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Sample records for cdte semiconductor detector

  1. Prototype of high resolution PET using resistive electrode position sensitive CdTe detectors

    International Nuclear Information System (INIS)

    Kikuchi, Yohei; Ishii, Keizo; Matsuyama, Shigeo; Yamazaki, Hiromichi

    2008-01-01

    Downsizing detector elements makes it possible that spatial resolutions of positron emission tomography (PET) cameras are improved very much. From this point of view, semiconductor detectors are preferable. To obtain high resolution, the pixel type or the multi strip type of semiconductor detectors can be used. However, in this case, there is a low packing ratio problem, because a dead area between detector arrays cannot be neglected. Here, we propose the use of position sensitive semiconductor detectors with resistive electrode. The CdTe detector is promising as a detector for PET camera because of its high sensitivity. In this paper, we report development of prototype of high resolution PET using resistive electrode position sensitive CdTe detectors. We made 1-dimensional position sensitive CdTe detectors experimentally by changing the electrode thickness. We obtained 750 A as an appropriate thickness of position sensitive detectors, and evaluated the performance of the detector using a collimated 241 Am source. A good position resolution of 1.2 mm full width half maximum (FWHM) was obtained. On the basis of the fundamental development of resistive electrode position sensitive detectors, we constructed a prototype of high resolution PET which was a dual head type and was consisted of thirty-two 1-dimensional position sensitive detectors. In conclusion, we obtained high resolutions which are 0.75 mm (FWHM) in transaxial, and 1.5 mm (FWHM) in axial. (author)

  2. A stacked CdTe pixel detector for a compton camera

    International Nuclear Information System (INIS)

    Oonuki, Kousuke; Tanaka, Takaaki; Watanabe, Shin; Takeda, Shin'ichiro; Nakazawa, Kazuhiro; Ushio, Masayoshi; Mitani, Takefumi; Takahashi, Tadayuki; Tajima, Hiroyasu

    2007-01-01

    We are developing a semiconductor Compton telescope to explore the universe in the energy band from several tens of keV to a few MeV. A detector material of combined Si strip and CdTe pixel is used to cover the energy range around 60keV. For energies above several hundred keV, in contrast, the higher detection efficiency of CdTe semiconductor in comparison with Si is expected to play an important role as both an absorber and a scatterer. In order to demonstrate the spectral and imaging capability of a CdTe-based Compton camera, we developed a Compton telescope consisting of a stack of CdTe pixel detectors as a small scale prototype. With this prototype, we succeeded in reconstructing images and spectra by solving the Compton kinematics within the energy band from 122 to 662keV. The energy resolution (FWHM) of reconstructed spectra is 7.3keV at 511keV. The angular resolution obtained at 511keV is measured to be 12.2 deg. (FWHM)

  3. Advanced processing of CdTe pixel radiation detectors

    Science.gov (United States)

    Gädda, A.; Winkler, A.; Ott, J.; Härkönen, J.; Karadzhinova-Ferrer, A.; Koponen, P.; Luukka, P.; Tikkanen, J.; Vähänen, S.

    2017-12-01

    We report a fabrication process of pixel detectors made of bulk cadmium telluride (CdTe) crystals. Prior to processing, the quality and defect density in CdTe material was characterized by infrared (IR) spectroscopy. The semiconductor detector and Flip-Chip (FC) interconnection processing was carried out in the clean room premises of Micronova Nanofabrication Centre in Espoo, Finland. The chip scale processes consist of the aluminum oxide (Al2O3) low temperature thermal Atomic Layer Deposition (ALD), titanium tungsten (TiW) metal sputtering depositions and an electroless Nickel growth. CdTe crystals with the size of 10×10×0.5 mm3 were patterned with several photo-lithography techniques. In this study, gold (Au) was chosen as the material for the wettable Under Bump Metalization (UBM) pads. Indium (In) based solder bumps were grown on PSI46dig read out chips (ROC) having 4160 pixels within an area of 1 cm2. CdTe sensor and ROC were hybridized using a low temperature flip-chip (FC) interconnection technique. The In-Au cold weld bonding connections were successfully connecting both elements. After the processing the detector packages were wire bonded into associated read out electronics. The pixel detectors were tested at the premises of Finnish Radiation Safety Authority (STUK). During the measurement campaign, the modules were tested by exposure to a 137Cs source of 1.5 TBq for 8 minutes. We detected at the room temperature a photopeak at 662 keV with about 2 % energy resolution.

  4. Evaluation of XRI-UNO CdTe detector for nuclear medical imaging

    International Nuclear Information System (INIS)

    Jambi, L.K.; Lees, J.E.; Bugby, S.L.; Alqahtani, M.S.; Tipper, S.; Perkins, A.C.

    2015-01-01

    Over the last two decades advances in semiconductor detector technology have reached the point where they are sufficiently sensitive to become an alternative to scintillators for high energy gamma ray detection for application in fields such as medical imaging. This paper assessed the Cadmium-Telluride (CdTe) XRI-UNO semiconductor detector produced by X-RAY Imatek for photon energies of interest in nuclear imaging. The XRI-UNO detector was found to have an intrinsic spatial resolution of <0.5mm and a high incident count rate capability up to at least 1680cps. The system spatial resolution, uniformity and sensitivity characteristics are also reported

  5. The semi-conductor detectors: art state, new concepts

    International Nuclear Information System (INIS)

    Pochet, T.

    1993-01-01

    After a brief recall of signal formation principle in a detector and of its different operation modes, the high Z materials as CdTe, HgI 2 , GaAs ,Ge and Si are presented, followed by the new 'thin layer' semiconductors

  6. Study on response function of CdTe detector

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunduk; Cho, Gyuseong [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Kang, Bo-Sun [Department of Radiological Science, Catholic University of Daegu, Kyoungsan, Kyoungbuk 712-702 (Korea, Republic of)], E-mail: bskang@cu.ac.kr

    2009-10-21

    So far the origin of the mechanism of light emission in the sonoluminescence has not elucidated whether it is due to blackbody radiation or bremsstrahlung. The final goal of our study is measuring X-ray energy spectrum using high-sensitivity cadmium telluride (CdTe) detector in order to obtain information for understanding sonoluminescence phenomena. However, the scope of this report is the measurement of X-ray spectrum using a high-resolution CdTe detector and determination of CdTe detector response function to obtain the corrected spectrum from measured soft X-ray source spectrum. In general, the measured spectrum was distorted by the characteristics of CdTe detector. Monte Carlo simulation code, MCNP, was used to obtain the reference response function of the CdTe detector. The X-ray spectra of {sup 57}Co, {sup 133}Ba, and {sup 241}Am were obtained by a 4x4x1.0(t) mm{sup 3} CdTe detector at room temperature.

  7. Evaluation of K x-ray escape and crosstalk in CdTe detectors and multi-channel detectors

    International Nuclear Information System (INIS)

    Ohtsuchi, Tetsuro; Ohmori, Koichi; Tsutsui, Hiroshi; Baba, Sueki

    1995-01-01

    The simple structure of CdTe semiconductor detectors facilitates their downsizing, and their possible application to radiographic sensors has been studied. The escape of K X-rays from these detectors increases with reduction of their dimensions and affects the measurements of X- and gamma-ray spectra. K X-rays also produce crosstalk in multi-channel detectors with adjacent channels. Therefore, K X-rays which escape from the detector elements degrade both the precision of energy spectra and spatial resolution. The ratios of escape peak integrated counts to total photon counts for various sizes of CdTe single detectors were calculated for gamma rays using the Monte Carlo method. Also, escape and crosstalk ratios were simulated for the CdTe multi-channel detectors. The theoretical results were tested experimentally for 59.54-keV gamma rays from a 241 Am radioactive source. Results showed that escape ratios for single detectors were strongly dependent on element size and thickness. The escape and crosstalk ratios increased with closer channel pitch. The calculated results showed a good agreement with the experimental data. The calculations made it clear that K X-rays which escaped to neighboring channels induced crosstalk more frequently at smaller channel pitch in multichannel detectors. A radiation shielding grid which blocked incident photons between the boundary channels was also tested by experiment and by calculation. It was effective in reducing the probability of escape and crosstalk

  8. Comparative study for small computer supported clearance determination with 131iodine hippuran using CdTe detectors

    International Nuclear Information System (INIS)

    Duerr, G.

    1986-01-01

    With the goal to work out a simple, non-invasive method for the total clearance determination also for immobile patients, we carried out this clearance study with CdTe semi-conductor detectors. The 131 iodine hippuran clearance determination was carried out on 69 patients in the nuclear medicine department of the Radiological Policlinic in the framework of a routine diagnosis with ambulant and stationary patients with a gamma camera and a connecting evaluation system. At the same time we recorded the shoulder curves using two CdTe semi-conductor detectors and deposited the data in a portable semi-conductor memory. Next the hypotheses for the routine use with the inclusion of commercially common small computers was worked out. The plasma disappearance curves which were recorded over the shoulder region were evaluated with a small computer according to the method of the modified Oberhausen tables and the Oberhausen formula. (orig./DG) [de

  9. Preliminary report on the development of a high resolution PET camera using semiconductor detectors

    International Nuclear Information System (INIS)

    Kikuchi, Yohei; Ishii, Keizo; Yamazaki, Hiromichi; Matsuyama, Shigeo; Yamaguchi, Takashi; Yamamoto, Yusuke; Sato, Takemi; Aoki, Yasushi; Aoki, Kenichi

    2005-01-01

    We are developing a PET camera using small semiconductor detectors, whose resolution is equivalent to the physical limit of spatial resolution. First, a coincidence system of 16 Schottky CdTe detectors of 0.5 mm width obtained a resolution of <1 mm and it was confirmed that the Schottky CdTe detector is suitable for high resolution PET. Next, the performance of a pair of 32 channel CdTe arrays (1.2 mm width per channel) was investigated for the development of the prototype of high resolution PET. The time resolution between opposing detector pair was 13 ns (FWHM) when high voltage (700 V) was applied. The image of a 0.6 mm diameter point source was obtained in an experiment with opposing detector arrays using four channels, indicating that, a higher resolution can be achieved with the 32 channel CdTe array

  10. Application of energy dispersive X-ray spectrometers with semiconductor detectors in radiometric analyses

    International Nuclear Information System (INIS)

    Jugelt, P.; Schieckel, M.

    1983-01-01

    Problems and possibilities of applying semiconductor detector spectrometers in radiometric analyses are described. A summary of the state of the art and tendencies of device engineering and spectra evaluation is given. Liquid-nitrogen cooled Li-drifted Si-detectors and high-purity Ge-detectors are compared. Semiconductor detectors working at room temperature are under development. In this connection CdTe and HgI 2 semiconductor detectors are compared. The use of small efficient computers in the spectrometer systems stimulates the development of algorithms for spectra analyses and for determining the concentration. Fields of application of energy dispersive X-ray spectrometers are X-ray diffraction and X-ray macroanalysis in investigating the structure of extensive surface regions

  11. 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 ...

  12. Characterization inconsistencies in CdTe and CZT gamma-ray detectors

    International Nuclear Information System (INIS)

    Lavietes, A.D.; McQuaid, J.H.

    1994-10-01

    In the past few years, significant developments in cadmium telluride (CdTe) and cadmium zinc telluride (CZT) semiconductor materials have taken place with respect to both quality and yield. Many of the more recent developments have occurred in the area of CZT crystal growth. This has resulted in an explosion of interest in the use of these materials in ambient temperature gamma-ray detectors. Most, if not all, of the manufacturers of CdTe and CZT have acquired government funding to continue research in development and applications, indicating the importance of these improvements in material quality. We have examined many detectors, along with the accompanying manufacturer's data, and it has become apparent that a clear standard does not exist by which each manufacturer characterizes the performance of their material. Result is a wide variety of performance claims that have no basis for comparison and normally cannot be readily reproduced. This paper first supports our observations and then proposes a standard that all manufacturers and users of these materials may use for characterization

  13. Study of the effect of the stress on CdTe nuclear detectors

    International Nuclear Information System (INIS)

    Ayoub, M.; Radley, I.; Mullins, J. T.; Hage-Ali, M.

    2013-01-01

    CdTe detectors are commonly used for X and γ ray applications. The performance of these detectors is strongly affected by different types of mechanical stress; such as that caused by differential expansion between the semiconductor and its intimate metallic contacts and that caused by applied pressure during the bonding process. The aim of this work was to study the effects of stress on the performance of CdTe detectors. A difference in expansion coefficients induces transverse stress under the metallic contact, while contact pressure induces longitudinal stress. These stresses have been simulated by applying known static pressures. For the longitudinal case, the pressure was applied directly to the metallic contact; while in the transverse case, it was applied to the side. We have studied the effect of longitudinal and transverse stresses on the electrical characteristics including leakage current measurements and γ-ray detection performance. We have also investigated induced defects, their nature, activation energies, cross sections, and concentrations under the applied stress by using photo-induced current transient spectroscopy and thermoelectric effect spectroscopy techniques. The operational stress limit is also given

  14. Study of the effect of the stress on CdTe nuclear detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ayoub, M.; Radley, I.; Mullins, J. T. [Kromek, Thomas Wright way, TS21 3FD, Sedgefield, County Durham (United Kingdom); Hage-Ali, M. [CLEA, Airport road, Beirut (Lebanon)

    2013-09-14

    CdTe detectors are commonly used for X and γ ray applications. The performance of these detectors is strongly affected by different types of mechanical stress; such as that caused by differential expansion between the semiconductor and its intimate metallic contacts and that caused by applied pressure during the bonding process. The aim of this work was to study the effects of stress on the performance of CdTe detectors. A difference in expansion coefficients induces transverse stress under the metallic contact, while contact pressure induces longitudinal stress. These stresses have been simulated by applying known static pressures. For the longitudinal case, the pressure was applied directly to the metallic contact; while in the transverse case, it was applied to the side. We have studied the effect of longitudinal and transverse stresses on the electrical characteristics including leakage current measurements and γ-ray detection performance. We have also investigated induced defects, their nature, activation energies, cross sections, and concentrations under the applied stress by using photo-induced current transient spectroscopy and thermoelectric effect spectroscopy techniques. The operational stress limit is also given.

  15. 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.

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

    International Nuclear Information System (INIS)

    Guerra, P; Santos, A; Darambara, D G

    2009-01-01

    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 3 CdZnTe pixellated detector.

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

    International Nuclear Information System (INIS)

    Oliveira, Icimone B.

    2011-01-01

    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)

  18. 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)

  19. 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)

  20. Thrombus detection using 125I-fibrinogen and a CdTe probe

    International Nuclear Information System (INIS)

    Garcia, D.A.; Frisbie, J.H.; Tow, D.E.; Sasahara, A.A.; Entine, G.

    1976-01-01

    A compact CdTe detector system was developed for use in a clinical screening test for venous thrombosis of the legs. Patients given intravenously administered autologous 125 I-fibrinogen were probed externally at selected points on the thighs and calves for abnormal accumulations of radioactivity. Measurements made with the CdTe probe were compared to those obtained with a standard portable NaI detector system. The CdTe probe was the equal of the NaI detector in diagnostic capability. The compact design of the semiconductor system considerably eased the probing procedure, especially in bedridden patients with limited mobility of the extremities

  1. 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...

  2. Development of an integrated response generator for Si/CdTe semiconductor Compton cameras

    International Nuclear Information System (INIS)

    Odaka, Hirokazu; Sugimoto, Soichiro; Ishikawa, Shin-nosuke; Katsuta, Junichiro; Koseki, Yuu; Fukuyama, Taro; Saito, Shinya; Sato, Rie; Sato, Goro; Watanabe, Shin

    2010-01-01

    We have developed an integrated response generator based on Monte Carlo simulation for Compton cameras composed of silicon (Si) and cadmium telluride (CdTe) semiconductor detectors. In order to construct an accurate detector response function, the simulation is required to include a comprehensive treatment of the semiconductor detector devices and the data processing system in addition to simulating particle tracking. Although CdTe is an excellent semiconductor material for detection of soft gamma rays, its ineffective charge transport property distorts its spectral response. We investigated the response of CdTe pad detectors in the simulation and present our initial results here. We also performed the full simulation of prototypes of Si/CdTe semiconductor Compton cameras and report on the reproducibility of detection efficiencies and angular resolutions of the cameras, both of which are essential performance parameters of astrophysical instruments.

  3. A New Approach for Evaluating Charge Transport Properties of Semiconductor Detectors

    International Nuclear Information System (INIS)

    Kim, Kyung O; Kim, Jong Kyung; Kim, Soon Young; Ha, Jang Ho

    2009-01-01

    The semiconductor detectors (e.g., CdTe, CdZnTe, and HgI 2 ) have been widely used for radiation detection and medical imaging because of its various outstanding features such as excellent energy resolution, wide bandgap energy, room temperature operation, and so on. Unfortunately, the performance of these detectors is mainly limited by the charge transport properties of semiconductor, especially the mobility-lifetime products (i.e., (μτ) e and ((μτ) h ). Hence, the analysis on the mobility-lifetime products is very important for evaluating correct characteristics of semiconductor detectors. A commonly used method to analyze the mobilitylifetime products is based on their responses to α particle. However, the α particle method cannot evaluate the ((μτ)h product in many cases, because a semiconductor detector operating at positive bias voltages often yields the energy spectrum without the peaks. This method is also known to be very sensitive to the experimental conditions as well as surface conditions of the detector. In this study, a new approach with gamma-ray instead of α particle was carried out to solve the determination difficulty of the ((μτ) h product with common method. The special relation between the two mobility-lifetime products, which we call the 'Nural equation', was also developed to simply obtain each parameter based on Hecht equation

  4. Performance optimization of CdTe and CdZnTe detectors for γ-spectrometry

    International Nuclear Information System (INIS)

    Montemont, Guillaume

    2000-01-01

    This study deals with room-temperature gamma spectrometry with CdTe and CdZnTe semiconductor detectors. The aim was the improvement of energy resolution and detection efficiency. Some different phenomena have been investigated. Electronic noise knowledge has enabled us to optimize the design of filtering. Charge transport induces signal shape uncertainty and the processing circuit has been adapted in order to account for these variations. Study and simulation of electrical current induction process has permitted the development of a new Frisch-grid based detection structure. We have reached 3% energy resolutions at 122 keV without detection efficiency loss. Finally, the remaining limits of detector performances have been estimated by focusing on gamma interaction phenomena and material non-uniformity problems. (author) [fr

  5. Quantitative analysis of polarization phenomena in CdTe radiation detectors

    International Nuclear Information System (INIS)

    Toyama, Hiroyuki; Higa, Akira; Yamazato, Masaaki; Maehama, Takehiro; Toguchi, Minoru; Ohno, Ryoichi

    2006-01-01

    Polarization phenomena in a Schottky-type CdTe radiation detector were studied. We evaluated the distribution of electric field in a biased CdTe detector by measuring the progressive change of Schottky barrier lowering with time. The parameters of deep acceptors such as detrapping time, concentration, and the depth of the energy level were quantitatively evaluated. In the case of applying the conventional model of charge accumulation, the obtained result shows that the CdTe bulk is never undepleted. We modified the charge accumulation model by taking account of the occupation state of the deep acceptor level. When a modified model is applied, the time that the depletion width in the bulk begins to diminish closely fits the time that the photopeak position begins to shift in radiation measurements. In this paper, we present a distribution of electric field during biasing and a simple method for the evaluation of the parameters of deep acceptors in CdTe bulk. (author)

  6. 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'lchiro; Takahashi, Tadayuki; Saito, Shinya; Glesener, Lindsay; Bultrago-Casas, Juan Camilo; Krucker, Sam; hide

    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 to 15 keV using the new technique of HXR focusing optics. The focal plane detector requires less than 100 micrometers position resolution (to take advantage of the angular resolution of the optics) and approximately equals 1 keV energy resolution (full width at half maximum (FWHM)) for spectroscopy down to 4 keV, with moderate cooling (greater than -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 micrometers for the second launch, we fabricated double-sided CdTe strip detectors with a position resolution of 60 micrometers 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 1 keV (FWHM) and low-energy threshold of approximately equals 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.

  7. A 90 element CdTe array detector

    Energy Technology Data Exchange (ETDEWEB)

    Iwase, Y.; Onozuka, A.; Ohmori, M. (Nippon Mining Co. Ltd., Toda, Saitama (Japan). Electronic Material and Components Labs.); Funaki, M. (Nippon Mining Co. Ltd., Toda, Saitama (Japan). Materials Development Research Labs.)

    1992-11-15

    The fabrication of a CdTe array radiation detector and its radiation detection characteristics are described. In order to obtain high efficiency of charge collection and realize uniform detection sensitivity, current-voltage characteristics with the combination of large and small barrier height contacts and three kinds of CdTe crystals have been investigated. It was found that the Schottky barrier height of electroless Pt deposition was 0.97 eV, which effectively suppressed electron injection. By using the crystal grown by the travelling heater method with a Cl concentration of 2 ppm, carrier lifetimes for electrons and holes of 1.0 and 0.5 [mu]s, respectively, were achieved. A 90 element array detector exhibited an energy resolution as low as 4.5 keV and a count rate variation of less than 5% for 60 keV [gamma]-rays. (orig.).

  8. A 90 element CdTe array detector

    Science.gov (United States)

    Iwase, Y.; Funaki, M.; Onozuka, A.; Ohmori, M.

    1992-11-01

    The fabrication of a CdTe array radiation detector and its radiation detection characteristics are described. In order to obtain high efficiency of charge collection and realize uniform detection sensitivity, current-voltage characteristics with the combination of large and small barrier height contacts and three kinds of CdTe crystals have been investigated. It was found that the Schottky barrier height of electroless Pt deposition was 0.97 eV, which effectively suppressed electron injection. By using the crystal grown by the travelling heater method with a Cl concentration of 2 ppm, carrier lifetimes for electrons and holes of 1.0 and 0.5 μs, respectively, were achieved. A 90 element array detector exhibited an energy resolution as low as 4.5 keV and a count rate variation of less than 5% for 60 keV γ-rays.

  9. Compound Semiconductor Radiation Detector

    International Nuclear Information System (INIS)

    Kim, Y. K.; Park, S. H.; Lee, W. G.; Ha, J. H.

    2005-01-01

    In 1945, Van Heerden measured α, β and γ radiations with the cooled AgCl crystal. It was the first radiation measurement using the compound semiconductor detector. Since then the compound semiconductor has been extensively studied as radiation detector. Generally the radiation detector can be divided into the gas detector, the scintillator and the semiconductor detector. The semiconductor detector has good points comparing to other radiation detectors. Since the density of the semiconductor detector is higher than that of the gas detector, the semiconductor detector can be made with the compact size to measure the high energy radiation. In the scintillator, the radiation is measured with the two-step process. That is, the radiation is converted into the photons, which are changed into electrons by a photo-detector, inside the scintillator. However in the semiconductor radiation detector, the radiation is measured only with the one-step process. The electron-hole pairs are generated from the radiation interaction inside the semiconductor detector, and these electrons and charged ions are directly collected to get the signal. The energy resolution of the semiconductor detector is generally better than that of the scintillator. At present, the commonly used semiconductors as the radiation detector are Si and Ge. However, these semiconductor detectors have weak points. That is, one needs thick material to measure the high energy radiation because of the relatively low atomic number of the composite material. In Ge case, the dark current of the detector is large at room temperature because of the small band-gap energy. Recently the compound semiconductor detectors have been extensively studied to overcome these problems. In this paper, we will briefly summarize the recent research topics about the compound semiconductor detector. We will introduce the research activities of our group, too

  10. A new MBE CdTe photoconductor array detector for X-ray applications

    International Nuclear Information System (INIS)

    Yoo, S.S.; Sivananthan, S.; Faurie, J.P.; Rodricks, B.; Bai, J.; Montano, P.A.; Argonne National Lab., IL

    1994-10-01

    A CdTe photoconductor array x-ray detector was grown using Molecular Beam Epitaxially (MBE) on a Si (100) substrate. The temporal response of the photoconductor arrays is as fast as 21 psec risetime and 38 psec Full Width Half Maximum (FWHM). Spatial and energy responses were obtained using x-rays from a rotating anode and synchrotron radiation source. The spatial resolution of the photoconductor was good enough to provide 75 microm FWHM using a 50 microm synchrotron x-ray beam. A substantial number of x-ray photons are absorbed effectively within the MBE CdTe layer as observed from the linear response up to 15 keV. These results demonstrate that MBE grown CdTe is a suitable choice of the detector materials to meet the requirements for x-ray detectors in particular for the new high brightness synchrotron sources

  11. 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.

  12. 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.

  13. Tests of UFXC32k chip with CdTe pixel detector

    Science.gov (United States)

    Maj, P.; Taguchi, T.; Nakaye, Y.

    2018-02-01

    The paper presents the performance of the UFXC32K—a hybrid pixel detector readout chip working with CdTe detectors. The UFXC32K has a pixel pitch of 75 μm and can cope with both input signal polarities. This functionality allows operating with widely used silicon sensors collecting holes and CdTe sensors collecting electrons. This article describes the chip focusing on solving the issues connected to high-Z sensor material, namely high leakage currents, slow charge collection time and thick material resulting in increased charge-sharring effects. The measurements were conducted with higher X-ray energies including 17.4 keV from molybdenum. Conclusions drawn inside the paper show the UFXC32K's usability for CdTe sensors in high X-ray energy applications.

  14. Preparation of High Purity CdTe for Nuclear Detector: Electrical and Nuclear Characterization

    Science.gov (United States)

    Zaiour, A.; Ayoub, M.; Hamié, A.; Fawaz, A.; Hage-ali, M.

    High purity crystal with controllable electrical properties, however, control of the electrical properties of CdTe has not yet been fully achieved. Using the refined Cd and Te as starting materials, extremely high-purity CdTe single crystals were prepared by the traditional vertical THM. The nature of the defects involved in the transitions was studied by analyzing the position of the energy levels by TSC method. The resolution of 4.2 keV (FWHM) confirms the high quality and stability of the detectors: TSC spectrum was in coherence with detectors spectrum with a horizontal plate between 0.2 and 0.6 eV. The enhancement in resolution of detectors with a full width at half- maximum (less than 0.31 meV), lead to confirm that the combination of vacuum distillation and zone refining was very effective to obtain more purified CdTe single crystals for photovoltaic or nuclear detectors with better physical properties.

  15. 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.)

  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. 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.

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

    International Nuclear Information System (INIS)

    Liu Yan; Shen Qihui; Shi Weiguang; Li Jixue; Liu Xiaoyang; Yu Dongdong; Zhou Jianguang

    2008-01-01

    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

  19. CdTe quantum dots for an application in the life sciences

    International Nuclear Information System (INIS)

    Thuy, Ung Thi Dieu; Toan, Pham Song; Chi, Tran Thi Kim; Liem, Nguyen Quang; Khang, Dinh Duy

    2010-01-01

    This report highlights the results of the preparation of semiconductor CdTe quantum dots (QDs) in the aqueous phase. The small size of a few nm and a very high luminescence quantum yield exceeding 60% of these materials make them promisingly applicable to bio-medicine labeling. Their strong, two-photon excitation luminescence is also a good characteristic for biolabeling without interference with the cell fluorescence. The primary results for the pH-sensitive CdTe QDs are presented in that fluorescence of CdTe QDs was used as a proton sensor to detect proton flux driven by adenosine triphosphate (ATP) synthesis in chromatophores. In other words, these QDs could work as pH-sensitive detectors. Therefore, the system of CdTe QDs on chromatophores prepared from the cells of Rhodospirillum rubrum and the antibodies against the beta-subunit of F0F1–ATPase could be a sensitive detector for the avian influenza virus subtype A/H5N1

  20. Time resolution improvement of Schottky CdTe PET detectors using digital signal processing

    International Nuclear Information System (INIS)

    Nakhostin, M.; Ishii, K.; Kikuchi, Y.; Matsuyama, S.; Yamazaki, H.; Torshabi, A. Esmaili

    2009-01-01

    We present the results of our study on the timing performance of Schottky CdTe PET detectors using the technique of digital signal processing. The coincidence signals between a CdTe detector (15x15x1 mm 3 ) and a fast liquid scintillator detector were digitized by a fast digital oscilloscope and analyzed. In the analysis, digital versions of the elements of timing circuits, including pulse shaper and time discriminator, were created and a digital implementation of the Amplitude and Rise-time Compensation (ARC) mode of timing was performed. Owing to a very fine adjustment of the parameters of timing measurement, a good time resolution of less than 9.9 ns (FWHM) at an energy threshold of 150 keV was achieved. In the next step, a new method of time pickoff for improvement of timing resolution without loss in the detection efficiency of CdTe detectors was examined. In the method, signals from a CdTe detector are grouped by their rise-times and different procedures of time pickoff are applied to the signals of each group. Then, the time pickoffs are synchronized by compensating the fixed time offset, caused by the different time pickoff procedures. This method leads to an improved time resolution of ∼7.2 ns (FWHM) at an energy threshold of as low as 150 keV. The methods presented in this work are computationally fast enough to be used for online processing of data in an actual PET system.

  1. Semiconductor interfaces of polycrystalline CdTe thin-film solar cells. Characterization and modification of electronic properties

    International Nuclear Information System (INIS)

    Fritsche, J.

    2003-01-01

    In this thesis for the first time the electronic properties of the semiconductor interfaces in polycrystalline CdTe thin-film solar cells, as well as the morphological and electronic properties of the single semiconductor surfaces were systematically characterized by surface-sensitive measuring methods. The morphological surface properties were analyzed by scanning force microscopy. As substrate materials with SnO 2 /ITO covered glass was applied, where the CdS and CdTe layers were deposited. Furthermore the electronic and morphological material properties of differently treated SnO 2 surfaces were characterized. Beside the studies with scanning force microscopy sputtering depth profiles and X-ray photoelectron spectroscopy were measured

  2. 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.

  3. Application of CdTe for the NeXT mission

    International Nuclear Information System (INIS)

    Takahashi, Tadayuki; Nakazawa, Kazuhiro; Watanabe, Shin; Sato, Goro; Mitani, Takefumi; Tanaka, Takaaki; Oonuki, Kousuke; Tamura, Ken'ichi; Tajima, Hiroyasu; Kamae, Tuneyoshi; Madejski, Greg; Nomachi, Masaharu; Fukazawa, Yasushi; Makishima, Kazuo; Kokubun, Motohide; Terada, Yukikatsu; Kataoka, Jun; Tashiro, Makoto

    2005-01-01

    Cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) have been regarded as promising semiconductor materials for hard X-ray and γ-ray detection. The high-atomic number of the materials (Z Cd =48,Z Te =52) gives a high quantum efficiency in comparison with Si. The large band-gap energy (E g =1.5eV) allows to operate the detector at room temperature. Based on recent achievements in high-resolution CdTe detectors, in the technology of ASICs and in bump-bonding, we have proposed the novel hard X-ray and γ-ray detectors for the NeXT mission in Japan. The high-energy response of the super mirror onboard NeXT will enable us to perform the first sensitive imaging observations up to 80keV. The focal plane detector, which combines a fully depleted X-ray CCD and a pixellated CdTe detector, will provide spectra and images in the wide energy range from 0.5 to 80keV. In the soft γ-ray band up to ∼ 1MeV, a narrow field-of-view Compton γ-ray telescope utilizing several tens of layers of thin Si or CdTe detector will provide precise spectra with much higher sensitivity than present instruments. The continuum sensitivity will reach several x10 -8 photons -1 keV -1 cm -2 in the hard X-ray region and a few x10 -7 photons -1 keV -1 cm -2 in the soft γ-ray region

  4. 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...

  5. Polycrystalline CdTe detectors: A luminosity monitor for the LHC

    Science.gov (United States)

    Gschwendtner, E.; Placidia, M.; Schmicklera, H.

    2003-09-01

    The luminosity at the four interaction points of the Large Hadron Collider must be continuously monitored in order to provide an adequate tool for the control and optimization of the collision parameters and the beam optics. At both sides of the interaction points absorbers are installed to protect the super-conducting accelerator elements from quenches caused by the deposited energy of collision products. The luminosity detectors will be installed in the copper core of these absorbers to measure the electromagnetic and hadronic showers caused by neutral particles that are produced at the proton-proton collision in the interaction points. The detectors have to withstand extreme radiation levels (108 Gy/yr at the design luminosity) and their long-term operation has to be assured without requiring human intervention. In addition the demand for bunch-by-bunch luminosity measurements, i.e. 40 MHz detection speed, puts severe constraints on the detectors. Polycrystalline CdTe detectors have a high potential to fulfill the requirements and are considered as LHC luminosity monitors. In this paper the interaction region is shown and the characteristics of the CdTe detectors are presented.

  6. Polycrystalline CdTe detectors: A luminosity monitor for the LHC

    International Nuclear Information System (INIS)

    Gschwendtner, E.; Placidia, M.; Schmicklera, H.

    2003-01-01

    The luminosity at the four interaction points of the Large Hadron Collider must be continuously monitored in order to provide an adequate tool for the control and optimization of the collision parameters and the beam optics. At both sides of the interaction points absorbers are installed to protect the super-conducting accelerator elements from quenches caused by the deposited energy of collision products. The luminosity detectors will be installed in the copper core of these absorbers to measure the electromagnetic and hadronic showers caused by neutral particles that are produced at the proton-proton collision in the interaction points. The detectors have to withstand extreme radiation levels (108 Gy/yr at the design luminosity) and their long-term operation has to be assured without requiring human intervention. In addition the demand for bunch-by-bunch luminosity measurements, i.e. 40 MHz detection speed, puts severe constraints on the detectors. Polycrystalline CdTe detectors have a high potential to fulfill the requirements and are considered as LHC luminosity monitors. In this paper the interaction region is shown and the characteristics of the CdTe detectors are presented

  7. Improvement of radiation response characteristic on CdTe detectors using fast neutron irradiation

    International Nuclear Information System (INIS)

    Miyamaru, Hiroyuki; Takahashi, Akito; Iida, Toshiyuki

    1999-01-01

    The treatment of fast neutron pre-irradiation was applied to a CdTe radiation detector in order to improve radiation response characteristic. Electron transport property of the detector was changed by the irradiation effect to suppress pulse amplitude fluctuation in risetime. Spectroscopic performance of the pre-irradiated detector was compared with the original. Additionally, the pre-irradiated detector was employed with a detection system using electrical signal processing of risetime discrimination (RTD). Pulse height spectra of 241 Am, 133 Ba, and 137 Cs gamma rays were measured to examine the change of the detector performance. The experimental results indicated that response characteristic for high-energy photons was improved by the pre-irradiation. The combination of the pre-irradiated detector and the RTD processing was found to provide further enhancement of the energy resolution. Application of fast neutron irradiation effect to the CdTe detector was demonstrated. (author)

  8. The use of portable semiconductor detectors in nuclear medicine

    International Nuclear Information System (INIS)

    Kuhn, W.

    1986-01-01

    A new biotelemetric system, CdTe semiconductor detectors with portable hard memory, for the registration of time activity curves in particular body regions of patients is introduced. The hard- and software connection of the system to the already present EDV configuration is described. The characteristics of the detectors are studied, theoretically explained and compared to the information given by the producers. By means of the determination of the ortho-iodine hippuric acid clearance (OIH) from the registration of the time activity curves in the chest the first information about the practicability in clinical use as well as the validity of the method are deduced. The detector system proved itself to be susceptible to problems, especially from manipulation of the cable or from movement of the patient. The determination of the OIH clearance from the partial body curve was problematic, because an extrapolation to the whole body based on the specific OIH kinetic in the small, observed tissue section is difficult. The comparison with the camera picture should be carefully evaluated, because this method has in principle the same inadequacies. (orig./HP) [de

  9. ASTRO-H CdTe detectors proton irradiation at PIF

    International Nuclear Information System (INIS)

    Limousin, O.; Renaud, D.; Horeau, B.; Dubos, S.; Laurent, P.; Lebrun, F.; Chipaux, R.; Boatella Polo, C.; Marcinkowski, R.; Kawaharada, M.; Watanabe, S.; Ohta, M.; Sato, G.; Takahashi, T.

    2015-01-01

    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

  10. Local polarization phenomena in In-doped CdTe x-ray detector arrays

    International Nuclear Information System (INIS)

    Sato, Toshiyuki; Sato, Kenji; Ishida, Shinichiro; Kiri, Motosada; Hirooka, Megumi; Yamada, Masayoshi; Kanamori, Hitoshi

    1995-01-01

    Local polarization phenomena have been studied in detector arrays with the detector element size of 500 microm x 500 microm, which are fabricated from high-resistivity In-doped CdTe crystals grown by the vertical Bridgman technique. It has been found for the first time that a polarization effect, which is characterized by a progressive decrease of the pulse counting rate with increasing photon fluence, strongly depends on the detector elements, that is, the portion of crystals used. The influence of several parameters, such as the applied electric field strength, time, and temperature, on this local polarization effect is also investigated. From the photoluminescence measurements of the inhomogeneity of In dopant, it is concluded that the local polarization effect observed here originates from a deep level associated with In dopant in CdTe crystals

  11. Semiconductor detectors in nuclear and particle physics

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1992-01-01

    Semiconductor detectors for elementary particle physics and nuclear physics in the energy range above 1 GeV are briefly reviewed. In these two fields semiconductor detectors are used mainly for the precise position sensing. In a typical experiment, the position of a fast charged particle crossing a relatively thin semiconductor detector is measured. The position resolution achievable by semiconductor detectors is compared with the resolution achievable by gas filled position sensing detectors. Semiconductor detectors are divided into two groups: Classical semiconductor diode detectors and semiconductor memory detectors. Principles of the signal formation and the signal read-out for both groups of detectors are described. New developments of silicon detectors of both groups are reported

  12. Semiconductor detectors in nuclear and particle physics

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1995-01-01

    Semiconductor detectors for elementary particle physics and nuclear physics in the energy range above 1 GeV are briefly reviewed. In these two fields semiconductor detectors are used mainly for the precise position sensing. In a typical experiment, the position of a fast charged particle crossing a relatively thin semiconductor detector is measured. The position resolution achievable by semiconductor detectors is compared with the resolution achievable by gas filled position sensing detectors. Semiconductor detectors are divided into two groups; (i) classical semiconductor diode detectors and (ii) semiconductor memory detectors. Principles of the signal formation and the signal read-out for both groups of detectors are described. New developments of silicon detectors of both groups are reported. copyright 1995 American Institute of Physics

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

    International Nuclear Information System (INIS)

    Billoud, T.; Leroy, C.; Papadatos, C.; Roux, J.S.; Pichotka, M.; Pospisil, 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 241 Am source, photons from a 137 Cs 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 (μ e τ e ) 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.

  14. Current state-of-the-art industrial and research applications using room-temperature CdTe and CdZnTe solid state detectors

    International Nuclear Information System (INIS)

    Eisen, Y.

    1996-01-01

    Improvements of CdTe crystal quality and significant progress in the growth of large ingots of high resistivity CdZnTe material enable the fabrication of larger area detectors in single element form or monolithic arrays. These advances allow for the development of imaging devices of improved spatial resolution for industrial, research and medical applications. CdTe and CdZnTe detectors operate in single photon counting mode or in current mode (charge integrating mode). The paper presents advantages of CdTe and CdZnTe over common scintillator type detectors, but also presents the shortcomings of the former detectors with respect to charge collection which limit the yields of good spectrometers. The paper reviews industrial and research applications utilizing these detectors and in particular describes in detail two imaging systems for security screening and custom inspection. These systems are characterized by large dynamic range and good spatial resolution and are composed of large arrays of CdTe spectrometers and discriminator grade detectors. A wide energy range detector assembly, for astrophysical research of gamma ray bursts composed of CdTe, HgI 2 and CdZnTe spectrometers in two dimensional arrays is also presented. (orig.)

  15. State of the art in semiconductor detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1990-01-01

    The state of the art in semiconductor detectors for elementary particle physics and X-ray astronomy is briefly reviewed. Semiconductor detectors are divided into two groups; i) classical semiconductor diode detectors and ii) semiconductor memory detectors. Principles of signal formation for both groups of detectors are described and their performance is compared. New developments of silicon detectors are reported here. (orig.)

  16. State of the art in semiconductor detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1989-01-01

    The state of the art in semiconductor detectors for elementary particle physics and x-ray astronomy is briefly reviewed. Semiconductor detectors are divided into two groups; classical semiconductor diode detectors; and semiconductor memory detectors. Principles of signal formation for both groups of detectors are described and their performance is compared. New developments of silicon detectors are reported here. 13 refs., 8 figs

  17. Pulse-height loss in the signal readout circuit of compound semiconductor detectors

    Science.gov (United States)

    Nakhostin, M.; Hitomi, K.

    2018-06-01

    Compound semiconductor detectors such as CdTe, CdZnTe, HgI2 and TlBr are known to exhibit large variations in their charge collection times. This paper considers the effect of such variations on the measurement of induced charge pulses by using resistive feedback charge-sensitive preamplifiers. It is shown that, due to the finite decay-time constant of the preamplifiers, the capacitive decay during the signal readout leads to a variable deficit in the measurement of ballistic signals and a digital pulse processing method is employed to correct for it. The method is experimentally examined by using sampled pulses from a TlBr detector coupled to a charge-sensitive preamplifier with 150 μs of decay-time constant and 20 % improvement in the energy resolution of the detector at 662 keV is achieved. The implications of the capacitive decay on the correction of charge-trapping effect by using depth-sensing technique are also considered.

  18. Progress in semiconductor drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Walton, J.; Gatti, E.

    1985-01-01

    Progress in testing semiconductor drift detectors is reported. Generally better position and energy resolutions were obtained than resolutions published previously. The improvement is mostly due to new electronics better matched to different detectors. It is shown that semiconductor drift detectors are becoming versatile and reliable detectors for position and energy measurements

  19. 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.

  20. Physical principles of semiconductor detectors

    International Nuclear Information System (INIS)

    Micek, S.L.

    1979-01-01

    The general properties of semiconductors with respect to the possibilities of their use as the ionization radiation detectors are discussed. Some chosen types of semiconductor junctions and their characteristics are briefly presented. There are also discussed the physical phenomena connected with the formation of barriers in various types of semiconductor counters. Finally, the basic properties of three main types of semiconductor detectors are given. (author)

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

    International Nuclear Information System (INIS)

    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.

    2000-01-01

    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 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 infarct

  2. Metal-semiconductor, composite radiation detectors

    International Nuclear Information System (INIS)

    Orvis, W.J.; Yee, J.H.; Fuess, D.A.

    1991-12-01

    In 1989, Naruse and Hatayama of Toshiba published a design for an increased efficiency x-ray detector. The design increased the efficiency of a semiconductor detector by interspersing layers of high-z metal within it. Semiconductors such as silicon make good, high-resolution radiation detectors, but they have low efficiency because they are low-z materials (z = 14). High-z metals, on the other hand, are good absorbers of high-energy photons. By interspersing high-z metal layers with semiconductor layers, Naruse and Hatayama combined the high absorption efficiency of the high-z metals with good detection capabilities of a semiconductor. This project is an attempt to use the same design to produce a high- efficiency gamma ray detector. By their nature, gamma rays require thicker metal layers to efficiently absorb them. These thicker layers change the behavior of the detector by reducing the resolution, compared to a solid state detector, and shifting the photopeak by a predictable amount. During the last year, we have modeled parts of the detector and have nearly completed a prototype device. 2 refs

  3. 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...

  4. Energy dispersive CdTe and CdZnTe detectors for spectral clinical CT and NDT applications

    Energy Technology Data Exchange (ETDEWEB)

    Barber, W.C., E-mail: william.barber@dxray.com [DxRay, Inc., Northridge, CA (United States); Interon AS, Asker (Norway); Wessel, J.C. [DxRay, Inc., Northridge, CA (United States); Interon AS, Asker (Norway); Nygard, E. [Interon AS, Asker (Norway); Iwanczyk, J.S. [DxRay, Inc., Northridge, CA (United States)

    2015-06-01

    We are developing room temperature compound semiconductor detectors for applications in energy-resolved high-flux single x-ray photon-counting spectral computed tomography (CT), including functional imaging with nanoparticle contrast agents for medical applications and non-destructive testing (NDT) for security applications. Energy-resolved photon-counting can provide reduced patient dose through optimal energy weighting for a particular imaging task in CT, functional contrast enhancement through spectroscopic imaging of metal nanoparticles in CT, and compositional analysis through multiple basis function material decomposition in CT and NDT. These applications produce high input count rates from an x-ray generator delivered to the detector. Therefore, in order to achieve energy-resolved single photon counting in these applications, a high output count rate (OCR) for an energy-dispersive detector must be achieved at the required spatial resolution and across the required dynamic range for the application. The required performance in terms of the OCR, spatial resolution, and dynamic range must be obtained with sufficient field of view (FOV) for the application thus requiring the tiling of pixel arrays and scanning techniques. Room temperature cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) compound semiconductors, operating as direct conversion x-ray sensors, can provide the required speed when connected to application specific integrated circuits (ASICs) operating at fast peaking times with multiple fixed thresholds per pixel provided the sensors are designed for rapid signal formation across the x-ray energy ranges of the application at the required energy and spatial resolutions, and at a sufficiently high detective quantum efficiency (DQE). We have developed high-flux energy-resolved photon-counting x-ray imaging array sensors using pixellated CdTe and CdZnTe semiconductors optimized for clinical CT and security NDT. We have also fabricated high

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

    International Nuclear Information System (INIS)

    Ede, Anthony

    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 γ-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 preliminary results from the fabricated films presented. Attention is then turned to the CdS/CdTe films that are produced commercially for the photovoltaic industry. In this case the crystalline nature, surface topography and optical properties are investigated. A conclusion examines the progress that has been made towards the development of a large area fiat panel digital imaging technique. (author)

  6. Feasibility study on BNCT-SPECT using a CdTe detector

    International Nuclear Information System (INIS)

    Murata, Isao; Mukai, Taiki; Ito, Masao; Miyamaru, Hiroyuki; Yoshida, Shigeo

    2011-01-01

    There is no doubt that boron neutron capture therapy (BNCT) is a promising cancer therapy in the near future. At present, one of the severest problems to solve is monitoring of the treatment effect during neutron irradiation. It is known to be difficult in real time. So far, activation foils, small detectors and so on were used to measure the thermal neutron fluence in a certain place of the tumor. The dose distribution is thus estimated from the measured result and prediction with a transport code. In the present study, 478 keV gamma-rays emitted from the excited state of 7 Li produced by 10 B(n,α) 7 Li reaction are directly measured to realize real time monitoring of the treatment effect of BNCT. In this paper, the result of the feasibility study carried out using a Monte Carlo transport code is summarized. We used CdTe detectors with a quite narrow collimator to obtain a BNCT image keeping good spatial resolution. The intensity of capture gamma-rays of 2223 keV produced by 1 H(n,γ) 2 H reaction is very much higher than that of 478 keV. We thus adjusted the detector efficiency by selecting an appropriate thickness so as to optimize the efficiency ratio between 478 and 2223 keV. From the result of the detector response calculation, in case of 20 mm thick CdTe detector with the collimator of 2 mm in diameter, sufficient net count of ∼1000 for 478 keV in 30 min. was realized. It means an efficient and high-resolution BNCT-SPECT image could be obtained. (author)

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

    International Nuclear Information System (INIS)

    Marin, E.; Calderon, A.; Vigil G, O.; Sastre, J.; Contreras P, G.; Aguilar H, J.; Saucedo, E.; Ruiz, C.M.

    2006-01-01

    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 μm, for which it is difficult to measure, by means of optical techniques, absorption coefficients greater than 10 3 cm -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 growth

  9. Spectroscopic Imaging Using Ge and CdTe Based Detector Systems for Hard X-ray Applications

    Science.gov (United States)

    Astromskas, Vytautas

    Third generation synchrotron facilities such as the Diamond Light Source (DLS) have a wide range of experiments performed for a wide range of science fields. The DLS operates at energies up to 150 keV which introduces great challenges to radiation detector technology. This work focuses on the requirements that the detector technology faces for X-ray Absorption Fine Structure (XAFS) and powder diffraction experiments in I12 and I15 beam lines, respectively. A segmented HPGe demonstrator detector with in-built charge sensitive CUBE preamplifiers and a Schottky e- collection CdTe Medipix3RX detector systems were investigated to understand the underlying mechanisms that limit spectroscopic, imaging performances and stability and to find ways to overcome or minimise those limitations. The energy resolution and stability of the Ge demonstrator detector was found to have the required characteristics for XAFS measurements. Charge sharing was identified as a limiting factor to the resolution which is going to be addressed in the future development of a full detector system as well as reductions in electronic noise and cross-talk effects. The stability study of the Schottky CdTe Medipix3RX detector showed that polarization is highly dependent on temperature, irradiation duration and incoming flux. A new pixel behaviour called tri-phase (3-P) pixel was identified and a novel method for determining optimum operational conditions was developed. The use of the 3-P pixels as a criterion for depolarization resulted in a stable performance of the detector. Furthermore, the detector was applied in powder diffraction measurement at the I15 beam line and resulted in the detector diffraction pattern matching the simulated data. CdTe Medipix3RX and HEXITEC spectroscopic imaging detectors were applied in identification and discrimination of transitional metals for security application and K-edge subtraction for medical applications. The results showed that both detectors have potential

  10. Semiconductor detectors with proximity signal readout

    International Nuclear Information System (INIS)

    Asztalos, Stephen J.

