. Characterization of CdTe Films Deposited at Various Bath Temperatures and Concentrations Using Electrophoretic Deposition

    Directory of Open Access Journals (Sweden)

    Zulkarnain Zainal

    2012-05-01

    Full Text Available CdTe film was deposited using the electrophoretic deposition technique onto an ITO glass at various bath temperatures. Four batch film compositions were used by mixing 1 to 4 wt% concentration of CdTe powder with 10 mL of a solution of methanol and toluene. X-ray Diffraction analysis showed that the films exhibited polycrystalline nature of zinc-blende structure with the (111 orientation as the most prominent peak. From the Atomic Force Microscopy, the thickness and surface roughness of the CdTe film increased with the increase of CdTe concentration. The optical energy band gap of film decreased with the increase of CdTe concentration, and with the increase of isothermal bath temperature. The film thickness increased with respect to the increase of CdTe concentration and bath temperature, and following, the numerical expression for the film thickness with respect to these two variables has been established.

  5. Characterization of CdTe films deposited at various bath temperatures and concentrations using electrophoretic deposition.

    Science.gov (United States)

    Daud, Mohd Norizam Md; Zakaria, Azmi; Jafari, Atefeh; Ghazali, Mohd Sabri Mohd; Abdullah, Wan Rafizah Wan; Zainal, Zulkarnain

    2012-01-01

    CdTe film was deposited using the electrophoretic deposition technique onto an ITO glass at various bath temperatures. Four batch film compositions were used by mixing 1 to 4 wt% concentration of CdTe powder with 10 mL of a solution of methanol and toluene. X-ray Diffraction analysis showed that the films exhibited polycrystalline nature of zinc-blende structure with the (111) orientation as the most prominent peak. From the Atomic Force Microscopy, the thickness and surface roughness of the CdTe film increased with the increase of CdTe concentration. The optical energy band gap of film decreased with the increase of CdTe concentration, and with the increase of isothermal bath temperature. The film thickness increased with respect to the increase of CdTe concentration and bath temperature, and following, the numerical expression for the film thickness with respect to these two variables has been established.

  6. CdTe microwire-based ultraviolet photodetectors aligned by a non-uniform electric field

    Science.gov (United States)

    Park, Hyunik; Yang, Gwangseok; Chun, Seungju; Kim, Donghwan; Kim, Jihyun

    2013-07-01

    We report on ultraviolet (UV) photodetectors fabricated by positioning Cadmium Telluride (CdTe) microwires (μWs) precisely by dielectrophoretic (DEP) force, where CdTe μWs were grown using an Au-catalyst-assisted closed-space-sublimation (CSS) method. The optical properties of CSS-grown CdTe μWs were characterized by micro-photoluminescence and micro-Raman spectroscopies. Optoelectronic characteristics were obtained after CdTe μWs were aligned on a pre-patterned SiO2/Si substrate by a non-uniform electric field. Photocurrents were increased with increasing the light intensities. Fast and reliable photoresponse and recovery were observed when CdTe μWs were exposed to UV illuminations. We demonstrated that high quality CdTe μWs grown by the CSS method have significant potentials as optoelectronic devices.

  7. First-principles study of roles of Cu and Cl in polycrystalline CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ji-Hui; Park, Ji-Sang; Metzger, Wyatt [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Yin, Wan-Jian [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); College of Physics, Optoelectronics and Energy and Collaborative, Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Wei, Su-Huai, E-mail: suhuaiwei@csrc.ac.cn [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Beijing Computational Science Research Center, Beijing 100094 (China)

    2016-01-28

    Cu and Cl treatments are important processes to achieve high efficiency polycrystalline cadmium telluride (CdTe) solar cells, thus it will be beneficial to understand the roles they play in both bulk CdTe and CdTe grain boundaries (GBs). Using first-principles calculations, we systematically study Cu and Cl-related defects in bulk CdTe. We find that Cl has only a limited effect on improving p-type doping and too much Cl can induce deep traps in bulk CdTe, whereas Cu can enhance p-type doping of bulk CdTe. In the presence of GBs, we find that, in general, Cl and Cu will prefer to stay at GBs, especially for those with Te-Te wrong bonds, in agreement with experimental observations.

  8. Measuring long-range carrier diffusion across multiple grains in polycrystalline semiconductors by photoluminescence imaging

    Science.gov (United States)

    Alberi, K.; Fluegel, B.; Moutinho, H.; Dhere, R. G.; Li, J. V.; Mascarenhas, A.

    2013-10-01

    Thin-film polycrystalline semiconductors are currently at the forefront of inexpensive large-area solar cell and integrated circuit technologies because of their reduced processing and substrate selection constraints. Understanding the extent to which structural and electronic defects influence carrier transport in these materials is critical to controlling the optoelectronic properties, yet many measurement techniques are only capable of indirectly probing their effects. Here we apply a novel photoluminescence imaging technique to directly observe the low temperature diffusion of photocarriers through and across defect states in polycrystalline CdTe thin films. Our measurements show that an inhomogeneous distribution of localized defect states mediates long-range hole transport across multiple grain boundaries to locations exceeding 10 μm from the point of photogeneration. These results provide new insight into the key role deep trap states have in low temperature carrier transport in polycrystalline CdTe by revealing their propensity to act as networks for hopping conduction.

  9. Measuring long-range carrier diffusion across multiple grains in polycrystalline semiconductors by photoluminescence imaging.

    Science.gov (United States)

    Alberi, K; Fluegel, B; Moutinho, H; Dhere, R G; Li, J V; Mascarenhas, A

    2013-01-01

    Thin-film polycrystalline semiconductors are currently at the forefront of inexpensive large-area solar cell and integrated circuit technologies because of their reduced processing and substrate selection constraints. Understanding the extent to which structural and electronic defects influence carrier transport in these materials is critical to controlling the optoelectronic properties, yet many measurement techniques are only capable of indirectly probing their effects. Here we apply a novel photoluminescence imaging technique to directly observe the low temperature diffusion of photocarriers through and across defect states in polycrystalline CdTe thin films. Our measurements show that an inhomogeneous distribution of localized defect states mediates long-range hole transport across multiple grain boundaries to locations exceeding 10 μm from the point of photogeneration. These results provide new insight into the key role deep trap states have in low temperature carrier transport in polycrystalline CdTe by revealing their propensity to act as networks for hopping conduction.

  10. Responsivity Calibration of Pyroelectric Terahertz Detectors

    CERN Document Server

    Berry, Christopher W; Jarrahi, Mona

    2014-01-01

    There has been a significant advancement in terahertz radiation sources in the past decade, making milliwatt terahertz power levels accessible in both continuous-wave and pulsed operation. Such high-power terahertz radiation sources circumvent the need for cryogenic-cooled terahertz detectors such as semiconductor bolometers and necessitate the need for new types of calibrated, room-temperature terahertz detectors. Among various types of room-temperature terahertz detectors, pyroelectric detectors are one of the most widely used detectors, which can offer wide dynamic range, broad detection bandwidth, and high sensitivity levels. In this article, we describe the calibration process of a commercially available pyroelectric detector (Spectrum Detector, Inc, SPI-A-65 THz), which incorporates a 5 mm diameter LiTaO3 detector with an organic terahertz absorber coating.

  11. Probabilistic electron density distribution in CdTe at RT and 200K

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, R. [Department of Physics, The Madura College, Madurai - 625 011, Tamil Nadu (India); Israel, S. [Department of Physics, American College, Madurai - 625 002, Tamil Nadu (India); Ono, Y.; Kajitani, T. [Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Ohno, K. [Institute for Materials Research, Tohoku University, Sendai, 980-8577 (Japan); Isshiki, M. [Institute for Advanced Materials Processing, Tohoku University, Sendai, 980-8577 (Japan); Rajaram, R.K. [School of Physics, Madurai Kamaraj University, Madurai - 625 021, Tamil Nadu (India)

    2006-03-15

    The bonding between the atoms in the II-VI compound semiconductors has always been a subject of rigorous research because of their tremendous applications in a variety of fields. The bonding and ionic character in CdTe at 300 and 200 K have been determined quantitatively as well as qualitatively using single crystal X-ray data sets and MEM (Maximum Entropy Method) as the tool for the reconstruction of the electron densities distributed within the unit cell. The ab-initio band calculation of the total and valence charge densities have been carried out theoretically by means of the local density approximation (LDA) method in support of the experimentally derived MEM maps. The difference density maps show fewer errors between the theoretical and experimental charge density and thus gives credence to the results accordingly. Along the bonding direction [111], the mid-bond electron densities are found to be 0.233 e/Aa{sup 3} and 0.284 e/Aa{sup 3} at 300 K and 200 K at distances 1.4026 Aa and 1.4036 Aa respectively. The densities along [100] and [110] show an increase in the charge concentration at the bond at lower temperatures. copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim. (orig.)

  12. Atomic and electronic structure of Lomer dislocations at CdTe bicrystal interface.

    Science.gov (United States)

    Sun, Ce; Paulauskas, Tadas; Sen, Fatih G; Lian, Guoda; Wang, Jinguo; Buurma, Christopher; Chan, Maria K Y; Klie, Robert F; Kim, Moon J

    2016-06-03

    Extended defects are of considerable importance in determining the electronic properties of semiconductors, especially in photovoltaics (PVs), due to their effects on electron-hole recombination. We employ model systems to study the effects of dislocations in CdTe by constructing grain boundaries using wafer bonding. Atomic-resolution scanning transmission electron microscopy (STEM) of a [1-10]/(110) 4.8° tilt grain boundary reveals that the interface is composed of three distinct types of Lomer dislocations. Geometrical phase analysis is used to map strain fields, while STEM and density functional theory (DFT) modeling determine the atomic structure at the interface. The electronic structure of the dislocation cores calculated using DFT shows significant mid-gap states and different charge-channeling tendencies. Cl-doping is shown to reduce the midgap states, while maintaining the charge separation effects. This report offers novel avenues for exploring grain boundary effects in CdTe-based solar cells by fabricating controlled bicrystal interfaces and systematic atomic-scale analysis.

  13. Growth and characterization of CdTe and CdZnTe crystals for substrate application

    Science.gov (United States)

    Azoulay, Moshe; Zilber, Raphael; Shusterman, Sergy; Goldgirsh, Alex; Zontag, Itzhak

    2003-01-01

    During the last decade we have investigated the synthesis, growth and characterization of CdTe and CdZnTe semiconductor compounds. As a result, substrate crystals, suitable for mercury cadmium telluride thin film growth are prepared. The emphasis will be given to the investigation of the thermal regime during growth, reflected at the solid liquid interface shape and its influence on the crystalline quality. Seeded and unseeded growth experiments are compared in terms of structural crystalline quality. Seeded and unseeded growth experiments are compared in terms of structural crystalline perfection as well as single crystal yield. The effect of thermal annealing on IR transmittance, precipitates and inclusions will be discussed in detail. Moreover, we will show the recent new trends for simulation of crystal growth processes by CRYSVUN software as well as practical implementation of calculated data for the grwoth of II-VI crystals. Preliminary study on the vapor phase control during growth and crystal cooling procedures will also be discussed.

  14. Radiation tolerant compact image sensor using CdTe photodiode and field emitter array (Conference Presentation)

    Science.gov (United States)

    Masuzawa, Tomoaki; Neo, Yoichiro; Mimura, Hidenori; Okamoto, Tamotsu; Nagao, Masayoshi; Akiyoshi, Masafumi; Sato, Nobuhiro; Takagi, Ikuji; Tsuji, Hiroshi; Gotoh, Yasuhito

    2016-10-01

    A growing demand on incident detection is recognized since the Great East Japan Earthquake and successive accidents in Fukushima nuclear power plant in 2011. Radiation tolerant image sensors are powerful tools to collect crucial information at initial stages of such incidents. However, semiconductor based image sensors such as CMOS and CCD have limited tolerance to radiation exposure. Image sensors used in nuclear facilities are conventional vacuum tubes using thermal cathodes, which have large size and high power consumption. In this study, we propose a compact image sensor composed of a CdTe-based photodiode and a matrix-driven Spindt-type electron beam source called field emitter array (FEA). A basic principle of FEA-based image sensors is similar to conventional Vidicon type camera tubes, but its electron source is replaced from a thermal cathode to FEA. The use of a field emitter as an electron source should enable significant size reduction while maintaining high radiation tolerance. Current researches on radiation tolerant FEAs and development of CdTe based photoconductive films will be presented.

  15. Luminescence effects of ion-beam bombardment of CdTe surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Olvera, J., E-mail: javier.olvera@uam.e [Laboratorio de Crecimiento de Cristales, Dpto. de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Martinez, O. [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011 Valladolid (Spain); Plaza, J.L.; Dieguez, E. [Laboratorio de Crecimiento de Cristales, Dpto. de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2009-09-15

    In the present work, we report the effect of low-energy ion bombardment on CdTe surfaces. The effect is revealed by FESEM images and photoluminescence (PL) measurements carried out before and after irradiation of CdTe polycrystals by means of an ion-beam sputtering (IBS) system. An important improvement in the luminescence of CdTe was observed in the irradiated areas, related to defect-free surfaces.

  16. Applicability of a portable CdTe and NaI (Tl) spectrometer for activity measure; Aplicabilidade de um espectrometro portatil de CdTe e NaI (Tl) para a medida da atividade de Cesio-137 ({sup 137}Cs) e Berilio-7 ({sup 7}Be)

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Jaquiel Salvi

    2005-02-15

    In this work it was studied the application of an in situ gamma spectrometer (ROVER) of Amptek Inc., composed by a Cadmium Telluride detector (CdTe) of 3 mm x 3 mm x 1 mm and a 30 mm x 30 mm Sodium Iodide detector doped with Thallium [NaI (Tl)). The radioactive sources used were type pastille, sealed in aluminum and polyethylene, of {sup 241}Am, {sup 133}Ba, {sup 152}Eu, 3 sources of {sup 137}Cs and soil samples contaminated with {sup 137}Cs. It was performed a factorial planning 2{sup 3} to optimize the in situ spectrometry system. This way it was determined that the best temperature for CdTe crystal operation is -22, deg C, with Shaping Time of 3 {mu}S and Rise Time Discrimination (RTD) with value 3. With the help of the certified radioactive sources, we determined the efficiency curve of the two detectors. The CdTe detector was positioned at the standard distance of 1 meter of the sources and also at 4.15 cm. The NaI (Tl) detector was also positioned at the standard distance of 1 meter of the sources and at 2.8 cm. Measures were performed to determine the Minimum Detectable Activity (MDA) for both detectors. For the pastille type sources, the {sup 137}Cs MDA for the CdTe detector at 4.15 cm, analyzing the energy line of 32 keV, was 6 kBq and at 1 meter of the {sup 137}Cs source, analyzing the line of 661.65 keV, the MDA was 67 kBq. For soil samples, CdTe detector at 4.15 cm presented a MDA of 693 kBq.kg-l for the line of 32 keV, and for the soil sample {sup 7}Be content the MDA found was 2867 Bq.kg{sup -1} at 4.15 cm. For the NaI (Tl) detector, analyzing the line of 661.65 keV, the {sup 137}Cs MDA for pastille type source at 1 meter of distance was 7 kBq, and for soil sample at 2.8 cm the measured {sup 137}Cs MDA was 71 Bq.kg{sup -1}. For the soil sample {sup 7}Be content, at 2.8 cm of the Nal (Tl) detector, the obtained MDA was 91 Bq.kg{sup -1}. Due to the minimum detectable activities found for the two detectors, we concluded that the employed in situ gamma

  17. Quantum processes in semiconductors

    CERN Document Server

    Ridley, B K

    2013-01-01

    Aimed at graduate students, this is a guide to quantum processes of importance in the physics and technology of semiconductors. The fifth edition includes new chapters that expand the coverage of semiconductor physics relevant to its accompanying technology.

  18. The ATLAS semiconductor tracker (SCT)

    CERN Document Server

    Jackson, J N

    2005-01-01

    The ATLAS detector (CERN/LHCC/94-43 (1994)) is designed to study a wide range of physics at the CERN Large Hadron Collider (LHC) at luminosities up to 10**3**4 cm**-**2 s**-**1 with a bunch-crossing rate of 40 MHz. The Semiconductor Tracker (SCT) forms a key component of the Inner Detector (vol. 1, ATLAS TDR 4, CERN/LHCC 97-16 (1997); vol. 2, ATLAS TDR 5, CERN/LHCC 97-17 (1997)) which is situated inside a 2 T solenoid field. The ATLAS Semiconductor Tracker (SCT) utilises 4088 silicon modules with binary readout mounted on carbon fibre composite structures arranged in the forms of barrels in the central region and discs in the forward region. The construction of the SCT is now well advanced. The design of the SCT modules, services and support structures will be briefly outlined. A description of the various stages in the construction process will be presented with examples of the performance achieved and the main difficulties encountered. Finally, the current status of the construction is reviewed.

  19. CdTe polycrystalline films on Ni foil substrates by screen printing and their photoelectric performance

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Huizhen [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Ma, Jinwen [College of New Energy, Bohai University, Jinzhou, Liaoning 121013 (China); Mu, Yannan [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Department of Physics and Chemistry, Heihe University, Heihe 164300 (China); Su, Shi; Lv, Pin; Zhang, Xiaoling; Zhou, Liying; Li, Xue; Liu, Li; Fu, Wuyou [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Yang, Haibin, E-mail: yanghb@jlu.edu.cn [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China)

    2015-06-15

    Highlights: • The sintered CdTe polycrystalline films by a simple screen printing. • The flexible Ni foil was chose as substrates to reduce the weight of the electrode. • The compact CdTe film was obtained at 550 °C sintering temperature. • The photoelectric activity of the CdTe polycrystalline films was excellent. - Abstract: CdTe polycrystalline films were prepared on flexible Ni foil substrates by sequential screen printing and sintering in a nitrogen atmosphere for the first time. The effect of temperature on the quality of the screen-printed film was investigated in our work. The high-quality CdTe films were obtained after sintering at 550 °C for 2 h. The properties of the sintered CdTe films were characterized by scanning electron microscopy, X-ray diffraction pattern and UV–visible spectroscopy. The high-quality CdTe films have the photocurrent was 2.04 mA/cm{sup 2}, which is higher than that of samples prepared at other temperatures. Furthermore, CdCl{sub 2} treatment reduced the band gap of the CdTe film due to the larger grain size. The photocurrent of photoelectrode based on high crystalline CdTe polycrystalline films after CdCl{sub 2} treatment improved to 2.97 mA/cm{sup 2}, indicating a potential application in photovoltaic devices.

  20. Photoluminescence and Electroluminescence Properties of CdTe Nanoparticles in Conjugated Polymer Hosts

    Institute of Scientific and Technical Information of China (English)

    GUO, Fengqi; XIE, Puhui

    2009-01-01

    The photoinduced energy transfer process from conjugated polymer (PPE4+) to CdTe nanocrystals was found both in solutions and in thin films by a fluorescence spectroscopic technique. Films of PPE4+ blended with CdTe-2 nanocrystals were formed by an electrostatic layer-by-layer assembly technique. Light emitting diodes were fabricated using CdTe-2 as an emitter in PPE4+ host. PPE4+ works as a molecular wire in the energy transfer process from the polymer to the CdTe-2 nanocrystals.

  1. Review of Photovoltaic Energy Production Using CdTe Thin-Film Modules: Extended Abstract Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gessert, T. A.

    2008-09-01

    CdTe has near-optimum bandgap, excellent deposition traits, and leads other technologies in commercial PV module production volume. Better understanding materials properties will accelerate deployment.

  2. Effects of CdTe growth conditions and techniques on the efficiency limiting defects and mechanisms in CdTe solar cells

    Science.gov (United States)

    Rohatgi, A.; Chou, H. C.; Jokerst, N. M.; Thomas, E. W.; Ferekides, C.; Kamra, S.; Feng, Z. C.; Dugan, K. M.

    1996-01-01

    CdTe solar cells were fabricated by depositing CdTe films on CdS/SnO2/glass substrates using close-spaced sublimation (CSS) and metalorganic chemical vapor deposition (MOCVD). Te/Cd mole ratio was varied in the range of 0.02 to 6 in the MOCVD growth ambient in an attempt to vary the native defect concentration. Polycrystalline CdTe layers grown by MOCVD and CSS both showed average grain size of about 2 μm. However, the CdTe films grown by CSS were found to be less faceted and more dense compared to the CdTe grown by MOCVD. CdTe growth techniques and conditions had a significant impact on the electrical characteristics of the cells. The CdTe solar cells grown by MOCVD in the Te-rich growth condition and by the CSS technique gave high cell efficiencies of 11.5% and 12.4%, respectively, compared to 6.6% efficient MOCVD cells grown in Cd-rich conditions. This large difference in efficiency is explained on the basis of (a) XRD measurements which showed a higher degree of atomic interdiffusion at the CdS/CdTe interface in high performance devices, (b) Raman measurements which endorsed more uniform and preferred grain orientation by revealing a sharp CdTe TO mode in the high efficiency cells, and (c) carrier transport mechanism which switched from tunneling/interface recombination to depletion region recombination in the high efficiency cells. In this study, Cu/Au layers were evaporated on CdTe for the back contact. Lower efficiency of the Te-rich MOCVD cells, compared to the CSS cells, was attributed to contact related additional loss mechanisms, such as Cd pile-up near Cu/CdTe interface which can give rise to Cd-vacancy defects in the bulk, and higher Cu concentration in the CdTe layer which can cause shunts in the device. Finally, SIMS measurements on the CdTe films of different crystallinity and grain size confirmed that grain boundaries are the main conduits for Cu migration into the CdTe film. Thus larger CdTe grain size or lower grain boundary area per unit volume

  3. 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.

  4. Magneto-optical Faraday rotation of semiconductor nanoparticles embedded in dielectric matrices.

    Science.gov (United States)

    Savchuk, Andriy I; Stolyarchuk, Ihor D; Makoviy, Vitaliy V; Savchuk, Oleksandr A

    2014-04-01

    Faraday rotation has been studied for CdS, CdTe, and CdS:Mn semiconductor nanoparticles synthesized by colloidal chemistry methods. Additionally these materials were prepared in a form of semiconductor nanoparticles embedded in polyvinyl alcohol films. Transmission electron microscopy and atomic force microscopy analyses served as confirmation of nanocrystallinity and estimation of the average size of the nanoparticles. Spectral dependence of the Faraday rotation for the studied nanocrystals and nanocomposites is correlated with a blueshift of the absorption edge due to the confinement effect in zero-dimensional structures. Faraday rotation spectra and their temperature behavior in Mn-doped nanocrystals demonstrates peculiarities, which are associated with s, p-d exchange interaction between Mn²⁺ ions and band carriers in diluted magnetic semiconductor nanostructures.

  5. Phosphorus Doping of Polycrystalline CdTe by Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Colegrove, Eric; Albin, David S.; Guthrey, Harvey; Harvey, Steve; Burst, James; Moutinho, Helio; Farrell, Stuart; Al-Jassim, Mowafak; Metzger, Wyatt K.

    2015-06-14

    Phosphorus diffusion in single crystal and polycrystalline CdTe material is explored using various methods. Dynamic secondary ion mass spectroscopy (SIMS) is used to determine 1D P diffusion profiles. A 2D diffusion model is used to determine the expected cross-sectional distribution of P in CdTe after diffusion anneals. Time of flight SIMS and cross-sectional cathodoluminescence corroborates expected P distributions. Devices fabricated with diffused P exhibit hole concentrations up to low 1015 cm-3, however a subsequent activation anneal enabled hole concentrations greater than 1016 cm-3. CdCl2 treatments and Cu based contacts were also explored in conjunction with the P doping process.

  6. Dependence of CdTe response of bias history

    Energy Technology Data Exchange (ETDEWEB)

    Sites, J.R.; Sasala, R.A.; Eisgruber, I.L. [Colorado State Univ., Boulder, CO (United States)

    1995-11-01

    Several time-dependent effect have been observed in CdTe cells and modules in recent years. Some appear to be related to degradation at the back contact, some to changes in temperature at the thin-film junction, and some to the bias history of the cell or module. Back-contact difficulties only occur in some cases, and the other two effects are reversible. Nevertheless, confusion in data interpretation can arise when these effects are not characterized. This confusion can be particularly acute when more than one time-dependent effect occurs during the same measurement cycle. The purpose of this presentation is to help categorize time-dependent effects in CdTe and other thin-film cells to elucidate those related to bias history, and to note differences between cell and module analysis.

  7. Photoluminescence study of Cu diffusion in CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Grecu, D.; Compaan, A.D. [Department of Physics, University of Toledo, Toledo, Ohio (United States)

    1999-03-01

    We report changes in the photoluminescence spectra associated with the diffusion of Cu in CdTe thin films used in CdTe/CdS solar cells. Films grown by vapor transport deposition and radio-frequency sputtering as well as single crystal CdTe were included in the study. The main effects of Cu diffusion appear to be the quenching of a donor-acceptor transition associated with Cd vacancies and the increase in intensity of a lower energy broad-band transition. The PL is subsequently used to explore the effects of electric fields on Cu diffusion. The role of Te as a diffusion barrier for Cu is investigated. {copyright} {ital 1999 American Institute of Physics.}

  8. Optical properties of CdTe: Experiment and modeling

    Science.gov (United States)

    Adachi, Sadao; Kimura, Toshifumi; Suzuki, Norihiro

    1993-09-01

    The real epsilon(sub 1) and imaginary epsilon(sub 2) portions of the dielectric function of CdTe were measured by spectroscopic ellipsometry (SE) in the 1.1-5.6 eV photon-energy range at room temperature. The data obtained were analyzed using different theoretical models, namely the harmonic-oscillator approximation, the standard critical point, and the model dielectric function. These models include the E(sub 0), E(sub 0) + Delta(sub 0), E(sub 1), E(sub 1) + Delta(sub 1), and E(sub 2) gaps as the main dispersion mechanisms. The consequences were reported and of particular interest was the difference in the analyzed results between these theoretical models. Dielectric-related optical constants of CdTe, such as the complex refractive index, the absorption coefficient, and normal-incidence reflectivity, were also investigated.

  9. Stepwise cooling technique as a method of growing high-perfection Cl-compensated CdTe

    Science.gov (United States)

    Pavlyuk, M. D.; Subbotin, I. A.; Kanevsky, V. M.; Artemov, V. V.

    2017-01-01

    High-perfection crystals of Cl-compensated CdTe have been grown by the Obreimov-Shubnikov technique using a schedule of stepwise crystal cooling developed with due regard for the correct CdTe phase diagram.

  10. CdTe Nanowires studied by Transient Absorption Microscopy

    Directory of Open Access Journals (Sweden)

    Kuno M.

    2013-03-01

    Full Text Available Transient absorption measurements were performed on single CdTe nanowires. The traces show fast decays that were assigned to charge carrier trapping at surface states. The observed power dependence suggests the existence of a trap-filling mechanism. Acoustic phonon modes were also observed, which were assigned to breathing modes of the nanowires. Both the fundamental breathing mode and the first overtone were observed, and the dephasing times provide information about how the nanowires interact with their environment.

  11. Optical modeling of graphene contacted CdTe solar cells

    Science.gov (United States)

    Aldosari, Marouf; Sohrabpoor, Hamed; Gorji, Nima E.

    2016-04-01

    For the first time, an optical model is applied on CdS/CdTe thin film solar cells with graphene front or back contact. Graphene is highly conductive and is as thin as a single atom which reduces the light reflection and absorption, and thus enhances the light transmission to CdTe layer for a wide range of wavelengths including IR. Graphene as front electrode of CdTe devices led to loss in short circuit current density of 10% ΔJsc ≤ 15% compared to the conventional electrodes of TCO and ITO at CdS thickness of dCdS = 100 nm. In addition, all the multilayer graphene electrodes with 2, 4, and 7 graphene layers led to Jsc ≤ 20 mA/cm2. Therefore, we conclude that a single monolayer graphene with hexagonal carbon network reduces optical losses and enhances the carrier collection measured as Jsc. In another structure design, we applied the optical model to graphene back contacted CdS/CdTe device. This scheme allows double side irradiation of the cell which is expected to enhance the Jsc. We obtained 1 ∼ 6 , 23, and 38 mA/cm2 for back, front and bifacial illumination of graphene contacted CdTe cell with CdS = 100 nm. The bifacial irradiated cell, to be efficient, requires an ultrathin CdTe film with dCdTe ≤ 1 μm. In this case, the junction electric field extends to the back region and collects out the generated carriers efficiently. This was modelled by absorptivity rather than transmission rate and optical losses. Since the literature suggest that ZnO can increase the graphene conductivity and enhance the Jsc, we performed our simulations for a graphene/ZnO electrode (ZnO = 100 nm) instead of a single graphene layer.

  12. Photoreactions on (110) compound semiconductor surfaces

    Science.gov (United States)

    Lasky, Peter John

    Photo-initiated and thermal reactions of alkyl halides and dimethyl metals on (110) GaAs and CdTe surfaces have been studied under Ultra High Vacuum (UHV) conditions. These specific systems have been chosen because they allow investigation of mechanisms underlying reactions relevant to semiconductor processing. Thermal reactivity studies, binding energy measurements, coverage calibrations, and analyses of photoreaction products have been made using Temperature Programmed Desorption (TPD). The dynamics of photoreactions, induced by irradiation from excimer and excimer-pumped dye lasers, have been investigated using Time of Flight (TOF) methods with a quadrupole mass spectrometer. On these (110) semiconductor surfaces, methyl halides, CH3X (X = Cl, Br, I), exhibit molecular adsorption and desorption at [Adsorption Fine Structure (NEXAFS) measurements and corroborated by ab initio calculations done in collaboration with Professor Friesner's group. TOF studies indicate that, in the first monolayer, dissociation proceeds via creation of hot electrons in the substrate and transfer to adsorbate molecules resulting in a process analogous to Dissociative Electron Attachment (DEA) seen in the gas phase. The initial excitation energy necessary to induce this hot electron chemistry with CH3Br on GaAs(110) has been accurately determined and is below that needed for photoemission. With multilayer coverages, direct photolysis is observed; however, it is quenched in the first monolayer. Similar effects are observed in other alkyl halides. (CH3)2M, M = Cd, Zn adsorb molecularly on GaAs(110) at 80 K, but upon heating dissociate before desorbing. Depending upon the initial coverage, (CH3)3Ga,/ (CH3)2M, M, and As2 are observed in TPD due to methyl transfer from the adsorbate to the surface Ga species. Methyl transfer reactions are also seen when (CH3)3Ga is adsorbed directly on this surface. On CdTe(110), (CH3)2Cd adsorbs and desorbs molecularly intact. Upon irradiation at 80 K, no

  13. Unitary lens semiconductor device

    Science.gov (United States)

    Lear, Kevin L.

    1997-01-01

    A unitary lens semiconductor device and method. The unitary lens semiconductor device is provided with at least one semiconductor layer having a composition varying in the growth direction for unitarily forming one or more lenses in the semiconductor layer. Unitary lens semiconductor devices may be formed as light-processing devices such as microlenses, and as light-active devices such as light-emitting diodes, photodetectors, resonant-cavity light-emitting diodes, vertical-cavity surface-emitting lasers, and resonant cavity photodetectors.

  14. High efficiency CSS CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ferekides, C.S.; Marinskiy, D.; Viswanathan, V.; Tetali, B.; Palekis, V.; Selvaraj, P.; Morel, D.L. [University of South Florida, Tampa, FL (United States). Dept. of Electrical Engineering

    2000-02-21

    Cadmium telluride (CdTe) has long been recognized as a strong candidate for thin film solar cell applications. It has a bandgap of 1.45 eV, which is nearly ideal for photovoltaic energy conversion. Due to its high optical absorption coefficient essentially all incident radiation with energy above its band-gap is absorbed within 1-2 {mu}m from the surface. Thin film CdTe solar cells are typically heterojunctions, with cadmium sulfide (CdS) being the n-type junction partner. Small area efficiencies have reached the 16.0% level and considerable efforts are underway to commercialize this technology. This paper will present work carried out at the University South Florida sponsored by the National Renewable Energy Laboratory of the United States Department of Energy, on CdTe/CdS solar cells fabricated using the close spaced sublimation (CSS) process. The CSS technology has attractive features for large area applications such as high deposition rates and efficient material utilization. The structural and optical properties of CSS CdTe and CdS films and junctions will be presented and the influence of some important CSS process parameters will be discussed. (orig.)

  15. New materials for radiation hard semiconductor dectectors

    Science.gov (United States)

    Sellin, P. J.; Vaitkus, J.

    2006-02-01

    We present a review of the current status of research into new semiconductor materials for use as particle tracking detectors in very high radiation environments. This work is carried out within the framework of the CERN RD50 collaboration, which is investigating detector technologies suitable for operation at the proposed super-LHC facility (SLHC). Tracking detectors operating at the SLHC in this environment will have to be capable of withstanding radiation levels arising from a luminosity of 10 35 cm -2 s -1 which will present severe challenges to current tracking detector technologies. The "new materials" activity within RD50 is investigating the performance of various semiconductor materials that potentially offer radiation hard alternatives to silicon devices. The main contenders in this study are silicon carbide, gallium nitride and amorphous silicon. In this paper we review the current status of these materials, in terms of material quality, commercial availability, charge transport properties, and radiation hardness studies. Whilst these materials currently show considerable promise for use as radiation hard tracking detectors, their ultimate success will depend on the continued improvement of the availability of high quality material.

  16. Approaches to improve the Voc of CDTE devices: Device modeling and thinner devices, alternative back contacts

    Science.gov (United States)

    Walkons, Curtis J.

    An existing commercial process to develop thin film CdTe superstrate cells with a lifetime tau=1-3 ns results in Voc= 810-850 mV which is 350 mV lower than expected for CdTe with a bandgap EG = 1.5 eV. Voc is limited by 1.) SRH recombination in the space charge region; and 2.) the Cu2Te back contact to CdTe, which, assuming a 0.3 eV CdTe/Cu2Te barrier, exhibits a work function of phi Cu2Te= 5.5 eV compared to the CdTe valence band of Ev,CdTe=5.8 eV. Proposed solutions to develop CdTe devices with increased Voc are: 1.) reduce SRH recombination by thinning the CdTe layer to ≤ 1 mum; and 2.) develop an ohmic contact back contact using a material with phi BC≥5.8 eV. This is consistent with simulations using 1DSCAPS modeling of CdTe/CdS superstrate cells under AM 1.5 conditions. Two types of CdTe devices are presented. The first type of CdTe device utilizes a window/CdTe stack device with an initial 3-9 mum CdTe layer which is then chemically thinned resulting in regions of the CdTe film with thickness less than 1 mum. The CdTe surface was contacted with a liquid junction quinhydrone-Pt (QH-Pt) probe which enables rapid repeatable Voc measurements on CdTe before and after thinning. In four separate experiments, the window/CdTe stack devices with thinned CdTe exhibited a Voc increase of 30-170 mV, which if implemented using a solid state contact could cut the Voc deficit in half. The second type of CdTe device utilizes C61 PCBM as a back contact to the CdTe, selected since PCBM has a valence band maximum energy (VBM) of 5.8 eV. The PCBM films were grown by two different chemistries and the characterization of the film properties and device results are discussed. The device results show that PCBM exhibits a blocking contact with a 0.6 eV Schottky barrier and possible work function of phiPCBM = 5.2 eV.