    2012-01-01

    Semiconductor-based radiation detectors are routinely used for the detection, imaging, and spectroscopy of x-rays, gamma rays, and charged particles for applications in the areas of nuclear and medical physics, astrophysics, environmental remediation, nuclear nonproliferation, and homeland security. Detectors used for imaging and particle tracking are more complex in that they typically must also measure the location of the radiation interaction in addition to the deposited energy. In such detectors, the position measurement is often achieved by dividing or segmenting the electrodes into many strips or pixels and then reading out the signals from all of the electrode segments. Fine electrode segmentation is problematic for many of the standard semiconductor detector technologies. Clearly there is a need for a semiconductor-based radiation detector technology that can achieve fine position resolution while maintaining the excellent energy resolution intrinsic to semiconductor detectors, can be fabricated through simple processes, does not require complex electrical interconnections to the detector, and can reduce the number of required channels of readout electronics. Proximity electrode signal readout (PESR), in which the electrodes are not in physical contact with the detector surface, satisfies this need

  11. 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.

  12. Semiconductor radiation detectors. Device physics

    International Nuclear Information System (INIS)

    Lutz, G.

    2007-01-01

    Starting from basic principles, the author, whose own contributions to these developments have been significant, describes the rapidly growing field of modern semiconductor detectors used for energy and position measurement radiation. This development was stimulated by requirements in elementary particle physics where it has led to important scientific discoveries. It has now spread to many other fields of science and technology. The book is written in a didactic way and includes an introduction to semiconductor physics. The working principles of semiconductor radiation detectors are explained in an intuitive way, followed by formal quantitative analysis. Broad coverage is also given to electronic signal readout and to the subject of radiation damage. The book is the first to comprehensively cover the semiconductor radiation detectors currently in use. It is useful as a teaching guide and as a reference work for research and applications. (orig.)

  13. 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.)

  14. Semiconductor high-energy radiation scintillation detector

    International Nuclear Information System (INIS)

    Kastalsky, A.; Luryi, S.; Spivak, B.

    2006-01-01

    We propose a new scintillation-type detector in which high-energy radiation generates 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. An important advantage of the proposed detector is its fast response time, about 1 ns, essentially limited only by the recombination time of minority carriers. Notably, the fast response comes without any degradation in brightness. When the scintillator is implemented in a qualified semiconductor material (such as InP or GaAs), the photo-detector and associated circuits can be epitaxially integrated on the scintillator slab and the structure can be stacked-up to achieve virtually any desired absorption capability

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

    Energy Technology Data Exchange (ETDEWEB)

    Marchelek, M. [Department of Environmental Technology, Faculty of Chemistry, University of Gdansk Wita Stwosza 63, 80-952 Gdansk (Poland); Grabowska, E., E-mail: ewelina.grabowska@ug.edu.pl [Department of Environmental Technology, Faculty of Chemistry, University of Gdansk Wita Stwosza 63, 80-952 Gdansk (Poland); Klimczuk, T. [Department of Solid State Physics, Faculty of Applied Physics and Mathematics, Gdansk University of Technology, G. Narutowicza 11/12, 80-233 Gdansk (Poland); Lisowski, W. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44-52, 01-224 Warsaw (Poland); Zaleska-Medynska, A. [Department of Environmental Technology, Faculty of Chemistry, University of Gdansk Wita Stwosza 63, 80-952 Gdansk (Poland)

    2017-01-30

    Highlights: • Novel semiconductors decorated by CdTe QDs and/or Pt NPs were synthesized. • Photodeposition and radiolysis is an effective method to obtaining Pt NPs. • CdTe decorated samples were prepared by absorption of QDs on matrix surface. • KTaO{sub 3}/CdTe-Pt{sub (R)} showed highest photocatalytic performance. • The enhanced performance was associated with electron trap mechanism. - Abstract: A novel synthesis process was used to prepare TiO{sub 2} microspheres, TiO{sub 2} P-25, SrTiO{sub 3} and KTaO{sub 3} 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 TiO{sub 2} microspheres, P25, SrTiO{sub 3} and KTaO{sub 3} 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 KTaO{sub 3}/CdTe-Pt{sub (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 KTaO{sub 3}.

  16. Hybrid anode for semiconductor radiation detectors

    Science.gov (United States)

    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).

  17. Semiconductors detectors: basics principals, fabrication and repair

    International Nuclear Information System (INIS)

    Souza Coelho, L.F. de.

    1982-05-01

    The fabrication and repairing techniques of semiconductor detectors, are described. These methods are shown in the way they are applied by the semiconductor detector laboratory of the KFA-Julich, where they have been developed during the last 15 years. The history of the semiconductor detectors is presented here, being also described the detector fabrication experiences inside Brazil. The key problems of manufacturing are raised. In order to understand the fabrication and repairing techniques the working principles of these detectors, are described. The cases in which worked during the stay in the KFA-Julich, particularly the fabrication of a plane Ge (Li) detector, with side entry, and the repair of a coaxial Ge (Li) is described. The vanguard problems being researched in Julich are also described. Finally it is discussed a timetable for the semiconductor detector laboratory of the UFRJ, which laboratory is in the mounting stage now. (Author) [pt

  18. 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

  19. Metal-semiconductor, composite radiation detectors

    International Nuclear Information System (INIS)

    Orvis, W.J.; Yee, J.H.; Fuess, D.

    1992-12-01

    In 1989, Naruse and Hatayama of Toshiba published a design for an increased efficiency x-ray detector. The design increased the efficiency of a semiconductor detector by interspersing layers of high-z metal within it. Semiconductors such as silicon make good, high-resolution radiation detectors, but they have low efficiency because they are low-z materials (z = 14). High-z metals, on the other hand, are good absorbers of high-energy photons. By interspersing high-z metal layers with semiconductor layers, Naruse and Hatayama combined the high absorption efficiency of the high-z metals with the good detection capabilities of a semiconductor. This project is an attempt to use the same design to produce a high-efficiency, room temperature gamma ray detector. By their nature, gamma rays require thicker metal layers to efficiently absorb them. These thicker layers change the behavior of the detector by reducing the resolution, compared to a solid state detector, and shifting the photopeak by a predictable amount. During the last year, the authors have procured and tested a commercial device with operating characteristics similar to those of a single layer of the composite device. They have modeled the radiation transport in a multi-layered device, to verify the initial calculations of layer thickness and composition. They have modeled the electrostatic field in different device designs to locate and remove high-field regions that can cause device breakdown. They have fabricated 14 single layer prototypes

  20. 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...

  1. CdTe and Cd1-xZnxTe for nuclear detectors: facts and fictions

    International Nuclear Information System (INIS)

    Fougeres, P.; Siffert, P.; Hageali, M.; Koebel, J.M.; Regal, R.

    1999-01-01

    Both CdTe and Cd 1-x Zn x Te (CZT) can be considered from their physical properties as very good materials for room temperature X- and γ-rays detection. However, despite years of intense material research, no significant advance has been made to help one to choose between both semiconductors. This paper reviews a few facts about CdTe and CZT to attempt to draw a real comparison between both. THM-CdTe and HPB-CZT have been grown and characterized in Strasbourg. Crystal growth, alloying effects, transport properties and defects are reviewed on the basis of our results and the published ones. The results show that it is still very difficult to claim which one is the best

  2. Review of CdTe medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Entine, G; Garcia, D A; Tow, D E

    1977-02-01

    CdTe sensors are now being used in several areas of nuclear medicine. CdTe probe technics, originally developed to study dental pathology in dog models, are being used clinically to diagnose venous thrombosis of the legs and to detect occult dental infections in patients scheduled for prosthetic cardiovascular and orthopedic surgery. Similar instrumentation is in use in animal research of myocardial infarction and synthetic tooth substitutes. Transmission technics have also been developed to diagnose pulmonary edema and to measure bone mineral changes in space flight. Investigations are also underway in the use of linear or two-dimensional arrays of CdTe gamma sensors for medical imaging. Economic considerations have slowed this work, but the technology appears to be available. Development of photoconductive CdTe X-ray detectors for scintigraphic scanners has also begun. Rapid detector improvement will be needed for success in this field, but the potential usefulness is very great. Together, the present application results are encouraging and wide use of CdTe detectors should occur within only a few years.

  3. Polycrystalline CdTe Detectors A Luminosity Monitor for the LHC

    CERN Document Server

    Gschwendtner, E; Schmickler, Hermann

    2003-01-01

    The luminosity at the four interaction points of the Large Hadron Collider must be continuously monitored in order to provide an adequate tool for the control and optimization of the collision parameters and the beam optics. At both sides of the interaction points absorbers are installed to protect the super-conducting accelerator elements from quenches causes by the deposited energy of collision products. The luminosity detectors will be installed in the copper core of these absorbers to measure the electromagnetic and hadronic showers caused by neutral particles that are produced at the proton-proton collision in the interaction points. The detectors have to withstand extreme radiation levels (10^8 Gy/yr at the design luminosity) and their long-term operation has to be assured without requiring humain intervention. In addition the demand for bunch-by-bunch luminosity measurements, i.e. 40MHz detection speed, puts severe constraints on the detectors. Polycrystalline CdTe detectors have a high potential to fu...

  4. Design and Performance of Soft Gamma-ray Detector for NeXT Mission

    Science.gov (United States)

    Tajima, H.; Kamae, T.; Madejski, G.; Takahashi, T.; Nakazawa, K.; Watanabe, S.; Mitani, T.; Tanaka, T.; Fukazawa, Y.; Kataoka, J.; Ikagawa, T.; Kokubun, M.; Makishima, K.; Terada, Y.; Nomachi, M.; Tashiro, M.

    The Soft Gamma-ray Detector (SGD) on board NeXT (Japanese future high energy astrophysics mission) is a Compton telescope with narrow field of view, which utilizes Compton kinematics to enhance its background rejection capabilities. It is realized as a hybrid semiconductor gamma-ray detector which consists of silicon and Cadmium Telluride (CdTe) detectors. It can detect photons in an energy band 0.05-1 MeV at a background level of 5×10-7 counts/s/cm2/keV; the silicon layers are required to improve the performance at a lower energy band (development of key technologies to realize the SGD; high quality CdTe, low noise front-end VLSI and bump bonding technology. Energy resolutions of 1.7 keV (FWHM) for CdTe pixel detectors and 1.1 keV for silicon strip detectors have been measured. We also present the validation of Monte Carlo simulation used to evaluate the performance of the SGD.

  5. Self-Catalyzed CdTe Wires

    Directory of Open Access Journals (Sweden)

    Tom Baines

    2018-04-01

    Full Text Available CdTe wires have been fabricated via a catalyst free method using the industrially scalable physical vapor deposition technique close space sublimation. Wire growth was shown to be highly dependent on surface roughness and deposition pressure, with only low roughness surfaces being capable of producing wires. Growth of wires is highly (111 oriented and is inferred to occur via a vapor-solid-solid growth mechanism, wherein a CdTe seed particle acts to template the growth. Such seed particles are visible as wire caps and have been characterized via energy dispersive X-ray analysis to establish they are single phase CdTe, hence validating the self-catalysation route. Cathodoluminescence analysis demonstrates that CdTe wires exhibited a much lower level of recombination when compared to a planar CdTe film, which is highly beneficial for semiconductor applications.

  6. CdTe and CdZnTe gamma ray detectors for medical and industrial imaging systems

    International Nuclear Information System (INIS)

    Eisen, Y.; Shor, A.; Mardor, I.

    1999-01-01

    CdTe and CdZnTe X-ray and gamma ray detectors in the form of single elements or as segmented monolithic detectors have been shown to be useful in medical and industrial imaging systems. These detectors possess inherently better energy resolution than scintillators coupled to either photodiodes or photomultipliers, and together with application specific integrated circuits they lead to compact imaging systems of enhanced spatial resolution and better contrast resolution. Photopeak efficiencies of these detectors is greatly affected by a relatively low hole mobility-lifetime product. Utilizing these detectors as highly efficient good spectrometers, demands use of techniques to improve their charge collection properties, i.e., correct for variations in charge losses at different depths of interaction in the detector. The corrections for the large hole trapping are made either by applying electronic techniques or by fabricating detector or electrical contacts configurations which differ from the commonly used planar detectors. The following review paper is divided into three parts: The first part discusses detector contact configurations for enhancing photopeak efficiencies and the single carrier collection approach which leads to improved energy resolutions and photopeak efficiencies at high gamma ray energies. The second part demonstrates excellent spectroscopic results using thick CdZnTe segmented monolithic pad and strip detectors showing energy resolutions less than 2% FWHM at 356 keV gamma rays. The third part discusses advantages and disadvantages of CdTe and CdZnTe detectors in imaging systems and describes new developments for medical diagnostics imaging systems

  7. 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.

  8. Semiconductor Detectors

    International Nuclear Information System (INIS)

    Cortina, E.

    2007-01-01

    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)

  9. Possible use of CdTe detectors in kVp monitoring of diagnostic X-ray tubes

    International Nuclear Information System (INIS)

    Krmar, M.; Bucalovic, N.; Baucal, M.; Jovancevic, 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 non-invasive 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.

  10. Spectral resolution and high-flux capability tradeoffs in CdTe detectors for clinical CT.

    Science.gov (United States)

    Hsieh, Scott S; Rajbhandary, Paurakh L; Pelc, Norbert J

    2018-04-01

    Photon-counting detectors using CdTe or CZT substrates are promising candidates for future CT systems but suffer from a number of nonidealities, including charge sharing and pulse pileup. By increasing the pixel size of the detector, the system can improve charge sharing characteristics at the expense of increasing pileup. The purpose of this work is to describe these considerations in the optimization of the detector pixel pitch. The transport of x rays through the CdTe substrate was simulated in a Monte Carlo fashion using GEANT4. Deposited energy was converted into charges distributed as a Gaussian function with size dependent on interaction depth to capture spreading from diffusion and Coulomb repulsion. The charges were then collected in a pixelated fashion. Pulse pileup was incorporated separately with Monte Carlo simulation. The Cramér-Rao lower bound (CRLB) of the measurement variance was numerically estimated for the basis material projections. Noise in these estimates was propagated into CT images. We simulated pixel pitches of 250, 350, and 450 microns and compared the results to a photon counting detector with pileup but otherwise ideal energy response and an ideal dual-energy system (80/140 kVp with tin filtration). The modeled CdTe thickness was 2 mm, the incident spectrum was 140 kVp and 500 mA, and the effective dead time was 67 ns. Charge summing circuitry was not modeled. We restricted our simulations to objects of uniform thickness and did not consider the potential advantage of smaller pixels at high spatial frequencies. At very high x-ray flux, pulse pileup dominates and small pixel sizes perform best. At low flux or for thick objects, charge sharing dominates and large pixel sizes perform best. At low flux and depending on the beam hardness, the CRLB of variance in basis material projections tasks can be 32%-55% higher with a 250 micron pixel pitch compared to a 450 micron pixel pitch. However, both are about four times worse in variance

  11. Miniature semiconductor detectors for in vivo dosimetry

    International Nuclear Information System (INIS)

    Rosenfeld, A. B.; Cutajar, D.; Lerch, M. L. F.; Takacs, G.; Cornelius, I. M.; Yudelev, M.; Zaider, M.

    2006-01-01

    Silicon mini-semiconductor detectors are found in wide applications for in vivo personal dosimetry and dosimetry and Micro-dosimetry of different radiation oncology modalities. These applications are based on integral and spectroscopy modes of metal oxide semiconductor field effect transistor and silicon p-n junction detectors. The advantages and limitations of each are discussed. (authors)

  12. 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)

  13. TCT characterization of different semiconductor materials for particle detection

    International Nuclear Information System (INIS)

    Fink, J.; Lodomez, P.; Krueger, H.; Pernegger, H.; Weilhammer, P.; Wermes, N.

    2006-01-01

    The development of digital semiconductor based X-ray detectors necessitates a detailed understanding of the applied sensor material. Under this premise a broad-band transient current technique (TCT) setup has been developed and used to characterize different semiconductors. The measurements are based on the generation of electrical charges within the sensor material and the subsequent time-resolved analysis of the charge carrier movement. From the recorded current pulses the charge collection efficiency, the charge carrier mobility and the electric field profile have been extracted. The examined materials are silicon p in n diodes, ohmic and Schottky contacted CdTe detectors, CdZnTe (CZT) crystals with Schottky contacts as well as two single-crystal CVD-diamonds

  14. Basic performance and stability of a CdTe solid-state detector panel.

    Science.gov (United States)

    Tsuchiya, Katsutoshi; Takahashi, Isao; Kawaguchi, Tsuneaki; Yokoi, Kazuma; Morimoto, Yuuichi; Ishitsu, Takafumi; Suzuki, Atsurou; Ueno, Yuuichirou; Kobashi, Keiji

    2010-05-01

    We have developed a prototype gamma camera system (R1-M) using a cadmium telluride (CdTe) detector panel and evaluated the basic performance and the spectral stability. The CdTe panel consists of 5-mm-thick crystals. The field of view is 134 x 268 mm comprising 18,432 pixels with a pixel pitch of 1.4 mm. Replaceable small CdTe modules are mounted on to the circuit board by dedicated zero insertion force connectors. To make the readout circuit compact, the matrix read out is processed by dedicated ASICs. The panel is equipped with a cold-air cooling system. The temperature and humidity in the panel were kept at 20 degrees C and below 70% relative humidity. CdTe polarization was suppressed by the bias refresh technique to stabilize the detector. We also produced three dedicated square pixel-matched collimators: LEGP (20 mm-thick), LEHR (27 mm-thick), and LEUHR (35 mm-thick). We evaluated their basic performance (energy resolution, system resolution, and sensitivity) and the spectral stability in terms of short-term (several hours of continuous acquisition) and long-term (infrequent measurements over more than a year) activity. The intrinsic energy resolution (FWHM) acquired with Tc-99m (140.5 keV) was 6.6%. The spatial resolutions (FWHM at a distance of 100 mm) with LEGP, LEHR, and LEUHR collimators were 5.7, 4.9, and 4.2 mm, and the sensitivities were 71, 39, and 23 cps/MBq, respectively. The energy peak position and the intrinsic energy resolution after several hours of operation were nearly the same as the values a few minutes after the system was powered on; the variation of the peak position was <0.2%, and that of the resolution was about 0.3%. Infrequent measurements conducted over a year showed that the variations of the energy peak position and the intrinsic energy resolution of the system were at a similar level to those described above. The basic performance of the CdTe-gamma camera system was evaluated, and its stability was verified. It was shown that the

  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. 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...

  17. Development of surgical gamma probes with TlBr semiconductors and CsI(Tl) scintillators crystals

    International Nuclear Information System (INIS)

    Costa, Fabio Eduardo da

    2006-01-01

    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)

  18. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  19. Semiconductor ionizino. radiation detectors

    International Nuclear Information System (INIS)

    1982-01-01

    Spectrometric semiconductor detectors of ionizing radiation with the electron-hole junction, based on silicon and germanium are presented. The following parameters are given for the individual types of germanium detectors: energy range of detected radiation, energy resolution given as full width at half maximum (FWHM) and full width at one tenth of maximum (FWTM) for 57 Co and 60 Co, detection sensitivity, optimal voltage, and electric capacitance at optimal voltage. For silicon detectors the value of FWHM for 239 Pu is given, the sensitive area and the depth of the sensitive area. (E.S.)

  20. Pixellated thallium bromide detectors for gamma-ray spectroscopy and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Onodera, T. E-mail: tosiyuki@smail.tohtech.ac.jp; Hitomi, K.; Shoji, T.; Hiratate, Y

    2004-06-01

    Recently, pixellated semiconductor detectors exhibit high-energy resolution, which have been studied actively and fabricated from CdTe, CZT and HgI{sub 2}. Thallium bromide (TlBr) is a compound semiconductor characterized with its high atomic numbers (Tl=81, Br=35) and high density (7.56 g/cm{sup 3}). Thus, TlBr exhibits higher photon stopping power than other semiconductor materials used for radiation detector fabrication such as CdTe, CZT and HgI{sub 2}. The wide band gap of TlBr (2.68 eV) permits the detectors low-noise operation at around room temperature. Our studies made an effort to fabricate pixellated TlBr detectors had sufficient detection efficiency and good charge collection efficiency. In this study, pixellated TlBr detectors were fabricated from the crystals purified by the multipass zone-refining method and grown by the horizontal traveling molten zone (TMZ) method. The TlBr detector has a continuous cathode over one crystal surface and 3x3 pixellated anodes (0.57x0.57 mm{sup 2} each) surrounded by a guard ring on the opposite surface. The electrodes were realized by vacuum evaporation of palladium through a shadow mask. Typical thickness of the detector was 2 mm. Spectrometric performance of the TlBr detectors was tested by irradiating them with {sup 241}Am (59.5 keV), {sup 57}Co (122 keV) and {sup 137}Cs (662 keV) gamma-ray sources at temperature of -20 deg. C. Energy resolutions (FWHM) were measured to be 4.0, 6.0 and 9.7 keV for 59.5, 122 and 662 keV gamma-rays, respectively.

  1. Semiconductor detector physics

    International Nuclear Information System (INIS)

    Equer, B.

    1987-01-01

    Comprehension of semiconductor detectors follows comprehension of some elements of solid state physics. They are recalled here, limited to the necessary physical principles, that is to say the conductivity. P-n and MIS junctions are discussed in view of their use in detection. Material and structure (MOS, p-n, multilayer, ..) are also reviewed [fr

  2. CdTe hybrid pixel detector for imaging with thermal neutrons

    Czech Academy of Sciences Publication Activity Database

    Jakůbek, J.; Mettivier, G.; Montesi, M.C.; Pospíšil, S.; Russo, P.; Vacík, Jiří

    2006-01-01

    Roč. 563, č. 1 (2006), s. 238-241 ISSN 0168-9002 R&D Pro jects: GA MŠk 1P04LA211 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutronography * pixel detector * semiconductor detector Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.185, year: 2006

  3. Mercuric iodide semiconductor detectors encapsulated in polymeric resin

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Joao F. Trencher; Santos, Robinson A. dos; Ferraz, Caue de M.; Oliveira, Adriano S.; Velo, Alexandre F.; Mesquita, Carlos H. de; Hamada, Margarida M., E-mail: mmhamada@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Disch, Christian; Fiederle, Michael [Albert-Ludwigs Universität Freiburg - UniFreibrug, Freiburg Materials Research Center - FMF, Freiburg (Germany)

    2015-07-01

    The development of new semiconductor radiation detectors always finds many setback factors, such as: high concentration of impurities in the start materials, poor long term stability, the surface oxidation and other difficulties discussed extensively in the literature, that limit their use. In this work was studied, the application of a coating resin on HgI2 detectors, in order to protect the semiconductor crystal reactions from atmospheric gases and to isolate electrically the surface of the crystals. Four polymeric resins were analyzed: Resin 1: 50% - 100%Heptane, 10% - 25% methylcyclohexane, <1% cyclohexane; Resin 2: 25% - 50% ethanol, 25% - 50% acetone, <2,5% ethylacetate; Resin 3: 50% - 100% methylacetate, 5% - 10% n-butylacetate; Resin 4: 50% - 100% ethyl-2-cyanacrylat. The influence of the polymeric resin type used on the spectroscopic performance of the HgI{sub 2} semiconductor detector is, clearly, demonstrated. The better result was found for the detector encapsulated with Resin 3. An increase of up to 26 times at the stability time was observed for the detectors encapsulated compared to that non-encapsulated detector. (author)

  4. 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...... of the responsivity (2–3 A/W in the 1–3 THz-frequency band) range up to several percents of the quantum efficiency e/[h-bar] omega of an ideal superconductor tunnel junction detector. Properly designed semiconductor superlattice detectors may thus demonstrate better room temperature THz-photon responsivity than...

  5. CdTe in photoconductive applications. Fast detector for metrology and X-ray imaging

    International Nuclear Information System (INIS)

    Cuzin, M.

    1991-01-01

    Operating as a photoconductor, the sensitivity and the impulse response of semi-insulating materials greatly depend on the excitation duration compared to electron and hole lifetimes. The requirement of ohmic contact is shortly discussed. Before developing picosecond measurements with integrated autocorrelation system, this paper explains high energy industrial tomographic application with large CdTe detectors (25x15x0.9 mm 3 ). The excitation is typically μs range. X-ray flash radiography, with 10 ns burst, is in an intermediate time domain where excitation is similar to electron life-time. In laser fusion experiment excitation is in the range of 50 ps and we develop photoconductive devices able to study very high speed X-ray emission time behaviour. Thin polycristalline MOCVD CdTe films with picosecond response are suitable to perform optical correlation measurements of single shot pulses with a very large bandwidth (- 50 GHz)

  6. Measurements of low noise 64 channel counting ASIC for Si and CdTe strip detectors

    International Nuclear Information System (INIS)

    Kachel, M; Grybos, P; Szczygiel, R; Takeyoshi, T

    2011-01-01

    We present the design and performance of a 64-channel ASIC called SXDR64. The circuit is intended to work with DC coupled CdTe detectors as well as with standard AC coupled Si detectors. A single channel of the ASIC consists of a charge sensitive amplifier with a pole-zero cancellation circuit, a 4 th order programmable shaper, a base-line restorer and two independent discriminators with 20-bit counters equipped with RAM. The circuit is able to operate correctly with both polarities of the input signal and the detectors leakage current in a few nA range, with the average rate of input pulses up to 1 Mcps.

  7. Front-end electronics for multichannel semiconductor detector systems

    CERN Document Server

    Grybos, P

    2010-01-01

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

  8. Radiation damage in semiconductor detectors

    International Nuclear Information System (INIS)

    Kraner, H.W.

    1981-12-01

    A survey is presented of the important damage-producing interactions in semiconductor detectors and estimates of defect numbers are made for MeV protons, neutrons and electrons. Damage effects of fast neutrons in germanium gamma ray spectrometers are given in some detail. General effects in silicon detectors are discussed and damage constants and their relationship to leakage current is introduced

  9. Semiconductor neutron detectors based on new types of materials

    International Nuclear Information System (INIS)

    Pochet, T.; Foulon, F.

    1993-01-01

    Neutron detection in hostile environments such as nuclear reactors has been performed using a new kind of semiconductor detector. So far, crystalline semiconductor detectors are not used in nuclear reactor instrumentation because of their sensitivity to radiation damage. For doses in excess of a few tens of kilo rads, radiation induced lattice defects produce a strong loss in the standard semiconductor detector performances. In the last few years, new semiconductor materials having amorphous or polycrystalline structures such as silicon, silicon carbide or CVD diamond, became available. These semiconductors, produced by Chemical Vapor Deposition, come in the form of thin layers being typically a few tens of micron thick. Their crystalline structure is particularly resistant to radiation damage up to a few Mrads but prevent the material use in spectrometry measurements. Nevertheless, these detectors, working in a counting mode, are suitable for the detection of alpha particles produced by the neutron capture reaction with boron. Such thin film detectors have a very poor sensitivity to γ-ray background. Furthermore, they are easier and cheaper to implement than current neutron gas counters. Preliminary results obtained with diamond and amorphous silicon diodes exposed to α particles are presented. (authors). 7 figs., 3 tabs., 11 refs

  10. Current simulation of symmetric contacts on CdTe

    International Nuclear Information System (INIS)

    Ruzin, A.

    2011-01-01

    This article presents the calculated current-voltage characteristics of symmetric Metal-Semiconductor-Metal configurations for Schottky, Ohmic, and injecting-Ohmic contacts on high resistivity CdTe. The results clearly demonstrate that in the wide band-gap, semi-insulating semiconductors, such as high resistivity CdTe, the linearity of the I-V curves cannot be considered a proof of the ohmicity of the contacts. It is shown that the linear I-V curves are expected for a wide range of contact barriers. Furthermore, the slope of these linear curves is governed by the barrier height, rather than the bulk doping concentration. Therefore the deduction of bulk's resistivity from the I-V curves may be false.

  11. Current simulation of symmetric contacts on CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Ruzin, A., E-mail: aruzin@post.tau.ac.il [School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, 69978 Tel Aviv (Israel)

    2011-12-01

    This article presents the calculated current-voltage characteristics of symmetric Metal-Semiconductor-Metal configurations for Schottky, Ohmic, and injecting-Ohmic contacts on high resistivity CdTe. The results clearly demonstrate that in the wide band-gap, semi-insulating semiconductors, such as high resistivity CdTe, the linearity of the I-V curves cannot be considered a proof of the ohmicity of the contacts. It is shown that the linear I-V curves are expected for a wide range of contact barriers. Furthermore, the slope of these linear curves is governed by the barrier height, rather than the bulk doping concentration. Therefore the deduction of bulk's resistivity from the I-V curves may be false.

  12. Production of CdTe Semiconductor Thin Films by Electrodeposition Technique for Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Ahmet PEKSÖZ

    2016-08-01

    Full Text Available Electro-deposited cadmium tellurite (CuTe thin film was grown onto ITO-coated glass substrate for 120 seconds at the room temperature and a constant cathodic potential of -0.85 V. Deposition solution was prepared from cadmium chloride (CdCl2, sodium tellurite (Na2TeO3 and pure water. The pH value of the deposition solution was adjusted to 2.0 by adding HCl. The EDX analysis shows that the film has 52% Cd and 48% Te elemental compositions. Film thickness was found to be 140 nm. The CdTe thin film exhibits p-type semiconductor character, and has an energy bandgap of 1.47 eV. 

  13. Performance of semiconductor radiation sensors for simple and low-cost radiation detector

    International Nuclear Information System (INIS)

    Tanimura, Yoshihiko; Birumachi, Atsushi; Yoshida, Makoto; Watanabe, Tamaki

    2008-01-01

    In order to develop a simple but reliable radiation detector for the general public, photon detection performances of radiation sensors have been studied in photon calibration fields and by Monte Carlo simulations. A silicon p-i-n photodiode and a CdTe detector were selected for the low cost sensors. Their energy responses to ambient dose equivalent H * (10) were evaluated over the energy range from 60 keV to 2 MeV. The response of the CdTe decreases markedly with increasing photon energy. On the other hand, the photodiode has the advantage of almost flat response above 150 keV. The sensitivities of these sensors are 4 to 6 cpm for the natural radiation. Detection limits of the radiation level are low enough to know the extreme increase of radiation due to emergency situations of nuclear power plants, fuel treatment facilities and so on. (author)

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

    Science.gov (United States)

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

    2016-05-01

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

  15. IDeF-X ECLAIRs: A CMOS ASIC for the Readout of CdTe and CdZnTe Detectors for High Resolution Spectroscopy

    International Nuclear Information System (INIS)

    Gevin, O.; Baron, P.; Coppolani, X.; Delagnes, E.; Lugiez, F.; Daly, F.; Limousin, O.; Meuris, A.; Pinsard, F.; Renaud, D.

    2009-01-01

    The very last member of the IDeF-X ASIC family is presented: IDeF-X ECLAIRs is a 32-channel front end ASIC designed for the readout of Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CdZnTe) Detectors. Thanks to its noise performance (Equivalent Noise Charge floor of 33 e - rms) and to its radiation hardened design (Single Event Latch-up Linear Energy Transfer threshold of 56 MeV.cm 2 .mg -1 ), the chip is well suited for soft X-rays energy discrimination and high energy resolution, 'space proof', hard X-ray spectroscopy. We measured an energy low threshold of less than 4 keV with a 10 pF input capacitor and a minimal reachable sensitivity of the Equivalent Noise Charge (ENC) to input capacitance of less than 7e - /pF obtained with a 6 μs peak time. IDeF-X ECLAIRs will be used for the readout of 6400 CdTe Schottky mono-pixel detectors of the 2D coded mask imaging telescope ECLAIRs aboard the SVOM satellite. IDeF-X ECLAIRs (or IDeF-X V2) has also been designed for the readout of a pixelated CdTe detector in the miniature spectro-imager prototype Caliste 256 that is currently foreseen for the high energy detector module of the Simbol-X mission. (authors)

  16. IDeF-X ECLAIRs: A CMOS ASIC for the Readout of CdTe and CdZnTe Detectors for High Resolution Spectroscopy

    Science.gov (United States)

    Gevin, Olivier; Baron, Pascal; Coppolani, Xavier; Daly, FranÇois; Delagnes, Eric; Limousin, Olivier; Lugiez, Francis; Meuris, Aline; Pinsard, FrÉdÉric; Renaud, Diana

    2009-08-01

    The very last member of the IDeF-X ASIC family is presented: IDeF-X ECLAIRs is a 32-channel front end ASIC designed for the readout of Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CdZnTe) Detectors. Thanks to its noise performance (Equivalent Noise Charge floor of 33 e- rms) and to its radiation hardened design (Single Event Latchup Linear Energy Transfer threshold of 56 MeV.cm2.mg-1), the chip is well suited for soft X-rays energy discrimination and high energy resolution, ldquospace proof,rdquo hard X-ray spectroscopy. We measured an energy low threshold of less than 4 keV with a 10 pF input capacitor and a minimal reachable sensitivity of the Equivalent Noise Charge (ENC) to input capacitance of less than 7 e-/pF obtained with a 6 mus peak time. IDeF-X ECLAIRs will be used for the readout of 6400 CdTe Schottky monopixel detectors of the 2D coded mask imaging telescope ECLAIRs aboard the SVOM satellite. IDeF-X ECLAIRs (or IDeF-X V2) has also been designed for the readout of a pixelated CdTe detector in the miniature spectro-imager prototype Caliste 256 that is currently foreseen for the high energy detector module of the Simbol-X mission.

  17. CdTe and Cd sub 1 sub - sub x Zn sub x Te for nuclear detectors: facts and fictions

    CERN Document Server

    Fougeres, P; Hageali, M; Koebel, J M; Regal, R

    1999-01-01

    Both CdTe and Cd sub 1 sub - sub x Zn sub x Te (CZT) can be considered from their physical properties as very good materials for room temperature X- and gamma-rays detection. However, despite years of intense material research, no significant advance has been made to help one to choose between both semiconductors. This paper reviews a few facts about CdTe and CZT to attempt to draw a real comparison between both. THM-CdTe and HPB-CZT have been grown and characterized in Strasbourg. Crystal growth, alloying effects, transport properties and defects are reviewed on the basis of our results and the published ones. The results show that it is still very difficult to claim which one is the best.

  18. Characterization of CdTe and (CdZn)Te detectors with different metal contacts

    Science.gov (United States)

    Pekárek, J.; Belas, E.; Grill, R.; Uxa, Å.; James, R. B.

    2013-09-01

    In the present work we studied an influence of different types of surface etching and surface passivation of high resistivity CdZnTe-based semiconductor detector material. The aim was to find the optimal conditions to improve the properties of metal-semiconductor contact. The main effort was to reduce the leakage current and thus get better X-ray and gamma-ray spectrum, i.e. to create a detector operating at room temperature based on this semiconductor material with sufficient energy resolution and the maximum charge collection efficiency. Individual surface treatments were characterized by I-V characteristics, spectral analysis and by determination of the profile of the internal electric field.

  19. Semiconductor detectors in the low countries

    International Nuclear Information System (INIS)

    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 ∼10 -12 s, which decay on sub-millimeter scale. The intensive activity in silicon detector R and D culminated in 1991 in the construction of fine-grained 2D monolithic and hybrid pixel detectors that incorporate sophisticated electronic functions in each microscopic detection element, with typical dimensions of 25-100 μm. Besides being a powerful high intensity tracker for particle physics, this device can also be designed as a new X-ray imager, which allows selective counting of individual photons in each pixel at MHz frequency

  20. Medipix2 based CdTe microprobe for dental imaging

    International Nuclear Information System (INIS)

    Vykydal, Z; Jakubek, J; Fauler, A; Fiederle, M; Zwerger, A; Svestkova, M

    2011-01-01

    Medical imaging devices and techniques are demanded to provide high resolution and low dose images of samples or patients. Hybrid semiconductor single photon counting devices together with suitable sensor materials and advanced techniques of image reconstruction fulfil these requirements. In particular cases such as the direct observation of dental implants also the size of the imaging device itself plays a critical role. This work presents the comparison of 2D radiographs of tooth provided by a standard commercial dental imaging system (Gendex 765DC X-ray tube with VisualiX scintillation detector) and two Medipix2 USB Lite detectors one equipped with a Si sensor (300 μm thick) and one with a CdTe sensor (1 mm thick). Single photon counting capability of the Medipix2 device allows virtually unlimited dynamic range of the images and thus increases the contrast significantly. The dimensions of the whole USB Lite device are only 15 mm × 60 mm of which 25% consists of the sensitive area. Detector of this compact size can be used directly inside the patients' mouth.

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

    International Nuclear Information System (INIS)

    Paschoal, Arquimedes J.A.; Leite, Adolfo M.B.; Nazzre, Fabio V.B.; Santos, Luiz A.P.

    2007-01-01

    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)

  2. An analytical X-ray CdTe detector response matrix for incomplete charge collection correction for photon energies up to 300 keV

    Science.gov (United States)

    Kurková, Dana; Judas, Libor

    2018-05-01

    Gamma and X-ray energy spectra measured with semiconductor detectors suffer from various distortions, one of them being so-called "tailing" caused by an incomplete charge collection. Using the Hecht equation, a response matrix of size 321 × 321 was constructed which was used to correct the effect of incomplete charge collection. The correction matrix was constructed analytically for an arbitrary energy bin and the size of the energy bin thus defines the width of the spectral window. The correction matrix can be applied separately from other possible spectral corrections or it can be incorporated into an already existing response matrix of the detector. The correction was tested and its adjustable parameters were optimized on the line spectra of 57Co measured with a cadmium telluride (CdTe) detector in a spectral range from 0 up to 160 keV. The best results were obtained when the values of the free path of holes were spread over a range from 0.4 to 1.0 cm and weighted by a Gauss function. The model with the optimized parameter values was then used to correct the line spectra of 152Eu in a spectral range from 0 up to 530 keV. An improvement in the energy resolution at full width at half maximum from 2.40 % ± 0.28 % to 0.96 % ± 0.28 % was achieved at 344.27 keV. Spectra of "narrow spectrum series" beams, N120, N150, N200, N250 and N300, generated with tube voltages of 120 kV, 150 kV, 200 kV, 250 kV and 300 kV respectively, and measured with the CdTe detector, were corrected in the spectral range from 0 to 160 keV (N120 and N150) and from 0 to 530 keV (N200, N250, N300). All the measured spectra correspond both qualitatively and quantitatively to the available reference data after the correction. To obtain better correspondence between N150, N200, N250 and N300 spectra and the reference data, lower values of the free paths of holes (range from 0.16 to 0.65 cm) were used for X-ray spectra correction, which suggests energy dependence of the phenomenon.

  3. CdTe and CdZnTe detectors behavior in X-ray computed tomography conditions

    CERN Document Server

    Ricq, S; Garcin, M

    2000-01-01

    The application of CdTe and CdZnTe 2D array detectors for medical X-ray Computed Tomography (XCT) is investigated. Different metallic electrodes have been deposited on High-Pressure Bridgman Method CdZnTe and on Traveling Heater Method CdTe:Cl. These detectors are exposed to X-rays in the CT irradiation conditions and are characterized experimentally in current mode. Detectors performances such as sensitivity and response speed are studied. They are correlated with charge trapping and de-trapping. The trapped carrier space charges may influence the injection from the electrodes. This enables one to get information on the nature of the predominant levels involved. The performances achieved are encouraging: dynamic ranges higher than 4 decades and current decreases of 3 decades in 4 ms after X-ray beam cut-off are obtained. Nevertheless, these detectors are still limited by high trap densities responsible for the memory effect that makes them unsuitable for XCT.

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

    Energy Technology Data Exchange (ETDEWEB)

    Smith, L.; Murphy, J.W. [Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Kim, J. [Korean Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of); Rozhdestvenskyy, S.; Mejia, I. [Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Park, H. [Korean Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of); Allee, D.R. [Flexible Display Center, Arizona State University, Phoenix, AZ 85284 (United States); Quevedo-Lopez, M. [Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Gnade, B., E-mail: beg031000@utdallas.edu [Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States)

    2016-12-01

    Solid-state neutron detectors offer an alternative to {sup 3}He 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{sup −6} gamma-ray efficiency.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-15

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

  6. 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.

  7. 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.

  8. Studies and development of a readout ASIC for pixelated CdTe detectors for space applications

    International Nuclear Information System (INIS)

    Michalowska, A.

    2013-01-01

    The work presented in this thesis is part of a project where a new instrument is developed: a camera for hard X-rays imaging spectroscopy. It is dedicated to fundamental research for observations in astrophysics, at wavelengths which can only be observed using space-borne instruments. In this domain the spectroscopic accuracy as well as the imaging details are of high importance. This work has been realized at CEA/IRFU (Institut de Recherche sur les lois Fondamentales de l'Univers), which has a long-standing and successful experience in instruments for high energy physics and space physics instrumentation. The objective of this thesis is the design of the readout electronics for a pixelated CdTe detector, suitable for a stacked assembly. The principal parameters of this integrated circuit are a very low noise for reaching a good accuracy in X-ray energy measurement, very low power consumption, a critical parameter in space-borne applications, and a small dead area for the full system combining the detector and the readout electronics. In this work I have studied the limits of these three parameters in order to optimize the circuit. In terms of the spectral resolution, two categories of noise had to be distinguished to determine the final performance. The first is the Fano noise limit, related to detector interaction statistics, which cannot be eliminated. The second is the electronic noise, also unavoidable; however it can be minimized through optimization of the detection chain. Within the detector, establishing a small pixel pitch of 300 μm reduces the input capacitance and the dark current. This limits the effects of the electronic noise. Also in order to limit the input capacitance the future camera is designed as a stacked assembly of the detector with the readout ASIC. This allows to reach extremely good input parameters seen by the readout electronics: a capacitance in range of 0.3 pF-1 pF and a dark current below 5 pA. In the frame of this thesis I have

  9. Characterization of electroless Au, Pt and Pd contacts on CdTe and ZnTe by RBS and SIMS techniques

    Energy Technology Data Exchange (ETDEWEB)

    Roumie, M. E-mail: mroumie@cnrs.edu.lb; Hageali, M.; Zahraman, K.; Nsouli, B.; Younes, G

    2004-06-01

    Rutherford backscattering spectrometry (RBS) was applied to characterize Au, Pt and Pd contacts on II-VI semiconductor materials, CdTe and ZnTe, used as nuclear detectors. Electroless thin film depositions were prepared by changing the concentration of the reaction solution. Contrary to the deposition reaction time, it was observed that the amount of solution dilution degree had a considerable effect on increasing the thickness of the metal layer. Furthermore, PICTS electrical measurements confirmed the depth profile analysis performed by RBS and SIMS.

  10. Exploration of Pixelated detectors for double beta decay searches within the COBRA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Schwenke, M., E-mail: schwenke@asp.tu-dresden.de [Institut fuer Kern- und Teilchenphysik, Technische Universitaet Dresden, Zellescher Weg 19, 01069 Dresden (Germany); Zuber, K.; Janutta, B. [Institut fuer Kern- und Teilchenphysik, Technische Universitaet Dresden, Zellescher Weg 19, 01069 Dresden (Germany); He, Z.; Zeng, F. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Anton, G.; Michel, T.; Durst, J.; Lueck, F.; Gleixner, T. [Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Goessling, C.; Schulz, O.; Koettig, T. [Technische Universitaet Dortmund, Physik E IV, 44221 Dortmund (Germany); Krawczynski, H.; Martin, J. [Department of Physics, Washington University in St. Louis, Campus Box 1105, One Brookings Drive, St. Louis, MO 63130-4899 (United States); Stekl, I.; Cermak, P. [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 128 00 Prague (Czech Republic)

    2011-09-11

    The aim of the COBRA experiment is the search for neutrinoless double beta decay events in Cadmium Zinc Telluride (CdZnTe) room temperature semiconductor detectors. The development of pixelated detectors provides the potential for clear event identification and thus major background reduction. The tracking option of a semiconductor is a unique approach in this field. For initial studies, several possible detector systems are considered with a special regard for low background applications: the large volume system Polaris with a pixelated CdZnTe sensor, Timepix detectors with Si and enriched CdTe sensor material and a CdZnTe pixel system developed at the Washington University in St. Louis, USA. For all detector systems first experimental background measurements taken at underground laboratories (Gran Sasso Underground Laboratory in Italy, LNGS and the Niederniveau Messlabor Felsenkeller in Dresden, Germany) and additionally for the Timepix detectors simulation results are presented.

  11. Induced Charge Fluctuations in Semiconductor Detectors with a Cylindrical Geometry

    Science.gov (United States)

    Samedov, Victor V.

    2018-01-01

    Now, compound semiconductors are very appealing for hard X-ray room-temperature detectors for medical and astrophysical applications. Despite the attractive properties of compound semiconductors, such as high atomic number, high density, wide band gap, low chemical reactivity and long-term stability, poor hole and electron mobility-lifetime products degrade the energy resolution of these detectors. The main objective of the present study is in development of a mathematical model of the process of the charge induction in a cylindrical geometry with accounting for the charge carrier trapping. The formulae for the moments of the distribution function of the induced charge and the formulae for the mean amplitude and the variance of the signal at the output of the semiconductor detector with a cylindrical geometry were derived. It was shown that the power series expansions of the detector amplitude and the variance in terms of the inverse bias voltage allow determining the Fano factor, electron mobility lifetime product, and the nonuniformity level of the trap density of the semiconductor material.

  12. Fabrication of prototypes of Ge(li) semiconductor detector

    International Nuclear Information System (INIS)

    Santos, W.M.S.; Marti, G.V.; Rizzo, P.; Barros, S. de.

    1987-01-01

    The fabrication process of Ge(Li) semiconductor detector prototypes, from specific chemical treatments of doped monocrystal with receptor impurities (p + semicondutor) is presented. The detector characteristics, such as resulotion and operation tension are shown. (M.C.K.) [pt

  13. Semiconductor radiation detector

    Science.gov (United States)

    Bell, Zane W.; Burger, Arnold

    2010-03-30

    A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

  14. 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...

  15. Development of a 32-detector CdTe matrix for the SVOM ECLAIRs X/Gamma camera: Preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Lacombe, K., E-mail: karine.lacombe@irap.omp.eu [Université de Toulouse, Toulouse (France); UPS-OMP, Toulouse (France); IRAP CNRS, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Nasser, G.; Amoros, C.; Atteia, J.-L.; Barret, D. [Université de Toulouse, Toulouse (France); UPS-OMP, Toulouse (France); IRAP CNRS, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Billot, M. [CNES, 18 Av. Edouard Belin, 31 401 Toulouse Cedex 9 (France); Cordier, B.; Gevin, O. [CEA, IRFU, 91191 Gif-sur-Yvette (France); Godet, O. [Université de Toulouse, Toulouse (France); UPS-OMP, Toulouse (France); IRAP CNRS, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Gonzalez, F. [CNES, 18 Av. Edouard Belin, 31 401 Toulouse Cedex 9 (France); Houret, B.; Landé, J. [Université de Toulouse, Toulouse (France); UPS-OMP, Toulouse (France); IRAP CNRS, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Lugiez, F. [CEA, IRFU, 91191 Gif-sur-Yvette (France); Mandrou, P.; Martin, J.-A.; Marty, W. [Université de Toulouse, Toulouse (France); UPS-OMP, Toulouse (France); IRAP CNRS, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Mercier, K. [CNES, 18 Av. Edouard Belin, 31 401 Toulouse Cedex 9 (France); Pons, R.; Rambaud, D.; Ramon, P. [Université de Toulouse, Toulouse (France); UPS-OMP, Toulouse (France); IRAP CNRS, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); and others

    2013-12-21

    ECLAIRs, a 2D coded-mask imaging telescope on the Sino-French SVOM space mission, will detect and locate gamma-ray bursts (GRBs) between 4 and 150 keV. The detector array is an assembly of 6400 Schottky CdTe detectors of size 4×4×1 mm{sup 3}, biased from −100 V to −600 V and operated at −20 °C to minimize the leakage current and maximize the polarization time. The remarkable low-energy threshold is achieved through various steps: an extensive detectors selection, a low-noise 32 channels ASIC study, and the design of an innovative detection module called XRDPIX formed by a thick film ceramic holding 32 detectors, a high voltage grid and an HTCC substrate housing the ASIC within a hermetic cavity. In this paper, we describe the XRDPIX module and explain the results of first tests to measure the linearity and compare the sources of noise, such as leakage currents and the Equivalent Noise Charge (ENC) measured on ASIC Ceramics. We confront these values with the energy threshold and spectral resolution made with dedicated test benches. Finally, we present the superposition of 32 calibrated spectra of one XRDPIX module, showing the excellent homogeneity of the 32 detectors and the achievement of a detection threshold at 4 keV over the entire module. -- Highlights: •We develop X and gamma rays detection modules to shape a space telescope. •The main goal of 4 keV threshold is reached thanks to a new hybrid based on CdTe. •Great spectral performance depends on low equivalent noise charge of ASIC on ceramics. •We study the good linearity of the calibration curve below the 16 keV energy. •An outgassing stage will decrease the leakage current of detectors glued on ceramics.