  17. Single-Crystal CdTe Homojunction Structures for Solar Cell Applications

    Science.gov (United States)

    Su, Peng-Yu; Dahal, Rajendra; Wang, Gwo-Ching; Zhang, Shengbai; Lu, Toh-Ming; Bhat, Ishwara B.

    2015-09-01

    We report two different CdTe homojunction solar cell structures. Single-crystal CdTe homojunction solar cells were grown on GaAs single-crystal substrates by metalorganic chemical vapor deposition. Arsenic and iodine were used as dopants for p-type and n-type CdTe, respectively. Another homojunction solar cell structure was fabricated by growing n-type CdTe directly on bulk p-type CdTe single-crystal substrates. The electrical properties of the different layers were characterized by Hall measurements. When arsine was used as arsenic source, the highest hole concentration was ~6 × 1016 cm-3 and the activation efficiency was ~3%. Very abrupt arsenic doping profiles were observed by secondary ion mass spectrometry. For n-type CdTe with a growth temperature of 250°C and a high Cd/Te ratio the electron concentration was ~4.5 × 1016 cm-3. Because of the 300 nm thick n-type CdTe layer, the short circuit current of the solar cell grown on the bulk CdTe substrate was less than 10 mA/cm2. The open circuit voltage of the device was 0.86 V. According to a prediction based on measurement of short circuit current density ( J sc) as a function of open circuit voltage ( V oc), an open circuit voltage of 0.92 V could be achieved by growing CdTe solar cells on bulk CdTe substrates.

  18. Sensitivity of a new-developed neutron detector

    Institute of Scientific and Technical Information of China (English)

    PENG Tai-Ping; ZHU Xue-Bin; YANG Hong-Qiong; YANG Jian-Lun; YANG Gao-Zhao; LI Lin-Bo; SONG Xian-Cai

    2005-01-01

    We develop a kind of neutron detector, which consists of a polyethylene thin film and two PIN semiconductors connected face-to-face. The detector is insensitive to γ-rays. Its sensitivity to neutron has been calculated with MCNP program and calibrated by experiments, and the results indicate that the neutron sensitivity of the compensation detector will vary with polyethylene converter. The compensation PIN detector can be employed to measure pulse neutron in neutron and gamma mixture radiation field.

  19. AlN Based Extreme Ultraviolet (EUV) Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I project is to investigate the feasibility for achieving EUV detectors for space applications by exploiting the ultrahigh bandgap semiconductor - AlN. We...

  20. Crystallization of II-VI semiconductor compounds forming long microcrystalline linear assemblies

    Directory of Open Access Journals (Sweden)

    Marcelino Becerril

    2013-04-01

    Full Text Available In this work we report the formation of long microcrystalline linear self-assemblies observed during the thin film growth of several II-VI compounds. Polycrystalline CdTe, CdS, CdCO3, and nanocrystalline CdTe:Al thin films were prepared on glass substrates by different deposition techniques. In order to observe these crystalline formations in the polycrystalline materials, the thin film growth was suspended before the grains reached to form a continuous layer. The chains of semiconductor crystals were observed among many isolated and randomly distributed grains. Since CdTe, CdTe:Al, CdS and CdCO3 are not ferroelectric and/or ferromagnetic materials, the relevant problem would be to explain what is the mechanism through which the grains are held together to form linear chains. It is well known that some nanocrystalline materials form rods and wires by means of electrostatic forces. This occurs in polar semiconductors, where it is assumed that the attraction forces between surface polar faces of the small crystals are the responsible for the chains formation. Since there are not too many mechanisms responsible for the attraction we assume that a dipolar interaction is the force that originates the formation of chain-like grain clusters. The study of this property can be useful for the understanding of nucleation processes in the growth of semiconductor thin films.

  1. Analysis of the electrodeposition and surface chemistry of CdTe, CdSe, and CdS thin films through substrate-overlayer surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Gu, Junsi; Fahrenkrug, Eli; Maldonado, Stephen

    2014-09-02

    The substrate-overlayer approach has been used to acquire surface enhanced Raman spectra (SERS) during and after electrochemical atomic layer deposition (ECALD) of CdSe, CdTe, and CdS thin films. The collected data suggest that SERS measurements performed with off-resonance (i.e. far from the surface plasmonic wavelength of the underlying SERS substrate) laser excitation do not introduce perturbations to the ECALD processes. Spectra acquired in this way afford rapid insight on the quality of the semiconductor film during the course of an ECALD process. For example, SERS data are used to highlight ECALD conditions that yield crystalline CdSe and CdS films. In contrast, SERS measurements with short wavelength laser excitation show evidence of photoelectrochemical effects that were not germane to the intended ECALD process. Using the semiconductor films prepared by ECALD, the substrate-overlayer SERS approach also affords analysis of semiconductor surface adsorbates. Specifically, Raman spectra of benzenethiol adsorbed onto CdSe, CdTe, and CdS films are detailed. Spectral shifts in the vibronic features of adsorbate bonding suggest subtle differences in substrate-adsorbate interactions, highlighting the sensitivity of this methodology.

  2. Energy transfer processes in semiconductor quantum dots: bacteriorhodopsin hybrid system

    Science.gov (United States)

    Rakovich, Aliaksandra; Sukhanova, Alyona; Bouchonville, Nicolas; Molinari, Michael; Troyon, Michel; Cohen, Jacques H. M.; Rakovich, Yury; Donegan, John F.; Nabiev, Igor

    2009-05-01

    The potential impact of nanoscience on energy transfer processes in biomolecules was investigated on the example of a complex between fluorescent semiconductor nanocrystals and photochromic membrane protein. The interactions between colloidal CdTe quantum dots (QDs) and bacteriorhodopsin (bR) protein were studied by a variety of spectroscopic techniques, including integrated and time-resolved fluorescence spectroscopies, zeta potential and size measurement, and fluorescence correlation spectroscopy. QDs' luminescence was found to be strongly modulated by bacteriorhodopsin, but in a controllable way. Decreasing emission lifetimes and blue shifts in QDs' emission at increasing protein concentrations suggest that quenching occurs via Förster resonance energy transfer. On the other hand, concave Stern-Volmer plots and sigmoidal photoluminescence quenching curves imply that the self-assembling of NCs and bR exists, and the number of nanocrystals (NCs) per bacteriorhodopsin contributing to energy transfer can be determined from the inflection points of sigmoidal curves. This number was found to be highly dependent not only on the spectral overlap between NC emission and bR absorption bands, but also on nanocrystal surface charge. These results demonstrate the potential of how inorganic nanoscale materials can be employed to improve the generic molecular functions of biomolecules. The observed interactions between CdTe nanocrystals and bacteriorhodopsin can provide the basis for the development of novel functional materials with unique photonic properties and applications in areas such as all-optical switching, photovoltaics and data storage.

  3. Temperature-dependent photoluminescence of highly luminescent water-soluble CdTe quantum dots

    Institute of Scientific and Technical Information of China (English)

    Ji Wei Liu; Yu Zhang; Cun Wang Ge; Yong Long Jin; Sun Ling Hu; Ning Gu

    2009-01-01

    Highly luminescent water-soluble CdTe quantum dots (QDs) have been synthesized with an electrogenerated precursor. The obtained CdTe QDs can possess good crystallizability, high quantum yield (QY) and favorable stability. Furthermore, a detection system is designed firstly for the investigation of the temperature-dependent PL of the QDs.

  4. Fractal features of CdTe thin films grown by RF magnetron sputtering

    Science.gov (United States)

    Hosseinpanahi, Fayegh; Raoufi, Davood; Ranjbarghanei, Khadijeh; Karimi, Bayan; Babaei, Reza; Hasani, Ebrahim

    2015-12-01

    Cadmium telluride (CdTe) thin films were prepared by RF magnetron sputtering on glass substrates at room temperature (RT). The film deposition was performed for 5, 10, and 15 min at power of 30 W with a frequency of 13.56 MHz. The crystal structure of the prepared CdTe thin films was studied by X-ray diffraction (XRD) technique. XRD analyses indicate that the CdTe films are polycrystalline, having zinc blende structure of CdTe irrespective of their deposition time. All CdTe films showed a preferred orientation along (1 1 1) crystalline plane. The surface morphology characterization of the films was studied using atomic force microscopy (AFM). The quantitative AFM characterization shows that the RMS surface roughness of the prepared CdTe thin films increases with increasing the deposition time. The detrended fluctuation analysis (DFA) and also multifractal detrended fluctuation analysis (MFDFA) methods showed that prepared CdTe thin films have multifractal nature. The complexity, roughness of the CdTe thin films and strength of the multifractality increase as deposition time increases.

  5. Fabrication of the structures with autocatalytic CdTe nanowires using magnetron sputtering deposition

    Science.gov (United States)

    Soshnikov, I. P.; Semenov, A. A.; Belyavskii, P. Yu.; Shtrom, I. V.; Kotlyar, K. P.; Lysak, V. V.; Kudryashov, D. A.; Pavlov, S. I.; Nashchekin, A. V.; Cirlin, G. E.

    2016-12-01

    We report the possibility of autocatalytic synthesis of highly crystalline perfect CdTe nanowires by magnetron presputtering deposition through the windows in ultrathin layers of SiO2. The photoluminescence spectra of obtained CdTe nanowires exhibit an emission band in the 1.4-1.7 eV region, indicating crystalline perfection of the nanowires.

  6. Translocation and neurotoxicity of CdTe quantum dots in RMEs motor neurons in nematode Caenorhabditis elegans

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yunli; Wang, Xiong; Wu, Qiuli; Li, Yiping; Wang, Dayong, E-mail: dayongw@seu.edu.cn

    2015-02-11

    Graphical abstract: - Highlights: • We investigated in vivo neurotoxicity of CdTe QDs on RMEs motor neurons in C. elegans. • CdTe QDs in the range of μg/L caused neurotoxicity on RMEs motor neurons. • Bioavailability of CdTe QDs may be the primary inducer for CdTe QDs neurotoxicity. • Both oxidative stress and cell identity regulate the CdTe QDs neurotoxicity. • CdTe QDs were translocated and deposited into RMEs motor neurons. - Abstract: We employed Caenorhabditis elegans assay system to investigate in vivo neurotoxicity of CdTe quantum dots (QDs) on RMEs motor neurons, which are involved in controlling foraging behavior, and the underlying mechanism of such neurotoxicity. After prolonged exposure to 0.1–1 μg/L of CdTe QDs, abnormal foraging behavior and deficits in development of RMEs motor neurons were observed. The observed neurotoxicity from CdTe QDs on RMEs motor neurons might be not due to released Cd{sup 2+}. Overexpression of genes encoding Mn-SODs or unc-30 gene controlling cell identity of RMEs neurons prevented neurotoxic effects of CdTe QDs on RMEs motor neurons, suggesting the crucial roles of oxidative stress and cell identity in regulating CdTe QDs neurotoxicity. In nematodes, CdTe QDs could be translocated through intestinal barrier and be deposited in RMEs motor neurons. In contrast, CdTe@ZnS QDs could not be translocated into RMEs motor neurons and therefore, could only moderately accumulated in intestinal cells, suggesting that ZnS coating might reduce neurotoxicity of CdTe QDs on RMEs motor neurons. Therefore, the combinational effects of oxidative stress, cell identity, and bioavailability may contribute greatly to the mechanism of CdTe QDs neurotoxicity on RMEs motor neurons. Our results provide insights into understanding the potential risks of CdTe QDs on the development and function of nervous systems in animals.

  7. Recent Results From a Si/CdTe Semiconductor Compton Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, T.; Watanabe, S.; Takeda, S.; Oonuki, K.; Mitani, T.; Nakazawa, K.; Takashima, T.; Takahashi, T.; Tajima, H.; Sawamoto, N.; Fukazawa, Y.; Nomachi, M.; /JAXA,

    2007-01-23

    We are developing a Compton telescope based on high resolution Si and CdTe detectors for astrophysical observations in sub-MeV/MeV gamma-ray region. Recently, we constructed a prototype Compton telescope which consists of six layers of double-sided Si strip detectors and CdTe pixel detectors to demonstrate the basic performance of this new technology. By irradiating the detector with gamma-rays from radio isotope sources, we have succeeded in Compton reconstruction of images and spectra. The obtained angular resolution is 3.9{sup o} (FWHM) at 511 keV, and the energy resolution is 14 keV (FWHM) at the same energy. In addition to the conventional Compton reconstruction, i.e., drawing cones in the sky, we also demonstrated a full reconstruction by tracking Compton recoil electrons using the signals detected in successive Si layers. By irradiating {sup 137}Cs source, we successfully obtained an image and a spectrum of 662 keV line emission with this method. As a next step, development of larger double-sided Si strip detectors with a size of 4 cm x 4 cm is underway to improve the effective area of the Compton telescope. We are also developing a new low-noise analog ASIC to handle the increasing number of channels. Initial results from these two new technologies are presented in this paper as well.

  8. Single CdTe microwire photodetectors grown by close-spaced sublimation method.

    Science.gov (United States)

    Yang, Gwangseok; Kim, Byung-Jae; Kim, Donghwan; Kim, Jihyun

    2014-08-11

    We demonstrate single CdTe microwire field-effect transistors (FETs) that are highly sensitive to ultraviolet (UV) light. Dense CdTe microwires were catalytically grown using a close-spaced sublimation system. Structural, morphological and transport properties in conjunction with the optoelectronic properties were systemically investigated. CdTe microwire FETs exhibited p-type behaviors with field-effect mobilities up to 1.1 × 10(-3) cm2 V(-1) s(-1). Optoelectronic properties of our CdTe microwire FETs were studied under dark and UV-illumination conditions, where photoresponse was highly dependent on the back-gate bias conditions. Our CdTe microwire FET-based photodetectors are promising for high-performance micro-optoelectronic applications.

  9. NREL Collaboration Breaks 1-Volt Barrier in CdTe Solar Technology

    Energy Technology Data Exchange (ETDEWEB)

    2016-05-01

    NREL scientists have worked with Washington State University and the University of Tennessee to improve the maximum voltage available from CdTe solar cells. Changes in dopants, stoichiometry, interface design, and defect chemistry improved the CdTe conductivity and carrier lifetime by orders of magnitude, thus enabling CdTe solar cells with open-circuit voltages exceeding 1 volt for the first time. Values of current density and fill factor for CdTe solar cells are already at high levels, but sub-par voltages has been a barrier to improved efficiencies. With voltages pushed beyond 1 volt, CdTe cells have a path to produce electricity at costs less than fossil fuels.

  10. Electrodeposition, characterization and photo electrochemical properties of CdSe and CdTe

    Directory of Open Access Journals (Sweden)

    Atef Y. Shenouda

    2015-03-01

    Full Text Available CdSe and CdTe are electrodeposited using 0.1 M Cd2+ and different ion concentrations of Se and Te. The effect of the temperature on the electrodeposition process is also studied. The crystal structure of the deposited CdSe and CdTe is investigated by X-ray diffraction (XRD. Scanning electron microscopy (SEM of samples deposited at optimized parameters reveals that CdSe has spongy spherical grains while CdTe has coralloid morphology. Optical absorption shows the presence of direct transition with band gap energy 1.96 and 1.51 eV for CdSe and CdTe, respectively. The highest photo-conversion efficiencies of electrodeposited CdSe and CdTe films per unit area are 6% and 9.6%, respectively that achieved under simple laboratory conditions.

  11. Diffusion of Cd and Te adatoms on CdTe(111 surfaces: A computational study using density functional theory

    Directory of Open Access Journals (Sweden)

    Ebadollah Naderi

    2015-01-01

    Full Text Available CdTe is one of the most promising semiconductor for thin-film based solar cells. Here we report a computational study of Cd and Te adatom diffusion on the CdTe (111 A-type (Cd terminated and B-type (Te terminated surfaces and their migration paths. The atomic and electronic structure calculations are performed under the DFT formalism and climbing Nudge Elastic Band (cNEB method has been applied to evaluate the potential barrier of the Te and Cd diffusion. In general the minimum energy site on the surface is labeled as Aa site. In case of Te and Cd on B-type surface, the sub-surface site (a site just below the top surface is very close in energy to the A site. This is responsible for the subsurface accumulation of adatoms and therefore, expected to influence the defect formation during growth. The diffusion process of adatoms is considered from Aa (occupied to Aa (empty site at the nearest distance. We have explored three possible migration paths for the adatom diffusion. The adatom surface interaction is highly dependent on the type of the surface. Typically, Te interaction with both type (5.2 eV for A-type and 3.8 eV for B-type is stronger than Cd interactions(2.4 eV for B-type and 0.39 eV for A-type. Cd interaction with the A-type surface is very weak. The distinct behavior of the A-type and B-type surfaces perceived in our study explain the need of maintaining the A-type surface during growth for smooth and stoichiometric growth.

  12. Diffusion of Cd and Te adatoms on CdTe(111) surfaces: A computational study using density functional theory

    Science.gov (United States)

    Naderi, Ebadollah; Nanavati, Sachin; Majumder, Chiranjib; Ghaisas, S. V.

    2015-01-01

    CdTe is one of the most promising semiconductor for thin-film based solar cells. Here we report a computational study of Cd and Te adatom diffusion on the CdTe (111) A-type (Cd terminated) and B-type (Te terminated) surfaces and their migration paths. The atomic and electronic structure calculations are performed under the DFT formalism and climbing Nudge Elastic Band (cNEB) method has been applied to evaluate the potential barrier of the Te and Cd diffusion. In general the minimum energy site on the surface is labeled as Aa site. In case of Te and Cd on B-type surface, the sub-surface site (a site just below the top surface) is very close in energy to the A site. This is responsible for the subsurface accumulation of adatoms and therefore, expected to influence the defect formation during growth. The diffusion process of adatoms is considered from Aa (occupied) to Aa (empty) site at the nearest distance. We have explored three possible migration paths for the adatom diffusion. The adatom surface interaction is highly dependent on the type of the surface. Typically, Te interaction with both type (5.2 eV for A-type and 3.8 eV for B-type) is stronger than Cd interactions(2.4 eV for B-type and 0.39 eV for A-type). Cd interaction with the A-type surface is very weak. The distinct behavior of the A-type and B-type surfaces perceived in our study explain the need of maintaining the A-type surface during growth for smooth and stoichiometric growth.

  13. Diffusion of Cd and Te adatoms on CdTe(111) surfaces: A computational study using density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Naderi, Ebadollah, E-mail: enaderi42@gmail.com [Department of Physics, Savitribai Phule Pune University (SPPU), Pune-411007 (India); Nanavati, Sachin [Center for Development of Advanced Computing (C-DAC), SPPU campus, Pune 411007 (India); Majumder, Chiranjib [Chemistry Division, Bhabha Atomic Research Center, Mumbai, 400085 (India); Ghaisas, S. V. [Department of Electronic Science, Savitribai Phule Pune University (SPPU), Pune-411007 (India); Department of Physics, Savitribai Phule Pune University (SPPU), Pune-411007 (India)

    2015-01-15

    CdTe is one of the most promising semiconductor for thin-film based solar cells. Here we report a computational study of Cd and Te adatom diffusion on the CdTe (111) A-type (Cd terminated) and B-type (Te terminated) surfaces and their migration paths. The atomic and electronic structure calculations are performed under the DFT formalism and climbing Nudge Elastic Band (cNEB) method has been applied to evaluate the potential barrier of the Te and Cd diffusion. In general the minimum energy site on the surface is labeled as A{sub a} site. In case of Te and Cd on B-type surface, the sub-surface site (a site just below the top surface) is very close in energy to the A site. This is responsible for the subsurface accumulation of adatoms and therefore, expected to influence the defect formation during growth. The diffusion process of adatoms is considered from A{sub a} (occupied) to A{sub a} (empty) site at the nearest distance. We have explored three possible migration paths for the adatom diffusion. The adatom surface interaction is highly dependent on the type of the surface. Typically, Te interaction with both type (5.2 eV for A-type and 3.8 eV for B-type) is stronger than Cd interactions(2.4 eV for B-type and 0.39 eV for A-type). Cd interaction with the A-type surface is very weak. The distinct behavior of the A-type and B-type surfaces perceived in our study explain the need of maintaining the A-type surface during growth for smooth and stoichiometric growth.

  14. Novel {beta}-cyclodextrin modified CdTe quantum dots as fluorescence nanosensor for acetylsalicylic acid and metabolites

    Energy Technology Data Exchange (ETDEWEB)

    Algarra, M. [Centro de Geologia do Porto, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Campos, B.B.; Aguiar, F.R.; Rodriguez-Borges, J.E. [Centro de Investigacao em Quimica (CIQ-UP), Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 169-007 Porto (Portugal); Esteves da Silva, J.C.G., E-mail: jcsilva@fc.up.pt [Centro de Investigacao em Quimica (CIQ-UP), Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 169-007 Porto (Portugal)

    2012-05-01

    {beta}-Cyclodextrin was modified with 11-[(ethoxycarbonyl)thio]undecanoic acid and used as a capping agent, together with mercaptosuccinic acid, to prepare water-stable CdTe quantum dots. The water soluble quantum dot obtained displays fluorescence with a maximum emission at 425 nm (under excitation at 300 nm) with lifetimes of 0.53, 4.8, 181, and 44.1 ns, respectively. The S-{beta}CD-MSA-CdTe can act as a nanoprobe that is due to the affinity of the cyclodextrin moiety for selected substances such as acetylsalicylic acid (ASA) and its metabolites as foreign species. The fluorescence of the S-{beta}CD-MSA-CdTe is enhanced on addition of ASA. Linear calibration plots are observed with ASA in concentrations between 0 and 1 mg/l, with a limit of detection at 8.5 Multiplication-Sign 10{sup -9} mol/l (1.5 ng/ml) and a precision as relative standard deviation of 1% (0.05 mg/l). The interference effect of certain compounds as ascorbic acid and its main metabolites such as salicylic, gentisic and salicyluric acid upon the obtained procedure was studied. Highlights: Black-Right-Pointing-Pointer Nanosensors constituted by CdTe quantum dots capped with modified cyclodextrin. Black-Right-Pointing-Pointer This nanomaterial shows fluorescence properties compatible with a semiconductor quantum dot. Black-Right-Pointing-Pointer The nanosensor shows fluorescence enhancement when inclusion complexes are formed with acetylsalicylic acid. Black-Right-Pointing-Pointer This nanomaterial has nanosensor potential taking into consideration the formation stability of the inclusion complex.

  15. Electronic structure of the valence band of II--VI wide band gap semiconductor interfaces

    OpenAIRE

    1996-01-01

    In this work we present the electronic band structure for (001)--CdTe interfaces with some other II--VI zinc blende semiconductors. We assume ideal interfaces. We use tight binding Hamiltonians with an orthogonal basis ($s p^3 s^*$). We make use of the well--known Surface Green's Function Matching method to calculate the interface band structure. In our calculation the dominion of the interface is constituted by four atomic layers. We consider here anion--anion interfaces only. We have includ...

  16. Pre-requisites for the formation of unusual diffusion profiles in II-VI semiconductors

    CERN Document Server

    Wolf, H; Kronenberg, J; Wagner, F; ISOLDE Collaboration

    2010-01-01

    The diffusion of the impurities Cu, Ag, Au, and Na in CdTe and CdZnTe exhibits the unusual phenomenon of uphill diffusion if the diffusion of the impurity is performed under external Cd pressure at temperatures typically in the range 700-900 K. A model is proposed that describes these concentration profiles quantitatively and yields pre-requisites for the observation of uphill diffusion. If a metal layer is evaporated onto the implanted surface, the diffusion of the impurity is strongly affected by the generation of intrinsic defects at the metal-semiconductor interface. (C) 2010 WILEY-VCH Verlag GmbH \\& Co. KGaA, Weinheim

  17. Pre-requisites for the formation of unusual diffusion profiles in II-VI semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, H.; Kronenberg, J.; Wagner, F.; Wichert, T. [Technische Physik, Universitaet des Saarlandes, Saarbruecken (Germany)

    2010-06-15

    The diffusion of the impurities Cu, Ag, Au, and Na in CdTe and CdZnTe exhibits the unusual phenomenon of uphill diffusion if the diffusion of the impurity is performed under external Cd pressure at temperatures typically in the range 700-900 K. A model is proposed that describes these concentration profiles quantitatively and yields pre-requisites for the observation of uphill diffusion. If a metal layer is evaporated onto the implanted surface, the diffusion of the impurity is strongly affected by the generation of intrinsic defects at the metal-semiconductor interface. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  18. The Ben Daniel-Duke Model Applied to Semiconductor Heterostructure - Part 2

    Directory of Open Access Journals (Sweden)

    Cornel Hatiegan

    2009-10-01

    Full Text Available We investigate the semiconductor heterostructure with the Ben DanielDuke model applied for the lowest conduction states Ga As-Ga (1 as and for the heavy levels at k⊥ = 0 in any heterostructures (1. In a quantic level we obtained the familiar staircase density of states (2. In (3 we calculated the incrgy position of the interface state in a single HgTe-CdTe heterojonction. We also obtained the existence of the interface state relies only on the relative position of the I’8 edges of HgTe and CdTe, their actual energy position, as well as their behavior at k⊥ ≠ 0 .

  19. Automatic Control System for the High Pressure CdTe Crystal Growth Furnace

    Directory of Open Access Journals (Sweden)

    Petr Praus

    2006-08-01

    Full Text Available CdTe and (CdZnTe bulk single crystals have been widely used as substrates for MBE and LPE epitaxy of infrared (HgCdTe as well as gamma- and X-ray detectors. The Cd1-xZnxTe (x = 0.04-0.1 single crystals with diameter up to 100 mm and height at most 40 mm were prepared in our laboratory in a vertical arrangement by gradual cooling of the melt (the Vertical Gradient Freezing method. Achievement of excellent crystal quality required full control of Cd pressure during the growth process and application of high Cd pressures (up to 4 bar at growth temperature. An electronic control system was designed to control both temperature and internal pressure of two zones CZT crystal growth furnace by using two high performance PID controllers/setpoint programmers. Two wire current loop serial communication bus was used for the data exchange and computer control of the furnace electronics setup. Control software was written to supervise the crystal growth process and to collect all important data and parameters.

  20. Recent developments in a CdTe-based x-ray detector for digital radiography

    Science.gov (United States)

    Glasser, Francis; Martin, Jean-Luc; Thevenin, Bernard; Schermesser, Patrick; Pantigny, Philippe; Laurent, Jean Yves; Rambaud, Philippe; Pitault, Bernard; Paltrier, Sylvain

    1997-05-01

    The performance of a new CdTe based x-ray detector devoted to digital radiography are presented. The detectors consist of a 6 cm2 CdTe 2D-array connected to CMOS readout circuit by indium bumps. The final image has 400 X 600 pixels with a 50 micron pitch. This solid-state detector presents the advantages of direct conversion, i.e. high stopping power with high spatial resolution and a significantly higher signal than commercially available scintillator/photodetector systems. The experimental results show excellent linearity, spatial resolution and detective quantum efficiency. The MTF was measured by the angled-slit method: 20 to 30 percent at 10 1p/mm depending on the incident x-ray energy. The measured DQE is about 0.8 at 40 KeV and 100 (mu) Gray dose. Our simulation shows that these experimental results do not reach the theoretical limit. Further improvements are in progress. The first industrial application will be dental radiography due to the small size and the excellent performances. We also tested the detector with x-rays form 20 KeV to 1.25 MeV. Of course the CdTe thickness should then be adapted to the incident x-ray energy.

  1. 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...

  2. Impact of metal overhang and guard ring techniques on breakdown voltage of Si strip sensors - 2003 IEEE nuclear science symposium, medical imaging conference, and workshop of room-temperature semiconductor detectors

    CERN Document Server

    Ranjan, K; Namrata, S; Chatterji, S; Srivastava-Ajay, K; Kumar, A; Jha, Manoj Kumar; Shivpuri, R K

    2004-01-01

    The importance of Si sensors in high-energy physics (HEP) experiments can hardly be overemphasized. However, the high luminosity and the high radiation level in the future HEP experiments, like Large Hadron Collider (LHC), has posed a serious challenge to the fabrication of Si detectors. For the safe operation over the full LHC lifetime, detectors are required to sustain very high voltage operation, well exceeding the bias voltage needed to full deplete the heavily irradiated Si sensors. Thus, the main effort in the development of Si sensors is concentrated on a design that avoids p-n junction breakdown at operational biases. Among various proposed techniques, Field-limiting Ring (FLR) (or guard ring) and Metal-Overhang (MO) are technologically simple and are suitable for vertical devices. Since high-voltage planar Si junctions are of great importance in the HEP experiments, it is very interesting to compare these two aforementioned techniques for achieving the maximum breakdown voltage under optimal conditio...

  3. Enhancement of superconducting critical current by injection of quasiparticles in superconductor semiconductor devices

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Sørensen, C. B.

    2000-01-01

    We report new measurements on 3-terminal superconductor semiconductor injection devices, demonstrating enhancement of the supercurrent by injection from a superconducting injector electrode. Two other electrodes were used as detectors. Applying a small voltage to the injector, reduced the maximum...

  4. 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...From - To) 15-07-2013 to 14-07-2016 4. TITLE AND SUBTITLE Infrared Semiconductor Metamaterials 5a. CONTRACT NUMBER FA9550-13-1-0182 5b. GRANT...program are 1) establishing an approach for widely tunable resonators and metasurfaces 2) experimentally demonstrating widely tunable semiconductor

  5. Processing of Complex Compound Semiconductors in Space

    Science.gov (United States)

    Bachmann, K.

    1985-01-01

    The purpose of this first year ground based research effort was to develop growth and characterization facilities for bulk single crystals of compound semiconductor alloys. As a system of 2-6 alloy crystal growth, C sub x Mn sub (1-x)Te was chosen since it has a relatively narrow solidus-liquidus separation serving as a suitable first model for zone melting and solution growth. Also, it allows, in principle, perfect lattice matching to Cd sub x Hg sub(1-x)Te that needs to be studied as a model for the investigation of heteroepitaxial growth from Te-solutions. A vertical zone melting furnace was built and used in the synthesis of Cd sub x Mn sub(1-x)Te from the elements and crystal growth in carbon coated fused silica crucibles of Bridgman growth geometry. Photoluminescence spectra of the crystals reveal band to band recombination at energies that agree with the reported literature data. In addition, deep luminescence is present at energies corresponding to proportional shifts from the 1.4 eV deep emission observed for bulk single crystals of CdTe.

  6. Development of semiconductor radiation sensors for portable alarm-dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y. K.; Moon, B. S.; Chung, C. E.; Hong, S. B.; Kim, J. Y.; Kim, J. B.; Han, S. H.; Lee, W. G. [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2001-01-01

    We studied Semiconductor Radiation Sensors for Portable Alarm-Dosimeter. We calculated response functions for gamma energy 0.021, 0.122, 0.662, 0.835, 1.2 MeV using EGS4 codes. When we measured at various distance from source to detector, the detection efficiency of Si semiconductor detector was better than that of GM tube. The linear absorption coefficients of steel and aluminum plate were measured. These experimental results of the response of detector for intensity of radiation field coincide to the theoretical expectation. The count value of Si detector was changed with changing thickness of steel as changing threshold voltage of discriminator, and the linear absorption coefficient increased with increasing threshold voltage. Radiation detection efficiency shows difference at each threshold voltage condition. This results coincided to the theoretical simulation. 33 refs., 27 figs., 8 tabs. (Author)