  16. Solid-state cadmium telluride radiation detector

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, Yoji; Kitamoto, Hisashi; Hosomatsu, Haruo

    1984-09-01

    The growth of CdTe single crystal and its application to CdTe detector array was studied for X-ray computed tomography (XCT) equipment. A p-type CdTe single crystal with 10/sup 4/ ohm.cm specific resistivity was grown in a quartz ampoule under vapor pressure control of Cd in a vertical Bridgman furnace. An 18-element detector array was fabricated with this single crystal. The detector was operated with no bias and the sensitivity was confirmed to be between 2.8 x 10/sup -12/ and 14 x 10/sup -12/ A.h/(R.mm/sup 2/). Commercial CdTe single crystal was used to manufacture as 560-element detector array for XCT. Results show that CdTe detector is sensitive, linear and has high resolution.

  17. Leakage current measurements on pixelated CdZnTe detectors

    NARCIS (Netherlands)

    Dirks, B.; 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

  18. 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...

  19. Ellipsometry of rough CdTe(211)B-Ge(211) surfaces grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Badano, Giacomo; Ballet, Philippe; Zanatta, Jean-Paul; Baudry, Xavier; Million, Alain; Garland, James W.

    2006-01-01

    The effect of surface roughness on the ellipsometric response of semiconductor surfaces is investigated. CdTe(211)B layers were grown on Ge(211) by molecular beam epitaxy using less than optimal growth conditions to enhance the formation of surface roughness. Their optical properties, measured by rotating-compensator ellipsometry, showed small but significant sample-to-sample differences not explainable in terms of nanometer-scale roughness. A critical-point analysis established that the critical-point structure of the dielectric function was the same for all samples. This result suggested that the observed sample-to-sample variations were due to macroscopic roughness, which scatters off-specular light into the detector, thereby causing errors. We introduced tentative corrections for off-specular reflection that fitted the observed differences and thus supported the idea that off-specular reflection was responsible for the observed differences. These results were obtained using CdTe but are easily extensible to other rough opaque materials

  20. 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.

  1. 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.

    1994-12-31

    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.

  2. Energy resolution and throughput of a new real time digital pulse processing system for x-ray and gamma ray semiconductor detectors

    International Nuclear Information System (INIS)

    Abbene, L; Gerardi, G; Raso, G; Brai, M; Principato, F; Basile, S

    2013-01-01

    New generation spectroscopy systems have advanced towards digital pulse processing (DPP) approaches. DPP systems, based on direct digitizing and processing of detector signals, have recently been favoured over analog pulse processing electronics, ensuring higher flexibility, stability, lower dead time, higher throughput and better spectroscopic performance. In this work, we present the performance of a new real time DPP system for X-ray and gamma ray semiconductor detectors. The system is based on a commercial digitizer equipped with a custom DPP firmware, developed by our group, for on-line pulse shape and height analysis. X-ray and gamma ray spectra measurements with cadmium telluride (CdTe) and germanium (Ge) detectors, coupled to resistive-feedback preamplifiers, highlight the excellent performance of the system both at low and high rate environments (up to 800 kcps). A comparison with a conventional analog electronics showed the better high-rate capabilities of the digital approach, in terms of energy resolution and throughput. These results make the proposed DPP system a very attractive tool for both laboratory research and for the development of advanced detection systems for high-rate-resolution spectroscopic imaging, recently proposed in diagnostic medicine, industrial imaging and security screening

  3. Electron Beam Induced Radiation Damage of the Semiconductor Radiation Detector based on Silicon

    International Nuclear Information System (INIS)

    Kim, Han Soo; Kim, Yong Kyun; Park, Se Hwan; Haa, Jang Ho; Kang, Sang Mook; Chung, Chong Eun; Cho, Seung Yeon; Park, Ji Hyun; Yoon, Tae Hyung

    2005-01-01

    A Silicon Surface Barrier (SSB) semiconductor detector which is generally used to detect a charged particle such as an alpha particle was developed. The performance of the developed SSB semiconductor detector was measured with an I-V curve and an alpha spectrum. The response for an alpha particle was measured by Pu-238 sources. A SSB semiconductor detector was irradiated firstly at 30sec, at 30μA and secondly 40sec, 40μA with a 2MeV pulsed electron beam generator in KAERI. And the electron beam induced radiation damage of a homemade SSB detector and the commercially available PIN photodiode were investigated. An annealing effect of the damaged SSB and PIN diode detector were also investigated using a Rapid Thermal Annealing (RTA). This data may assist in designing the silicon based semiconductor radiation detector when it is operated in a high radiation field such as space or a nuclear power plant

  4. Measurement of neutron flux by semiconductor detector; Merenje raspodele neutronskog fluksa poluprovodnickim detektorom

    Energy Technology Data Exchange (ETDEWEB)

    Obradovic, D; Bosevski, T [The Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

    1965-07-01

    Using semiconductor detectors for measuring the neutron flux distribution is considered suitable and faster than using activation foils. Results of radial neutron flux distribution obtained by semiconductor detectors are presented.

  5. Superconducting detectors for semiconductor quantum photonics

    International Nuclear Information System (INIS)

    Reithmaier, Guenther M.

    2015-01-01

    In this thesis we present the first successful on-chip detection of quantum light, thereby demonstrating the monolithic integration of superconducting single photon detectors with individually addressable semiconductor quantum dots in a prototypical quantum photonic circuit. Therefore, we optimized both the deposition of high quality superconducting NbN thin films on GaAs substrates and the fabrication of superconducting detectors and successfully integrated these novel devices with GaAs/AlGaAs ridge waveguides loaded with self-assembled InGaAs quantum dots.

  6. Parallel of semi-empirical results simulated by MCNP of X-ray spectra with a semiconductor

    International Nuclear Information System (INIS)

    Santos, L.R.; Vivolo, V.; Potiens, M.P.A.; Navarro, M.V.T.; Santos, W.S.

    2016-01-01

    The aim of this study was to use the MCNPX radiation transport code to simulate X-ray spectra generated by a constant voltage system in a CdTe semiconductor detector. As part of the validation process, we obtained a series of experimental spectra. Comparatively, in all cases there is a good correlation between the two spectra. There were no statistically significant differences between the experimental results with the simulated. (author)

  7. Stability issues of high-energy resolution diode type CdTe nuclear radiation detectors in a long-term operation

    CERN Document Server

    Niraula, M; Aoki, T; Tomita, Y; Hatanaka, Y

    2002-01-01

    High-energy resolution diode type CdTe detectors were fabricated by growing an n-type epitaxial layer on high resistivity p-like crystal wafers, and their stability issues during a long-term operation were studied. Room temperature stability of the detectors was not good at low operating biases of around 200 V. However, it could be improved significantly by operating them at higher biases under full depletion conditions. On the other hand, detectors exhibited excellent stability by cooling them slightly below room temperature down to 0 deg. C. The effect of this low level of cooling on detector stability was found to be more significant than that of applying high biases at room temperature. By using the detector type presented here, stable operation could be obtained at moderate operating voltages of around 400 V and with a modest degree of cooling.

  8. Measurement of ionising radiation semiconductor detectors: a review

    International Nuclear Information System (INIS)

    Aussel, J.P.

    1986-06-01

    Manufacturing techniques for nuclear detectors using semiconductors are constantly advancing, and a large range of models with different specificities and characteristics are available. After a theoretical reminder, this report describes the main types of detectors, their working and their preferential use. A comparative table guides the neophyte reader in his choice [fr

  9. Solid state semiconductor detectorized survey meter

    International Nuclear Information System (INIS)

    Okamoto, Eisuke; Nagase, Yoshiyuki; Furuhashi, Masato

    1987-01-01

    Survey meters are used for measurement of gamma ray dose rate of the space and the surface contamination dencity that the atomic energy plant and the radiation facility etc. We have recently developed semiconductor type survey meter (Commercial name: Compact Survey Meter). This survey meter is a small-sized dose rate meter with excellent function. The special features are using semiconductor type detector which we have developed by our own technique, stablar wide range than the old type, long life, and easy to carry. Now we introduce the efficiency and the function of the survey meter. (author)

  10. 1-D position sensitive single carrier semiconductor detectors

    International Nuclear Information System (INIS)

    Zhong He; Knoll, G.F.; Wehe, D.K.; Rojeski, R.; Mastrangelo, C.H.; Hammig, M.; Barrett, C.; Uritani, A.

    1996-01-01

    A single polarity charge sensing method has been studied using coplanar electrodes on 5 mm cubes of CdZnTe γ-ray detectors. This method can ameliorate the hole trapping problem of room-temperature semiconductor detectors. Our experimental results confirm that the energy resolution is dramatically improved compared with that obtained using the conventional readout method, but is still about an order of magnitude worse than the theoretical limit. A method to obtain the γ-ray interaction depth between the cathode and the anode is presented here. This technique could be used to correct for the electron trapping as a function of distance from the coplanar electrodes. Experimental results showed that a position resolution of about 0.9 mm FWHM at 122 keV can be obtained. These results will be of interest in the design of higher performance room-temperature semiconductor γ-ray detectors. (orig.)

  11. 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.

  12. CCST [Center for Compound Semiconductor Technology] research briefs

    International Nuclear Information System (INIS)

    Zipperian, T.E.; Voelker, E.R.

    1989-12-01

    This paper discusses the following topics: theoretical predictions of valence and conduction band offsets in III-V semiconductors; reflectance modulation of a semiconductor superlattice optical mirror; magnetoquantum oscillations of the phonon-drag thermoelectric power in quantum wells; correlation between photoluminescence line shape and device performance of p-channel strained-layer materials; control of threading dislocations in heteroepitaxial structures; improved growth of CdTe on GaAs by patterning; role of structure threading dislocations in relaxation of highly strained single-quantum-well structures; InAlAs growth optimization using reflection mass spectrometry; nonvolatile charge storage in III-V heterostructures; optically triggered thyristor switches; InAsSb strained-layer superlattice infrared detectors with high detectivities; resonant periodic gain surface-emitting semiconductor lasers; performance advantages of strained-quantum-well lasers in AlGaAs/InGaAs; optical integrated circuit for phased-array radar antenna control; and deposition and novel device fabrication from Tl 2 Ca 2 Ba 2 Cu 3 O y thin films

  13. Excimer laser doping technique for application in an integrated CdTe imaging device

    CERN Document Server

    Mochizuki, D; Aoki, T; Tomita, Y; Nihashi, T; Hatanaka, Y

    1999-01-01

    CdTe is an attractive semiconductor material for applications in solid-state high-energy X-ray and gamma-ray imaging systems because of its high absorption coefficient, large band gap, good mobility lifetime product of holes and stability at normal atmospheric conditions. We propose a new concept for fabricating an integrated CdTe with monolithic circuit configuration for two-dimensional imaging systems suitable for medical, research or industrial applications and operation at room temperature. A new doping technique has been recently developed that employs excimer laser radiation to diffuse impurity atoms into the semiconductor. Accordingly, heavily doped n- and p-type layers with resistivities less than 1 OMEGA cm can be formed on the high resistive CdTe crystals. We have further extended this technique for doping with spatial pattern. We will present the laser doping technique and various results thus obtained. Spatially patterned doping is demonstrated and we propose the use of these doping techniques for...

  14. Radiation detectors: needs and prospects

    International Nuclear Information System (INIS)

    Armantrout, G.A.

    1981-01-01

    Important applications for x- and γ-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 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. Basic processes and scintillator and semiconductor detectors

    International Nuclear Information System (INIS)

    Bourgeois, C.

    1994-01-01

    In the following course, the interaction of heavy charged particles, electrons and Γ with matter is represented. Two types of detectors are studied, organic and inorganic scintillators and semiconductors. The signal formation is analysed. (author). 13 refs., 48 figs., 5 tabs

  16. Towards time-of-flight PET with a semiconductor detector

    Science.gov (United States)

    Ariño-Estrada, Gerard; Mitchell, Gregory S.; Kwon, Sun Il; Du, Junwei; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.; Cherry, Simon R.

    2018-02-01

    The feasibility of using Cerenkov light, generated by energetic electrons following 511 keV photon interactions in the semiconductor TlBr, to obtain fast timing information for positron emission tomography (PET) was evaluated. Due to its high refractive index, TlBr is a relatively good Cerenkov radiator and with its wide bandgap, has good optical transparency across most of the visible spectrum. Coupling an SiPM photodetector to a slab of TlBr (TlBr-SiPM) yielded a coincidence timing resolution of 620 ps FWHM between the TlBr-SiPM detector and a LFS reference detector. This value improved to 430 ps FWHM by applying a high pulse amplitude cut based on the TlBr-SiPM and reference detector signal amplitudes. These results are the best ever achieved with a semiconductor PET detector and already approach the performance required for time-of-flight. As TlBr has higher stopping power and better energy resolution than the conventional scintillation detectors currently used in PET scanners, a hybrid TlBr-SiPM detector with fast timing capability becomes an interesting option for further development.

  17. The role of contacts in semiconductor gamma radiation detectors

    International Nuclear Information System (INIS)

    Lachish, U.

    1998-01-01

    It is proposed that the operation of semiconductor gamma radiation detectors, equipped with ohmic contacts, which allow free electron flow between the contacts and bulk material, will not be sensitive to low hole mobility, hole collection efficiency, or hole trapping. Such fast-operating detectors may be readily integrated into monolithic arrays. The detection mechanism and various material aspects are discussed and compared to those of blocking contact detectors. Some suggestions for detector realization are presented. (orig.)

  18. Semiconductor detectors in current energy dispersive X-ray spectral analysis

    Energy Technology Data Exchange (ETDEWEB)

    Betin, J; Zhabin, E; Krampit, I; Smirnov, V

    1980-04-01

    A review is presented of the properties of semiconductor detectors and of the possibilities stemming therefrom of using the detectors in X-ray spectral analysis in industries, in logging, in ecology and environmental control, in medicine, etc.

  19. 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 ...

  20. Semiconductor detectors in current energy dispersive X-ray spectral analysis

    International Nuclear Information System (INIS)

    Betin, J.; Zhabin, E.; Krampit, I.; Smirnov, V.

    1980-01-01

    A review is presented of the properties of semiconductor detectors and of the possibilities stemming therefrom of using the detectors in X-ray spectral analysis in industries, in logging, in ecology and environmental control, in medicine, etc. (M.S.)

  1. A spectrometer using semi-conductor detectors; study and applications (1963)

    International Nuclear Information System (INIS)

    Roux, G.

    1963-01-01

    The low average energy, 2.5 to 3.5 eV, required to produce one hole-electron pair in a semiconductor allows an accurate measurement of the energy of the ionizing particles. A high resolution spectrometer has been built using semiconductor detectors. The limit of resolution, due to electronics associated to the detector, to the detector itself and to the source of particles is studied here. The present practical limit of resolution of the spectrometer is 1700 elementary electric charges (full width at half maximum of a ray of a spectrum) or 6 keV in terms of energy lost by a particle in a silicon detector. The physical resolution usually obtained is 20 keV (0.33 per cent) with α particles of the 212 Bi (6.087 MeV). It depends a lot of the kind of detector used. Some results, concerning the background of the detectors and limit of measurements for low energies are given. Various applications are presented: spectrometry β, spectrometry γ and X, spectrometry of mixtures of α radioactive elements, collection of α spectra. (author) [fr

  2. CdZnTe and CdTe materials for X-ray and gamma ray radiation detector applications

    International Nuclear Information System (INIS)

    Szeles, Csaba

    2004-01-01

    Good detection efficiency and high energy-resolution make Cadmium Zinc Telluride (CdZnTe) and Cadmium Telluride (CdTe) detectors attractive in many room temperature X-ray and gamma-ray detection applications such as medical and industrial imaging, industrial gauging and non-destructive testing, security and monitoring, nuclear safeguards and non-proliferation, and astrophysics. Advancement of the crystal growth and device fabrication technologies and the reduction of bulk, interface and surface defects in the devices are crucial for the widespread practical deployment of Cd 1-x Zn x Te-based detector technology. Here we review the effects of bulk, interface and surface defects on charge transport, charge transport uniformity and device performance and the progress in the crystal growth and device fabrication technologies aiming at reducing the concentration of harmful defects and improving Cd 1-x Zn x Te detector performance. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Properties of SiC semiconductor detector of fast neutrons investigated using MCNPX code

    International Nuclear Information System (INIS)

    Sedlakova, K.; Sagatova, A.; Necas, V.; Zatko, B.

    2013-01-01

    The potential of silicon carbide (SiC) for use in semiconductor nuclear radiation detectors has been long recognized. The wide bandgap of SiC (3.25 eV for 4H-SiC polytype) compared to that for more conventionally used semiconductors, such as silicon (1.12 eV) and germanium (0.67 eV), makes SiC an attractive semiconductor for use in high dose rate and high ionization nuclear environments. The present work focused on the simulation of particle transport in SiC detectors of fast neutrons using statistical analysis of Monte Carlo radiation transport code MCNPX. Its possibilities in detector design and optimization are presented.(authors)

  4. Peltier battery thermostat for semiconductor detectors

    International Nuclear Information System (INIS)

    Caini, V.

    1980-01-01

    The description is given of a Peltier battery cooling thermostat for semiconductor detectors, whose sensing element is the detector itself. A signal proportional to the leakage current is amplified and compared with a chosen reference voltage. The difference, amplified and sensed, regulates the cooling current to the Peltier battery. Special mechanical devices speed up measurement-taking. The leakage current proved to be reducible to as little as 1/1000 of that at ambient temperature and the stabilization obtained is between +-5 nA (although between +-1 nA is also feasible). Hence it is possible to use very high load resistance preamplifiers to reduce noise and to improve stability and pulse height resolution in α spectroscopy, even with a detector unsuitable for work at very low temperatures. Other applications can be foreseen. (orig.)

  5. Microelectronics used for Semiconductor Imaging Detectors

    CERN Document Server

    Heijne, Erik H M

    2010-01-01

    Semiconductor crystal technology, microelectronics developments and nuclear particle detection have been in a relation of symbiosis, all the way from the beginning. The increase of complexity in electronics chips can now be applied to obtain much more information on the incident nuclear radiation. Some basic technologies are described, in order to acquire insight in possibilities and limitations for the most recent detectors.

  6. 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.

  7. Structure of CdTe nanoparticles in glass

    Science.gov (United States)

    Hayes, T. M.; Nagpal, Swati; Persans, P. D.

    2000-03-01

    Optical long-pass wavelength filters are generally made by growing small crystallites of appropriate semiconductors in a transparent glass matrix. Depending on the semiconductor, these systems are candidates for interesting and important nonlinear optical switching applications. The structure of these nanocrystals has been shown to be a valuable indicator of the chemical and thermodynamic processes during crystallite growth and dissolution. We have used x-ray absorption spectroscopy to study the structure of the crystallites produced during heat treatment of filter glasses containing Cd and Te and producing optical absorption edges at the band gap of bulk CdTe. The results will be discussed.

  8. Study on effects of gamma-ray irradiation on TlBr semiconductor detectors

    International Nuclear Information System (INIS)

    Matsumura, Motohiro; Watanabe, Kenichi; Yamazaki, Atsushi; Uritani, Akira; Kimura, Norihisa; Nagano, Nobumichi; Hitomi, Keitaro

    2016-01-01

    Radiation hardness of thallium bromide (TlBr) semiconductor detectors to 60 Co gamma-ray irradiation was evaluated. The energy spectra and μτ products of electrons were measured to evaluate the irradiation effects. No significant degradation of spectroscopic performance of the TlBr detector for 137 Cs gamma-rays was observed up to 45 kGy irradiation. Although the μτ products of electrons in the TlBr detector slightly decreased, position of the photo-peak was stable without significant degradation after the gamma-ray irradiation. We confirmed that the TlBr semiconductor detector has a high tolerance for gamma-ray irradiation at least up to 45 kGy. (author)

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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.

  10. 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)

  11. Charge collection efficiency in a semiconductor radiation detector with a non-constant electric field

    International Nuclear Information System (INIS)

    Shah, K.S.; Lund, J.C.; Olschner, F.

    1990-01-01

    The development of improved semiconductor radiation detectors would be facilitated by a quantitative model that predicts the performance of these detectors as a function of material characteristics and device operating parameters. An accurate prediction of the pulse height spectrum from a radiation detector can be made if both the noise and the charge collection properties of the detector are understood. The noise characteristics of semiconductor radiation detectors have been extensively studied. The effect of noise can be closely simulated by convoluting the noise-free pulse height spectrum with a Gaussian function. Distortion of semiconductor detector's pulse height spectrum from charge collection effects is more complex than the effects of noise and is more difficult to predict. To compute these distortions it is necessary to know how the charge collection efficiency η varies as a function of position within the detector x. These effects are shown. This problem has been previously solved for planar detectors with a constant electric field, for the case of spherical detectors, and for coaxial detectors. In this paper the authors describe a more general solution to the charge collection problem which includes the case of a non-constant electric field in a planar geometry

  12. Characterization of paraffin based breast tissue equivalent phantom using a CdTe detector pulse height analysis.

    Science.gov (United States)

    Cubukcu, Solen; Yücel, Haluk

    2016-12-01

    In this study, paraffin was selected as a base material and mixed with different amounts of CaSO 4 ·2H 2 O and H 3 BO 3 compounds in order to mimic breast tissue. Slab phantoms were produced with suitable mixture ratios of the additives in the melted paraffin. Subsequently, these were characterized in terms of first half-value layer (HVL) in the mammographic X-ray range using a pulse-height spectroscopic analysis with a CdTe detector. Irradiations were performed in the energy range of 23-35 kV p under broad beam conditions from Mo/Mo and Mo/Rh target/filter combinations. X-ray spectra were acquired with a CdTe detector without and with phantom material interposition in increments of 1 cm thickness and then evaluated to obtain the transmission data. The net integral areas of the spectra for the slabs were used to plot the transmission curves and these curves were fitted to the Archer model function. The results obtained for the slabs were compared with those of standard mammographic phantoms such as CIRS BR series phantoms and polymethylmethacrylate plates (PMMA). From the evaluated transmission curves, the mass attenuation coefficients and HVLs of some mixtures are close to those of the commercially available standard mammography phantoms. Results indicated that when a suitable proportion of H 3 BO 3 and CaSO 4 ·2H 2 O is added to the paraffin, the resulting material may be a good candidate for a breast tissue equivalent phantom.

  13. 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.

  14. Development of a counting pixel detector for 'Digitales Roentgen'

    International Nuclear Information System (INIS)

    Lindner, M.

    2001-08-01

    The development of a single photon counting X-ray imaging detector for medical applications using hybrid pixel detectors is reported. The electronics development from the first prototype derived from detector development for particle physics experiments (ATLAS) to the imaging chip MPEC (multi picture element counters) for medical applications is described. This chip consists of 32 x 32 pixels of 200 μm x 200 μm size, each containing the complete read out electronics, i.e. an amplifier, two discriminators with adjustable thresholds and two 18-bit linear feedback shift-counters allowing energy windowing for contrast increase. Results on electronics performance are shown as well as measurements with several semiconductor materials (Si, GaAs, CdTe). Important aspects like detection efficiency, sensor homogeneity, linearity and spatial resolution are discussed. (orig.)

  15. Study on Characteristic of CdZnTe Semiconductor Detectors for Alpha Particle Measurement

    International Nuclear Information System (INIS)

    Kang, Sang Mook; Ha, Jang Ho; Kim, Yong Kyun; Park, Se Hwan; Kim, Han Soo; Chung, Chong Eun

    2005-01-01

    The last 2-3 years have seen continued effort in the development of a wide band gap room-temperature compound semiconductor devices aimed principally at photon imaging covering hard X-rays, synchrotrons, and low to medium energy gamma rays. Especially, among the semiconductor materials of a wide band gap, CdZnTe(CZT) has commonly used X-ray and gammaray detection applications because of the opportunity to achieve and excellent spectral and spatial resolution. It has recently been demonstrated that CZT can be used as an ancillary detector with the ability to detect both alpha particles and X-ray at room temperature. CZT detectors are relatively inexpensive compared with some silicon detectors, and are priced about the same as amorphous silicon and photodiodes which are routinely used for charged particle detection. In this paper, we investigated the use of the CZT semiconductor material as an alpha particles detector

  16. Study and development of new CdTe and CdZnTe detection structures for X and γ imagery

    International Nuclear Information System (INIS)

    Rosaz, M.

    1997-01-01

    The aim of this study is to show the interest of applying cadmium telluride (CdTe) for X- and γ- 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 γ- 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 γ- 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 γ- ray imaging. (author)

  17. Matrix-Assisted Laser Desorption Ionization Mass Spectrometry of Compounds Containing Carboxyl Groups Using CdTe and CuO Nanoparticles

    OpenAIRE

    Megumi Sakurai; Taro Sato; Jiawei Xu; Soichi Sato; Tatsuya Fujino

    2018-01-01

    Matrix-assisted laser desorption ionization mass spectrometry of compounds containing carboxyl groups was carried out by using semiconductor nanoparticles (CdTe and CuO) as the matrix. Salicylic acid (Sal), glucuronic acid (Glu), ibuprofen (Ibu), and tyrosine (Tyr) were ionized as deprotonated species (carboxylate anions) by using electrons ejected from CdTe after the photoexcitation. When CuO was used as the matrix, the peak intensity of Tyr became high compared with that obtained with CdTe....

  18. Industrial workshop on LASL semiconductor radiation-detector research and development

    International Nuclear Information System (INIS)

    Endebrock, M.

    1978-11-01

    An Industrial Workshop on LASL Semiconductor Radiation Detector Research and Development was held at the Los Alamos Scientific Laboratory (LASL) in the spring of 1977. The purpose was to initiate communication between our detector research and development program and industry. LASL research programs were discussed with special emphasis on detector problems. Industrial needs and capabilities in detector research and development were also presented. Questions of technology transfer were addressed. The notes presented here are meant to be informal, as were the presentations

  19. Stable room-temperature thallium bromide semiconductor radiation detectors

    Science.gov (United States)

    Datta, A.; Fiala, J.; Becla, P.; Motakef, Shariar

    2017-10-01

    Thallium bromide (TlBr) is a highly efficient ionic semiconductor with excellent radiation detection properties. However, at room temperature, TlBr devices polarize under an applied electric field. This phenomenon not only degrades the charge collection efficiency of the detectors but also promotes chemical reaction of the metal electrodes with bromine, resulting in an unstable electric field and premature failure of the device. This drawback has been crippling the TlBr semiconductor radiation detector technology over the past few decades. In this exhaustive study, this polarization phenomenon has been counteracted using innovative bias polarity switching schemes. Here the highly mobile Br- species, with an estimated electro-diffusion velocity of 10-8 cm/s, face opposing electro-migration forces during every polarity switch. This minimizes the device polarization and availability of Br- ions near the metal electrode. Our results indicate that it is possible to achieve longer device lifetimes spanning more than 17 000 h (five years of 8 × 7 operation) for planar and pixelated radiation detectors using this technique. On the other hand, at constant bias, 2500 h is the longest reported lifetime with most devices less than 1000 h. After testing several biasing switching schemes, it is concluded that the critical bias switching frequency at an applied bias of 1000 V/cm is about 17 μHz. Using this groundbreaking result, it will now be possible to deploy this highly efficient room temperature semiconductor material for field applications in homeland security, medical imaging, and physics research.

  20. Stable room-temperature thallium bromide semiconductor radiation detectors

    Directory of Open Access Journals (Sweden)

    A. Datta

    2017-10-01

    Full Text Available Thallium bromide (TlBr is a highly efficient ionic semiconductor with excellent radiation detection properties. However, at room temperature, TlBr devices polarize under an applied electric field. This phenomenon not only degrades the charge collection efficiency of the detectors but also promotes chemical reaction of the metal electrodes with bromine, resulting in an unstable electric field and premature failure of the device. This drawback has been crippling the TlBr semiconductor radiation detector technology over the past few decades. In this exhaustive study, this polarization phenomenon has been counteracted using innovative bias polarity switching schemes. Here the highly mobile Br− species, with an estimated electro-diffusion velocity of 10−8 cm/s, face opposing electro-migration forces during every polarity switch. This minimizes the device polarization and availability of Br− ions near the metal electrode. Our results indicate that it is possible to achieve longer device lifetimes spanning more than 17 000 h (five years of 8 × 7 operation for planar and pixelated radiation detectors using this technique. On the other hand, at constant bias, 2500 h is the longest reported lifetime with most devices less than 1000 h. After testing several biasing switching schemes, it is concluded that the critical bias switching frequency at an applied bias of 1000 V/cm is about 17 μHz. Using this groundbreaking result, it will now be possible to deploy this highly efficient room temperature semiconductor material for field applications in homeland security, medical imaging, and physics research.

  1. A semiconductor parameter analyzer for ionizing radiation detectors

    International Nuclear Information System (INIS)

    Santos, Luiz A.P.

    2009-01-01

    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)

  2. Dual-Energy Semiconductor Detector of X-rays and Gamma Radiation

    Directory of Open Access Journals (Sweden)

    Brodyn, M.S.

    2014-03-01

    Full Text Available Analysis of the major types of ionizing radiation detectors, their advantages and disadvantages are presented. Application of ZnSe-based semiconductor detector in high temperature environment is substantiated. Different forms of ZnSe-based detector samples and double-crystal scheme for registration of X- and gamma rays in a broad energy range were used . Based on the manufactured simulator device, the study sustains the feasibility of the gamma quanta recording by a high-resistance ZnSe-based detector operating in a perpulse mode.

  3. Study of polarization phenomena in Schottky CdTe diodes using infrared light illumination

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Goro, E-mail: gsato@astro.isas.jaxa.jp [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Fukuyama, Taro [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-0033 (Japan); Watanabe, Shin; Ikeda, Hirokazu; Ohta, Masayuki; Ishikawa, Shin' nosuke [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Takahashi, Tadayuki [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-0033 (Japan); Shiraki, Hiroyuki; Ohno, Ryoichi [ACRORAD Co., Ltd., 13-23 Suzaki, Uruma, Okinawa 904-2234 (Japan)

    2011-10-01

    Schottky CdTe diode detectors suffer from a polarization phenomenon, which is characterized by degradation of the spectral properties over time following exposure to high bias voltage. This is considered attributable to charge accumulation at deep acceptor levels. A Schottky CdTe diode was illuminated with an infrared light for a certain period during a bias operation, and two opposite behaviors emerged. The detector showed a recovery when illuminated after the bias-induced polarization had completely progressed. Conversely, when the detector was illuminated before the emergence of bias-induced polarization, the degradation of the spectral properties was accelerated. Interpretation of these effects and discussion on the energy level of deep acceptors are presented.

  4. International Conference on Narrow Gap Semiconductors Held in Southampton, England on 19-23 July 1992. Abstracts Booklet

    Science.gov (United States)

    1992-07-01

    University, Liniz. Narrow gap semiconductors offer the possibility to investigate in detail the role of conduction electrons in spin relaxation processes. In...crucial role on device performance. Hg1 ,-Zn.Te (N2T) is considered an alternative material to Hg1 -. Cd.Te (NCT) for infrared detectors. To the best of our... iaSb -AlSb-InAs-AlSh-GaSb), focusing on the effects of a magnetic fiheld parallel to the tunneling current, that is, perpendicular to the materials

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

    International Nuclear Information System (INIS)

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

    2005-01-01

    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

  6. Room Temperature Hard Radiation Detectors Based on Solid State Compound Semiconductors: An Overview

    Science.gov (United States)

    Mirzaei, Ali; Huh, Jeung-Soo; Kim, Sang Sub; Kim, Hyoun Woo

    2018-05-01

    Si and Ge single crystals are the most common semiconductor radiation detectors. However, they need to work at cryogenic temperatures to decrease their noise levels. In contrast, compound semiconductors can be operated at room temperature due to their ability to grow compound materials with tunable densities, band gaps and atomic numbers. Highly efficient room temperature hard radiation detectors can be utilized in biomedical diagnostics, nuclear safety and homeland security applications. In this review, we discuss room temperature compound semiconductors. Since the field of radiation detection is broad and a discussion of all compound materials for radiation sensing is impossible, we discuss the most important materials for the detection of hard radiation with a focus on binary heavy metal semiconductors and ternary and quaternary chalcogenide compounds.

  7. Room Temperature Hard Radiation Detectors Based on Solid State Compound Semiconductors: An Overview

    Science.gov (United States)

    Mirzaei, Ali; Huh, Jeung-Soo; Kim, Sang Sub; Kim, Hyoun Woo

    2018-03-01

    Si and Ge single crystals are the most common semiconductor radiation detectors. However, they need to work at cryogenic temperatures to decrease their noise levels. In contrast, compound semiconductors can be operated at room temperature due to their ability to grow compound materials with tunable densities, band gaps and atomic numbers. Highly efficient room temperature hard radiation detectors can be utilized in biomedical diagnostics, nuclear safety and homeland security applications. In this review, we discuss room temperature compound semiconductors. Since the field of radiation detection is broad and a discussion of all compound materials for radiation sensing is impossible, we discuss the most important materials for the detection of hard radiation with a focus on binary heavy metal semiconductors and ternary and quaternary chalcogenide compounds.

  8. Energy response of neutron area monitor with silicon semiconductor detector

    International Nuclear Information System (INIS)

    Kitaguchi, Hiroshi; Izumi, Sigeru; Kobayashi, Kaoru; Kaihara, Akihisa; Nakamura, Takashi.

    1993-01-01

    A prototype neutron area monitor with a silicon semiconductor detector has been developed which has the energy response of 1 cm dose equivalent recommended by the ICRP-26. Boron and proton radiators are coated on the surface of the silicon semiconductor detector. The detector is set at the center of a cylindrical polyethylene moderator. This moderator is covered by a porous cadmium board which serves as the thermal neutron absorber. Neutrons are detected as α-particles generated by the nuclear reaction 10 B(n,α) 7 Li and as recoil protons generated by the interaction of fast neutrons with hydrogen. The neutron energy response of the monitor was measured using thermal neutrons and monoenergetic fast neutrons generated by an accelerator. The response was consistent with the 1 cm dose equivalent response required for the monitor within ±34% in the range of 0.025 - 15 Mev. (author)

  9. Cryostat for an well logging probe using a semiconductor detector

    International Nuclear Information System (INIS)

    Tapphorn, R.M.

    1978-01-01

    This invention proposes to construct an well logging tool of the type comprising a semiconductor radiation detector devoid of the defects usually observed. This aim is attained by means of a cryostat to cool a semiconductor radiation detector in a restricted space where the temperature is high. It includes a long box dimensioned to pass through a bore hole, a cryogenic chamber housed in the box, a vacuum chamber thermally insulating the cryogenic chamber and placed around it, a semiconductor radiation detector housed in the vacuum chamber in thermal contact with the cryogenic chamber and an active vacuum pump fitted in the box and connected to the vacuum chamber to maintain a vacuum in it. In an improved version, the vacuum pump is fitted outside the cryostat so that it operates independently of the temperature conditions in the cryostat. If the pump needs to be cooled to reduce the gas discharge, it can be fitted inside the cryostat and connected to the cryogenic chamber or a second cryostat can also be provided to cool the pump. The vacuum pump is designed to maintain the vacuum in the thermal insulation vacuum chamber at a desired figure, preferably 10 -4 Torr or under, in order to preserve the integrity of the thermal insulation layer around the cryogenic chamber and thereby extending the efficient operating period of the detector. The cryogenic material used is preferably of fusion resistant type such as Freon 22 [fr

  10. Improved spectrometric characteristics of thallium bromide nuclear radiation detectors

    CERN Document Server

    Hitomi, K; Shoji, T; Suehiro, T; Hiratate, Y

    1999-01-01

    Thallium bromide (TlBr) is a compound semiconductor with a high atomic number and wide band gap. In this study, nuclear radiation detectors have been fabricated from the TlBr crystals. The TlBr crystals were grown by the horizontal travelling molten zone (TMZ) method using the materials purified by many pass zone refining. The crystals were characterized by measuring the resistivity, the mobility-lifetime (mu tau) product and the energy required to create an electron-hole pair (the epsilon value). Improved energy resolution has been obtained by the TlBr radiation detectors. At room temperature the full-width at half-maximum (FWHM) for the 59.5, 122 and 662 keV gamma-ray photo peak obtained from the detectors were 3.3, 8.8 and 29.5 keV, respectively. By comparing the saturated peak position of the TlBr detector with that of the CdTe detector, the epsilon value has been estimated to be about 5.85 eV for the TlBr crystal.

  11. Applicability of a portable CdTe and NaI (Tl) spectrometer for activity measure

    International Nuclear Information System (INIS)

    Fernandes, Jaquiel Salvi

    2005-02-01

    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 241 Am, 133 Ba, 152 Eu, 3 sources of 137 Cs and soil samples contaminated with 137 Cs. It was performed a factorial planning 2 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 μS 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 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 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 7 Be content the MDA found was 2867 Bq.kg -1 at 4.15 cm. For the NaI (Tl) detector, analyzing the line of 661.65 keV, the 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 137 Cs MDA was 71 Bq.kg -1 . For the soil sample 7 Be content, at 2.8 cm of the Nal (Tl) detector, the obtained MDA was 91 Bq.kg -1 . Due to the minimum detectable activities found for the two detectors, we concluded that the employed in situ gamma ray spectrometer system allows the quantification of 137 Cs and 7 Be

  12. Design considerations for CdTe Nanotetrapods as electronic devices. krogstrup@fys.ku.dk.

    Science.gov (United States)

    Teich-McGoldrick, S L; Bellanger, M; Caussanel, M; Tsetseris, L; Pantelides, S T; Glotzer, S C; Schrimpf, R D

    2009-11-01

    We investigate the feasibility of using CdTe nanotetrapods as circuit elements using models and simulation at multiple scales. Technology computer-aided design tools are used to simulate the electrical behavior for both metal-semiconductor field-effect transistors and junction field-effect transistors. Our results show that by varying the doping concentrations and material composition, CdTe nanotetrapods have the potential to be useful circuit elements. Monte Carlo simulations provide insight into how control over interparticle and particle-substrate interactions can lead to the directed assembly of ordered arrays of electrically gated nanotetrapods.

  13. 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.

  14. Novel Approach to Front Contact Passivation for CdTe Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Kephart, Jason

    2018-02-18

    The goal of this project was to study the use of sputter-deposited oxide materials for interface passivation of CdTe-based photovoltaics. Several candidate materials were chosen based on their promise in passivating the CdTe and CdSeTe semiconductor interface, chemical and thermal stability to device processing, and ability to be deposited by sputter deposition.

  15. Development of (Cd,Zn)Te X-ray and gamma ray radiation detectors for medical and security applications

    International Nuclear Information System (INIS)

    Franc, J.; Hoeschl, P.; Belas, E.; Grill, V.; Fauler, A.; Dambacher, M.; Procz, S.

    2011-01-01

    Full text: There is a growing need for large area X-and Gamma radiation detectors for penetrating radiations in various fields of application e.g. astronomy, detectors for nuclear medicine, biosensor materials, security, non-proliferation of hazardous materials, and environmental applications etc. Direct X-rays conversion into electric charges in a semiconductor is envisaged with better spectroscopic characteristics to improve contrast and quantitative measurements compared to indirect detection using scintillators. The family of II-VI semiconductor materials combine a range of excellent properties such as their high sensitivity due to the high mobility-lifetime products, their high energy resolution as a consequence of the electron-hole pair formation energy, their reasonable maturity in terms of microelectronic technologies required for commercial detector fabrication, wide range of stopping power and band-gaps available. In particular, CdTe and Cd x Zn 1-x Te (CZT) with Zn=0.1 offer a favorable combination of physical and chemical properties that makes it attractive as a room temperature X-ray detector material of choice for many applications involving photon energies up to several hundreds of keV. From the scientific experience accumulated in the past years, the detector properties are strongly dependent on a series of parameters which must be strictly controlled during crystal growth, such as the homogeneity, stoichiometry and the related intrinsic defects which appear during the material growth, a high mobility-lifetime for electron and holes is mandatory etc. Production of detector-grade CdTe and CdZnTe on industrial scale is still a challenge and optimal growth methods and growth conditions have been under intensive investigation. Progress in crystal growth and characterization achieved in a project of Institute partnership between Charles University in Prague and University of Freiburg, Germany which was sponsored by Alexander von Humboldt Foundation, will

  16. Evaluation of scintillators and semiconductor detectors to image three-photon positron annihilation for positron emission tomography

    International Nuclear Information System (INIS)

    Abuelhia, E.; Spyrou, N.M.; Kacperski, K.; College University, Middlesex Hospital, London

    2008-01-01

    Positron emission tomography (PET) is rapidly becoming the main nuclear imaging modality of the present century. The future of PET instrumentation relies on semiconductor detectors because of their excellent characteristics. Three-photon positron annihilation has been recently investigated as a novel imaging modality, which demands the crucial high energy resolution of semiconductor detector. In this work the evaluation of the NaI(Tl) scintillator and HPGe and CdZTe semiconductor detectors, to construct a simple three-photon positron annihilation scanner has been explored. The effect of detector and scanner size on spatial resolution (FWHM) is discussed. The characteristics: energy resolution versus count rate and point-spread function of the three-photon positron annihilation image profile from triple coincidence measurements were investigated. (author)

  17. Proposal for a semiconductor high resolution tracking detector

    International Nuclear Information System (INIS)

    Rehak, P.

    1983-01-01

    A 'new' concept for detection and tracking of charged particles in high energy physics experiments is proposed. It combines a well known high purity semiconductor diode detector (HPSDD) with a heterojunction structure (HJ) and a negative electron affinity (NEA) surface. The detector should be capable of providing a two dimensional view (few cm 2 ) of multi-track events with the following properties: a) position resolution down to a few μm (10 8 position elements); b) high density of information (10 2 -10 3 dots per mm of minimum ionizing track); c) high rate capabilities (few MHz); d) live operation with options to be triggered and/or the information from the detector can be used as an input for the decision to record an event. (orig.)

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

    Science.gov (United States)

    McGregor, Douglas S.; Shultis, John K.; Rice, Blake B.; McNeil, Walter J.; Solomon, Clell J.; Patterson, Eric L.; Bellinger, Steven L.

    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.

  19. 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...

  20. A spectrometer filter for semiconductor and scintillation detectors

    International Nuclear Information System (INIS)

    Andronov, O.I.; Brovchenko, V.G.; Evdokimov, S.T.

    1995-01-01

    The paper describes an integrating low-pass filter which takes signals from a delay line. The filter changes triangular pulses into rectangular ones. The energy resolution of a semiconductor detector whose signal is processed by the filter is 15-20% better than using a common RC-filter. The integrator stores a charge due to the scintillation pulse during the integration time without loss. The energy and time resolution of the device with the spectrometer filter is better than with an RC-filter. The energy resolution of a bismuth-germanate detector in recording radiation from 137 Cs is 9.75%

  1. 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...

  2. Studying nanotoxic effects of CdTe quantum dots in Trypanosoma cruzi

    Directory of Open Access Journals (Sweden)

    Cecilia Stahl Vieira

    2011-03-01

    Full Text Available Semiconductor nanoparticles, such as quantum dots (QDs, were used to carry out experiments in vivo and ex vivo with Trypanosoma cruzi. However, questions have been raised regarding the nanotoxicity of QDs in living cells, microorganisms, tissues and whole animals. The objective of this paper was to conduct a QD nanotoxicity study on living T. cruzi protozoa using analytical methods. This was accomplished using in vitro experiments to test the interference of the QDs on parasite development, morphology and viability. Our results show that after 72 h, a 200 μM cadmium telluride (CdTe QD solution induced important morphological alterations in T. cruzi, such as DNA damage, plasma membrane blebbing and mitochondrial swelling. Flow cytometry assays showed no damage to the plasma membrane when incubated with 200 μM CdTe QDs for up to 72 h (propidium iodide cells, giving no evidence of classical necrosis. Parasites incubated with 2 μM CdTe QDs still proliferated after seven days. In summary, a low concentration of CdTe QDs (2 μM is optimal for bioimaging, whereas a high concentration (200 μM CdTe could be toxic to cells. Taken together, our data indicate that 2 μM QD can be used for the successful long-term study of the parasite-vector interaction in real time.

  3. Current problems in semiconductor detectors for high energy physics after particle irradiations

    International Nuclear Information System (INIS)

    Lazanu, Ionel

    2002-01-01

    The use of semiconductor materials as detectors in high radiation environments, as expected in future high energy accelerators or in space missions, poses severe problems in long-time operations, due to changes in the properties of the material, and consequently in the performances of detectors. This talk presents the major theoretical areas of current problems, reviews the works in this field and the stage of their understanding, including author's contributions The mechanisms of interaction of the projectile with the semiconductor, the production of primary defects, the physical quantities and the equations able to characterise and describe the radiation effects, and the equations of kinetics of defects are considered. Correlation between microscopic damage and detector performances and the possible ways to optimise the radiation hardness of materials are discussed. (author)

  4. Diodes based on semi-insulating CdTe crystals with Mo/MoO{sub x} contacts for X- and γ-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Maslyanchuk, O.; Kulchynsky, V.; Solovan, M. [Chernivtsi National University, Chernivtsi (Ukraine); Gnatyuk, V. [Institute of Semiconductor Physics, NAS of Ukraine, Kyiv (Ukraine); Potiriadis, C. [Greek Atomic Energy Commission, Attiki (Greece); Kaissas, I. [Greek Atomic Energy Commission, Attiki (Greece); Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki (Greece); Brus, V. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany)

    2017-03-15

    This paper reports on the possible applications of molybdenum oxide (Mo/MoO{sub x}) contacts in combination with semi-insulating CdTe crystals. The electrical contacts to p-type Cl-doped CdTe crystals were formed by the deposition of molybdenum oxide and pure molybdenum thin films by the DC reactive magnetron sputtering. Electrical properties of the prepared Mo-MoO{sub x}/p-CdTe/MoO{sub x}-Mo surface-barrier structures were investigated at different temperatures. It is shown that the rapid growth of the reverse current with increasing bias voltage higher than 10 V is caused by the space-charge limited currents. Spectrometric properties of the Mo-MoO{sub x}/p-CdTe/MoO{sub x}-Mo structures have been also analyzed. It is revealed that the developed heterojunction has shown promising characteristics for its practical application in X- and γ-ray radiation detector fabrication. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Prototype of the stacked CdZnTe semiconductor detector for 16N measurement

    International Nuclear Information System (INIS)

    Nishizawa, Hiroshi; Inujima, Hiroshi; Fujiwara, Hirotsugu; Nakamura, Hiroaki

    2001-01-01

    Prototype of the Stacked CdZnTe Semiconductor Detector for Measurement The prototype model of the stacked CdZnTe semiconductor detector, which is able to measure the 6.13 MeV γ-ray from 16 N, was fabricated. The prototype's response calculation was carried out by Monte-Carlo method. The result of the response calculation agreed with the experiment data of check sources of 137 Cs and 60 Co, and 16 N which was measured at vicinity of the primary cooling water pipe of the nuclear reactor. The source spectra were unfolded with detector's response function obtained by simulation, and it is indicated that the incident γ-ray energy and its intensity ratio was identified and that the energy of 6 MeV γ-ray could be measured by the prototype of the stacked detector. (author)

  6. 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.

  7. Green synthesis of water soluble semiconductor nanocrystals and their applications

    Science.gov (United States)

    Wang, Ying

    II-VI semiconductor nanomaterials, e.g. CdSe and CdTe, have attracted great attention over the past decades due to their fascinating optical and electrical properties. The research presented here focuses on aqueous semiconductor nanomaterials. The work can be generally divided into three parts: synthesis, property study and application. The synthetic work is devoted to develop new methods to prepare shape- and structure-controlled II-VI semiconductor nanocrystals including nanoparticles and nanowires. CdSe and CdSe CdS semiconductor nanocrystals have been synthesized using sodium citrate as a stabilizer. Upon prolonged illumination with visible light, photoluminescence quantum yield of those quantum dots can be enhanced up to 5000%. The primary reason for luminescence enhancement is considered to be the removing of specific surface states (photocorrosion) and the smoothing of the CdSe core surface (photoannealing). CdTe nanowires are prepared through self-organization of stabilizer-depleted CdTe nanoparticles. The dipolar-dipolar attraction is believed to be the driving force of nanowire formation. The rich surface chemistry of CdTe nanowire is reflected by the formation of silica shell with different morphologies when nanowires with different capping ligands are used. Te and Se nanowires are prepared by chemical decomposition of CdTe and CdSe nanoparticles in presence of an external chemical stimulus, EDTA. These results not only provide a new example of NP→NW transformation, but also lead to a better understanding of the molecular process occurring in the stabilizer-depleted nanoparticles. The applications of those semiconductor materials are primarily based on the construction of nano-structured ultrathin films with desirable functions by using layer-by-layer technique (LBL). We demonstrate that light-induced micro-scale multicolor luminescent patterns can be obtained on photoactivable CdSe/CdS nanoparticles thin films by combining the advantages of LBL as

  8. Applications of CdTe to nuclear medicine. Final report

    International Nuclear Information System (INIS)

    Entine, G.

    1985-01-01

    Uses of cadmium telluride (CdTe) nuclear detectors in medicine are briefly described. They include surgical probes and a system for measuring cerebral blood flow in the intensive care unit. Other uses include nuclear dentistry, x-ray exposure control, cardiology, diabetes, and the testing of new pharmaceuticals

  9. Photoluminescence measurement of polycrystalline CdTe made of high purity source material

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Hannes; Kraft, Christian; Heisler, Christoph; Geburt, Sebastian; Ronning, Carsten; Wesch, Werner [Institute of Solid State Physics, Friedrich Schiller Universitaet Jena, Helmholtzweg 3, 07743 Jena (Germany)

    2012-07-01

    CdTe is a common material for thin film solar cells. However, the mainly used CdTe source material is known to contain a high number of intrinsic defects and impurities. In this work we investigate the defect structure of high purity CdTe by means of Photoluminescence, which is a common method to detect the energy levels of defects in the band gap of semiconductors. We used a 633 nm HeNe-Laser at sample temperatures of 8 K. The examined samples were processed in a new vacuum system based on the PVD method. They yield significantly different spectra on as-grown samples compared to those measured on samples which are grown by the standard process, since the double peak at 1.55 eV was hardly detectable and the A-center correlated transition vanished. Instead a peak at 1.50 eV with pronounced phonon coupling was observed. The 1.50 eV peak is known from other measurements but has not been characterized so far. The intention of this work is to characterize this new feature and the influence of post deposition treatments of the CdTe layers on the PL spectra.

  10. Present status and future trends of semiconductor detectors

    International Nuclear Information System (INIS)

    Lakatos, Tamas

    1988-01-01

    Some examples of the applications of semiconductor radiation detectors are briefly outlined, in order to illustrate development trends. The major parameters including energy resolution and dead time are discussed, and their improvement by the application of temporally varying parameter filters is pointed out. Development trends point toward low-loss signal processing by using adaptive filtering, possibly digital filtering. (R.P.) 14 refs.; 3 figs

  11. Parallel of semi-empirical results simulated by MCNP of X-ray spectra with a semiconductor; Paralelo de resultado semi- empiricos simulados por MCNPX de espectros de raios-X com um semicondutor

    Energy Technology Data Exchange (ETDEWEB)

    Santos, L.R.; Vivolo, V.; Potiens, M.P.A., E-mail: dossantos.lucasrodrigues@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Navarro, M.V.T.; Santos, W.S. [Universidade Federal de Uberlandia (INFIS/UFU), MG (Brazil). Instituto de Fisica

    2016-07-01

    The aim of this study was to use the MCNPX radiation transport code to simulate X-ray spectra generated by a constant voltage system in a CdTe semiconductor detector. As part of the validation process, we obtained a series of experimental spectra. Comparatively, in all cases there is a good correlation between the two spectra. There were no statistically significant differences between the experimental results with the simulated. (author)

  12. MCNPX calculations for electron irradiated semiconductor detectors

    International Nuclear Information System (INIS)

    Sedlackova, K.; Necas, V.; Sagatova, A.; Zatko, B.

    2014-01-01

    This study aimed to treat some practical problems of (not only) semiconductor material irradiation by high energy electron beam using MCNPX simulation code. The relation between the absorbed dose and the fluency was found and the energy distribution of electron flux density was simulated on the top and back side of 270 μm thick GaAs, SiC and Si detectors. Furthermore, the dose depth profiles were calculated for GaAs, SiC and Si materials irradiated by 4 and 5 MeV electron beams. For the GaAs detector, a very good agreement with the experiment was shown. To match the absolute values of the absorbed dose with experimentally obtained values, the electron source emissivity has to be determined in relation to the electron beam setting parameters. (authors)

  13. Application of imitation for energy calibration of silicon semiconductor detectors

    CERN Document Server

    Aivazyan, G M; Mikaelyan, M A

    2003-01-01

    An effective method is described for energy calibration of semiconductor detectors (SCD) with different thickness. The method is based on imitating the charge on the input of the preamplifier deposited in SCD by known energy ionizing particles, the imitation being performed by a pulser with a partial with use of alpha-active sources. The results of laboratory studies of the described method are given with detectors of either large, 50-1000 mu m, or small, 18-20 mu m, thickness

  14. Application of imitation for energy calibration of silicon semiconductor detectors

    International Nuclear Information System (INIS)

    Aivazyan, G.M.; Badalyan, H.V.; Mikaelyan, M.A.

    2003-01-01

    An effective method is described for energy calibration of semiconductor detectors (SCD) with different thickness. The method is based on imitating the charge on the input of the preamplifier deposited in SCD by known energy ionizing particles, the imitation being performed by a pulser with a partial with use of α-active sources. The results of laboratory studies of the described method are given with detectors of either large, 50-1000μm, or small, 18-20 μm, thickness

  15. Caliste 64, a new CdTe micro-camera for hard X-ray spectro-imaging

    Science.gov (United States)

    Meuris, A.; Limousin, O.; Lugiez, F.; Gevin, O.; Blondel, C.; Pinsard, F.; Vassal, M. C.; Soufflet, F.; Le Mer, I.

    2009-10-01

    In the frame of the Simbol-X mission of hard X-ray astrophysics, a prototype of micro-camera with 64 pixels called Caliste 64 has been designed and several samples have been tested. The device integrates ultra-low-noise IDeF-X V1.1 ASICs from CEA and a 1 cm 2 Al Schottky CdTe detector from Acrorad because of its high uniformity and spectroscopic performance. The process of hybridization, mastered by the 3D Plus company, respects space applications standards. The camera is a spectro-imager with time-tagging capability. Each photon interacting in the semiconductor is tagged with a time, a position and an energy. Time resolution is better than 100 ns rms for energy deposits greater than 20 keV, taking into account electronic noise and technological dispersal of the front-end electronics. The spectrum summed across the 64 pixels results in an energy resolution of 664 eV fwhm at 13.94 keV and 842 eV fwhm at 59.54 keV, when the detector is cooled down to -10 °C and biased at -500 V.

  16. Caliste 64, a new CdTe micro-camera for hard X-ray spectro-imaging

    International Nuclear Information System (INIS)

    Meuris, A.; Limousin, O.; Lugiez, F.; Gevin, O.; Blondel, C.; Pinsard, F.; Vassal, M.C.; Soufflet, F.; Le Mer, I.

    2009-01-01

    In the frame of the Simbol-X mission of hard X-ray astrophysics, a prototype of micro-camera with 64 pixels called Caliste 64 has been designed and several samples have been tested. The device integrates ultra-low-noise IDeF-X V1.1 ASICs from CEA and a 1 cm 2 Al Schottky CdTe detector from Acrorad because of its high uniformity and spectroscopic performance. The process of hybridization, mastered by the 3D Plus company, respects space applications standards. The camera is a spectro-imager with time-tagging capability. Each photon interacting in the semiconductor is tagged with a time, a position and an energy. Time resolution is better than 100 ns rms for energy deposits greater than 20 keV, taking into account electronic noise and technological dispersal of the front-end electronics. The spectrum summed across the 64 pixels results in an energy resolution of 664 eV fwhm at 13.94 keV and 842 eV fwhm at 59.54 keV, when the detector is cooled down to -10 deg. C and biased at -500 V.

  17. Caliste 64, a new CdTe micro-camera for hard X-ray spectro-imaging

    Energy Technology Data Exchange (ETDEWEB)

    Meuris, A. [CEA, Irfu, Service d' Astrophysique, Bat. 709, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)], E-mail: aline.meuris@cea.fr; Limousin, O. [CEA, Irfu, Service d' Astrophysique, Bat. 709, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Lugiez, F.; Gevin, O. [CEA, Irfu, Service d' Electronique, de Detecteurs et d' Informatique, F-91191 Gif-sur-Yvette (France); Blondel, C.; Pinsard, F. [CEA, Irfu, Service d' Astrophysique, Bat. 709, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Vassal, M.C.; Soufflet, F. [3D Plus, 641 rue Helene Boucher, F-78532 Buc (France); Le Mer, I. [CEA, Irfu, Service d' Astrophysique, Bat. 709, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)

    2009-10-21

    In the frame of the Simbol-X mission of hard X-ray astrophysics, a prototype of micro-camera with 64 pixels called Caliste 64 has been designed and several samples have been tested. The device integrates ultra-low-noise IDeF-X V1.1 ASICs from CEA and a 1 cm{sup 2} Al Schottky CdTe detector from Acrorad because of its high uniformity and spectroscopic performance. The process of hybridization, mastered by the 3D Plus company, respects space applications standards. The camera is a spectro-imager with time-tagging capability. Each photon interacting in the semiconductor is tagged with a time, a position and an energy. Time resolution is better than 100 ns rms for energy deposits greater than 20 keV, taking into account electronic noise and technological dispersal of the front-end electronics. The spectrum summed across the 64 pixels results in an energy resolution of 664 eV fwhm at 13.94 keV and 842 eV fwhm at 59.54 keV, when the detector is cooled down to -10 deg. C and biased at -500 V.

  18. Nanosecond X-ray detector based on high resistivity ZnO single crystal semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaolong; He, Yongning, E-mail: yongning@mail.xjtu.edu.cn; Peng, Wenbo; Huang, Zhiyong; Qi, Xiaomeng; Pan, Zijian; Zhang, Wenting [School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Chen, Liang; Liu, Jinliang; Zhang, Zhongbing; Ouyang, Xiaoping [Radiation Detection Research Center, Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

    2016-04-25

    The pulse radiation detectors are sorely needed in the fields of nuclear reaction monitoring, material analysis, astronomy study, spacecraft navigation, and space communication. In this work, we demonstrate a nanosecond X-ray detector based on ZnO single crystal semiconductor, which emerges as a promising compound-semiconductor radiation detection material for its high radiation tolerance and advanced large-size bulk crystal growth technique. The resistivity of the ZnO single crystal is as high as 10{sup 13} Ω cm due to the compensation of the donor defects (V{sub O}) and acceptor defects (V{sub Zn} and O{sub i}) after high temperature annealing in oxygen. The photoconductive X-ray detector was fabricated using the high resistivity ZnO single crystal. The rise time and fall time of the detector to a 10 ps pulse electron beam are 0.8 ns and 3.3 ns, respectively, indicating great potential for ultrafast X-ray detection applications.

  19. Semiconductor tracker final integration and commissioning in the ATLAS detector

    International Nuclear Information System (INIS)

    Robichaud-Veronneau, Andree

    2008-01-01

    The SemiConductor Tracker (SCT) is part of the Inner Detector of the ATLAS experiment at the LHC. It is located between the Pixel detector and the Transition Radiation Tracker (TRT). During 2006 and 2007, the SCT was installed in its final position inside the ATLAS detector. The SCT barrel was lowered in 2006 and was tested for connectivity and noise. Common tests with the TRT to look for pick-up noise and grounding issues were also performed. The SCT end-caps were installed during summer 2007 and will undergo similar checks. The results from the various tests done before and after installation will be presented here.

  20. Gamma radiation detectors for safeguards applications

    International Nuclear Information System (INIS)

    Carchon, R.; Moeslinger, M.; Bourva, L.; Bass, C.; Zendel, M.

    2007-01-01

    The IAEA uses extensively a variety of gamma radiation detectors to verify nuclear material. These detectors are part of standardized spectrometry systems: germanium detectors for High-Resolution Gamma Spectrometry (HRGS); Cadmium Zinc Telluride (CZT) detectors for Room Temperature Gamma Spectrometry (RTGS); and NaI(Tl) detectors for Low Resolution Gamma Spectrometry (LRGS). HRGS with high-purity Germanium (HpGe) detectors cooled by liquid nitrogen is widely used in nuclear safeguards to verify the isotopic composition of plutonium or uranium in non-irradiated material. Alternative cooling systems have been evaluated and electrically cooled HpGe detectors show a potential added value, especially for unattended measurements. The spectrometric performance of CZT detectors, their robustness and simplicity are key to the successful verification of irradiated materials. Further development, such as limiting the charge trapping effects in CZT to provide improved sensitivity and energy resolution are discussed. NaI(Tl) detectors have many applications-specifically in hand-held radioisotope identification devices (RID) which are used to detect the presence of radioactive material where a lower resolution is sufficient, as they benefit from a generally higher sensitivity. The Agency is also continuously involved in the review and evaluation of new and emerging technologies in the field of radiation detection such as: Peltier-cooled CdTe detectors; semiconductor detectors operating at room temperature such as HgI 2 and GaAs; and, scintillator detectors using glass fibres or LaBr 3 . A final conclusion, proposing recommendations for future action, is made

  1. The use of GaSe semiconductor detectors for monitoring high energy muon beams

    CERN Document Server

    Mancini, A M; Murri, R; Quirini, A; Rizzo, A; Vasanelli, L

    1976-01-01

    GaSe semiconductor detectors have been successfully tested during one year for monitoring muon beams in the GeV range in the neutrino experiment at CERN. Their performances are comparable with those of commercial Si surface barrier detectors for this particular application. Crystal growth, detector fabrication and characterization are briefly described. Various advantages (cost, ruggedness, resistance to radiation damage, manufacturing simplicity, etc.) are discussed. (8 refs).

  2. Monte Carlo simulations of the particle transport in semiconductor detectors of fast neutrons

    International Nuclear Information System (INIS)

    Sedlačková, Katarína; Zaťko, Bohumír; Šagátová, Andrea; Nečas, Vladimír

    2013-01-01

    Several Monte Carlo all-particle transport codes are under active development around the world. In this paper we focused on the capabilities of the MCNPX code (Monte Carlo N-Particle eXtended) to follow the particle transport in semiconductor detector of fast neutrons. Semiconductor detector based on semi-insulating GaAs was the object of our investigation. As converter material capable to produce charged particles from the (n, p) interaction, a high-density polyethylene (HDPE) was employed. As the source of fast neutrons, the 239 Pu–Be neutron source was used in the model. The simulations were performed using the MCNPX code which makes possible to track not only neutrons but also recoiled protons at all interesting energies. Hence, the MCNPX code enables seamless particle transport and no other computer program is needed to process the particle transport. The determination of the optimal thickness of the conversion layer and the minimum thickness of the active region of semiconductor detector as well as the energy spectra simulation were the principal goals of the computer modeling. Theoretical detector responses showed that the best detection efficiency can be achieved for 500 μm thick HDPE converter layer. The minimum detector active region thickness has been estimated to be about 400 μm. -- Highlights: ► Application of the MCNPX code for fast neutron detector design is demonstrated. ► Simulations of the particle transport through conversion film of HDPE are presented. ► Simulations of the particle transport through detector active region are presented. ► The optimal thickness of the HDPE conversion film has been calculated. ► Detection efficiency of 0.135% was reached for 500 μm thick HDPE conversion film

  3. High-speed imaging at high x-ray energy: CdTe sensors coupled to charge-integrating pixel array detectors

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Julian; Tate, Mark W.; Shanks, Katherine S.; Philipp, Hugh T.; Weiss, Joel T.; Purohit, Prafull [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Chamberlain, Darol [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Gruner, Sol M., E-mail: smg26@cornell.edu [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States)

    2016-07-27

    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 describe the hybridization of CdTe sensors to 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/pixel/frame while framing at 1 kHz. Both detector chips consist of a 128×128 pixel array with (150 µm){sup 2} pixels.

  4. 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.

  5. 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...

  6. Schottky barrier CdTe(Cl) detectors for planetary missions

    International Nuclear Information System (INIS)

    Eisen, Yosef; Floyd, Samuel

    2002-01-01

    Schottky barrier cadmium telluride (CdTe) radiation detectors of dimensions 2mm x 2mm x 1mm and segmented monolithic 3cm x 3 cm x 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 x 2mm x 1mm CdTe operating at -30 degree sign 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 x 3cm x 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

  7. Advanced radiation detector development: Advanced semiconductor detector development: Development of a oom-temperature, gamma ray detector using gallium arsenide to develop an electrode detector

    International Nuclear Information System (INIS)

    Knoll, G.F.

    1995-11-01

    The advanced detector development project at the University of Michigan has completed the first full year of its current funding. Our general goals are the development of radiation detectors and spectrometers that are capable of portable room temperature operation. Over the past 12 months, we have worked primarily in the development of semiconductor spectrometers with open-quotes single carrierclose quotes response that offer the promise of room temperature operation and good energy resolution in gamma ray spectroscopy. We have also begun a small scale effort at investigating the properties of a small non-spectroscopic detector system with directional characteristics that will allow identification of the approximate direction in which gamma rays are incident. These activities have made use of the extensive clean room facilities at the University of Michigan for semiconductor device fabrication, and also the radiation measurement capabilities provided in our laboratory in the Phoenix Building on the North Campus. In addition to our laboratory based activities, Professor Knoll has also been a participant in several Department of Energy review activities held in the Forrestal Building and at the Germantown site. The most recent of these has been service on a DOE review panel chaired by Dr. Hap Lamonds that is reviewing the detector development programs supported through the Office of Arms Control and International Security

  8. 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.

  9. Segmented-spectrum detection mechanism for medical x-ray in CdTe

    Science.gov (United States)

    Shi, Zaifeng; Meng, Qingzhen; Cao, Qingjie; Yao, Suying

    2016-01-01

    This paper presents a segmented X-ray spectrum detection method based on a layered X-ray detector in Cadmium Telluride (CdTe) substrate. We describe the three-dimensional structure of proposed detector pixel and investigate the matched spectrum-resolving method. Polychromatic X-ray beam enter the CdTe substrate edge on and will be absorbed completely in different thickness varying with photon energy. Discrete potential wells are formed under external controlling voltage to collect the photo-electrons generated in different layers, and segmented X-ray spectrum can be deduced from the quantity of photo-electrons. In this work, we verify the feasibility of the segmented-spectrum detection mechanism by simulating the absorption of monochromatic X-ray in a CdTe substrate. Experiments in simulation show that the number of photo-electrons grow exponentially with the increase of incident thickness, and photons with different energy will be absorbed in various thickness. The charges generated in different layers are collected into adjacent potential wells, and collection efficiency is estimated to be about 87% for different incident intensity under the 40000V/cm electric field. Errors caused by charge sharing between neighboring layers are also analyzed, and it can be considered negligible by setting appropriate size of electrodes.

  10. Photon detector composed of metal and semiconductor nanoparticles

    International Nuclear Information System (INIS)

    Takahashi, Atsuo; Minoura, Norihiko; Karube, Isao

    2005-01-01

    Applying the function of the single electron transistor, a novel photon detector consisting of a self-assembled structure of metal and semiconductor nanoparticles and an organic insulating layer was developed. It showed coulomb blockade behavior under dark conditions and remarkable increase in current corresponding to light intensity under light irradiation. Ultraweak photon emission of about 600 counts per second in the ultraviolet region could be detected at room temperature by this photon counter

  11. Electrochemical Determination of Uric Acid at CdTe Quantum Dot Modified Glassy Carbon Electrodes.

    Science.gov (United States)

    Pan, Deng; Rong, Shengzhong; Zhang, Guangteng; Zhang, Yannan; Zhou, Qiang; Liu, Fenghai; Li, Miaojing; Chang, Dong; Pan, Hongzhi

    2015-01-01

    Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of uric acid (UA) at a CdTe quantum dot (QD) modified the glassy carbon electrode (GCE). CdTe QDs, as new semiconductor nanocrystals, can greatly improve the peak current of UA. The anodic peak current of UA was linear with its concentration between 1.0×10(-6) and 4.0×10(-4) M in 0.1 M pH 5.0 phosphate buffer solution. The LOD for UA at the CdTe electrode (1.0×10(-7) M) was superior to that of the GCE. In addition, we also determined the effects of scan rate, pH, and interferences of UA for the voltammetric behavior and detection. The results indicated that modified electrode possessed excellent reproducibility and stability. Finally, a new and efficient electrochemical sensor for detecting UA was developed.

  12. Size dependence of upconversion photoluminescence in MPA capped CdTe quantum dots: Existence of upconversion bright point

    Energy Technology Data Exchange (ETDEWEB)

    Ananthakumar, S. [Crystal Growth Centre, Anna University, Chennai 600025 (India); Jayabalan, J., E-mail: jjaya@rrcat.gov.in [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Singh, Asha; Khan, Salahuddin [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Babu, S. Moorthy [Crystal Growth Centre, Anna University, Chennai 600025 (India); Chari, Rama [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2016-01-15

    The photoluminescence (PL) from semiconductor quantum dots can show a “PL bright point”, that is the PL from as prepared quantum dots is maximum at a particular size. In this work we show that, for CdTe quantum dots, upconversion photoluminescence (UCPL) originating from nonlinear absorption shows a similar “UCPL bright point”. The PL and UCPL bright points occur at nearly the same size. The existence of a UCPL bright point has important implications for upconversion microscopy applications. - Highlights: • The size dependence of the upconversion photoluminescence (UCPL) spectrum of CdTe quantum dots has been reported. • We show that the UCPL from the CdTe quantum dots is highest at a particular size. • Thus the occurrence of a 'UCPL bright point' in CdTe quantum dots has been demonstrated. • It has been shown that the UCPL bright point occurs at nearly the same size as a normal bright point.

  13. Size dependence of upconversion photoluminescence in MPA capped CdTe quantum dots: Existence of upconversion bright point

    International Nuclear Information System (INIS)

    Ananthakumar, S.; Jayabalan, J.; Singh, Asha; Khan, Salahuddin; Babu, S. Moorthy; Chari, Rama

    2016-01-01

    The photoluminescence (PL) from semiconductor quantum dots can show a “PL bright point”, that is the PL from as prepared quantum dots is maximum at a particular size. In this work we show that, for CdTe quantum dots, upconversion photoluminescence (UCPL) originating from nonlinear absorption shows a similar “UCPL bright point”. The PL and UCPL bright points occur at nearly the same size. The existence of a UCPL bright point has important implications for upconversion microscopy applications. - Highlights: • The size dependence of the upconversion photoluminescence (UCPL) spectrum of CdTe quantum dots has been reported. • We show that the UCPL from the CdTe quantum dots is highest at a particular size. • Thus the occurrence of a "UCPL bright point" in CdTe quantum dots has been demonstrated. • It has been shown that the UCPL bright point occurs at nearly the same size as a normal bright point.

  14. Semiconductor devices as track detectors in high energy colliding beam experiments

    International Nuclear Information System (INIS)

    Ludlam, T.

    1980-01-01

    In considering the design of experiments for high energy colliding beam facilities one quickly sees the need for better detectors. The full exploitation of machines like ISABELLE will call for detector capabilities beyond what can be expected from refinements of the conventional approaches to particle detection in high energy physics experiments. Over the past year or so there has been a general realization that semiconductor device technology offers the possibility of position sensing detectors having resolution elements with dimensions of the order of 10 microns or smaller. Such a detector could offer enormous advantages in the design of experiments, and the purpose of this paper is to discuss some of the possibilities and some of the problems

  15. Semiconductor devices as track detectors in high energy colliding beam experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ludlam, T

    1980-01-01

    In considering the design of experiments for high energy colliding beam facilities one quickly sees the need for better detectors. The full exploitation of machines like ISABELLE will call for detector capabilities beyond what can be expected from refinements of the conventional approaches to particle detection in high energy physics experiments. Over the past year or so there has been a general realization that semiconductor device technology offers the possibility of position sensing detectors having resolution elements with dimensions of the order of 10 microns or smaller. Such a detector could offer enormous advantages in the design of experiments, and the purpose of this paper is to discuss some of the possibilities and some of the problems.

  16. Electrodeposition of CdTe thin film from acetate-based ionic liquid bath

    Science.gov (United States)

    Waldiya, Manmohansingh; Bhagat, Dharini; Mukhopadhyay, Indrajit

    2018-05-01

    CdTe being a direct band gap semiconductor, is mostly used in photovoltaics. Here we present, the synthesis of CdTe thin film on fluorine doped tin oxide (FTO) substrate potentiostatically using 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]) ionic liquid (IL) bath at 90 °C. Major advantages of using electrodeposition involves process simplicity, large scalability & economic viability. Some of the benefits offered by IL electrolytic bath are low vapour pressure, wide electrochemical window, and good ionic mobility. Cd(CH3COO)2 (anhydrous) and TeO2 were used as the source precursors. The IL electrolytic bath temperature was kept at 90 °C for deposition, owing to the limited solubility of TeO2 in [Bmim][Ac] IL at room temperature. Cathodic electrodeposition was carried out using a three electrode cell setup at a constant potential of -1.20 V vs. platinum (Pt) wire. The CdTe/FTO thin film were annealed in argon (Ar) atmosphere. Optical study of nanostructured CdTe film were done using UV-Vis-IR and Raman spectroscopy. Raman analysis confirms the formation of CdTe having surface optics (SO) mode at 160.6 cm-1 and transverse optics (TO) mode at 140.5 cm-1. Elemental Te peaks at 123, 140.5 and 268 cm-1 were also observed. The optical band gap of Ar annealed CdTe thin film were found to be 1.47 eV (absorbance band edge ˜ 846 nm). The optimization of deposition parameters using acetate-based IL electrolytic bath to get nearly stoichiometric CdTe thin film is currently being explored.

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

    International Nuclear Information System (INIS)

    Odaka, Hirokazu; Ichinohe, Yuto; Takeda, Shin'ichiro; Fukuyama, Taro; Hagino, Koichi; Saito, Shinya; Sato, Tamotsu; Sato, Goro; Watanabe, Shin; Kokubun, Motohide; Takahashi, Tadayuki; Yamaguchi, Mitsutaka

    2012-01-01

    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-μm-thick Si-DSD and four layers of 750-μm-thick CdTe-DSDs all of which have common electrode configuration segmented into 128 strips on each side with pitches of 250μm. 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° at 356 keV and 3.5° 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Araghi, Houshang, E-mail: araghi@aut.ac.ir [Department of Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Zabihi, Zabiholah [Department of Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Nayebi, Payman [Department of Physics, College of Technical and Engineering, Saveh Branch, Islamic Azad University, Saveh (Iran, Islamic Republic of); Ehsani, Mohammad Mahdi [Department of Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2016-10-15

    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.

  19. 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.

  20. Application of a radiation detector in the interdisciplinary study. 1. Portable fluorescent X-ray analysis using the Si-PIN photodiode

    International Nuclear Information System (INIS)

    Ito, Yutaka

    2000-01-01

    As a semiconductor used for X-ray detector has excellent resolution, it must be cooled by liquid nitrogen at its use, which is a limitation on its actual use and applications. Then, a compound detector with wider bandwidth such as CdTe and HgI 2 has conventionally been used to attempt to use the detector at room temperature. Here was adopted an Si-PIN photodiode for a representative small type semiconductor detector unnecessary for liquid nitrogen, to introduce small and portable fluorescent X-ray analyzer for its application. As Si-PIN can work at room temperature, it has large leak current and insufficiently spread empty phase, so it is used by cooling due to Peltier element and so on. Then, here was used an X-ray detector, XR-100CR of AMPTEK Inc. composed of Si-PIN photodiode and a Pre-AMP. And, for a portable fluorescent X-ray analyzer, the Si-PIN photodiode detector of AMPTEK Inc., and a closely sealed small radiation source of 50 μ Ci 241 Am for excitation of X-ray in specimen were used. Its working principle consists of excitation of elements in a specimen with X- and gamma-ray from 241 Am, and detection of emitted fluorescent X-ray with Si-PIN photodiode. (G.K.)

  1. Digital approach to high-resolution pulse processing for semiconductor detectors

    International Nuclear Information System (INIS)

    Georgiev, A.; Buchner, A.; Gast, W.; Lieder, R.M.

    1992-01-01

    A new design philosophy for processing signals produced by high resolution, large volume semiconductor detectors is described. These detectors, to be used in the next generation of spectrometer arrays for nuclear research (i.e. EUROBALL, etc.), present a set of problems like resolution degradation due to charge trapping and ballistic defect effects, low resolution at a high count rate, poor long term stability, etc. To solve these problems, a new design approach has been developed, including reconstruction of the event charge, providing a pure triangular residual function, and suppressing low frequency noise. 5 refs., 4 figs

  2. Digital approach to high-resolution pulse processing for semiconductor detectors

    Energy Technology Data Exchange (ETDEWEB)

    Georgiev, A [Sofia Univ. (Bulgaria); Buchner, A [Forschungszentrum Rossendorf (Germany); Gast, W; Lieder, R M [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Kernphysik; Stein, J [Target System Electronic GmbH, Solingen, (Germany)

    1992-08-01

    A new design philosophy for processing signals produced by high resolution, large volume semiconductor detectors is described. These detectors, to be used in the next generation of spectrometer arrays for nuclear research (i.e. EUROBALL, etc.), present a set of problems like resolution degradation due to charge trapping and ballistic defect effects, low resolution at a high count rate, poor long term stability, etc. To solve these problems, a new design approach has been developed, including reconstruction of the event charge, providing a pure triangular residual function, and suppressing low frequency noise. 5 refs., 4 figs.

  3. 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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. A novel method for simultaneous observations of plasma ion and electron temperatures using a semiconductor-detector array

    International Nuclear Information System (INIS)

    Cho, T.; Numakura, T.; Kohagura, J.; Hirata, M.; Minami, R.; Watanabe, H.; Sasuga, T.; Nishizawa, Y.; Yoshida, M.; Nagashima, S.; Nakashima, Y.; Ogura, K.; Tamano, T.; Yatsu, K.; Miyoshi, S.

    2002-01-01

    A new method for a simultaneous observation of both plasma ion and electron temperatures is proposed using one semiconductor-detector array alone. This method will provide a new application of semiconductor-detector arrays for monitoring the key parameter set of nuclear-fusion triple product (i.e., ion temperatures, densities, and confinement time) as well as for clarifying physics mechanisms of energy transport between plasma ions and electrons under various plasma confining conditions. This method is developed on the basis of an alternative 'positive' use of a semiconductor 'dead layer'; that is, an SiO 2 layer is employed as a reliable ultra-thin energy analysis filter for low-energy charge-exchanged neutral particles from plasmas ranging in ion temperatures from 0.1 to several tens of kilo-electron-volts. Using recent fabrication techniques for the thin and uniform SiO 2 layers of the order of tens to hundreds of angstrom, our computer simulation and its experimental verification show the availability of such semiconductors for distinguishing neutral particles (for ion temperatures) from X-rays (for electron temperatures). These are simultaneously emitted from the plasmas into semiconductor detectors; however, we employ their quite different penetration lengths and the resultant different deposition depths and profiles in semiconductor materials. As a result, their output signals are distinguishable for these two different and fundamental species of plasmas

  5. Investigations on commercial semiconductor diodes as possible high dose rate radiation detectors

    International Nuclear Information System (INIS)

    Breitenhuber, L.; Kindl, P.; Obenaus, B.

    1992-12-01

    Investigations concerning the relevant properties of commercial semiconductor diodes such as their sensitivity and its dependence on accumulated dose, dose rate, energy, temperature and direction have been made in order to obtain their usefullness as radiation detectors. (authors)

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

    International Nuclear Information System (INIS)

    Krizaj, D.; Resnik, D.; Vrtacnik, D.; Amon, S.

    1998-01-01

    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

  7. Development of large area silicon semiconductor detectors for use in the current mode

    CERN Document Server

    Ouyang Xia Opin; Li Zhen Fu; Zhang Guo Guang; Zhang Qi; Zhang Xia; Song Xian Cai; Jia Huan Yi; Lei Jian Hua; Sun Yuan Cheng

    2002-01-01

    Large area silicon semiconductor detectors for use in the current mode, with their dimensions of phi 40, phi 50 and phi 60 mm, their depletion thickness of 200-300 mu m, have been developed. Their performance measurements have been made, which indicate that the developed detectors can satisfactorily meet the needs in expectation. Compared with the detectors commercially available on the market, authors' large PIN detectors can serve both as reliable and efficient high-resolution devices for nuclear counting experiments, as well as monitors of high-intensity radiation fields in the current mode under a bias of 100-1000 V, while the detectors commercially available are only for the counting use

  8. Metastability and reliability of CdTe solar cells

    Science.gov (United States)

    Guo, Da; Brinkman, Daniel; Shaik, Abdul R.; Ringhofer, Christian; Vasileska, Dragica

    2018-04-01

    Thin-film modules of all technologies often suffer from performance degradation over time. Some of the performance changes are reversible and some are not, which makes deployment, testing, and energy-yield prediction more challenging. Manufacturers devote significant empirical efforts to study these phenomena and to improve semiconductor device stability. Still, understanding the underlying reasons of these instabilities remains clouded due to the lack of ability to characterize materials at atomistic levels and the lack of interpretation from the most fundamental material science. The most commonly alleged causes of metastability in CdTe devices, such as ‘migration of Cu’, have been investigated rigorously over the past fifteen years. Still, the discussion often ended prematurely with stating observed correlations between stress conditions and changes in atomic profiles of impurities or CV doping concentration. Multiple hypotheses suggesting degradation of CdTe solar cell devices due to interaction and evolution of point defects and complexes were proposed, and none of them received strong theoretical or experimental confirmation. It should be noted that atomic impurity profiles in CdTe provide very little intelligence on active doping concentrations. The same elements could form different energy states, which could be either donors or acceptors, depending on their position in crystalline lattice. Defects interact with other extrinsic and intrinsic defects; for example, changing the state of an impurity from an interstitial donor to a substitutional acceptor often is accompanied by generation of a compensating intrinsic interstitial donor defect. Moreover, all defects, intrinsic and extrinsic, interact with the electrical potential and free carriers so that charged defects may drift in the electric field and the local electrical potential affects the formation energy of the point defects. Such complexity of interactions in CdTe makes understanding of temporal

  9. Three-dimensional minority carrier lifetime mapping of thin film semiconductors for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Hardin, Brian [PLANT PV, Inc., Belmont, CA (United States); Peters, Craig [PLANT PV, Inc., Belmont, CA (United States); Barnard, Edward [PLANT PV, Inc., Belmont, CA (United States)

    2015-09-30

    This project addresses the difficulty of accurately measuring charge carrier dynamics in novel semiconductor materials for thin film photovoltaic cells. We have developed a two- photon lifetime tomography technique to separate bulk minority carrier lifetime from surface recombination effects and effects of recombination at sub-surface defects. This technique also enables us to characterize how local defects such as grain boundaries– buried below the surface of a sample–affect carrier lifetimes in the active layer, dynamics that have been previously inaccessible. We have applied this newly developed technique to illuminate how CdCl2 treatment improves CdTe PV efficiency. From striking 3D lifetime tomography maps, a clear, sub- surface understanding emerges of the photophysical changes that occur in CdTe active medium following exposure to CdCl2, a standard step in the fabrication of high-efficiency CdTe-based solar cells. This work demonstrates a well-defined method to quantify grain-boundary, interface, and bulk recombination in CdTe and other optically-active polycrystalline semiconductor materials; information that can provide critical information to the development of next- generation photovoltaics and many other semiconductor technologies.

  10. Trends in the design of front-end systems for room temperature solid state detectors

    International Nuclear Information System (INIS)

    Manfredi, Pier F.; Re, Valerio

    2003-01-01

    The paper discusses the present trends in the design of low-noise front-end systems for room temperature semiconductor detectors. The technological advancement provided by submicron CMOS and BiCMOS processes is examined from several points of view. The noise performances are a fundamental issue in most detector applications and suitable attention is devoted to them for the purpose of judging whether or not the present processes supersede the solutions featuring a field-effect transistor as a front-end element. However, other considerations are also important in judging how well a monolithic technology suits the front-end design. Among them, the way a technology lends itself to the realization of additional functions, for instance, the charge reset in a charge-sensitive loop or the time-variant filters featuring the special weighting functions that may be requested in some applications of CdTe or CZT detectors

  11. 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

  12. CdTe ambulatory ventricular function monitor

    International Nuclear Information System (INIS)

    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

  13. 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.

  14. Detection of secondary electrons with pixelated hybrid semiconductor detectors

    International Nuclear Information System (INIS)

    Gebert, Ulrike Sonja

    2011-01-01

    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 -5 mbar and an acceleration voltage of 20 kV, the dark rate was about 800 Hz per mm 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 2 . To achieve this, a new photocathode was mounted in a shorter distance to the detector. The measurements where

  15. 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

  16. Palladium silicide - a new contact for semiconductor radiation detectors

    International Nuclear Information System (INIS)

    Totterdell, D.H.J.

    1981-11-01

    Silicide layers can be used as low resistance contacts in semiconductor devices. The formation of a metal rich palladium silicide Pd 2 Si is discussed. A palladium film 100A thick is deposited at 300 0 C and the resulting silicide layer used as an ohmic contact in an n + p silicon detector. This rugged contact has electrical characteristics comparable with existing evaporated gold contacts and enables the use of more reproducible bonding techniques. (author)

  17. Characterization of CdZnTe ambient temperature detectors

    International Nuclear Information System (INIS)

    Lavietes, A.

    1994-09-01

    A great deal of interest has been generated in the use of cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) detectors for ambient temperature detection of radionuclides. The addition of zinc to CdTe provides several benefits that enhance the materials operational characteristics at ambient temperature. Recent movement in the industry is to produce larger volume detectors using CdZnTe without much known about the effects of larger geometry on performance. The purpose of this study is to get an idea of the relationship of detector performance to both area and thickness variations

  18. Ion implantation of CdTe single crystals

    International Nuclear Information System (INIS)

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

    2017-01-01

    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 (10"1"7 1/cm"2). 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.

  19. Treatment verification and in vivo dosimetry for total body irradiation using thermoluminescent and semiconductor detectors

    International Nuclear Information System (INIS)

    Oliveira, F.F.; Amaral, L.L.; Costa, A.M.; Netto, T.G.

    2014-01-01

    The objective of this work is the characterization of thermoluminescent and semiconductor detectors and their applications in treatment verification and in vivo dosimetry for total body irradiation (TBI) technique. Dose measurements of TBI treatment simulation performed with thermoluminescent detectors inserted in the holes of a “Rando anthropomorphic phantom” showed agreement with the prescribed dose. For regions of the upper and lower chest where thermoluminescent detectors received higher doses it was recommended the use of compensating dose in clinic. The results of in vivo entrance dose measurements for three patients are presented. The maximum percentual deviation between the measurements and the prescribed dose was 3.6%, which is consistent with the action level recommended by the International Commission on Radiation Units and Measurements (ICRU), i.e., ±5%. The present work to test the applicability of a thermoluminescent dosimetric system and of a semiconductor dosimetric system for performing treatment verification and in vivo dose measurements in TBI techniques demonstrated the value of these methods and the applicability as a part of a quality assurance program in TBI treatments. - Highlights: • Characterization of a semiconductor dosimetric system. • Characterization of a thermoluminescent dosimetric system. • Application of the TLDs for treatment verification in total body irradiation treatments. • Application of semiconductor detectors for in vivo dosimetry in total body irradiation treatments. • Implementation of in vivo dosimetry as a part of a quality assurance program in radiotherapy

  20. Polarization phenomena in Al/p-CdTe/Pt X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Principato, F., E-mail: fabio.principato@unipa.it; Turturici, A.A.; Gallo, M.; Abbene, L.

    2013-12-01

    Over the last decades, CdTe detectors are widely used for the development of room temperature X-ray and gamma ray spectrometers. Typically, high resolution CdTe detectors are fabricated with blocking contacts (indium and aluminum) ensuring low leakage currents and high electric field for optimum charge collection. As well known, time instability under bias voltage (termed as polarization) is the major drawback of CdTe diode detectors. Polarization phenomena cause a progressive degradation of the spectroscopic performance with time, due to hole trapping and detrapping from deep acceptors levels. In this work, we studied the polarization phenomenon on new Al/p-CdTe/Pt detectors, manufactured by Acrorad (Japan), through electrical and spectroscopic approaches. In particular, we investigated on the time degradation of the spectroscopic response of the detectors at different temperatures, voltages and energies. Current transient measurements were also performed to better understand the properties of the deep acceptor levels and their correlation with the polarization effect.

  1. Fast optical recording media based on semiconductor nanostructures for image recording and processing

    International Nuclear Information System (INIS)

    Kasherininov, P. G.; Tomasov, A. A.

    2008-01-01

    Fast optical recording media based on semiconductor nanostructures (CdTe, GaAs) for image recording and processing with a speed to 10 6 cycle/s (which exceeds the speed of known recording media based on metal-insulator-semiconductor-(liquid crystal) (MIS-LC) structures by two to three orders of magnitude), a photosensitivity of 10 -2 V/cm 2 , and a spatial resolution of 5-10 (line pairs)/mm are developed. Operating principles of nanostructures as fast optical recording media and methods for reading images recorded in such media are described. Fast optical processors for recording images in incoherent light based on CdTe crystal nanostructures are implemented. The possibility of their application to fabricate image correlators is shown.

  2. Determining dose rate with a semiconductor detector - Monte Carlo calculations of the detector response

    Energy Technology Data Exchange (ETDEWEB)

    Nordenfors, C

    1999-02-01

    To determine dose rate in a gamma radiation field, based on measurements with a semiconductor detector, it is necessary to know how the detector effects the field. This work aims to describe this effect with Monte Carlo simulations and calculations, that is to identify the detector response function. This is done for a germanium gamma detector. The detector is normally used in the in-situ measurements that is carried out regularly at the department. After the response function is determined it is used to reconstruct a spectrum from an in-situ measurement, a so called unfolding. This is done to be able to calculate fluence rate and dose rate directly from a measured (and unfolded) spectrum. The Monte Carlo code used in this work is EGS4 developed mainly at Stanford Linear Accelerator Center. It is a widely used code package to simulate particle transport. The results of this work indicates that the method could be used as-is since the accuracy of this method compares to other methods already in use to measure dose rate. Bearing in mind that this method provides the nuclide specific dose it is useful, in radiation protection, since knowing what the relations between different nuclides are and how they change is very important when estimating the risks

  3. Position sensitive detector with semiconductor and image electron tube comprising such a detector

    International Nuclear Information System (INIS)

    Roziere, Guy.

    1977-01-01

    This invention concerns a position sensitive detector comprising a semiconducting substrate. It also concerns the electron tubes in which the detector may be incorporated in order to obtain an image formed at the tube input by an incident flux of particles or radiation. When a charged particle or group of such particles, electrons in particular, enter the space charge region of an inversely biased semiconductor diode, the energy supplied by these particles releases in the diode a certain number of electron-hole pairs which move in the field existing in the area towards the diode contacts. A corresponding current arises in the connections of this diode which constitutes the signal corresponding to the incident energy. Such a tube or chain of tubes is employed in nuclear medicine for observing parts of the human body, particularly by gamma radiation [fr

  4. Prospects of In/CdTe X- and γ-ray detectors with MoO Ohmic contacts

    Science.gov (United States)

    Maslyanchuk, Olena L.; Solovan, Mykhailo M.; Maistruk, Eduard V.; Brus, Viktor V.; Maryanchuk, Pavlo D.; Gnatyuk, Volodymyr A.; Aoki, Toru

    2018-01-01

    The present paper analyzes the charge transport mechanisms and spectrometric properties of In/CdTe/MoOx heterojunctions prepared by magnetron sputtering of indium and molybdenum oxide thin films onto semi-insulating p-type single-crystal CdTe semiconductor, produced by Acrorad Co. Ltd. Current-voltage characteristics of the detectors at different temperatures were investigated. The charge transport mechanisms in the heterostructures under investigation were determined: the generation-recombination in the space charge region (SCR) at relatively low voltages and the space charge limited currents at high voltages. The spectra of 137Cs and 241Am isotopes taken at different applied bias voltages are presented. It is shown that the In/CdTe/MoOx structures can be used as X/γ-ray detectors in the spectrometric mode.

  5. CDZNTE ROOM-TEMPERATURE SEMICONDUCTOR GAMMA-RAY DETECTOR FOR NATIONAL-SECURITY APPLICATIONS.

    Energy Technology Data Exchange (ETDEWEB)

    CAMARDA,G.S.; BOLOTNIKOV, A.E.; CUI, Y.; HOSSAIN, A.; KOHMAN, K.T.; JAMES, R.B.

    2007-05-04

    One important mission of the Department of Energy's National Nuclear Security Administration is to develop reliable gamma-ray detectors to meet the widespread needs of users for effective techniques to detect and identify special nuclear- and radioactive-materials. Accordingly, the Nonproliferation and National Security Department at Brookhaven National Laboratory was tasked to evaluate existing technology and to develop improved room-temperature detectors based on semiconductors, such as CdZnTe (CZT). Our research covers two important areas: Improving the quality of CZT material, and exploring new CZT-based gamma-ray detectors. In this paper, we report on our recent findings from the material characterization and tests of actual CZT devices fabricated in our laboratory and from materials/detectors supplied by different commercial vendors. In particular, we emphasize the critical role of secondary phases in the current CZT material and issues in fabricating the CZT detectors, both of which affect their performance.

  6. 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.

  7. On load resistor noise in preamplifiers for semiconductor detectors

    International Nuclear Information System (INIS)

    Baldin, S.A.; Bajramashvili, I.A.; Gubin, S.F.

    1975-01-01

    The main causes resulting in the deterioration of energy resolution in preamplifiers for semiconductor detectors (scd) with a resistor in the feedback circuit are discussed. A comparison of noise characteristics has been carried out of a number of high-resistance commercial and experimental resistors. The resistor noise dependence on the nature of drop of the resistor impedance active part in the region up to 100 Kc, as well as on the resistor spurious capacitance in shown

  8. Development of a cadmium telluride pixel detector for astrophysical applications

    Science.gov (United States)

    Miyasaka, Hiromasa; Harrison, Fiona A.; Cook, Walter R.; Mao, Peter H.; Rana, Vikram R.; Ishikawa, Shin-Nosuke; Ushio, Masayoshi; Aono, Hiroyuki; Watanabe, Shin; Sato, Goro; Kokubun, Motohide; Takahashi, Tadayuki

    2009-08-01

    We are developing imaging Cadmium Telluride (CdTe) pixel detectors optimized for astrophysical hard X-ray applications. Our hybrid detector consist of a CdTe crystal 1mm thick and 2cm × 2cm in area with segmented anode contacts directly bonded to a custom low-noise application specific integrated circuit (ASIC). The CdTe sensor, fabricated by ACRORAD (Okinawa, Japan), has Schottky blocking contacts on a 605 micron pitch in a 32 × 32 array, providing low leakage current and enabling readout of the anode side. The detector is bonded using epoxy-gold stud interconnects to a custom low noise, low power ASIC circuit developed by Caltech's Space Radiation Laboratory. We have achieved very good energy resolution over a wide energy range (0.62keV FWHM @ 60keV, 10.8keV FWHM @ 662keV). We observe polarization effects at room temperature, but they are suppressed if we operate the detector at or below 0°C degree. These detectors have potential application for future missions such as the International X-ray Observatory (IXO).