  7. Operation and performance of the ATLAS semiconductor tracker

    CERN Document Server

    Aad, Georges; Abdallah, Jalal; Abdel Khalek, Samah; Abdinov, Ovsat; Aben, Rosemarie; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Abreu, Ricardo; Abulaiti, Yiming; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Adelman, Jahred; Adomeit, Stefanie; Adye, Tim; Agatonovic-Jovin, Tatjana; Aguilar-Saavedra, Juan Antonio; Agustoni, Marco; Ahlen, Steven; Ahmad, Ashfaq; Ahmadov, Faig; Aielli, Giulio; Åkesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Alberghi, Gian Luigi; Albert, Justin; Albrand, Solveig; Alconada Verzini, Maria Josefina; Aleksa, Martin; Aleksandrov, Igor; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Alimonti, Gianluca; Alio, Lion; Alison, John; Allbrooke, Benedict; Allison, Lee John; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alonso, Alejandro; Alonso, Francisco; Alpigiani, Cristiano; Altheimer, Andrew David; Alvarez Gonzalez, Barbara; Alviggi, Mariagrazia; Amako, Katsuya; Amaral Coutinho, Yara; Amelung, Christoph; Amidei, Dante; Amor Dos Santos, Susana Patricia; Amorim, Antonio; Amoroso, Simone; Amram, Nir; Amundsen, Glenn; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Anduaga, Xabier; Angelidakis, Stylianos; Angelozzi, Ivan; Anger, Philipp; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoki, Masato; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Araque, Juan Pedro; Arce, Ayana; Arguin, Jean-Francois; Argyropoulos, Spyridon; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnal, Vanessa; Arnold, Hannah; Arslan, Ozan; Artamonov, Andrei; Artoni, Giacomo; Asai, Shoji; Asbah, Nedaa; Ashkenazi, Adi; Ask, Stefan; Åsman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astalos, Robert; Atkinson, Markus; Atlay, Naim Bora; Auerbach, Benjamin; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Azuelos, Georges; Azuma, Yuya; Baak, Max; Bacci, Cesare; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Backus Mayes, John; Badescu, Elisabeta; Bagiacchi, Paolo; Bagnaia, Paolo; Bai, Yu; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Sarah; Balek, Petr; Balli, Fabrice; Banas, Elzbieta; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bannoura, Arwa A E; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Barnovska, Zuzana; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Bartoldus, Rainer; Barton, Adam Edward; Bartos, Pavol; Bartsch, Valeria; Bassalat, Ahmed; Basye, Austin; Bates, Richard; Batkova, Lucia; Batley, Richard; Battistin, Michele; Bauer, Florian; Bawa, Harinder Singh; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Becker, Anne Kathrin; Becker, Sebastian; Beckingham, Matthew; Becot, Cyril; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Beemster, Lars; Beermann, Thomas; Begel, Michael; Behr, Katharina; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellerive, Alain; Bellomo, Massimiliano; Belloni, Alberto; Belotskiy, Konstantin; Beltramello, Olga; Benary, Odette; Benchekroun, Driss; Bendtz, Katarina; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez Garcia, Jorge-Armando; Benjamin, Douglas; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, Jürg; Bernabéu, José; Bernard, Clare; Bernat, Pauline; Bernius, Catrin; Bernlochner, Florian Urs; Berry, Tracey; Berta, Peter; Bertella, Claudia; Bertolucci, Federico; Besana, Maria Ilaria; Besjes, Geert-Jan; Bessidskaia, Olga; Besson, Nathalie; Betancourt, Christopher; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianchini, Louis; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Bierwagen, Katharina; Biesiada, Jed; Biglietti, Michela; Bilbao De Mendizabal, Javier; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare; Black, Curtis; Black, James; Black, Kevin; Blackburn, Daniel; Blair, Robert; Blanchard, Jean-Baptiste; Blazek, Tomas; Bloch, Ingo; Blocker, Craig; Blum, Walter; Blumenschein, Ulrike; Bobbink, Gerjan; Bobrovnikov, Victor; Bocchetta, Simona Serena; Bocci, Andrea; Boddy, Christopher Richard; Boehler, Michael; Boek, Jennifer; Boek, Thorsten Tobias; Bogaerts, Joannes Andreas; Bogdanchikov, Alexander; Bogouch, Andrei; Bohm, Christian; Bohm, Jan; Boisvert, Veronique; Bold, Tomasz; Boldea, Venera; Boldyrev, Alexey; Bomben, Marco; Bona, Marcella; Boonekamp, Maarten; Borisov, Anatoly; Borissov, Guennadi; Borri, Marcello; Borroni, Sara; Bortfeldt, Jonathan; Bortolotto, Valerio; Bos, Kors; Boscherini, Davide; Bosman, Martine; Boterenbrood, Hendrik; Boudreau, Joseph; Bouffard, Julian; Bouhova-Thacker, Evelina Vassileva; Boumediene, Djamel Eddine; Bourdarios, Claire; Bousson, Nicolas; Boutouil, Sara; Boveia, Antonio; Boyd, James; Boyko, Igor; Bozovic-Jelisavcic, Ivanka; Bracinik, Juraj; Branchini, Paolo; Brandt, Andrew; Brandt, Gerhard; Brandt, Oleg; Bratzler, Uwe; Brau, Benjamin; Brau, James; Braun, Helmut; Brazzale, Simone Federico; Brelier, Bertrand; Brendlinger, Kurt; Brennan, Amelia Jean; Brenner, Richard; Bressler, Shikma; Bristow, Kieran; Bristow, Timothy Michael; Britton, Dave; Brochu, Frederic; Brock, Ian; Brock, Raymond; Bromberg, Carl; Bronner, Johanna; Brooijmans, Gustaaf; Brooks, Timothy; Brooks, William; Brosamer, Jacquelyn; Brost, Elizabeth; Brown, Gareth; Brown, Jonathan; Bruckman de Renstrom, Pawel; Bruncko, Dusan; Bruneliere, Renaud; Brunet, Sylvie; Bruni, Alessia; Bruni, Graziano; Bruschi, Marco; Bryngemark, Lene; Buanes, Trygve; Buat, Quentin; Bucci, Francesca; Buchholz, Peter; Buckingham, Ryan; Buckley, Andrew; Buda, Stelian Ioan; Budagov, Ioulian; Buehrer, Felix; Bugge, Lars; Bugge, Magnar Kopangen; Bulekov, Oleg; Bundock, Aaron Colin; Burckhart, Helfried; Burdin, Sergey; Burghgrave, Blake; Burke, Stephen; Burmeister, Ingo; Busato, Emmanuel; Büscher, Daniel; Büscher, Volker; Bussey, Peter; Buszello, Claus-Peter; Butler, Bart; Butler, John; Butt, Aatif Imtiaz; Buttar, Craig; Butterworth, Jonathan; Butti, Pierfrancesco; Buttinger, William; Buzatu, Adrian; Byszewski, Marcin; Cabrera Urbán, Susana; Caforio, Davide; Cakir, Orhan; Calafiura, Paolo; Calandri, Alessandro; Calderini, Giovanni; Calfayan, Philippe; Calkins, Robert; Caloba, Luiz; Calvet, David; Calvet, Samuel; Camacho Toro, Reina; Camarda, Stefano; Cameron, David; Caminada, Lea Michaela; Caminal Armadans, Roger; Campana, Simone; Campanelli, Mario; Campoverde, Angel; Canale, Vincenzo; Canepa, Anadi; Cantero, Josu; Cantrill, Robert; Cao, Tingting; Capeans Garrido, Maria Del Mar; Caprini, Irinel; Caprini, Mihai; Capua, Marcella; Caputo, Regina; Cardarelli, Roberto; Carli, Tancredi; Carlino, Gianpaolo; Carminati, Leonardo; Caron, Sascha; Carquin, Edson; Carrillo-Montoya, German D; Carter, Antony; Carter, Janet; Carvalho, João; Casadei, Diego; Casado, Maria Pilar; Castaneda-Miranda, Elizabeth; Castelli, Angelantonio; Castillo Gimenez, Victoria; Castro, Nuno Filipe; Catastini, Pierluigi; Catinaccio, Andrea; Catmore, James; Cattai, Ariella; Cattani, Giordano; Caughron, Seth; Cavaliere, Viviana; Cavalli, Donatella; Cavalli-Sforza, Matteo; Cavasinni, Vincenzo; Ceradini, Filippo; Cerio, Benjamin; Cerny, Karel; Cerqueira, Augusto Santiago; Cerri, Alessandro; Cerrito, Lucio; Cerutti, Fabio; Cerv, Matevz; Cervelli, Alberto; Cetin, Serkant Ali; Chafaq, Aziz; Chakraborty, Dhiman; Chalupkova, Ina; Chan, Kevin; Chang, Philip; Chapleau, Bertrand; Chapman, John Derek; Charfeddine, Driss; Charlton, Dave; Chau, Chav Chhiv; Chavez Barajas, Carlos Alberto; Cheatham, Susan; Chegwidden, Andrew; Chekanov, Sergei; Chekulaev, Sergey; Chelkov, Gueorgui; Chelstowska, Magda Anna; Chen, Chunhui; Chen, Hucheng; Chen, Karen; Chen, Liming; Chen, Shenjian; Chen, Xin; Chen, Yujiao; Cheng, Hok Chuen; Cheng, Yangyang; Cheplakov, Alexander; Cherkaoui El Moursli, Rajaa; Chernyatin, Valeriy; Cheu, Elliott; Chevalier, Laurent; Chiarella, Vitaliano; Chiefari, Giovanni; Childers, John Taylor; Chilingarov, Alexandre; Chiodini, Gabriele; Chisholm, Andrew; Chislett, Rebecca Thalatta; Chitan, Adrian; Chizhov, Mihail; Chouridou, Sofia; Chow, Bonnie Kar Bo; Christidi, Ilektra-Athanasia; Chromek-Burckhart, Doris; Chu, Ming-Lee; Chudoba, Jiri; Chwastowski, Janusz; Chytka, Ladislav; Ciapetti, Guido; Ciftci, Abbas Kenan; Ciftci, Rena; Cinca, Diane; Cindro, Vladimir; Ciocio, Alessandra; Cirkovic, Predrag; Citron, Zvi Hirsh; Citterio, Mauro; Ciubancan, Mihai; Clark, Allan G; Clark, Philip James; Clarke, Robert; Cleland, Bill; Clemens, Jean-Claude; Clement, Christophe; Coadou, Yann; Cobal, Marina; Coccaro, Andrea; Cochran, James H; Coffey, Laurel; Cogan, Joshua Godfrey; Coggeshall, James; Cole, Brian; Cole, Stephen; Colijn, Auke-Pieter; Collins-Tooth, Christopher; Collot, Johann; Colombo, Tommaso; Colon, German; Compostella, Gabriele; Conde Muiño, Patricia; Coniavitis, Elias; Conidi, Maria Chiara; Connell, Simon Henry; Connelly, Ian; Consonni, Sofia Maria; Consorti, Valerio; Constantinescu, Serban; Conta, Claudio; Conti, Geraldine; Conventi, Francesco; Cooke, Mark; Cooper, Ben; Cooper-Sarkar, Amanda; Cooper-Smith, Neil; Copic, Katherine; Cornelissen, Thijs; Corradi, Massimo; Corriveau, Francois; Corso-Radu, Alina; Cortes-Gonzalez, Arely; Cortiana, Giorgio; Costa, Giuseppe; Costa, María José; Costanzo, Davide; Côté, David; Cottin, Giovanna; Cowan, Glen; Cox, Brian; Cranmer, Kyle; Cree, Graham; Crépé-Renaudin, Sabine; Crescioli, Francesco; Crispin Ortuzar, Mireia; Cristinziani, Markus; Croft, Vince; Crosetti, Giovanni; Cuciuc, Constantin-Mihai; Cuenca Almenar, Cristóbal; Cuhadar Donszelmann, Tulay; Cummings, Jane; Curatolo, Maria; Cuthbert, Cameron; Czirr, Hendrik; Czodrowski, Patrick; Czyczula, Zofia; D'Auria, Saverio; D'Onofrio, Monica; Da Cunha Sargedas De Sousa, Mario Jose; Da Via, Cinzia; Dabrowski, Wladyslaw; Dafinca, Alexandru; Dai, Tiesheng; Dale, Orjan; Dallaire, Frederick; Dallapiccola, Carlo; Dam, Mogens; Daniells, Andrew Christopher; Dano Hoffmann, Maria; Dao, Valerio; Darbo, Giovanni; Darlea, Georgiana Lavinia; Darmora, Smita; Dassoulas, James; Dattagupta, Aparajita; Davey, Will; David, Claire; Davidek, Tomas; Davies, Eleanor; Davies, Merlin; Davignon, Olivier; Davison, Adam; Davison, Peter; Davygora, Yuriy; Dawe, Edmund; Dawson, Ian; Daya-Ishmukhametova, Rozmin; De, Kaushik; de Asmundis, Riccardo; De Castro, Stefano; De Cecco, Sandro; de Graat, Julien; De Groot, Nicolo; de Jong, Paul; De la Torre, Hector; De Lorenzi, Francesco; De Nooij, Lucie; De Pedis, Daniele; De Salvo, Alessandro; De Sanctis, Umberto; De Santo, Antonella; De Vivie De Regie, Jean-Baptiste; De Zorzi, Guido; Dearnaley, William James; Debbe, Ramiro; Debenedetti, Chiara; Dechenaux, Benjamin; Dedovich, Dmitri; Degenhardt, James; Deigaard, Ingrid; Del Peso, Jose; Del Prete, Tarcisio; Deliot, Frederic; Delitzsch, Chris Malena; Deliyergiyev, Maksym; Dell'Acqua, Andrea; Dell'Asta, Lidia; Dell'Orso, Mauro; Della Pietra, Massimo; della Volpe, Domenico; Delmastro, Marco; Delsart, Pierre-Antoine; Deluca, Carolina; Demers, Sarah; Demichev, Mikhail; Demilly, Aurelien; Denisov, Sergey; Derendarz, Dominik; Derkaoui, Jamal Eddine; Derue, Frederic; Dervan, Paul; Desch, Klaus Kurt; Deterre, Cecile; Deviveiros, Pier-Olivier; Dewhurst, Alastair; Dhaliwal, Saminder; Di Ciaccio, Anna; Di Ciaccio, Lucia; Di Domenico, Antonio; Di Donato, Camilla; Di Girolamo, Alessandro; Di Girolamo, Beniamino; Di Mattia, Alessandro; Di Micco, Biagio; Di Nardo, Roberto; Di Simone, Andrea; Di Sipio, Riccardo; Di Valentino, David; Diaz, Marco Aurelio; Diehl, Edward; Dietrich, Janet; Dietzsch, Thorsten; Diglio, Sara; Dimitrievska, Aleksandra; Dingfelder, Jochen; Dionisi, Carlo; Dita, Petre; Dita, Sanda; Dittus, Fridolin; Djama, Fares; Djobava, Tamar; do Vale, Maria Aline Barros; Do Valle Wemans, André; Doan, Thi Kieu Oanh; Dobos, Daniel; Dobson, Ellie; Doglioni, Caterina; Doherty, Tom; Dohmae, Takeshi; Dolejsi, Jiri; Dolezal, Zdenek; Dolgoshein, Boris; Donadelli, Marisilvia; Donati, Simone; Dondero, Paolo; Donini, Julien; Dopke, Jens; Doria, Alessandra; Dos Anjos, Andre; Dova, Maria-Teresa; Doyle, Tony; Dris, Manolis; Dubbert, Jörg; Dube, Sourabh; Dubreuil, Emmanuelle; Duchovni, Ehud; Duckeck, Guenter; Ducu, Otilia Anamaria; Duda, Dominik; Dudarev, Alexey; Dudziak, Fanny; Duflot, Laurent; Duguid, Liam; Dührssen, Michael; Dunford, Monica; Duran Yildiz, Hatice; Düren, Michael; Durglishvili, Archil; Dwuznik, Michal; Dyndal, Mateusz; Ebke, Johannes; Edson, William; Edwards, Nicholas Charles; Ehrenfeld, Wolfgang; Eifert, Till; Eigen, Gerald; Einsweiler, Kevin; Ekelof, Tord; El Kacimi, Mohamed; Ellert, Mattias; Elles, Sabine; Ellinghaus, Frank; Ellis, Nicolas; Elmsheuser, Johannes; Elsing, Markus; Emeliyanov, Dmitry; Enari, Yuji; Endner, Oliver Chris; Endo, Masaki; Engelmann, Roderich; Erdmann, Johannes; Ereditato, Antonio; Eriksson, Daniel; Ernis, Gunar; Ernst, Jesse; Ernst, Michael; Ernwein, Jean; Errede, Deborah; Errede, Steven; Ertel, Eugen; Escalier, Marc; Esch, Hendrik; Escobar, Carlos; Esposito, Bellisario; Etienvre, Anne-Isabelle; Etzion, Erez; Evans, Hal; Fabbri, Laura; Facini, Gabriel; Fakhrutdinov, Rinat; Falciano, Speranza; Faltova, Jana; Fang, Yaquan; Fanti, Marcello; Farbin, Amir; Farilla, Addolorata; Farooque, Trisha; Farrell, Steven; Farrington, Sinead; Farthouat, Philippe; Fassi, Farida; Fassnacht, Patrick; Fassouliotis, Dimitrios; Favareto, Andrea; Fayard, Louis; Federic, Pavol; Fedin, Oleg; Fedorko, Wojciech; Fehling-Kaschek, Mirjam; Feigl, Simon; Feligioni, Lorenzo; Feng, Cunfeng; Feng, Eric; Feng, Haolu; Fenyuk, Alexander; Fernandez Perez, Sonia; Ferrag, Samir; Ferrando, James; Ferrari, Arnaud; Ferrari, Pamela; Ferrari, Roberto; Ferreira de Lima, Danilo Enoque; Ferrer, Antonio; Ferrere, Didier; Ferretti, Claudio; Ferretto Parodi, Andrea; Fiascaris, Maria; Fiedler, Frank; Filipčič, Andrej; Filipuzzi, Marco; Filthaut, Frank; Fincke-Keeler, Margret; Finelli, Kevin Daniel; Fiolhais, Miguel; Fiorini, Luca; Firan, Ana; Fischer, Julia; Fisher, Wade Cameron; Fitzgerald, Eric Andrew; Flechl, Martin; Fleck, Ivor; Fleischmann, Philipp; Fleischmann, Sebastian; Fletcher, Gareth Thomas; Fletcher, Gregory; Flick, Tobias; Floderus, Anders; Flores Castillo, Luis; Florez Bustos, Andres Carlos; Flowerdew, Michael; Formica, Andrea; Forti, Alessandra; Fortin, Dominique; Fournier, Daniel; Fox, Harald; Fracchia, Silvia; Francavilla, Paolo; Franchini, Matteo; Franchino, Silvia; Francis, David; Franklin, Melissa; Franz, Sebastien; Fraternali, Marco; French, Sky; Friedrich, Conrad; Friedrich, Felix; Froidevaux, Daniel; Frost, James; Fukunaga, Chikara; Fullana Torregrosa, Esteban; Fulsom, Bryan Gregory; Fuster, Juan; Gabaldon, Carolina; Gabizon, Ofir; Gabrielli, Alessandro; Gabrielli, Andrea; Gadatsch, Stefan; Gadomski, Szymon; Gagliardi, Guido; Gagnon, Pauline; Galea, Cristina; Galhardo, Bruno; Gallas, Elizabeth; Gallo, Valentina Santina; Gallop, Bruce; Gallus, Petr; Galster, Gorm Aske Gram Krohn; Gan, KK; Gandrajula, Reddy Pratap; Gao, Jun; Gao, Yongsheng; Garay Walls, Francisca; Garberson, Ford; García, Carmen; Garcia Argos, Carlos; García Navarro, José Enrique; Garcia-Sciveres, Maurice; Gardner, Robert; Garelli, Nicoletta; Garonne, Vincent; Gatti, Claudio; Gaudio, Gabriella; Gaur, Bakul; Gauthier, Lea; Gauzzi, Paolo; Gavrilenko, Igor; Gay, Colin; Gaycken, Goetz; Gazis, Evangelos; Ge, Peng; Gecse, Zoltan; Gee, Norman; Geerts, Daniël Alphonsus Adrianus; Geich-Gimbel, Christoph; Gellerstedt, Karl; Gemme, Claudia; Gemmell, Alistair; Genest, Marie-Hélène; Gentile, Simonetta; George, Matthias; George, Simon; Gerbaudo, Davide; Gershon, Avi; Ghazlane, Hamid; Ghodbane, Nabil; Giacobbe, Benedetto; Giagu, Stefano; Giangiobbe, Vincent; Giannetti, Paola; Gianotti, Fabiola; Gibbard, Bruce; Gibson, Stephen; Gilchriese, Murdock; Gillam, Thomas; Gillberg, Dag; Gilles, Geoffrey; Gingrich, Douglas; Giokaris, Nikos; Giordani, MarioPaolo; Giordano, Raffaele; Giorgi, Francesco Michelangelo; Giraud, Pierre-Francois; Giugni, Danilo; Giuliani, Claudia; Giulini, Maddalena; Gjelsten, Børge