  9. Flux distribution by neutrons semi-conductors detectors during the startup of the EL4 reactor

    International Nuclear Information System (INIS)

    Fuster, S.; Tarabella, A.

    1967-01-01

    The Cea developed neutron semi-conductors detectors which allows a quasi-instantaneous monitoring of neutrons flux distribution, when placed in a reactor during the tests. These detectors have been experimented in the EL4 reactor. The experiment and the results are presented and compared with reference mappings. (A.L.B.)

  10. Observation of Hg-diffusion in CdTe using heavy ion (40MeV-O5+) backscattering

    International Nuclear Information System (INIS)

    Otake, H.; Takita, K.; Murakami, K.; Masuda, K.; Kudo, H.; Seki, S.

    1984-01-01

    Diffusion of Hg in the near-surface region of CdTe crystals was observed by means of 40MeV-O 5+ ion backscattering. CdTe crystals immersed in Hg were kept in furnace at 280 -- 340 0 C for 2 -- 240hours. The backscattering spectra of these crystals were measured. The concentration of the diffused Hg atoms in the surface reached to 4 x 10 20 cm -3 , and Hg distribution was observed up to 1.4 μm from surface. Temperature dependence of the diffusion coefficients was determined as D = 5 x 10 3 exp (-2.0 +- 0.3eV/kT) cm 2 /sec. Hg-diffusion was not observed in the case of CdTe kept in Hg with a small amount of Cd. These facts suggest that Hg diffusion is controlled by the diffusion of Cd-vacancy. A method of observing the Hg-atoms profile in the near-surface region of the semiconductor was established. (author)

  11. Spent-fuel characterization with small CZT detectors

    Energy Technology Data Exchange (ETDEWEB)

    Berndt, R. [European Commission, Joint Research Centre, Ispra, 21020 Ispra (Vatican City State, Holy See,) (Italy)]. E-mail: Reinhard.Berndt@jrc.it; Mortreau, P. [European Commission, Joint Research Centre, Ispra, 21020 Ispra (Va) (Italy)

    2006-08-01

    CdTe detectors may be utilised as miniature instruments for the measurement of gamma spectra in safeguards applications [R. Arlt, V. Gryshchuk, P. Sumah, Nucl. Instr. and Meth. A 428 (1999) 127]. This is applicable for measurements both to fresh fuel and irradiated nuclear fuel. The spectrum analysis, however, is more complicated than with Ge detectors. Some reasons are: the peaks are asymmetric, the peak/Compton ratio is low, peak parameters depend on the count rate and on the properties of individual detector crystals. We developed a spectrum-unfolding code for spectra obtained with CdTe detectors. The code makes use of a series of pattern spectra of the individual instrument. It is applied to fission-product spectra and allows the coarse characterisation of the spent fuel in safeguards inspections.

  12. Spent-fuel characterization with small CZT detectors

    International Nuclear Information System (INIS)

    Berndt, R.; Mortreau, P.

    2006-01-01

    CdTe detectors may be utilised as miniature instruments for the measurement of gamma spectra in safeguards applications [R. Arlt, V. Gryshchuk, P. Sumah, Nucl. Instr. and Meth. A 428 (1999) 127]. This is applicable for measurements both to fresh fuel and irradiated nuclear fuel. The spectrum analysis, however, is more complicated than with Ge detectors. Some reasons are: the peaks are asymmetric, the peak/Compton ratio is low, peak parameters depend on the count rate and on the properties of individual detector crystals. We developed a spectrum-unfolding code for spectra obtained with CdTe detectors. The code makes use of a series of pattern spectra of the individual instrument. It is applied to fission-product spectra and allows the coarse characterisation of the spent fuel in safeguards inspections

  13. Induced radioactivity in the forward shielding and semiconductor tracker of the ATLAS detector.

    Science.gov (United States)

    Bĕdajánek, I; Linhart, V; Stekl, I; Pospísil, S; Kolros, A; Kovalenko, V

    2005-01-01

    The radioactivity induced in the forward shielding, copper collimator and semiconductor tracker modules of the ATLAS detector has been studied. The ATLAS detector is a long-term experiment which, during operation, will require to have service and access to all of its parts and components. The radioactivity induced in the forward shielding was calculated by Monte Carlo methods based on GEANT3 software tool. The results show that the equivalent dose rates on the outer surface of the forward shielding are very low (at most 0.038 microSv h(-1)). On the other hand, the equivalent dose rates are significantly higher on the inner surface of the forward shielding (up to 661 microSv h(-1)) and, especially, at the copper collimator close to the beampipe (up to 60 mSv h(-1)). The radioactivity induced in the semiconductor tracker modules was studied experimentally. The module was activated by neutrons in a training nuclear reactor and the delayed gamma ray spectra were measured. From these measurements, the equivalent dose rate on the surface of the semiconductor tracker module was estimated to be LHC) operation and 10 d of cooling.

  14. Assessment of present and future large-scale semiconductor detector systems

    International Nuclear Information System (INIS)

    Spieler, H.G.; Haller, E.E.

    1984-11-01

    The performance of large-scale semiconductor detector systems is assessed with respect to their theoretical potential and to the practical limitations imposed by processing techniques, readout electronics and radiation damage. In addition to devices which detect reaction products directly, the analysis includes photodetectors for scintillator arrays. Beyond present technology we also examine currently evolving structures and techniques which show potential for producing practical devices in the foreseeable future

  15. Experimental investigation of energy resolution in a semiconductor detector (surface barrier and Si (Li) detector) in the detection of protons

    International Nuclear Information System (INIS)

    Nordborg, C.

    1974-05-01

    The action of electronic effects on the energy resolution of the detector is investigated. The results are applicable not only to protons but also to heavier charged particles. It should be possible to reach a resolution of about 6 to 7 keV for 10 MeV protons with electronic detectors. Magnetic spectrometers could achieve a resolution of 2 to 3 keV. It is convenient to use Peltier elements for cooling semiconductor spectrometers. (Auth.)

  16. Search for strongly interacting massive particles using semiconductor detectors on the ground

    International Nuclear Information System (INIS)

    Derbin, A.V.; Egorov, A.I.; Bakhlanov, S.V.; Muratova, V.N.

    1999-01-01

    Using signals from recoil nucleus in semiconductor detectors, search for strongly interacting massive particles, as a possible candidate for dark matter, is continued. Experimental installation and the experimental results are given. New limits on the possible masses and cross sections of strongly interacting massive particles are presented [ru

  17. A prototype small CdTe gamma camera for radioguided surgery and other imaging applications.

    Science.gov (United States)

    Tsuchimochi, Makoto; Sakahara, Harumi; Hayama, Kazuhide; Funaki, Minoru; Ohno, Ryoichi; Shirahata, Takashi; Orskaug, Terje; Maehlum, Gunnar; Yoshioka, Koki; Nygard, Einar

    2003-12-01

    Gamma probes have been used for sentinel lymph node biopsy in melanoma and breast cancer. However, these probes can provide only radioactivity counts and variable pitch audio output based on the intensity of the detected radioactivity. We have developed a small semiconductor gamma camera (SSGC) that allows visualisation of the size, shape and location of the target tissues. This study is designed to characterise the performance of the SSGC for radioguided surgery of metastatic lesions and for other imaging applications amenable to the smaller format of this prototype imaging system. The detector head had 32 cadmium telluride semiconductor arrays with a total of 1,024 pixels, and with application-specific integrated circuits (ASICs) and a tungsten collimator. The entire assembly was encased in a lead housing measuring 152 mmx166 mmx65 mm. The effective visual field was 44.8 mmx44.8 mm. The energy resolution and imaging aspects were tested. Two spherical 5-mm- and 15-mm-diameter technetium-99m radioactive sources that had activities of 0.15 MBq and 100 MBq, respectively, were used to simulate a sentinel lymph node and an injection site. The relative detectability of these foci by the new detector and a conventional scintillation camera was studied. The prototype was also examined in a variety of clinical applications. Energy resolution [full-width at half-maximum (FWHM)] for a single element at the centre of the field of view was 4.2% at 140 keV (99mTc), and the mean energy resolution of the CdTe detector arrays was approximately 7.8%. The spatial resolution, represented by FWHM, had a mean value of 1.56 +/- 0.05 mm. Simulated node foci could be visualised clearly by the SSGC using a 15-s acquisition time. In preliminary clinical tests, the SSGC successfully imaged diseases in a variety of tissues, including salivary and thyroid glands, temporomandibular joints and sentinel lymph nodes. The SSGC has significant potential for diagnosing diseases and facilitating

  18. A prototype small CdTe gamma camera for radioguided surgery and other imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchimochi, Makoto; Hayama, Kazuhide [Department of Oral and Maxillofacial Radiology, The Nippon Dental University School of Dentistry at Niigata, 1-8 Hamaura-cho, 951-8580, Niigata (Japan); Sakahara, Harumi [Department of Radiology, Hamamatsu University School of Medicine, Hamamatsu (Japan); Funaki, Minoru; Ohno, Ryoichi; Shirahata, Takashi [Acrorad Co. Ltd., Tokyo (Japan); Orskaug, Terje; Maehlum, Gunnar; Yoshioka, Koki; Nygard, Einar [Integrated Detector and Electronics A.S (IDE AS), Hovik (Norway)

    2003-12-01

    Gamma probes have been used for sentinel lymph node biopsy in melanoma and breast cancer. However, these probes can provide only radioactivity counts and variable pitch audio output based on the intensity of the detected radioactivity. We have developed a small semiconductor gamma camera (SSGC) that allows visualisation of the size, shape and location of the target tissues. This study is designed to characterise the performance of the SSGC for radioguided surgery of metastatic lesions and for other imaging applications amenable to the smaller format of this prototype imaging system. The detector head had 32 cadmium telluride semiconductor arrays with a total of 1,024 pixels, and with application-specific integrated circuits (ASICs) and a tungsten collimator. The entire assembly was encased in a lead housing measuring 152 mm x 166 mm x 65 mm. The effective visual field was 44.8 mm x 44.8 mm. The energy resolution and imaging aspects were tested. Two spherical 5-mm- and 15-mm-diameter technetium-99m radioactive sources that had activities of 0.15 MBq and 100 MBq, respectively, were used to simulate a sentinel lymph node and an injection site. The relative detectability of these foci by the new detector and a conventional scintillation camera was studied. The prototype was also examined in a variety of clinical applications. Energy resolution [full-width at half-maximum (FWHM)] for a single element at the centre of the field of view was 4.2% at 140 keV ({sup 99m}Tc), and the mean energy resolution of the CdTe detector arrays was approximately 7.8%. The spatial resolution, represented by FWHM, had a mean value of 1.56{+-}0.05 mm. Simulated node foci could be visualised clearly by the SSGC using a 15-s acquisition time. In preliminary clinical tests, the SSGC successfully imaged diseases in a variety of tissues, including salivary and thyroid glands, temporomandibular joints and sentinel lymph nodes. The SSGC has significant potential for diagnosing diseases and

  19. A prototype small CdTe gamma camera for radioguided surgery and other imaging applications

    International Nuclear Information System (INIS)

    Tsuchimochi, Makoto; Hayama, Kazuhide; Sakahara, Harumi; Funaki, Minoru; Ohno, Ryoichi; Shirahata, Takashi; Orskaug, Terje; Maehlum, Gunnar; Yoshioka, Koki; Nygard, Einar

    2003-01-01

    Gamma probes have been used for sentinel lymph node biopsy in melanoma and breast cancer. However, these probes can provide only radioactivity counts and variable pitch audio output based on the intensity of the detected radioactivity. We have developed a small semiconductor gamma camera (SSGC) that allows visualisation of the size, shape and location of the target tissues. This study is designed to characterise the performance of the SSGC for radioguided surgery of metastatic lesions and for other imaging applications amenable to the smaller format of this prototype imaging system. The detector head had 32 cadmium telluride semiconductor arrays with a total of 1,024 pixels, and with application-specific integrated circuits (ASICs) and a tungsten collimator. The entire assembly was encased in a lead housing measuring 152 mm x 166 mm x 65 mm. The effective visual field was 44.8 mm x 44.8 mm. The energy resolution and imaging aspects were tested. Two spherical 5-mm- and 15-mm-diameter technetium-99m radioactive sources that had activities of 0.15 MBq and 100 MBq, respectively, were used to simulate a sentinel lymph node and an injection site. The relative detectability of these foci by the new detector and a conventional scintillation camera was studied. The prototype was also examined in a variety of clinical applications. Energy resolution [full-width at half-maximum (FWHM)] for a single element at the centre of the field of view was 4.2% at 140 keV ( 99m Tc), and the mean energy resolution of the CdTe detector arrays was approximately 7.8%. The spatial resolution, represented by FWHM, had a mean value of 1.56±0.05 mm. Simulated node foci could be visualised clearly by the SSGC using a 15-s acquisition time. In preliminary clinical tests, the SSGC successfully imaged diseases in a variety of tissues, including salivary and thyroid glands, temporomandibular joints and sentinel lymph nodes. The SSGC has significant potential for diagnosing diseases and facilitating

  20. Formation of self assembled PbTe quantum dots in CdTe on Si(111)

    Science.gov (United States)

    Felder, F.; Fognini, A.; Rahim, M.; Fill, M.; Müller, E.; Zogg, H.

    2010-01-01

    We describe the growth and formation of self assembled PbTe quantum dots in a CdTe host on a silicon (111) substrate. Annealing yields different photoluminescence spectra depending on initial PbTe layer thickness, thickness of the CdTe cap layer and annealing temperature. Generally two distinct emission peaks at ˜0.3 eV and ˜0.45 eV are visible. Model calculations explaining their temperature dependence are performed. The dot size corresponds well with the estimated sizes from electron microscopy images. The quantum dots may be used as absorber within a mid-infrared detector.

  1. Semiconductor Pixel detectors and their applications in life sciences

    International Nuclear Information System (INIS)

    Jakubek, J

    2009-01-01

    Recent advances in semiconductor technology allow construction of highly efficient and low noise pixel detectors of ionizing radiation. Steadily improving quality of front end electronics enables fast digital signal processing in each pixel which offers recording of more complete information about each detected quantum (energy, time, number of particles). All these features improve an extend applicability of pixel technology in different fields. Some applications of this technology especially for imaging in life sciences will be shown (energy and phase sensitive X-ray radiography and tomography, radiography with heavy charged particles, neutron radiography, etc). On the other hand a number of obstacles can limit the detector performance if not handled. The pixel detector is in fact an array of individual detectors (pixels), each of them has its own efficiency, energy calibration and also noise. The common effort is to make all these parameters uniform for all pixels. However an ideal uniformity can be never reached. Moreover, it is often seen that the signal in one pixel can affect the neighbouring pixels due to various reasons (e.g. charge sharing). All such effects have to be taken into account during data processing to avoid false data interpretation. A brief view into the future of pixel detectors and their applications including also spectroscopy, tracking and dosimetry is given too. Special attention is paid to the problem of detector segmentation in context of the charge sharing effect.

  2. Structural and luminescent properties of Fe3+ doped PVA capped CdTe nanoparticles

    Directory of Open Access Journals (Sweden)

    Ravindranadh K.

    2017-07-01

    Full Text Available During recent decades, magnetic and semiconductor nanoparticles have attracted significant attention of scientists in various fields of engineering, physics, chemistry, biology and medicine. Fe3+ doped PVA capped CdTe nanoparticles were prepared by co-precipitation method and characterized by powder X-ray diffraction, SEM, TEM, FT-IR, optical, EPR and PL techniques to collect the information about the crystal structure, coordination/local site symmetry of doped Fe3+ ions in the host lattice and the luminescent properties of prepared sample. Powder XRD data revealed that the crystal structure belongs to a cubic system and its lattice cell parameters were evaluated. The average crystallite size was estimated to be 8 nm. The morphology of prepared samples was analyzed by using SEM and TEM investigations. Functional groups of the prepared sample were observed in FT-IR spectra. Optical absorption and EPR studies have shown that on doping, Fe3+ ions enter the host lattice in octahedral site symmetry. PL studies of Fe3+ doped PVA capped CdTe nanoparticles revealed UV and blue emission bands. CIE chromaticity coordinates were also calculated from the emission spectrum of Fe3+ doped PVA capped CdTe nanoparticles.

  3. Property of a CZT semiconductor detector for radionuclide identification

    International Nuclear Information System (INIS)

    Chun, Sung-Dae; Park, Se-Hwan; Ha, Jang Ho; Kang, Sang Mook; Lee, Dong Hoon; Kim, Yong Kyun; Cho, Yun Ho; Kim, Jong Kyung; Hong, Duk-Geun

    2008-01-01

    Compound semiconductors of high Z value material have been studied intensively for X-ray and γ-ray spectroscopy at room temperature. CdZnTe has wide band gap energy as 1.6 eV and can provide high quantum efficiency with reasonably good energy resolution at room temperature. This study is aimed at determining radionuclide analysis ability by measuring energy resolution of CZT detector which will be applied at nuclear material identification purpose. For experiment we used a CZT detector (5 x 5 x 5 mm 3 ) which is manufactured by eV Products. We have performed our measurement at varied temperatures similar to the outdoor environment for the investigation about temperature dependence of energy resolution and peak centroid fluctuation of CZT detector by using gas cooling and Peltier cooling methods. In order to test radionuclide identification we used various radionuclide samples; plutonium, europium and other standard sources. Pulse height spectra were obtained by standard electronics which consists of a preamplifier, a shaping amplifier, and a multi-channel analyzer. (author)

  4. Positron trapping in heavily irradiated semiconductors

    International Nuclear Information System (INIS)

    Moser, P.; Pautrat, J.L.; Corbel, C.; Hautojarvi, P.

    1985-01-01

    Vacancy processes are studied in several heavily irradiated semiconductors. Specimens are ZnTe, CdTe, CdTe (In), InP, InP (Cr), InP (Zn) and Ge. Irradiations are made at 20 K using a 3 MeV Van de Graaff electron accelerator. Doses are 4 x 10 18 e - /cm 2 . Lifetime measurements are made at 77 K at each step of an isochronal annealing (30 min 20 K). In each specimen, the results show a significant increase of the lifetime (+ 30 at + 50 ps) which anneals out in different steps restoring the initial lifetime. The steps are sharp (ΔT/T=0.3) with the exception of InP, InP(Cr), InP(Zn), (ΔT/T=0.9). Tentative interpretations are given

  5. 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.

  6. Use of semiconductor detectors for radioactive waste account and control

    CERN Document Server

    Davydov, L N; Zakharchenko, A A

    2002-01-01

    The possibilities and development status of the contemporary semiconductor detectors and detecting devices intended for radiation monitoring at nuclear industry enterprises, including Chernobyl Shelter and depositories of nuclear wastes are shown. Such devices,created in the last years, can be successfully used for measurements of the gamma-radiation dose rate as well as for the isotope composition evaluation of nuclear materials and wastes, both during the work cycles and in emergency situations.

  7. 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.

  8. 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.

  9. Current applications of semiconductor x-ray detectors in chemical analysis

    International Nuclear Information System (INIS)

    Whitehead, N.E.

    1975-07-01

    In the last few years, semiconductor detectors have been used as X-ray detectors with great success, and the routine rapid accumulation of X-ray spectra is now possible. This review surveys the historical development of the detectors, the utilisation, and relative merits of various means of exciting the X-radiation from the elements in the sample, and compares the technique with other methods claiming to offer the capability of simultaneous multi-element analysis. It is concluded that it is of average sensitivity, but offers some advantages from its non-destructive nature, and in some cases its ability to offer information about the spatial distribution of elements in a sample. Other types of analysis may also be possible simultaneously. Sample preparation techniques are reviewed, especially techniques of manufacturing thin samples. An appendix contains details of the very wide variety of samples which have been analysed. More than 350 references are included. (auth.)

  10. 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.

  11. CdTe layer structures for X-ray and gamma-ray detection directly grown on the Medipix readout-chip by MBE

    Science.gov (United States)

    Vogt, A.; Schütt, S.; Frei, K.; Fiederle, M.

    2017-11-01

    This work investigates the potential of CdTe semiconducting layers used for radiation detection directly deposited on the Medipix readout-chip by MBE. Due to the high Z-number of CdTe and the low electron-hole pair creation energy a thin layer suffices for satisfying photon absorption. The deposition takes place in a modified MBE system enabling growth rates up to 10 μm/h while the UHV conditions allow the required high purity for detector applications. CdTe sensor layers deposited on silicon substrates show resistivities up to 5.8 × 108 Ω cm and a preferred (1 1 1) orientation. However, the resistivity increases with higher growth temperature and the orientation gets more random. Additionally, the deposition of a back contact layer sequence in one process simplifies the complex production of an efficient contact on CdTe with aligned work functions. UPS measurements verify a decrease of the work function of 0.62 eV induced by Te doping of the CdTe.

  12. 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.

  13. 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.

  14. Development and characterization of semiconductor ion detectors for plasma diagnostics in the range over 0.3 keV

    Science.gov (United States)

    Cho, T.; Sakamoto, Y.; Hirata, M.; Kohagura, J.; Makino, K.; Kanke, S.; Takahashi, K.; Okamura, T.; Nakashima, Y.; Yatsu, K.; Tamano, T.; Miyoshi, S.

    1997-01-01

    For the purpose of plasma-ion-energy analyses in a wide-energy range from a few hundred eV to hundreds of keV, upgraded semiconductor detectors are newly fabricated and characterized using a test-ion-beam line from 0.3 to 12 keV. In particular, the detectable lowest-ion energy is drastically improved at least down to 0.3 keV; this energy is one to two orders-of-magnitude better than those for commercially available Si-surface-barrier diodes employed for previous plasma-ion diagnostics. A signal-to-noise ratio of two to three orders-of-magnitude better than that for usual metal-collector detectors is demonstrated for the compact-sized semiconductor along with the availability of the use under conditions of a good vacuum and a strong-magnetic field. Such characteristics are achieved due to the improving methods of the optimization of the thicknesses of a Si dead layer and a SiO2 layer, as well as the nitrogen-doping technique near the depletion layer along with minimizing impurity concentrations in Si. Such an upgraded capability of an extremely low-energy-ion detection with the low-noise characteristics enlarges research regimes of plasma-ion behavior using semiconductor detectors not only in the divertor regions of tokamaks but in wider spectra of open-field plasma devices including tandem mirrors. An application of the semiconductor ion detector for plasma-ion diagnostics is demonstrated in a specially designed ion-spectrometer structure.

  15. Measurement of neutron flux distribution by semiconductor detector

    International Nuclear Information System (INIS)

    Obradovic, D.; Bosevski, T.

    1964-01-01

    Application of semiconductor detectors for measuring neutron flux distribution is about 10 times faster than measurements by activation foils and demands significantly lower reactor power. Following corrections are avoided: mass of activation foils which influences the self shielding, nuclear decay during activity measurements; counter dead-time. It is possible to control the measured data during experiment and repeat measurements if needed. Precision of the measurement is higher since it is possible to choose the wanted statistics. The method described in this paper is applied for measurements at the RB reactor. It is concluded that the method is suitable for fast measurements but the activation analysis is still indispensable

  16. Neutron detection with cryogenics and semiconductors

    International Nuclear Information System (INIS)

    Bell, Zane W.; Carpenter, D.A.; Cristy, S.S.; Lamberti, V.E.; Burger, Arnold; Woodfield, Brian F.; Niedermayr, Thomas; Dragos Hau, I.; Labov, Simon E.; Friedrich, Stephan; Geoffrey West, W.; Pohl, Kenneth R.; Berg, Lodewijk van den

    2005-01-01

    The common methods of neutron detection are reviewed with special attention paid to the application of cryogenics and semiconductors to the problem. The authors' work with LiF- and boron-based cryogenic instruments is described as well as the use of CdTe and HgI 2 for direct detection of neutrons. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Response function and optimum configuration of semiconductor backscattered-electron detectors for scanning electron microscopes

    International Nuclear Information System (INIS)

    Rau, E. I.; Orlikovskiy, N. A.; Ivanova, E. S.

    2012-01-01

    A new highly efficient design for semiconductor detectors of intermediate-energy electrons (1–50 keV) for application in scanning electron microscopes is proposed. Calculations of the response function of advanced detectors and control experiments show that the efficiency of the developed devices increases on average twofold, which is a significant positive factor in the operation of modern electron microscopes in the mode of low currents and at low primary electron energies.

  18. 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.

  19. Evaluation of the quality of semi-insulating CdTe for radiation detectors by measurement of lux-ampere characteristics

    International Nuclear Information System (INIS)

    Franc, J.; Kubat, J.; Grill, R.; Dedic, V.; Hlidek, P.; Moravec, P.; Belas, E.

    2011-01-01

    Accumulation of space charge on deep levels represents one of the major problems in fabrication of semi-insulating CdTe and CdZnTe X-ray and gamma-ray detectors, because it influences the applied electric field and can even result in a complete breakdown of the field in part of the sample (polarization and dead layer formation). The goal of the study was to evaluate possibilities of localization of areas of potential space charge accumulation in as grown crystals by steady state measurement of lux-ampere characteristics. All measurements were done at room temperature using He-Ne laser. Voltage was applied parallel to the direction of light propagation in the range 10-100 V. It was observed that all lux-ampere characteristics are sub-linear. Screening effects caused by space charge accumulated on deep levels explain these results. Crystals prepared by Vertical gradient freeze method in our laboratory are compared to a commercially available detector-grade sample prepared by Travelling heater method. Comparison of crystals grown from precursors of different starting purity shows an increase of the slope of lux-ampere characteristics with a decrease of impurity content. A correlation between the slope of lux-ampere characteristics and the mobility-lifetime product of electrons was observed, too.

  20. Evaluation of the quality of semi-insulating CdTe for radiation detectors by measurement of lux-ampere characteristics

    Science.gov (United States)

    Franc, J.; Kubát, J.; Grill, R.; Dědič, V.; Hlídek, P.; Moravec, P.; Belas, E.

    2011-05-01

    Accumulation of space charge on deep levels represents one of the major problems in fabrication of semi-insulating CdTe and CdZnTe X-ray and gamma-ray detectors, because it influences the applied electric field and can even result in a complete breakdown of the field in part of the sample (polarization and dead layer formation). The goal of the study was to evaluate possibilities of localization of areas of potential space charge accumulation in as grown crystals by steady state measurement of lux-ampere characteristics. All measurements were done at room temperature using He-Ne laser. Voltage was applied parallel to the direction of light propagation in the range 10-100 V. It was observed that all lux-ampere characteristics are sub-linear. Screening effects caused by space charge accumulated on deep levels explain these results. Crystals prepared by Vertical gradient freeze method in our laboratory are compared to a commercially available detector-grade sample prepared by Travelling heater method. Comparison of crystals grown from precursors of different starting purity shows an increase of the slope of lux-ampere characteristics with a decrease of impurity content. A correlation between the slope of lux-ampere characteristics and the mobility-lifetime product of electrons was observed, too.

  1. 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...

  2. Evaluation of a method for determination of the subcutaneous blood flow in the forefoot continuously over 24 h

    DEFF Research Database (Denmark)

    Jelnes, Rolf; Bülow, J

    1984-01-01

    A method is presented which allows for continuous registration of forefoot blood flow over 24 h. Blood flow was estimated by the radioactive Xenon washout method and a portable CdTe detector system was used to measure the tracer disappearance rate. Since the semiconductor detector is placed very ...

  3. Study of surface modifications for improved selected metal (II-VI) semiconductor based devices

    Science.gov (United States)

    Blomfield, Christopher James

    Metal-semiconductor contacts are of fundamental importance to the operation of all semiconductor devices. There are many competing theories of Schottky barrier formation but as yet no quantitative predictive model exists to adequately explain metal-semiconductor interfaces. The II-VI compound semiconductors CdTe, CdS and ZnSe have recently come to the fore with the advent of high efficiency photovoltaic cells and short wavelength light emitters. Major problems still exist however in forming metal contacts to these materials with the desired properties. This work presents results which make a significant contribution to the theory of metal/II-VI interface behaviour in terms of Schottky barriers to n-type CdTe, CdS and ZnSe.Predominantly aqueous based wet chemical etchants were applied to the surfaces of CdTe, CdS and ZnSe which were subsequently characterised by X-ray photoelectron spectroscopy. The ionic nature of these II-VI compounds meant that they behaved as insoluble salts of strong bases and weak acids. Acid etchants induced a stoichiometric excess of semiconductor anion at the surface which appeared to be predominantly in the elemental or hydrogenated state. Alkaline etchants conversely induced a stoichiometric excess of semiconductor cation at the surface which appeared to be in an oxidised state.Metal contacts were vacuum-evaporated onto these etched surfaces and characterised by current-voltage and capacitance-voltage techniques. The surface preparation was found to have a clear influence upon the electrical properties of Schottky barriers formed to etched surfaces. Reducing the native surface oxide produced near ideal Schottky diodes. An extended study of Au, Ag and Sb contacts to [mathematical formula] substrates again revealed the formation of several discrete Schottky barriers largely independent of the metal used; for [mathematical formula]. Deep levels measured within this study and those reported in the literature led to the conclusion that Fermi

  4. 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

  5. Charge separation and transfer in hybrid type II tunneling structures of CdTe and CdSe nanocrystals

    International Nuclear Information System (INIS)

    Gross, Dieter Konrad Michael

    2013-01-01

    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

  6. Detectors - Electronics

    International Nuclear Information System (INIS)

    Bregeault, J.; Gabriel, J.L.; Hierle, G.; Lebotlan, P.; Leconte, A.; Lelandais, J.; Mosrin, P.; Munsch, P.; Saur, H.; Tillier, J.

    1998-01-01

    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 → e - 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 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

  7. Performance and operation experience of the Atlas Semiconductor Tracker and Pixel Detector at the LHC.

    CERN Document Server

    Stanecka, E; The ATLAS collaboration

    2013-01-01

    After more than 3 years of successful operation at the LHC, we report on the operation and performance of the ATLAS Pixel Detector and Semi-Conductor Tracker (SCT) functioning in a high luminosity, high radiation environment.

  8. Synthesis and characterization of CdTe nanostructures grown by RF magnetron sputtering method

    Science.gov (United States)

    Akbarnejad, Elaheh; Ghoranneviss, Mahmood; Hantehzadeh, Mohammad Reza

    2017-08-01

    In this paper, we synthesize Cadmium Telluride nanostructures by radio frequency (RF) magnetron sputtering system on soda lime glass at various thicknesses. The effect of CdTe nanostructures thickness on crystalline, optical and morphological properties has been studied by means of X-ray diffraction (XRD), UV-VIS-NIR spectrophotometry, field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), respectively. The XRD parameters of CdTe nanostructures such as microstrain, dislocation density, and crystal size have been examined. From XRD analysis, it could be assumed that increasing deposition time caused the formation of the wurtzite hexagonal structure of the sputtered films. Optical properties of the grown nanostructures as a function of film thickness have been observed. All the films indicate more than 60% transmission over a wide range of wavelengths. The optical band gap values of the films have obtained in the range of 1.62-1.45 eV. The results indicate that an RF sputtering method succeeded in depositing of CdTe nanostructures with high purity and controllable physical properties, which is appropriate for photovoltaic and nuclear detector applications.

  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. The system of digital-image optical microscope in semiconductor particle detector development

    International Nuclear Information System (INIS)

    Han Lixiang; Li Zhankui; Jin Genming; Wang Zhusheng; Xiao Guoqing

    2009-01-01

    Optical microscopic detection is very important in the process of semiconductor particle detector development. A system of digital-image optical microscope has been constructed with rather low price, which performance is comparable with the moderate-level imports. The system mounts powerful dry objective, and a 2μm resolution could be achieved. Observations with bright and dark field, polarized light,and interference light can be carried out on it. The system have large area on-line monitor,and the photographic device can be controlled by PC. It can be used in the control of defects and contaminations, pattern test, identification of crystal backing, inspection of the smoothness and the flatness of the crystal surface. It can also be used in some precise procedures, such as test, assembly, packaging and repairing. The quality of the bond could be examined by observing the appearance of the bond point and the microscopic structure of the solder. The surface fluctuation can be precisely measured under the microscope with the technology of multi-beam interference. In the article, the application of this system for semiconductor particle detector development has been illustrated, and the construction information has been described in detail. (authors)

  11. Development of a high sensitivity pinhole type gamma camera using semiconductors for low dose rate fields

    Science.gov (United States)

    Ueno, Yuichiro; Takahashi, Isao; Ishitsu, Takafumi; Tadokoro, Takahiro; Okada, Koichi; Nagumo, Yasushi; Fujishima, Yasutake; Yoshida, Akira; Umegaki, Kikuo

    2018-06-01

    We developed a pinhole type gamma camera, using a compact detector module of a pixelated CdTe semiconductor, which has suitable sensitivity and quantitative accuracy for low dose rate fields. In order to improve the sensitivity of the pinhole type semiconductor gamma camera, we adopted three methods: a signal processing method to set the discriminating level lower, a high sensitivity pinhole collimator and a smoothing image filter that improves the efficiency of the source identification. We tested basic performances of the developed gamma camera and carefully examined effects of the three methods. From the sensitivity test, we found that the effective sensitivity was about 21 times higher than that of the gamma camera for high dose rate fields which we had previously developed. We confirmed that the gamma camera had sufficient sensitivity and high quantitative accuracy; for example, a weak hot spot (0.9 μSv/h) around a tree root could be detected within 45 min in a low dose rate field test, and errors of measured dose rates with point sources were less than 7% in a dose rate accuracy test.

  12. Origin of the Distinct Diffusion Behaviors of Cu and Ag in Covalent and Ionic Semiconductors.

    Science.gov (United States)

    Deng, Hui-Xiong; Luo, Jun-Wei; Li, Shu-Shen; Wei, Su-Huai

    2016-10-14

    It is well known that Cu diffuses faster than Ag in covalent semiconductors such as Si, which has prevented the replacement of Ag by Cu as a contact material in Si solar cells for reducing the cost. Surprisingly, in more ionic materials such as CdTe, Ag diffuses faster than Cu despite that it is larger than Cu, which has prevented the replacement of Cu by Ag in CdTe solar cells to improve the performance. But, so far, the mechanisms behind these distinct diffusion behaviors of Cu and Ag in covalent and ionic semiconductors have not been addressed. Here we reveal the underlying mechanisms by combining the first-principles calculations and group theory analysis. We find that the symmetry controlled s-d coupling plays a critical role in determining the diffusion behaviors. The s-d coupling is absent in pure covalent semiconductors but increases with the ionicity of the zinc blende semiconductors, and is larger for Cu than for Ag, owing to its higher d orbital energy. In conjunction with Coulomb interaction and strain energy, the s-d coupling is able to explain all the diffusion behaviors from Cu to Ag and from covalent to ionic hosts. This in-depth understanding enables us to engineer the diffusion of impurities in various semiconductors.

  13. Development of novel semiconductor detectors for the detection of ionizing radiation

    International Nuclear Information System (INIS)

    Strueder, L.

    1989-08-01

    The present thesis treats the development of novel energy- and position-resolving semiconductor detectors: Fully depletable pn CCD's. In experiments of high-energy physics they are suited as highly resolving position-sensitive detectors for minimally ionizing particles. In nuclear and atomic physics they can be applied as position-resolving energy spectrometers. Increasing interest detectors of this type find also at synchrotron-radiation sources with photon energies from 20 eV to 50 keV. As focal instruments of X-ray telescopes they are in astrophysical measurements in an energy range from 100 eV to 15 keV of use. The required accuracy in the energy measurement amounts to 100 eV (FWHM) at an X-ray energy of 1 keV, at a simultaneous precision of the position determination of 50 μm. The measurement results which are here presented on the first fully depletable CCD's show that the components posses the potential to fulfill these requirements. (orig.) [de

  14. New imaging spectrometer CdTe very high spatial and spectral resolution for X and gamma astronomy

    International Nuclear Information System (INIS)

    Dubos, Sebastien

    2015-01-01

    The thesis work presented in this manuscript corresponds to the first development phase of the MC2 project, an ambitious R and D effort to realize a new type of cadmium telluride (CdTe) -based imaging spectrometer for future hard X- and gamma-rays astronomy missions. The final goal is to achieve a 300 micron-pitch pixelated detector plane hybridized with a very low noise front-end electronics for a total pixel density multiplied by 4 compared to the most advanced System recently available in the laboratory, the Caliste HD imaging spectrometer. Moreover, thanks to the joint development of readout circuits adapted to the interconnection of pixelated detectors with low capacitance and low leakage current, spectroscopic performances of such system are assumed to approach inherent limitations of the CdTe detector, especially for the lowest energies. The work was organized in parallel and complementary areas: evaluation of current Systems, feedback and identification of issues associated with the development of highly-resolved detection planes, implementation and complete characterization of a new two-dimensional ASIC specifically developed for this application, and modeling and study of the associated sensor to optimize the design of the detector pattern. Finally, a first hybrid prototype was completed and first experimental tests thereby conducted. (author) [fr

  15. Surface passivation for CdTe devices

    Energy Technology Data Exchange (ETDEWEB)

    Reese, Matthew O.; Perkins, Craig L.; Burst, James M.; Gessert, Timothy A.; Barnes, Teresa M.; Metzger, Wyatt K.

    2017-08-01

    In one embodiment, a method for surface passivation for CdTe devices is provided. The method includes adjusting a stoichiometry of a surface of a CdTe material layer such that the surface becomes at least one of stoichiometric or Cd-rich; and reconstructing a crystalline lattice at the surface of the CdTe material layer by annealing the adjusted surface.

  16. Influence of hydrostatic pressure on nuclear radiation detector's properties based on semiconductor alloy CdZnTe

    International Nuclear Information System (INIS)

    Kutnij, V.E.; Kutnij, D.V.; Rybka, A.V.; Nakonechnyj, D.V.; Babun, A.V.

    2003-01-01

    The influence of hydrostatic pressure on properties of CdZnTe semiconductor detectors (Cd-50,Zn-2,Te-48 mas.%, 5 centre dot 5 centre dot 2 mm) was investigated. Were considered different types of hydrostatic treatment at 100 MPa, second hydrostatic treatment at 100 MPa and 200 MPa. Hydrostatic pressure influence on detectors electric resistance, J-V characteristics and spectrometric parameters was determined

  17. Testing in a stratospheric balloon of a semiconductor detector altimeter

    International Nuclear Information System (INIS)

    Gilly, L.; Jourdan, P.

    1968-01-01

    An altimeter containing a semiconductor detector has been operated on flight. We have used a stratospheric balloon launched from AIRE-SUR-ADOUR with the C.N.E.S. collaboration. During this assay two apparatus have been used. The first allowed to follow the balloon during its ascension and descent, the second to follow its evolution at its maximum altitude. Informations transmitted by radio and recorded on Magnetophon, have been studied after the flight. Results are identical with these given by the barometer used by the C.N.E.S. in this essay. (authors) [fr

  18. Semiconductor electrolyte photovoltaic energy converter

    Science.gov (United States)

    Anderson, W. W.; Anderson, L. B.

    1975-01-01

    Feasibility and practicality of a solar cell consisting of a semiconductor surface in contact with an electrolyte are evaluated. Basic components and processes are detailed for photovoltaic energy conversion at the surface of an n-type semiconductor in contact with an electrolyte which is oxidizing to conduction band electrons. Characteristics of single crystal CdS, GaAs, CdSe, CdTe and thin film CdS in contact with aqueous and methanol based electrolytes are studied and open circuit voltages are measured from Mott-Schottky plots and open circuit photo voltages. Quantum efficiencies for short circuit photo currents of a CdS crystal and a 20 micrometer film are shown together with electrical and photovoltaic properties. Highest photon irradiances are observed with the GaAs cell.

  19. Dosimetric evaluation of semiconductor detectors for application in neutron dosimetry and microdosimetry in nuclear reactor and radiosurgical facilities

    International Nuclear Information System (INIS)

    Cardenas, Jose Patricio Nahuel

    2010-01-01

    The main objective of this research is the dosimetric evaluation of semiconductor components (surface barrier detectors and PIN photodiodes) for applications in dose equivalent measurements on low dose fields (fast and thermal fluxes) using an AmBe neutron source, the IEA-R1 reactor neutrongraphy facility (epithermal and thermal fluxes) and the Critical Unit facility IPEN/MB-01 (fast fluxes). As moderator compound to fast neutrons flux from the AmBe source was used paraffin and boron and polyethylene as converter for thermal and fast neutrons measurements. The resulting fluxes were used to the irradiation of semiconductor components (SSB - Surface Barrier Detector and PIN photodiodes). A mixed converter made of a borated polyethylene foil (Kodak) was also used. Monte Carlo simulation methodology was employed to evaluate analytically the optimal paraffin thickness. The obtained results were similar to the experimental data and allowed the evaluation of emerging neutron flux from moderator, as well as the fast neutron flux reaching the polyethylene covering the semiconductor sensitive surface. Gamma radiation levels were evaluated covering the whole detector with cadmium foil 1 mm thick, allowing thermal neutrons blockage and gamma radiation measurements. The IPEN/MB-01 facility was employed to evaluate the detector response for high neutron flux. The results were in good agreement with other studies published. Using the obtained spectra an approach to dose equivalent calculation was established. (author)

  20. Alpha- and gamma-detection by the avalanche detectors with metal-resistor-semiconductor structure

    International Nuclear Information System (INIS)

    Vetokhin, S.S.; Evtushenko, V.P.; Zalesskij, V.B.; Malyshev, S.A.; Chudakov, V.A.; Shunevich, S.A.

    1992-01-01

    Possibility to use silicon avalanche photodetectors with metal-resistor-semiconductor structure with 0.12 cm 2 photosensitive area as detectors of α-particles, as well as, photodetector of γ-quanta scintillation detector is shown. When detection of α-particles the energy resolution reaches 10%. R energy resolution for avalanche photodetector-CsI(Tl) scintillator system cooled up to - 60 deg C at 59 keV ( 241 Am) and 662 keV ( 137 Cs) energy of γ-quanta constitutes 60% and 80%, respectively. R minimal value in the conducted experiments is determined by the degree of irregularity of avalanche amplification along the photodetector area

  1. 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.

  2. On selecting a sensitive region thickness of a silicon semiconductor detector for operation under counting conditions

    International Nuclear Information System (INIS)

    Pronkin, N.S.; Khakhalin, V.V.

    1972-01-01

    The paper discusses the selection of a thickness of a sensitive area of a silicon semiconductor detector, used in the count regime based on the signal to noise ratio and β-radiation registration efficiency. (author)

  3. Leakage current measurements on pixelated CdZnTe detectors

    International Nuclear Information System (INIS)

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

    2006-01-01

    In the field of the R and 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 (0.9x0.9 mm 2 ) or 256 (0.5x0.5 mm 2 ) pixels, surrounded by a guard ring and operate in the energy ranging from several keV to 1 MeV, at temperatures between -20 and +20 o C. A critical parameter in the characterisation of these detectors is the leakage current per pixel under polarisation (∼50-500 V/mm). In operation mode each pixel will be read-out by an integrated spectroscopy channel of the multi-channel IDeF-X ASIC currently developed in our lab. The design and functionality of the ASIC depends directly on the direction and value of the current. A dedicated and highly insulating electronics circuit is designed to automatically measure the current in each individual pixel, which is in the order of tens of pico-amperes. Leakage current maps of different CdZnTe detectors of 2 and 6 mm thick and at various temperatures are presented and discussed. Defect density diagnostics have been performed by calculation of the activation energy of the material

  4. Systematization of efficiency correction for gamma-ray disk sources with semiconductor detectors

    International Nuclear Information System (INIS)

    Chatani, Hiroshi

    1999-01-01

    Full energy peak efficiency correction for disk sources has been systematically studied using the mapping method with two high-purity germanium detectors and two low-energy photon spectrometers. The following are found using only single-line (i.e., no coincidence summing loses) γ-rays: (1) The efficiency distributions on a plane parallel to the entrance window of semiconductor detectors is in perfect accord with Gaussian curves inside the circumference of the cylindrical Ge crystal, however, they deviate from the curves outside the circumference. (2) The width parameters of the Gaussian function fitted to the efficiency distributions have a systematic relationship with γ-ray energy. (3) The mapping method is of practical use and has satisfactory accuracy

  5. Silicon radiation detectors

    International Nuclear Information System (INIS)

    Lutz, G.

    1995-01-01

    An introduction to and an overview of function principles and properties of semiconductor radiation detectors is attempted. The paper is addressed to people interested in detector development but not already experts in the field of semiconductor detectors. (orig.)

  6. Semiconductor scintillator detector for gamma radiation

    International Nuclear Information System (INIS)

    Laan, F.T.V. der; Borges, V.; Zabadal, J.R.S.

    2015-01-01

    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)

  7. Applications of CdTe to nuclear medicine. Annual report, February 1, 1979-January 31, 1980

    International Nuclear Information System (INIS)

    Entine, G.

    1980-01-01

    The application of CdTe gamma detectors in nuclear medicine is reported on. An internal probe was developed which can be inserted into the heart to measure the efficiency of various radiopharmaceuticals in the treatment of heart attacks. A second application is an array of detectors which is light enough to be worn by ambulatory patients and can measure the change in cardiac output over an eight hour period during heart attack treatment. The instrument includes an on board tape recorder

  8. 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.

  9. Comparison of Cadmium-Zinc-Telluride semiconductor and Yttrium-Aluminum-Perovskite scintillator as photon detectors for epithermal neutron spectroscopy

    International Nuclear Information System (INIS)

    Tardocchi, M.; Pietropaolo, A.; Andreani, C.; Gorini, G.; Imberti, S.; Perelli-Cippo, E.; Senesi, R.; Rhodes, N.; Schooneveld, E.M.

    2006-01-01

    The range of applications of epithermal neutron scattering experiments has been recently extended by the development of the Resonance Detector. In a Resonance Detector, resonant neutron absorption in an analyzer foil results in prompt emission of X- and γ-rays which are detected by a photon counter. Several combinations of analyzer foils and photon detectors have been studied and tested over the years and best results have been obtained with the combination of a natural uranium and (i) Cadmium-Zinc-Telluride (CZT) semiconductor (ii) Yttrium-Aluminum-Perovskite (YAP) scintillators. Here we compare the performance of the CZT semiconductor and YAP scintillator as Resonance Detector units. Two Resonance Detector prototypes made of natural uranium foil viewed by CZT and YAP were tested on the VESUVIO spectrometer at the ISIS spallation neutron source. The results show that both YAP and CZT can be used to detect epithermal neutrons in the energy range from 1 up to 66 eV. It was found that the signal-to-background ratio of the measurement can significantly be improved by raising the lower level discrimination threshold on the γ energy to about 600 keV. The advantages/disadvantages of the choice of a Resonance Detector based on YAP or CZT are discussed together with some potential applications

  10. 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.

  11. Numerical dataset for analyzing the performance of a highly efficient ultrathin film CdTe solar cell

    Directory of Open Access Journals (Sweden)

    Rucksana Safa Sultana

    2017-06-01

    Full Text Available The article comprises numerical data of distinct semiconductor materials applied in the sketch of a CdTe absorber based ultrathin film solar cell. Additionally, the contact layer parametric values of the cell have been described also. Therefore, the simulation has been conducted with data related to the hetero-structured (n-ZnO/n-CdS/p-CdTe/p-ZnTe semiconductor device and a J–V characteristics curve was obtained. The operating conditions have also been recorded. Afterward, the solar cell performance parameters such as open circuit voltage (Voc, short circuit current density (Jsc, fill factor (FF, and efficiency (η have been investigated and compared with reference cell.

  12. Response function of semiconductor detectors, Ge and Si(Li)

    International Nuclear Information System (INIS)

    Zevallos Chavez, Juan Yury

    2003-01-01

    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 3 , 50 cm 3 , 8 cm 3 and 5 cm 3 , and one Si(Li) with 0.143 cm 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)

  13. Semiconductor X-ray spectrometers

    International Nuclear Information System (INIS)

    Muggleton, A.H.F.