Kile; Gkialas, Ioannis; Gladilin, Leonid; Glasman, Claudia; Glatzer, Julian; Glaysher, Paul; Glazov, Alexandre; Glonti, George; Goblirsch-Kolb, Maximilian; Goddard, Jack Robert; Godfrey, Jennifer; Godlewski, Jan; Goeringer, Christian; Goldfarb, Steven; Golling, Tobias; Golubkov, Dmitry; Gomes, Agostinho; Gomez Fajardo, Luz Stella; Gonçalo, Ricardo; Goncalves Pinto Firmino Da Costa, Joao; Gonella, Laura; González de la Hoz, Santiago; Gonzalez Parra, Garoe; Gonzalez Silva, Laura; Gonzalez-Sevilla, Sergio; Goodrick, Maurice; Goossens, Luc; Gorbounov, Petr Andreevich; Gordon, Howard; Gorelov, Igor; Gorfine, Grant; Gorini, Benedetto; Gorini, Edoardo; Gorišek, Andrej; Gornicki, Edward; Goshaw, Alfred; Gössling, Claus; Gostkin, Mikhail Ivanovitch; Gouighri, Mohamed; Goujdami, Driss; Goulette, Marc Phillippe; Goussiou, Anna; Goy, Corinne; Gozpinar, Serdar; Grabas, Herve Marie Xavier; Graber, Lars; Grabowska-Bold, Iwona; Grafström, Per; Grahn, Karl-Johan; Gramling, Johanna; Gramstad, Eirik; Grancagnolo, Sergio; Grassi, Valerio; Gratchev, Vadim; Gray, Heather; Graziani, Enrico; Grebenyuk, Oleg; Greenwood, Zeno Dixon; Gregersen, Kristian; Gregor, Ingrid-Maria; Grenier, Philippe; Griffiths, Justin; Grigalashvili, Nugzar; Grillo, Alexander; Grimm, Kathryn; Grinstein, Sebastian; Gris, Philippe Luc Yves; Grishkevich, Yaroslav; Grivaz, Jean-Francois; Grohs, Johannes Philipp; Grohsjean, Alexander; Gross, Eilam; Grosse-Knetter, Joern; Grossi, Giulio Cornelio; Groth-Jensen, Jacob; Grout, Zara Jane; Grybel, Kai; Guan, Liang; Guescini, Francesco; Guest, Daniel; Gueta, Orel; Guicheney, Christophe; Guido, Elisa; Guillemin, Thibault; Guindon, Stefan; Gul, Umar; Gumpert, Christian; Gunther, Jaroslav; Guo, Jun; Gupta, Shaun; Gutierrez, Phillip; Gutierrez Ortiz, Nicolas Gilberto; Gutschow, Christian; Guttman, Nir; Guyot, Claude; Gwenlan, Claire; Gwilliam, Carl; Haas, Andy; Haber, Carl; Hadavand, Haleh Khani; Haddad, Nacim; Haefner, Petra; Hageboeck, Stephan; Hajduk, Zbigniew; Hakobyan, Hrachya; Haleem, Mahsana; Hall, David; Halladjian, Garabed; Hamacher, Klaus; Hamal, Petr; Hamano, Kenji; Hamer, Matthias; Hamilton, Andrew; Hamilton, Samuel; Hamnett, Phillip George; Han, Liang; Hanagaki, Kazunori; Hanawa, Keita; Hance, Michael; Hanke, Paul; Hansen, Jørgen Beck; Hansen, Jorn Dines; Hansen, Peter Henrik; Hara, Kazuhiko; Hard, Andrew; Harenberg, Torsten; Harkusha, Siarhei; Harper, Devin; Harrington, Robert; Harris, Orin; Harrison, Paul Fraser; Hartjes, Fred; Hasegawa, Satoshi; Hasegawa, Yoji; Hasib, A; Hassani, Samira; Haug, Sigve; Hauschild, Michael; Hauser, Reiner; Havranek, Miroslav; Hawkes, Christopher; Hawkings, Richard John; Hawkins, Anthony David; Hayashi, Takayasu; Hayden, Daniel; Hays, Chris; Hayward, Helen; Haywood, Stephen; Head, Simon; Heck, Tobias; Hedberg, Vincent; Heelan, Louise; Heim, Sarah; Heim, Timon; Heinemann, Beate; Heinrich, Lukas; Heisterkamp, Simon; Hejbal, Jiri; Helary, Louis; Heller, Claudio; Heller, Matthieu; Hellman, Sten; Hellmich, Dennis; Helsens, Clement; Henderson, James; Henderson, Robert; Hengler, Christopher; Henrichs, Anna; Henriques Correia, Ana Maria; Henrot-Versille, Sophie; Hensel, Carsten; Herbert, Geoffrey Henry; Hernández Jiménez, Yesenia; Herrberg-Schubert, Ruth; Herten, Gregor; Hertenberger, Ralf; Hervas, Luis; Hesketh, Gavin Grant; Hessey, Nigel; Hickling, Robert; Higón-Rodriguez, Emilio; Hill, Ewan; Hill, John; Hiller, Karl Heinz; Hillert, Sonja; Hillier, Stephen; Hinchliffe, Ian; Hines, Elizabeth; Hirose, Minoru; Hirschbuehl, Dominic; Hobbs, John; Hod, Noam; Hodgkinson, Mark; Hodgson, Paul; Hoecker, Andreas; Hoeferkamp, Martin; Hoffman, Julia; Hoffmann, Dirk; Hofmann, Julia Isabell; Hohlfeld, Marc; Holmes, Tova Ray; Hong, Tae Min; Hooft van Huysduynen, Loek; Hostachy, Jean-Yves; Hou, Suen; Hoummada, Abdeslam; Howard, Jacob; Howarth, James; Hrabovsky, Miroslav; Hristova, Ivana; Hrivnac, Julius; Hryn'ova, Tetiana; Hsu, Pai-hsien Jennifer; Hsu, Shih-Chieh; Hu, Diedi; Hu, Xueye; Huang, Yanping; Hubacek, Zdenek; Hubaut, Fabrice; Huegging, Fabian; Huffman, Todd Brian; Hughes, Emlyn; Hughes, Gareth; Huhtinen, Mika; Hülsing, Tobias Alexander; Hurwitz, Martina; Huseynov, Nazim; Huston, Joey; Huth, John; Iacobucci, Giuseppe; Iakovidis, Georgios; Ibragimov, Iskander; Iconomidou-Fayard, Lydia; Idarraga, John; Ideal, Emma; Iengo, Paolo; Igonkina, Olga; Iizawa, Tomoya; Ikegami, Yoichi; Ikematsu, Katsumasa; Ikeno, Masahiro; Iliadis, Dimitrios; Ilic, Nikolina; Inamaru, Yuki; Ince, Tayfun; Ioannou, Pavlos; Iodice, Mauro; Iordanidou, Kalliopi; Ippolito, Valerio; Irles Quiles, Adrian; Isaksson, Charlie; Ishino, Masaya; Ishitsuka, Masaki; Ishmukhametov, Renat; Issever, Cigdem; Istin, Serhat; Iturbe Ponce, Julia Mariana; Ivarsson, Jenny; Ivashin, Anton; Iwanski, Wieslaw; Iwasaki, Hiroyuki; Izen, Joseph; Izzo, Vincenzo; Jackson, Brett; Jackson, John; Jackson, Matthew; Jackson, Paul; Jaekel, Martin; Jain, Vivek; Jakobs, Karl; Jakobsen, Sune; Jakoubek, Tomas; Jakubek, Jan; Jamin, David Olivier; Jana, Dilip; Jansen, Eric; Jansen, Hendrik; Janssen, Jens; Janus, Michel; Jarlskog, Göran; Javadov, Namig; Javůrek, Tomáš; Jeanty, Laura; Jeng, Geng-yuan; Jennens, David; Jenni, Peter; Jentzsch, Jennifer; Jeske, Carl; Jézéquel, Stéphane; Ji, Haoshuang; Ji, Weina; Jia, Jiangyong; Jiang, Yi; Jimenez Belenguer, Marcos; Jin, Shan; Jinaru, Adam; Jinnouchi, Osamu; Joergensen, Morten Dam; Johansson, Erik; Johansson, Per; Johns, Kenneth; Jon-And, Kerstin; Jones, Graham; Jones, Roger; Jones, Tim; Jongmanns, Jan; Jorge, Pedro; Joseph, John; Joshi, Kiran Daniel; Jovicevic, Jelena; Ju, Xiangyang; Jung, Christian; Jungst, Ralph Markus; Jussel, Patrick; Juste Rozas, Aurelio; Kaci, Mohammed; Kaczmarska, Anna; Kado, Marumi; Kagan, Harris; Kagan, Michael; Kajomovitz, Enrique; Kama, Sami; Kanaya, Naoko; Kaneda, Michiru; Kaneti, Steven; Kanno, Takayuki; Kantserov, Vadim; Kanzaki, Junichi; Kaplan, Benjamin; Kapliy, Anton; Kar, Deepak; Karakostas, Konstantinos; Karastathis, Nikolaos; Karnevskiy, Mikhail; Karpov, Sergey; Karthik, Krishnaiyengar; Kartvelishvili, Vakhtang; Karyukhin, Andrey; Kashif, Lashkar; Kasieczka, Gregor; Kass, Richard; Kastanas, Alex; Kataoka, Yousuke; Katre, Akshay; Katzy, Judith; Kaushik, Venkatesh; Kawagoe, Kiyotomo; Kawamoto, Tatsuo; Kawamura, Gen; Kazama, Shingo; Kazanin, Vassili; Kazarinov, Makhail; Keeler, Richard; Keener, Paul; Kehoe, Robert; Keil, Markus; Keller, John; Keoshkerian, Houry; Kepka, Oldrich; Kerševan, Borut Paul; Kersten, Susanne; Kessoku, Kohei; Keung, Justin; Khalil-zada, Farkhad; Khandanyan, Hovhannes; Khanov, Alexander; Khodinov, Alexander; Khomich, Andrei; Khoo, Teng Jian; Khoriauli, Gia; Khoroshilov, Andrey; Khovanskiy, Valery; Khramov, Evgeniy; Khubua, Jemal; Kim, Hee Yeun; Kim, Hyeon Jin; Kim, Shinhong; Kimura, Naoki; Kind, Oliver; King, Barry; King, Matthew; King, Robert Steven Beaufoy; King, Samuel Burton; Kirk, Julie; Kiryunin, Andrey; Kishimoto, Tomoe; Kisielewska, Danuta; Kiss, Florian; Kitamura, Takumi; Kittelmann, Thomas; Kiuchi, Kenji; Kladiva, Eduard; Klein, Max; Klein, Uta; Kleinknecht, Konrad; Klimek, Pawel; Klimentov, Alexei; Klingenberg, Reiner; Klinger, Joel Alexander; Klioutchnikova, Tatiana; Klok, Peter; Kluge, Eike-Erik; Kluit, Peter; Kluth, Stefan; Kneringer, Emmerich; Knoops, Edith; Knue, Andrea; Kobayashi, Tomio; Kobel, Michael; Kocian, Martin; Kodys, Peter; Koevesarki, Peter; Koffas, Thomas; Koffeman, Els; Kogan, Lucy Anne; Kohlmann, Simon; Kohout, Zdenek; Kohriki, Takashi; Koi, Tatsumi; Kolanoski, Hermann; Koletsou, Iro; Koll, James; Komar, Aston; Komori, Yuto; Kondo, Takahiko; Kondrashova, Nataliia; Köneke, Karsten; König, Adriaan; König, Sebastian; Kono, Takanori; Konoplich, Rostislav; Konstantinidis, Nikolaos; Kopeliansky, Revital; Koperny, Stefan; Köpke, Lutz; Kopp, Anna Katharina; Korcyl, Krzysztof; Kordas, Kostantinos; Korn, Andreas; Korol, Aleksandr; Korolkov, Ilya; Korolkova, Elena; Korotkov, Vladislav; Kortner, Oliver; Kortner, Sandra; Kostyukhin, Vadim; Kotov, Sergey; Kotov, Vladislav; Kotwal, Ashutosh; Kourkoumelis, Christine; Kouskoura, Vasiliki; Koutsman, Alex; Kowalewski, Robert Victor; Kowalski, Tadeusz; Kozanecki, Witold; Kozhin, Anatoly; Kral, Vlastimil; Kramarenko, Viktor; Kramberger, Gregor; Krasnopevtsev, Dimitriy; Krasny, Mieczyslaw Witold; Krasznahorkay, Attila; Kraus, Jana; Kravchenko, Anton; Kreiss, Sven; Kretz, Moritz; Kretzschmar, Jan; Kreutzfeldt, Kristof; Krieger, Peter; Kroeninger, Kevin; Kroha, Hubert; Kroll, Joe; Kroseberg, Juergen; Krstic, Jelena; Kruchonak, Uladzimir; Krüger, Hans; Kruker, Tobias; Krumnack, Nils; Krumshteyn, Zinovii; Kruse, Amanda; Kruse, Mark; Kruskal, Michael; Kubik, Petr; Kubota, Takashi; Kuday, Sinan; Kuehn, Susanne; Kugel, Andreas; Kuhl, Andrew; Kuhl, Thorsten; Kukhtin, Victor; Kulchitsky, Yuri; Kuleshov, Sergey; Kuna, Marine; Kunkle, Joshua; Kupco, Alexander; Kurashige, Hisaya; Kurochkin, Yurii; Kurumida, Rie; Kus, Vlastimil; Kuwertz, Emma Sian; Kuze, Masahiro; Kvita, Jiri; La Rosa, Alessandro; La Rotonda, Laura; Lacasta, Carlos; Lacava, Francesco; Lacey, James; Lacker, Heiko; Lacour, Didier; Lacuesta, Vicente Ramón; Ladygin, Evgueni; Lafaye, Remi; Laforge, Bertrand; Lagouri, Theodota; Lai, Stanley; Laier, Heiko; Lambourne, Luke; Lammers, Sabine; Lampen, Caleb; Lampl, Walter; Lançon, Eric; Landgraf, Ulrich; Landon, Murrough; Lang, Valerie Susanne; Lange, Clemens; Lankford, Andrew; Lanni, Francesco; Lantzsch, Kerstin; Laplace, Sandrine; Lapoire, Cecile; Laporte, Jean-Francois; Lari, Tommaso; Lassnig, Mario; Laurelli, Paolo; Lavrijsen, Wim; Law, Alexander; Laycock, Paul; Le, Bao Tran; Le Dortz, Olivier; Le Guirriec, Emmanuel; Le Menedeu, Eve; LeCompte, Thomas; Ledroit-Guillon, Fabienne Agnes Marie; Lee, Claire, Alexandra; Lee, Hurng-Chun; Lee, Jason; Lee, Shih-Chang; Lee, Lawrence; Lefebvre, Guillaume; Lefebvre, Michel; Legger, Federica; Leggett, Charles; Lehan, Allan; Lehmacher, Marc; Lehmann Miotto, Giovanna; Lei, Xiaowen; Leister, Andrew Gerard; Leite, Marco Aurelio Lisboa; Leitner, Rupert; Lellouch, Daniel; Lemmer, Boris; Leney, Katharine; Lenz, Tatjana; Lenzen, Georg; Lenzi, Bruno; Leone, Robert; Leonhardt, Kathrin; Leontsinis, Stefanos; Leroy, Claude; Lester, Christopher; Lester, Christopher Michael; Levchenko, Mikhail; Levêque, Jessica; Levin, Daniel; Levinson, Lorne; Levy, Mark; Lewis, Adrian; Lewis, George; Leyko, Agnieszka; Leyton, Michael; Li, Bing; Li, Bo; Li, Haifeng; Li, Ho Ling; Li, Liang; Li, Shu; Li, Yichen; Liang, Zhijun; Liao, Hongbo; Liberti, Barbara; Lichard, Peter; Lie, Ki; Liebal, Jessica; Liebig, Wolfgang; Limbach, Christian; Limosani, Antonio; Limper, Maaike; Lin, Simon; Linde, Frank; Lindquist, Brian Edward; Linnemann, James; Lipeles, Elliot; Lipniacka, Anna; Lisovyi, Mykhailo; Liss, Tony; Lissauer, David; Lister, Alison; Litke, Alan; Liu, Bo; Liu, Dong; Liu, Jianbei; Liu, Kun; Liu, Lulu; Liu, Miaoyuan; Liu, Minghui; Liu, Yanwen; Livan, Michele; Livermore, Sarah; Lleres, Annick; Llorente Merino, Javier; Lloyd, Stephen; Lo Sterzo, Francesco; Lobodzinska, Ewelina; Loch, Peter; Lockman, William; Loddenkoetter, Thomas; Loebinger, Fred; Loevschall-Jensen, Ask Emil; Loginov, Andrey; Loh, Chang Wei; Lohse, Thomas; Lohwasser, Kristin; Lokajicek, Milos; Lombardo, Vincenzo Paolo; Long, Brian Alexander; Long, Jonathan; Long, Robin Eamonn; Lopes, Lourenco; Lopez Mateos, David; Lopez Paredes, Brais; Lorenz, Jeanette; Lorenzo Martinez, Narei; Losada, Marta; Loscutoff, Peter; Lou, XinChou; Lounis, Abdenour; Love, Jeremy; Love, Peter; Lowe, Andrew; Lu, Feng; Lubatti, Henry; Luci, Claudio; Lucotte, Arnaud; Luehring, Frederick; Lukas, Wolfgang; Luminari, Lamberto; Lundberg, Olof; Lund-Jensen, Bengt; Lungwitz, Matthias; Lynn, David; Lysak, Roman; Lytken, Else; Ma, Hong; Ma, Lian Liang; Maccarrone, Giovanni; Macchiolo, Anna; Machado Miguens, Joana; Macina, Daniela; Madaffari, Daniele; Madar, Romain; Maddocks, Harvey Jonathan; Mader, Wolfgang; Madsen, Alexander; Maeno, Mayuko; Maeno, Tadashi; Magradze, Erekle; Mahboubi, Kambiz; Mahlstedt, Joern; Mahmoud, Sara; Maiani, Camilla; Maidantchik, Carmen; Maio, Amélia; Majewski, Stephanie; Makida, Yasuhiro; Makovec, Nikola; Mal, Prolay; Malaescu, Bogdan; Malecki, Pawel; Maleev, Victor; Malek, Fairouz; Mallik, Usha; Malon, David; Malone, Caitlin; Maltezos, Stavros; Malyshev, Vladimir; Malyukov, Sergei; Mamuzic, Judita; Mandelli, Beatrice; Mandelli, Luciano; Mandić, Igor; Mandrysch, Rocco; Maneira, José; Manfredini, Alessandro; Manhaes de Andrade Filho, Luciano; Manjarres Ramos, Joany Andreina; Mann, Alexander; Manning, Peter; Manousakis-Katsikakis, Arkadios; Mansoulie, Bruno; Mantifel, Rodger; Mapelli, Livio; March, Luis; Marchand, Jean-Francois; Marchiori, Giovanni; Marcisovsky, Michal; Marino, Christopher; Marques, Carlos; Marroquim, Fernando; Marsden, Stephen Philip; Marshall, Zach; Marti, Lukas Fritz; Marti-Garcia, Salvador; Martin, Brian; Martin, Brian; Martin, Jean-Pierre; Martin, Tim; Martin, Victoria Jane; Martin dit Latour, Bertrand; Martinez, Homero; Martinez, Mario; Martin-Haugh, Stewart; Martyniuk, Alex; Marx, Marilyn; Marzano, Francesco; Marzin, Antoine; Masetti, Lucia; Mashimo, Tetsuro; Mashinistov, Ruslan; Masik, Jiri; Maslennikov, Alexey; Massa, Ignazio; Massol, Nicolas; Mastrandrea, Paolo; Mastroberardino, Anna; Masubuchi, Tatsuya; Matricon, Pierre; Matsunaga, Hiroyuki; Matsushita, Takashi; Mättig, Peter; Mättig, Stefan; Mattmann, Johannes; Maurer, Julien; Maxfield, Stephen; Maximov, Dmitriy; Mazini, Rachid; Mazzaferro, Luca; Mc Goldrick, Garrin; Mc Kee, Shawn Patrick; McCarn, Allison; McCarthy, Robert; McCarthy, Tom; McCubbin, Norman; McFarlane, Kenneth; Mcfayden, Josh; Mchedlidze, Gvantsa; Mclaughlan, Tom; McMahon, Steve; McPherson, Robert; Meade, Andrew; Mechnich, Joerg; Medinnis, Michael; Meehan, Samuel; Mehlhase, Sascha; Mehta, Andrew; Meier, Karlheinz; Meineck, Christian; Meirose, Bernhard; Melachrinos, Constantinos; Mellado Garcia, Bruce Rafael; Meloni, Federico; Mengarelli, Alberto; Menke, Sven; Meoni, Evelin; Mercurio, Kevin Michael; Mergelmeyer, Sebastian; Meric, Nicolas; Mermod, Philippe; Merola, Leonardo; Meroni, Chiara; Merritt, Frank; Merritt, Hayes; Messina, Andrea; Metcalfe, Jessica; Mete, Alaettin Serhan; Meyer, Carsten; Meyer, Christopher; Meyer, Jean-Pierre; Meyer, Jochen; Middleton, Robin; Migas, Sylwia; Mijović, Liza; Mikenberg, Giora; Mikestikova, Marcela; Mikuž, Marko; Miller, David; Mills, Corrinne; Milov, Alexander; Milstead, David; Milstein, Dmitry; Minaenko, Andrey; Miñano Moya, Mercedes; Minashvili, Irakli; Mincer, Allen; Mindur, Bartosz; Mineev, Mikhail; Ming, Yao; Mir, Lluisa-Maria; Mirabelli, Giovanni; Mitani, Takashi; Mitrevski, Jovan; Mitsou, Vasiliki A; Mitsui, Shingo; Miucci, Antonio; Miyagawa, Paul; Mjörnmark, Jan-Ulf; Moa, Torbjoern; Mochizuki, Kazuya; Moeller, Victoria; Mohapatra, Soumya; Mohr, Wolfgang; Molander, Simon; Moles-Valls, Regina; Mönig, Klaus; Monini, Caterina; Monk, James; Monnier, Emmanuel; Montejo Berlingen, Javier; Monticelli, Fernando; Monzani, Simone; Moore, Roger; Moraes, Arthur; Morange, Nicolas; Morel, Julien; Moreno, Deywis; Moreno Llácer, María; Morettini, Paolo; Morgenstern, Marcus; Morii, Masahiro; Moritz, Sebastian; Morley, Anthony Keith; Mornacchi, Giuseppe; Morris, John; Morvaj, Ljiljana; Moser, Hans-Guenther; Mosidze, Maia; Moss, Josh; Mount, Richard; Mountricha, Eleni; Mouraviev, Sergei; Moyse, Edward; Muanza, Steve; Mudd, Richard; Mueller, Felix; Mueller, James; Mueller, Klemens; Mueller, Thibaut; Mueller, Timo; Muenstermann, Daniel; Munwes, Yonathan; Murillo Quijada, Javier Alberto; Murray, Bill; Musheghyan, Haykuhi; Musto, Elisa; Myagkov, Alexey; Myska, Miroslav; Nackenhorst, Olaf; Nadal, Jordi; Nagai, Koichi; Nagai, Ryo; Nagai, Yoshikazu; Nagano, Kunihiro; Nagarkar, Advait; Nagasaka, Yasushi; Nagel, Martin; Nairz, Armin