    1978-02-01

    An outline is given of recent developments in particle and photon induced x-ray fluorescence (XRF) analysis. Following a brief description of the basic mechanism of semiconductor detector operation a comparison is made between semiconductor detectors, scintillators and gas filled proportional devices. Detector fabrication and cryostat design are described in more detail and the effects of various device parameters on system performance, such as energy resolution, count rate capability, efficiency, microphony, etc. are discussed. The main applications of these detectors in x-ray fluorescence analysis, electron microprobe analysis, medical and pollution studies are reviewed

  14. Advanced crystal growth techniques for thallium bromide semiconductor radiation detectors

    Science.gov (United States)

    Datta, Amlan; Becla, Piotr; Guguschev, Christo; Motakef, Shariar

    2018-02-01

    Thallium Bromide (TlBr) is a promising room-temperature radiation detector candidate with excellent charge transport properties. Currently, Travelling Molten Zone (TMZ) technique is widely used for growth of semiconductor-grade TlBr crystals. However, there are several challenges associated with this type of crystal growth process including lower yield, high thermal stress, and low crystal uniformity. To overcome these shortcomings of the current technique, several different crystal growth techniques have been implemented in this study. These include: Vertical Bridgman (VB), Physical Vapor Transport (PVT), Edge-defined Film-fed Growth (EFG), and Czochralski Growth (Cz). Techniques based on melt pulling (EFG and Cz) were demonstrated for the first time for semiconductor grade TlBr material. The viability of each process along with the associated challenges for TlBr growth has been discussed. The purity of the TlBr crystals along with its crystalline and electronic properties were analyzed and correlated with the growth techniques. Uncorrected 662 keV energy resolutions around 2% were obtained from 5 mm x 5 mm x 10 mm TlBr devices with virtual Frisch-grid configuration.

  15. 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.

  16. Detector applications

    International Nuclear Information System (INIS)

    Pehl, R.H.

    1977-10-01

    Semiconductor detectors are now applied to a very wide range of problems. The combination of relatively low cost, excellent energy resolution, and simultaneous broad energy-spectrum analysis is uniquely suited to many applications in both basic and applied physics. Alternative techniques, such as magnetic spectrometers for charged-particle spectroscopy, while offering better energy resolution, are bulky, expensive, and usually far more difficult to use. Furthermore, they do not directly provide the broad energy-spectrum measurements easily accomplished using semiconductor detectors. Scintillation detectors, which are approximately equivalent to semiconductor detectors in convenience and cost, exhibit 10 to 100 times worse energy resolution. However, their high efficiency and large potential size recommend their use in some measurements

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

    Science.gov (United States)

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

    2015-10-01

    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 digital converter (ADC), configuration registers, and a 4-state digital controller. For every detected photon, the pixel electronics provides the energy deposited in the detector with 10-bit resolution, and a fast trigger signal for time stamp. The ASIC contains the 16-pixel matrix electronics, a digital controller, five global voltage references, a TDC, a temperature sensor, and a band-gap based current reference. The ASIC has been fabricated with TSMC 0.25 μ m mixed-signal CMOS technology and occupies an area of 5.3 mm × 6.8 mm. The TDC shows a resolution of 95.5 ps, a precision of 600 ps at full width half maximum (FWHM), and a power consumption of 130 μ W. In acquisition mode, the total power consumption of every pixel is 200 μ W. An equivalent noise charge (ENC) of 160 e - RMS at maximum gain and negative polarity conditions has been measured at room temperature.

  18. Detection of radioactivity by semiconductors

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    The class of detectors discussed in this chapter has a responsive component involving a diode, a junction between two types of semiconductor materials. Although diode detectors are not particularly efficient in counting radioactive emissions, they are superior to other commercially available detectors in spectroscopy. Consequently, diode detectors are used extensively for quanlitative purposes and for quantitative purposes when mixtures of radionuclides are present, not the usual situation with biological or medical research. Topics addressed in this chapter are as follows: Band Theory; Semiconductors and Junctions; and Radiation Detectors. 6 refs., 14 figs

  19. Caliste 64, an innovative CdTe hard X-ray micro-camera

    International Nuclear Information System (INIS)

    Meuris, A.; Limousin, O.; Pinsard, F.; Le Mer, I.; Lugiez, F.; Gevin, O.; Delagnes, E.; Vassal, M.C.; Soufflet, F.; Bocage, R.

    2008-01-01

    A prototype 64 pixel miniature camera has been designed and tested for the Simbol-X hard X-ray observatory to be flown on the joint CNES-ASI space mission in 2014. This device is called Caliste 64. It is a high performance spectro-imager with event time-tagging capability, able to detect photons between 2 keV and 250 keV. Caliste 64 is the assembly of a 1 or 2 min thick CdTe detector mounted on top of a readout module. CdTe detectors equipped with Aluminum Schottky barrier contacts are used because of their very low dark current and excellent spectroscopic performance. Front-end electronics is a stack of four IDeF-X V1.1 ASICs, arranged perpendicular to the detection plane, to read out each pixel independently. The whole camera fits in a 10 * 10 * 20 mm 3 volume and is juxtaposable on its four sides. This allows the device to be used as an elementary unit in a larger array of Caliste 64 cameras. Noise performance resulted in an ENC better than 60 electrons rms in average. The first prototype camera is tested at -10 degrees C with a bias of -400 V. The spectrum summed across the 64 pixels results in a resolution of 697 eV FWHM at 13.9 keV and 808 eV FWFM at 59.54 keV. (authors)

  20. CdTe aggregates in KBr crystalline matrix

    International Nuclear Information System (INIS)

    Bensouici, A.; Plaza, J.L.; Dieguez, E.; Halimi, O.; Boudine, B.; Addala, S.; Guerbous, L.; Sebais, M.

    2009-01-01

    In this work, we report the experimental results on the fabrication and optical characterization of Czochralski (Cz) grown KBr single crystals doped with CdTe crystallites. The results of the optical absorption have shown two bands, the first one located at 250 nm demonstrates the incorporation of cadmium atoms in the KBr host followed by a partial chemical decomposition of CdTe, the second band located at 585 nm shows an optical response of CdTe aggregates. Photoluminescence spectra at room temperature before annealing showed a band located at 520 nm (2.38 eV), with a blue shift from the bulk gap of 0.82 eV (E g (CdTe)=1.56 eV). While the photoluminescence spectra after annealing at 600 deg. C showed a band situated at 640 nm (1.93 eV), these bands are due to band-to-band transitions of CdTe nanocrystals with a blue shift from the bulk gap at 0.38 eV. Blue shift in optical absorption and photoluminescence spectra confirm nanometric size of dopant. X-ray diffraction (XRD) spectra have shown the incorporation of CdTe aggregates in KBr.

  1. CdTe aggregates in KBr crystalline matrix

    Energy Technology Data Exchange (ETDEWEB)

    Bensouici, A., E-mail: bensouicia@yahoo.f [Laboratory of Crystallography, Department of Physics, Mentouri-Constantine University, Constantine 25000 (Algeria); Plaza, J.L., E-mail: joseluis.plaza@uam.e [Crystal Growth Laboratory (CGL), Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Madrid (Spain); Dieguez, E. [Crystal Growth Laboratory (CGL), Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Madrid (Spain); Halimi, O.; Boudine, B.; Addala, S. [Laboratory of Crystallography, Department of Physics, Mentouri-Constantine University, Constantine 25000 (Algeria); Guerbous, L. [Centre de recherche nucleaire d' Alger (CRNA), Alger 16000 (Algeria); Sebais, M. [Laboratory of Crystallography, Department of Physics, Mentouri-Constantine University, Constantine 25000 (Algeria)

    2009-09-15

    In this work, we report the experimental results on the fabrication and optical characterization of Czochralski (Cz) grown KBr single crystals doped with CdTe crystallites. The results of the optical absorption have shown two bands, the first one located at 250 nm demonstrates the incorporation of cadmium atoms in the KBr host followed by a partial chemical decomposition of CdTe, the second band located at 585 nm shows an optical response of CdTe aggregates. Photoluminescence spectra at room temperature before annealing showed a band located at 520 nm (2.38 eV), with a blue shift from the bulk gap of 0.82 eV (E{sub g} (CdTe)=1.56 eV). While the photoluminescence spectra after annealing at 600 deg. C showed a band situated at 640 nm (1.93 eV), these bands are due to band-to-band transitions of CdTe nanocrystals with a blue shift from the bulk gap at 0.38 eV. Blue shift in optical absorption and photoluminescence spectra confirm nanometric size of dopant. X-ray diffraction (XRD) spectra have shown the incorporation of CdTe aggregates in KBr.

  2. 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.

  3. New developments in clinical applications of CdTe and CdZnTe detectors

    International Nuclear Information System (INIS)

    Scheiber, C.

    1996-01-01

    This review about the medical applications of CdTe and CdZnTe is an update on the 1992 paper (1992). This new paper is legitimized by the recent progress which has been made in this field. First of all, the usefulness of a new material, i.e. CdZnTe, has been demonstrated. While the two materials are still being improved, it seems as yet too early to debate which of CdTe:Cl or CdZnTe will be the best choice. Historical applications span over the past 18 years, involving devices like miniature probes for per-operative scintigraphy or the monitoring of physiological functions and, closer to us, appliances dedicated to bone densitometry, and have been expanding as such devices have become commercially available, for many years now. Newly available microelectronic circuitry allows 2D-arrays to be built for digital quantitative X-ray (chest, dental..) and for high-resolution gamma cameras. The clinical demand is very high, especially in the field of nuclear medicine. Although there already exist clinical demonstrators, the future of such CdTe applications depends on further reduction in material and device mounting costs. New perspectives concern XCT applications, but the data resulting from research work are kept for restricted use within industrial R and D laboratories. (orig.)

  4. 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

  5. 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

  6. Spectrometer based on the silicon semiconductor detectors for a study of the two charged particles correlation

    International Nuclear Information System (INIS)

    Krumsztein, Z.W.; Siemiarczuk, T.; Szawlowski, M.

    1974-01-01

    The spectrometer based on the silicon semiconductor detectors for a study of the correlation between two charged particles is described. The results of the time resolution and particles identification measurements are presented. The tests were performed in the proton beam of the JINR synchrocyclotron. (author)

  7. A proposal for both plasma ion- and electron-temperature diagnostics under simultaneous incidence of particles and x-rays into a semiconductor on the basis of a proposed model for a semiconductor detector response

    International Nuclear Information System (INIS)

    Numakura, T; Cho, T; Kohagura, J; Hirata, M; Minami, R; Yoshida, M; Nakashima, Y; Tamano, T; Yatsu, K; Miyoshi, S

    2003-01-01

    A method is proposed for obtaining radial profiles of plasma temperatures of both plasma ion (T i ) and electron (T e ) simultaneously by the use of a semiconductor detector array. The method is based on our developed particle-response model for a semiconductor detector; in particular, the response theory is constructed for giving the applicability in particle energies ranging down to a kiloelectronvolt. Calculated results from our model are in fairly good agreement with experimental data on the detector response of incident particle beams with energies in the range 100 eV to a few kiloelectronvolts. On the basis of the verification of the proposed model, an idea of the use of a developed semiconductor detector array covered with 'reliably unbreakable' ultrathin SiO 2 'dead-layer filters' having various nanometre-order thicknesses is applied for simultaneous T i and T e analyses by using charge-exchange neutral particles and x-rays from plasmas. Radial profiles of T i and T e are obtained in a single plasma discharge alone, and the data reliability is independently cross-checked by a radial scan of a conventional charge-exchange neutral-particle analyser system as well as a 50-channel microchannel plate x-ray diagnostics system in the GAMMA 10 tandem mirror

  8. Radiation effects on II-VI compound-based detectors

    CERN Document Server

    Cavallini, A; Dusi, W; Auricchio, N; Chirco, P; Zanarini, M; Siffert, P; Fougeres, P

    2002-01-01

    The performance of room temperature CdTe and CdZnTe detectors exposed to a radiation source can be strongly altered by the interaction of the ionizing particles and the material. Up to now, few experimental data are available on the response of II-VI compound detectors to different types of radiation sources. We have carried out a thorough investigation on the effects of gamma-rays, neutrons and electron irradiation both on CdTe : Cl and Cd sub 0 sub . sub 9 Zn sub 0 sub . sub 1 Te detectors. We have studied the detector response after radiation exposure by means of dark current measurements and of quantitative spectroscopic analyses at low and medium energies. The deep traps present in the material have been characterized by means of PICTS (photo-induced current transient spectroscopy) analyses, which allow to determine the trap apparent activation energy and capture cross-section. The evolution of the trap parameters with increasing irradiation doses has been monitored for all the different types of radiati...

  9. Design and test of a prototype silicon detector module for ATLAS Semiconductor Tracker endcaps

    International Nuclear Information System (INIS)

    Clark, A.G.; Donega, M.; D'Onofrio, M.

    2005-01-01

    The ATLAS Semiconductor Tracker (SCT) will be a central part of the tracking system of the ATLAS experiment. The SCT consists of four concentric barrels of silicon detectors as well as two silicon endcap detectors formed by nine disks each. The layout of the forward silicon detector module presented in this paper is based on the approved layout of the silicon detectors of the SCT, their geometry and arrangement in disks, but uses otherwise components identical to the barrel modules of the SCT. The module layout is optimized for excellent thermal management and electrical performance, while keeping the assembly simple and adequate for a large scale module production. This paper summarizes the design and layout of the module and present results of a limited prototype production, which has been extensively tested in the laboratory and testbeam. The module design was not finally adopted for series production because a dedicated forward hybrid layout was pursued

  10. Radiation detectors

    International Nuclear Information System (INIS)

    2013-01-01

    This sixth chapter presents the operational principles of the radiation detectors; detection using photographic emulsions; thermoluminescent detectors; gas detectors; scintillation detectors; liquid scintillation detectors; detectors using semiconductor materials; calibration of detectors; Bragg-Gray theory; measurement chain and uncertainties associated to measurements

  11. Semidetector-radiation detector arrangement, as well as its application in a tomographic scanner, in a device to determine radiation intensity or to measure the radiation penetration or absorption

    International Nuclear Information System (INIS)

    Kaufman, L.; Hosier, K.E. Jr.

    1979-01-01

    The CdTe detector or a plate with several CdTe or HgI 2 detectors is suitable for use in computer controlled tomographic X-ray scanners. The detector is used in connection with a pulsed radiation source (Am 241) and a frequency filter technique for measuring the resulting electrical charge pulse of the detector. Merely a narrow frequency band is selected according to the measured duration of the incident radiation pulses. (DG) [de

  12. 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.

  13. Wide Bandgap Semiconductor Detector Optimization for Flash X-Ray Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Roecker, Caleb Daniel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schirato, Richard C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-17

    Charge trapping, resulting in a decreased and spatially dependent electric field, has long been a concern for wide bandgap semiconductor detectors. While significant work has been performed to characterize this degradation at varying temperatures and radiation environments, this work concentrates upon examining the event-to-event response in a flash X-ray environment. The following work investigates if charge trapping is a problem for CZT detectors, with particular emphasis on flash X-ray radiation fields at cold temperatures. Results are compared to a non-flash radiation field, using an Am-241 alpha source and similar temperature transitions. Our ability to determine if a response change occurred was hampered by the repeatability of our flash X-ray systems; a small response change was observed with the Am-241 source. Due to contrast of these results, we are in the process of revisiting the Am-241 measurements in the presence of a high radiation environment. If the response change is more pronounced in the high radiation environment, a similar test will be performed in the flash X-ray environment.

  14. A comparison between the response of compound semiconductor detectors in single and back-to-back configuration

    International Nuclear Information System (INIS)

    Auricchio, N.; Donati, A.; Dusi, W.; Perillo, E.; Siffert, P.

    2004-01-01

    CdTe detectors (3 x 5 mm 2 electrode area and 1 mm thick), mounted in a back-to-back configuration with common anode, have been characterized, aiming at determining the actual regions of these devices giving the best and almost constant spectroscopic performance. This configuration ensures that the maximum paths of the charge carriers correspond to the inter-electrode distances and consequently the spectroscopic performance is essentially the same as for the single coupled detectors, but allows one: - to double the useful absorbing thickness when irradiated in the classical planar parallel field geometry; - to double the pixel area when irradiated in the planar transverse field (PTF) geometry, while the absorbing thickness can be freely adjusted according to the experimental requirements. The tests were performed in PTF geometry by using well collimated photon beams (10-300 keV energy range) obtained by a 20 mm thick tungsten collimator having a 0.1 x 1 or a 0.3 x 1 mm 2 collimating channel. Experimental results concerning the spectroscopic behaviour of the coupled detectors have been compared with those obtained by single devices having the same thickness as the single components or the same total thickness as the coupled device. The results show that the back-to-back configuration does not introduce further significant noise with respect to 1 mm thick single detectors and their spectroscopic performance is similar or better than the one shown by 2 mm thick single devices for fine and wide collimator measurements, and mostly in the uncollimated case

  15. Photosensitive space charge limited current in screen printed CdTe thin films

    Science.gov (United States)

    Vyas, C. U.; Pataniya, Pratik; Zankat, Chetan K.; Patel, Alkesh B.; Pathak, V. M.; Patel, K. D.; Solanki, G. K.

    2018-05-01

    Group II-VI Compounds have emerged out as most suitable in the class of photo sensitive material. They represent a strong position in terms of their applications in the field of detectors as well as photo voltaic devices. Cadmium telluride is the prime member of this Group, because of high acceptance of this material as active component in opto-electronic devices. In this paper we report preparation and characterization of CdTe thin films by using a most economical screen printing technique in association with sintering at 510°C temperature. Surface morphology and smoothness are prime parameters of any deposited to be used as an active region of devices. Thus, we studied of the screen printed thin film by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM) for this purpose. However, growth processes induced intrinsic defects in fabricated films work as charge traps and affect the conduction process significantly. So the conduction mechanism of deposited CdTe thin film is studied under dark as well as illuminated conditions. It is found that the deposited films showed the space charge limited conduction (SCLC) mechanism and hence various parameters of space charge limited conduction (SCLC) of CdTe film were evaluated and discussed and the photo responsive resistance is also presented in this paper.

  16. Unified Numerical Solver for Device Metastabilities in CdTe Thin-Film PV

    Energy Technology Data Exchange (ETDEWEB)

    Vasileska, Dragica [Arizona State Univ., Tempe, AZ (United States)

    2017-08-17

    Thin-film modules of all technologies often suffer from performance degradation over time. Some of the performance changes are reversible and some are not, which makes deployment, testing, and energy-yield prediction more challenging. Manufacturers de-vote significant empirical efforts to study these phenomena and to improve semiconduc-tor device stability. Still, understanding the underlying reasons of these instabilities re-mains clouded due to the lack of ability to characterize materials at atomistic levels and the lack of interpretation from the most fundamental material science. The most com-monly alleged causes of metastability in CdTe device, such as “migration of Cu,” have been investigated rigorously over the past fifteen years. Still, the discussion often ended prematurely with stating observed correlations between stress conditions and changes in atomic profiles of impurities or CV doping concentration. Multiple hypotheses sug-gesting degradation of CdTe solar cell devices due to interaction and evolution of point defects and complexes were proposed, and none of them received strong theoretical or experimental confirmation. It should be noted that atomic impurity profiles in CdTe pro-vide very little intelligence on active doping concentrations. The same elements could form different energy states, which could be either donors or acceptors, depending on their position in crystalline lattice. Defects interact with other extrinsic and intrinsic de-fects; for example, changing the state of an impurity from an interstitial donor to a sub-stitutional acceptor often is accompanied by generation of a compensating intrinsic in-terstitial donor defect. Moreover, all defects, intrinsic and extrinsic, interact with the elec-trical potential and free carriers so that charged defects may drift in the electric field and the local electrical potential affects the formation energy of the point defects. Such complexity of interactions in CdTe makes understanding of

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

    International Nuclear Information System (INIS)

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

    1999-01-01

    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

  18. Development and application of nuclear radiation detector made from high resistivity silicon and compound semiconductor

    International Nuclear Information System (INIS)

    Ding Honglin; Zhang Xiufeng; Zhang Wanchang; Li Jiang

    1995-11-01

    The development of high resistivity silicon detectors and compound semiconductor detectors as well as their application in nuclear medicine are described. It emphasizes on several key techniques in fabricating detectors in order to meet their application in nuclear medicine. As for a high resistivity silicon detector, its counting rate to 125 I 28.5 keV X-ray has to be improved. So employing a conic mesa structure can increase the thickness of samples, and can raise the electric field of collecting charges under the same bias voltage. As for a GaAs detector, its performance of collecting charges has to be improved. So the thicknesses of GaAs samples are decreased and proper thermal treatment to make Ni-Ge-Au ohmic contacts are employed. Applying a suitable reverse bias voltage can obtain a fully depleted detector, and can obtain a lower forward turn-on voltage and a thinner weak electric field region. After resolving these key techniques, the performance of GaAs detectors has been distinctly improved. The count rate to 125 I X-ray has increased by three or five times under the same testing condition and background circumstance (2 refs., 8 figs., 3 tabs.)

  19. 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.

  20. 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

  1. Caliste 64, an innovative CdTe hard X-ray micro-camera

    Energy Technology Data Exchange (ETDEWEB)

    Meuris, A.; Limousin, O.; Pinsard, F.; Le Mer, I. [CEA Saclay, DSM, DAPNIA, Serv. Astrophys., F-91191 Gif sur Yvette (France); Lugiez, F.; Gevin, O.; Delagnes, E. [CEA Saclay, DSM, DAPNIA, Serv. Electron., F-91191 Gif sur Yvette (France); Vassal, M.C.; Soufflet, F.; Bocage, R. [3D-plus Company, F-78532 Buc (France)

    2008-07-01

    A prototype 64 pixel miniature camera has been designed and tested for the Simbol-X hard X-ray observatory to be flown on the joint CNES-ASI space mission in 2014. This device is called Caliste 64. It is a high performance spectro-imager with event time-tagging capability, able to detect photons between 2 keV and 250 keV. Caliste 64 is the assembly of a 1 or 2 min thick CdTe detector mounted on top of a readout module. CdTe detectors equipped with Aluminum Schottky barrier contacts are used because of their very low dark current and excellent spectroscopic performance. Front-end electronics is a stack of four IDeF-X V1.1 ASICs, arranged perpendicular to the detection plane, to read out each pixel independently. The whole camera fits in a 10 * 10 * 20 mm{sup 3} volume and is juxtaposable on its four sides. This allows the device to be used as an elementary unit in a larger array of Caliste 64 cameras. Noise performance resulted in an ENC better than 60 electrons rms in average. The first prototype camera is tested at -10 degrees C with a bias of -400 V. The spectrum summed across the 64 pixels results in a resolution of 697 eV FWHM at 13.9 keV and 808 eV FWFM at 59.54 keV. (authors)

  2. 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.

  3. Multi electrode semiconductors detectors

    CERN Document Server

    Amendolia, S R; Bertolucci, Ennio; Bosisio, L; Bradaschia, C; Budinich, M; Fidecaro, F; Foà, L; Focardi, E; Giazotto, A; Giorgi, M A; Marrocchesi, P S; Menzione, A; Ristori, L; Rolandi, Luigi; Scribano, A; Stefanini, A; Vincelli, M L

    1981-01-01

    Detectors with very high space resolution have been built in this laboratory and tested at CERN in order to investigate their possible use in high energy physics experiments. These detectors consist of thin layers of silicon crystals acting as ionization chambers. Thin electrodes, structured in strips or in more fancy shapes are applied to their surfaces by metal coating. The space resolution which could be reached is of the order of a few microns. An interesting feature of these solid state detectors is that they can work under very high or low external pressure or at very low temperature. The use of these detectors would strongly reduce the dimensions and the cost of high energy experiments. (3 refs).

  4. Multi electrode semiconductor detectors

    International Nuclear Information System (INIS)

    Amendolia, S.R.; Batignani, G.; Bertolucci, E.; Bosisio, L.; Budinich, M.; Bradaschia, C.; Fidecaro, F.; Foa, L.; Focardi, E.; Giazotto, A.; Giorgi, M.A.; Marrocchesi, P.S.; Menzione, A.; Ristori, L.; Rolandi, L.; Scribano, A.; Stefanini, A.; Vincelli, M.L.

    1981-01-01

    Detectors with very high space resolution have been built in the laboratory and tested at CERN in order to investigate their possible use in high energy physics experiments. These detectors consist of thin layers of silicon crystals acting as ionization chambers. Thin electrodes, structured in strips or in more fancy shapes are applied to their surfaces by metal coating. The space resolution which could be reached is of the order of a few microns. An interesting feature of these solid state detectors is that they can work under very high or low external pressure or at very low temperature. The use of these detectors would strongly reduce the dimensions and the cost of high energy experiments. (Auth.)

  5. Semiconductor Thermal Neutron Detector

    Directory of Open Access Journals (Sweden)

    Toru Aoki

    2014-02-01

    Full Text Available The  CdTe  and  GaN  detector  with  a  Gd  converter  have  been developed  and  investigated  as  a  neutron  detector  for neutron  imaging.  The  fabricated  Gd/CdTe  detector  with  the  25  mm  thick  Gd  was  designed  on  the  basis  of  simulation results  of  thermal  neutron  detection  efficiency  and  spatial  resolution.  The  Gd/CdTe  detector  shows  the  detection  of neutron  capture  gamma  ray  emission  in  the  155Gd(n,  g156Gd,  157Gd(n,  g158Gd  and  113Cd(n,  g114Cd  reactions  and characteristic X-ray emissions due to conversion-electrons generated inside the Gd film. The observed efficient thermal neutron detection with the Gd/CdTe detector shows its promise in neutron radiography application. Moreover, a BGaN detector has also investigated to separate neutron signal from gamma-ray clearly. 

  6. CdTe reflection anisotropy line shape fitting

    International Nuclear Information System (INIS)

    Molina-Contreras, J.R.

    2010-01-01

    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 1 and E 1 + Δ 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.

  7. Growth and analysis of micro and nano CdTe arrays for solar cell applications

    Science.gov (United States)

    Aguirre, Brandon Adrian

    CdTe is an excellent material for infrared detectors and photovoltaic applications. The efficiency of CdTe/CdS solar cells has increased very rapidly in the last 3 years to ˜20% but is still below the maximum theoretical value of 30%. Although the short-circuit current density is close to its maximum of 30 mA/cm2, the open circuit voltage has potential to be increased further to over 1 Volt. The main limitation that prevents further increase in the open-circuit voltage and therefore efficiency is the high defect density in the CdTe absorber layer. Reducing the defect density will increase the open-circuit voltage above 1 V through an increase in the carrier lifetime and concentration to tau >10 ns and p > 10 16 cm-3, respectively. However, the large lattice mismatch (10%) between CdTe and CdS and the polycrystalline nature of the CdTe film are the fundamental reasons for the high defect density and pose a difficult challenge to solve. In this work, a method to physically and electrically isolate the different kinds of defects at the nanoscale and understand their effect on the electrical performance of CdTe is presented. A SiO2 template with arrays of window openings was deposited between the CdTe and CdS to achieve selective-area growth of the CdTe via close-space sublimation. The diameter of the window openings was varied from the micro to the nanoscale to study the effect of size on nucleation, grain growth, and defect density. The resulting structures enabled the possibility to electrically isolate and individually probe micrometer and nanoscale sized CdTe/CdS cells. Electron back-scattered diffraction was used to observe grain orientation and defects in the miniature cells. Scanning and transmission electron microscopy was used to study the morphology, grain boundaries, grain orientation, defect structure, and strain in the layers. Finally, conducting atomic force microscopy was used to study the current-voltage characteristics of the solar cells. An

  8. Tuning optical properties of water-soluble CdTe quantum dots for biological applications

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, Anne S.; Tavernaro, Isabella; Machka, Friederike [Justus-Liebig-University Giessen, Institute of Inorganic and Analytical Chemistry (Germany); Dakischew, Olga; Lips, Katrin S. [Justus-Liebig-University Giessen, Laboratory of Experimental Trauma Surgery (Germany); Wickleder, Mathias S., E-mail: mathias.wickleder@anorg.chemie.uni-giessen.de [Justus-Liebig-University Giessen, Institute of Inorganic and Analytical Chemistry (Germany)

    2017-02-15

    In this study, two different synthetic methods in aqueous solution are presented to tune the optical properties of CdTe and CdSe semiconductor nanoparticles. Additionally, the influence of different temperatures, pressures, precursor ratios, surface ligands, bases, and core components in the synthesis was investigated with regard to the particle sizes and optical properties. As a result, a red shift of the emission and absorption maxima with increasing reaction temperature (100 to 220°C), pressure (1 to 25 bar), and different ratios of core components of alloyed semiconductor nanoparticles could be observed without a change of the particle size. An increase in particle size from 2.5 to 5 nm was only achieved by variation of the mercaptocarboxylic acid ligands in combination with the reaction time and used base. To get a first hint on the cytotoxic effects and cell uptake of the synthesized quantum dots, in vitro tests mesenchymal stem cells (MSCs) were carried out.

  9. Measurement stand for diagnosis of semiconductor detectors based on IBM PC/XT computer (4-way spectrometric analysis of pulses)

    International Nuclear Information System (INIS)

    Gruszecki, M.

    1990-01-01

    The technical assumptions and partial realization of our technological stand for quality inspection of semiconductor detectors for ionizing radiation manufactured in the INP in Cracow are described. To increase the efficiency of the measurements simultaneous checking of 4 semiconductor chips or finished products is suggested. In order to justify this measurement technique a review of possible variants of the measurement apparatus is presented for the systems consisting of home made units. Comparative parameters for the component modules and for complete measuring systems are given. The construction and operation of data acquisition system based on IBM PC/XT are described. The system ensures simultaneous registration of pulses obtained from 4 detectors with maximal rate of up to 500 x 10 3 pulses/s. 42 refs., 6 figs., 3 tabs. (author)

  10. 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)

  11. Noise and optimum filtering in spectrometers with semiconductor detectors operating at elevated temperature

    International Nuclear Information System (INIS)

    Dabrowski, W.; Korbel, K.

    1983-01-01

    The importance of the excess noise in the semiconductor detectors operating at the elevated temperature is discussed. Under the assumption of a conventional CR-RC type filtration the variancy of the noise output is determined. The new term ''second noise-corner time constant'' was proposed. The expression for relative signal-to-noise ratio as the dependence on the noise as well as circuits time constants was derived. It was also presented in a graphical form. 12 refs., 6 figs. (author)

  12. Design Strategies for High-Efficiency CdTe Solar Cells

    Science.gov (United States)

    Song, Tao

    With continuous technology advances over the past years, CdTe solar cells have surged to be a leading contributor in thin-film photovoltaic (PV) field. While empirical material and device optimization has led to considerable progress, further device optimization requires accurate device models that are able to provide an in-depth understanding of CdTe device physics. Consequently, this thesis is intended to develop a comprehensive model system for high-efficiency CdTe devices through applying basic design principles of solar cells with numerical modeling and comparing results with experimental CdTe devices. The CdTe absorber is central to cell performance. Numerical simulation has shown the feasibility of high energy-conversion efficiency, which requires both high carrier density and long minority carrier lifetime. As the minority carrier lifetime increases, the carrier recombination at the back surface becomes a limitation for cell performance with absorber thickness cell performance, since it can induce a large valence-band bending which suppresses the hole injection near the interface for the electron-hole recombination, but too large a spike is detrimental to photocurrent transport. In a heterojunction device with many defects at the emitter/absorber interface (high SIF), a thin and highly-doped emitter can induce strong absorber inversion and hence help maintain good cell performance. Performance losses from acceptor-type interface defects can be significant when interface defect states are located near mid-gap energies. In terms of specific emitter materials, the calculations suggest that the (Mg,Zn)O alloy with 20% Mg, or a similar type-I heterojunction partner with moderate DeltaE C (e.g., Cd(S,O) or (Cd,Mg)Te with appropriate oxygen or magnesium ratios) should yield higher voltages and would therefore be better candidates for the CdTe-cell emitter. The CdTe/substrate interface is also of great importance, particularly in the growth of epitaxial

  13. Linear and mass attenuation coefficient for CdTe compound of X-rays from 10 to 100 keV energy range in different phases

    Energy Technology Data Exchange (ETDEWEB)

    Saim, A., E-mail: saim1989asma@gmail.com; Tebboune, A.; Berkok, H.; Belameiri, N.; Belbachir, A.H.

    2014-07-25

    The Full Potential Linear Muffin Tin Orbitals method within the density functional theory has been utilized to calculate structural and electronic properties of the CdTe compound. We have checked that the CdTe has two phase-transitions from zinc-blend to cinnabar and from cinnabar to rocksalt. We have found that the rigidity, the energy and the nature of the gap change according to the phase change, so we can predict that a CdTe detector may have different behaviors in different phase conditions. In order to investigate this behavior change, the linear and the mass attenuation coefficients of X-ray in rocksalt, zinc-blend and cinnabar structures are calculated from 10 keV to100 keV, using the XCOM data. We have found that when CdTe undergoes a phase transition from zinc-blend to cinnabar, its linear attenuation coefficient decreases down to a value of about 100 times smaller than its initial one, and when it undergoes a transition from cinnabar to rocksalt it increases up to a value about 90 times larger than its initial one.

  14. DEPFET-detectors: New developments

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, G. [MPI Semiconductor Laboratory, Max Planck Institut fuer Physik, Otto Hahn Ring 6, D 81739 Munich (Germany)]. E-mail: gerhard.lutz@cern.ch; Andricek, L. [MPI Semiconductor Laboratory, Max Planck Institut fuer Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Eckardt, R. [MPI Semiconductor Laboratory, Max Planck Institut fuer extraterrestrische Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Haelker, O. [MPI Semiconductor Laboratory, Max Planck Institut fuer extraterrestrische Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Hermann, S. [MPI Semiconductor Laboratory, Max Planck Institut fuer extraterrestrische Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Lechner, P. [MPI Semiconductor Laboratory, PNSensor GmbH, Otto Hahn Ring 6, D 81739 Munich (Germany); Richter, R. [MPI Semiconductor Laboratory, Max Planck Institut fuer Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Schaller, G. [MPI Semiconductor Laboratory, Max Planck Institut fuer extraterrestrische Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Schopper, F. [MPI Semiconductor Laboratory, Max Planck Institut fuer extraterrestrische Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Soltau, H. [MPI Semiconductor Laboratory, PNSensor GmbH, Otto Hahn Ring 6, D 81739 Munich (Germany); Strueder, L. [MPI Semiconductor Laboratory, Max Planck Institut fuer extraterrestrische Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Treis, J. [MPI Semiconductor Laboratory, Max Planck Institut fuer extraterrestrische Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Woelfl, S. [MPI Semiconductor Laboratory, Max Planck Institut fuer extraterrestrische Physik, Otto Hahn Ring 6, D 81739 Munich (Germany); Zhang, C. [MPI Semiconductor Laboratory, Max Planck Institut fuer extraterrestrische Physik, Otto Hahn Ring 6, D 81739 Munich (Germany)

    2007-03-01

    The Depleted Field Effect Transistor (DEPFET) detector-amplifier structure forms the basis of a variety of detectors being developed at the MPI semiconductor laboratory. These detectors are foreseen to be used in astronomy and particle physics as well as other fields of science. The detector developments are described together with some intended applications. They comprise the X-ray astronomy missions XEUS and SIMBOL-X as well as the vertex detector of the planned International Linear Collider (ILC). All detectors are produced in the MPI semiconductor laboratory that has a complete silicon technology available.

  15. DEPFET-detectors: New developments

    International Nuclear Information System (INIS)

    Lutz, G.; Andricek, L.; Eckardt, R.; Haelker, O.; Hermann, S.; Lechner, P.; Richter, R.; Schaller, G.; Schopper, F.; Soltau, H.; Strueder, L.; Treis, J.; Woelfl, S.; Zhang, C.

    2007-01-01

    The Depleted Field Effect Transistor (DEPFET) detector-amplifier structure forms the basis of a variety of detectors being developed at the MPI semiconductor laboratory. These detectors are foreseen to be used in astronomy and particle physics as well as other fields of science. The detector developments are described together with some intended applications. They comprise the X-ray astronomy missions XEUS and SIMBOL-X as well as the vertex detector of the planned International Linear Collider (ILC). All detectors are produced in the MPI semiconductor laboratory that has a complete silicon technology available

  16. A Gamma Scanner Using a Ge(Li) Semi-Conductor Detector, with the Possibility of Operation in the Anti-Coincidence Mode

    Energy Technology Data Exchange (ETDEWEB)

    Forsyth, R S; Blackadder, W H

    1970-04-15

    A fuel element transport flask has been modified as a facility for gamma scanning irradiated fuel elements up to a length of 75 cm. By means of a Ge(Li) semi-conductor detector, satisfactory activity profiles along the specimens have been obtained, permitting the location of individual fuel pellets. An annular plastic detector surrounding the Ge(Li) detector allows operation of the spectrometer in the anti-coincidence mode, and reduction of the Compton continuum by about 50% has been obtained.

  17. A Gamma Scanner Using a Ge(Li) Semi-Conductor Detector, with the Possibility of Operation in the Anti-Coincidence Mode

    International Nuclear Information System (INIS)

    Forsyth, R.S.; Blackadder, W.H.

    1970-04-01

    A fuel element transport flask has been modified as a facility for gamma scanning irradiated fuel elements up to a length of 75 cm. By means of a Ge(Li) semi-conductor detector, satisfactory activity profiles along the specimens have been obtained, permitting the location of individual fuel pellets. An annular plastic detector surrounding the Ge(Li) detector allows operation of the spectrometer in the anti-coincidence mode, and reduction of the Compton continuum by about 50% has been obtained

  18. High Flux Energy-Resolved Photon-Counting X-Ray Imaging Arrays with CdTe and CdZnTe for Clinical CT

    International Nuclear Information System (INIS)

    Barber, William C.; Hartsough, Neal E.; Gandhi, Thulasidharan; Iwanczyk, Jan S.; Wessel, Jan C.; Nygard, Einar; Malakhov, Nail; Wawrzyniak, Gregor; Dorholt, Ole; Danielsen, Roar

    2013-06-01

    We have fabricated fast room-temperature energy dispersive photon counting x-ray imaging arrays using pixellated cadmium zinc (CdTe) and cadmium zinc telluride (CdZnTe) semiconductors. We have also fabricated fast application specific integrated circuits (ASICs) with a two dimensional (2D) array of inputs for readout from the CdZnTe sensors. The new CdTe and CdZnTe sensors have a 2D array of pixels with a 0.5 mm pitch and can be tiled in 2D. The new 2D ASICs have four energy discriminators per pixel with a linear energy response across the entire dynamic range for clinical CT. The ASICs can also be tiled in 2D and are designed to fit within the active area of the 2D sensors. We have measured several important performance parameters including; an output count rate (OCR) in excess of 20 million counts per second per square mm, an energy resolution of 7 keV full width at half maximum (FWHM) across the entire dynamic range, and a noise floor less than 20 keV. This is achieved by directly interconnecting the ASIC inputs to the pixels of the CdTE and CdZnTe sensors incurring very little additional capacitance. We present a comparison of the performance of the CdTe and CdZnTe sensors including the OCR, FWHM energy resolution, and noise floor. (authors)

  19. The importance of the time scale in radiation detection exemplified by comparing conventional and avalache semiconductor detectors

    Energy Technology Data Exchange (ETDEWEB)

    Tove, P A; Cho, Z H; Huth, G C [California Univ., Los Angeles (USA). Lab. of Nuclear Medicine and Radiation Biology

    1976-02-01

    The profound importance of the time scale of a radiation detection process is discussed in an analysis of limitations in energy resolution and timing, with emphasis on semiconductor detectors used for X-ray detection. The basic event detection time involves stopping of the particle and creating a distribution of free electrons and holes containing all desired information (energy, time position) about the particle or quantum, in a time approximately equal to 10/sup -12/s. The process of extracting this information usually involves a much longer time because the signal is generated in the relatively slow process of charge collection, and further prolongation may be caused by signal processing required to depress noise for improving energy resolution. This is a common situation for conventional semiconductor detectors with external amplifiers where time constants of 10/sup -5/-10/sup -4/s may be optimum, primarily because of amplifier noise. A different situation applies to the avalanche detector where internal amplification helps in suppressing noise without expanding the time scale of detections, resulting in an optimum time of 10/sup -9/-10/sup -8/s. These two cases are illustrated by plotting energy resolution vs. time constant, for different magnitudes of the parallel and series type noise sources. The effects of the inherent energy spread due to statistips and spatial inhomogeneities are also discussed to illustrate the potential of these two approaches for energy and time determination. Two constructional approaches for avalanche detectors are briefly compared.

  20. Photon counting and energy discriminating X-ray detectors. Benefits and applications

    International Nuclear Information System (INIS)

    Walter, David; Zscherpel, Uwe; Ewert, Uwe

    2016-01-01

    Since a few years the direct detection of X-ray photons into electrical signals is possible by usage of highly absorbing photo conducting materials (e.g. CdTe) as detection layer of an underlying CMOS semiconductor X-ray detector. Even NDT energies up to 400 keV are possible today, as well. The image sharpness and absorption efficiency is improved by the replacement of the unsharp scintillation layer (as used at indirect detecting detectors) by a photo conducting layer of much higher thickness. If the read-out speed is high enough (ca. 50 - 100 ns dead time) single X-ray photons can be counted and their energy measured. Read-out noise and dark image correction can be avoided. By setting energy thresholds selected energy ranges of the X-ray spectrum can be detected or suppressed. This allows material discrimination by dual-energy techniques or the reduction of image contributions of scattered radiation, which results in an enhanced contrast sensitivity. To use these advantages in an effective way, a special calibration procedure has to be developed, which considers also time dependent processes in the detection layer. This contribution presents some of these new properties of direct detecting digital detector arrays (DDAs) and shows first results on testing fiber reinforced composites as well as first approaches to dual energy imaging.

  1. Interaction of Water-Soluble CdTe Quantum Dots with Bovine Serum Albumin

    Science.gov (United States)

    2011-01-01

    Semiconductor nanoparticles (quantum dots) are promising fluorescent markers, but it is very little known about interaction of quantum dots with biological molecules. In this study, interaction of CdTe quantum dots coated with thioglycolic acid (TGA) with bovine serum albumin was investigated. Steady state spectroscopy, atomic force microscopy, electron microscopy and dynamic light scattering methods were used. It was explored how bovine serum albumin affects stability and spectral properties of quantum dots in aqueous media. CdTe–TGA quantum dots in aqueous solution appeared to be not stable and precipitated. Interaction with bovine serum albumin significantly enhanced stability and photoluminescence quantum yield of quantum dots and prevented quantum dots from aggregating. PMID:27502633

  2. Analysis and modelling of the performance of a new solid-state detector in nuclear medicine: from Anger- to Semiconductor-detectors

    International Nuclear Information System (INIS)

    Imbert, L.

    2012-01-01

    Myocardial single-photon emission computed tomography (SPECT) is considered as the gold standard for the diagnosis of coronary artery disease. Developed in the 1980's with rotating Anger gamma cameras, this technique could be dramatically enhanced by new imaging systems working with semiconductor detectors and which performances are clearly enhanced. Two semiconductor cameras, dedicated to nuclear cardiology and equipped with Cadmium Zinc Telluride detectors, have been recently commercialized: the Discovery NM- 530c (General Electric) and the DSPECT (Spectrum Dynamics). The performances of these CZT cameras were compared: 1) by a comprehensive analysis of phantom and human SPECT images considered as normal and 2) with the parameters commonly recommended for SPECT recording and reconstruction. The results show the superiority of the CZT cameras in terms of detection sensitivity, spatial resolution and contrast-to-noise ratio, compared to conventional Anger cameras. These properties might lead to dramatically reduce acquisition times and/or the injected activities. However, the limits of these new CZT cameras, as well as the mechanism of certain artefacts, remain poorly known. This knowledge could be enhanced by a numerical modeling of the DSPECT camera, and this might also help to optimize acquisition and reconstruction parameters. We developed a simulator where the geometry of the detectors of the DSPECT camera and their energy response were modeled in the GATE platform. In order to validate this simulator, actually recorded data were compared with simulated data through three performance parameters: detection sensitivity, spatial resolution and energy resolution. Results were in agreement between simulated and actually recorded data. This observation validates the DSPECT simulator and opens the door to further studies planed to optimize the recorded and reconstruction processes, especially for complex protocols such as simultaneous dual-radionuclide acquisition

  3. The effects of intense gamma-irradiation on the alpha-particle response of silicon carbide semiconductor radiation detectors

    International Nuclear Information System (INIS)

    Ruddy, Frank H.; Seidel, John G.

    2007-01-01

    Silicon Carbide (SiC) semiconductor radiation detectors are being developed for alpha-particle, X-ray and Gamma-ray, and fast-neutron energy spectrometry. SiC detectors have been operated at temperatures up to 306 deg. C and have also been found to be highly resistant to the radiation effects of fast-neutron and charged-particle bombardments. In the present work, the alpha-particle response of a SiC detector based on a Schottky diode design has been carefully monitored as a function of 137 Cs gamma-ray exposure. The changes in response have been found to be negligible for gamma exposures up to and including 5.4 MGy, and irradiations to higher doses are in progress

  4. Fractal features of CdTe thin films grown by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hosseinpanahi, Fayegh, E-mail: f.hosseinpanahi@yahoo.com [Department of Physics, Payame Noor University, P.O. Box 19395-4697, Tehran (Iran, Islamic Republic of); Raoufi, Davood [Department of Physics, University of Bu Ali Sina, P.O. Box 65174, Hamedan (Iran, Islamic Republic of); Ranjbarghanei, Khadijeh [Department of Physics, Plasma Physics Research Center, Science & Research Branch Islamic Azad University, Tehran (Iran, Islamic Republic of); Karimi, Bayan [Department of Physics, Payame Noor University, P.O. Box 19395-4697, Tehran (Iran, Islamic Republic of); Babaei, Reza [Department of Physics, Plasma Physics Research Center, Science & Research Branch Islamic Azad University, Tehran (Iran, Islamic Republic of); Hasani, Ebrahim [Department of Physics, University of Bu Ali Sina, P.O. Box 65174, Hamedan (Iran, Islamic Republic of)

    2015-12-01

    Graphical abstract: - Highlights: • CdTe thin films were deposited on glass substrates by RF magnetron sputtering at room temperature with different deposition time 5, 10 and 15 min. • Nanostructure of CdTe layer indicates that CdTe films are polycrystalline and have zinc blende structure, irrespective of their deposition time. • Complexity and roughness of the CdTe films and strength of multifractality increase with increasing deposition time. • Detrended fluctuation analysis (DFA) and also multifractal detrended fluctuation analysis (MFDFA) methods showed that prepared CdTe films have multifractal nature. - Abstract: 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. Fractal features of CdTe thin films grown by RF magnetron sputtering

    International Nuclear Information System (INIS)

    Hosseinpanahi, Fayegh; Raoufi, Davood; Ranjbarghanei, Khadijeh; Karimi, Bayan; Babaei, Reza; Hasani, Ebrahim

    2015-01-01

    Graphical abstract: - Highlights: • CdTe thin films were deposited on glass substrates by RF magnetron sputtering at room temperature with different deposition time 5, 10 and 15 min. • Nanostructure of CdTe layer indicates that CdTe films are polycrystalline and have zinc blende structure, irrespective of their deposition time. • Complexity and roughness of the CdTe films and strength of multifractality increase with increasing deposition time. • Detrended fluctuation analysis (DFA) and also multifractal detrended fluctuation analysis (MFDFA) methods showed that prepared CdTe films have multifractal nature. - Abstract: 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.

  6. Simulation of drift dynamics of arbitrary carrier distributions in complex semiconductor detectors

    CERN Document Server

    De Castro Manzano, Pablo

    2014-01-01

    An extensible open-source C++ software for the simulation of elec- trons and holes drift in semiconductor detectors of complex geometries has been developed in order to understand transient currents and charge collection efficiencies of arbitrary charge distributions. The simulation is based on Ramo’s theorem formalism to obtain induced currents in the electrodes. Efficient open source C++ numerical libraries are used to ob- tain the electric and weighting field using finite-element methods and to simulate the carrier transport. A graphical user interface is also provided. The tool has already been proved useful to model laser induced transient currents

  7. Contacts to semiconductors

    International Nuclear Information System (INIS)

    Tove, P.A.

    1975-08-01

    Contacts to semiconductors play an important role in most semiconductor devices. These devices range from microelectronics to power components, from high-sensitivity light or radiation detectors to light-emitting of microwave-generating components. Silicon is the dominating material but compound semiconductors are increasing in importance. The following survey is an attempt to classify contact properties and the physical mechanisms involved, as well as fabrication methods and methods of investigation. The main interest is in metal-semiconductor type contacts where a few basic concepts are dealt with in some detail. (Auth.)

  8. 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

  9. Development and characterization of the lead iodide semiconductor detector

    International Nuclear Information System (INIS)

    Oliveira, Icimone Braga de

    2001-01-01

    A methodology for purification and growth of PbI 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 ( 241 Am) alpha particle and ( 241 Am, 57 Co, 133 Ba and 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 241 Am alpha particle and the gamma rays resolution was compatible with the literature. The photosensibility of the PbI 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)

  10. 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.

  11. X-Ray Diffraction (XRD) Characterization Methods for Sigma=3 Twin Defects in Cubic Semiconductor (100) Wafers

    Science.gov (United States)

    Park, Yeonjoon (Inventor); Kim, Hyun Jung (Inventor); Skuza, Jonathan R. (Inventor); Lee, Kunik (Inventor); King, Glen C. (Inventor); Choi, Sang Hyouk (Inventor)

    2017-01-01

    An X-ray defraction (XRD) characterization method for sigma=3 twin defects in cubic semiconductor (100) wafers includes a concentration measurement method and a wafer mapping method for any cubic tetrahedral semiconductor wafers including GaAs (100) wafers and Si (100) wafers. The methods use the cubic semiconductor's (004) pole figure in order to detect sigma=3/{111} twin defects. The XRD methods are applicable to any (100) wafers of tetrahedral cubic semiconductors in the diamond structure (Si, Ge, C) and cubic zinc-blend structure (InP, InGaAs, CdTe, ZnSe, and so on) with various growth methods such as Liquid Encapsulated Czochralski (LEC) growth, Molecular Beam Epitaxy (MBE), Organometallic Vapor Phase Epitaxy (OMVPE), Czochralski growth and Metal Organic Chemical Vapor Deposition (MOCVD) growth.

  12. Recent results from a Si/CdTe semiconductor Compton telescope

    International Nuclear Information System (INIS)

    Tanaka, Takaaki; Watanabe, Shin; Takeda, Shin'ichiro; Oonuki, Kousuke; Mitani, Takefumi; Nakazawa, Kazuhiro; Takashima, Takeshi; Takahashi, Tadayuki; Tajima, Hiroyasu; Sawamoto, Naoyuki; Fukazawa, Yasushi; Nomachi, Masaharu

    2006-01-01

    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 (DSSDs) 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 o (FWHM) at 511keV, and the energy resolution is 14keV (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 137 Cs source, we successfully obtained an image and a spectrum of 662keV line emission with this method. As a next step, development of larger DSSDs with a size of 4cmx4cm is under way 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

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

    CERN Document Server

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

    2015-01-01

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

  14. Characterization and photoluminescence studies of CdTe ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The major objective of this work was to detect the change of photoluminescence (PL) intensity of. CdTe nanoparticles (NPs) before and after transfer from liquid phase to polystyrene (PS) matrix by electro- spinning technique. Thio-stabilized CdTe NPs were first synthesized in aqueous, then enwrapped by cetyl-.

  15. Detector materials: germanium and silicon

    International Nuclear Information System (INIS)

    Haller, E.E.

    1981-11-01

    This article is a summary of a short course lecture given in conjunction with the 1981 Nuclear Science Symposium. The basic physical properties of elemental semiconductors are reviewed. The interaction of energetic radiation with matter is discussed in order to develop a feeling for the appropriate semiconductor detector dimensions. The extremely low net dopant concentrations which are required are derived directly from the detector dimensions. A survey of the more recent techniques which have been developed for the analysis of detector grade semiconductor single crystals is presented

  16. 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

  17. Optical properties of hybrid semiconductor-metal structures

    Energy Technology Data Exchange (ETDEWEB)

    Kreilkamp, L.E.; Pohl, M.; Akimov, I.A.; Yakovlev, D.R.; Bayer, M. [Experimentelle Physik 2, Technische Universitaet Dortmund, 44221 Dortmund (Germany); Belotelov, V.I.; Zvezdin, A.K. [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, 119992 Moscow (Russian Federation); Karczewski, G.; Wojtowicz, T. [Institute of Physics, Polish Academy of Sciences, 02668 Warsaw (Poland); Rudzinski, A.; Kahl, M. [Raith GmbH, Konrad-Adenauer-Allee 8, 44263 Dortmund (Germany)

    2012-07-01

    We study the optical properties of hybrid nanostructures comprising a semiconductor CdTe quantum well (QW) separated by a thin CdMgTe cap layer of 40 nm from a patterned gold film. The CdTe/CdMgTe QW structure with a well width of 10nm was grown by molecular beam epitaxy. The one-dimensional periodic gold films on top were made using e-beam lithography and lift-off process. The investigated structures can be considered as plasmonic crystals because the metal films attached to the semiconductor are patterned with a period in the range from 475 to 600 nm, which is comparable to the surface plasmon-polariton (SPP) wavelength. Angle dependent reflection spectra at room temperature clearly show plasmonic resonances. PL spectra taken at low temperatures of about 10 K under below- and above-barrier illumination show significant modifications compared to the unstructured QW sample. The number of emission lines and their position shift change depending on the excitation energy. The role of exciton-SPP coupling and Schottky barrier at the semiconductor-metal interface are discussed.

  18. Heart imaging by cadmium telluride gamma camera European Program 'BIOMED' consortium

    CERN Document Server

    Scheiber, C; Chambron, J; Prat, V; Kazandjan, A; Jahnke, A; Matz, R; Thomas, S; Warren, S; Hage-Hali, M; Regal, R; Siffert, P; Karman, M

    1999-01-01

    Cadmium telluride semiconductor detectors (CdTe) operating at room temperature are attractive for medical imaging because of their good energy resolution providing excellent spatial and contrast resolution. The compactness of the detection system allows the building of small light camera heads which can be used for bedside imaging. A mobile pixellated gamma camera based on 2304 CdTe (pixel size: 3x3 mm, field of view: 15 cmx15 cm) has been designed for cardiac imaging. A dedicated 16-channel integrated circuit has also been designed. The acquisition hardware is fully programmable (DSP card, personal computer-based system). Analytical calculations have shown that a commercial parallel hole collimator will fit the efficiency/resolution requirements for cardiac applications. Monte-Carlo simulations predict that the Moire effect can be reduced by a 15 deg. tilt of the collimator with respect to the detector grid. A 16x16 CdTe module has been built for the preliminary physical tests. The energy resolution was 6.16...

  19. Enhancement effect of CdTe quantum dots-IgG bioconjugates on chemiluminescence of luminol-H2O2 system

    International Nuclear Information System (INIS)

    Kanwal, Shamsa; Traore, Zoumana; Zhao Chunfang; Su Xingguang

    2010-01-01

    In this paper we developed an entirely new and highly sensitive luminol-H 2 O 2 flow injection chemiluminescence system using the enhancement effect of CdTe quantum dots-IgG bioconjugates. Immunoglobulin G (IgG) as a kind of bio-molecule was conjugated to different sized CdTe semiconductor quantum dots (QDs). Using PL spectra and CL intensity profiles, it was found that chemiluminescence resonance energy transfer (CRET) was possibly occurring between CdTe-IgG bioconjugate and luminol. Under optimum conditions, increase of IgG concentration in CdTe-IgG bioconjugate resulted enhancing effect on CL intensity of luminol-H 2 O 2 system. Moreover quenching effects on CL intensity by addition of different proteases can construct turn off biosensor for these proteases with low detection limits and wide linear range. Furthermore, the effects of various organic and inorganic species on CdTe-IgG bioconjugates enhanced luminol-H 2 O 2 CL system were also studied in this paper.

  20. General specifications for silicon semiconductors for use in radiation dosimetry

    International Nuclear Information System (INIS)

    Rikner, G.; Grusell, E.

    1987-01-01

    Silicon semiconductor detectors used in radiation dosimetry have different properties, just as e.g. ionisation chambers, affecting the interaction of radiation with matter in the vicinity of the sensitive volume of the detector, e.g. wall materials, and also the collection of the charges liberated in the detector by the radiation. The charge collection depends on impurities, lattice imperfections and other properties of the semiconductor crystal. In this paper the relevant parameters of a silicon semiconductor detector intended for dosimetry are reviewed. The influence of doping material, doping level, various effects of radiation damage, mechanical construction, detector size, statistical noise and connection to the electrometer are discussed. (author)

  1. Electrical limitations to energy resolution in semiconductor particle detectors; Limitations electriques du pouvoir de resolution en energie des detecteurs a semi-conducteurs; Ehlektricheskie ogranicheniya razreshayushchej sposobnosti po ehnergii v poluprovodnikovykh detektorakh chastits; Limitaciones electricas en la resolucion energetica de detectores de particulas a base de semiconductores

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, W L; Goulding, F S [Lawrence Radiation Laboratory, University of California, Berkeley, CA (United States)

    1962-04-15

    Based on the assumption that the noise contribution of a semiconductor detector is due solely to its bulk properties, equations are presented which indicate the theoretical limits of noise in detectoramplifier combinations. These equations show that an optimum amplifier time-constant and detector bias voltage exist for which condition the minimum noise is independent of the semiconductor resistivity. The optimum performance of a detector-amplifier system is shown to depend only upon detector area, input capacity (less detector capacity), semiconductor minority carrier lifetime and the transconductance of the amplifier input tube. A new detector structure which includes a guard-ring electrode as an integral part of the detector structure is described which has the effect of largely eliminating noise due to surface leakage. Experimental results for detector leakage and energy resolution which agree well with theory are presented. The theoretical limit of noise, expressed as full width at half maximum, is from 7 to 10 keV for 1-cm{sup 2} p-type silicon detectors at 25{sup o}C. (author) [French] Partant de l'hypothese que le bruit imputable au detecteur a semi-conducteur est du exclusivement aux proprietes fondamentales du semi-conducteur, les auteurs etablissent des equations donnant les limites theoriques du bruit dans les combinaisons detecteur-amplificateur. Ces equations montrent qu'il existe une constante de temps optimum de l'amplificateur et une tension de polarisation du detecteur, pour lesquelles le bruit minimum est independant de la resistivite du semi-conducteur. Les auteurs prouvent que l'optimum de fonctionnement d'un ensemble detecteur-amplificateur ne depend que de la surface du detecteur, de la capacite a l'entree (deduction faite de la capacite du detecteur), du porteur minoritaire du semi-conducteur, de la duree de vie et de la transconductance du tube d'entree de l'amplificateur. Ils decrivent un modele nouveau de detecteur qui comprend une

  2. Spectral correction algorithm for multispectral CdTe x-ray detectors

    DEFF Research Database (Denmark)

    Christensen, Erik D.; Kehres, Jan; Gu, Yun

    2017-01-01

    Compared to the dual energy scintillator detectors widely used today, pixelated multispectral X-ray detectors show the potential to improve material identification in various radiography and tomography applications used for industrial and security purposes. However, detector effects, such as charge...

  3. 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 μ m mixed-signal CMOS technology and characterized with an external test pulse. The power consumption of these parts is 200 μ W 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.

  4. 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).

  5. Development of a two-dimensional ASIC for hard X-ray spectroscopy and imaging with a CdTe pixel detector

    International Nuclear Information System (INIS)

    Hiruta, Tatsuro; Tamura, K.; Ikeda, H.; Nakazawa, K.; Takasima, T.; Takahashi, T.

    2006-01-01

    We are developing a two-dimensional analog ASIC for the readout of pixel sensors based on silicon (Si) or cadmium telluride (CdTe) for spectroscopic imaging observations in the X-ray and gamma-ray regions. The aim for the ASIC is to obtain a low-noise performance better than 100 electrons (rms) with self-triggering capabilities. As the first step of prototyping, we have fabricated several ASICs. We obtained an energy resolution of 5.4 keV (FWHM) for 81 keV gamma-rays from 133 Ba with a one-dimensional ASIC connected to a CdTe diode and also verified a readout architecture via a two-dimensional ASIC with 144 pixel channels. Based on the results obtained and experience gained through prototype ASICs, we are developing a 4096-channel two-dimensional analog ASIC

  6. Interaction of porphyrins with CdTe quantum dots

    International Nuclear Information System (INIS)

    Zhang Xing; Liu Zhongxin; Ma Lun; Hossu, Marius; Chen Wei

    2011-01-01

    Porphyrins may be used as photosensitizers for photodynamic therapy, photocatalysts for organic pollutant dissociation, agents for medical imaging and diagnostics, applications in luminescence and electronics. The detection of porphyrins is significantly important and here the interaction of protoporphyrin-IX (PPIX) with CdTe quantum dots was studied. It was observed that the luminescence of CdTe quantum dots was quenched dramatically in the presence of PPIX. When CdTe quantum dots were embedded into silica layers, almost no quenching by PPIX was observed. This indicates that PPIX may interact and alter CdTe quantum dots and thus quench their luminescence. The oxidation of the stabilizers such as thioglycolic acid (TGA) as well as the nanoparticles by the singlet oxygen generated from PPIX is most likely responsible for the luminescence quenching. The quenching of quantum dot luminescence by porphyrins may provide a new method for photosensitizer detection.

  7. 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...

  8. The effect of excitons on CdTe solar cells

    International Nuclear Information System (INIS)

    Karazhanov, S. Zh.; Zhang, Y.; Mascarenhas, A.; Deb, S.

    2000-01-01

    Temperature and doping-level dependence of CdTe solar cells is investigated, taking into account the involvement of excitons on photocurrent transport. We show that the density of excitons in CdTe is comparable with that of minority carriers at doping levels ≥10 15 cm -3 . From the investigation of the dark-saturation current, we show that the product of electron and hole concentrations at equilibrium is several orders of magnitude more than the square of the intrinsic carrier concentration. With this assumption, we have studied the effect of excitons on CdTe solar cells, and the effect is negative. CdTe solar cell performance with excitons included agrees well with existing experimental results. (c) 2000 American Institute of Physics

  9. Photostimulated changes of properties of CdTe films

    Energy Technology Data Exchange (ETDEWEB)

    Dzhafarov, T.D. [Institute of Physics, Azerbaijan National Academy of Sciences, AZ-1143 Baku (Azerbaijan); Yesilkaya, S.S. [Department of Physics, Yildiz Technical University, 34210 Esenler/Istanbul (Turkey)

    2007-08-15

    The effect of illumination during the close-spaced sublimation (CSS) growth on composition, structural, electrical, optical and photovoltaic properties of CdTe films and CdTe/CdS solar cells were investigated. Data on comparative study by using X-ray diffraction (XRD), scanning electron microscopy (SEM), absorption spectra and conductivity-temperature measurements of CdTe films prepared by CSS method in dark (CSSD) and under illumination (CSSI) were presented. It is shown that the growth rate and the grain size of CdTe films grown under illumination is higher (by factor about of 1.5 and 3 respectively) than those for films prepared without illumination. The energy band gap of CdTe films fabricated by both technology, determined from absorption spectra, is same (about of 1.50 eV), however conductivity of the CdTe films produced by CSSI is considerably greater (by factor of 10{sup 7}) than that of films prepared by CSSD. The photovoltaic parameters of pCdTe/nCdS solar cells fabricated by photostimulated CSSI technology (J{sub sc}=28 mA/cm{sup 2}, V{sub oc}=0.63 V) are considerably larger than those for cells prepared by CSSD method (J{sub sc}=22 mA/cm{sup 2}, V{sub oc}=0.52 V). A mechanism of photostimulated changes of properties of CdTe films and improvement of photovoltaic parameters of CdTe/CdS solar cells is suggested. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. 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.

  11. Detector trends

    International Nuclear Information System (INIS)

    Charpak, G.

    1986-01-01

    The author describes briefly the development of detectors for high energy physics experiments. Especially considered are semiconductor microstrip detectors, drift tubes, holographic bubble chambers, scintillating fiber optics, and calorimeters. (HSI).

  12. PC based analysis of gamma ray spectra generated by semiconductor detectors

    International Nuclear Information System (INIS)

    Abani, M.C.; Madan, V.K.

    1993-01-01

    This report describes a spectrum analysis method and computer program for analysis of gamma spectra obtained by using semiconductor detectors and multichannel analysers. The analysis steps incorporated are smoothing, peak location using signal processing method of convolution, selectable background subtraction viz linear, polynomial and step like, peak fitting both for singlets and doublets using Mukoyama's method for evaluation of full width at half maximum and area evaluation including errors in its evaluation. The program also provides a facility for energy calibration. Typical results of analysis for singlets and doublets are included. This report is based on Wilson's report which has been modified and extended. The program is written in BASIC and its listing is included in the appendices. (author). 20 refs., 2 figs., 2 tabs

  13. 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)

  14. 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)

  15. On the doping problem of CdTe films: The bismuth case

    Energy Technology Data Exchange (ETDEWEB)

    Vigil-Galan, O. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico); Brown, M. [Department of Physics and Astronomy, The University of Toledo, 43606 Toledo, OH (United States); Ruiz, C.M. [Depto. Fisica de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Vidal-Borbolla, M.A. [Instituto de Investigacion en Comunicacion Optica, Av. Karakorum 1470, Lomas 4a. Secc., 78210 San Luis Potosi, SLP (Mexico); Ramirez-Bon, R. [CINVESTAV-IPN, U. Queretaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, 76230 Santiago de Queretaro, Qro. (Mexico); Sanchez-Meza, E. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico); Tufino-Velazquez, M. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico)], E-mail: mtufinovel@yahoo.com.mx; Calixto, M. Estela [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico); Compaan, A.D. [Department of Physics and Astronomy, The University of Toledo, 43606 Toledo, OH (United States); Contreras-Puente, G. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico)

    2008-08-30

    The controlled increase of hole concentration is an important issue and still an unsolved problem for polycrystalline CdTe-based solar cells. The typical hole concentration of as-grown CdTe thin-films goes up to 10{sup 13} cm{sup -3}, depending on the specific growth technique. The highest electron concentration obtained for CdS, the suitable window partner material of CdTe, is around 10{sup 15} cm{sup -3}. Thus, the PV-performance of a CdS/CdTe device can be optimized if the hole concentration in CdTe is increased. We have faced up this problem by studying the electrical properties of two types of CdTe films: CdTe films grown by Close Space Vapor Transport using a CdTe:Bi powder as the starting material and CdTe sputtered films doped by implantation with different Bi-doses. Temperature-dependent resistivity and Hall effect measurements and a discussion on the efficiency of both doping processes are presented.

  16. On the doping problem of CdTe films: The bismuth case

    International Nuclear Information System (INIS)

    Vigil-Galan, O.; Brown, M.; Ruiz, C.M.; Vidal-Borbolla, M.A.; Ramirez-Bon, R.; Sanchez-Meza, E.; Tufino-Velazquez, M.; Calixto, M. Estela; Compaan, A.D.; Contreras-Puente, G.

    2008-01-01

    The controlled increase of hole concentration is an important issue and still an unsolved problem for polycrystalline CdTe-based solar cells. The typical hole concentration of as-grown CdTe thin-films goes up to 10 13 cm -3 , depending on the specific growth technique. The highest electron concentration obtained for CdS, the suitable window partner material of CdTe, is around 10 15 cm -3 . Thus, the PV-performance of a CdS/CdTe device can be optimized if the hole concentration in CdTe is increased. We have faced up this problem by studying the electrical properties of two types of CdTe films: CdTe films grown by Close Space Vapor Transport using a CdTe:Bi powder as the starting material and CdTe sputtered films doped by implantation with different Bi-doses. Temperature-dependent resistivity and Hall effect measurements and a discussion on the efficiency of both doping processes are presented

  17. The basics of experimental determination of the Fano factor in intrinsic semiconductors

    International Nuclear Information System (INIS)

    Samedov, Victor-V.

    2013-06-01

    Intrinsic semiconductors such as High Purity Germanium Detectors are exceptional X-ray and gamma-ray detectors because of their large sizes and small band gap. They are used for fundamental scientific researches, nuclear material safeguards and security, environmental protection, and human health and safety. The fundamental limit of the energy resolution of a semiconductor detector is determined by variance in the number of electron-hole pairs produced by X-rays in detector volume. The principal characteristic of material for using as semiconductor detector is the Fano factor that determines the fluctuation in the number of electron-hole pairs. Now, all existing methods of experimental determination of the Fano factor in semiconductors are based on the subtraction of electronic noise from the signal variance. In this work, I propose the method of experimental determination of the Fano factor in a planar semiconductor detector based on dependences of the mean amplitude and the energy resolution on the electric field. It was shown that inverse electric field expansion of these dependences allow determining the Fano factor, electron mobility lifetime product, and relative variance of electron lifetime due to inhomogeneous charge transport in semiconductor material. The important advantage of the proposed method is independence on detector electronic noise. (authors)

  18. 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.

  19. Processing of semiconductors and thin film solar cells using electroplating

    Science.gov (United States)

    Madugu, Mohammad Lamido

    The global need for a clean, sustainable and affordable source of energy has triggered extensive research especially in renewable energy sources. In this sector, photovoltaic has been identified as a cheapest, clean and reliable source of energy. It would be of interest to obtain photovoltaic material in thin film form by using simple and inexpensive semiconductor growth technique such as electroplating. Using this growth technique, four semiconductor materials were electroplated on glass/fluorine-doped tin oxide (FTO) substrate from aqueous electrolytes. These semiconductors are indium selenide (In[x]Sey), zinc sulphide (ZnS), cadmium sulphide (CdS) and cadmium telluride (CdTe). In[x]Se[y] and ZnS were incorporated as buffer layers while CdS and CdTe layers were utilised as window and absorber layers respectively. All materials were grown using two-electrode (2E) system except for CdTe which was grown using 3E and 2E systems for comparison. To fully optimise the growth conditions, the as-deposited and annealed layers from all the materials were characterised for their structural, morphological, optical, electrical and defects structures using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), optical absorption (UV-Vis spectroscopy), photoelectrochemical (PEC) cell measurements, current-voltage (I-V), capacitance-voltage (C-V), DC electrical measurements, ultraviolet photoelectron spectroscopy (UPS) and photoluminescence (PL) techniques. Results show that InxSey and ZnS layers were amorphous in nature and exhibit both n-type and p-type in electrical conduction. CdS layers are n-type in electrical conduction and show hexagonal and cubic phases in both the as-deposited and after annealing process. CdTe layers show cubic phase structure with both n-type and p-type in electrical conduction. CdTe-based solar cell structures with a n-n heterojunction plus large Schottky barrier, as well as multi-layer graded

  20. Semiconductor sensors

    International Nuclear Information System (INIS)

    Hartmann, Frank

    2011-01-01

    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.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

    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.

  2. Simulated Performances of a Very High Energy Tomograph for Non-Destructive Characterization of large objects

    Directory of Open Access Journals (Sweden)

    Kistler Marc

    2018-01-01

    The upgrade of the detection part needs a thorough study of the performance of two detectors: a series of CdTe semiconductor sensors and two arrays of segmented CdWO4 scintillators with different pixel sizes. This study consists in a Quantum Accounting Diagram (QAD analysis coupled with Monte-Carlo simulations. The scintillator arrays are able to detect millimeter details through 140 cm of concrete, but are limited to 120 cm for smaller ones. CdTe sensors have lower but more stable performance, with a 0.5 mm resolution for 90 cm of concrete. The choice of the detector then depends on the preferred characteristic: the spatial resolution or the use on large volumes. The combination of the features of the source and the studies on the detectors gives the expected performance of the whole equipment, in terms of signal-over-noise ratio (SNR, spatial resolution and acquisition time.

  3. Bromine doping of CdTe and CdMnTe epitaxial layers grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Waag, A. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Scholl, S. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Schierstedt, K. von (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Hommel, D. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstoff-Forschung, Stuttgart (Germany))

    1993-03-01

    We report on the n-type doping of CdTe and CdMnTe with bormine as a novel dopant material. /the thin films were grown by molecular beam epitaxy. ZnBr[sub 2] was used as a source material for the n-type doping. Free carrier concentrations at room temperature of up to 2.8x10[sup 18] cm[sup -3] could be readily obtained for both CdTe as well as CdMnTe thin films with Mn concentrations below 10%. This is to our knowledge the highest value ever obtained for the dilute magnetic semiconductor CdMnTe. For ZnBr[sub 2] source temperatures up to 60 C - corresponding to a free carrier concentration of (2-3)x10[sup 18] cm[sup -3] - the free carrier concentration of the epitaxial film increases with ZnBr[sub 2] source temperature. For higher ZnBr[sub 2] source temperatures compensation becomes dominant, which is indicated by a steep decrease of the free carrier concentration with increasing ZnBr[sub 2] source temperature. In addition the carrier mobility decreases drastically for such high dopant fluxes. A model of bromine incorporation is proposed. (orig.)

  4. Amplifier channel for a fission fragment semiconductor detector

    International Nuclear Information System (INIS)

    Tyurin, G.P.

    1981-01-01

    To compensate the decrease of the transformation coefficient of fission fragment semiconductor detector (SCD) developed is a special amplification channel with controlled transfer coefficient. The block diagram of the channel is presented, the main functional units of which are as follows: preamplifying head with charge-sensitive and timing preamplifiers, linear amplifier and the circuit of spectrum position stabilization, which includes a differential discriminator, integrator and reference signal generator. The amplification channel is made in the CAMAC standard and has the following specifications: dinamical input capacitance of charge-sensitive amplifier c=10000 n PHI, signal amplitude at output of the linear amplifier at energy of fission fragments of 120 MeV has negative polarity and is equal to 5 V. Pulse amplitude change at SCD sensitivity decrease to 50% constitutes not more than 1%. Timing preamplifier has the gain factor at voltage of K=80 at front duration of 3.5 nc. Time resolution of the amplification channel is not worse than 1 nc. Dimensions of preamplifying head are 40x40x15 mm. The amplification channel permitted to use SCD for long-term measurements of fission fragment spectra [ru

  5. Calibration of the hard x-ray detectors for the FOXSI solar sounding rocket

    Science.gov (United States)

    Athiray, P. S.; Buitrago-Casas, Juan Camilo; Bergstedt, Kendra; Vievering, Juliana; Musset, Sophie; Ishikawa, Shin-nosuke; Glesener, Lindsay; Takahashi, Tadayuki; Watanabe, Shin; Courtade, Sasha; Christe, Steven; Krucker, Säm.; Goetz, Keith; Monson, Steven

    2017-08-01

    The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket experiment conducts direct imaging and spectral observation of the Sun in hard X-rays, in the energy range 4 to 20 keV. These high-sensitivity observations are used to study particle acceleration and coronal heating. FOXSI is designed with seven grazing incidence optics modules that focus X-rays onto seven focal plane detectors kept at a 2m distance. FOXSI-1 was flown with seven Double-sided Si Strip Detectors (DSSD), and two of them were replaced with CdTe detectors for FOXSI-2. The upcoming FOXSI-3 flight will carry DSSD and CdTe detectors with upgraded optics for enhanced sensitivity. The detectors are calibrated using various radioactive sources. The detector's spectral response matrix was constructed with diagonal elements using a Gaussian approximation with a spread (sigma) that accounts for the energy resolution of the detector. Spectroscopic studies of past FOXSI flight data suggest that the inclusion of lower energy X-rays could better constrain the spectral modeling to yield a more precise temperature estimation of the hot plasma. This motivates us to carry out an improved calibration to better understand the finer-order effects on the spectral response, especially at lower energies. Here we report our improved calibration of FOXSI detectors using experiments and Monte-Carlo simulations.

  6. Se-Se isoelectronic centers in high purity CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Najjar, Rita; Andre, Regis; Mariette, Henri [CEA-CNRS, Nanophysique et Semiconducteurs, Institut Neel, 25 rue des martyrs, 38042 Grenoble (France); Golnik, Andrzej; Kossacki, Piotr; Gaj, Jan A. [Institute of Experimental Physics, University of Warsaw, Hoza 69, 00-681 Warsaw (Poland)

    2010-06-15

    We evidence zero-dimensional exciton states trapped on isoelectronic Se centers in CdTe quantum wells, {delta}-doped with Se. Thanks to special precautions taken to have very high purity CdTe heterostructures, it is possible to observe, in photoluminescence spectra, sharp discrete lines arising from individual centers related to the Se doping. These emission lines appear at about 40 meV below the CdTe band gap energy. The most prominent lines are attributed to the recombination of excitons bound to nearest-neighbor selenium pairs in a tetrahedral CdTe environment. This assignment is confirmed by a common linear polarization direction of the emitted light, parallel to <110>. These excitons localized on individual isoelectronic traps are good candidates as single photon emitters (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Influence of EDTA2− on the hydrothermal synthesis of CdTe nanocrystallites

    International Nuclear Information System (INIS)

    Gong Haibo; Hao Xiaopeng; Wu Yongzhong; Cao Bingqiang; Xu Hongyan; Xu Xiangang

    2011-01-01

    Transformation from Te nanorods to CdTe nanoparticles was achieved with the assistance of EDTA as a ligand under hydrothermal conditions. Experimental results showed that at the beginning of reaction Te nucleated and grew into nanorods. With the proceeding of reaction, CdTe nucleus began to emerge on the surface, especially on the tips of Te nanorods. Finally, nearly monodispersed hexagonal CdTe nanoparticles with diameters of about 200 nm were obtained. The effects of EDTA on the morphology and formation of CdTe nanoparticles were discussed in consideration of the strong ligand-effect of EDTA, which greatly decreased the concentration of Cd 2+ . Furthermore, the possible formation process of CdTe nanoparticles from Te nanorods was further proposed. The crystal structure and morphology of the products were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). - Graphical Abstract: Firstly, Te nucleated and grew into nanorods in the presence of EDTA 2− . Then CdTe nucleus began to emerge on Te nanorods and finally monodispersed CdTe nanoparticles were obtained. Highlights: ► EDTA serves as a strong ligand with Cd 2+ . ► The existence of EDTA constrains the nucleation of CdTe and promotes the formation of Te nanorods. ► With the proceeding of reaction, CdTe nucleus began to emerge on the surface, especially on the tips of Te nanorods. ► Nearly monodispersed hexagonal CdTe nanoparticles with diameters of about 200 nm were finally obtained.

  8. Measurements of Charge Sharing Effects in Pixilated CZT/CdTe Detectors

    DEFF Research Database (Denmark)

    Kuvvetli, Irfan; Budtz-Jørgensen, Carl

    2007-01-01

    In this paper, charge sharing and charge loss effects in pixilated CZT/CdTe detectors are investigated by measurements. We measured charge sharing effects function of the inter-pixel gap (with same pixel pitch), the photon energy and the detector bias voltage for a large numbers of CZT and Cd......Te pixel detector samples. The results are used for the development of the large area X-ray and Gamma ray detector for the Atmosphere-Space Interactions Monitor (ASIM) planned for the ISS ESA Columbus module. Charge sharing measurements on detector samples with identical size and pixel geometry...

  9. X-ray Peltier cooled detectors for X-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Loupilov, A.; Sokolov, A.; Gostilo, V.

    2001-01-01

    The recent results on development of X-ray Si(Li), Si-planar and CdTe p-i-n detectors cooled by Peltier coolers for fabrication of laboratory and portable XRF analysers for different applications are discussed. Low detection limits of XRF analysers are provided by increasing of detectors sensitive surface; improvement of their spectrometrical characteristics; decreasing of front-end-electronics noise level; Peltier coolers and vacuum chambers cooling modes optimization. Solution of all mentioned tasks allowed to develop Peltier cooled detectors with the following performances: (1.) Si(Li) detectors: S=20 mm 2 , thickness=3.5 mm, 175 eV (5.9 keV), 430 eV (59.6 keV); S=100 mm 2 ; thickness=4.5 mm, 270 eV (5.9 keV), 485 eV (59.6 keV). (2.) Si-planar detector: S=10 mm 2 , thickness=0.4 mm, 230 eV (5.9 keV), 460 eV (59.6 keV). (3.) CdTe p-i-n detectors: S=16 mm 2 , thickness=0.5 mm, 350 eV (5.9 keV), 585 eV (59.6 keV). S=16 mm 2 , thickness=1.2 mm, 310 eV (5.9 keV), 600 eV (59.6 keV). Advantages and disadvantages of all types of detectors for X-ray fluorescence analysis are compared. Spectra are presented. Application of different XRF analysers based on developed detectors in medicine, environmental science, industry, cryminalistics and history of art are demonstrated

  10. X-ray Peltier cooled detectors for X-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Loupilov, A.; Sokolov, A.; Gostilo, V.

    2000-01-01

    The recent results on development of X-ray Si(Li), Si-planar and CdTe p-i- n detectors cooled by Peltier coolers for fabrication of laboratory and portable XRF analysers for different applications are discussed. Low detection limits of XRF analysers are provided by increasing of detectors sensitive surface; improvement of their spectrometrical characteristics; decreasing of front-end-electronics noise level; Peltier coolers and vacuum chambers cooling modes optimization. Solution of all mentioned tasks allowed to develop Peltier cooled detectors with the following performances: (1) Si(Li) detectors: S = 20 mm 2 , thickness = 3.5 mm, 175 eV (5.9 keV), 430 eV (59.6 keV); S = 100 mm 2 ; thickness = 4.5 mm, 270 eV (5.9 keV), 485 eV (59,6 keV). (2) Si-planar detector: S = 10 mm 2 , thickness = 0.4 mm, 230 eV (5.9 keV), 460 eV (59.6 keV). (3) CdTe p-i-n detectors: S = 16 mm 2 , thickness 0.5 mm, 350 eV (5.9 keV), 585 eV (59.6 keV). S = 16 mm 2 , thickness = 1.2 mm, 310 eV (5.9 keV), 600 eV (59.6 keV). Advantages and disadvantages of all types of detectors for X-ray fluorescence analysis are compared. Spectra are presented. Application of different XRF analysers based on developed detectors in medicine, environmental science, industry, criminalistics and history of art are demonstrated. (author)

  11. Simulation and Performance Test Technology Development for Semiconductor Radiation Detection Instrument Fabrication

    International Nuclear Information System (INIS)

    Kim, Jong Kyung; Lee, W. G.; Kim, S. Y.; Shin, C. H.; Kim, K. O.; Park, J. M.; Jang, D. Y.; Kang, J. S.

    2010-06-01

    - Analysis on the Absorbed Dose and Electron Generation by Using MCNPX Code - Analysis on the Change of Measured Energy Spectrum As a Function of Bias Voltage Applied in Semiconductor Detector - Comparison of Monte Carlo Simulation Considering the Charge Collection Efficiency and Experimental Result - Development of Semiconductor Sensor Design Code Based on the Graphic User Interface - Analysis on Depth Profile of Ion-implanted Semiconductor Wafer Surface and Naturally Generated SiO2 Insulation Layer Using Auger Electron Spectroscopy - Measurement of AFM Images and Roughness to Abalyze Surface of Semiconductor Wafer with respect to Annealing and Cleaning Process - Measurement of Physical Properties for Semiconductor Detector Surface after CZT Passivation Process - Evaluation of Crystal Structure and Specific Resistance of CZT - Measurement/Analysis on Band Structure of CZT Crystal - Evaluation of Neutron Convertor Layer with respect to Change in Temperature - Measurement/Evaluation of physical characteristics for lattice parameter, specific resistance, and band structure of CZT crystal - Measurement/Evaluation of lattice transition of SiC semiconductor detector after radiation irradiation - Measurement/Evaluation of performance of semiconductor detector with respect to exposure in high temperature environment

  12. Low frequency noise in semiconductor detectors

    International Nuclear Information System (INIS)

    Stojanovic, M.; Marjanovic, N.

    1998-01-01

    Noise characteristics of surface-barrier detectors based on Au contacts on n-Si were measured and analyzed. The metal layers were deposited by evaporation to 40-100 nm thickness. Standard surface-barrier detectors based on Au/Si structures are known to have favorable characteristics, but they tend to degrade with aging and under severe working conditions. Degradation is particularly related to the increase in noise level, leakage current and the reduction of detector efficiency and resolution. Therefore, practical applications of surface-barrier detectors demand their constant upgrading. Improvements of detector properties are concentrated mainly on the front surface and front (rectifying) contact. The aim was to improve the noise characteristics of the surface-barrier structures and retain the favorable detector properties of the Au/Si system. (authors)

  13. Advanced far infrared detectors

    International Nuclear Information System (INIS)

    Haller, E.E.

    1993-05-01

    Recent advances in photoconductive and bolometric semiconductor detectors for wavelength 1 mm > λ > 50 μm are reviewed. Progress in detector performance in this photon energy range has been stimulated by new and stringent requirements for ground based, high altitude and space-borne telescopes for astronomical and astrophysical observations. The paper consists of chapters dealing with the various types of detectors: Be and Ga doped Ge photoconductors, stressed Ge:Ga devices and neutron transmutation doped Ge thermistors. Advances in the understanding of basic detector physics and the introduction of modern semiconductor device technology have led to predictable and reliable fabrication techniques. Integration of detectors into functional arrays has become feasible and is vigorously pursued by groups worldwide

  14. Behaviour of semiconductor nuclear-particle detectors; Comportement des semi-conducteurs comme detecteurs de particules nucleaires; Povedenie detektorov yadernykh chastits na poluprovodnikakh; Propiedades de los detectores de particulas nucleares a base de semiconductores

    Energy Technology Data Exchange (ETDEWEB)

    Walter, F J; Dabbs, J W.T.; Roberts, L D [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    1962-04-15

    Experimental and theoretical studies of the behaviour of semiconductor nuclear-particle detectors have been carried out over the temperature range of 0.2{sup o}K to 300{sup o}K. A simple theoretical model for the detector behaviour, which is found to describe the observed behaviour over a wide range of parameters, is presented. The importance of semiconductor purity and bias voltage in connection with pulse height, pulse rise-time and detector area is discussed. Empirical studies of noise and energy resolution indicate that for alpha particles the smallest observed peak-widths are substantially larger than those expected on the basis of electrical noise from the detector and amplifier. Equivalent noise values of {<=} 3 keV full-width at half maximum (FWHM) have been found for a 40-mm{sup 2} silicon surface-barrier detector at 77{sup o}K. Semiconductor detectors exhibit a ''pulse-height defect'' for fission fragments. There is evidence that this defect is not caused by a ''dead layer''. If electric fields which are insufficient to insure complete ''collection'' are responsible for the defect, the necessary minimum field (at the surface) is > 3 x 10{sup 4} V/cm for fission fragments, as compared to the value of 2 x 10{sup 3} V/cm which is found necessary in the case of alpha particles in Ge and Si. Detailed considerations regarding pulse rise-time at the amplifier have shown that in high-resistivity material both the ''dielectric'' relaxation time and the resistance associated with the undepleted base material can play an important role. A quantative description of the effect of detector and amplifier parameters on the shapes and rise-times associated with the pulse are presented. The advantages and problems associated with the use of surface-barrier detectors in several unique low-temperature nuclear-alignment experiments are discussed. These experiments involved fission-fragment angular distributions and resolution of alpha-fine structure with long-term stability

  15. Band structure of CdTe under high pressure

    International Nuclear Information System (INIS)

    Jayam, Sr. Gerardin; Nirmala Louis, C.; Amalraj, A.

    2005-01-01

    The band structures and density of states of cadmium telluride (CdTe) under various pressures ranging from normal to 4.5 Mbar are obtained. The electronic band structure at normal pressure of CdTe (ZnS structure) is analyzed and the direct band gap value is found to be 1.654 eV. CdTe becomes metal and superconductor under high pressure but before that it undergoes structural phase transition from ZnS phase to NaCl phase. The equilibrium lattice constant, bulk modulus and the phase transition pressure at which the compounds undergo structural phase transition from ZnS to NaCl are predicted from the total energy calculations. The density of states at the Fermi level (N(E F )) gets enhanced after metallization, which leads to the superconductivity in CdTe. In our calculation, the metallization pressure (P M = 1.935 Mbar) and the corresponding reduced volume ((V/V 0 ) M = 0.458) are estimated. Metallization occurs via direct closing of band gap at Γ point. (author)

  16. Synthesis and characterization of CdTe quantum dots by one-step method

    Directory of Open Access Journals (Sweden)

    H. Li

    2013-09-01

    Full Text Available L-Cysteine (Cys-capped CdTe quantum dots (QDs were prepared when sodium tellurite worked as a tellurium source and sodium borohydride acted as a reductant. The influences of various experimental variables, including pH values, Cd/Te and Cd/Cys molar ratios, on the photoluminescence (PL quantum yield (QY of the obtained CdTe QDs have been systematically investigated. Experimental results indicated that green to red emitting CdTe QDs with maximum quantum yield of 19.4% can be prepared at pH 11.5 and n(Cd2+:n(Te2−:n(Cys = 1:0.07:2.0. X-Ray powder diffraction (XRD and transmission electron microscopy (TEM were used to characterize the crystal structure and shape of CdTe QDs. The results showed that the prepared CdTe QDs were of cubic zinc blend crystal structure in a sphere-like shape.DOI: http://dx.doi.org/10.4314/bcse.v27i3.7

  17. Radiometric and dosimetric characteristics of HgI2 detectors

    International Nuclear Information System (INIS)

    Zaletin, V.M.; Krivozubov, O.V.; Torlin, M.A.; Fomin, V.I.

    1988-01-01

    The characteristics of HgI 2 detectors in x-ray and gamma detection in applications to radiometric and dosimetric monitoring and as portable instruments for such purposes was considered. Blocks with mosaic and sandwich structures were prepared and tested against each other and, for comparative purposes, against CdTe detectors for relative sensitivities at various gamma-quanta energies. Sensitivity dependencies on gamma radiation energy were plotted for the detector materials and structures as were current dependencies on the dose rate of x rays. Results indicated that the mercury iodide detectors could be used in radiometric and dosimetric measurements at gamma quantum energies up to and in excess of 1000 KeV

  18. Determination and stabilization of the altitude of an aircraft in space using semi-conductor detectors

    International Nuclear Information System (INIS)

    Gilly, L.

    1967-01-01

    The device studied in this report can be used as altimeter or as altitude stabilizer (B.F. number PV 100-107, March 23, 1967). It includes essentially a 'surface barrier' semiconductor detector which counts alpha particles of a radioactive source. Two sources are used corresponding to two possible utilizations of the device. This report describes experiences made in laboratory which comprises electronic tests and a physic study. Systematic analysis of experimental errors is made comparatively with aneroid altimeters. An industrial device project is given. (author) [fr

  19. Spin dynamics in bulk CdTe at room temperature

    International Nuclear Information System (INIS)

    Nahalkova, P.; Nemec, P.; Sprinzl, D.; Belas, E.; Horodysky, P.; Franc, J.; Hlidek, P.; Maly, P.

    2006-01-01

    In this paper, we report on the room temperature dynamics of spin-polarized carriers in undoped bulk CdTe. Platelets of CdTe with different concentration of preparation-induced dislocations were prepared by combining the mechanical polishing and chemical etching. Using the polarization-resolved pump-probe experiment in transmission geometry, we have observed a systematic decrease of both the signal polarization and the electron spin dephasing time (from 52 to 36 ps) with the increased concentration of defects. We have suggested that the Elliot-Yafet mechanism might be the dominant spin dephasing mechanism in platelets of CdTe at room temperature

  20. A facile route to shape controlled CdTe nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mntungwa, Nhlakanipho; Rajasekhar, Pullabhotla V.S.R. [Department of Chemistry, University of Zululand, Private Bag X1001, KwaDlangezwa 3886, Empangeni, KZN (South Africa); Revaprasadu, Neerish, E-mail: nrevapra@pan.uzulu.ac.za [Department of Chemistry, University of Zululand, Private Bag X1001, KwaDlangezwa 3886, Empangeni, KZN (South Africa)

    2011-04-15

    Research highlights: {yields} A facile hybrid solution based/thermolysis route has been used for the synthesis of hexadecylamine capped CdTe nanoparticles. {yields} This method involves the reaction by the addition of an aqueous suspension of a cadmium salt to a freshly prepared NaHTe solution. {yields} The cadmium salt plays an important role in the growth mechanism of the particles and hence its final morphology. - Abstract: Hexadecylamine (HDA) capped CdTe nanoparticles have been synthesized using a facile hybrid solution based/thermolysis route. This method involves the reaction by the addition of an aqueous suspension or solution of a cadmium salt (chloride, acetate, nitrate or carbonate) to a freshly prepared NaHTe solution. The isolated CdTe was then dispersed in tri-octylphosphine (TOP) and injected into pre-heated HDA at temperatures of 190, 230 and 270 deg. C for 2 h. The particle growth and size distribution of the CdTe particles synthesized using cadmium chloride as the cadmium source were monitored using absorption and photoluminescence spectroscopy. The final morphology of the CdTe nanoparticles synthesized from the various cadmium sources was studied by transmission electron microscopy (TEM) and high resolution TEM. The cadmium source has an influence on the final morphology of the particles.

  1. A facile route to shape controlled CdTe nanoparticles

    International Nuclear Information System (INIS)

    Mntungwa, Nhlakanipho; Rajasekhar, Pullabhotla V.S.R.; Revaprasadu, Neerish

    2011-01-01

    Research highlights: → A facile hybrid solution based/thermolysis route has been used for the synthesis of hexadecylamine capped CdTe nanoparticles. → This method involves the reaction by the addition of an aqueous suspension of a cadmium salt to a freshly prepared NaHTe solution. → The cadmium salt plays an important role in the growth mechanism of the particles and hence its final morphology. - Abstract: Hexadecylamine (HDA) capped CdTe nanoparticles have been synthesized using a facile hybrid solution based/thermolysis route. This method involves the reaction by the addition of an aqueous suspension or solution of a cadmium salt (chloride, acetate, nitrate or carbonate) to a freshly prepared NaHTe solution. The isolated CdTe was then dispersed in tri-octylphosphine (TOP) and injected into pre-heated HDA at temperatures of 190, 230 and 270 deg. C for 2 h. The particle growth and size distribution of the CdTe particles synthesized using cadmium chloride as the cadmium source were monitored using absorption and photoluminescence spectroscopy. The final morphology of the CdTe nanoparticles synthesized from the various cadmium sources was studied by transmission electron microscopy (TEM) and high resolution TEM. The cadmium source has an influence on the final morphology of the particles.

  2. HgCdTe photovoltaic detectors on Si substrates

    International Nuclear Information System (INIS)

    Zanio, K.R.; Bean, R.C.

    1988-01-01

    HgCdTe photovoltaic detectors have been fabricated on Si substrates through intermediate CdTe/GaAs layers. Encapsulation of the GaAs between the CdTe and Si prevents unintentional doping of the HgCdTe by Ga and As. Uniform epitaxial GaAs is grown on three inch diameter Si substrates. Detectors on such large area Si substrates will offer hybrid focal plane arrays whose dimensions are not limited by the difference between the coefficients of thermal expansion of the Si signal processor and the substrate for the HgCdTe detector array. The growth of HgCdTe detectors on the Si signal processors for monolithic focal plane arrays is also considered. 40 references

  3. 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

  4. The High Energy Detector of Simbol-X

    Science.gov (United States)

    Meuris, A.; Limousin, O.; Lugiez, F.; Gevin, O.; Blondel, C.; Le Mer, I.; Pinsard, F.; Cara, C.; Goetschy, A.; Martignac, J.; Tauzin, G.; Hervé, S.; Laurent, P.; Chipaux, R.; Rio, Y.; Fontignie, J.; Horeau, B.; Authier, M.; Ferrando, P.

    2009-05-01

    The High Energy Detector (HED) is one of the three detection units on board the Simbol-X detector spacecraft. It is placed below the Low Energy Detector so as to collect focused photons in the energy range from 8 to 80 keV. It consists of a mosaic of 64 independent cameras, divided in 8 sectors. Each elementary detection unit, called Caliste, is the hybridization of a 256-pixel Cadmium Telluride (CdTe) detector with full custom front-end electronics into a unique component. The status of the HED design will be reported. The promising results obtained from the first micro-camera prototypes called Caliste 64 and Caliste 256 will be presented to illustrate the expected performance of the instrument.

  5. The High Energy Detector of Simbol-X

    International Nuclear Information System (INIS)

    Meuris, A.; Limousin, O.; Blondel, C.; Le Mer, I.; Pinsard, F.; Cara, C.; Goetschy, A.; Martignac, J.; Laurent, P.; Chipaux, R.; Rio, Y.; Fontignie, J.; Horeau, B.; Ferrando, P.; Lugiez, F.; Gevin, O.; Tauzin, G.; Herve, S.; Authier, M.

    2009-01-01

    The High Energy Detector (HED) is one of the three detection units on board the Simbol-X detector spacecraft. It is placed below the Low Energy Detector so as to collect focused photons in the energy range from 8 to 80 keV. It consists of a mosaic of 64 independent cameras, divided in 8 sectors. Each elementary detection unit, called Caliste, is the hybridization of a 256-pixel Cadmium Telluride (CdTe) detector with full custom front-end electronics into a unique component. The status of the HED design will be reported. The promising results obtained from the first micro-camera prototypes called Caliste 64 and Caliste 256 will be presented to illustrate the expected performance of the instrument.