Michael; Nakahama, Yu; Nakamura, Koji; Nakamura, Tomoaki; Nakano, Itsuo; Namasivayam, Harisankar; Nanava, Gizo; Narayan, Rohin; Nattermann, Till; Naumann, Thomas; Navarro, Gabriela; Nayyar, Ruchika; Neal, Homer; Nechaeva, Polina; Neep, Thomas James; Negri, Andrea; Negri, Guido; Negrini, Matteo; Nektarijevic, Snezana; Nelson, Andrew; Nelson, Timothy Knight; Nemecek, Stanislav; Nemethy, Peter; Nepomuceno, Andre Asevedo; Nessi, Marzio; Neubauer, Mark; Neumann, Manuel; Neves, Ricardo; Nevski, Pavel; Newcomer, Mitchel; Newman, Paul; Nguyen, Duong Hai; Nickerson, Richard; Nicolaidou, Rosy; Nicquevert, Bertrand; Nielsen, Jason; Nikiforou, Nikiforos; Nikiforov, Andriy; Nikolaenko, Vladimir; Nikolic-Audit, Irena; Nikolics, Katalin; Nikolopoulos, Konstantinos; Nilsson, Paul; Ninomiya, Yoichi; Nisati, Aleandro; Nisius, Richard; Nobe, Takuya; Nodulman, Lawrence; Nomachi, Masaharu; Nomidis, Ioannis; Norberg, Scarlet; Nordberg, Markus; Nowak, Sebastian; Nozaki, Mitsuaki; Nozka, Libor; Ntekas, Konstantinos; Nunes Hanninger, Guilherme; Nunnemann, Thomas; Nurse, Emily; Nuti, Francesco; O'Brien, Brendan Joseph; O'grady, Fionnbarr; O'Neil, Dugan; O'Shea, Val; Oakham, Gerald; Oberlack, Horst; Obermann, Theresa; Ocariz, Jose; Ochi, Atsuhiko; Ochoa, Ines; Oda, Susumu; Odaka, Shigeru; Ogren, Harold; Oh, Alexander; Oh, Seog; Ohm, Christian; Ohman, Henrik; Ohshima, Takayoshi; Okamura, Wataru; Okawa, Hideki; Okumura, Yasuyuki; Okuyama, Toyonobu; Olariu, Albert; Olchevski, Alexander; Olivares Pino, Sebastian Andres; Oliveira Damazio, Denis; Oliver Garcia, Elena; Olszewski, Andrzej; Olszowska, Jolanta; Onofre, António; Onyisi, Peter; Oram, Christopher; Oreglia, Mark; Oren, Yona; Orestano, Domizia; Orlando, Nicola; Oropeza Barrera, Cristina; Orr, Robert; Osculati, Bianca; Ospanov, Rustem; Otero y Garzon, Gustavo; Otono, Hidetoshi; Ouchrif, Mohamed; Ouellette, Eric; Ould-Saada, Farid; Ouraou, Ahmimed; Oussoren, Koen Pieter; Ouyang, Qun; Ovcharova, Ana; Owen, Mark; Ozcan, Veysi Erkcan; Ozturk, Nurcan; Pachal, Katherine; Pacheco Pages, Andres; Padilla Aranda, Cristobal; Pagáčová, Martina; Pagan Griso, Simone; Paganis, Efstathios; Pahl, Christoph; Paige, Frank; Pais, Preema; Pajchel, Katarina; Palacino, Gabriel; Palestini, Sandro; Pallin, Dominique; Palma, Alberto; Palmer, Jody; Pan, Yibin; Panagiotopoulou, Evgenia; Panduro Vazquez, William; Pani, Priscilla; Panikashvili, Natalia; Panitkin, Sergey; Pantea, Dan; Paolozzi, Lorenzo; Papadopoulou, Theodora; Papageorgiou, Konstantinos; Paramonov, Alexander; Paredes Hernandez, Daniela; Parker, Michael Andrew; Parodi, Fabrizio; Parsons, John; Parzefall, Ulrich; Pasqualucci, Enrico; Passaggio, Stefano; Passeri, Antonio; Pastore, Fernanda; Pastore, Francesca; Pásztor, Gabriella; Pataraia, Sophio; Patel, Nikhul; Pater, Joleen; Patricelli, Sergio; Pauly, Thilo; Pearce, James; Pedersen, Maiken; Pedraza Lopez, Sebastian; Pedro, Rute; Peleganchuk, Sergey; Pelikan, Daniel; Peng, Haiping; Penning, Bjoern; Penwell, John; Perepelitsa, Dennis; Perez Codina, Estel; Pérez García-Estañ, María Teresa; Perez Reale, Valeria; Perini, Laura; Pernegger, Heinz; Perrino, Roberto; Peschke, Richard; Peshekhonov, Vladimir; Peters, Krisztian; Peters, Yvonne; Petersen, Brian; Petersen, Jorgen; Petersen, Troels; Petit, Elisabeth; Petridis, Andreas; Petridou, Chariclia; Petrolo, Emilio; Petrucci, Fabrizio; Petteni, Michele; Pettersson, Nora Emilia; Pezoa, Raquel; Phillips, Peter William; Piacquadio, Giacinto; Pianori, Elisabetta; Picazio, Attilio; Piccaro, Elisa; Piccinini, Maurizio; Piegaia, Ricardo; Pieron, Jacek Piotr; Pignotti, David; Pilcher, James; Pilkington, Andrew; Pina, João Antonio; Pinamonti, Michele; Pinder, Alex; Pinfold, James; Pingel, Almut; Pinto, Belmiro; Pires, Sylvestre; Pitt, Michael; Pizio, Caterina; Pleier, Marc-Andre; Pleskot, Vojtech; Plotnikova, Elena; Plucinski, Pawel; Poddar, Sahill; Podlyski, Fabrice; Poettgen, Ruth; Poggioli, Luc; Pohl, David-leon; Pohl, Martin; Polesello, Giacomo; Policicchio, Antonio; Polifka, Richard; Polini, Alessandro; Pollard, Christopher Samuel; Polychronakos, Venetios; Pommès, Kathy; Pontecorvo, Ludovico; Pope, Bernard; Popeneciu, Gabriel Alexandru; Popovic, Dragan; Poppleton, Alan; Portell Bueso, Xavier; Pospelov, Guennady; Pospisil, Stanislav; Potamianos, Karolos; Potrap, Igor; Potter, Christina; Potter, Christopher; Poulard, Gilbert; Poveda, Joaquin; Pozdnyakov, Valery; Pralavorio, Pascal; Pranko, Aliaksandr; Prasad, Srivas; Pravahan, Rishiraj; Prell, Soeren; Price, Darren; Price, Joe; Price, Lawrence; Prieur, Damien; Primavera, Margherita; Proissl, Manuel; Prokofiev, Kirill; Prokoshin, Fedor; Protopapadaki, Eftychia-sofia; Protopopescu, Serban; Proudfoot, James; Przybycien, Mariusz; Przysiezniak, Helenka; Ptacek, Elizabeth; Pueschel, Elisa; Puldon, David; Purohit, Milind; Puzo, Patrick; Qian, Jianming; Qin, Gang; Qin, Yang; Quadt, Arnulf; Quarrie, David; Quayle, William; Quilty, Donnchadha; Qureshi, Anum; Radeka, Veljko; Radescu, Voica; Radhakrishnan, Sooraj Krishnan; Radloff, Peter; Rados, Pere; Ragusa, Francesco; Rahal, Ghita; Rajagopalan, Srinivasan; Rammensee, Michael; Randle-Conde, Aidan Sean; Rangel-Smith, Camila; Rao, Kanury; Rauscher, Felix; Rave, Tobias Christian; Ravenscroft, Thomas; Raymond, Michel; Read, Alexander Lincoln; Rebuzzi, Daniela; Redelbach, Andreas; Redlinger, George; Reece, Ryan; Reeves, Kendall; Rehnisch, Laura; Reinsch, Andreas; Reisin, Hernan; Relich, Matthew; Rembser, Christoph; Ren, Zhongliang; Renaud, Adrien; Rescigno, Marco; Resconi, Silvia; Resende, Bernardo; Rezanova, Olga; Reznicek, Pavel; Rezvani, Reyhaneh; Richter, Robert; Ridel, Melissa; Rieck, Patrick; Rijssenbeek, Michael; Rimoldi, Adele; Rinaldi, Lorenzo; Ritsch, Elmar; Riu, Imma; Rizatdinova, Flera; Rizvi, Eram; Robertson, Steven; Robichaud-Veronneau, Andree; Robinson, Dave; Robinson, James; Robson, Aidan; Roda, Chiara; Rodrigues, Luis; Roe, Shaun; Røhne, Ole; Rolli, Simona; Romaniouk, Anatoli; Romano, Marino; Romeo, Gaston; Romero Adam, Elena; Rompotis, Nikolaos; Roos, Lydia; Ros, Eduardo; Rosati, Stefano; Rosbach, Kilian; Rose, Matthew; Rosendahl, Peter Lundgaard; Rosenthal, Oliver; Rossetti, Valerio; Rossi, Elvira; Rossi, Leonardo Paolo; Rosten, Rachel; Rotaru, Marina; Roth, Itamar; Rothberg, Joseph; Rousseau, David; Royon, Christophe; Rozanov, Alexandre; Rozen, Yoram; Ruan, Xifeng; Rubbo, Francesco; Rubinskiy, Igor; Rud, Viacheslav; Rudolph, Christian; Rudolph, Matthew Scott; Rühr, Frederik; Ruiz-Martinez, Aranzazu; Rurikova, Zuzana; Rusakovich, Nikolai; Ruschke, Alexander; Rutherfoord, John; Ruthmann, Nils; Ryabov, Yury; Rybar, Martin; Rybkin, Grigori; Ryder, Nick; Saavedra, Aldo; Sacerdoti, Sabrina; Saddique, Asif; Sadeh, Iftach; Sadrozinski, Hartmut; Sadykov, Renat; Safai Tehrani, Francesco; Sakamoto, Hiroshi; Sakurai, Yuki; Salamanna, Giuseppe; Salamon, Andrea; Saleem, Muhammad; Salek, David; Sales De Bruin, Pedro Henrique; Salihagic, Denis; Salnikov, Andrei; Salt, José; Salvachua Ferrando, Belén; Salvatore, Daniela; Salvatore, Pasquale Fabrizio; Salvucci, Antonio; Salzburger, Andreas; Sampsonidis, Dimitrios; Sanchez, Arturo; Sánchez, Javier; Sanchez Martinez, Victoria; Sandaker, Heidi; Sandbach, Ruth Laura; Sander, Heinz Georg; Sanders, Michiel; Sandhoff, Marisa; Sandoval, Tanya; Sandoval, Carlos; Sandstroem, Rikard; Sankey, Dave; Sansoni, Andrea; Santoni, Claudio; Santonico, Rinaldo; Santos, Helena; Santoyo Castillo, Itzebelt; Sapp, Kevin; Sapronov, Andrey; Saraiva, João; Sarrazin, Bjorn; Sartisohn, Georg; Sasaki, Osamu; Sasaki, Yuichi; Satsounkevitch, Igor; Sauvage, Gilles; Sauvan, Emmanuel; Savard, Pierre; Savu, Dan Octavian; Sawyer, Craig; Sawyer, Lee; Saxon, James; Sbarra, Carla; Sbrizzi, Antonio; Scanlon, Tim; Scannicchio, Diana; Scarcella, Mark; Schaarschmidt, Jana; Schacht, Peter; Schaefer, Douglas; Schaefer, Ralph; Schaepe, Steffen; Schaetzel, Sebastian; Schäfer, Uli; Schaffer, Arthur; Schaile, Dorothee; Schamberger, R. Dean; Scharf, Veit; Schegelsky, Valery; Scheirich, Daniel; Schernau, Michael; Scherzer, Max; Schiavi, Carlo; Schieck, Jochen; Schillo, Christian; Schioppa, Marco; Schlenker, Stefan; Schmidt, Evelyn; Schmieden, Kristof; Schmitt, Christian; Schmitt, Christopher; Schmitt, Sebastian; Schneider, Basil; Schnellbach, Yan Jie; Schnoor, Ulrike; Schoeffel, Laurent; Schoening, Andre; Schoenrock, Bradley Daniel; Schorlemmer, Andre Lukas; Schott, Matthias; Schouten, Doug; Schovancova, Jaroslava; Schram, Malachi; Schramm, Steven; Schreyer, Manuel; Schroeder, Christian; Schuh, Natascha; Schultens, Martin Johannes; Schultz-Coulon, Hans-Christian; Schulz, Holger; Schumacher, Markus; Schumm, Bruce; Schune, Philippe; Schwartzman, Ariel; Schwegler, Philipp; Schwemling, Philippe; Schwienhorst, Reinhard; Schwindling, Jerome; Schwindt, Thomas; Schwoerer, Maud; Sciacca, Gianfranco; Scifo, Estelle; Sciolla, Gabriella; Scott, Bill; Scuri, Fabrizio; Scutti, Federico; Searcy, Jacob; Sedov, George; Sedykh, Evgeny; 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Spreitzer, Teresa; Spurlock, Barry; St Denis, Richard Dante; Staerz, Steffen; Stahlman, Jonathan; Stamen, Rainer; Stanecka, Ewa; Stanek, Robert; Stanescu, Cristian; Stanescu-Bellu, Madalina; Stanitzki, Marcel Michael; Stapnes, Steinar; Starchenko, Evgeny; Stark, Jan; Staroba, Pavel; Starovoitov, Pavel; Staszewski, Rafal; Stavina, Pavel; Steele, Genevieve; Steinberg, Peter; Stekl, Ivan; Stelzer, Bernd; Stelzer, Harald Joerg; Stelzer-Chilton, Oliver; Stenzel, Hasko; Stern, Sebastian; Stewart, Graeme; Stillings, Jan Andre; Stockton, Mark; Stoebe, Michael; Stoicea, Gabriel; Stolte, Philipp; Stonjek, Stefan; Stradling, Alden; Straessner, Arno; Stramaglia, Maria Elena; Strandberg, Jonas; Strandberg, Sara; Strandlie, Are; Strauss, Emanuel; Strauss, Michael; Strizenec, Pavol; Ströhmer, Raimund; Strom, David; Stroynowski, Ryszard; Stucci, Stefania Antonia; Stugu, Bjarne; Styles, Nicholas Adam; Su, Dong; Su, Jun; Subramania, Halasya Siva; Subramaniam, Rajivalochan; Succurro, Antonella; Sugaya, Yorihito; Suhr, Chad; Suk, Michal; Sulin, Vladimir; Sultansoy, Saleh; Sumida, Toshi; Sun, Xiaohu; Sundermann, Jan Erik; Suruliz, Kerim; Susinno, Giancarlo; Sutton, Mark; Suzuki, Yu; Svatos, Michal; Swedish, Stephen; Swiatlowski, Maximilian; Sykora, Ivan; Sykora, Tomas; Ta, Duc; Tackmann, Kerstin; Taenzer, Joe; Taffard, Anyes; Tafirout, Reda; Taiblum, Nimrod; Takahashi, Yuta; Takai, Helio; Takashima, Ryuichi; Takeda, Hiroshi; Takeshita, Tohru; Takubo, Yosuke; Talby, Mossadek; Talyshev, Alexey; Tam, Jason; Tamsett, Matthew; Tan, Kong Guan; Tanaka, Junichi; Tanaka, Reisaburo; Tanaka, Satoshi; Tanaka, Shuji; Tanasijczuk, Andres Jorge; Tani, Kazutoshi; Tannoury, Nancy; Tapprogge, Stefan; Tarem, Shlomit; Tarrade, Fabien; Tartarelli, Giuseppe Francesco; Tas, Petr; Tasevsky, Marek; Tashiro, Takuya; Tassi, Enrico; Tavares Delgado, Ademar; Tayalati, Yahya; Taylor, Frank; Taylor, Geoffrey; Taylor, Wendy; Teischinger, Florian Alfred; Teixeira Dias Castanheira, Matilde; Teixeira-Dias, Pedro; Temming, Kim Katrin; Ten Kate, Herman; Teng, Ping-Kun; Terada, Susumu; Terashi, Koji; Terron, Juan; Terzo, Stefano; Testa, Marianna; Teuscher, Richard; Therhaag, Jan; Theveneaux-Pelzer, Timothée; Thoma, Sascha; Thomas, Juergen; Thomas-Wilsker, Joshuha; Thompson, Emily; Thompson, Paul; Thompson, Peter; Thompson, Stan; Thomsen, Lotte Ansgaard; Thomson, Evelyn; Thomson, Mark; Thong, Wai Meng; Thun, Rudolf; Tian, Feng; Tibbetts, Mark James; Tikhomirov, Vladimir; Tikhonov, Yury; Timoshenko, Sergey; Tiouchichine, Elodie; Tipton, Paul; Tisserant, Sylvain; Todorov, Theodore; Todorova-Nova, Sharka; Toggerson, Brokk; Tojo, Junji; Tokár, Stanislav; Tokushuku, Katsuo; Tollefson, Kirsten; Tomlinson, Lee; Tomoto, Makoto; Tompkins, Lauren; Toms, Konstantin; Topilin, Nikolai; Torrence, Eric; Torres, Heberth; Torró Pastor, Emma; Toth, Jozsef; Touchard, Francois; Tovey, Daniel; Tran, Huong Lan; Trefzger, Thomas; Tremblet, Louis; Tricoli, Alessandro; Trigger, Isabel Marian; Trincaz-Duvoid, Sophie; Tripiana, Martin; Triplett, Nathan; Trischuk, William; Trocmé, Benjamin; Troncon, Clara; Trottier-McDonald, Michel; Trovatelli, Monica; True, Patrick; Trzebinski, Maciej; Trzupek, Adam; Tsarouchas, Charilaos; Tseng, Jeffrey; Tsiareshka, Pavel; Tsionou, Dimitra; Tsipolitis, Georgios; Tsirintanis, Nikolaos; Tsiskaridze, Shota; Tsiskaridze, Vakhtang; Tskhadadze, Edisher; Tsukerman, Ilya; Tsulaia, Vakhtang; Tsuno, Soshi; Tsybychev, Dmitri; Tudorache, Alexandra; Tudorache, Valentina; Tuna, Alexander Naip; Tupputi, Salvatore; Turchikhin, Semen; Turecek, Daniel; Turk Cakir, Ilkay; Turra, Ruggero; Tuts, Michael; Tykhonov, Andrii; Tylmad, Maja; Tyndel, Mike; Uchida, Kirika; Ueda, Ikuo; Ueno, Ryuichi; Ughetto, Michael; Ugland, Maren; Uhlenbrock, Mathias; Ukegawa, Fumihiko; Unal, Guillaume; Undrus, Alexander; Unel, Gokhan; Ungaro, Francesca; Unno, Yoshinobu; Urbaniec, Dustin; Urquijo, Phillip; Usai, Giulio; Usanova, Anna; Vacavant, Laurent; Vacek, Vaclav; Vachon, Brigitte; Valencic, Nika; Valentinetti, Sara; Valero, Alberto; Valery, Loic; 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Watanabe, Ippei; Watkins, Peter; Watson, Alan; Watson, Ian; Watson, Miriam; Watts, Gordon; Watts, Stephen; Waugh, Ben; Webb, Samuel; Weber, Michele; Weber, Stefan Wolf; Webster, Jordan S; Weidberg, Anthony; Weigell, Philipp; Weinert, Benjamin; Weingarten, Jens; Weiser, Christian; Weits, Hartger; Wells, Phillippa; Wenaus, Torre; Wendland, Dennis; Weng, Zhili; Wengler, Thorsten; Wenig, Siegfried; Wermes, Norbert; Werner, Matthias; Werner, Per; Wessels, Martin; Wetter, Jeffrey; Whalen, Kathleen; White, Andrew; White, Martin; White, Ryan; White, Sebastian; Whiteson, Daniel; Wicke, Daniel; Wickens, Fred; Wiedenmann, Werner; Wielers, Monika; Wienemann, Peter; Wiglesworth, Craig; Wiik-Fuchs, Liv Antje Mari; Wijeratne, Peter Alexander; Wildauer, Andreas; Wildt, Martin Andre; Wilkens, Henric George; Will, Jonas Zacharias; Williams, Hugh; Williams, Sarah; Willis, Christopher; Willocq, Stephane; Wilson, John; Wilson, Alan; Wingerter-Seez, Isabelle; Winklmeier, Frank; Wittgen, Matthias; Wittig, Tobias; Wittkowski, Josephine; Wollstadt, Simon Jakob; Wolter, Marcin Wladyslaw; Wolters, Helmut; Wosiek, Barbara; Wotschack, Jorg; Woudstra, Martin; Wozniak, Krzysztof; Wright, Michael; Wu, Mengqing; Wu, Sau Lan; Wu, Xin; Wu, Yusheng; Wulf, Evan; Wyatt, Terry Richard; Wynne, Benjamin; Xella, Stefania; Xiao, Meng; Xu, Da; Xu, Lailin; Yabsley, Bruce; Yacoob, Sahal; Yamada, Miho; Yamaguchi, Hiroshi; Yamaguchi, Yohei; Yamamoto, Akira; Yamamoto, Kyoko; Yamamoto, Shimpei; Yamamura, Taiki; Yamanaka, Takashi; Yamauchi, Katsuya; Yamazaki, Yuji; Yan, Zhen; Yang, Haijun; Yang, Hongtao; Yang, Un-Ki; Yang, Yi; Yanush, Serguei; Yao, Liwen; Yao, Weiming; Yasu, Yoshiji; Yatsenko, Elena; Yau Wong, Kaven Henry; Ye, Jingbo; Ye, Shuwei; Yen, Andy L; Yildirim, Eda; Yilmaz, Metin; Yoosoofmiya, Reza; Yorita, Kohei; Yoshida, Rikutaro; Yoshihara, Keisuke; Young, Charles; Young, Christopher John; Youssef, Saul; Yu, David Ren-Hwa; Yu, Jaehoon; Yu, Jiaming; Yu, Jie; Yuan, Li; Yurkewicz, Adam; Zabinski, Bartlomiej; Zaidan, Remi; Zaitsev, Alexander; Zaman, Aungshuman; Zambito, Stefano; Zanello, Lucia; Zanzi, Daniele; Zaytsev, Alexander; Zeitnitz, Christian; Zeman, Martin; Zemla, Andrzej; Zengel, Keith; Zenin, Oleg; Ženiš, Tibor; Zerwas, Dirk; Zevi della Porta, Giovanni; Zhang, Dongliang; Zhang, Fangzhou; Zhang, Huaqiao; Zhang, Jinlong; Zhang, Lei; Zhang, Xueyao; Zhang, Zhiqing; Zhao, Zhengguo; Zhemchugov, Alexey; Zhong, Jiahang; Zhou, Bing; Zhou, Lei; Zhou, Ning; Zhu, Cheng Guang; Zhu, Hongbo; Zhu, Junjie; Zhu, Yingchun; Zhuang, Xuai; Zibell, Andre; Zieminska, Daria; Zimine, Nikolai; Zimmermann, Christoph; Zimmermann, Robert; Zimmermann, Simone; Zimmermann, Stephanie; Zinonos, Zinonas; Ziolkowski, Michael; Zobernig, Georg; Zoccoli, Antonio; zur Nedden, Martin; Zurzolo, Giovanni; Zutshi, Vishnu; Zwalinski, Lukasz

    2014-01-01

    The semiconductor tracker is a silicon microstrip detector forming part of the inner tracking system of the ATLAS experiment at the LHC. The operation and performance of the semiconductor tracker during the first years of LHC running are described. More than 99% of the detector modules were operational during this period, with an average intrinsic hit efficiency of (99.74 +/- 0.04)%. The evolution of the noise occupancy is discussed, and measurements of the Lorentz angle, delta-ray production and energy loss presented. The alignment of the detector is found to be stable at the few-micron level over long periods of time. Radiation damage measurements, which include the evolution of detector leakage currents, are found to be consistent with predictions and are used in the verification of radiation background simulations.

  8. Semiconductor bridge (SCB) detonator

    Science.gov (United States)

    Bickes, Jr., Robert W.; Grubelich, Mark C.

    1999-01-01

    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length.

  9. 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...

  10. Imaging performance of the hybrid pixel detectors XPAD3-S.

    Science.gov (United States)

    Brunner, F Cassol; Clemens, J C; Hemmer, C; Morel, C

    2009-03-21

    Hybrid pixel detectors, originally developed for tracking particles in high-energy physics experiments, have recently been used in material sciences and macromolecular crystallography. Their capability to count single photons and to apply a threshold on the photon energy suggests that they could be optimal digital x-ray detectors in low energy beams such as for small animal computed tomography (CT). To investigate this issue, we have studied the imaging performance of photon counting hybrid pixel detectors based on the XPAD3-S chip. Two detectors are considered, connected either to a Si or to a CdTe sensor, the latter being of interest for its higher efficiency. Both a standard 'International Electrotechnical Commission' (IEC) mammography beam and a beam used for mouse CT results published in the literature are employed. The detector stability, linearity and noise are investigated as a function of the dose for several imaging exposures ( approximately 0.1-400 microGy). The perfect linearity of both detectors is confirmed, but an increase in internal noise for counting statistics higher than approximately 5000 photons has been found, corresponding to exposures above approximately 110 microGy and approximately 50 microGy for the Si and CdTe sensors, respectively. The noise power spectrum (NPS), the modulation transfer function (MTF) and the detective quantum efficiency (DQE) are then measured for two energy threshold configurations (5 keV and 18 keV) and three doses ( approximately 3, 30 and 300 microGy), in order to obtain a complete estimation of the detector performances. In general, the CdTe sensor shows a clear superiority with a maximal DQE(0) of approximately 1, thanks to its high efficiency ( approximately 100%). The DQE of the Si sensor is more dependent on the radiation quality, due to the energy dependence of its efficiency its maximum is approximately 0.4 with respect to the softer radiation. Finally, we compare the XPAD3-S DQE with published curves of

  11. Degradation and capacitance: voltage hysteresis in CdTe devices

    Science.gov (United States)

    Albin, D. S.; Dhere, R. G.; Glynn, S. C.; del Cueto, J. A.; Metzger, W. K.

    2009-08-01

    CdS/CdTe photovoltaic solar cells were made on two different transparent conducting oxide (TCO) structures in order to identify differences in fabrication, performance, and reliability. In one set of cells, chemical vapor deposition (CVD) was used to deposit a bi-layer TCO on Corning 7059 borosilicate glass consisting of a F-doped, conductive tin-oxide (cSnO2) layer capped by an insulating (undoped), buffer (iSnO2) layer. In the other set, a more advanced bi-layer structure consisting of sputtered cadmium stannate (Cd2SnO4; CTO) as the conducting layer and zinc stannate (Zn2SnO4; ZTO) as the buffer layer was used. CTO/ZTO substrates yielded higher performance devices however performance uniformity was worse due to possible strain effects associated with TCO layer fabrication. Cells using the SnO2-based structure were only slightly lower in performance, but exhibited considerably greater performance uniformity. When subjected to accelerated lifetime testing (ALT) at 85 - 100 °C under 1-sun illumination and open-circuit bias, more degradation was observed in CdTe cells deposited on the CTO/ZTO substrates. Considerable C-V hysteresis, defined as the depletion width difference between reverse and forward direction scans, was observed in all Cu-doped CdTe cells. These same effects can also be observed in thin-film modules. Hysteresis was observed to increase with increasing stress and degradation. The mechanism for hysteresis is discussed in terms of both an ionic-drift model and one involving majority carrier emission in the space-charge region (SCR). The increased generation of hysteresis observed in CdTe cells deposited on CTO/ZTO substrates suggests potential decomposition of these latter oxides when subjected to stress testing.

  12. The strange diffusivity of Ag atoms in CdTe

    CERN Document Server

    Wolf, H; Ostheimer, V; Schachtrup, A R; Stolwijk, N A; Wichert, T

    2001-01-01

    The diffusion of Ag atoms in CdTe was investigated using the radiotracer $^{111}\\!$Ag, which was introduced by implantation with an energy of 60 or 80 keV. The measured diffusion profiles are explained by assuming the existence of a repulsive interaction between Ag and residual Cu atoms causing a drift of the Ag atoms towards the centre of the crystal, which supposes the diffusion in a concentration gradient. This effect vanishes if the Ag concentration is increased and becomes more pronounced if the crystals are simultaneously co- doped with Cu. (11 refs).