  6. Semiconductor radiation detectors: device physics

    National Research Council Canada - National Science Library

    Lutz, Gerhard

    1999-01-01

    ..., including nuclear physics, elementary particle physics, optical and x-ray astronomy, medicine, and materials testing - and the number of applications is growing continually. Closely related, and initiated by the application of semiconductors, is the development of low-noise low-power integrated electronics for signal readout. The success of semicond...

  7. A pixel design for X-ray imaging with CdTe sensors

    Energy Technology Data Exchange (ETDEWEB)

    Lambropoulos, C.P.; Zervakis, E.G. [Technological Educational Institute of Halkis, Psahna - Evia (Greece); Loukas, D. [Institute of Nuclear Physics, NCSR Demokritos, Agia Paraskevi - Attiki (Greece)

    2008-07-01

    A readout architecture appropriate for X-ray Imaging using charge integration has been designed. Each pixel consists of a capacitive transimpedance amplifier, a sample and hold circuit a comparator and an 8 bit DRAM. Pixel level A/D conversion and local storage of the digitized signal is performed. The target sensors are 100{mu}m x 100 {mu}m CdTe pixel detectors and integration time of 1ms or less can be achieved. Special measures have been taken to minimize the gain fixed pattern noise and the reset noise, while purely digital correlation double sampling can be performed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. A pixel design for X-ray imaging with CdTe sensors

    International Nuclear Information System (INIS)

    Lambropoulos, C.P.; Zervakis, E.G.; Loukas, D.

    2008-01-01

    A readout architecture appropriate for X-ray Imaging using charge integration has been designed. Each pixel consists of a capacitive transimpedance amplifier, a sample and hold circuit a comparator and an 8 bit DRAM. Pixel level A/D conversion and local storage of the digitized signal is performed. The target sensors are 100μm x 100 μm CdTe pixel detectors and integration time of 1ms or less can be achieved. Special measures have been taken to minimize the gain fixed pattern noise and the reset noise, while purely digital correlation double sampling can be performed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Interface properties of MIS structures based on hetero-epitaxial graded-gap Hg1-xCdxTe with CdTe interlayer created in situ during MBE growth

    Science.gov (United States)

    Voitsekhovskii, Alexander V.; Nesmelov, Sergey N.; Dzyadukh, Stanislav M.; Varavin, Vasily S.; Dvoretsky, Sergey A.; Mikhailov, Nikolay N.; Yakushev, Maksim V.; Sidorov, Georgy Yu.

    2017-11-01

    Heterostructures based on n-Hg1-xCdxTe (x = 0.23-0.40) with near-surface graded-gap layers were grown by molecular beam epitaxy on Si (013) substrates. At 77 K, the admittance of the In/Al2O3/Hg1-xCdxTe metal-insulator-semiconductor (MIS) structures with grown in situ CdTe intermediate layer and without such a layer was investigated. It has been established that MIS structures of In/Al2O3/Hg1-xCdxTe with an interlayer of in situ grown CdTe are characterized by the electrical strength of the dielectric and the qualitative interface. The hysteresis of the capacitive characteristics is practically absent within a small range of variation in the bias voltage. The density of fast surface states at the minimum does not exceed 2.2 × 1010 eV-1 cm-2. MIS structures of In/Al2O3/Hg1-xCdxTe without an intermediate layer of CdTe have significantly higher densities of fast and slow surface states, as well as lower values of the differential resistance of the space-charge region in the regime of strong inversion.

  10. Interaction and energy transfer studies between bovine serum albumin and CdTe quantum dots conjugates: CdTe QDs as energy acceptor probes.

    Science.gov (United States)

    Kotresh, M G; Inamdar, L S; Shivkumar, M A; Adarsh, K S; Jagatap, B N; Mulimani, B G; Advirao, G M; Inamdar, S R

    2017-06-01

    In this paper, a systematic investigation of the interaction of bovine serum albumin (BSA) with water-soluble CdTe quantum dots (QDs) of two different sizes capped with carboxylic thiols is presented based on steady-state and time-resolved fluorescence measurements. Efficient Förster resonance energy transfer (FRET) was observed to occur from BSA donor to CdTe acceptor as noted from reduction in the fluorescence of BSA and enhanced fluorescence from CdTe QDs. FRET parameters such as Förster distance, spectral overlap integral, FRET rate constant and efficiency were determined. The quenching of BSA fluorescence in aqueous solution observed in the presence of CdTe QDs infers that fluorescence resonance energy transfer is primarily responsible for the quenching phenomenon. Bimolecular quenching constant (k q ) determined at different temperatures and the time-resolved fluorescence data provide additional evidence for this. The binding stoichiometry and various thermodynamic parameters are evaluated by using the van 't Hoff equation. The analysis of the results suggests that the interaction between BSA and CdTe QDs is entropy driven and hydrophobic forces play a key role in the interaction. Binding of QDs significantly shortened the fluorescence lifetime of BSA which is one of the hallmarks of FRET. The effect of size of the QDs on the FRET parameters are discussed in the light of FRET parameters obtained. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Spatiotemporal Monte Carlo transport methods in x-ray semiconductor detectors: application to pulse-height spectroscopy in a-Se.

    Science.gov (United States)

    Fang, Yuan; Badal, Andreu; Allec, Nicholas; Karim, Karim S; Badano, Aldo

    2012-01-01

    The authors describe a detailed Monte Carlo (MC) method for the coupled transport of ionizing particles and charge carriers in amorphous selenium (a-Se) semiconductor x-ray detectors, and model the effect of statistical variations on the detected signal. A detailed transport code was developed for modeling the signal formation process in semiconductor x-ray detectors. The charge transport routines include three-dimensional spatial and temporal models of electron-hole pair transport taking into account recombination and trapping. Many electron-hole pairs are created simultaneously in bursts from energy deposition events. Carrier transport processes include drift due to external field and Coulombic interactions, and diffusion due to Brownian motion. Pulse-height spectra (PHS) have been simulated with different transport conditions for a range of monoenergetic incident x-ray energies and mammography radiation beam qualities. Two methods for calculating Swank factors from simulated PHS are shown, one using the entire PHS distribution, and the other using the photopeak. The latter ignores contributions from Compton scattering and K-fluorescence. Comparisons differ by approximately 2% between experimental measurements and simulations. The a-Se x-ray detector PHS responses simulated in this work include three-dimensional spatial and temporal transport of electron-hole pairs. These PHS were used to calculate the Swank factor and compare it with experimental measurements. The Swank factor was shown to be a function of x-ray energy and applied electric field. Trapping and recombination models are all shown to affect the Swank factor.

  12. The physics and technology of Si and Ge detectors

    International Nuclear Information System (INIS)

    Stab, Lucien

    Semiconductor physics fundamentals are recalled (energy levels in crystalline solids, level population, charge carrier transport) as an introduction to studying NP junction at thermal equilibrium, or reversly biased. The fabrication of semiconductor detectors including surface barrier detectors, implanted junctions, and lithium-drifted semiconductors is discussed [fr

  13. [Oxidative damage effects induced by CdTe quantum dots in mice].

    Science.gov (United States)

    Xie, G Y; Chen, W; Wang, Q K; Cheng, X R; Xu, J N; Huang, P L

    2017-07-20

    Objective: To investigate Oxidative damage effects induced by CdTe Quantum Dots (QDs) in mice. Methods: 40 ICR mice were randomly divided into 5 groups: one control group (normal saline) ; four CdTe QDs (exposed by intravenous injection of 0.2 ml of CdTe QDs at the concentration of 0、0.5、5.0、50.0 and 500.0 nmol/ml respectively) . After 24 h, the mice were decapitated and the blood was collected for serum biochemically indexes、hematology indexes, the activities of SOD、GSH-Px and the concentration of MDA were all detected. Results: The results showed in the four CdTe QDs exposure groups, the level of CRE、PLT and the concentration of MDA were all significantly lower than those of the control group ( P control group ( P <0.01) . Conclusion: It was suggested that CdTe QDs at 0.5 nmol/ml could induce Oxidative damage effects in mice.

  14. Translocation and neurotoxicity of CdTe quantum dots in RMEs motor neurons in nematode Caenorhabditis elegans

    International Nuclear Information System (INIS)

    Zhao, Yunli; Wang, Xiong; Wu, Qiuli; Li, Yiping; Wang, Dayong

    2015-01-01

    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 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

  15. Semiconductor drift chamber: an application of a novel charge transport scheme

    International Nuclear Information System (INIS)

    Gatti, E.; Rehak, P.

    1983-08-01

    The purpose of this paper is to describe a novel charge tranport scheme in semiconductors in which the field responsible for the charge transport is independent of the depletion field. The application of the novel charge transport scheme leads to the following new semiconductor detectors: (1) Semiconductor Draft Chamber; (2) Ultra low capacitance - large semiconductor x-ray spectrometers and photodiodes; and (3) Fully depleted thick CCD. Special attention is paid to the concept of the Semiconductor Draft Chamber as a position sensing detector for high energy charged particles. Position resolution limiting factors are considered, and the values of the resolutions are given

  16. Development of the mercury iodide semiconductor crystal for application as a radiation detector

    International Nuclear Information System (INIS)

    Martins, Joao Francisco Trencher

    2011-01-01

    In this work, the establishment of a technique for HgI growth and preparation of crystals, for use as room temperature radiation semiconductor detectors is described. Three methods of crystal growth were studied while developing this work: physical vapor transport (PVT); saturated solution of HgI 2 , using two different solvents; (a) dimethyl sulfoxide (DMSO) and (b) acetone, and the Bridgman method. In order to evaluate the obtained crystals by the three methods, systematic measurements were carried out for determining the stoichiometry, structure, orientation, surface morphology and impurity of the crystal. The influence of these physical chemical properties on the crystals development was studied, evaluating their performance as radiation detectors. The X-ray diffractograms indicated that the crystals were, preferentially, oriented in the (001) e (101) directions with tetragonal structure for all crystals. Nevertheless, morphology with a smaller deformation level was observed for the crystal obtained by the PVT technique, comparing to other methods. Uniformity on the surface layer of the PVT crystal was detected, while clear incrustations of elements distinct from the crystal could be viewed on the DMSO crystal surface. The best results as to radiation response were found for the crystal grown by physical vapor transport. Significant improvement in the HgI z2 radiation detector performance was achieved for purer crystals, growing the crystal twice by PVT technique. (author)

  17. 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.

  18. Ultrafast spin injection from Cd1-x Mn x Te magnetic barriers into a CdTe quantum well studied by pump-probe spectroscopy

    International Nuclear Information System (INIS)

    Aoshima, I.; Nishibayashi, K.; Souma, I.; Murayama, A.; Oka, Y.

    2006-01-01

    Spin injection from diluted magnetic semiconductor (DMS) barriers of Cd 1- x Mn x Te into a quantum well (QW) of CdTe is studied, by means of pump-probe absorption spectroscopy in magnetic fields. Fast decay characteristics of circularly polarized differential absorbances of spin-polarized excitons in the DMS barrier show the exciton injection time of 6 ps from the barriers into the QW. In accordance with the fast relaxation of the spin-polarized excitons from the barrier, we observe the rise of circular polarization degree for the differential absorption of the CdTe QW in magnetic fields, evidently indicating the spin injection. In addition, the circular polarization degree up to 0.3 is developed in the well immediately after pumping, originating from the fast relaxation of a heavy hole (hh) spin less than 0.2 ps, due to the giant Zeeman effect caused by the penetration of the hh wave function into the DMS barriers

  19. Microwave studies on the dielectric properties of Sm3+ and Sm3+/CdTe doped sol-gel silica glasses

    International Nuclear Information System (INIS)

    Mathew, Siby; Rejikumar, P.R.; Yohannan, Jaimon; Mathew, K.T.; Unnikrishnan, N.V.

    2008-01-01

    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 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 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

  20. Synthesis and characterization of TGA-capped CdTe nanoparticles embedded in PVA matrix

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, S.K.; Kaur, Ramneek; Sharma, Mamta [Panjab University, Department of Physics, Center of Advanced Study in Physics, Chandigarh (India)

    2014-10-25

    This paper reports the synthesis and characterization of TGA-capped CdTe nanoparticles and its nanocomposite in a PVA matrix prepared by ex situ technique. The crystallite sizes of the CdTe nanoparticles and nanocomposite calculated from X-ray diffraction patterns are 6.07 and 7.75 nm with hexagonal structure, respectively. The spherical nature of the CdTe nanoparticles is confirmed from transmission electron microscopy measurements. Fourier transform infrared spectroscopy shows good interaction between the CdTe nanoparticles and PVA matrix. The absorption and emission spectra have also been studied. The stability of the TGA-capped CdTe nanoparticles increases after dispersion in a PVA matrix. In electrical measurements, the dark conductivity and the steady-state photoconductivity of CdTe nanocomposite thin films have been studied. The effect of temperature and intensity on the transient photoconductivity of CdTe nanocomposite is also studied. The values of differential life time have been calculated from the decay of photocurrent with time. The non-exponential decay of photoconductivity is observed indicating that the traps exist at all the energies in the band gap, making these materials suitable for various optoelectronic devices. (orig.)

  1. Synthesis and characterization of TGA-capped CdTe nanoparticles embedded in PVA matrix

    International Nuclear Information System (INIS)

    Tripathi, S.K.; Kaur, Ramneek; Sharma, Mamta

    2015-01-01

    This paper reports the synthesis and characterization of TGA-capped CdTe nanoparticles and its nanocomposite in a PVA matrix prepared by ex situ technique. The crystallite sizes of the CdTe nanoparticles and nanocomposite calculated from X-ray diffraction patterns are 6.07 and 7.75 nm with hexagonal structure, respectively. The spherical nature of the CdTe nanoparticles is confirmed from transmission electron microscopy measurements. Fourier transform infrared spectroscopy shows good interaction between the CdTe nanoparticles and PVA matrix. The absorption and emission spectra have also been studied. The stability of the TGA-capped CdTe nanoparticles increases after dispersion in a PVA matrix. In electrical measurements, the dark conductivity and the steady-state photoconductivity of CdTe nanocomposite thin films have been studied. The effect of temperature and intensity on the transient photoconductivity of CdTe nanocomposite is also studied. The values of differential life time have been calculated from the decay of photocurrent with time. The non-exponential decay of photoconductivity is observed indicating that the traps exist at all the energies in the band gap, making these materials suitable for various optoelectronic devices. (orig.)

  2. Operation of CdZnTe Semiconductor Detectors in Liquid Scintillator for the COBRA Experiment

    International Nuclear Information System (INIS)

    Oldorf, Christian

    2015-08-01

    COBRA, the Cadmium-Zinc-Telluride O-neutrino double-Beta Research Apparatus, is an experiment aiming for the measurement of the neutrinoless double beta decay with several isotopes, in particular 116 Cd, 106 Cd and 130 Te. A highly granular large scale experiment with about 400 kg of CdZnTe semiconductor detectors is currently under development. To provide evidence for the neutrinoless double beta decay of 116 Cd, a background rate in the order of 10 -3 counts/keV/kg/a is needed to achieve the required half-life sensitivity of at least 2 . 10 26 years. To reach this target, the detectors have to be operated in a highly pure environment, shielded from external radiation. Liquid scintillator is a promising candidate as a circum fluent replacement for the currently used lacquer. Next to the function as highly pure passivation material, liquid scintillator also acts as a neutron shield and active veto for external gammas. Within this thesis, the design, construction and assembly of a test set-up is described. The operation of four CdZnTe detectors after several years of storage in liquid scintillator is demonstrated. Next to extensive material compatibility tests prior to the assembly, the commissioning of the set-up and the characterization of the detectors are shown. Finally, results concerning the background reduction capability of liquid scintillator and the detection of cosmic muons are presented and compared to a Monte Carlo simulation.

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

    International Nuclear Information System (INIS)

    Unruh, Troy C.; Bellinger, Steven L.; Huddleston, David E.; McNeil, Walter J.; Patterson, Eric; Sobering, Tim J.; McGregor, Douglas S.

    2009-01-01

    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 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.

  4. 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

  5. Semiconductor radiation detectors technology and applications

    CERN Document Server

    2018-01-01

    The aim of this book is to educate the reader on radiation detectors, from sensor to read-out electronics to application. Relatively new detector materials, such as CdZTe and Cr compensated GaAs, are introduced, along with emerging applications of radiation detectors. This X-ray technology has practical applications in medical, industrial, and security applications. It identifies materials based on their molecular composition, not densities as the traditional transmission equipment does. With chapters written by an international selection of authors from both academia and industry, the book covers a wide range of topics on radiation detectors, which will satisfy the needs of both beginners and experts in the field.

  6. Cryogenic semiconductor high-intensity radiation monitors

    International Nuclear Information System (INIS)

    Palmieri, V.G.; Bell, W.H.; Borer, K.; Casagrande, L.; Da Via, C.; Devine, S.R.H.; Dezillie, B.; Esposito, A.; Granata, V.; Hauler, F.; Jungermann, L.; Li, Z.; Lourenco, C.; Niinikoski, T.O.; Shea, V. O'; Ruggiero, G.; Sonderegger, P.

    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. Use of semiconductors in energy-dispersive X-ray analysis

    International Nuclear Information System (INIS)

    Schiekel, M.

    1983-01-01

    The state-of-the-art of the application of semiconductor detectors with high resolution for photon radiation in energy-dispersive spectrometers is reviewed. It is concluded that the use of semiconductor detectors results in an improvement of spectrometers and thus in a wider range of application. Characteristics of the spectrometers, such as energy resolution and efficiency, are discussed and possible applications indicated. (author)

  8. 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.

  9. Position-sensitive superconductor detectors

    International Nuclear Information System (INIS)

    Kurakado, M.; Taniguchi, K.

    2016-01-01

    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.

  10. Thick epitaxial CdTe films grown by close space sublimation on Ge substrates

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Q; Haliday, D P; Tanner, B K; Brinkman, A W [Department of Physics, University of Durham. Science Site, Durham, DH1 3LE (United Kingdom); Cantwell, B J; Mullins, J T; Basu, A [Durham Scientific Crystals Ltd., NetPark, Thomas Wright Way, Sedgefield, County Durham, TS21 3FD (United Kingdom)], E-mail: Q.Z.Jiang@durham.ac.uk

    2009-01-07

    This paper reports, for the first time, the successful growth of 200 {mu}m thick CdTe films on mis-oriented Ge(1 0 0) substrates by a cost-effective optimized close space sublimation method. It is found that, as the thickness increases to a few hundred micrometres, subgrains are formed probably as a result of the large density of dislocations and strain within the initial interfacial layers. The films are of high quality (x-ray rocking curve width {approx}100 arcsec) and high resistance ({approx}10{sup 9} {omega} cm), and are thus candidates for x-ray and {gamma}-ray detectors. (fast track communication)

  11. SiliPET: Design of an ultra-high resolution small animal PET scanner based on stacks of semi-conductor detectors

    International Nuclear Information System (INIS)

    Cesca, N.; Auricchio, N.; Di Domenico, G.; Zavattini, G.; Malaguti, R.; Andritschke, R.; Kanbach, G.; Schopper, F.

    2007-01-01

    We studied with Monte Carlo simulations, using the EGSnrc code, a new scanner for small animal positron emission tomography (PET), based on stacks of double-sided semiconductor detectors. Each stack is composed of planar detectors with dimension 70x60x1 mm 3 and orthogonal strips on both sides with 500 μm pitch to read the two interaction coordinates, the third being the detector number in the stack. Multiple interactions in a stack are discarded. In this way, we achieve a precise determination of the first interaction point of the two 511 keV photons. The reduced dimensions of the scanner also improve the solid angle coverage resulting in a high sensitivity. Preliminary results of scanners based on Si planar detectors are presented and the initial tomographic reconstructions demonstrate very good spatial resolution limited only by the positron range. This suggests that, this is a promising new approach for small animal PET imaging. We are testing some double-sided silicon detectors, equipped with 128 orthogonal p and n strips on opposite sides using VATAGP3 ASIC by IDEAS

  12. 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)

  13. Photoluminescence properties of a novel conjugate of water-soluble CdTe quantum dots to guanine

    Energy Technology Data Exchange (ETDEWEB)

    Feng Xuejiao [North-East Normal University, Changchun 130024 (China); Shang, Qingkun, E-mail: shangqk995@nenu.edu.c [North-East Normal University, Changchun 130024 (China); Liu Hongjian [Relia Diagnostic Systems, Burlingame, CA 94010 (United States); Wang Wenlan; Wang Zhidan; Liu Junyu [North-East Normal University, Changchun 130024 (China)

    2010-04-15

    A novel conjugate of water-soluble CdTe quantum dots to a small biomolecule guanine has been obtained in aqueous phase. The photoluminescence property and the stability of the conjugate increased comparing to CdTe QDs. The interaction between CdTe QDs and guanine was studied by TEM, fluorescence microscope and photoluminescence (PL), IR, UV-Vis spectra. The effects of reflux time, pH value, ionic strength, and the ratio of CdTe QDs to guanine on the photoluminescence properties of conjugate were investigated in detail. The results show that guanine has a great influence on both the photoluminescence property and stability of thioglycolic acid-stabilized CdTe QDs. The formation of coordination and hydrogen bond between guanine molecules and CdTe including thioglycolic acid on its surface may effectively enhance the PL intensity and stability of CdTe QDs. The maximum PL intensity of the conjugate was obtained on the condition with lower ionic strength, less than 30 min reflux time, neutral pH value and 6/1 as molar ratio of guanine to CdTe.

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

    International Nuclear Information System (INIS)

    Accorsi, R.; Autiero, M.; Celentano, L.

    2007-01-01

    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 256x256 matrix of 55 μm square pixels) operating in single photon counting for detection of gamma-rays with low and medium energy (e.g. 125 I, 27-35 keV, 99m Tc, 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

  15. Measurement of neutron flux distribution by semiconductor detector; merenje raspodele neutronskog fluksa poluprovodnickim detektorom

    Energy Technology Data Exchange (ETDEWEB)

    Obradovic, D; Bosevski, T [Institut za nuklearne nauke Boris Kidric, Vinca, Beograd (Yugoslavia)

    1964-07-01

    Application of semiconductor detectors for measuring neutron flux distribution is about 10 times faster than measurements by activation foils and demands significantly lower reactor power. Following corrections are avoided: mass of activation foils which influences the self shielding, nuclear decay during activity measurements; counter dead-time. It is possible to control the measured data during experiment and repeat measurements if needed. Precision of the measurement is higher since it is possible to choose the wanted statistics. The method described in this paper is applied for measurements at the RB reactor. It is concluded that the method is suitable for fast measurements but the activation analysis is still indispensable.

  16. Doping of polycrystalline CdTe for high-efficiency solar cells on flexible metal foil.

    Science.gov (United States)

    Kranz, Lukas; Gretener, Christina; Perrenoud, Julian; Schmitt, Rafael; Pianezzi, Fabian; La Mattina, Fabio; Blösch, Patrick; Cheah, Erik; Chirilă, Adrian; Fella, Carolin M; Hagendorfer, Harald; Jäger, Timo; Nishiwaki, Shiro; Uhl, Alexander R; Buecheler, Stephan; Tiwari, Ayodhya N

    2013-01-01

    Roll-to-roll manufacturing of CdTe solar cells on flexible metal foil substrates is one of the most attractive options for low-cost photovoltaic module production. However, various efforts to grow CdTe solar cells on metal foil have resulted in low efficiencies. This is caused by the fact that the conventional device structure must be inverted, which imposes severe restrictions on device processing and consequently limits the electronic quality of the CdTe layer. Here we introduce an innovative concept for the controlled doping of the CdTe layer in the inverted device structure by means of evaporation of sub-monolayer amounts of Cu and subsequent annealing, which enables breakthrough efficiencies up to 13.6%. For the first time, CdTe solar cells on metal foil exceed the 10% efficiency threshold for industrialization. The controlled doping of CdTe with Cu leads to increased hole density, enhanced carrier lifetime and improved carrier collection in the solar cell. Our results offer new research directions for solving persistent challenges of CdTe photovoltaics.

  17. Study and modelling of the new generation Cd(Zn)Te X and gamma-ray detectors for space applications

    International Nuclear Information System (INIS)

    Dirks, Bob-Petrus-Franciscus

    2006-01-01

    The scientific astrophysics community needs a new instrument to gain more insight in the origin of the cosmic X-ray background, the physics of black holes and particle acceleration mechanisms in the energy range between 0.5 to 80 keV. Existing instruments like Chandra and XMM-Newton show very good results up to ∼10 keV but lack sufficient sensitivity above this value. In order to keep or improve the same performances up to ∼80 keV, grazing incidence mirrors with a large focal length of at least 20 m should be used. Since satellites this big cannot be launched with existing launchers, the mirror and detector must be placed on two different satellites flying in formation. The Simbol-X space mission will be the first project of this type. A high sensitivity at 80 keV requires not only a long focal length but also a detection unit with high spatial resolution, using detectors that are still efficient at these relatively high energies. CEA/Saclay/DAPNIA is developing this crucial element for the Simbol-X space mission. The imager consists of several modules, each built from individual X-ray mini-cameras. A single camera is a hybridisation of custom read-out electronics connected to a Cd(Zn)Te semiconductor crystal. The ensemble must be able to efficiently detect photons of up to 80 keV with an energy resolution of ∼1.3 keV (FWHM) at 68 keV. Furthermore it must be equipped with small pixels (∼500*500 μm"2) to attain the desired spatial resolution of 15 arcsec. In order to reach a good sensitivity and energy resolution, ultra-low noise read-out electronics in combination with high-quality semiconductor crystals are mandatory. The read-out electronics, baptised IDeF-X (Imaging Detector Front-end for X-rays), is also developed by CEA/Saclay. A thorough understanding of its functioning as well as its testing forms a part of this work. The spectroscopic performance of the detector is directly related to the electronics noise. The noise characteristics of the ASIC are

  18. Biaxially oriented CdTe films on glass substrate through nanostructured Ge/CaF2 buffer layers

    Science.gov (United States)

    Lord, R. J.; Su, P.-Y.; Bhat, I.; Zhang, S. B.; Lu, T.-M.; Wang, G.-C.

    2015-09-01

    Heteroepitaxial CdTe films were grown by metal organic chemical vapor deposition on glass substrates through nanostructured Ge/CaF2 buffer layers which were biaxially oriented. It allows us to explore the structural properties of multilayer biaxial semiconductor films which possess small angle grain boundaries and to test the principle of a solar cell made of such low-cost, low-growth-temperature semiconductor films. Through the x-ray diffraction and x-ray pole figure analysis, the heteroepitaxial relationships of the mutilayered films are determined as [111] in the out-of-plane direction and CdTe//Ge//{ }{{{CaF}}2} in the in-plane direction. The I-V curves measured from an ITO/CdS/CdTe/Ge/CaF2/glass solar cell test structure shows a power conversion efficiency of ˜η = 1.26%, illustrating the initial success of such an approach. The observed non-ideal efficiency is believed to be due to a low shunt resistance and high series resistance as well as some residual large-angle grain boundary effects, leaving room for significant further improvement.

  19. Electron injection in semiconductor drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.; Longoni, A.; Sampietro, M.; Castoldi, A.; Vacchi, A.

    1990-01-01

    The paper reports the first successful results of a simple MOS structure to inject electrons at a given position in Silicon Drift Detectors. The structure allows on-line calibration of the drift velocity of electrons within the detector. The calibration is a practical method to trace the temperature dependence of the electron mobility. Several of these injection structures can be implemented in silicon drift detectors without additional steps in the fabrication process. 5 refs., 11 figs

  20. Study and realization of a multi channel analyzer for a per operator probe

    International Nuclear Information System (INIS)

    Yahyaoui, Sarra; Brini, Borhen

    2006-01-01

    The goal of this project is to study and produce a Multi Channel Analyzer (MCA) prototype based on a microcontroller PIC 16F877. This prototype comprises an amplification and a peak detection parts. The microcontroller provide the analog to numeric conversion and ensures the communication with PC. This MCA will be connected to a per operator probe containing a semiconductor detector CdTe. (author). 7 refs

  1. Development of Small-Pixel CZT Detectors for Future High-Resolution Hard X-ray Missions

    Science.gov (United States)

    Beilicke, Matthias

    Owing to recent breakthroughs in grazing incidence mirror technology, next-generation hard X-ray telescopes will achieve angular resolutions of between 5 and 10 arc seconds - about an order of magnitude better than that of the NuSTAR hard X-ray telescope. As a consequence, the next generation of hard X-ray telescopes will require pixelated hard X- ray detectors with pixels on a grid with a lattice constant of between 120 and 240 um. Additional detector requirements include a low energy threshold of less than 5 keV and an energy resolution of less than 1 keV. The science drivers for a high angular-resolution hard X-ray mission include studies and measurements of black hole spins, the cosmic evolution of super-massive black holes, AGN feedback, and the behavior of matter at very high densities. We propose a R&D research program to develop, optimize and study the performance of 100-200 um pixel pitch CdTe and Cadmium Zinc Telluride (CZT) detectors of 1-2 mm thickness. Our program aims at a comparison of the performance achieved with CdTe and CZT detectors, and the optimization of the pixel, steering grid, and guard ring anode patterns. Although these studies will use existing ASICs (Application Specific Integrated Circuits), our program also includes modest funds for the development of an ultra-low noise ASIC with a 2-D grid of readout pads that can be directly bonded to the 100-200 um pixel pitch CdTe and CZT detectors. The team includes the Washington University group (Prof. M. Beilicke and Co-I Prof. H.S.W. Krawczynski et al.), and co-investigator G. De Geronimo at Brookhaven National Laboratory (BNL). The Washington University group has a 10 year track record of innovative CZT detector R&D sponsored by the NASA Astronomy and Physics Research and Analysis (APRA) program. The accomplishments to date include the development of CZT detectors with pixel pitches between 350 um and 2.5 mm for the ProtoExist, EXIST, and X-Calibur hard X-ray missions with some of the best

  2. Status and problems of semiconductor detectors

    International Nuclear Information System (INIS)

    Walton, J.T.; Goulding, F.S.; Haller, E.E.; Pehl, R.H.

    1981-03-01

    A brief review is given of the types of silicon and germanium detectors used or presently being developed for nuclear experiments. Large-area silicon and germanium detector telescopes for use in long-range particle detection and identification are emphasized. Large area position-sensitive detectors are also described. Some results are presented regarding radiation damage and damage repair by annealing. Evidence is also presented for the importance of producing large area silicon crystals of adequate quality to reduce trapping problems to negligible proportions

  3. Status and problems of semiconductor detectors

    Energy Technology Data Exchange (ETDEWEB)

    Walton, J.T.; Goulding, F.S.; Haller, E.E.; Pehl, R.H.

    1981-03-01

    A brief review is given of the types of silicon and germanium detectors used or presently being developed for nuclear experiments. Large-area silicon and germanium detector telescopes for use in long-range particle detection and identification are emphasized. Large area position-sensitive detectors are also described. Some results are presented regarding radiation damage and damage repair by annealing. Evidence is also presented for the importance of producing large area silicon crystals of adequate quality to reduce trapping problems to negligible proportions.

  4. RHEED studies of MBE growth mechanisms of CdTe and CdMnTe

    Energy Technology Data Exchange (ETDEWEB)

    Waag, A.; Behr, T.; Litz, T.; Kuhn-Heinrich, B.; Hommel, D.; Landwehr, G. (Physikalisches Inst., Univ. Wuerzburg (Germany))

    1993-01-30

    We report on reflection high energy electron diffraction (RHEED) studies of molecular beam epitaxy (MBE) growth of CdTe and CdMnTe on (100) oriented CdTe substrates. RHEED oscillations were measured for both the growth and desorption of CdTe and CdMnTe as a function of flux and temperature. For the first time, the influence of laser and electron irradiation on the growth rate, as well as desorption, of CdTe is studied in detail using RHEED oscillations. We found a very small effect on the growth rate as well as on the CdTe desorption rate. The growth rate of CdTe was determined for different temperatures and CdTe flux ratios. The obtained experimental results are compared with a kinetic growth model to get information on the underlying growth processes, taking into account the influence of a precursor by including surface diffusion. From the comparison between model and experimental results the sticking coefficients of Cd and Te are determined. The growth rate of CdMnTe increases with Mn flux. This dependence can be used to calibrate the Mn content during growth by comparing the growth rate of CdTe with the growth rate of CdMnTe. The change in growth rate has been correlated with Mn content via photoluminescence measurements. In addition, the sticking coefficient of Mn is derived by comparing experimental results with a kinetic growth model. For high manganese content a transition to three-dimensional growth occurs. (orig.).

  5. Improvements in Applied Gamma-Ray Spectrometry with Germanium Semiconductor Detector

    Energy Technology Data Exchange (ETDEWEB)

    Brune, D; Hellstroem, S [AB Atomenergi, Nykoeping (Sweden); Dubois, J [Chalmers University of Technology, Goeteborg (Sweden)

    1965-01-15

    A germanium semi-conductor detector has in the present investigation been used in four cases of applied gamma-ray spectrometry. In one case the weak-activity contribution of Cs{sup 134} in Cs{sup 137} standard sources has been determined. The second case concerns the determination of K{sup 42} in samples of biological origin containing strong Na{sup 24} activities. In the third case the Nb{sup 94} and Nb{sup 95} activities from neutron-irradiated niobium foils used in the dosimetry of high neutron fluxes with long exposure times have been completely resolved and it has been possible to determine the ratio of the two activities with a high degree of accuracy. Finally, a Zr{sup 95} - Nb{sup 95} source has been analysed in a similar way with respect to its radiochemical composition. The resolution obtained also made possible a determination of the branching ratio of the two gamma-transitions in Zr{sup 95} and of the energies of the gamma-transitions of both nuclides.

  6. CdTe polycrystalline films on Ni foil substrates by screen printing and their photoelectric performance

    International Nuclear Information System (INIS)

    Yao, Huizhen; Ma, Jinwen; Mu, Yannan; Su, Shi; Lv, Pin; Zhang, Xiaoling; Zhou, Liying; Li, Xue; Liu, Li; Fu, Wuyou; Yang, Haibin

    2015-01-01

    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 2 , which is higher than that of samples prepared at other temperatures. Furthermore, CdCl 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 2 treatment improved to 2.97 mA/cm 2 , indicating a potential application in photovoltaic devices

  7. Glutathione-capped CdTe nanocrystals as probe for the determination of fenbendazole

    Science.gov (United States)

    Li, Qin; Tan, Xuanping; Li, Jin; Pan, Li; Liu, Xiaorong

    2015-04-01

    Water-soluble glutathione (GSH)-capped CdTe quantum dots (QDs) were synthesized. In pH 7.1 PBS buffer solution, the interaction between GSH-capped CdTe QDs and fenbendazole (FBZ) was investigated by spectroscopic methods, including fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, and resonance Rayleigh scattering (RRS) spectroscopy. In GSH-capped CdTe QDs solution, the addition of FBZ results in the fluorescence quenching and RRS enhancement of GSH-capped CdTe QDs. And the quenching intensity (enhanced RRS intensity) was proportional to the concentration of FBZ in a certain range. Investigation of the interaction mechanism, proved that the fluorescence quenching and RRS enhancement of GSH-capped CdTe QDs by FBZ is the result of electrostatic attraction. Based on the quenching of fluorescence (enhancement of RRS) of GSH-capped CdTe QDs by FBZ, a novel, simple, rapid and specific method for FBZ determination was proposed. The detection limit for FBZ was 42 ng mL-1 (3.4 ng mL-1) and the quantitative determination range was 0-2.8 μg mL-1 with a correlation of 0.9985 (0.9979). The method has been applied to detect FBZ in real simples and with satisfactory results.

  8. Entangled γ-photons—classical laboratory exercise with modern detectors

    Science.gov (United States)

    Hetfleiš, Jakub; Lněnička, Jindřich; Šlégr, Jan

    2018-03-01

    This paper describes the application of modern semiconductor detectors of γ and β radiation, which can be used in undergraduate laboratory experiments and lecture demonstrations as a replacement for Geiger-Müller (GM) tubes. Unlike GM tubes, semiconductor detectors do not require a high voltage power source or shaping circuits. The principle of operation of semiconductor detectors is discussed briefly, and classical experiments from nuclear physics are described, ranging from the measurements of linear and mass attenuation coefficient to a demonstration of entangled γ-photons.

  9. A new metallic oxide semiconductor field effect transistor detector for use of in vivo dosimetry

    International Nuclear Information System (INIS)

    Qi Zhenyu; Deng Xiaowu; Huang Shaomin; Kang Dehua; Anatoly Rosenfeld

    2006-01-01

    Objective: To investigate the application of a recently developed metallic oxide semiconductor field effect transistor (MOSFET) detector for use in vivo dosimetry. Methods: The MOSFET detector was calibrated for X-ray beams of 8 MV and 15 MV, as well as electron beams with energy of 6,8,12 and 18 MeV. The dose linearity of the MOSFET detector was investigated for the doses ranging from 0 up to 50 Gy using 8 MV X-ray beams. Angular effect was evaluated as well in a cylindrical PMMA phantom by changing the beam entrance angle every 15 degree clockwise. The MOSFET detector was then used for a breast cancer patient in vivo dose measurement, after the treatment plan was verified in a water phantom using a NE-2571 ion chamber, in vivo measurements were performed in the first and last treatment, and once per week during the whole treatment. The measured doses were then compared with planning dose to evaluate the accuracy of each treatment. Results: The MOSFET detector represented a good energy response for X-ray beams of 8 MV and 15 MV, and for electron beams with energy of 6 MeV up to 18 MeV. With the 6 V bias, Dose linearity error of the MOSFET detector was within 3.0% up to approximately 50 Gy, which can be significantly reduced to 1% when the detector was calibrated before and after each measurement. The MOSFET response varied within 1.5% for angles from 270 degree to 90 degree. However, maximum error of 10.0% was recorded comparing MOSFET response between forward and backward direction. In vivo measurement for a breast cancer patient using 3DCRT showed that, the average dose deviation between measurement and calculation was 2.8%, and the maximum error was less then 5.0%. Conclusions: The new MOSFET detector, with its advantages of being in size, easy use, good energy response and dose linearity, can be used for in vivo dose measurement. (authors)

  10. Physical and optical properties of size-selective CdTe nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Fok, Alice [Department of Chemistry, The City College of New York, CUNY New York, NY 10031 (United States); Morales, Jorge [Department of Biology, City College of New York, CUNY New York, NY 10031 (United States); Sohel, Mohammad [Natural Sciences Department, Hostos College, CUNY Bronx, NY 10451 (United States)

    2010-06-15

    Physical and optical properties of colloidal cadmium telluride nanocrystals (CdTe NCs) were investigated. The CdTe NCs were synthesized by reacting elemental tellurium dissolved in tributylphosphine with a mixture of cadmium oxide, octadecene, and oleic acid. These NCs, which were characterized by transmission electron microscopy (TEM) are spherical and ranged from 5 to 7 nm in diameter. The identity of the compound post-synthesis was confirmed by X-Ray diffraction (XRD) patterns. UV-Vis and photoluminescence (PL) properties as grown and pure CdTe samples were investigated. Bright excitonic photoluminescence emission was observed (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. A basic component for ISGRI, the CdTe gamma camera on board the INTEGRAL satellite

    International Nuclear Information System (INIS)

    Arques, M.; Baffert, N.; Lattard, D.

    1999-01-01

    A basic component, called Polycell, has been developed for the ISGRI (INTEGRAL Soft Gamma Ray Imager) CdTe camera on board the INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) satellite. Operating at room temperature, it covers the 20 keV--1 MeV energy range. It features a sub-ensemble of 16 CdTe detectors and their associated front end electronics. This electronics is based on 4-channel analog-digital ASICs. Their analog part features a low noise preamplifier, allowing a threshold below 20 keV and a pulse rise-time measurement which permits a charge loss correction. The digital part ensures the internal acquisition timing sequence as well as the dialogue with external electronics. Two versions of the ISGRI ASIC have been developed in a collaboration of two CEA microelectronics teams from CEA/DTA/LETI/DSYS and CEA/DSM/DAPNIA/SEI, respectively on a standard CMOS AMS process hardened against radiation by lay-out, and on a Silicon On Insulator process (DMILL MHS), the latter being latch-up free. This paper presents the ASIC and polycell architecture as well as experimental results obtained with polycells equipped with AMS ASICs

  12. CdTe Based Hard X-ray Imager Technology For Space Borne Missions

    Science.gov (United States)

    Limousin, Olivier; Delagnes, E.; Laurent, P.; Lugiez, F.; Gevin, O.; Meuris, A.

    2009-01-01

    CEA Saclay has recently developed an innovative technology for CdTe based Pixelated Hard X-Ray Imagers with high spectral performance and high timing resolution for efficient background rejection when the camera is coupled to an active veto shield. This development has been done in a R&D program supported by CNES (French National Space Agency) and has been optimized towards the Simbol-X mission requirements. In the latter telescope, the hard X-Ray imager is 64 cm² and is equipped with 625µm pitch pixels (16384 independent channels) operating at -40°C in the range of 4 to 80 keV. The camera we demonstrate in this paper consists of a mosaic of 64 independent cameras, divided in 8 independent sectors. Each elementary detection unit, called Caliste, is the hybridization of a 256-pixel Cadmium Telluride (CdTe) detector with full custom front-end electronics into a unique 1 cm² component, juxtaposable on its four sides. Recently, promising results have been obtained from the first micro-camera prototypes called Caliste 64 and will be presented to illustrate the capabilities of the device as well as the expected performance of an instrument based on it. The modular design of Caliste enables to consider extended developments toward IXO type mission, according to its specific scientific requirements.

  13. 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

  14. Detector Motion Method to Increase Spatial Resolution in Photon-Counting Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Daehee; Park, Kyeongjin; Lim, Kyung Taek; Cho, Gyuseong [Korea Advanced Institute of Science and Technology, Daejon (Korea, Republic of)

    2017-03-15

    Medical imaging requires high spatial resolution of an image to identify fine lesions. Photoncounting detectors in medical imaging have recently been rapidly replacing energy-integrating detectors due to the former's high spatial resolution, high efficiency and low noise. Spatial resolution in a photon counting image is determined by the pixel size. Therefore, the smaller the pixel size, the higher the spatial resolution that can be obtained in an image. However, detector redesigning is required to reduce pixel size, and an expensive fine process is required to integrate a signal processing unit with reduced pixel size. Furthermore, as the pixel size decreases, charge sharing severely deteriorates spatial resolution. To increase spatial resolution, we propose a detector motion method using a large pixel detector that is less affected by charge sharing. To verify the proposed method, we utilized a UNO-XRI photon-counting detector (1-mm CdTe, Timepix chip) at the maximum X-ray tube voltage of 80 kVp. A similar spatial resolution of a 55-μm-pixel image was achieved by application of the proposed method to a 110-μm-pixel detector with a higher signal-to-noise ratio. The proposed method could be a way to increase spatial resolution without a pixel redesign when pixels severely suffer from charge sharing as pixel size is reduced.

  15. Photoluminescence of CdTe nanocrystals grown by pulsed laser ablation on a template of Si nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Guillen-Cervantes, A.; Silva-Lopez, H.; Becerril-Silva, M.; Arias-Ceron, J.S.; Campos-Gonzalez, E.; Zelaya-Angel, O. [CINVESTAV-IPN, Physics Department, Apdo. Postal 14-740, Mexico (Mexico); Medina-Torres, A.C. [Escuela Superior de Fisica y Matematicas del IPN, Mexico (Mexico)

    2014-11-12

    CdTe nanocrystals were grown on eroded Si (111) substrates at room temperature by pulsed laser ablation. Before growth, Si substrates were subjected to different erosion time in order to investigate the effect on the CdTe samples. The erosion process consists of exposition to a pulsed high-voltage electric arc. The surface consequence of the erosion process consists of Si nanoparticles which acted as a template for the growth of CdTe nanocrystals. CdTe samples were studied by X-ray diffraction (XRD), room temperature photoluminescence (RT PL) and high-resolution transmission electron microscopy (HRTEM). CdTe nanocrystals grew in the stable cubic phase, according to XRD spectra. A strong visible emission was detected in photoluminescence (PL) experiments. The PL signal was centered at 540 nm (∝2.34 eV). With the effective mass approximation, the size of the CdTe crystals was estimated around 3.5 nm. HRTEM images corroborated the physical characteristics of CdTe nanocrystals. These results could be useful for the development of CdTe optoelectronic devices. (orig.)

  16. Calorimetric low-temperature detectors on semiconductor base for the energy-resolving detection of heavy ions

    International Nuclear Information System (INIS)

    Kienlin, A. von.

    1994-01-01

    In the framework of this thesis for the first time calorimetric low-temperature detectors for the energy-resolving detection of heavy ions were developed and successfully applied. Constructed were two different detector types, which work both with a semiconductor thermistor. The temperature increasement effected by a particle incidence is read out. In the first detector type the thermistor was simutaneously used as absorber. The thickness of the germanium crystals was sufficient in order to stop the studied heavy ions completely. In the second type, a composed calorimeter, a sapphire crystal, which was glued on a germanium thermistor, served as absorber for the incident heavy ions. The working point of the calorimeter lies in the temperature range (1.2-4.2 K), which is reachable with a pumped 4 He cryostat. The temperatur increasement of the calorimeter amounts after the incidence of a single α particle about 20-30 μK and that after a heavy ion incidence up to some mK. An absolute energy resolution of 400-500 keV was reached. In nine beam times the calorimeters were irradiated by heavy ions ( 20 Ne, 40 Ar, 136 Xe, 208 Pb, 209 Bi) of different energies (3.6 MeV/nucleon< E<12.5 MeV/nucleon) elastically scattered from gold foils. In the pulse height spectra of the first detector type relatively broad, complex-structurated line shapes were observed. By systematic measurements dependences of the complex line structures on operational parameters of the detector, the detector temperature, and the position of the incident particle could be detected. Together with the results of further experiments a possible interpretation of these phenomena is presented. Contrarily to the complex line structures of the pure germanium thermistor the line shapes in the pulse height spectra, which were taken up in a composite germanium/sapphire calorimeter, are narrow and Gauss-shaped

  17. 2011 ATLAS Detector Performance - ID and Forward detectors

    CERN Document Server

    Davies‎, E; The ATLAS collaboration; Abdel Khalek, S

    2012-01-01

    This poster describes the performance of 2 parts of ATLAS: - The Inner Detector which consists of 3 subdetectors: the Pixel detector, the SemiConductor Tracker (or SCT) and the Transition Radiation Tracker (or TRT). Here, we report on Pixel detector and SCT performance over 2011. - ALFA detector which will determine the absolute luminosity of the CERN LHC at the ATLAS Interaction Point (IP), and the total proton-proton cross section, by tracking elastically scattered protons at very small angles in the limit of the Coulomb Nuclear interference region.

  18. Electrodeposición de películas delgadas de CdTe sobre electrodo de oro en soluciones acuosas de EDTA-Amonio

    OpenAIRE

    Montilla, Milagro; Alarcón, Domingo; Ortiz, Reynaldo

    2007-01-01

    En este trabajo se muestran los resultados obtenidos del estudio del crecimiento electroquímico y caracterización de películas delgadas del semiconductor CdTe. El crecimiento se realizó mediante la electrodeposición catódica a potencial constante a partir de soluciones acuosas alcalinas de las especies precursoras TeO3(2-) y Cd2+ y EDTA como agente acomplejante para el Cd2+. La composición de las películas se determinó por espectroscopía de emisión atómica con plasma inductivamente acoplado (...

  19. TFTR alpha extraction and measurement: Development and testing of advanced alpha detectors: Final report

    International Nuclear Information System (INIS)

    Wehring, B.W.

    1988-01-01

    Advanced alpha-particle detectors made of heavy elements were investigated as alternatives to silicon surface-barrier detectors for the ''foil-neutralization technique'' of alpha-particle diagnostics in fusion reactors with high neutron backgrounds. From an extensive literature review, it was decided that HgI 2 would make a more suitable detector for alpha-particle diagnostics than other heavy element detectors such as CdTe. Thus, HgI 2 detectors were designed and fabricated. Experimental tests were performed to determine detector characteristics and detector responses to alpha particles. Radiation noise measurements were also performed using the North Carolina State University PULSTAR nuclear reactor for both the HgI 2 detectors and commercial Si(Au) surface barrier detectors. 15 refs., 1 fig

  20. Fast-timing methods for semiconductor detectors

    International Nuclear Information System (INIS)

    Spieler, H.

    1982-03-01

    The basic parameters are discussed which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter