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Sample records for area hybrid photodiodes

  1. Test of DEP hybrid photodiodes

    SciTech Connect

    Baumbaugh, A.; Binkley, M.; Elias, J.

    1997-08-01

    The goal of the measurement was to study some parameters of DEP HYBRID PHOTODIODES (HPD), and the check its performance for CMS calorimetry at LHC. The principal of the HPD operation is described. The schematic view of the HPD. The HPD is vacuum photo device composed of photocathode (PC) and a silicon PIN diode (Si) as multiplication system in a very close proximity geometry. The distance between PC and Si is of the order of several mm and has an electric field < 10 kV. The photoelectron emited by the photocathode multiply by a factor of several thousand in the silicon and the charge is collected on the HPD`s anode. Several types of HPD`s were tested. There was a single channel HPD, called {open_quotes}E-type{close_quotes} with p-side of the silicon facing the HPD`s photocathode and two multipixel HPD (DEP) namely a 25 pixel HPD and a 7 pixel HPD. Both were of {open_quotes}T-type{close_quotes} structure with n-side of silicon facing the photocathode.

  2. A hybrid solid-liquid polymer photodiode for the bioenvironment

    NASA Astrophysics Data System (ADS)

    Antognazza, M. R.; Ghezzi, D.; Musitelli, D.; Garbugli, M.; Lanzani, G.

    2009-06-01

    We demonstrate that a prototypical semiconducting polymer, poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) maintains unaltered its optoelectronic properties throughout the various steps for neural preparation. Films of MEH-PPV, after prolonged immersion in water or buffer solution, are characterized by linear and nonlinear optical spectroscopy. Based on this result, we introduce a hybrid solid-liquid photodiode based on MEH-PPV, in which we use culturing media as liquid, ionic cathodes. The hybrid device is proposed as an active interface between living tissue and conducting polymers for cell diagnostic and neural implants.

  3. Hybrid UV Imager Containing Face-Up AlGaN/GaN Photodiodes

    NASA Technical Reports Server (NTRS)

    Zheng, Xinyu; Pain, Bedabrata

    2005-01-01

    A proposed hybrid ultraviolet (UV) image sensor would comprise a planar membrane array of face-up AlGaN/GaN photodiodes integrated with a complementary metal oxide/semiconductor (CMOS) readout-circuit chip. Each pixel in the hybrid image sensor would contain a UV photodiode on the AlGaN/GaN membrane, metal oxide/semiconductor field-effect transistor (MOSFET) readout circuitry on the CMOS chip underneath the photodiode, and a metal via connection between the photodiode and the readout circuitry (see figure). The proposed sensor design would offer all the advantages of comparable prior CMOS active-pixel sensors and AlGaN UV detectors while overcoming some of the limitations of prior (AlGaN/sapphire)/CMOS hybrid image sensors that have been designed and fabricated according to the methodology of flip-chip integration. AlGaN is a nearly ideal UV-detector material because its bandgap is wide and adjustable and it offers the potential to attain extremely low dark current. Integration of AlGaN with CMOS is necessary because at present there are no practical means of realizing readout circuitry in the AlGaN/GaN material system, whereas the means of realizing readout circuitry in CMOS are well established. In one variant of the flip-chip approach to integration, an AlGaN chip on a sapphire substrate is inverted (flipped) and then bump-bonded to a CMOS readout circuit chip; this variant results in poor quantum efficiency. In another variant of the flip-chip approach, an AlGaN chip on a crystalline AlN substrate would be bonded to a CMOS readout circuit chip; this variant is expected to result in narrow spectral response, which would be undesirable in many applications. Two other major disadvantages of flip-chip integration are large pixel size (a consequence of the need to devote sufficient area to each bump bond) and severe restriction on the photodetector structure. The membrane array of AlGaN/GaN photodiodes and the CMOS readout circuit for the proposed image sensor would

  4. A novel photodiode made of hybrid organic/inorganic nanocomposite

    NASA Astrophysics Data System (ADS)

    Mahmoud, Waleed E.

    2009-08-01

    Novel hybrid organic/inorganic nanocomposites made of metal oxide and conjugated polymer nanocomposite and its application in bulk-heterojunction solar cells were studied. The composite was composed of different concentrations of strontium titanate (SrTiO3) and polyaniline doped phosphoric acid. The optimum concentration of strontium titanate was found to be 0.2 v/v. An inorganic-organic photovoltaic device with a structure of Ag/Pani-H3PO4-SrTiO3/Al has been fabricated. The ideality factor value of the diode was found to be 1.8. This n value of the diode implies a deviation from ideal junction behaviour. The barrier height phib value for the diode was found to be 0.56 eV. The Ag/Pani-H3PO4-SrTiO3/Al diode shows a photovoltaic behaviour with a maximum open-circuit voltage Voc of 2.49 V, and short-circuit current Isc of 5.6 mA under light illumination λ = 460 nm. The conversion efficiency was found to be 5.2%. It is evaluated that the Ag/Pani-H3PO4-SrTiO3/Al diode is a good photodiode with calculated electronic parameters.

  5. Using Photodiodes in the Laboratory.

    ERIC Educational Resources Information Center

    Jenkins, T. E.

    1995-01-01

    Describes the most popular optical detector in the design of photodiode detector circuits. Discusses how a photodiode works, points to consider in the design of a photodiode, and photodiode hybrids. (AIM)

  6. A slot-scanned photodiode-array/CCD hybrid detector for digital mammography.

    PubMed

    Mainprize, James G; Ford, Nancy L; Yin, Shi; Tümer, Türmay; Yaffe, Martin J

    2002-02-01

    We have developed a novel direct conversion detector for use in a slot-scanning digital mammography system. The slot-scan concept allows for dose efficient scatter rejection and the ability to use small detectors to produce a large-area image. The detector is a hybrid design with a 1.0 mm thick silicon PIN photodiode array (the x-ray absorber) indium-bump bonded to a CCD readout that is operated in time-delay integration (TDI) mode. Because the charge capacity requirement for good image quality exceeds the capabilities of standard CCDs, a novel CCD was developed. This CCD consists of 24 independent sections, each acting as a miniature CCD with eight rows for TDI. The signal from each section is combined off-chip to produce a full signal image. The MTF and DQE for the device was measured at several exposures and compared to a linear systems model of signal and noise propagation. Because of the scanning nature of TDI imaging, both the MTF(f) and DQE(f) are reduced along the direction of the scanning motion. For a 26 kVp spectrum, the DQE(0) was measured to be 0.75+/-0.02 for an exposure of 1.29 x 10(-5) C/kg (50 mR). PMID:11865992

  7. Hybridization process for back-illuminated silicon Geiger-mode avalanche photodiode arrays

    NASA Astrophysics Data System (ADS)

    Schuette, Daniel R.; Westhoff, Richard C.; Loomis, Andrew H.; Young, Douglas J.; Ciampi, Joseph S.; Aull, Brian F.; Reich, Robert K.

    2010-04-01

    We present a unique hybridization process that permits high-performance back-illuminated silicon Geiger-mode avalanche photodiodes (GM-APDs) to be bonded to custom CMOS readout integrated circuits (ROICs) - a hybridization approach that enables independent optimization of the GM-APD arrays and the ROICs. The process includes oxide bonding of silicon GM-APD arrays to a transparent support substrate followed by indium bump bonding of this layer to a signal-processing ROIC. This hybrid detector approach can be used to fabricate imagers with high-fill-factor pixels and enhanced quantum efficiency in the near infrared as well as large-pixel-count, small-pixel-pitch arrays with pixel-level signal processing. In addition, the oxide bonding is compatible with high-temperature processing steps that can be used to lower dark current and improve optical response in the ultraviolet.

  8. Results of hybrid photodiode irradiation by 200 MeV protons

    SciTech Connect

    Baumbaugh A. et al.

    2001-12-03

    Hybrid Photodiodes (HPD, [1]) will be used as the photodetector for the Compact Muon Solenoid (CMS) Hadron Calorimeter (HCAL) readout [2]. The HPDs are required to operate in a high radiation environment, where the HCAL detector will receive a total ionizing dose of about 330 rads and a fluence of 4 x 10{sup 11} n/cm{sup 2} over a 10 year running period [3]. Effects of HPD irradiation by low energy neutrons were studied and reported previously [1]. In these studies, high energy protons are used to study possible effects of single event burnout [4], since high energy protons are more likely to induce large energy transfer within the HPD silicon. The HPDs were irradiated by 200 MeV protons at the Indiana University Cyclotron Facility [IUCF, 5]. The results of the study are presented.

  9. Performance evaluation of new large-area avalanche photodiodes for scintillation spectroscopy

    NASA Astrophysics Data System (ADS)

    James, K. M.; Masterson, M. J.; Farrell, R.

    Avalanche photodiodes (APD's) appear promising for certain applications as a solid state replacement for the photomultiplier tube. The increase in leakage current and capacitance noise with device active area has in the past kept the size of commercially available devices to less than 1 mm (exp 2). Recent advances in fabrication technology have, however, resulted in relatively low noise devices of up to 1 inch in diameter. We have recently evaluated the performance as scintillation spectroscopy detectors of two commercial large area avalanche photodiodes. These APD's exhibit exceptional performance: at 662 KeV a 1 inch diameter device coupled to a CsI(Tl) scintillator and operating at room temperature yielded 6.9 pct. resolution and a 1 cm device coupled to CsI(Tl) and cooled to 260 K gave 4.4 pct. resolution, which is believed to be the best resolution ever recorded for a scintillation spectrometer.

  10. Three-element trap filter radiometer based on large active area silicon photodiodes.

    PubMed

    Salim, S G R; Anhalt, K; Taubert, D R; Hollandt, J

    2016-05-20

    This paper shows the opto-mechanical design of a new filter radiometer built at the Physikalisch-Technische Bundesanstalt, Germany, for the accurate determination of the thermodynamic temperature of high-temperature blackbodies. The filter radiometer is based on a three-element reflection-type trap detector that uses three large active area silicon photodiodes. Its spectral coverage and field of view are defined by a detachable narrow-band filter and a diamond-turned precision aperture, respectively. The temperature of the filter radiometer is stabilized using a water-streamed housing and is measured using a thin-film platinum thermometer placed onto the first photodiode element. The trap "mount" has been made as compact as possible, which, together with the large active area of the chosen photodiodes, allows a wide field of view. This work presents the design of the filter radiometer and discusses the criteria that have been considered in order for the filter radiometer to suit the application. PMID:27411121

  11. ZnO(N)-Spiro-MeOTAD hybrid photodiode: an efficient self-powered fast-response UV (visible) photosensor.

    PubMed

    Game, Onkar; Singh, Upendra; Kumari, Tanya; Banpurkar, Arun; Ogale, Satishchandra

    2014-01-01

    Organic-inorganic hybrid photo-detectors with a self-sufficient mode of operation represent a research area of great current interest. In most efficient photodetectors and optoelectronic devices compound semiconductors containing toxic elements such as Cd, As, Te, S, Se etc. are used and these are also expensive. Hence there is also a rapidly growing interest in replacing these with environmentally friendly and earth-abundant materials. Herein, we report a facile solution-processed fabrication of a self-powered organic-inorganic hybrid photodetector using n-type oriented ZnO nanorods and p-type Spiro-MeOTAD semiconductor. ZnO is eco-friendly and earth-abundant, and Spiro-MeOTAD is non-hazardous. We show that the latter has far less toxicity than the toxic elements stated above. This visible blind UV photodetector shows high sensitivity (10(2)) and a UV/visible rejection ratio of 300. It also exhibits fast response times of τ(rise) ~ 200 μs and τ(fall) ~ 950 μs. Importantly, with a small modification of nitrogen incorporation in ZnO one can also realize a highly-sensitive self-powered visible light photodetector with at least 1000% (or higher) improvements in quality factors (photocurrent/sensitivity/response time) as compared to previously reported organic-inorganic hybrid photo-detectors based on metal-chalcogenides (CdS-PANI or CuInSe2-P3HT). Interestingly, the broadband sensitivity of such N:ZnO-Spiro-MeOTAD photodiode enables sensing of low intensity (~28 μW cm(-2)) ambient white light with a high photocurrent density of 120 nA cm(-2) making it an efficient ambient white light detector. PMID:24232600

  12. A 10Gb/s transimpedance amplifier for hybrid integration of a Ge PIN waveguide photodiode

    NASA Astrophysics Data System (ADS)

    Polzer, A.; Gaberl, W.; Swoboda, R.; Zimmermann, H.; Fedeli, J.-M.; Vivien, L.

    2010-05-01

    The presented paper describes a 10 Gbps optical receiver. The transimpedance amplifier (TIA) is realized in standard 0.35 μm SiGe BiCMOS technology. The main novelty of the presented design - investigated in the European Community project HELIOS - is the hybrid connection of the optical detector. The used Germanium photodetector will be directly mounted onto the receiver. A model of the relevant parasitics of the photodetector itself and the novel connection elements (micropads, metal vias and metal lines) is described. Based on this photodetector model an optical receiver circuit was optimized for maximum sensitivity at data rates in the range of 10 Gbps. The design combines a TIA and two limiting amplifier stages followed by a 50 Ω CML-style logic-level output driver. To minimize power supply noise and substrate noise, a fully differential design is used. A dummy TIA provides a symmetrical input signal reference and a control loop is used to compensate the offset levels. The TIA is built around a common-emitter stage and features a feedback resistor of 4.2 Ω. The total transimpedance of the complete receiver chain is in the range of 275 kΩ. The value of the active feedback resistor can be reduced via an external control voltage to adapt the design to different overall gain requirements. The two limiting amplifier stages are realized as differential amplifiers with voltage followers. The output buffer is implemented with cascode differential amplifiers. The output buffer is capable of driving a differential 50Ω output with a calculated output swing of 800mVp-p. Simulations show an overall bandwidth of 7.2 GHz. The lower cutoff frequency is below 60 kHz. The equivalent input noise current is 408 nA. With an estimated total photodiode responsivity of 0.5 A/W this allows a sensitivity of around - 23.1 dBm (BER = 10-9). The device operates from a single 3.3 V power supply and the TIAs and the limiting amplifier consume 32 mA.

  13. ZnO(N)-Spiro-MeOTAD hybrid photodiode: an efficient self-powered fast-response UV (visible) photosensor

    NASA Astrophysics Data System (ADS)

    Game, Onkar; Singh, Upendra; Kumari, Tanya; Banpurkar, Arun; Ogale, Satishchandra

    2013-12-01

    Organic-inorganic hybrid photo-detectors with a self-sufficient mode of operation represent a research area of great current interest. In most efficient photodetectors and optoelectronic devices compound semiconductors containing toxic elements such as Cd, As, Te, S, Se etc. are used and these are also expensive. Hence there is also a rapidly growing interest in replacing these with environmentally friendly and earth-abundant materials. Herein, we report a facile solution-processed fabrication of a self-powered organic-inorganic hybrid photodetector using n-type oriented ZnO nanorods and p-type Spiro-MeOTAD semiconductor. ZnO is eco-friendly and earth-abundant, and Spiro-MeOTAD is non-hazardous. We show that the latter has far less toxicity than the toxic elements stated above. This visible blind UV photodetector shows high sensitivity (102) and a UV/visible rejection ratio of 300. It also exhibits fast response times of τrise ~ 200 μs and τfall ~ 950 μs. Importantly, with a small modification of nitrogen incorporation in ZnO one can also realize a highly-sensitive self-powered visible light photodetector with at least 1000% (or higher) improvements in quality factors (photocurrent/sensitivity/response time) as compared to previously reported organic-inorganic hybrid photo-detectors based on metal-chalcogenides (CdS-PANI or CuInSe2-P3HT). Interestingly, the broadband sensitivity of such N:ZnO-Spiro-MeOTAD photodiode enables sensing of low intensity (~28 μW cm-2) ambient white light with a high photocurrent density of 120 nA cm-2 making it an efficient ambient white light detector.Organic-inorganic hybrid photo-detectors with a self-sufficient mode of operation represent a research area of great current interest. In most efficient photodetectors and optoelectronic devices compound semiconductors containing toxic elements such as Cd, As, Te, S, Se etc. are used and these are also expensive. Hence there is also a rapidly growing interest in replacing these with

  14. Organic-inorganic hybrid inverted photodiode with planar heterojunction for achieving low dark current and high detectivity

    NASA Astrophysics Data System (ADS)

    Ha, JaeUn; Yoon, Seongwon; Lee, Jong-Soo; Chung, Dae Sung

    2016-03-01

    In this study, the strategy of using an organic-inorganic hybrid planar heterojunction consisting of polymeric semiconductors and inorganic nanocrystals is introduced to realize a high-performance hybrid photodiode (HPD) with low dark current and high detectivity. To prevent undesired charge injection under the reverse bias condition, which is the major dark current source of the photodiode, a well-defined planar heterojunction is strategically constructed via smart solution process techniques. The optimized HPD renders a low dark current of ˜10-5 mA cm-2 at -5 V and ˜10-6 mA cm-2 at -1 V, as well as a high detectivity ˜1012 Jones across the entire visible wavelength range. Furthermore, excellent photocurrent stability is demonstrated under continuous light exposure. We believe that the solution-processed planar heterojunction with inverted structure can be an attractive alternative diode structure for fabricating high-performance HPDs, which usually suffer from high dark current issues.

  15. Response of large area avalanche photodiodes to low energy x rays

    SciTech Connect

    Gentile, T. R.; Bales, M.; Arp, U.; Dong, B.; Farrell, R.

    2012-05-15

    For an experiment to study neutron radiative beta-decay, we operated large area avalanche photodiodes (APDs) near liquid nitrogen temperature to detect x rays with energies between 0.2 keV and 20 keV. Whereas there are numerous reports of x ray spectrometry using APDs at energies above 1 keV, operation near liquid nitrogen temperature allowed us to reach a nominal threshold of 0.1 keV. However, due to the short penetration depth of x rays below 1 keV, the pulse height spectrum of the APD become complex. We studied the response using monochromatic x ray beams and employed phenomenological fits of the pulse height spectrum to model the measurement of a continuum spectrum from a synchrotron. In addition, the measured pulse height spectrum was modelled using a profile for the variation in efficiency of collection of photoelectrons with depth into the APD. The best results are obtained with the collection efficiency model.

  16. Low-Noise Large-Area Photoreceivers with Low Capacitance Photodiodes

    NASA Technical Reports Server (NTRS)

    Joshi, Abhay M. (Inventor); Datta, Shubhashish (Inventor)

    2013-01-01

    A quad photoreceiver includes a low capacitance quad InGaAs p-i-n photodiode structure formed on an InP (100) substrate. The photodiode includes a substrate providing a buffer layer having a metal contact on its bottom portion serving as a common cathode for receiving a bias voltage, and successive layers deposited on its top portion, the first layer being drift layer, the second being an absorption layer, the third being a cap layer divided into four quarter pie shaped sections spaced apart, with metal contacts being deposited on outermost top portions of each section to provide output terminals, the top portions being active regions for detecting light. Four transimpedance amplifiers have input terminals electrically connected to individual output terminals of each p-i-n photodiode.

  17. Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid; Herrero, Federico A.; Sigwarth, John; Goldsman, Neil; Akturk, Akin

    2010-01-01

    The proposed device is capable of counting ultraviolet (UV) photons, is compatible for inclusion into space instruments, and has applications as deep- UV detectors for calibration systems, curing systems, and crack detection. The device is based on a Separate Absorption and Charge Multiplication (SACM) structure. It is based on aluminum gallium nitride (AlGaN) absorber on a silicon carbide APD (avalanche photodiode). The AlGaN layer absorbs incident UV photons and injects photogenerated carriers into an underlying SiC APD that is operated in Geiger mode and provides current multiplication via avalanche breakdown. The solid-state detector is capable of sensing 100-to-365-nanometer wavelength radiation at a flux level as low as 6 photons/pixel/s. Advantages include, visible-light blindness, operation in harsh environments (e.g., high temperatures), deep-UV detection response, high gain, and Geiger mode operation at low voltage. Furthermore, the device can also be designed in array formats, e.g., linear arrays or 2D arrays (micropixels inside a superpixel).

  18. Large-area avalanche photodiodes for the detection of soft x rays

    SciTech Connect

    Gullikson, E.M.; Gramsch, E. |; Szawlowski, M.

    1995-08-01

    The charge-collection efficiency of beveled-edge-type silicon avalanche photodiodes has been determined for soft x rays in the 50--300-eV range. An efficiency of greater than 80% is measured for energies below the Si {ital L} absorption edge. The measured efficiency is well described by a model that accounts for absorption in an oxide overlayer and recombination at the front surface of the diode. The avalanche photodiodes are shown to be significantly more sensitive compared with other detectors for pulsed sources such as a laser-produced plasma source. These results are also very encouraging for soft-x-ray/extreme-UV applications involving synchrotron radiation.{ital PACS} {ital numbers}: 29.40.Wk, 07.85.+n, 85.60.Dw.

  19. Hybrid photomultiplier tube and photodiode parallel detection array for wideband optical spectroscopy of the breast guided by magnetic resonance imaging

    PubMed Central

    Mastanduno, Michael A.; Jiang, Shudong; Pogue, Brian W.; Paulsen, Keith D.

    2013-01-01

    Abstract. A new optical parallel detection system of hybrid frequency and continuous-wave domains was developed to improve the data quality and accuracy in recovery of all breast optical properties. This new system was deployed in a previously existing system for magnetic resonance imaging (MRI)-guided spectroscopy, and allows incorporation of additional near-infrared wavelengths beyond 850 nm, with interlaced channels of photomultiplier tubes (PMTs) and silicon photodiodes (PDs). The acquisition time for obtaining frequency-domain data at six wavelengths (660, 735, 785, 808, 826, and 849 nm) and continuous-wave data at three wavelengths (903, 912, and 948 nm) is 12 min. The dynamic ranges of the detected signal are 105 and 106 for PMT and PD detectors, respectively. Compared to the previous detection system, the SNR ratio of frequency-domain detection was improved by nearly 103 through the addition of an RF amplifier and the utilization of programmable gain. The current system is being utilized in a clinical trial imaging suspected breast cancer tumors as detected by contrast MRI scans. PMID:23979460

  20. Hybrid photomultiplier tube and photodiode parallel detection array for wideband optical spectroscopy of the breast guided by magnetic resonance imaging.

    PubMed

    El-Ghussein, Fadi; Mastanduno, Michael A; Jiang, Shudong; Pogue, Brian W; Paulsen, Keith D

    2014-01-01

    A new optical parallel detection system of hybrid frequency and continuous-wave domains was developed to improve the data quality and accuracy in recovery of all breast optical properties. This new system was deployed in a previously existing system for magnetic resonance imaging (MRI)-guided spectroscopy, and allows incorporation of additional near-infrared wavelengths beyond 850 nm, with interlaced channels of photomultiplier tubes (PMTs) and silicon photodiodes (PDs). The acquisition time for obtaining frequency-domain data at six wavelengths (660, 735, 785, 808, 826, and 849 nm) and continuous-wave data at three wavelengths (903, 912, and 948 nm) is 12 min. The dynamic ranges of the detected signal are 105 and 106 for PMT and PD detectors, respectively. Compared to the previous detection system, the SNR ratio of frequency-domain detection was improved by nearly 103 through the addition of an RF amplifier and the utilization of programmable gain. The current system is being utilized in a clinical trial imaging suspected breast cancer tumors as detected by contrast MRI scans. PMID:23979460

  1. Hybrid photodiode tube

    SciTech Connect

    Desalvo, R.

    1992-12-31

    A new kind of light detector is needed for the spaghetti calorimeter capable of covering a span of a least 4 order of magnitude of linearity. Here, the authors report the first test results on a new breed of light detector based on a photocathode followed by a silicon diode working in the bombarding mode.

  2. I-V and noise performance in MWIR to VLWIR large area Hg1-xCdxTe photodiodes

    NASA Astrophysics Data System (ADS)

    D'Souza, A. I.; Stapelbroek, M. G.; Dolan, P. N.; Wijewarnasuriya, P. S.; Boehmer, E.; Smith, D. S.; Ehlert, J. C.; Andrews, J. E.

    2005-05-01

    The National Polar-orbiting Operational Environmental Satellite System (NPOESS), is overseen by the Integrated Program Office (IPO), a joint effort of the Department of Defense, Department of Commerce and NASA. One of the instruments on the NPOESS satellite is the Cross-track Infrared Sounder (CrIS) instrument. CrIS is a Fourier Transform interferometric infrared (FTIR) sensor used to measure earth radiance at high spectral resolution to derive pressure, temperature, and moisture profiles of the atmosphere from the ground on up. Each CrIS instrument contains three different cutoff wavelength (λc)focal plane modules (FPMs): an SWIR FPM [λc(98 K) ~ 5 mm], MWIR FPM [λc(98 K) ~ 9 mm] and a LWIR FPM [λc(81 K) ~ 15.5 mm]. There are nine large (850 mm diameter) photodiodes per FPM, the nine detectors being arranged in a 3 x 3 array. The nine detectors are placed under tight tolerances in the X, Y, and Z dimensions. The steps involved in the transfer of photodiodes as part of a newly fabricated wafer to the mounting of the photodiodes on the FPM involves many processing steps including a significant amount of dicing, cleaning, wire bonding and baking at elevated temperatures. Quantum efficiency and 1/f noise in Hg1-xCdxTe photodiodes are critical parameters that limit the sensitivity of infrared sounders. The ratio α, defined as the noise current in unit bandwidth in(f = 1 Hz, Vd, Δf = 1 Hz) to the dark current Id(Vd), that is, α = in/Id is one of the parameters used to select photodiodes for placement in FPMs. α is equivalent to √αH/N that appears in the well-known Hooge expression. For the sixty-one, λc ~ 9 μm photodiodes measured at 60 mV reverse bias and at 98 K, the average value of αdark = 1.3 x 10-4 in the dark and αPHOTO = in/IPHOTO is ~ 2 x 10-6 under illuminated conditions. These values of α are a factor of two lower than that reported previously. The λc ~ 15.5 μm photodiodes have average αdark = 1.3 x 10-5 with the highest performance

  3. Application of pulsed UV laser for dicing of arrays and linear of photodiodes based on MCT solid solution

    NASA Astrophysics Data System (ADS)

    Novoselov, A. R.; Klimenko, A. G.; Vasilyev, V. V.

    2007-05-01

    The modern systems of vision in infrared spectrum (IR) require elaboration of large-area nondefective imaging area with small pitch (less 40 μm) IR FPA. One of the directions is fabrication hybrid FPA, consisting of several of arrays of photodiodes based on MCT films (Hg xCd 1-xTe on GaAs substrates) and readout circuits on silicon. Substitution of photodiodes array of large-area imaging area on few arrays of smaller image size, allows having the imaging area of the required size without fault pixels. The main requirement is the permanent period of photodetectors on component imaging areas. without loss of pixels on lines of gaps of the butting between arrays. Using concentrated laser radiation, for scribing the surfaces MCT film on GaAs substrate, under concrete conditions, allows to realize offered above direction. The determination of the border of zone of the influence of the laser radiation on electric characteristic of p-n junction of the MCT films and technological ways of the reduction of area of influence of the laser radiation are presented in work. We had studied the change of parameters of photodiodes on base MCT films depending on distances before laser dicing grooves and condition of the laser radiation. As source of the laser radiation we used pulsed UV laser (LGI-21) at 0,34 μm wavelength with pulse duration 7 ns, frequency of repetition 50 - 100 Hz and power in pulse 2 KW. We founded condition of the laser dicing on distances 18 - 20 μm from photodiodes, when initial current-voltage characteristics of photodiodes are saved. We designed method of the laser dicing of linear photodiodes on MCT films, and we used it to create of multichips hybrid IR FPA. The result is non damage dicing of linear photodiodes on MCT films (λ c =12 μm) on distances 18 - 20 μm from p-n junctions.

  4. Self-aligned two-layer metallization with low series resistance for litho-less contacting of large-area photodiodes

    NASA Astrophysics Data System (ADS)

    Mok, K. R. C.; Qi, L.; Vlooswijk, A. H. G.; Nanver, L. K.

    2015-09-01

    In this work, a double-layer Al metallization scheme for large-area photodiodes is presented. This scheme combines a self-alignment of two separate layers of sputtered Al with an anodic Al2O3 as the intermediate insulating layer. One initial patterning step, that could be performed litho-less by for example laser ablation, was needed to define and etch cavities. The cavities provided two Si levels, each of which was contacted by one of the metal layers. Measurement results of test structures showed the effectiveness of this metallization scheme. Despite being partially anodized, the underlying Al layer remained a good conducting layer, with normal low-ohmic behavior. The anodized Al2O3 layer itself acted as a good insulating layer and the two metal layers were not shorted. Furthermore, the characteristics of diodes formed in the textured cavity were as ideal as the planar counterparts. The large two-dimensional coverage of both the anode and cathode by separate metal layers is a promising configuration for low series resistance. Moreover, all steps involved are available on standard integrated circuit (IC) processing equipment, and Al is an abundant cheap metal, making this a very low-cost method of fabricating contacts to large-area devices.

  5. Gallium-based avalanche photodiode optical crosstalk

    NASA Astrophysics Data System (ADS)

    Blazej, Josef; Prochazka, Ivan; Hamal, Karel; Sopko, Bruno; Chren, Dominik

    2006-11-01

    Solid-state single photon detectors based on avalanche photodiode are getting more attention in various areas of applied physics: optical sensors, quantum key distribution, optical ranging and Lidar, time-resolved spectroscopy, X-ray laser diagnostics, and turbid media imaging. Avalanche photodiodes specifically designed for single photon counting semiconductor avalanche structures have been developed on the basis of various materials: Si, Ge, GaP, GaAsP, and InGaP/InGaAs at the Czech Technical University in Prague during the last 20 years. They have been tailored for numerous applications. Trends in demand are focused on detection array construction recently. Even extremely small arrays containing a few cells are of great importance for users. Electrical crosstalk between individual gating and quenching circuits and optical crosstalk between individual detecting cells are serious limitation for array design and performance. Optical crosstalk is caused by the parasitic light emission of the avalanche which accompanies the photon detection process. We have studied in detail the optical emission of the avalanche photon counting structure in the silicon- and gallium-based photodiodes. The timing properties and spectral distribution of the emitted light have been measured for different operating conditions to quantify optical crosstalk. We conclude that optical crosstalk is an inherent property of avalanche photodiode operated in Geiger mode. The only way to minimize optical crosstalk in avalanche photodiode array is to build active quenching circuit with minimum response time.

  6. Interface Trap States in Organic Photodiodes

    PubMed Central

    Arca, Francesco; Tedde, Sandro F.; Sramek, Maria; Rauh, Julia; Lugli, Paolo; Hayden, Oliver

    2013-01-01

    Organic semiconductors are attractive for optical sensing applications due to the effortless processing on large active area of several cm2, which is difficult to achieve with solid-state devices. However, compared to silicon photodiodes, sensitivity and dynamic behavior remain a major challenge with organic sensors. Here, we show that charge trapping phenomena deteriorate the bandwidth of organic photodiodes (OPDs) to a few Hz at low-light levels. We demonstrate that, despite the large OPD capacitances of ~10 nF cm−2, a frequency response in the kHz regime can be achieved at light levels as low as 20 nW cm−2 by appropriate interface engineering, which corresponds to a 1000-fold increase compared to state-of-the-art OPDs. Such device characteristics indicate that large active area OPDs are suitable for industrial sensing and even match medical requirements for single X-ray pulse detection in the millisecond range. PMID:23429565

  7. Experimental study on photodiode damage by millisecond pulse laser irradiation

    NASA Astrophysics Data System (ADS)

    Wei, Zhi; Jin, Guangyong; Tan, Yong; Wang, Di

    2015-10-01

    The photoelectric detector is a very significance part in laser and its application system, but when photoelectric detector irradiated by high energy laser, the laser may cause thermal damage to the photoelectric detector, when the temperature more than its melting point and vaporization point, there will be a permanent damage in PIN photodetector, leading to the failure of photoelectric detector. In order to study the photodiode damage mechanism by millisecond pulse laser irradiation, a set of experimental system has been built, choosing appropriate pulsed laser parameters to irradiate silicon-based PIN photodiode and monitoring the surface temperature in the process of irradiation, until the PIN photodiode complete failure. The measurement results of real-time temperature, responsivity change and damage morphology were analyzed to conclude the failure reason of the PIN photodiode. The results showed that with the increase of laser energy, the PIN photodiode surface temperature would be also increased accordingly. Before the laser irradiation, the responsivity of PIN photodiode was the same. But after the laser irradiation, the responsivity of the PIN photodiode would be changed and with the increase of laser energy, the decline extent of responsivity would be also increased. Judging from the ablation, crack and fold zone on the surface of PIN photodiode after the laser irradiation, the damage was for thermal stress effect. The continuity of material confined its free expansion. Therefore, the uneven thermal expansion induced the great thermal stress. At the same time, the silicon transited from brittle to ductile and the yield strength dramatically decreased. Once the maximum thermal stress exceeded the critical stress, the plastic deformation and the brittle cracks of silicon would be generated. With the increase of laser energy, the thermal stress damage extent of PIN photodiode would be also increased accordingly and the black area of laser ablation would be

  8. Study of EUV and x-ray radiation hardness of silicon photodiodes

    NASA Astrophysics Data System (ADS)

    Zabrodsky, Vladimir V.; Aruev, Pavel; Filimonov, Vladimir V.; Sobolev, Nikolay A.; Sherstnev, Evgeniy V.; Belik, Viktor P.; Nikolenko, Anton D.; Ivlyushkin, Denis V.; Pindyurin, Valery F.; Shadrin, Nikita S.; Soldatov, Artem E.; Mashkovtsev, Mikhail R.

    2013-05-01

    This work presents the results of long-term observation of the silicon photodiodes spatial profile response and the silicon photodiodes dark current after their exposure to 10.2 eV quanta and in the spectral range of 150-300 eV. Exposure of the photodiodes to quanta of an energy of 10.2 eV was repeated. Several other photodiodes have been irradiated in the spectral range of 700-1800 eV with a dose of 8 J/cm2. The spatial profile of the irradiated photodiodes was studied with 3.49 eV, 10.2 eV and 100 eV quanta. The effect of the recovery of the response spatial profile has been proved for the p+-n diode. An additional useful method of visualization of irradiated photodiode area is also presented.

  9. Cost Effective Simulation of the Hybrid Solar/wind and Diesel Energy System in Rural Area

    NASA Astrophysics Data System (ADS)

    Sim, Ee. Y.; Barsoum, Nader

    2008-10-01

    This paper describes the optimization of a hybrid energy system model. Currently in Sarawak, people living in the rural areas still depend on diesel generators to generate electricity. This increases the demand for fossil fuel, creates noise pollution and toxic gas is emitted to the environment. Hence, hybrid energy systems were introduced to replace this conventional energy system as well as improving the living standard in the villages. In this paper, several hybrid energy system configurations were investigated in order to find out the most cost effective hybrid system through Hybrid Optimization Model for Electric Renewability (Homer) software. Homer simulates, optimizes, and analyzes the sensitivity variables for each of the system configurations.

  10. Synchronous Photodiode-Signal Sampler

    NASA Technical Reports Server (NTRS)

    Primus, Howard K.

    1988-01-01

    Synchronous sampling circuit increases signal-to-noise ratio of measurements of chopped signal of known phase and frequency in presence of low-frequency or dc background noise. Used with linear array of photoelectric sensors for locating edge of metal plate. Multiplexing circuit cycles through 16 light-emitting-diode/photodiode pairs, under computer control. Synchronized with multiplexer so edge detector makes one background-subtracted signal measurement per emitter/detector pair in turn.

  11. Novel vertical silicon photodiodes based on salicided polysilicon trenched contacts

    SciTech Connect

    Kaminski, Yelena; Shauly, Eitan; Paz, Yaron

    2015-12-07

    The classical concept of silicon photodiodes comprises of a planar design characterized by heavily doped emitters. Such geometry has low collection efficiency of the photons absorbed close to the surface. An alternative, promising, approach is to use a vertical design. Nevertheless, realization of such design is technologically challenged, hence hardly explored. Herein, a novel type of silicon photodiodes, based on salicided polysilicon trenched contacts, is presented. These contacts can be prepared up to 10 μm in depth, without showing any leakage current associated with the increase in the contact area. Consequently, the trenched photodiodes revealed better performance than no-trench photodiodes. A simple two dimensional model was developed, allowing to estimate the conditions under which a vertical design has the potential to have better performance than that of a planar design. At large, the deeper the trench is, the better is the vertical design relative to the planar (up to 10 μm for silicon). The vertical design is more advantageous for materials characterized by short diffusion lengths of the carriers. Salicided polysilicon trenched contacts open new opportunities for the design of solar cells and image sensors. For example, these contacts may passivate high contact area buried contacts, by virtue of the conformity of polysilicon interlayer, thus lowering the via resistance induced recombination enhancement effect.

  12. Ultraviolet avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    McClintock, Ryan; Razeghi, Manijeh

    2015-08-01

    The III-Nitride material system is rapidly maturing; having proved itself as a material for LEDs and laser, and now finding use in the area of UV photodetectors. However, many UV applications are still dominated by the use of photomultiplier tubes (PMT). PMTs are capable of obtaining very high sensitivity using internal electron multiplication gain (typically ~106). It is highly desirable to develop a compact semiconductor-based photodetector capable of realizing this level of sensitivity. In principle, this can be obtained in III-Nitrides by taking advantage of avalanche multiplication under high electric fields - typically 2.7 MV/cm, which with proper design can correspond to an external reverse bias of less than 100 volts. In this talk, we review the current state-of-the-art in III-Nitride solar- and visible-blind APDs, and present our latest results on GaN APDs grown on both conventional sapphire and low dislocation density free-standing c- and m-plane GaN substrates. Leakage current, gain, and single photon detection efficiency (SPDE) of these APDs were compared. The spectral response and Geiger-mode photon counting performance of UV APDs are studied under low photon fluxes, with single photon detection capabilities as much as 30% being demonstrated in smaller devices. Geiger-mode operation conditions are optimized for enhanced SPDE.

  13. A motion gesture sensor using photodiodes with limited field-of-view.

    PubMed

    Kim, Yong Sin; Baek, Kwang-Hyun

    2013-04-22

    This paper presents a low-power and small-size motion gesture sensor (MGS) based on an active infrared (IR) proximity sensor. While conventional proximity-based MGSs require two LEDs (the most power-hungry components) and one photodiode, the proposed MGS eliminates one of LEDs at the expense of an additional photodiode as a separate channel. In conjunction with an optical block that limits the field-of-view of each photodiode, the power consumption and area of the proposed MGS can be reduced by up to 52% and 69%, respectively, compared with conventional proximity-based MGSs. Optical simulation and test results validate theoretical analysis presented. PMID:23609631

  14. Hybrid and Online Climate Instruction at Madison Area Technical College

    NASA Astrophysics Data System (ADS)

    Lindstrom, S. S.; Lazzara, M. A.; Harkey, M. K.; Lynds, S. E.

    2012-12-01

    A NASA-funded initiative to develop climate instruction to underserved populations, such as those enrolled in Community Colleges, has funded the development of a hybrid and an online class on Climate and Climate Change. We will present here the class structure, topics, results from the first course offering and plans for future improvement, as well as a discussion of differences resulting from course delivery format. Because this class was offered in Wisconsin, some of the readings focused on possible agricultural changes due to changing climate as well as how the climate normals changed this year. The class also sponsored two internships for students at Madison's local Electric/Gas supplier, and how that furthered their education will be discussed as well.

  15. Polarization switch of four-wave mixing in large mode area hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

    2015-02-15

    Degenerate spontaneous four-wave mixing is considered in a large mode area hybrid photonic crystal fiber. Numerical and experimental results show birefringence assisted four-wave mixing for a certain polarization state of the pump field. The parametric gain can be turned on and off by switching the polarization state of the pump field between the two principal axis of the hybrid photonic crystal fiber. PMID:25680131

  16. Scholarly Communication and Network Influences in the Hybrid Problem Area of Developmental Dyslexia.

    ERIC Educational Resources Information Center

    Perry, Claudia A.; Rice, Ronald E.

    1996-01-01

    A scientific communication model of the emergence of a hybrid research area was tested on 74 researchers in the field of developmental dyslexia. Results show support for a model of Mulkay's model branching instead of Kuhn's model of scientific revolution; evidence points to divergence rather than convergence among the related research areas.…

  17. Note: Effect of photodiode aluminum cathode frame on spectral sensitivity in the soft x-ray energy band

    SciTech Connect

    McGarry, M. B. Den Hartog, D. J.; Goetz, J. A.; Johnson, J.; Franz, P.

    2014-09-15

    Silicon photodiodes used for soft x-ray detection typically have a thin metal electrode partially covering the active area of the photodiode, which subtly alters the spectral sensitivity of the photodiode. As a specific example, AXUV4BST photodiodes from International Radiation Detectors have a 1.0 μm thick aluminum frame covering 19% of the active area of the photodiode, which attenuates the measured x-ray signal below ∼6 keV. This effect has a small systematic impact on the electron temperature calculated from measurements of soft x-ray bremsstrahlung emission from a high-temperature plasma. Although the systematic error introduced by the aluminum frame is only a few percent in typical experimental conditions on the Madison Symmetric Torus, it may be more significant for other instruments that use similar detectors.

  18. Note: Effect of photodiode aluminum cathode frame on spectral sensitivity in the soft x-ray energy band

    NASA Astrophysics Data System (ADS)

    McGarry, M. B.; Franz, P.; Den Hartog, D. J.; Goetz, J. A.; Johnson, J.

    2014-09-01

    Silicon photodiodes used for soft x-ray detection typically have a thin metal electrode partially covering the active area of the photodiode, which subtly alters the spectral sensitivity of the photodiode. As a specific example, AXUV4BST photodiodes from International Radiation Detectors have a 1.0 μm thick aluminum frame covering 19% of the active area of the photodiode, which attenuates the measured x-ray signal below ˜6 keV. This effect has a small systematic impact on the electron temperature calculated from measurements of soft x-ray bremsstrahlung emission from a high-temperature plasma. Although the systematic error introduced by the aluminum frame is only a few percent in typical experimental conditions on the Madison Symmetric Torus, it may be more significant for other instruments that use similar detectors.

  19. Electronic hybridization of large-area stacked graphene films.

    PubMed

    Robinson, Jeremy T; Schmucker, Scott W; Diaconescu, C Bogdan; Long, James P; Culbertson, James C; Ohta, Taisuke; Friedman, Adam L; Beechem, Thomas E

    2013-01-22

    Direct, tunable coupling between individually assembled graphene layers is a next step toward designer two-dimensional (2D) crystal systems, with relevance for fundamental studies and technological applications. Here we describe the fabrication and characterization of large-area (>cm(2)), coupled bilayer graphene on SiO(2)/Si substrates. Stacking two graphene films leads to direct electronic interactions between layers, where the resulting film properties are determined by the local twist angle. Polycrystalline bilayer films have a "stained-glass window" appearance explained by the emergence of a narrow absorption band in the visible spectrum that depends on twist angle. Direct measurement of layer orientation via electron diffraction, together with Raman and optical spectroscopy, confirms the persistence of clean interfaces over large areas. Finally, we demonstrate that interlayer coupling can be reversibly turned off through chemical modification, enabling optical-based chemical detection schemes. Together, these results suggest that 2D crystals can be individually assembled to form electronically coupled systems suitable for large-scale applications. PMID:23240977

  20. Scholarly Communication in Developmental Dyslexia: Influence of Network Structure on Change in a Hybrid Problem Area.

    ERIC Educational Resources Information Center

    Perry, Claudia A.; Rice, Ronald E.

    1998-01-01

    Based on Mulkay's and Kuhn's models of change in scientific structure, a scientific communication model of the emergence of a hybrid research area was developed and tested in the field of developmental dyslexia; 74 researchers were partitioned into "blocks" of similar scientists. Results show support for Mulkay's model of branching instead of…

  1. Integrating an electrically active colloidal quantum dot photodiode with a graphene phototransistor

    PubMed Central

    Nikitskiy, Ivan; Goossens, Stijn; Kufer, Dominik; Lasanta, Tania; Navickaite, Gabriele; Koppens, Frank H. L.; Konstantatos, Gerasimos

    2016-01-01

    The realization of low-cost photodetectors with high sensitivity, high quantum efficiency, high gain and fast photoresponse in the visible and short-wave infrared remains one of the challenges in optoelectronics. Two classes of photodetectors that have been developed are photodiodes and phototransistors, each of them with specific drawbacks. Here we merge both types into a hybrid photodetector device by integrating a colloidal quantum dot photodiode atop a graphene phototransistor. Our hybrid detector overcomes the limitations of a phototransistor in terms of speed, quantum efficiency and linear dynamic range. We report quantum efficiencies in excess of 70%, gain of 105 and linear dynamic range of 110 dB and 3 dB bandwidth of 1.5 kHz. This constitutes a demonstration of an optoelectronically active device integrated directly atop graphene and paves the way towards a generation of flexible highly performing hybrid two-dimensional (2D)/0D optoelectronics. PMID:27311710

  2. Integrating an electrically active colloidal quantum dot photodiode with a graphene phototransistor.

    PubMed

    Nikitskiy, Ivan; Goossens, Stijn; Kufer, Dominik; Lasanta, Tania; Navickaite, Gabriele; Koppens, Frank H L; Konstantatos, Gerasimos

    2016-01-01

    The realization of low-cost photodetectors with high sensitivity, high quantum efficiency, high gain and fast photoresponse in the visible and short-wave infrared remains one of the challenges in optoelectronics. Two classes of photodetectors that have been developed are photodiodes and phototransistors, each of them with specific drawbacks. Here we merge both types into a hybrid photodetector device by integrating a colloidal quantum dot photodiode atop a graphene phototransistor. Our hybrid detector overcomes the limitations of a phototransistor in terms of speed, quantum efficiency and linear dynamic range. We report quantum efficiencies in excess of 70%, gain of 10(5) and linear dynamic range of 110 dB and 3 dB bandwidth of 1.5 kHz. This constitutes a demonstration of an optoelectronically active device integrated directly atop graphene and paves the way towards a generation of flexible highly performing hybrid two-dimensional (2D)/0D optoelectronics. PMID:27311710

  3. Photodiode-Based, Passive Ultraviolet Dosimeters

    NASA Technical Reports Server (NTRS)

    Vaughn, Jason A.; Gray, Perry

    2004-01-01

    Simple, passive instruments have been developed for measuring the exposure of material specimens to vacuum ultraviolet (VUV) radiation from the Sun. Each instrument contains a silicon photodiode and a coulometer. The photocharge generated in the photodiode is stored in the coulometer. The accumulated electric charge measured by use of the coulometer is assumed to be proportional to the cumulative dose of VUV radiation expressed in such convenient units as equivalent Sun hours (ESH) [defined as the number of hours of exposure to sunlight at normal incidence]. Intended originally for use aboard spacecraft, these instruments could also be adapted to such terrestrial uses as monitoring the curing of ultraviolet-curable epoxies. Each instrument includes a photodiode and a coulometer assembly mounted on an interface plate (see figure). The photodiode assembly includes an aluminum housing that holds the photodiode, a poly(tetrafluoroehylene) cosine receptor, and a narrow-band optical filter. The cosine receptor ensures that the angular response of the instrument approximates the ideal angular response (proportional to the cosine of the angle of incidence). The filter is chosen to pass the ultraviolet wavelength of interest in a specific experiment. The photodiode is electrically connected to the coulometer. The factor of proportionality between the charge stored in the coulometer and ultraviolet dosage (in units of ESH) is established, prior to use, in calibration experiments that involve the use of lamps and current sources traceable to the National Institute of Standards and Technology.

  4. Sustainable electricity generation by solar pv/diesel hybrid system without storage for off grids areas

    NASA Astrophysics Data System (ADS)

    Azoumah, Y.; Yamegueu, D.; Py, X.

    2012-02-01

    Access to energy is known as a key issue for poverty reduction. The electrification rate of sub Saharan countries is one of the lowest among the developing countries. However this part of the world has natural energy resources that could help raising its access to energy, then its economic development. An original "flexy energy" concept of hybrid solar pv/diesel/biofuel power plant, without battery storage, is developed in order to not only make access to energy possible for rural and peri-urban populations in Africa (by reducing the electricity generation cost) but also to make the electricity production sustainable in these areas. Some experimental results conducted on this concept prototype show that the sizing of a pv/diesel hybrid system by taking into account the solar radiation and the load/demand profile of a typical area may lead the diesel generator to operate near its optimal point (70-90 % of its nominal power). Results also show that for a reliability of a PV/diesel hybrid system, the rated power of the diesel generator should be equal to the peak load. By the way, it has been verified through this study that the functioning of a pv/Diesel hybrid system is efficient for higher load and higher solar radiation.

  5. Optical receivers with large-diameter photodiode

    NASA Astrophysics Data System (ADS)

    Swoboda, Robert; Schneider, Kerstin; Zimmermann, Horst

    2006-04-01

    This work presents two types of optical receivers with large-diameter photodiodes. Both are optoelectronic integrated circuits (OEICs) realized in 0.6μm BiCMOS Si technology integrating PIN photodiode, transimpedance amplifier (TIA) and output circuit on chip. The two circuits are an optocoupler with a photodiode diameter of 780μm and a rise- and falltime of 5ns and 4.9ns respectively at 850nm light and a plastic optical fiber (POF) receiver with a photodiode diameter of 500μm and upper -3dB cut-off frequencies of 165MHz at 660nm light and 148MHz at 850nm light. The measured rise- and falltime of the POF receiver was 1.78ns and 2.45ns at 660nm light and 1.94ns and 2.5ns at 850ns, respectively. The presented results combine the advantage of easier handling of large-diameter photodiode receivers and high performance.

  6. Vertical Isolation for Photodiodes in CMOS Imagers

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata

    2008-01-01

    In a proposed improvement in complementary metal oxide/semi conduct - or (CMOS) image detectors, two additional implants in each pixel would effect vertical isolation between the metal oxide/semiconductor field-effect transistors (MOSFETs) and the photodiode of the pixel. This improvement is expected to enable separate optimization of the designs of the photodiode and the MOSFETs so as to optimize their performances independently of each other. The purpose to be served by enabling this separate optimization is to eliminate or vastly reduce diffusion cross-talk, thereby increasing sensitivity, effective spatial resolution, and color fidelity while reducing noise.

  7. Photon counting modules using RCA silicon avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Lightstone, Alexander W.; Macgregor, Andrew D.; Macsween, Darlene E.; Mcintyre, Robert J.; Trottier, Claude; Webb, Paul P.

    1989-01-01

    Avalanche photodiodes (APD) are excellent small area, solid state detectors for photon counting. Performance possibilities include: photon detection efficiency in excess of 50 percent; wavelength response from 400 to 1000 nm; count rate to 10 (exp 7) counts per sec; afterpulsing at negligible levels; timing resolution better than 1 ns. Unfortunately, these performance levels are not simultaneously available in a single detector amplifier configuration. By considering theoretical performance predictions and previous and new measurements of APD performance, the anticipated performance of a range of proposed APD-based photon counting modules is derived.

  8. Study of Oil spill in Norwegian area using Decomposition Techniques on RISAT-1 Hybrid Polarimetric Data.

    NASA Astrophysics Data System (ADS)

    Jayasri, P. V.; Usha Sundari, H. S. V.; Kumari, E. V. S. Sita; Prasad, A. V. V.

    2014-11-01

    Over past few years Synthetic Aperture Radar(SAR) has received a considerable attention for monitoring and detection of oil spill due to its unique capabilities to provide wide-area surveillance and day and night measurements, almost independently from atmospheric conditions. The critical part of the oil spill detection is to distinguish oil spills from other natural phenomena. Stokes vector analysis of the image data is studied to estimate the polarized circular and linear components of the backscatter signal which essentially utilize the degree of polarization(m) and relative phase (δ) of the target. In a controlled oil spill experiment conducted at Norwegian bay during 17th to 22nd June 2014, RISAT-1 hybrid polarimetry images were utilized to study the characteristics of oil spill in the sea. The preliminary results obtained by using polarimetric decomposition technique on hybrid polarimetric data to decipher the polarimetric characteristics of oil spills from natural waters are discussed in the paper.

  9. Current isolating epitaxial buffer layers for high voltage photodiode array

    DOEpatents

    Morse, Jeffrey D.; Cooper, Gregory A.

    2002-01-01

    An array of photodiodes in series on a common semi-insulating substrate has a non-conductive buffer layer between the photodiodes and the semi-insulating substrate. The buffer layer reduces current injection leakage between the photodiodes of the array and allows optical energy to be converted to high voltage electrical energy.

  10. Optical Demonstrations with a Scanning Photodiode Array.

    ERIC Educational Resources Information Center

    Turman, Bobby N.

    1980-01-01

    Describes the photodiode array and the electrical connections necessary for it. Also shows a few of the optical demonstration possibilities-shadowgraphs for measuring small objects, interference and diffraction effects, angular resolution of an optical system, and a simple spectrometer. (Author/DS)

  11. MRS photodiode in strong magnetic field

    SciTech Connect

    Beznosko, D.; Blazey, G.; Dyshkant, A.; Francis, K.; Kubik, D.; Rykalin, V.; Tartaglia, M.A.; Zutshi, v.; /Northern Illinois U.

    2004-12-01

    The experimental results on the performance of the MRS (Metal/Resistor/Semiconductor) photodiode in the strong magnetic field of 4.4T, and the possible impact of the quench of the magnet at 4.5T on sensor's operation are reported.

  12. Study of hybrid power system potential to power agricultural water pump in mountain area

    NASA Astrophysics Data System (ADS)

    Syuhada, Ahmad; Mubarak, Amir Zaki; Maulana, M. Ilham

    2016-03-01

    As industry and Indonesian economy grow fast, there are a lot of agricultural land has changed into housing and industrial land. This causes the agricultural land moves to mountain area. In mountainous agricultural area, farmers use the water resources of small rivers in the groove of the mountain to irrigate the farmland. Farmers use their power to lift up water from the river to their land which causes inefectivity in the work of the farmers. Farmers who have capital utilize pump to raise water to their land. The only way to use pump in mountain area is by using fuel energy as there is no electricity, and the fuel price in mountain area is very expensive. Based on those reasons it is wise to consider the exploration of renewable energy available in the area such as solar energy, wind energy and hybrid energy. This study analyses the potential of the application of hybrid power plant, which is the combination of solar and wind energy, to power agricultural pump. In this research, the data of wind speed and solar radiation are collected from the measurement of BMKG SMPK Plus Sare. Related to the solar energy, the photovoltaic output power calculation is 193 W with duration of irradiation of 5 hours/day. While for the wind energy, the output power of the wind turbine is 459.84 W with blade diameter of 3 m and blow duration of 7 hours/day. The power of the pump is 558 W with 8 hours of usage, and the water capacity is 2.520 liters/hour for farmland with the area of 15 ha. Based on the analysis result, the designed system will generate electricity of 3.210 kW/year with initial investment of US 14,938.

  13. 4H-SiC Schottky photodiodes for ultraviolet flame detection

    NASA Astrophysics Data System (ADS)

    Mazzillo, M.; Sciuto, A.

    2015-10-01

    In the last few years silicon carbide (SiC) has emerged as an appropriate material for the detection of very low ultraviolet photon fluxes even at elevated temperatures. In this paper we report on the electro-optical characteristics of large area interdigit Ni2Si/4H-SiC photodiodes in TO metal can package with a suitable molded cap quartz window with high transmission in the ultraviolet wavelength range. The detectors have been tested for the detection of the ultraviolet component of the yellow flame emitted by a small candle, showing good sensitivity for very weak photon fluxes notwithstanding the linear operation condition of the photodiodes.

  14. Experimental characterization of peripheral photocurrent in CMOS photodiodes down to 65 nm technology

    NASA Astrophysics Data System (ADS)

    Blanco-Filgueira, B.; López, P.; Roldán, J. B.

    2013-04-01

    In this work, an in-depth experimental characterization of submicron CMOS p-n+ junction photodiodes operating under uniform illumination in the visible range is performed. The experimental measurements are used to validate a previous two-dimensional analytical model for the photoresponse estimation of these structures, which pays special attention to the lateral collection and was verified by means of device simulations. To do so, square p-n+ junction photodiodes with different sizes down to an active area of 0.56 μm wide have been fabricated in 180 and 65 nm technological nodes and characterized under blue, green and red light sources. As a result, the importance of the lateral collection in the overall response for small photodiodes that was previously theoretically reported is confirmed. The experimentally validated two-dimensional analytical model is a powerful tool that can be employed for the design of CMOS imagers and related electronics circuits.

  15. Producibility of Vertically Integrated Photodiode (VIP)tm scanning focal plane arrays

    NASA Astrophysics Data System (ADS)

    Turner, Arthur M.; Teherani, Towfik; Ehmke, John C.; Pettitt, Cindy; Conlon, Peggy; Beck, Jeffrey D.; McCormack, Kent; Colombo, Luigi; Lahutsky, Tom; Murphy, Terry; Williams, Robert L.

    1994-07-01

    Vertically integrated photodiode, VIPTM, technology is now being used to produce second generation infrared focal plane arrays with high yields and performance. The VIPTM process employs planar, ion implanted, n on p diodes in HgCdTe which is epoxy hybridized directly to the read out integrated circuits on 100 mm Si wafers. The process parameters that are critical for high performance and yield include: HgCdTe dislocation density and thickness, backside passivation, frontside passivation, and junction formation. Producibility of infrared focal plane arrays (IRFPAs) is also significantly enhanced by read out integrated circuits (ROICs) which have the ability to deselect defective pixels. Cold probe screening before lab dewar assembly reduces costs and improves cycle times. The 240 X 1 and 240 X 2 scanning array formats are used to demonstrate the effect of process optimization, deselect, and cold probe screening on yield and cycle time. The versatility of the VIPTM technology and its extension to large area arrays is demonstrated using 240/288 X 4 and 480 X 5 TDI formats. Finally, the high performance of VIPTM IRFPAs is demonstrated by comparing data from a 480 X 5 to the SADA-II specification.

  16. Large-Format AlGaN PIN Photodiode Arrays for UV Images

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid; Franz, David

    2010-01-01

    A large-format hybridized AlGaN photodiode array with an adjustable bandwidth features stray-light control, ultralow dark-current noise to reduce cooling requirements, and much higher radiation tolerance than previous technologies. This technology reduces the size, mass, power, and cost of future ultraviolet (UV) detection instruments by using lightweight, low-voltage AlGaN detectors in a hybrid detector/multiplexer configuration. The solar-blind feature eliminates the need for additional visible light rejection and reduces the sensitivity of the system to stray light that can contaminate observations.

  17. Degenerate four wave mixing in large mode area hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Lægsgaard, Jesper

    2013-07-29

    Spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers, in which photonic bandgap guidance and index guidance is combined. Calculations show the parametric gain is maximum on the edge of a photonic bandgap, for a large range of pump wavelengths. The FWM products are observed on the edges of a transmission band experimentally, in good agreement with the numerical results. Thereby the bandedges can be used to control the spectral positions of FWM products through a proper fiber design. The parametric gain control combined with a large mode area fiber design potentially allows for power scaling of light at wavelengths not easily accessible with e.g. rare earth ions. PMID:23938682

  18. Type-II Superlattice Avalanche Photodiodes

    NASA Astrophysics Data System (ADS)

    Huang, Jun

    Type-II superlattice avalanche photodiodes have shown advantages compared to conventional mercury cadmium telluride photodiodes for infrared wavelength detection. However, surface or interface leakage current has been a major issue for superlattice avalanche photodiodes, especially in infrared wavelength region. First, passivation of the superlattice device with ammonium sulfide and thioacetamide was carried out, and its surface quality was studied by X-ray Photoelectron Spectroscopy. The study showed that both ammonium sulfide and thiacetamide passivation can actively remove the native oxide at the surface. Thiacetamide passivation combine more sulfur bonds with III-V elements than that of ammonium sulfide. Another X-ray photoelectron spectra of thiacetamide-treated atomic layer deposited zinc sulfide capped InAs/GaSb superlattice was performed to investigate the interface sulfur bond conditions. Sb--S and As--S bonds disappear while In-S bond gets enhanced, indicating that Indium Sulfide should be the major components at the interface after ZnS deposition. Second, the simulation of electrical characteristics for zinc sulfide, silicon nitride and silicon dioxide passivated superlattice devices was performed by SILVACO software to fit the experimental results and to discover the surface current mechanism. Different surface current mechanism strengths were found. Third, several novel dual-carrier avalanche photodiode structures were designed and simulated. The structures had alternate carrier multiplication regions, placed next to a wider electron multiplication region, creating dual-carrier multiplication feedback systems. Gain and excess noise factor of these structures were simulated and compared based on the dead space multiplication theory under uniform electric field. From the simulation, the applied bias can be greatly lowered or the thickness can be shrunk to achieve the same gain from the conventional device. The width of the thin region was the most

  19. High Performance Photodiode Based on p-Si/Copper Phthalocyanine Heterojunction.

    PubMed

    Zhong, Junkang; Peng, Yingquan; Zheng, Tingcai; Lv, Wenli; Ren, Qiang; Fobao, Huang; Ying, Wang; Chen, Zhen; Tang, Ying

    2016-06-01

    Hybrid organic-inorganic (HOI) photodiodes have both advantages of organic and inorganic materials, including compatibility of traditional Si-based semiconductor technology, low cost, high photosensitivity and high reliability, showing tremendous value in application. Red light sensitive HOI photodiodes based on the p-Si/copper phthalocyanine (CuPc) hetrojunction were fabricated and characterized. The effects of CuPc layer thickness on the performance were investigated, and an optimal layer thickness of around 30 nm was determined. An analytical expression is derived to describe the measured thickness dependence of the saturation photocurrent. For the device with optimal CuPc layer thickness, a photoresponsivity of 0.35 A/W and external quantum efficiency of 70% were obtained at 9 V reverse voltage bias and 655 nm light illumination of 0.451 mW. Furthermore, optical power dependent performances were investigated. PMID:27427631

  20. Large-area, freestanding, single-layer graphene-gold: a hybrid plasmonic nanostructure.

    PubMed

    Iyer, Ganjigunte R Swathi; Wang, Jian; Wells, Garth; Guruvenket, Srinivasan; Payne, Scott; Bradley, Michael; Borondics, Ferenc

    2014-06-24

    Graphene-based plasmonic devices have recently drawn great attention. However, practical limitations in fabrication and device architectures prevent studies from being carried out on the intrinsic properties of graphene and their change by plasmonic structures. The influence of a quasi-infinite object (i.e., the substrate) on graphene, being a single sheet of carbon atoms, and the plasmonic device is overwhelming. To address this and put the intrinsic properties of the graphene-plasmonic nanostructures in focus, we fabricate large-area, freestanding, single-layer graphene-gold (LFG-Au) sandwich structures and Au nanoparticle decorated graphene (formed via thermal treatment) hybrid plasmonic nanostructures. We observed two distinct plasmonic enhancement routes of graphene unique to each structure via surface-enhanced Raman spectroscopy. The localized electronic structure variation in the LFG due to graphene-Au interaction at the nanoscale is mapped using scanning transmission X-ray microscopy. The measurements show an optical density of ∼0.007, which is the smallest experimentally determined for single-layer graphene thus far. Our results on freestanding graphene-Au plasmonic structures provide great insight for the rational design and future fabrication of graphene plasmonic hybrid nanostructures. PMID:24860924

  1. Fabrication of large-area arrays of hybrid nanostructures on polymer-derived chemically patterned surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoying; Nepal, Dhriti; Biswas, Sushmita; Park, Kyoungweon; Vaia, Richard; Nealey, Paul; Air Force Research Laboratories Collaboration; University of Chicago Team

    2014-03-01

    The precise placement and assembly of nanoparticles (NPs) into large-area nanostructure arrays will allow for the design and implementation of advanced nanoscale devices for applications in fields such as quantum computing, optical sensing, superlenses, photocatalysis, photovoltaics, and non-linear optics. Our work is focused on using chemically nanopatterned surfaces to fabricate arrays of hybrid nanostructures with each component of the building block at well-defined positions. The precise chemical contrast patterns with densities and resolution of features created using standard tools of lithography, polymer self-assembly, and surface functionalization allow for control of position and interparticle spacing through selective surface-particle and particle-particle interactions. We have demonstrated the assembly of NPs, including metallic NPs and semiconductor quantum dots, into arrays of hybrid structures with various geometries, such as monomers, dimers, quatrefoils, stripes, and chains. We have developed protocols to fabricate NP arrays over a variety of substrates, which allows for the design and characterization of optical and electronic nanostructures and devices to meet the requirements of various technological applications.

  2. The large-area hybrid-optics CLAS12 RICH detector: Tests of innovative components

    SciTech Connect

    Contalbrigo, M; Baltzell, N; Benmokhtar, F; Barion, L; Cisbani, E; El Alaoui, A; Hafidi, K; Hoek, M; Kubarovsky, V; Lagamba, L; Lucherini, V; Malaguti, R; Mirazita, M; Montgomery, R; Movsisyan, A; Musico, P; Orecchini, D; Orlandi, A; Pappalardo, L L; Pereira, S; Perrino, R; Phillips, J; Pisano, S; Rossi, P; Squerzanti, S; Tomassini, S; Turisini, M; Viticchiè, A

    2014-07-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here.

  3. Hybrid multiphase CFD simulation for liquid-liquid interfacial area prediction in annular centrifugal contactors

    SciTech Connect

    Wardle, K.E.

    2013-07-01

    Liquid-liquid contacting equipment used in solvent extraction processes has the dual purpose of mixing and separating two immiscible fluids. Consequently, such devices inherently encompass a wide variety of multiphase flow regimes. A hybrid multiphase computational fluid dynamics (CFD) solver which combines the Eulerian multi-fluid method with VOF (volume of fluid) sharp interface capturing has been developed for application to annular centrifugal contactors. This solver has been extended to enable prediction of mean droplet size and liquid-liquid interfacial area through a single moment population balance method. Simulations of liquid-liquid mixing in a simplified geometry and a model annular centrifugal contactor are reported with droplet breakup/coalescence models being calibrated versus available experimental data. Quantitative comparison is made for two different housing vane geometries and it is found that the predicted droplet size is significantly smaller for vane geometries which result in higher annular liquid holdup.

  4. The large-area hybrid-optics CLAS12 RICH detector: Tests of innovative components

    NASA Astrophysics Data System (ADS)

    Contalbrigo, M.; Baltzell, N.; Benmokhtar, F.; Barion, L.; Cisbani, E.; El Alaoui, A.; Hafidi, K.; Hoek, M.; Kubarovsky, V.; Lagamba, L.; Lucherini, V.; Malaguti, R.; Mirazita, M.; Montgomery, R.; Movsisyan, A.; Musico, P.; Orecchini, D.; Orlandi, A.; Pappalardo, L. L.; Pereira, S.; Perrino, R.; Phillips, J.; Pisano, S.; Rossi, P.; Squerzanti, S.; Tomassini, S.; Turisini, M.; Viticchiè, A.

    2014-12-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here.

  5. Silicon photodiode as the two-color detector

    NASA Astrophysics Data System (ADS)

    Ponomarev, D. B.; Zakharenko, V. A.

    2015-11-01

    This paper describes a silicon photodiode as the two-color photodetector. The work of one photodiode in two spectral ranges is achieved due to the changes of the spectral sensitivity of the photodiodes in the transition from photodiode mode for photovoltaic in the short circuit mode. On the basis of silicon photodiode FD-256 the layout of the spectral ratio pyrometer was assembled and the results of theoretical calculations was confirmed experimentally. The calculated dependences of the coefficient of error of the spectral ratio pyrometer from temperature reverse voltage 10 and 100 V was presented. The calculated dependence of the instrumental error and the assessment of methodological errors of the proposed photodetector spectral ratio was done. According to the results of the presented research was set the task of development photodiode detectors which change the spectral sensitivity depending on the applied voltage.

  6. Status of the development of large area photon detectors based on THGEMs and hybrid MPGD architectures for Cherenkov imaging applications

    NASA Astrophysics Data System (ADS)

    Alexeev, M.; Birsa, R.; Bradamante, F.; Bressan, A.; Büchele, M.; Chiosso, M.; Ciliberti, P.; Torre, S. Dalla; Dasgupta, S.; Denisov, O.; Duic, V.; Finger, M.; Finger, M.; Fischer, H.; Giorgi, M.; Gobbo, B.; Gregori, M.; Herrmann, F.; Königsmann, K.; Levorato, S.; Maggiora, A.; Martin, A.; Menon, G.; Steiger, K.; Novy, J.; Panzieri, D.; Pereira, F. A.; Santos, C. A.; Sbrizzai, G.; Schiavon, P.; Schopferer, S.; Slunecka, M.; Sozzi, F.; Steiger, L.; Sulc, M.; Takekawa, S.; Tessarotto, F.; Veloso, J. F. C. A.; Makke, N.

    2016-07-01

    We report about the development status of large area gaseous single photon detectors based on a novel hybrid concept for RICH applications. The hybrid concept combines Thick Gaseous Electron Multipliers (THGEMs) coupled to CsI, working as a photon sensitive pre-amplification stage, and Micromegas, as a multiplication stage. The most recent achievements within the research and development programme consist in the assembly and study of 300 × 300mm2 hybrid photon detectors, the optimization of front-end electronics, and engineering towards large area detectors. Hybrid detectors with an active area of 300 × 300mm2 have been successfully operated in laboratory conditions and at a CERN PS T10 test beam, achieving effective gains in the order of 105 and good time resolution (σ = 7 ns); APV25 front-end chips have been coupled to the detector resulting in noise levels lower than 1000 electrons; the production and characterization of 300 × 600mm2 THGEMs is ongoing. A set of hybrid detectors with 600 × 600mm2 active area is envisaged to upgrade COMPASS RICH-1 at CERN in 2016.

  7. Nano-multiplication region avalanche photodiodes and arrays

    NASA Technical Reports Server (NTRS)

    Zheng, Xinyu (Inventor); Pain, Bedabrata (Inventor); Cunningham, Thomas J. (Inventor)

    2011-01-01

    An avalanche photodiode with a nano-scale reach-through structure comprising n-doped and p-doped regions, formed on a silicon island on an insulator, so that the avalanche photodiode may be electrically isolated from other circuitry on other silicon islands on the same silicon chip as the avalanche photodiode. For some embodiments, multiplied holes generated by an avalanche reduces the electric field in the depletion region of the n-doped and p-doped regions to bring about self-quenching of the avalanche photodiode. Other embodiments are described and claimed.

  8. High resolution, low energy avalanche photodiode X-ray detectors

    NASA Technical Reports Server (NTRS)

    Farrell, R.; Vanderpuye, K.; Entine, G.; Squillante, M. R.

    1991-01-01

    Silicon avalanche photodiodes have been fabricated, and their performance as X-ray detectors has been measured. Photon sensitivity and energy resolution were measured as a function of size and operating parameters. Noise thresholds as low as 212 eV were obtained at room temperature, and backscatter X-ray fluorescence data were obtained for aluminum and other light elements. It is concluded that the results with the X-ray detector are extremely encouraging, and the performance is challenging the best available proportional counters. While not at the performance level of either cryogenic silicon or HgI2, these device operate at room temperature and can be reproduced in large numbers and with much larger areas than typically achieved with HgI2. In addition, they are rugged and appear to be indefinitely stable.

  9. Some tests of avalanche photodiodes produced by Advanced Photonix, Inc.

    SciTech Connect

    Foster, G.W.; Ronzhin, A.; Rusack, R.

    1995-08-01

    The goal of the measurements presented here is to check some parameters of the high gain avalanche photodiodes (APD`s) produced by Advanced Photonix, Inc. Samples with 16 mm and 5 mm diameter sensitive areas were tested. The tests were performed at FNAL. The new photomultiplier testing facility were used for gain measurements, linearity, and nonuniformity studies. The setup consists of laser with shifted wavelength of 440 nm, 10 Hz repetition rate and a pulse duration of 15 nsec. The laser light was transported to the APD by 1 mm diameter clear fiber. An amount of laser light was adjusted by rotating wheels of fixed light attenuation. The dynamic range of the APD, an amplifier (AMP) and an ADC was about 1000. To get the nonuniformity data the APD was mounted on a moveable stage under management and control of computer. The positioning of the fiber along sensitive surface of the APD was better than 100 microns.

  10. Light induced tunnel effect in CNT-Si photodiode

    NASA Astrophysics Data System (ADS)

    Aramo, C.; Ambrosio, M.; Bonavolontà, C.; Boscardin, M.; Castrucci, P.; Crivellari, M.; De Crescenzi, M.; de Lisio, C.; Fiandrini, E.; Grossi, V.; Maddalena, P.; Passacantando, M.; Santucci, S.; Scarselli, M.; Valentini, A.; Valentino, M.

    2016-07-01

    Negative differential resistance (NDR), for which the current is a decreasing function of the voltage, has been observed in the current-voltage curves of several types of structures. We measured tunnelling current and NDR by illuminating large area heterojunction obtained by growing Multi Wall Carbon Nanotubes on the surface of n-doped Silicon substrate. In the absence of light, the current flow is null until a junction threshold of about 2.4 V is reached, beyond which the dark current flows at room temperature with a very low intensity of few nA. When illuminated, a current of tens nA is observed at a drain voltage of about 1.5 V. At higher voltage the current intensity decreases according to a negative resistance of the order of MΩ. In the following we report details of tunneling photodiode realized and negative resistance characteristics.

  11. Investigation of a photon counting avalanche photodiode from Hamamatsu photonics

    NASA Astrophysics Data System (ADS)

    Britvitch, I.; Musienko, Y.; Renker, D.

    2006-11-01

    Multi-cell avalanche photodiodes (APDs) operating in Geiger mode have been shown to be a very promising alternative to photomultiplier tubes for the detection of single photons at room temperature. Like a photomultiplier they have high gain and a fast rise time and they are insensitive to pickup. Beyond it they operate in high magnetic fields, are compact and need a relatively low bias voltage. It is expected that the MOS production technique makes them cheap. Recently PSI and Hamamatsu Photonics worked together for the development of a radiation-hard APD for CMS ECAL and had very good success. The development continued based on a similar design for a photon counting multielement Geiger-mode APD with an area of 1×1 mm 2. The properties of this device have been measured and will be reported.

  12. Photodiode properties of molecular beam epitaxial InSb on a heavily doped substrate

    NASA Astrophysics Data System (ADS)

    Sun, Weiguo; Fan, Huitao; Peng, Zhenyu; Zhang, Liang; Zhang, Xiaolei; Zhang, Lei; Lu, Zhengxiong; Si, Junjie; Emelyanov, E.; Putyato, M.; Semyagin, B.; Pchelyakov, O.; Preobrazhenskii, V.

    2014-01-01

    Photodiodes of InSb were fabricated on an epitaxial layer grown using molecular beam epitaxy (MBE). Thermal cleaning of the InSb (0 0 1) substrate surface, 2° towards the (1 1 1) B plane, was performed to remove the oxide. Photodiode properties of МВЕ-formed epitaxial InSb were demonstrated. Zero-bias resistance area product (R0A) measurements were taken at 80 K under room temperature background for a pixel size of 100 μm × 100 μm. Values were as high as 4.36 × 104 Ω/cm2, and the average value of R0A was 1.66 × 104 Ω/cm2. The peak response was 2.44 (A/W). The epitaxial InSb photodiodes were fabricated using the same process as bulk crystal InSb diodes with the exception of the junction formation method. These values are comparable to the properties of bulk crystal InSb photodiodes.

  13. High-quantum-efficiency 2.2-um InGaAs MOCVD photodiodes

    NASA Astrophysics Data System (ADS)

    Wojtczuk, Steven; Colter, Peter C.; Jhabvala, Murzy D.

    1997-04-01

    Photodiodes responding in the 0.8-2.3 micrometers wavelength range are of interest in a wide range of applications, from wind- shear detection systems which use eyesafe 2.1 micrometers lasers to differential absorption LIDAR aerosol measurements of CO2. In this paper, we report on uncooled, broadband, 2.25 micrometers lattice-mismatched 0.55eV In0.72Ga0.28As photodiode arrays, in which the cutoff wavelength has been 'extended' from the 1.65 micrometers which is standard for 0.74eV In0.53Ga0.47As lattice-matched to InP wafers. InxGa1-xAs step-grading layers were used to transition from the InP wafer to the final In0.72Ga0.28As photodiode material during the metal organic chemical vapor deposition epitaxial growth. Linear 64 X 1 photodiode arrays were made with an independently-verified external quantum efficiency above 50 percent from 0.8 to 2.2 micrometers using MgF2/ZnS dual layer antireflection coating. Average 300 degree K area-normalized dark current for these N/P diodes was 5 X 10-5 A/cm2 at 10mV reverse bias.

  14. Cooled avalanche photodiode used for photon detection

    NASA Technical Reports Server (NTRS)

    Robinson, Deborah L.; Metscher, Brian D.

    1987-01-01

    Commercial avalanche photodiodes have been operated as single-photon detectors at an optimum operating temperature and bias voltage. These detectors were found to be 1.5 to 3 times more sensitive than presently-available photomultiplier tubes (PPMTs). Both single-photon detection probability and detector noise increase with bias voltage; detection probabilities greater than 25 percent were obtained with detector noise levels comparable to the noise of a PMT; higher probabilities were measured at higher noise levels. The sources of noise and their dependence on temperature and bias voltage are discussed.

  15. Photon detection with cooled avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Metscher, B. D.

    1987-01-01

    Commercial avalanche photodiodes have been operated as single-photon detectors at an optimum operating temperature and bias voltage. These detectors were found to be 1.5-3 times more sensitive than presently available photomultiplier tubes (PMTs). Both single-photon detection probability and detector noise increase with bias voltage; detection probabilities greater than twice that of a PMT were obtained with detector noise levels below 100 counts per second. Higher probabilities were measured at higher noise levels. The sources of noise and their dependence on temperature and bias voltage are discussed.

  16. Avalanche Photodiode Arrays for Optical Communications Receivers

    NASA Technical Reports Server (NTRS)

    Srinivasan, M.; Vilnrotter, V.

    2001-01-01

    An avalanche photodiode (APD) array for ground-based optical communications receivers is investigated for the reception of optical signals through the turbulent atmosphere. Kolmogorov phase screen simulations are used to generate realistic spatial distributions of the received optical field. It is shown that use of an APD array for pulse-position modulation detection can improve performance by up to 4 dB over single APD detection in the presence of turbulence, but that photon-counting detector arrays yield even greater gains.

  17. Why small avalanche photodiodes are beautiful

    NASA Astrophysics Data System (ADS)

    Rees, Graham J.; David, John P. R.

    2003-07-01

    Conventional wisdom suggests that, for low avalanche noise, avalanche photodiodes should operate at low electric fields, where electron and hole ionisation coefficients can differ widely. However, the associated weak ionization requires long multiplication regions, which in turn demand high bias voltages and result in long carrier transit times, reducing device speed. Moreover, multiplication is particularly sensitive to temperature in this region. In this paper we discuss the effects of dead space on reducing noise in short devices and on the associated benefits in predicted response time and reduced temperature sensitivity. The paper is illustrated with work from the Sheffield group.

  18. Photodiodes for ten micrometer laser communication systems

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1972-01-01

    The performance is discussed of 10-micron mercury-cadmiumtelluride and lead-tin-telluride photodiodes in laser heterodyne communication systems. The dependence of detector quantum efficiency, resistance, frequency response, and signal-to-noise ratio on temperature, bias, and local oscillator power are examined. Included in the discussion is an analysis of the feasibility of high temperature operation, and ability of the detector to dissipate power to a heat sink is explored. Some aspects of direct detection response are considered and figures showing flux levels from a blackbody presented.

  19. Interference effects in Reticon photodiode array detectors

    NASA Astrophysics Data System (ADS)

    Mount, George H.; Sanders, Ryan W.; Brault, James W.

    1992-03-01

    A detector system incorporating the Reticon RL1024S photodiode array has been constructed as part of a double spectrograph to be used to study the earth's atmosphere from ground-based and aircraft-based platforms. To determine accurately the abundances of atmospheric trace gases, this new system must be able to measure spectral absorptions as small as 0.02 percent. The detector exhibits superior signal-to-noise characteristics at the light levels characteristic of scattered skylights, but interference in the passivating layer causes problems in achieving the required precision. The mechanism of the problems and the solution implemented are described in detail.

  20. Reproductive effects in hybrid sparrow from a polluted area in Tunisia: Oxidative damage and altered testicular histomorphology.

    PubMed

    Amri, Nahed; Hammouda, Abdessalem; Rahmouni, Fatma; Chokri, Med Ali; Chaabane, Rim; Selmi, Slaheddine; Rebai, Tarek; Badraoui, Riadh

    2016-07-01

    Air pollution is a threat for human health and wildlife. The aim of this study is to assess the pathophysiological changes and the oxidative-antioxidative status in testicular tissues of 40 Hybrid sparrows collected from four areas in Gabès city, one of the most polluted areas in Tunisia. The testis histopathological analysis revealed alterations in birds from Ghannouche, the polluted area. The thiobarbituric acid reactive substance (TBARS) levels were higher in testis of birds from the contaminated site compared to less polluted areas indicating oxidative damage to membrane lipids. Antioxidant enzyme activities (superoxide dismutase and catalase) were lower in testis sparrows from the polluted site compared with the reference site, suggesting deficiency of the antioxidant system to compensate for oxidative stress. Overall, our results suggest that the hybrid sparrow offers a suitable model for biomonitoring programs of atmosphere pollutants and the selected biomarkers could be useful tool to evaluate pollution impacts in living organisms. PMID:27039245

  1. A hybrid modeling approach to resolve pollutant concentrations in an urban area

    NASA Astrophysics Data System (ADS)

    Stein, Ariel F.; Isakov, Vlad; Godowitch, James; Draxler, Roland R.

    A modeling tool that can resolve contributions from individual sources to the urban environment is critical for air-toxics exposure assessments. Air toxics are often chemically reactive and may have background concentrations originated from distant sources. Grid models are the best-suited tools to handle the regional features of these chemicals. However, these models are not designed to resolve pollutant concentrations on local scales. Moreover, for many species of interest, having reaction time scales that are longer than the travel time across an urban area, chemical reactions can be ignored in describing local dispersion from strong individual sources making Lagrangian and plume-dispersion models practical. In this study, we test the feasibility of developing an urban hybrid simulation system. In this combination, the Community Multi-scale Air Quality model (CMAQ) provides the regional background concentrations and urban-scale photochemistry, and local models such as Hybrid Single Particle Lagrangian Integrated Trajectory model (HYSPLIT) and AMS/EPA Regulatory Model (AERMOD) provide the more spatially resolved concentrations due to local emission sources. In the initial application, the HYSPLIT, AERMOD, and CMAQ models are used in combination to calculate high-resolution benzene concentrations in the Houston area. The study period is from 18 August to 4 September of 2000. The Mesoscale Model 5 (MM5) is used to create meteorological fields with a horizontal resolution of 1×1 km 2. In another variation to this approach, multiple HYSPLIT simulations are used to create a concentration ensemble to estimate the contribution to the concentration variability from point sources. HYSPLIT simulations are used to model two sources of concentration variability; one due to variability created by different particle trajectory pathways in the turbulent atmosphere and the other due to different flow regimes that might be introduced when using gridded data to represent

  2. A cooled avalanche photodiode with high photon detection probability

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Metscher, B. D.

    1986-01-01

    An avalanche photodiode has been operated as a photon-counting detector with 2 to 3 times the sensitivity of currently-available photomultiplier tubes. APD (avalanche photodiodes) detection probabilities that exceed 27% and approach 50% have been measured at an optimum operating temperature which minimizes noise. The sources of noise and their dependence on operating temperature and bias voltage are discussed.

  3. Analytical modeling for gamma radiation damage on silicon photodiodes

    NASA Astrophysics Data System (ADS)

    Jafari, H.; Feghhi, S. A. H.

    2016-04-01

    Radiation-induced damage in PIN silicon photodiode induces degradation of the photodiode parameters. In this work, by presenting an analytical model, the effect of gamma dose on the dark current in a PIN photodiode array was investigated. Geant4 was used to obtain the damage constant as a result of primary incident particle fluence and NIEL distribution calculations. Experimental measurements as well as numerical simulation of the semiconductor with ATLAS were carried out to verify and parameterize the analytical model calculations. A reasonable agreement has been found between analytical results and experimental data for BPX65 silicon photodiodes irradiated by a Co-60 gamma source at total doses up to 500 krad under different reverse voltages. Moreover, the results showed that the dark current of each photodiode array pixel has considerably increased by gamma dose irradiation.

  4. Wedge hybrid plasmonic THz waveguide with long propagation length and ultra-small deep-subwavelength mode area

    PubMed Central

    Gui, Chengcheng; Wang, Jian

    2015-01-01

    We present a novel design of wedge hybrid plasmonic terahertz (THz) waveguide consisting of a silicon (Si) nanowire cylinder above a triangular gold wedge with surrounded high-density polyethylene as cladding. It features long propagation length and ultra-small deep-subwavelength mode confinement. The mode properties of wedge hybrid plasmonic THz waveguide are comprehensively characterized in terms of propagation length (L), normalized mode area (Aeff /A0), figure of merit (FoM), and chromatic dispersion (D). The designed wedge hybrid plasmonic THz waveguide enables an ultra-small deep-subwavelength mode area which is more than one-order of magnitude smaller compared to previous rectangular one. When choosing the diameter of Si nanowire cylinder, a smaller diameter (e.g. 10 μm) is preferred to achieve longer L and higher FoM, while a larger diameter (e.g. 60 μm) is favorable to obtain smaller Aeff /A0 and higher FoM. We further study the impacts of possible practical fabrication errors on the mode properties. The simulated results of propagation length and normalized mode area show that the proposed wedge hybrid plasmonic THz waveguide is tolerant to practical fabrication errors in geometry parameters such as misalignment in the horizontal direction, variation of wedge tip angle, and variation of wedge tip curvature radius. PMID:26155782

  5. Wedge hybrid plasmonic THz waveguide with long propagation length and ultra-small deep-subwavelength mode area.

    PubMed

    Gui, Chengcheng; Wang, Jian

    2015-01-01

    We present a novel design of wedge hybrid plasmonic terahertz (THz) waveguide consisting of a silicon (Si) nanowire cylinder above a triangular gold wedge with surrounded high-density polyethylene as cladding. It features long propagation length and ultra-small deep-subwavelength mode confinement. The mode properties of wedge hybrid plasmonic THz waveguide are comprehensively characterized in terms of propagation length (L), normalized mode area (Aeff/A0), figure of merit (FoM), and chromatic dispersion (D). The designed wedge hybrid plasmonic THz waveguide enables an ultra-small deep-subwavelength mode area which is more than one-order of magnitude smaller compared to previous rectangular one. When choosing the diameter of Si nanowire cylinder, a smaller diameter (e.g. 10 μm) is preferred to achieve longer L and higher FoM, while a larger diameter (e.g. 60 μm) is favorable to obtain smaller Aeff/A0 and higher FoM. We further study the impacts of possible practical fabrication errors on the mode properties. The simulated results of propagation length and normalized mode area show that the proposed wedge hybrid plasmonic THz waveguide is tolerant to practical fabrication errors in geometry parameters such as misalignment in the horizontal direction, variation of wedge tip angle, and variation of wedge tip curvature radius. PMID:26155782

  6. Examining the area effect for parasite communities of bluegill x green sunfish hybrids in five constructed ponds in Kansas.

    PubMed

    Zelmer, Derek A; Campbell, Johnathon K

    2011-04-01

    The parasite communities of bluegill x green sunfish hybrids were examined from 5 constructed ponds in Kansas in an attempt to evaluate the separate effects of habitat area and habitat heterogeneity on parasite community structure. Characterization of fish community structure and collection of hybrid fishes was conducted using an electrofishing boat. Benthic invertebrates were sampled, and substrate types examined at 30 evenly spaced points in each pond. Nonmetric multidimensional scaling of the parasite infracommunities, in concert with an analysis of similarities, indicated significant clustering of infracommunities by locality. The number and diversity of habitat types, and the richness and diversity of both fishes and benthic invertebrates, were positively correlated with the first axis of the infracommunity ordination. Pond surface area, parasite richness, and stocking pressure were negatively correlated with the first axis of the infracommunity ordination, suggesting that pond area, stocking pressure, or both was a stronger determinant of parasite community structure in these systems than habitat and host heterogeneity. PMID:21506793

  7. Improvement in the quantum sensitivity of InAs/InAsSb/InAsSbP heterostructure photodiodes

    SciTech Connect

    Imenkov, A. N.; Grebenshchikova, E. A. Starostenko, D. A.; Sherstnev, V. V.; Konovalov, G. G.; Andreev, I. A.; Yakovlev, Yu. P.

    2013-05-15

    InAs/InAs{sub 0.88}Sb{sub 0.12}/InAs{sub 0.50}Sb{sub 0.20}P{sub 0.30} heterostructure photodiodes operating at room temperature in the spectral range 1-4.8 {mu}m are developed. It is shown that the formation of a curvilinear reflecting surface constituted by a number of hemispheres on the rearside of the photodiode chip leads to an increase in the quantum sensitivity of the photodiodes by a factor of 1.5-1.7 at wavelengths in the range 2.2-4.8 {mu}m. At an exposed photodiode area of 0.9 mm{sup 2} and a p-n junction area of 0.15 mm{sup 2}, a zero-bias differential resistance of 30 {Omega} and a quantum sensitivity of 0.24 electron/photon at a wavelength of 3 {mu}m are obtained. The operation of a photodiode with re-reflection of the photon flux in the crystal due to reflection from the curvilinear surface of the rearside of the photodiode chip is theoretically analyzed. The possibility of effective conversion of the re-reflected flux of photons into a photocurrent, with a simultaneous decrease in the p-n junction area, is demonstrated. An increase in the quantum sensitivity in the short-wavelength spectral range 1-2.2 {mu}m by 35% relative to the calculated data is observed, which is probably due to impact ionization in the narrow-gap active region.

  8. Diamond photodiodes for x-ray application

    SciTech Connect

    Distel, James R; Smedley, John; Keister, Jeffrey W; Muller, Erik; Jordan - Sweet, Jean; Bohon, Jen; Dong, Bin

    2009-01-01

    Single crystal high purity CVD diamonds have been metallized and calibrated as photodiodes at the National Synchrotron Light Source (NSLS). Current mode responsivity measurements have been made over a wide range (0.2-28 keV) of photon energies across several beamlines. Linear response has been achieved over ten orders of magnitude of incident flux, along with uniform spatial response. A simple model of responsivity has been used to describe the results, yielding a value of 13.3 {+-} 0.5 eV for the mean pair creation energy. The responsivity vs. photon energy data show a dip for photon energies near the carbon edge (284 eV), indicating incomplete charge collection for carriers created less than one micron from the metallized layer.

  9. Characterization of avalanche photodiodes for lidar atmospheric return signal detectors

    NASA Technical Reports Server (NTRS)

    Antill, C. W., Jr.; Holloway, R. M.

    1988-01-01

    Results are presented from tests to characterize noise, dark current, overload, and gain versus bias, relationships of ten avalanche photodiodes. The advantages of avalanche photodiodes over photomultiplier tubes for given laser wavelengths and return signal amplitudes are outlined. The relationship between responsivity and temperature and dark current and temperature are examined. Also, measurements of the noise equivalent power, the excess noise factor, and linearity are given. The advantages of using avalanche photodiodes in the Lidar Atmospheric Sensing Experiment and the Lidar In-Space Technology Experiment are discussed.

  10. CMOS array of photodiodes with electronic processing for 3D optical reconstruction

    NASA Astrophysics Data System (ADS)

    Hornero, Gemma; Montane, Enric; Chapinal, Genis; Moreno, Mauricio; Herms, Atila

    2001-04-01

    It is well known that laser time-of-flight (TOF) and optical triangulation are the most useful optical techniques for distance measurements. The first one is more suitable for large distances, since for short range of distances high modulation frequencies of laser diodes (©200-500MHz) are needed. For these ranges, optical triangulation is simpler, as it is only necessary to read the projection of the laser point over a linear optical sensor without any laser modulation. Laser triangulation is based on the rotation of the object. This motion shifts the projected point over the linear sensor, resulting on 3D information, by means of the whole readout of the linear sensor in each angle position. On the other hand, a hybrid method of triangulation and TOF can be implemented. In this case, a synchronized scanning of a laser beam over the object results in different arrival times of light to each pixel. The 3D information is carried by these delays. Only a single readout of the linear sensor is needed. In this work we present the design of two different linear arrays of photodiodes in CMOS technology, the first one based on the Optical triangulation measurement and the second one based in this hybrid method (TFO). In contrast to PSD (Position Sensitive Device) and CCDs, CMOS technology can include, on the same chip, photodiodes, control and processing electronics, that in the other cases should be implemented with external microcontrollers.

  11. Impact of post-metallization annealing on Ge-on-Si photodiodes passivated with silicon dioxide

    NASA Astrophysics Data System (ADS)

    DiLello, Nicole A.; Hoyt, Judy L.

    2011-07-01

    Ge-on-Si photodiodes were fabricated from epitaxial germanium films grown by low-pressure chemical vapor deposition. These vertical p-i-n diodes were passivated with SiO2 deposited by chemical vapor deposition. It is found that the incorporation of a post-metallization anneal reduces the dark current by 1000X for small-area devices, with 10 × 10 μm diodes exhibiting a dark current of 8 nA at -1 V. Metal-oxide-semiconductor capacitors were also fabricated using the same materials and annealing conditions. Capacitance-voltage measurements indicate that the anneal changes the surface condition of the germanium from depletion to accumulation, lowering the photodiode perimeter leakage current.

  12. Wet etching and chemical polishing of InAs/GaSb superlattice photodiodes

    NASA Astrophysics Data System (ADS)

    Chaghi, R.; Cervera, C.; Aït-Kaci, H.; Grech, P.; Rodriguez, J. B.; Christol, P.

    2009-06-01

    In this paper, we studied wet chemical etching fabrication of the InAs/GaSb superlattice mesa photodiode for the mid-infrared region. The details of the wet chemical etchants used for the device process are presented. The etching solution is based on orthophosphoric acid (H3PO4), citric acid (C6H8O7) and H2O2, followed by chemical polishing with the sodium hypochlorite (NaClO) solution and protection with photoresist polymerized. The photodiode performance is evaluated by current-voltage measurements. The zero-bias resistance area product R0A above 4 × 105 Ω cm2 at 77 K is reported. The device did not show dark current degradation at 77 K after exposition during 3 weeks to the ambient air.

  13. Characterization of Al0.8Ga0.2As geiger photodiode

    NASA Astrophysics Data System (ADS)

    Chen, X. J.; Ren, Min; Chen, Yaojia; Johnson, E. B.; Campbell, Joe C.; Christian, James F.

    2015-08-01

    Solid-state photomultipliers (SSPM) are high gain photodetectors composed of Geiger photodiodes (GPD) operating above device breakdown voltage. In scintillation based radiation detection applications, SSPMs fabricated using silicon (SiPMs, MPPCs, etc) provide a compact, low cost alternative to photomultiplier tubes (PMTs), however, the high dark count rate due to its low band-gap (1.1eV) limits the signal-to-noise performance as the silicon SSPM is scaled to large areas. SSPMs fabricated in materials with a larger band-gap have the potential to surmount the performance limitations experienced by silicon. AlGaAs is a material that provides a bandgap from 1.55eV to 2.13 eV, depending on Al concentration. Using high Al concentration AlGaAs to engineer a wideband- gap (>2eV) SSPM is very desirable in terms of reducing dark noise, which promises better signal-to-noise performances when large detector areas is needed. This work describes the development of Geiger photodiodes (GPDs), the individual elements of a SSPM, fabricated in AlGaAs with 80% Al concentration. We present the design of the GPDs, the fabrication process, along with characterization data of fabricated GPD samples. To the best of our knowledge, we have demonstrated for the first time, a passively quenched Geiger photodiode in Al0.8Ga0.2As.

  14. Fully tileable photodiode matrix for medical imaging by using through-wafer interconnects

    NASA Astrophysics Data System (ADS)

    Juntunen, Mikko; Ji, Fan; Henttinen, Kimmo; Luusua, Ismo; Hietanen, Iiro; Eränen, Simo

    2007-10-01

    This paper presents a technology for a fully tileable two-dimensional (2D) photodiode matrix for medical imaging, specifically X-ray computed tomography (CT). A key trend in the CT industry is to build machines with larger area detector to speed up the measurements and to avoid image blurring due to patient movement during scanning. In current CT detector constructions, a major limiting factor in providing more detector coverage is the need to read out the signals from the individual photo-detector elements of the detector array through lines along the surface facing the radiation source and wire bonds down to a substrate or to an electronics chip. Using this method, there is a physical limitation on the size of a photo-detector array that may be manufactured. A photo-detector with the possibility of expansion in all directions is known as a 'tileable' detector. A technology of integrating through-wafer interconnects (TWIs) with traditional front illuminated photodiodes is introduced. Photocurrent can be read out from back side of the photodiode chip through interconnects, giving possibility of constructing arbitrarily large area of photo-detector for CT machine. Results of a sample 2D demonstrator detector array are presented showing that the requirements of modern CT systems can be met.

  15. Modular design for narrow scintillating cells with MRS photodiodes in strong magnetic field for ILC detector

    NASA Astrophysics Data System (ADS)

    Beznosko, D.; Blazey, G.; Dyshkant, A.; Rykalin, V.; Schellpffer, J.; Zutshi, V.

    2006-08-01

    The experimental results for the narrow scintillating elements with effective area about 20 cm 2 are reported. The elements were formed from the single piece of scintillator and were read out via wavelength shifting (WLS) fibers with the Metal/Resistor/Semiconductor (MRS) photodiodes on both ends of each fiber. The count rates were obtained using radioactive source 90Sr, with threshold at about three photoelectrons in each channel and quad coincidences (double coincidences between sensors on each fiber and double coincidences between two neighboring fibers). The formation of the cells from the piece of scintillator by using grooves is discussed, and their performances were tested using the radioactive source by measuring the photomutiplier current using the same WLS fiber. Because effective cell area can be readily enlarged or reduced, this module may be used as an active element for calorimeter or muon system for the design of the future electron-positron linear collider detector. Experimental verification of the performance of the MRS photodiode in a strong magnetic field of 9 T, and the impact a magnet quench at 9.5 T are reported. The measurement method used is described. The results confirm the expectations that the MRS photodiode is insensitive to a strong magnetic field and therefore applicable to calorimetry in the presence of magnetic field. The overall result is of high importance for large multi-channel systems.

  16. A novel pixel design with hybrid type isolation scheme for low dark current in CMOS image sensor

    NASA Astrophysics Data System (ADS)

    Choi, Sung Ho; Kim, Yi Tae; Oh, Min Seok; Park, Young Hwan; Cho, Jeong Jin; Jang, Young Heub; Han, Hyung Jun; Choi, Jong Won; Park, Ho Woo; Jung, Sang Il; Oh, Hoon Sang; Ahn, Jung Chak; Goto, Hiroshige; Choi, Chi Young; Roh, Yonghan

    2013-02-01

    New isolation scheme for CMOS image sensor pixel is proposed and its improved dark current performance is reported. It is well known that shallow trench isolation (STI) is one of major sources of dark current in imager pixel due to the existence of interfacial defects at STI/Si interface. On the account STI-free structure over the whole pixel area was previously reported for reducing dark current. As the size of pixel pitch is shrunk, however, it becomes increasingly difficult to isolate in-pixel transistors electrically without STI. In this work, we implemented hybrid type isolation scheme of removing STI around photodiode to suppress the dark current and remaining STI near transistors to guarantee the electrical isolation of transistors in pixel. It was successfully achieved that the dark current was significantly reduced by removing the STI around the photodiode together with normal operation of in-pixel transistors.

  17. Stable, high quantum efficiency silicon photodiodes for vacuum-UV applications

    NASA Technical Reports Server (NTRS)

    Korde, Raj; Canfield, L. Randall; Wallis, Brad

    1988-01-01

    Silicon photodiodes have been developed by defect-free phosphorus diffusion having practically no carrier recombination at the SiSiO2 interface or in the front diffused region. The quantum efficiency of these photodiodes was found to be around 120 percent at 100 nm. Unlike the previously tested silicon photodiodes, the developed photodiodes exhibit extremely stable quantum efficiency over extended periods of time. The possibility of using these photodiodes as vacuum ultraviolet detector standards is being currently investigated.

  18. Relative degradation of near infrared avalanche photodiodes from proton irradiation

    NASA Technical Reports Server (NTRS)

    Becker, Heidi; Johnston, Allan H.

    2004-01-01

    InGaAs and Ge avalanche photodiodes are compared for the effects of 63-MeV protons on dark current. Differences in displacement damage factors are discussed as they relate to structural differences between devices.

  19. Optimum Receiver Structure for PPM Signals with Avalanche Photodiode Statistics

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V.; Srinivasan, M.

    1998-01-01

    The maximum likelihood decision statistic for detection of pulse-position modulated signals with an avalanche photodiode is derived, using the more accurate Webb density rather than Poisson or Gaussian approximations for the distribution of avalanche photodiode output electrons. It is shown that for Webb-distributed output electtrons, the maximum likelihood rule is to choose the PPM word corresponding to the slot with the maximum electron count.

  20. Presumable incipient hybrid speciation of door snails in previously glaciated areas in the Caucasus.

    PubMed

    Koch, Eva L; Neiber, Marco T; Walther, Frank; Hausdorf, Bernhard

    2016-04-01

    Homoploid hybrid speciation, speciation by hybridization without a change in chromosome number, may be the result of an encounter of closely related species in a habitat that is different from that usually occupied by these species. In the northwestern Caucasus the land snail species Micropontica caucasica and M. circassica form two distinct entities with little admixture at low and intermediate altitudes. However, at higher altitudes in the Lagonaki plateau, which were repeatedly glaciated, Micropontica populations with intermediate characters occur. Admixture analyses based on AFLP data demonstrated that the populations from the Lagonaki plateau are homoploid hybrids that now form a cluster separate from the parental species. The Lagonaki populations are characterized by a mtDNA haplotype clade that has been found in the parental species only once. The fixation of this haplotype clade in most hybrid populations suggests that these haplotypes are better adapted to the cooler conditions in high altitude habitats and have replaced the haplotypes of the parental species in a selective sweep. The fixation of a presumably adaptive mitochondrial haplotype clade in the Lagonaki populations is an important step towards speciation under the differential fitness species concept. PMID:26748267

  1. Measuring atmospheric dispersion employing avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Schreiber, Ulrich; Maier, Wolfgang; Riepl, Stefan

    1994-12-01

    The accuracy of today's satellite laser ranging system is limited to a few cm. A significant part of this range error is due to the limitations of the atmospheric correction model. A dual color ranging experiment has been designed to investigate this source of error. When ranging to satellites at the fundamental and second harmonic frequency of a Nd:YAG laser, two different pulse round trip times are obtained simultaneously. The infrared pulse is detected by an avalanche photodiode, operated in the `Geiger mode', while the green pulse is recorded by a microchannel plate photomultiplier. For a given satellite pass, the jitter in recording the time of flight of the pulse is too high to calculate an atmospheric correction from individual measurements. Due to the many shots per satellite pass, the scatter can be significantly reduced by applying a nonlinear least squares fitting procedure to the data. The results of a large number of satellite passes are compared with the predictions of the Marini-Murray model.

  2. Technology reinvestment project`s focus area: Electric and hybrid tactical and commercial vehicles

    SciTech Connect

    1994-11-01

    The publication contains the transparencies from the Technology Reinvestment Projects`s (TRP`s) workshops held in Chicago, IL and Austin, TX in November, 1994. It includes general sessions on TRP, Technology Development, Regional Technology Alliances, and Manufacturing Education and Training, as well as the break out session on Electric and Hybrid Tactical and Commercial Vehicles. Also included are registration forms for both workshops.

  3. [Wastewater Quantity and Quality Fluctuation Characteristics of Typical Area of Hybrid Sewage System].

    PubMed

    Cheng, Xun; Zhang, Ming-kai; Liu, Yan-chen; Shi, Han-chang

    2016-05-15

    The inflow and infiltration problems cause large fluctuation in wastewater quantity and quality in hybrid sewage system. This seriously challenges the operation and management of sewage system. A multi-point on-line simultaneous monitoring system was established in a typical hybrid sewage system. The key characteristic parameters and their variation features under different circumstances were studied. The result indicated that the daily variation rule was obvious and appeared synchronous among multiple points at normal water level under dry weather flow, but there was no synchronization in conductivity variation among multiple points at high water level under dry weather flow. The statistical distribution range of water level and conductivity was significantly impacted by the seasonal rainfall change under dry weather. The statistical distribution ranges of water level variation rate and conductivity variation rate in specific time were significantly impacted by the rainfall. The response features of water level and conductivity to rainfall intensity and pattern were significantly different under different circumstances. The response sensitivity of conductivity was higher than water level at normal water level and lower at high water level. The database which could support the optimization of operation and management in the hybrid sewage system was proposed based on the distribution law of wastewater quality and quantity fluctuation under dry and wet weather, as well as the variation rate features of wastewater quality and quantity during rainfall obtained using the multi-point on-line simultaneous monitoring system. PMID:27506039

  4. Metropolitian area network services comprised of virtual local area networks running over hybrid fiber-coax and asynchronous transfer mode technologies

    NASA Astrophysics Data System (ADS)

    Biedron, William S.

    1995-11-01

    Since 1990 there has been a rapid increase in the demand for communication services, especially local and wide area network (LAN/WAN) oriented services. With the introduction of the DFB laser transmitter, hybrid-fiber-coax (HFC) cable plant designs, ATM transport technologies and rf modems, new LAN/WAN services can now be defined and marketed to residential and business customers over existing cable TV systems. The term metropolitan area network (MAN) can be used to describe this overall network. This paper discusses the technical components needed to provision these services as well as provides some perspectives on integration issues. Architecture at the headend and in the backbone is discussed, as well as specific service definitions and the technology issues associated with each. The TCP/IP protocol is suggested as a primary protocol to be used throughout the MAN.

  5. Rapid production of large-area deep sub-wavelength hybrid structures by femtosecond laser light-field tailoring

    SciTech Connect

    Wang, Lei; Chen, Qi-Dai E-mail: hbsun@jlu.edu.cn; Yang, Rui; Xu, Bin-Bin; Wang, Hai-Yu; Yang, Hai; Huo, Cheng-Song; Tu, Hai-Ling; Sun, Hong-Bo E-mail: hbsun@jlu.edu.cn

    2014-01-20

    The goal of creation of large-area deep sub-wavelength nanostructures by femtosecond laser irradiation onto various materials is being hindered by the limited coherence length. Here, we report solution of the problem by light field tailoring of the incident beam with a phase mask, which serves generation of wavelets. Direct interference between the wavelets, here the first-order diffracted beams, and interference between a wavelet and its induced waves such as surface plasmon polariton are responsible for creation of microgratings and superimposed nanogratings, respectively. The principle of wavelets interference enables extension of uniformly induced hybrid structures containing deep sub-wavelength nanofeatures to macro-dimension.

  6. Photodiode arrays having minimized cross-talk between diodes

    DOEpatents

    Guckel, Henry; McNamara, Shamus P.

    2000-10-17

    Photodiode arrays are formed with close diode-to-diode spacing and minimized cross-talk between diodes in the array by isolating the diodes from one another with trenches that are formed between the photodiodes in the array. The photodiodes are formed of spaced regions in a base layer, each spaced region having an impurity type opposite to that of the base layer to define a p-n junction between the spaced regions and the base layer. The base layer meets a substrate at a boundary, with the substrate being much more heavily doped than the base layer with the same impurity type. The trenches extend through the base layer and preferably into the substrate. Minority carriers generated by absorption of light photons in the base layer can only migrate to an adjacent photodiode through the substrate. The lifetime and the corresponding diffusion length of the minority carriers in the substrate is very short so that all minority carriers recombine in the substrate before reaching an adjacent photodiode.

  7. Photocurrent enhancement of HgTe quantum dot photodiodes by plasmonic gold nanorod structures.

    PubMed

    Chen, Mengyu; Shao, Lei; Kershaw, Stephen V; Yu, Hui; Wang, Jianfang; Rogach, Andrey L; Zhao, Ni

    2014-08-26

    The near-field effects of noble metal nanoparticles can be utilized to enhance the performance of inorganic/organic photosensing devices, such as solar cells and photodetectors. In this work, we developed a well-controlled fabrication strategy to incorporate Au nanostructures into HgTe quantum dot (QD)/ZnO heterojunction photodiode photodetectors. Through an electrostatic immobilization and dry transfer protocol, a layer of Au nanorods with uniform distribution and controllable density is embedded at different depths in the ZnO layer for systematic comparison. More than 80 and 240% increments of average short-circuit current density (Jsc) are observed in the devices with Au nanorods covered by ∼7.5 and ∼4.5 nm ZnO layers, respectively. A periodic finite-difference time-domain (FDTD) simulation model is developed to analyze the depth-dependent property and confirm the mechanism of plasmon-enhanced light absorption in the QD layer. The wavelength-dependent external quantum efficiency spectra suggest that the exciton dissociation and charge extraction efficiencies are also enhanced by the Au nanorods, likely due to local electric field effects. The photodetection performance of the photodiodes is characterized, and the results show that the plasmonic structure improves the overall infrared detectivity of the HgTe QD photodetectors without affecting their temporal response. Our fabrication strategy and theoretical and experimental findings provide useful insight into the applications of metal nanostructures to enhance the performance of organic/inorganic hybrid optoelectronic devices. PMID:25020202

  8. Quantifying the Area-at-Risk in Reperfused STEMI Patients Using Hybrid Cardiac PET-MR Imaging

    PubMed Central

    Bulluck, Heerajnarain; White, Steven K.; Fröhlich, Georg M.; Casson, Steven G.; O’Meara, Celia; Newton, Ayla; Nicholas, Jennifer; Weale, Peter; Wan, Simon M.Y.; Sirker, Alex; Moon, James C.; Yellon, Derek M.; Groves, Ashley; Menezes, Leon; Hausenloy, Derek J

    2016-01-01

    Background Hybrid Positron Emission Tomography and Magnetic Resonance (PET-MR) allows the advantages of MR in tissue characterizing the myocardium to be combined with the unique metabolic insights of PET. We hypothesized that the area of reduced myocardial glucose uptake would closely match the area-at-risk (AAR) delineated by T2-mapping in ST-segment elevation myocardial infarction (STEMI) patients. Methods and Results Hybrid PET-MR using 18F-fluorodeoxyglucose (FDG) for glucose uptake was performed in 21 STEMI patients at a median of 5 days. Follow-up scans were performed in a subset of patients 12 months later. The area of reduced FDG uptake was significantly larger than the infarct size quantified by late gadolinium enhancement (LGE) (37.2±11.6% versus 22.3±11.7%; P<0.001), and closely matched the AAR by T2-mapping (37.2±11.6% versus 36.3±12.2%; P=0.10, R 0.98, bias 0.9±4.4%). On the follow-up scans, the area of reduced FDG uptake was significantly smaller in size when compared to the acute scans (19.5 [6.3-31.8]% versus 44.0 [21.3-55.3]%, P=0.002), and closely correlated with the areas of LGE (R 0.98) with a small bias of 2.0±5.6%. An FDG uptake of ≥45% on the acute scans could predict viable myocardium on the follow-up scan. Both transmural extent of LGE and FDG uptake on the acute scan performed equally well to predict segmental wall motion recovery. Conclusions Hybrid PET-MR in the reperfused STEMI patient showed reduced myocardial glucose uptake within the AAR and closely matched the AAR delineated by T2-mapping. FDG uptake, as well as transmural extent of LGE acutely can identify viable myocardial segments. PMID:26926269

  9. Design of an Area-Efficient and Low-Power NoC Architecture Using a Hybrid Network Topology

    NASA Astrophysics Data System (ADS)

    Kim, Woo Joo; Hwang, Sun Young

    This paper proposes a novel hybrid NoC structure and a dynamic job distribution algorithm which can reduce system area and power consumption by reducing packet drop rate for various multimedia applications. The proposed NoC adopts different network structures between sub-clusters. Network structure is determined by profiling application program so that packet drop rate can be minimized. The proposed job distribution algorithm assigns every job to the sub-cluster where packet drop rate can be minimized for each multimedia application program. The proposed scheme targets multimedia applications frequently used in modern embedded systems, such as MPEG4 and MP3 decoders, GPS positioning systems, and OFDM demodulators. Experimental results show that packet drop rate was reduced by 31.6% on the average, when compared to complex network structure topologies consisting of sub-clusters of same topology. Chip area and power consumption were reduced by 16.0% and 34.0%, respectively.

  10. Analysis of the photodiode boundary layer transition indicator

    SciTech Connect

    Kuntz, D.W.; Wilken, A.C.; Payne, J.L.

    1994-01-01

    The photodiode transition indicator is a device which has been successfully used to determine the onset of boundary layer transition on numerous hypersonic flight vehicles. The exact source of the electromagnetic radiation detected by the photodiode at transition was not understood. In some cases early saturation of the device occurred, and the device failed to detect transition. Analyses have been performed to determine the source of the radiation producing the photodiode signal. The results of these analyses indicate that the most likely source of the radiation is blackbody emission from the heatshield material bordering the quartz window of the device. Good agreement between flight data and calculations based on this radiation source has been obtained. Analyses also indicate that the most probable source of the radiation causing early saturation is blackbody radiation from carbon particles which break away from the nosetip during the ablation process.

  11. Photonic microwave generation with high-power photodiodes.

    PubMed

    Fortier, Tara M; Quinlan, Franklyn; Hati, Archita; Nelson, Craig; Taylor, Jennifer A; Fu, Yang; Campbell, Joe; Diddams, Scott A

    2013-05-15

    We utilized and characterized high-power, high-linearity modified unitraveling carrier (MUTC) photodiodes for low-phase-noise photonic microwave generation based on optical frequency division (OFD). When illuminated with picosecond pulses from a repetition-rate-multiplied gigahertz Ti:sapphire modelocked laser, the photodiodes can achieve a 10 GHz signal power of +14 dBm. Using these diodes, we generated a 10 GHz microwave tone with less than 500 attoseconds absolute integrated timing jitter (1 Hz-10 MHz) and a phase noise floor of -177 dBc/Hz.We also characterized the electrical response, amplitude-to-phase conversion, saturation, and residual noise of the MUTC photodiodes. PMID:23938920

  12. III-V alloy heterostructure high speed avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Law, H. D.; Nakano, K.; Tomasetta, L. R.

    1979-01-01

    Heterostructure avalanche photodiodes have been successfully fabricated in several III-V alloy systems: GaAlAs/GaAs, GaAlSb/GaAlSb, and InGaAsP/InP. These diodes cover optical wavelengths from 0.4 to 1.8 micron. Early stages of development show very encouraging results. High speed response of less than 35 ps and high quantum efficiency more than 95 percent have been obtained. The dark currents and the excess avalanche noise are also dicussed. A direct comparison of GaAlSb, GaAlAsSb, and In GaAsP avalanche photodiodes is given.

  13. Effects of the 9-T magnetic field on MRS photodiode

    SciTech Connect

    Beznosko, D.; Blazey, G.; Dyshkant, A.; Rykalin, V.; /Northern Illinois U.

    2005-10-01

    The experimental results on the performance of the MRS (Metal/Resistor/Semiconductor) photodiode in the strong magnetic field of 9T, and the possible impact of the quench of the magnet at 9.5T on sensor's operation are reported. The measurement method used is being described. The results of the work agree with the expectations that the MRS photodiode is not exhibiting sensitivity to the magnetic field presence. This result is essential for the design of the future electron-positron linear collider detector.

  14. Study on avalanche photodiode influence on heterodyne laser interferometer linearity

    NASA Astrophysics Data System (ADS)

    Budzyn, Grzegorz; Podzorny, Tomasz

    2016-06-01

    In the paper we analyze factors reducing the possible accuracy of the heterodyne laser interferometers. The analysis is performed for the avalanche-photodiode input stages but is in main points valid also for stages with other type of photodetectors. Instrumental error originating from optical, electronic and digital signal processing factors is taken into consideration. We stress factors which are critical and those which can be neglected at certain accuracy requirements. In the work we prove that it is possible to reduce errors of the laser instrument below 1 nm point for multiaxial APD based interferometers by precise control of incident optical power and the temperature of the photodiode.

  15. High speed, high performance /Hg,Cd/Te photodiode detectors.

    NASA Technical Reports Server (NTRS)

    Soderman, D. A.; Pinkston, W. H.

    1972-01-01

    The current performance of high speed photodiode detectors for the 1 to 10 micron spectral region is discussed. The (Hg,Cd)Te photodiode configuration, detector properties, integration in laser receiver modules, and frequency response are considered for near infrared and far infrared wavelengths. The recent advances in (Hg,Cd)Te material and device development are indicated by the realization not only of exceptionally high speed detectors but of detectors that exhibit excellent detectivities. The performance improves substantially when the detector is cooled. This detector junction technology has been extended to other compositions of (Hg,Cd)Te for peak spectral responses at 5 and 10 micron.

  16. Ultra-low noise charge sensitive preamplifier for scintillation detection with avalanche photodiodes in PET applications

    SciTech Connect

    Schmitt, D.; Lecomte, R.; Lapointe, M.; Martel, G.; Carrier, C.; Karuta, B.; Duval, F.

    1987-02-01

    The need for compact, fast, low-noise front-end electronics in high resolution positron emission tomography (PET) has prompted this effort to design a preamplifier suitable for avalanche photodiode-based scintillation detectors. Due to the small signals from the detectors (< .03 rhoC/meV), a preamplifier with ultra-low noise performance in the 5 to 20 MHz range is essential to achieve the timing resolution required by the PET application. Out of many available technologies, a new third generation MOSFET was selected and implemented as input transistor in an original charge sensitive (CSP) design. Performance among the best reported to date are obtained. The new design was implemented as a dual-channel preamplifier in high density hybrid (thick film) technology.

  17. PbS colloidal quantum dot photodiodes for low-cost SWIR sensing

    NASA Astrophysics Data System (ADS)

    Klem, Ethan J. D.; Gregory, Chris; Temple, Dorota; Lewis, Jay

    2015-06-01

    RTI has developed a photodiode technology based on solution-processed PbS colloidal quantum dots (CQD). These devices are capable of providing low-cost, high performance detection across the Vis-SWIR spectral range. At the core of this technology is a heterojunction diode structure fabricated using techniques well suited to wafer-scale fabrication, such as spin coating and thermal evaporation. This enables RTI's CQD diodes to be processed at room temperature directly on top of read-out integrated circuits (ROIC), without the need for the hybridization step required by traditional SWIR detectors. Additionally, the CQD diodes can be fabricated on ROICs designed for other detector material systems, effectively allowing rapid prototype demonstrations of CQD focal plane arrays at low cost and on a wide range of pixel pitches and array sizes.

  18. Performance comparison of CMOS-based photodiodes for high-resolution and high-sensitivity digital mammography

    NASA Astrophysics Data System (ADS)

    Bae, J. H.; Cho, M.; Kim, M. S.; Lee, D. H.; Cho, G.

    2011-12-01

    In order to develop a high-resolution and high-sensitivity digital mamographic detector, to use a commercially-available and well-developed CMOS image sensor (CIS) process can be a cost-effective way. However, in any commercial CIS process, several different types of n- or p-layers can be used so that various pn-junction structures could be formed depending on the choice of n- and p-layer combination. We performed a comparative analysis on the characteristics of three types of photodiodes formed on a high-resistivity p-type epitaxial wafer by applying three available n-layer processes in order to develop the high-sensitivity photodiode for a scintillator-based X-ray imaging detector. As a preliminar study, a small test-version CIS chip with an 80 × 80 pixel array of a 3-transistor active pixel sensor structure, 50 μm pitch and 80{%} fill factor was fabricated. The pixel area is subdivided into four 40 × 40 sub-arrays and 3 different types of photodides are designed for each sub-array by using n+, n- and n-well layers. All other components are designed to be identical for impartial comparison of the photodiodes only. Among 3 types, the n-/p-epi photodiode exhibited high charge-to-voltage gain (0.86 μV/e-), high quantum efficiency (49% at 532 nm wavelength) and low dark current (294 pA/cm2). The test CIS chip was coupled to a phosphor screen, Lanex Fine or Lanex Regular, both composed of Gd2O2S:Tb, and was tested using X-rays in a mammography setting. Among 6 cases, n-/p-epi photodiode coupled with the Lanex Regular also showed the highest sensitivity of 30.5 mV/mR.

  19. Independently accessed back-to-back HgCdTe photodiodes: A new dual-band infrared detector

    NASA Astrophysics Data System (ADS)

    Reine, M. B.; Norton, P. W.; Starr, R.; Weiler, M. H.; Kestigian, M.; Musicant, B. L.; Mitra, P.; Schimert, T.; Case, F. C.; Bhat, Lb.; Ehsani, H.; Rao, V.

    1995-05-01

    We report the first data for a new two-color HgCdTe infrared detector for use in large dual-band infrared focal plane arrays (IRFPAs). Referred to as the independently accessed back-to-back photodiode structure, this novel dual-band HgCdTe detector provides independent electrical access to each of two spatially collocated back-to-back HgCdTe photodiodes so that true simultaneous and independent detection of medium wavelength (MW, 3-5 μm) and long wavelength (LW, 8-12 μm) infrared radiation can be accomplished. This new dual-band detector is directly compatible with standard backside-illuminated bump-interconnected hybrid HgCdTe IRFPA technology. It is capable of high fill factor, and allows high quantum efficiency and BLIP sensitivity to be realized in both the MW and LW photodiodes. We report data that demonstrate experimentally the key features of this new dual-band detector. These arrays have a unit cell size of 100 x 100 μm2, and were fabricated from a four-layer p-n-N-P HgCdTe film grown in situ by metalorganic chemical vapor deposition on a CdZnTe substrate. At 80K, the MW detector cutoff wavelength is 4.5 μm and the LW detector cutoff wavelength is 8.0 μm. Spectral crosstalk is less than 3%. Data confirm that the MW and LW photodiodes are electrically and radiometrically independent.

  20. Hybrid microelectronic technology

    NASA Astrophysics Data System (ADS)

    Moran, P.

    Various areas of hybrid microelectronic technology are discussed. The topics addressed include: basic thick film processing, thick film pastes and substrates, add-on components and attachment methods, thin film processing, and design of thick film hybrid circuits. Also considered are: packaging hybrid circuits, automating the production of hybrid circuits, application of hybrid techniques, customer's view of hybrid technology, and quality control and assurance in hybrid circuit production.

  1. Results on a prototype of a large-area X-ray imaging device using CMOS hybrid detectors

    NASA Astrophysics Data System (ADS)

    Chaput, J.; Caria, M.; Laverroux, F.; Surre, B.; Maublant, J.

    2005-12-01

    This paper presents the first results on a prototype of a large-area X-ray imaging device made out of hybrid CMOS pixel detectors. The challenges of manufacturing and implementing imaging devices on an area larger than the single component size, with a seamless sensitive area, are addressed via a preliminary evaluation of the images. A sensitive area of approximately 6×3 cm 2 was built with eight single ASIC chips performing photon counting and bump-bonded to two high-resistivity p-n silicon sensors working in a reverse bias mode. Each chip consists of 256×256 identical square pixels of 55 μm side. The image delivered is a 1024×512-pixel matrix. Dedicated read-out electronics, software and mechanical supports have been developed. We report and discuss the challenges of the system in terms of the resulting quality of static images obtained with a 70 kV X-ray tube.

  2. Anatexis, hybridization and the modification of ancient crust: Mesozoic plutonism in the Old Woman Mountains area, California

    USGS Publications Warehouse

    Miller, C.F.; Wooden, J.L.

    1994-01-01

    A compositionally expanded array of granitic (s.l.) magmas intruded the > 2 Ga crust of the Old Woman Mountains area between 160 and 70 Ma. These magmas were emplaced near the eastern (inland) edge of the Jurassic/Cretaceous arcs of western North America, in an area where magma flux, especially during the Jurassic, was considerably lower than to the west. The Jurassic intrusives and over half of the Cretaceous intrusives are predominantly metaluminous and variable in composition; a major Cretaceous suite comprises only peraluminous monzogranite. Only the Jurassic intrusions show clear evidence for the presence of mafic liquids. All units, including the most mafic rocks, reveal isotopic evidence for a significant crustal component. However, none of the Mesozoic intrusives matches in isotopic composition either average pre-intrusion crust or any major unit of the exposed crust. Elemental inconsistencies also preclude closed system derivation from exposed crust. Emplacement of these magmas, which doubled the volume of the mid- to upper crust, did not dramatically change its elemental composition. It did, however, affect its Nd and especially Sr isotopic composition and modify some of the distinctive aspects of the elemental chemistry. We propose that Jurassic magmatism was open-system, with a major influx of mantle-derived mafic magma interacting strongly with the ancient crust. Mesozoic crustal thickening may have led to closed-system crustal melting by the Late Cretaceous, but the deep crust had been profoundly modified by earlier Mesozoic hybridization so that crustal melts did not simply reflect the original crustal composition. The clear evidence for a crustal component in magmas of the Old Woman Mountains area may not indicate any fundamental differences from the processes at work elsewhere in this or other magmatic arcs where the role of pre-existing crust is less certain. Rather, a compositionally distinctive, very old crust may simply have yielded a more

  3. Hybridization of Southern Hemisphere blue whale subspecies and a sympatric area off Antarctica: impacts of whaling or climate change?

    PubMed

    Attard, Catherine R M; Beheregaray, Luciano B; Jenner, K Curt S; Gill, Peter C; Jenner, Micheline-Nicole; Morrice, Margaret G; Robertson, Kelly M; Möller, Luciana M

    2012-12-01

    Understanding the degree of genetic exchange between subspecies and populations is vital for the appropriate management of endangered species. Blue whales (Balaenoptera musculus) have two recognized Southern Hemisphere subspecies that show differences in geographic distribution, morphology, vocalizations and genetics. During the austral summer feeding season, the Antarctic blue whale (B. m. intermedia) is found in polar waters and the pygmy blue whale (B. m. brevicauda) in temperate waters. Here, we genetically analyzed samples collected during the feeding season to report on several cases of hybridization between the two recognized blue whale Southern Hemisphere subspecies in a previously unconfirmed sympatric area off Antarctica. This means the pygmy blue whales using waters off Antarctica may migrate and then breed during the austral winter with the Antarctic subspecies. Alternatively, the subspecies may interbreed off Antarctica outside the expected austral winter breeding season. The genetically estimated recent migration rates from the pygmy to Antarctic subspecies were greater than estimates of evolutionary migration rates and previous estimates based on morphology of whaling catches. This discrepancy may be due to differences in the methods or an increase in the proportion of pygmy blue whales off Antarctica within the last four decades. Potential causes for the latter are whaling, anthropogenic climate change or a combination of these and may have led to hybridization between the subspecies. Our findings challenge the current knowledge about the breeding behaviour of the world's largest animal and provide key information that can be incorporated into management and conservation practices for this endangered species. PMID:23137299

  4. A National Assessment of Promising Areas for Switchgrass, Hybrid Poplar, or Willow Energy Crop Production

    SciTech Connect

    Graham, R.L.; Walsh, M.E.

    1999-02-01

    The objective of this paper is to systematically assess the cropland acreage that could support energy crops and the expected farm gate and delivered prices of energy crops. The assessment is based on output from two modeling approaches: (1) the Oak Ridge County-Level Energy Crop (ORECCL) database (1996 version) and (2) the Oak Ridge Integrated Bioenergy Analysis System (ORIBAS). The former provides county-level estimates of suitable acres, yields, and farmgate prices of energy crops (switchgrass, hybrid poplar, willow) for all fifty states. The latter estimates delivered feedstock prices and quantities within a state at a fine resolution (1 km2) and considers the interplay between transportation costs, farmgate prices, cropland density, and facility demand. It can be used to look at any type of feedstock given the appropriate input parameters. For the purposes of this assessment, ORIBAS has been used to estimate farmgate and delivered switchgrass prices in 11 states (AL, FL, GA, IA, M N, MO, ND, NE, SC, SD, and TN). Because the potential for energy crop production can be considered from several perspectives, and is evolving as policies, economics and our basic understanding of energy crop yields and production costs change, this assessment should be viewed as a snapshot in time.

  5. Fluorescence In Situ Hybridization (FISH) Assays for Diagnosing Malaria in Endemic Areas

    PubMed Central

    Shah, Jyotsna; Mark, Olivia; Weltman, Helena; Barcelo, Nicolas; Lo, Wai; Wronska, Danuta; Kakkilaya, Srinivas; Rao, Aravinda; Bhat, Shalia T.; Sinha, Ruchi; Omar, Sabah; Moro, Manuel; Gilman, Robert H.; Harris, Nick

    2015-01-01

    Malaria is a responsible for approximately 600 thousand deaths worldwide every year. Appropriate and timely treatment of malaria can prevent deaths but is dependent on accurate and rapid diagnosis of the infection. Currently, microscopic examination of the Giemsa stained blood smears is the method of choice for diagnosing malaria. Although it has limited sensitivity and specificity in field conditions, it still remains the gold standard for the diagnosis of malaria. Here, we report the development of a fluorescence in situ hybridization (FISH) based method for detecting malaria infection in blood smears and describe the use of an LED light source that makes the method suitable for use in resource-limited malaria endemic countries. The Plasmodium Genus (P-Genus) FISH assay has a Plasmodium genus specific probe that detects all five species of Plasmodium known to cause the disease in humans. The P. falciparum (PF) FISH assay and P. vivax (PV) FISH assay detect and differentiate between P. falciparum and P. vivax respectively from other Plasmodium species. The FISH assays are more sensitive than Giemsa. The sensitivities of P-Genus, PF and PV FISH assays were found to be 98.2%, 94.5% and 98.3%, respectively compared to 89.9%, 83.3% and 87.9% for the detection of Plasmodium, P. falciparum and P. vivax by Giemsa staining respectively. PMID:26333092

  6. Biostability of micro-photodiode arrays for subretinal implantation.

    PubMed

    Hämmerle, Hugo; Kobuch, Karin; Kohler, Konrad; Nisch, Wilfried; Sachs, Helmut; Stelzle, Martin

    2002-02-01

    Micro-photodiode arrays based on semiconductor chip technology are being developed to replace degenerated photoreceptor cells in the retina. Electric current is generated in tiny micro-photodiodes and delivered to the adjacent tissue by micro-electrodes. One of the main requirements of a sub-retinal implantable device is long-term stability versus corrosion in vivo (biostability). Biostability of micro-photodiode arrays (MPDA) was investigated in vitro and in vivo. No significant damage was found on chips immersed for up to 21 months in saline solution. Under in vivo conditions, however, the silicon oxide passivation layer of the chip was dissolved within a period of about 6-12 months. Subsequently, the underlying silicon was corroded. In contrast, stimulation electrodes consisting of titanium nitride were well preserved both in vitro and in vivo. The deterioration of the electrical properties of the micro-photodiodes correlated with the morphological damage observed. Strategies aiming at the development of an improved biostable encapsulation of neurotechnological implants have to be investigated and will be discussed briefly. PMID:11771699

  7. Increasing the dynamic range of CMOS photodiode imagers

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata (Inventor); Cunningham, Thomas J. (Inventor); Hancock, Bruce R. (Inventor)

    2007-01-01

    A multiple-step reset process and circuit for resetting a voltage stored on a photodiode of an imaging device. A first stage of the reset occurs while a source and a drain of a pixel source-follower transistor are held at ground potential and the photodiode and a gate of the pixel source-follower transistor are charged to an initial reset voltage having potential less that of a supply voltage. A second stage of the reset occurs after the initial reset voltage is stored on the photodiode and the gate of the pixel source-follower transistor and the source and drain voltages of the pixel source-follower transistor are released from ground potential thereby allowing the source and drain voltages of the pixel source-follower transistor to assume ordinary values above ground potential and resulting in a capacitive feed-through effect that increases the voltage on the photodiode to a value greater than the initial reset voltage.

  8. Area-efficient nonvolatile carry chain based on pass-transistor/atom-switch hybrid logic

    NASA Astrophysics Data System (ADS)

    Bai, Xu; Tsuji, Yukihide; Sakamoto, Toshitsugu; Morioka, Ayuka; Miyamura, Makoto; Tada, Munehiro; Banno, Naoki; Okamoto, Koichiro; Iguchi, Noriyuki; Hada, Hiromitsu

    2016-04-01

    For the first time, an area-efficient nonvolatile carry chain combining look-up tables and a pass-transistor-logic-based adder is newly developed using complementary atom switches without additional CMOS circuits. A proposed tristate switch composed of three pairs of complementary atom switches selects one of “0”, “1”, and the “carry_in” signal as the input of a common multiplexer for both a look-up table and an adder. The developed nonvolatile carry chain achieves the reductions of 20% area, 17% delay, and 17% power consumption, respectively, in comparison with a conventional nonvolatile carry chain using dedicated CMOS gates.

  9. Linear array of photodiodes to track a human speaker for video recording

    NASA Astrophysics Data System (ADS)

    DeTone, D.; Neal, H.; Lougheed, R.

    2012-12-01

    Communication and collaboration using stored digital media has garnered more interest by many areas of business, government and education in recent years. This is due primarily to improvements in the quality of cameras and speed of computers. An advantage of digital media is that it can serve as an effective alternative when physical interaction is not possible. Video recordings that allow for viewers to discern a presenter's facial features, lips and hand motions are more effective than videos that do not. To attain this, one must maintain a video capture in which the speaker occupies a significant portion of the captured pixels. However, camera operators are costly, and often do an imperfect job of tracking presenters in unrehearsed situations. This creates motivation for a robust, automated system that directs a video camera to follow a presenter as he or she walks anywhere in the front of a lecture hall or large conference room. Such a system is presented. The system consists of a commercial, off-the-shelf pan/tilt/zoom (PTZ) color video camera, a necklace of infrared LEDs and a linear photodiode array detector. Electronic output from the photodiode array is processed to generate the location of the LED necklace, which is worn by a human speaker. The computer controls the video camera movements to record video of the speaker. The speaker's vertical position and depth are assumed to remain relatively constant- the video camera is sent only panning (horizontal) movement commands. The LED necklace is flashed at 70Hz at a 50% duty cycle to provide noise-filtering capability. The benefit to using a photodiode array versus a standard video camera is its higher frame rate (4kHz vs. 60Hz). The higher frame rate allows for the filtering of infrared noise such as sunlight and indoor lighting-a capability absent from other tracking technologies. The system has been tested in a large lecture hall and is shown to be effective.

  10. Hybrid Ytterbium-doped large-mode-area photonic crystal fiber amplifier for long wavelengths.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Poli, Federica; Coscelli, Enrico; Jørgensen, Mette M; Laurila, Marko; Lægsgaard, Jesper; Broeng, Jes

    2012-03-12

    A large-mode-area Ytterbium-doped photonic crystal fiber amplifier with build-in gain shaping is presented. The fiber cladding consists of a hexagonal lattice of air holes, where three rows are replaced with circular high-index inclusions. Seven missing air holes define the large-mode-area core. Light confinement is achieved by combined index and bandgap guiding, which allows for single-mode operation and gain shaping through distributed spectral filtering of amplified spontaneous emission. The fiber properties are ideal for amplification in the long wavelength regime of the Ytterbium gain spectrum above 1100 nm, and red shifting of the maximum gain to 1130 nm is demonstrated. PMID:22418478

  11. A hybrid 802.16/802.11 network architecture for a United States coastal area network

    NASA Astrophysics Data System (ADS)

    Burbank, Jack L.; Kasch, William T.; Andrusenko, Julia; Haberman, Brian K.; Nichols, Robert; Zheng, Harold

    2007-04-01

    This paper presents a concept for a United States Coastal Area Network (U-SCAN) that is comprised of IEEE 802.11, 802.16, and satellite communications technologies. The Office of Naval Research (ONR) on behalf of the National Oceanographic Partnership Program (NOPP) has tasked The Johns Hopkins University Applied Physics Laboratory (JHU/APL) to perform an architectural study into the establishment of a United States Coastal Area Network (U-SCAN). The goal of this study is to define a wireless network architecture that can be deployed to enable contiguous coastal area network coverage for scientific, commercial, and homeland security (e.g. Coast Guard) applications within the United States Exclusive Economic Zone (EEZ), in a manner that is flexible, manageable, and affordable. The JHU/APL study will ultimately provide recommendations to NOPP regarding potential network architectures and technologies that could provide the desired capability, with a particular focus on commercial (both existing and emerging) technologies. This paper presents the envisioned U-SCAN architecture, and presents the envisioned technical capabilities and shortcomings of the component candidate technologies.

  12. Gene flow at major transitional areas in sea bass (Dicentrarchus labrax) and the possible emergence of a hybrid swarm.

    PubMed

    Quéré, Nolwenn; Desmarais, Erick; Tsigenopoulos, Costas S; Belkhir, Khalid; Bonhomme, François; Guinand, Bruno

    2012-12-01

    The population genetic structure of sea bass (Dicentrarchus labrax) along a transect from the Atlantic Ocean (AO) to the Eastern Mediterranean (EM) Sea differs from that of most other marine taxa in this area. Three populations (AO, Western Mediterranean [WM], EM) are recognized today, which were originally two allopatric populations. How two ancestral genetic units have evolved into three distinct units has not been addressed yet. Therefore, to investigate mechanisms that lead to the emergence of the central WM population, its current status, and its connectivity with the two parental populations, we applied 20 nuclear loci that were either gene associated or gene independent. Results confirmed the existence of three distinct gene pools, with higher differentiation at two transitional areas, the Almeria-Oran Front (AOF) and of the Siculo-Tunisian Strait (STS), than within any population. Significant linkage disequilibrium and heterozygote excess indicated that the STS is probably another tension zone, as already described for the AOF. Neutrality tests fail to reveal marker loci that could be driven by selection within or among metapopulations, except for locus DLA0068. Collectively, results support that the central WM population arose by trapping two tensions zones at distinct geographic locations of limited connectivity. Population assignment further revealed that WM individuals were more introgressed than individuals from the other two metapopulations. This suggests that this population might result from hybrid swarming, and was or is still seeded by genes received through the filter of each tension zone. PMID:23301173

  13. Micro-nano hybrid structures with manipulated wettability using a two-step silicon etching on a large area

    PubMed Central

    2011-01-01

    Nanoscale surface manipulation technique to control the surface roughness and the wettability is a challenging field for performance enhancement in boiling heat transfer. In this study, micro-nano hybrid structures (MNHS) with hierarchical geometries that lead to maximizing of surface area, roughness, and wettability are developed for the boiling applications. MNHS structures consist of micropillars or microcavities along with nanowires having the length to diameter ratio of about 100:1. MNHS is fabricated by a two-step silicon etching process, which are dry etching for micropattern and electroless silicon wet etching for nanowire synthesis. The fabrication process is readily capable of producing MNHS covering a wafer-scale area. By controlling the removal of polymeric passivation layers deposited during silicon dry etching (Bosch process), we can control the geometries for the hierarchical structure with or without the thin hydrophobic barriers that affect surface wettability. MNHS without sidewalls exhibit superhydrophilic behavior with a contact angle under 10°, whereas those with sidewalls preserved by the passivation layer display more hydrophobic characteristics with a contact angle near 60°. PMID:21711859

  14. CsI(Tl) with photodiodes for identifying subsurface radionuclide contamination

    SciTech Connect

    Stromswold, D.C.; Meisner, J.E.; Nicaise, W.F.

    1994-10-01

    At the US Department of Energy`s Hanford Site near Richland, Washington, underground radioactive contamination exists as the result of leaks, spills, and intentional disposal of waste products from plutonium-production operations. Characterizing these contaminants in preparation for environmental remediation is a major effort now in progress. In this paper, a cylindrical (15 {times} 61 mm) CsI(Tl) scintillation detector with two side-mounted photodiodes has been developed to collect spectral gamma-ray data in subsurface contaminated formations at the U.S. Department of Energy`s Hanford Site. It operates inside small-diameter, thick-wall steel pipes pushed into the ground to depths up to 20 m by a cone penetrometer. The detector provides a rugged, efficient, magnetic-field-insensitive means for identifying gamma-ray-emitting contaminants (mainly {sup 137}Cs and {sup 60}Co). Mounting two 3 x 30-mm photodiodes end-to-end on a flat area along the detector`s side provides efficient light collection over the length of the detector.

  15. Quantitative Analysis of Spectral Impacts on Silicon Photodiode Radiometers: Preprint

    SciTech Connect

    Myers, D. R.

    2011-04-01

    Inexpensive broadband pyranometers with silicon photodiode detectors have a non-uniform spectral response over the spectral range of 300-1100 nm. The response region includes only about 70% to 75% of the total energy in the terrestrial solar spectral distribution from 300 nm to 4000 nm. The solar spectrum constantly changes with solar position and atmospheric conditions. Relative spectral distributions of diffuse hemispherical irradiance sky radiation and total global hemispherical irradiance are drastically different. This analysis convolves a typical photodiode response with SMARTS 2.9.5 spectral model spectra for different sites and atmospheric conditions. Differences in solar component spectra lead to differences on the order of 2% in global hemispherical and 5% or more in diffuse hemispherical irradiances from silicon radiometers. The result is that errors of more than 7% can occur in the computation of direct normal irradiance from global hemispherical irradiance and diffuse hemispherical irradiance using these radiometers.

  16. Quantitative measurement of body motion using Schottky barrier silicon photodiode.

    PubMed

    Yoo, J H; Suh, I H; Wallace, S; Hankla, J W; Wauters, K A

    1979-11-01

    A new motion detection system has been developed using a laser beam and a Schottky barrier silicon photodiode. The system broadens the scope of gravitational center stabilography by facilitating the quantitative assessment of tremors of body appendages such as the hands and even the head. The system also eliminates cumbersome platforms and wire attachments previously used in gravitational center stabilography. The subject is asked to aim the beam at the photodiode. A quantitative off-center variation parameter, ARDS (Average Radial Distance Squared multiplied by time), was utilized in units of cm2 sec. A preliminary evaluation of the system shows that it is suitable for rapidly screening large numbers of subjects for localised neuromuscular control. PMID:526517

  17. Photon counting photodiode array detector for far ultraviolet (FUV) astronomy

    NASA Technical Reports Server (NTRS)

    Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

    1982-01-01

    A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location. Previously announced in STAR as N82-19118

  18. Experimental verification of the photodiode theory of SIS mixers

    NASA Technical Reports Server (NTRS)

    Woody, David P.; Wengler, Michael J.

    1993-01-01

    The authors describe the characterization and interpretation of the performance of SIS receivers within the framework of the photodiode theory of mixing. The quantum efficiency plays a dominant role in the theory, and a simple method of accurately measuring this parameter is presented. It is demonstrated that the quantum efficiency measurements can be conveniently made on a standard radio astronomy receiver and combined with the usual hot and cold load characterization to improve the understanding of the receiver's performance. The measurements verify that the photodiode theory of mixing accurately describes the receiver noise even at local-oscillator power levels well above the linear response range. The results for receivers operating at 100 and 240 GHz verify the utility of this approach. These methods should also prove useful in evaluating submillimeter receivers.

  19. Flexible germanium nanomembrane metal-semiconductor-metal photodiodes

    NASA Astrophysics Data System (ADS)

    Kim, Munho; Seo, Jung-Hun; Yu, Zongfu; Zhou, Weidong; Ma, Zhenqiang

    2016-08-01

    We demonstrate flexible Ge nanomembrane (Ge NM) based metal-semiconductor-metal photodiodes. The effect of uniaxial tensile strain on Ge NM based photodiodes was investigated using bending fixtures. Dark current density is decreased from 21.5 to 4.8 mA/cm2 at 3 V by a tensile strain of 0.42% while photon responsivity is increased from 0.2 to 0.45 A/W at the wavelength of 1.5 μm. Enhanced responsivity is also observed at longer wavelengths up to 1.64 μm. The uniaxial tensile strain effectively reduces the direct bandgap energy of the Ge NM, leading to a shift of the absorption edge toward a longer wavelength.

  20. New optical probe approach using mixing effect in planar photodiode for biomedical applications

    NASA Astrophysics Data System (ADS)

    Pereira, Tânia; Vaz, Pedro; Oliveira, Tatiana; Santos, Inês; Leal, Adriana; Almeida, Vânia; Pereira, Helena; Correia, Carlos; Cardoso, João.

    2013-05-01

    The laser diode self-mixing technique is a well-known and powerful interferometric technique that has been used in biomedical applications, namely for the extraction of cardiovascular parameters. However, to construct an optical probe using the self-mixing principle which is able to acquire signals in the human carotid artery, some problems are expected. The laser diode has a small aperture area, which means that, for physiological sensing purposes, it can be considered as a point-like detector. This feature imparts difficulties to quality recording of physiological signals since the number of photons collected and mixed in the cavity of the photodiode is very small. In order to overcome this problem, a new mixing geometry based on an external large area planar photodiode (PD) is used in the probe, enabling a much larger number of photons to be collected, hence improving the quality of the signal. In this work, the possibility to obtain the mixing effect outside the laser cavity using an external photodetector, such as a planar photodiode, is demonstrated. Two test benches were designed, both with of two reflectors. The first one, which reflects the light beam with the same frequency of the original one is fixed, and the second one, is movable, reflecting the Doppler shifted light to the photodetector. The first test bench has a fixed mirror in front of the movable mirror, creating an umbra and penumbra shadow above the movable mirror. To avoid this problem, another test bench was constructed using a wedged beam splitter (WSB) instead of a fixed mirror. This new assembly ensures the separation of a single input beam into multiple copies that undergo successive reflections and refractions. Some light waves are reflected by the planar surface of WSB, while other light beams are transmitted through the WSB, reaching the movable mirror. Also in this case, the movable mirror reflects the light with a Doppler frequency shift, and the PD receives both beams. The two test

  1. A wide area Bipolar Cascade Resonant Cavity Light Emitting Diode for a Hybrid Range-Intensity Sensor

    NASA Astrophysics Data System (ADS)

    Turner, Reginald J.

    Autonomous Ground Vehicles (AGV) will require high-speed, real-time three dimensional (3-D) image processing to navigate treacherous terrain in order to complete their assigned mission without a human in the loop. LIDAR scanners of the 3-D variety, provide the necessary area coverage for 3-D image processing, but lack the speed to deliver the collected data for real-time processing. A novel Hybrid Range-Intensity System (HRIS) has been proposed for imaging large swaths of area very rapidly. This system is comprised of two infrared cameras, an illumination source, a control and coordination system to position the cameras, and signal processing algorithms to extract the contour image of the scene. This dissertation focused on the development of an illuminator for the HRIS. This illuminator enables faster image rendering and reduces the potential of errors in return signal data, that could be generated from extremely rough terrain. Four major achievements resulted from this work, which advance the field of 3-D image acquisition. The first is that the TJ is an effective current spreading layer for LEDs with mesa width up to 140 mum and current densities of ˜ 1 x 106A/cm2. The TJ allows fabrication of an efficient illuminator, with required geometry for the HRIS to operate as a real-time 3-D imaging system. Secondly, a design for a Bipolar Cascade-Resonant Cavity Light Emitting Diode (BC-RCLED) has been accomplished, that will illuminate the FOV of the hybrid-ranged intensity system with a single sweep of the beam. This device is capable of producing ˜ 330 mW of output power. Additionally, from this work, key parameters for HRIS design were identified. Using a collection optic with a 15 cm diameter, an HRIS mounting height of 1.5 m, and a detector integration time of 330 msec, a SNR of 20 dB was achieved. Lastly, we demonstrated that the BC-RCLED designed for the HRIS can deliver sufficient energy to produce the required SNR. Also, through parametric analysis, we

  2. The hybrid photonic planar integrated receiver with a polymer optical waveguide

    NASA Astrophysics Data System (ADS)

    Busek, Karel; Jerábek, Vitezslav; Armas Arciniega, Julio; Prajzler, Václav

    2008-11-01

    This article describes design of the photonic receiver composed of the system polymer planar waveguides, InGaAs p-i-n photodiode and integrated HBT amplifier on a low loss composite substrate. The photonic receiver was the main part of the hybrid integrated microwave optoelectronic transceiver TRx (transciever TRx) for the optical networks PON (passive optical networks) with FTTH (fiber-to-the-home) topology. In this article are presented the research results of threedimensional field between output facet of a optical waveguide and p-i-n photodiode. In terms of our research, there was optimized the optical coupling among the facet waveguide and pi-n photodiode and the electrical coupling among p-i-n photodiode and input of HBT amplifier. The hybrid planar lightwave circuit (PLC) of the transceiver TRx will be composed from a two parts - polymer optical waveguide including VHGT filter section and a optoelectronic microwave section.

  3. Receiver characteristics of laser altimeters with avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Davidson, Frederic M.; Boutsikaris, Leo; Abshire, James B.

    1992-01-01

    The receiver characteristics of a laser altimeter system containing an avalanche photodiode photodetector are analyzed using the Gaussian approximation, the saddle-point approximation, and a nearly exact analysis. The last two methods are shown to yield very similar results except when the background noise is extremely low and the probability of false alarm is high. However, the Gaussian approximation method is shown to cause significant errors even under relatively high levels of background noise and received signal energy.

  4. Avalanche Photodiode Statistics in Triggered-avalanche Detection Mode

    NASA Technical Reports Server (NTRS)

    Tan, H. H.

    1984-01-01

    The output of a triggered avalanche mode avalanche photodiode is modeled as Poisson distributed primary avalanche events plus conditionally Poisson distributed trapped carrier induced secondary events. The moment generating function as well as the mean and variance of the diode output statistics are derived. The dispersion of the output statistics is shown to always exceed that of the Poisson distribution. Several examples are considered in detail.

  5. Spectral line-diode registry effects with photodiode array detectors

    SciTech Connect

    Winge, R.K.; Fassel, V.A.; Eckels, D.E.

    1986-05-01

    A limitation of photodiode array detectors for spectroscopic intensity measurements relates to the spacing of the diodes and the errors generated when a spectral line is not in exact registry with the diode or diodes from which its intensity is being measured. These misregistry intensity errors, which may be as high as 25 to 30%, are documented for a range of spectral bandwidths and for single diode (pixel) intensities and multiple diode summations of intensities.

  6. Potential for SPECT cameras utilizing photodiode readout of scintillator crystals

    SciTech Connect

    Moses, W.W.; Derenzo, S.E.; Gruber, G.J.; Huesman, R.H.

    1997-05-01

    We present a conceptual design for a SPECT detector consisting of an array of 3x3x5 mm CsI(Tl) scintillator crystals individually read out by an array of 3 mm square silicon photodiodes. The interaction position is not determined by Anger logic, but by the location of the individual crystal/photodiode element in which the gamma ray is observed. Since the design is modular (each module typically having 64 crystals, photodiodes, and charge amplifiers, and one multiplexer circuit to reduce the number of readout channels), a large variety of camera geometries can be realized. Advantages of this design over conventional cameras (NaI(Tl) scintillator/photomultiplier tube) are lower gain drift (i.e. higher stability), smaller size, significantly higher count rate capability, and potentially lower cost. For the 141 keV emissions of Tc-99m, both CsI(Tl) and NaI(Tl) have 85-90% photoelectric fraction, but CsI(TI) has an attenuation length of 3.0 mm as compared to 4.5 mm for NaI(Tl). Thus, a 5 mm thick CsI(Tl) camera has singular efficiency to a Nal(Tl) camera with a 7.5 mm thickness (between 1/4 and 3/8 inch). The light output of CsI(Tl) is 25% higher than that of Nal(Tl), and while its 565 nm emissions are not efficiently detected with photomultiplier tubes, they are well matched to photodiode detection.

  7. Geiger-mode avalanche photodiodes, history, properties and problems

    NASA Astrophysics Data System (ADS)

    Renker, D.

    2006-11-01

    Geiger-mode avalanche photodiodes (G-APDs) have been developed during recent years and promise to be an alternative to photomultiplier tubes. They have many advantages like single photon response, high detection efficiency, high gain at low bias voltage and very good timing properties but some of their properties, the dark count rate for example, can be a problem. Several types of G-APDs are on the market and should be selected carefully for a given application.

  8. Inexpensive photodiode arrays for use in rocket plume and hot source monitoring and diagnostics

    NASA Astrophysics Data System (ADS)

    Snider, Dallas; Shanks, Robert; Cole, Reagan; Hudson, M. Keith

    2003-09-01

    The spectroscopic analysis of plume emissions is a non-intrusive method which has been used to check for fatigue and possible damage throughout the pumps and other mechanisms in a rocket motor or engine. These components are made of various alloys. Knowing the composition of the alloys and for which parts they are used, one can potentially determine from the emissions in the plume which component is failing. Currently, optical multichannel analyser systems are being used which utilize charge coupled devices, cost tens of thousands of dollars, are somewhat delicate, and usually require cooling. We have developed two rugged instruments using less expensive linear photodiode arrays as detectors. A high-resolution system was used to detect atomic emission lines while a low-resolution system was used to detect molecular emission bands. We have also written data acquisition software and built electronic circuits to control the arrays and collect data. While the National Aeronautics and Space Administration has used similar systems for characterization of the space shuttle main engine, the emissions from other rocket systems have not been surveyed so well. The two instruments described will be utilized to study hybrid rocket emissions at the University of Arkansas-Little Rock hybrid rocket facility.

  9. Avalanche photodiode based detector for beam emission spectroscopy

    SciTech Connect

    Dunai, D.; Zoletnik, S.; Sarkoezi, J.; Field, A. R.

    2010-10-15

    An avalanche photodiode based (APD) detector for the visible wavelength range was developed for low light level, high frequency beam emission spectroscopy (BES) experiments in fusion plasmas. This solid state detector has higher quantum efficiency than photomultiplier tubes, and unlike normal photodiodes, it has internal gain. This paper describes the developed detector as well as the noise model of the electronic circuit. By understanding the noise sources and the amplification process, the optimal amplifier and APD reverse voltage setting can be determined, where the signal-to-noise ratio is the highest for a given photon flux. The calculations are compared to the absolute calibration results of the implemented circuit. It was found that for a certain photon flux range, relevant for BES measurements ({approx_equal}10{sup 8}-10{sup 10} photons/s), the new detector is superior to both photomultipliers and photodiodes, although it does not require cryogenic cooling of any component. The position of this photon flux window sensitively depends on the parameters of the actual experimental implementation (desired bandwidth, detector size, etc.) Several detector units based on these developments have been built and installed in various tokamaks. Some illustrative results are presented from the 8-channel trial BES system installed at Mega-Ampere Spherical Tokamak (MAST) and the 16-channel BES system installed at the Torus Experiment for Technology Oriented Research (TEXTOR).

  10. Photodiode-Like Behavior and Excellent Photoresponse of Vertical Si/Monolayer MoS2 Heterostructures

    PubMed Central

    Li, Yang; Xu, Cheng-Yan; Wang, Jia-Ying; Zhen, Liang

    2014-01-01

    Monolayer transition metal dichalcogenides (TMDs) and their van der Waals heterostructures have been experimentally and theoretically demonstrated as potential candidates for photovoltaic and optoelectronic devices due to the suitable bandgap and excellent light absorption. In this work, we report the observation of photodiode behavior in (both n- and p- type) silicon/monolayer MoS2 vertical heterostructures. The photocurrent and photoresponsivity of heterostructures photodiodes were dependent both on the incident light wavelength and power density, and the highest photoresponsivity of 7.2 A/W was achieved in n-Si/monolayer MoS2 vertical heterostructures photodiodes. Compared with n-Si/MoS2 heterostructures, the photoresponsivity of p-Si/MoS2 heterostructure was much lower. Kelvin probe microscope (KFM) results demonstrated the more efficient separation of photogenerated excitons in n-Si/MoS2 than that in p-Si/MoS2. Coupling KFM results with band alignments of (p-, n-) Si/MoS2 heterostructures, the origins of photodiode-like phenomena of p-Si/MoS2 and n-Si/MoS2 have been unveiled, that is intrinsic built-in electric field in p-n junction, and modulated barrier height and width at the interface in n-n junction. Our work may benefit to the deep understanding of the integration of two-dimensional materials with more conventional three-dimensional semiconductors, and then contribute to the developments in the area of van der Waals heterostructures. PMID:25424301

  11. Photodiode-like behavior and excellent photoresponse of vertical Si/monolayer MoS2 heterostructures.

    PubMed

    Li, Yang; Xu, Cheng-Yan; Wang, Jia-Ying; Zhen, Liang

    2014-01-01

    Monolayer transition metal dichalcogenides (TMDs) and their van der Waals heterostructures have been experimentally and theoretically demonstrated as potential candidates for photovoltaic and optoelectronic devices due to the suitable bandgap and excellent light absorption. In this work, we report the observation of photodiode behavior in (both n- and p- type) silicon/monolayer MoS2 vertical heterostructures. The photocurrent and photoresponsivity of heterostructures photodiodes were dependent both on the incident light wavelength and power density, and the highest photoresponsivity of 7.2 A/W was achieved in n-Si/monolayer MoS2 vertical heterostructures photodiodes. Compared with n-Si/MoS2 heterostructures, the photoresponsivity of p-Si/MoS2 heterostructure was much lower. Kelvin probe microscope (KFM) results demonstrated the more efficient separation of photogenerated excitons in n-Si/MoS2 than that in p-Si/MoS2. Coupling KFM results with band alignments of (p-, n-) Si/MoS2 heterostructures, the origins of photodiode-like phenomena of p-Si/MoS2 and n-Si/MoS2 have been unveiled, that is intrinsic built-in electric field in p-n junction, and modulated barrier height and width at the interface in n-n junction. Our work may benefit to the deep understanding of the integration of two-dimensional materials with more conventional three-dimensional semiconductors, and then contribute to the developments in the area of van der Waals heterostructures. PMID:25424301

  12. Highly enhanced avalanche probability using sinusoidally-gated silicon avalanche photodiode

    SciTech Connect

    Suzuki, Shingo; Namekata, Naoto Inoue, Shuichiro; Tsujino, Kenji

    2014-01-27

    We report on visible light single photon detection using a sinusoidally-gated silicon avalanche photodiode. Detection efficiency of 70.6% was achieved at a wavelength of 520 nm when an electrically cooled silicon avalanche photodiode with a quantum efficiency of 72.4% was used, which implies that a photo-excited single charge carrier in a silicon avalanche photodiode can trigger a detectable avalanche (charge) signal with a probability of 97.6%.

  13. High-Performance, Fullerene-Free Organic Photodiodes Based on a Solution-Processable Indigo.

    PubMed

    Kim, Il Ku; Li, Xin; Ullah, Mujeeb; Shaw, Paul E; Wawrzinek, Robert; Namdas, Ebinazar B; Lo, Shih-Chun

    2015-11-01

    A solution-processable dibromoindigo with an alkyoxyphenyl solubilizing group is developed and used as a new electron acceptor in organic photodiodes. The solution-processed fullerene-free organic photodiodes show an almost spectrally flat response with a high responsivity (0.4 A W(-1) ) and a high detectivity (1 × 10(12) Jones). These values are comparable to silicon-based photodiodes. PMID:26392063

  14. Absolute spectral response measurements of different photodiodes useful for applications in the UV spectral region

    NASA Astrophysics Data System (ADS)

    Pelizzo, Maria G.; Ceccherini, Paolo; Garoli, Denis; Masut, Pietro; Nicolosi, Piergiorgio

    2004-09-01

    Long UV radiation exposure can result in damages of biological tissues, as burns, skin aging, erythema and even melanoma cancer. In the past years an increase of melanoma cancer has been observed and associated to the atmospheric ozone deployment. Attendance of sun tanning unit centers has become a huge social phenomena, and the maximum UV radiation dose that a human being can receive is regulated by law. On the other side, UV radiation is largely used for therapeutic and germicidal purposes. In all these areas, spectroradiometer and radiomenter are needed for monitoring UVA (315-400 nm), UVB (280-315 nm) and UVC (100-280 nm) irradiance. We have selected some commercial photodiodes which can be used as solid state detectors in these instruments. We have characterized them by measuring their absolute spectral response in the 200 - 400 nm spectral range.

  15. Hard disk drive based microsecond X-ray chopper for characterization of ionization chambers and photodiodes.

    PubMed

    Müller, O; Lützenkirchen-Hecht, D; Frahm, R

    2015-03-01

    A fast X-ray chopper capable of producing ms long X-ray pulses with a typical rise time of few μs was realized. It is ideally suited to investigate the temporal response of X-ray detectors with response times of the order of μs to ms, in particular, any kind of ionization chambers and large area photo diodes. The drive mechanism consists of a brushless DC motor and driver electronics from a common hard disk drive, keeping the cost at an absolute minimum. Due to its simple construction and small dimensions, this chopper operates at home lab based X-ray tubes and synchrotron radiation sources as well. The dynamics of the most important detectors used in time resolved X-ray absorption spectroscopy, namely, ionization chambers and Passivated Implanted Planar Silicon photodiodes, were investigated in detail. The results emphasize the applicability of this X-ray chopper. PMID:25832273

  16. Hard disk drive based microsecond x-ray chopper for characterization of ionization chambers and photodiodes

    SciTech Connect

    Müller, O. Lützenkirchen-Hecht, D.; Frahm, R.

    2015-03-15

    A fast X-ray chopper capable of producing ms long X-ray pulses with a typical rise time of few μs was realized. It is ideally suited to investigate the temporal response of X-ray detectors with response times of the order of μs to ms, in particular, any kind of ionization chambers and large area photo diodes. The drive mechanism consists of a brushless DC motor and driver electronics from a common hard disk drive, keeping the cost at an absolute minimum. Due to its simple construction and small dimensions, this chopper operates at home lab based X-ray tubes and synchrotron radiation sources as well. The dynamics of the most important detectors used in time resolved X-ray absorption spectroscopy, namely, ionization chambers and Passivated Implanted Planar Silicon photodiodes, were investigated in detail. The results emphasize the applicability of this X-ray chopper.

  17. Compact multispectral photodiode arrays using micropatterned dichroic filters

    NASA Astrophysics Data System (ADS)

    Chandler, Eric V.; Fish, David E.

    2014-05-01

    The next generation of multispectral instruments requires significant improvements in both spectral band customization and portability to support the widespread deployment of application-specific optical sensors. The benefits of spectroscopy are well established for numerous applications including biomedical instrumentation, industrial sorting and sensing, chemical detection, and environmental monitoring. In this paper, spectroscopic (and by extension hyperspectral) and multispectral measurements are considered. The technology, tradeoffs, and application fits of each are evaluated. In the majority of applications, monitoring 4-8 targeted spectral bands of optimized wavelength and bandwidth provides the necessary spectral contrast and correlation. An innovative approach integrates precision spectral filters at the photodetector level to enable smaller sensors, simplify optical designs, and reduce device integration costs. This method supports user-defined spectral bands to create application-specific sensors in a small footprint with scalable cost efficiencies. A range of design configurations, filter options and combinations are presented together with typical applications ranging from basic multi-band detection to stringent multi-channel fluorescence measurement. An example implementation packages 8 narrowband silicon photodiodes into a 9x9mm ceramic LCC (leadless chip carrier) footprint. This package is designed for multispectral applications ranging from portable color monitors to purpose- built OEM industrial and scientific instruments. Use of an eight-channel multispectral photodiode array typically eliminates 10-20 components from a device bill-of-materials (BOM), streamlining the optical path and shrinking the footprint by 50% or more. A stepwise design approach for multispectral sensors is discussed - including spectral band definition, optical design tradeoffs and constraints, and device integration from prototype through scalable volume production

  18. Silicon avalanche photodiode operation and lifetime analysis for small satellites.

    PubMed

    Tan, Yue Chuan; Chandrasekara, Rakhitha; Cheng, Cliff; Ling, Alexander

    2013-07-15

    Silicon avalanche photodiodes (APDs) are sensitive to operating temperature fluctuations and are also susceptible to radiation flux expected in satellite-based quantum experiments. We introduce a low power voltage adjusting mechanism to overcome the effects of in-orbit temperature fluctuations. We also present data on the performance of Si APDs after irradiation (γ-ray and proton beam). Combined with an analysis of expected orbital irradiation, we propose that a Si APD in a 400 km equatorial orbit may operate beyond the lifetime of the satellite. PMID:23938543

  19. Reliability assessment of multiple quantum well avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Yun, Ilgu; Menkara, Hicham M.; Wang, Yang; Oguzman, Isamil H.; Kolnik, Jan; Brennan, Kevin F.; May, Gray S.; Wagner, Brent K.; Summers, Christopher J.

    1995-01-01

    The reliability of doped-barrier AlGaAs/GsAs multi-quantum well avalanche photodiodes fabricated by molecular beam epitaxy is investigated via accelerated life tests. Dark current and breakdown voltage were the parameters monitored. The activation energy of the degradation mechanism and median device lifetime were determined. Device failure probability as a function of time was computed using the lognormal model. Analysis using the electron beam induced current method revealed the degradation to be caused by ionic impurities or contamination in the passivation layer.

  20. MRS Photodiode, LED and extruded scintillator performance in magnetic field

    SciTech Connect

    Beznosko, D.; Blazey, G.; Dyshkant, A.; Francis, K.; Kubik, D.; Rykalin, V.; Zutshi, V.; /Northern Illinois U.

    2005-05-01

    The experimental results on the performance of the MRS (Metal/Resistor/Semiconductor) photodiode in the strong magnetic field of 4.4T, and the possible impact of the quench of the magnet at 4.5T on sensor's operation are reported. In addition, the experimental results on the performance of the extruded scintillator and WLS fiber, and various LEDs in the magnetic fields of 1.8T and 2.3T respectively, are detailed. The measurement method used is being described.

  1. Initial results from the Sherbrooke avalanche photodiode positron tomograph

    SciTech Connect

    Lecomte, R.; Cadorette, J.; Rodrigue, S.; Lapointe, D.; Rouleau, D.; Bentourkia, M.; Yao, R.; Msaki, P.

    1996-06-01

    The design features and engineering constraints of a PET system based on avalanche photodiode (APD) detectors have been described in a previous report. In this paper, the authors present the initial results obtained with the Sherbrooke APD-PET scanner, a very high spatial resolution device designed for dynamic imaging of small and medium-sized laboratory animals such as rats, cats, rabbits and small monkeys. Its physical performance has been evaluated in terms of resolution, sensitivity, count rate, random and scatter fractions, contrast and relative activity recovery as a function of object size. The capabilities of the scanner for biomedical research applications have been demonstrated using phantom and animal studies.

  2. Application of photodiodes to the detection of electromagnetic bursts

    NASA Technical Reports Server (NTRS)

    Fukushima, Y.; Saito, T.; Sakata, M.; Shima, M.; Yamamoto, Y.

    1985-01-01

    A new type of photodiode + scintillator (1 m2 x 1 cm) detector is developed to detect the large electro-magnetic burst under an EX-chamber. The threshold burst size is found to be 4.3 x 10 the 5 particles at the center of the scintillator. Therefore a gamma-ray family of 10 TeV is detectable by it, when it is set under 14 r.1. of iron. In addition, a very fast (2.4 nsec width) and very bright (correspond to 10 to the 6 particles) scintillation pulse has become avarable for this study.

  3. A 1.06 micrometer avalanche photodiode receiver

    NASA Technical Reports Server (NTRS)

    Eden, R. C.

    1975-01-01

    The development of a complete solid state 1.06 micron optical receiver which can be used in optical communications at data rates approaching 1.5 Gb/s, or in other applications requiring sensitive, short pulse detection, is reported. This work entailed both the development of a new type of heterojunction III-V semiconductor alloy avalanche photodiode and an extremely charge-sensitive wideband low noise preamp design making use of GaAs Schottky barrier-gate field effect transistors (GAASFET's) operating in in the negative-feedback transimpedance mode. The electrical characteristics of the device are described.

  4. Polarization sensitive silicon photodiodes using nanostructured metallic grids

    NASA Astrophysics Data System (ADS)

    Guillaumée, M.; Dunbar, L. A.; Santschi, Ch.; Grenet, E.; Eckert, R.; Martin, O. J. F.; Stanley, R. P.

    2009-05-01

    In this paper, we present the design, fabrication, and characterization of wire grid polarizers. These polarizers show high extinction ratios and high transmission with structure dimensions that are compatible with current complementary metal-oxide-semiconductor (CMOS) technology. To design these wire grids, we first analyze the transmission properties of single apertures. From the understanding of a single aperture, we apply a modal expansion method to model wire grids. The most promising grids are fabricated on both a glass substrate and CMOS photodiode. An extinction ratio higher than 200 is measured.

  5. 400-ps time resolution with a passively quenched avalanche photodiode.

    PubMed

    Grayson, T P; Wang, L J

    1993-06-01

    Avalanche photodiodes (APD's) operated in a single-photon-counting Geiger mode are becoming attractive alternatives to photomultiplier tubes for low-light-level detection and signal timing. By paying careful attention to the design and construction of a simple APD passive quenching circuit to reduce stray capacitances, we directly measured a time resolution of 410 ps FWHM for a commercial APD. A more detailed data analysis shows the actual time resolution to be ~ 390 ps FWHM. This is believed to be the most accurate time response for such a simple, inexpensive, and widely available device achieved to date. PMID:20829894

  6. Development of a testbed for flexible a-Si:H photodiode sensing arrays

    NASA Astrophysics Data System (ADS)

    Dominguez, Alfonso; Kunnen, George; Vetrano, Michael; Smith, Joseph; Marrs, Michael; Allee, David R.

    2013-05-01

    Large area, flexible sensing arrays for imaging, biochemical sensing and radiation detection are now possible with the development of flexible active matrix display technology. In particular, large-area flexible imaging arrays can provide considerable advancement in defense and security industries because of their inherent low manufacturing costs and physical plasticity that allows for increased adaptability to non-planar mounting surfaces. For example, a flexible array of photodetectors and lenslets formed into a cylinder could image simultaneously with a 360 degree view without the need for expensive bulky optics or a gimbaled mount. Here we report the design and development of a scalable 16x16 pixel testbed for flexible sensor arrays using commercial-off-the-shelf (COTS) parts and demonstrate the capture of a shadow image with an array of photodiodes and active pixel sensors on a plastic substrate. The image capture system makes use of an array of low-noise, InGaZnO active pixel amplifiers to detect changes in current in 2.4 μm-thick reverse-biased a-Si:H PIN diodes. A thorough characterization of the responsivity, detectivity, and optical gain of an a- Si:H photodiode is also provided. At the back end, analog capture circuitry progressively scans the array and constructs an image based on the electrical activity in each pixel. The use of correlated-double-sampling to remove fixed pattern noise is shown to significantly improve spatial resolution due to process variations. The testbed can be readily adapted for the development of neutron, alpha-particle, or X-ray detection arrays given an appropriate conversion layer.

  7. Effect of Fabric Cover and Pore Area Distribution of Carbon/Stainless Steel/Polypropylene Hybrid Yarn-Woven Fabric on Electromagnetic Shielding Effectiveness

    NASA Astrophysics Data System (ADS)

    Krishnasamy, Jagatheesan; Ramasamy, Alagirusamy; Das, Apurba; Basu, Ananjan

    2016-06-01

    The electromagnetic shielding behavior of fabrics woven with carbon/stainless steel/polypropylene (C/SS/PP) hybrid yarns were investigated in the frequency range of 300 kHz to 1.5 GHz. This study mainly emphasizes the electromagnetic shielding behavior of C/SS/PP hybrid yarn fabric and the effect of different fabric parameters such as pick density, fabric architecture and number of fabric layers on shielding effectiveness (SE) of fabrics with C/SS/PP hybrid yarns. The SE of fabric samples were tested by a vector network analyzer using a coaxial transmission line tester. In addition, surface images of different fabric structures were examined to appreciate the effect of yarn floats on the shielding behavior of fabrics. From the SE test, it was observed that an increase in pick density increases the SE of C/SS/PP hybrid yarn fabric due to addition of carbon and SS content in the fabric. Besides, the fabric cover and pore area distribution are also changed for varying pick densities. Essentially, a fabric's architecture plays an important role in the fabric cover and pore area distribution. The one-end float (1/1 plain) fabric of 6.3 ppcm provides higher shielding of 88.44 dB than a 4-end (4/1 twill) or 7-end float (8-end satin) fabrics of 6.3 ppcm. Moreover, an increase in the number of fabric layers also improves the SE of fabrics. The developed C/SS/PP hybrid yarn fabric can be used for shielding wireless transmissions, radar transmissions and for shielding panels.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  9. Low noise, IR-blind organohalide perovskite photodiodes for visible light detection and imaging.

    PubMed

    Lin, Qianqian; Armin, Ardalan; Lyons, Dani M; Burn, Paul L; Meredith, Paul

    2015-03-25

    Solution-processed organohalide perov-skite photodiodes that have performance metrics matching silicon, but are infrared-blind are reported. The perovskite photodiodes operate in the visible band, have low dark current and noise, high specific detectivity, large linear dynamic range, and fast temporal response. Their properties make them promising candidates for imaging applications. PMID:25677496

  10. 4H-SiC photodiode model for DC SPICE circuit simulation

    NASA Astrophysics Data System (ADS)

    Kociubiński, Andrzej; Duk, Mariusz; Korona, Mateusz; Muzyka, Krzysztof

    2015-09-01

    Technology, characterization and in particularly modeling of 4H-SiC photodiode have been presented in this paper. Modeling and simulation has been performed using PSPICE environment. Comparison of simulation with real results for electrical characteristic (I-V) of circular SiC photodiodes has been also presented.

  11. Free-electron THz-reabsorption in distributed photodiode structures

    NASA Astrophysics Data System (ADS)

    Calle, V. H.; Michael, E. A.

    2015-10-01

    Ultra-fast photodiodes based on vertical p-i-n or uni-traveling (UTC) mesa structures require a highly doped base layer that makes a well-conducting transverse connection between the mesa bottom layer and the bottom metal contacts. To reach the lowest possible THz loss, the question arises on what doping levels would be optimal for this layer. Doping levels of up to ≈ 5× {{10}19} cm-3 can be reached in InP, corresponding to conductivities of around 8× {{10}5} S m-1, which is still much lower than those of metal conductors. A full-wave analysis, which is executed in HFSS™ and CST Microwave Studio™ and reported here, shows that a valley of low loss exists around a conductivity of 5× {{10}4} S m-1 (estimated doping value ≈ 2× {{10}18} cm-3), in the middle of a conductivity range of excessive terahertz absorption, making this value the best choice for the whole frequency range up to 2000 GHz. The results are supported by an analytical solution in a simplified transmission line model. The results are expected to be significant for designing future distributed photonic devices such as traveling-wave (TW) photodiodes.

  12. Gamma ray spectroscopy and timing using LSO and PIN photodiodes

    SciTech Connect

    Moses, W.W.; Derenzo, S.E.; Melcher, C.L.; Manente, R.A.

    1994-11-01

    The high density, high light output, and short decay time of LSO (lutetium orthosilicate, Lu{sub 2}SiO{sub 5}:Ce) make it an attractive scintillator for gamma ray spectroscopy. The low cost, small size, high quantum efficiency, and ruggedness of silicon photodiodes make them attractive photodetectors for this same application, although their high noise (Compared to a photomultiplier tube) reduces their appeal. In this work the authors measure the gamma ray energy resolution, timing accuracy, and conversion factor from gamma energy to number of electron-hole pairs produced with a 3 x 3 x 22 mm{sup 3} LSO scintillator crystal read out with a 3 x 3 mm{sup 2} silicon PIN photodiode. When the detector is excited with 511 keV photons, a photopeak centered at 1,940 e{sup {minus}} with 149 keV fwhm is observed and a timing signal with 35 ns fwhm jitter is produced. When the detector is excited with 1,275 keV photons, a photopeak centered at 4,910 e{sup {minus}} with 149 keV fwhm is observed and a timing signal with 25 ns fwhm jitter is produced. While these performance measures are inferior to those obtained with photomultiplier tubes, they are acceptable for some applications.

  13. Complementary Metal Oxide Semiconductor-Compatible Back-Side-Illuminated Photodiode for Optoelectronic Integrated Circuit Devices

    NASA Astrophysics Data System (ADS)

    Shin, Sang-Baie; Sekiguchi, Hiroto; Okada, Hiroshi; Wakahara, Akihiro

    2013-04-01

    In this study, the prototype optoelectronic integrated circuits (OEICs) operating with optical input signals were designed and fabricated. A back-side-illuminated (BSI) photodiode was designed and demonstrated by a newly proposed practical method, utilizing micro-electromechanical systems (MEMS) and postcomplement metal oxide semiconductor (CMOS) processes. Additional fabrication processes for the BSI photodiode were proposed and described in detail in this paper. The operational amplifier for amplification of the optical current by the BSI photodiode as the transimpedance amplifier was designed and fabricated. And the pulse width modulation (PWM) wave generator was implemented for modulating optical signals as the prototype OEIC device. The maximum quantum efficiency of 28.4% was obtained from the fabricated BSI photodiode. Output signals of PWM were successfully controlled by the generated optical current of the BSI photodiode.

  14. Impact ionization engineered avalanche photodiode arrays for free space optical communication

    NASA Astrophysics Data System (ADS)

    Ferraro, Mike S.; Rabinovich, William S.; Clark, William R.; Waters, William D.; Campbell, Joe C.; Mahon, Rita; Vaccaro, Kenneth; Krejca, Brian D.

    2016-03-01

    High sensitivity photodetectors serve two purposes in free space optical communication: data reception and position sensing for pointing, tracking, and stabilization. Because of conflicting performance criteria, two separate detectors are traditionally utilized to perform these tasks but recent advances in the fabrication and development of large area, low noise avalanche photodiode (APD) arrays have enabled these devices to be used both as position sensitive detectors (PSD) and as communications receivers. Combining these functionalities allows for more flexibility and simplicity in optical assembly design without sacrificing the sensitivity and bandwidth performance of smaller, single element data receivers. Beyond eliminating the need to separate the return beam into two separate paths, these devices enable implementation of adaptive approaches to compensate for focal plane beam wander and breakup often seen in highly scintillated terrestrial and maritime optical links. While the Naval Research Laboratory (NRL) and Optogration Inc, have recently demonstrated the performance of single period, InAlAs/InGaAs APD arrays as combined data reception and tracking sensors, an impact ionization engineered (I2E) epilayer design achieves even lower carrier ionization ratios by incorporating multiple multiplication periods engineered to suppress lower ionization rate carriers while enhancing the higher ionization rate carriers of interest. This work presents a three period I2E concentric, five element avalanche photodiode array rated for bandwidths beyond 1GHz with measured carrier ionization ratios of 0.05-0.1 at moderate APD gains. The epilayer design of the device will be discussed along with initial device characterization and high speed performance measurements.

  15. Design of a back-illuminated, crystallographically etched, silicon-on-sapphire avalanche photodiode with monolithically integrated microlens, for dual-mode passive & active imaging arrays

    NASA Astrophysics Data System (ADS)

    Stern, Alvin G.; Cole, Daniel C.

    2008-12-01

    There is a growing need in space and environmental research applications for dual-mode, passive and active 2D and 3D ladar imaging methods. To fill this need, an advanced back-illuminated avalanche photodiode (APD) design is presented based on crystallographically etched (100) epitaxial silicon on R-plane sapphire (SOS), enabling single photon sensitive, solid-state focal plane arrays (FPAs) with wide dynamic range, supporting passive and active imaging capability in a single FPA. When (100) silicon is properly etched with KOH:IPA:H2O solution through a thermally grown oxide mask, square based pyramidal frustum or mesa arrays result with the four mesa sidewalls of the APD formed by (111) silicon planes that intersect the (100) planes at a crystallographic angle, Φc = 54.7°. The APD device is fabricated in the mesa using conventional silicon processing technology. Detectors are back-illuminated through light focusing microlenses fabricated in the thinned, AR-coated sapphire substrate. The APDs share a common, front-side anode contact, made locally at the base of each device mesa. A low resistance (Al) or (Cu) metal anode grid fills the space between pixels and also inhibits optical cross-talk. SOS-APD arrays are indium bump-bonded to CMOS readout ICs to produce hybrid FPAs. The quantum efficiency for the square 27 µm pixels exceeds 50% for 250 nm < λ < 400 nm and exceeds 80% for 400 nm < λ < 700 nm. The sapphire microlenses compensate detector quantum efficiency loss resulting from the mesa geometry and yield 100% sensitive-area-fill-factor arrays, limited in size only by the wafer diameter.

  16. A hybrid WDM/OCDMA ring with a dynamic add/drop function based on Fourier code for local area networks.

    PubMed

    Choi, Yong-Kyu; Hosoya, Kenta; Lee, Chung Ghiu; Hanawa, Masanori; Park, Chang-Soo

    2011-03-28

    We propose and experimentally demonstrate a hybrid WDM/OCDMA ring with a dynamic add/drop function based on Fourier code for local area networks. Dynamic function is implemented by mechanically tuning the Fourier encoder/decoder for optical code division multiple access (OCDMA) encoding/decoding. Wavelength division multiplexing (WDM) is utilized for node assignment and 4-chip Fourier code recovers the matched signal from the codes. For an optical source well adapted to WDM channels and its short optical pulse generation, reflective semiconductor optical amplifiers (RSOAs) are used with a fiber Bragg grating (FBG) and gain-switched. To demonstrate we experimentally investigated a two-node hybrid WDM/OCDMA ring with a 4-chip Fourier encoder/decoder fabricated by cascading four FBGs with the bit error rate (BER) of <10(-9) for the node span of 10.64 km at 1.25 Gb/s. PMID:21451649

  17. Si/Ge photodiodes for coherent and analog communication

    NASA Astrophysics Data System (ADS)

    Piels, Molly

    High-speed photodiodes have diverse applications in wireless and fiber communications. They can be used as output stages for antenna systems as well as receivers for fiber optic networks. Silicon is an attractive substrate material for photonic components for a number of reasons. Low cost manufacturing in CMOS fabrication facilities, low material loss at telecommunications wavelengths, and relatively simple co-packaging with electronics are all driving interest in silicon photonic devices. Since silicon does not absorb light at telecommunications wavelengths, photodetector fabrication requires the integration of either III-V materials or germanium. Recent work on germanium photodetectors has focused on low-capacitance devices suitable for integration with silicon electronics. These devices have excellent bandwidth and efficiency, but have not been designed for the levels of photocurrent required by coherent and analog systems. This thesis explores the design, fabrication, and measurement of photodetectors fabricated on silicon with germanium absorbing regions for high speed and high power performance. There are numerous design trade-offs between speed, efficiency, and output power. Designing for high bandwidth favors small devices for low capacitance. Small devices require abrupt absorption profiles for good efficiency, but design for high output power favors large devices with dilute absorption. The absorption profile can be controlled by the absorber layer thickness, but this will also affect the bandwidth and power handling. This work quantifies the trade-offs between high speed, high efficiency, and high power design. Intrinsic region thickness and absorption profile are identified as the most important design variables. For PIN structures, the absorption profile and intrinsic region thickness are both functions of the Ge thickness, but in uni-traveling carrier (UTC) structures the absorption profile and intrinsic region can be designed independently. This

  18. Responsivity of Diamond X-ray Photodiodes Calibrated at NSLS

    SciTech Connect

    Keister,J.W.; Smedley, J.; Muller, E. M.; Bohon, J.

    2009-09-27

    Single crystal, high purity synthetic diamond is used as photoabsorption and carrier transport medium in x-ray photodiodes. While the thermal / mechanical robustness and high x-ray transmission of diamond make such devices attractive for synchrotron instrumentation, state-of-the-art quality material and electrical interfaces further make such detectors feasible. The present work develops methodology for attaining calculable responsivity (photocurrent yield) over a wide range of photon energies (0.2 to 28 keV) to within 5% accuracy. These methods achieve linear response for up to 0.2 W absorbed x-ray power and response time as low as 1 ns. Details of contact formation / robustness and bias configuration are explored.

  19. Temperature Control of Avalanche Photodiode Using Thermoelectric Cooler

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Luck, William S., Jr.; DeYoung, Russell J.

    1999-01-01

    Avalanche photodiodes (APDS) are quantum optical detectors that are used for visible and near infrared optical detection applications. Although APDs are compact, rugged, and have an internal gain mechanism that is suitable for low light intensity; their responsivity, and therefore their output, is strongly dependent on the device temperature. Thermoelectric coolers (TEC) offers a suitable solution to this problem. A TEC is a solid state cooling device, which can be controlled by changing its current. TECs are compact and rugged, and they can precisely control the temperature to within 0.1 C with more than a 150 C temperature gradient between its surfaces. In this Memorandum, a proportional integral (PI) temperature controller for APDs using a TEC is discussed. The controller is compact and can successfully cool the APD to almost 0 C in an ambient temperature environment of up to 27 C.

  20. Colored adaptive compressed imaging with a single photodiode.

    PubMed

    Yan, Yiyun; Dai, Huidong; Liu, Xingjiong; He, Weiji; Chen, Qian; Gu, Guohua

    2016-05-10

    Computational ghost imaging is commonly used to reconstruct grayscale images. Currently, however, there is little research aimed at reconstructing color images. In this paper, we theoretically and experimentally demonstrate a colored adaptive compressed imaging method. Benefiting from imaging in YUV color space, the proposed method adequately exploits the sparsity of the U, V components in the wavelet domain, the interdependence between luminance and chrominance, and human visual characteristics. The simulation and experimental results show that our method greatly reduces the measurements required and offers better image quality compared to recovering the red (R), green (G), and blue (B) components separately in RGB color space. As the application of a single photodiode increases, our method shows great potential in many fields. PMID:27168280

  1. Studies of avalanche photodiodes for scintillating fibre tracking readout

    SciTech Connect

    Fenker, H; Thomas, J

    1993-01-01

    Avalanche Photodiodes (APDs) operating in ``Geiger Mode`` have been studied in a fibre tracking readout environment. A fast recharge circuit has been developed for high rate data taking, and results obtained from a model fibre tracker in the test beam at Brookhaven National Laboratory are presented. A high rate calibrated light source has been developed using a commercially available laser diode and has been used to measure the efficiency of the devices. The transmission of the light from a 1mm fibre onto a 0.5mm diameter APD surface has been identified as the main problem in the use of these particular devices for scintillating fibre tracking in the Superconducting Supercollider environment. Solutions to this problem are proposed.

  2. Perpendicular hot electron transport in the spin-valve photodiode

    NASA Astrophysics Data System (ADS)

    Huang, Biqin; Appelbaum, Ian

    2006-08-01

    The spin-valve photodiode is a ferromagnetic metal multilayer/n-type semiconductor Schottky device operated by photoexciting hot electrons in the metal and causing internal photoemission (IPE) into the semiconductor. Simple IPE theory predicts that the magnitude of the spin-valve effect (modulation of the photocurrent) should monotonically increase as a metallic capping layer thickness increases. Experimentally, however, we observe a nonmonotonic behavior with cap layer thickness, where the magnetocurrent reaches an optimum value and then decreases. The disagreement between this experimental result and the previous theoretical model is discussed, leading to an alternative interpretation of transport including reflection from the air-metal interface. Calculations with this model are consistent with the observed phenomena.

  3. Avalanche photodiode based time-of-flight mass spectrometry

    SciTech Connect

    Ogasawara, Keiichi Livi, Stefano A.; Desai, Mihir I.; Ebert, Robert W.; McComas, David J.; Walther, Brandon C.

    2015-08-15

    This study reports on the performance of Avalanche Photodiodes (APDs) as a timing detector for ion Time-of-Flight (TOF) mass spectroscopy. We found that the fast signal carrier speed in a reach-through type APD enables an extremely short timescale response with a mass or energy independent <2 ns rise time for <200 keV ions (1−40 AMU) under proper bias voltage operations. When combined with a microchannel plate to detect start electron signals from an ultra-thin carbon foil, the APD comprises a novel TOF system that successfully operates with a <0.8 ns intrinsic timing resolution even using commercial off-the-shelf constant-fraction discriminators. By replacing conventional total-energy detectors in the TOF-Energy system, APDs offer significant power and mass savings or an anti-coincidence background rejection capability in future space instrumentation.

  4. Correcting for accidental correlations in saturated avalanche photodiodes.

    PubMed

    Grieve, J A; Chandrasekara, R; Tang, Z; Cheng, C; Ling, A

    2016-02-22

    In this paper we present a general method for estimating rates of accidental coincidence between a pair of single photon detectors operated within their saturation regimes. By folding the effects of recovery time of both detectors and the detection circuit into an "effective duty cycle" we are able to accomodate complex recovery behaviour at high event rates. As an example, we provide a detailed high-level model for the behaviour of passively quenched avalanche photodiodes, and demonstrate effective background subtraction at rates commonly associated with detector saturation. We show that by post-processing using the updated model, we observe an improvement in polarization correlation visibility from 88.7% to 96.9% in our experimental dataset. This technique will be useful in improving the signal-to-noise ratio in applications which depend on coincidence measurements, especially in situations where rapid changes in flux may cause detector saturation. PMID:26907016

  5. Detector telescope array: silicon--CsI(Tl)--photodiode

    NASA Astrophysics Data System (ADS)

    Norbeck, E.; Yang, L. B.; Pogodin, P.; Ingram, F. D.

    1999-10-01

    A closely packed array of 60 telescopes was developed for use at forward angles in the 4π Array at the National Superconducting Cyclotron Laboratory at Michigan State University. The telescopes resolve isotopes and cover nearly 100% of the solid angle assigned to the array. These requirements and limitations of space and funding resulted in a number of novel features, some of which will be useful in other applications. These features include: photodiodes of arbitrary shape with no frame around the edge, replacement of aluminized Mylar with aluminum leaf, an inexpensive silicon diode leakage current monitor that presents a graph of leakage current vs detector number, and a low noise but inexpensive preamplifier chip. Experience with the array showed that compounds in the outer insulation layer of some types of coax cable can seriously contaminate a vacuum system. The use of computer aided design and computer controlled machine tools reduced the cost of the structural parts by orders of magnitude.

  6. Innovative Detection System of Ochratoxin A by Thin Film Photodiodes

    PubMed Central

    Caputo, Domenico; de Cesare, Giampiero; Fanelli, Corrado; Nascetti, Augusto; Ricelli, Alessandra; Scipinotti, Riccardo

    2007-01-01

    In this work we present, for the first time, a rapid, compact and innovative method for detection of Ochratoxin A (OTA) based on hydrogenated amorphous silicon (a-Si:H) sensors. 2 μl of acidified toluene containing OTA at different concentrations were spotted on the silica side of a High Performance Thin Layer Cromatography plate and aligned with a a-Si:H p-i-n photodiode deposited by Plasma Enhanced Chemical Vapor Deposition on a different glass substrate. As an UV radiation excites the mycotoxin, the re-emitted light is detected by the a-Si:H sensor. Results show a very good linearity between OTA concentration and the sensor photocurrent over almost three orders of magnitude. The minimum detected OTA concentration is equal to 0.1ng, showing that the presented system has the potential for a low cost system suitable for the early detection of toxins in foods.

  7. CLASSICAL AREAS OF PHENOMENOLOGY: Below-diffract ion-limited hybrid recording using silicon thin film super-resolution structure

    NASA Astrophysics Data System (ADS)

    Jiao, Xin-Bing; Wei, Jing-Song; Gan, Fu-Xi

    2009-12-01

    We report on new experimental results for below-diffraction-limited hybrid recording. In our experiments, by means of focused laser assisted magnetic recording, the magnetic domains within TbFeCo thin films are obtained under an external perpendicular direct magnetic field. For a single magnetic medium, the domain size is mainly determined by the focused spot, which is about 620 nm for the laser wavelength λ = 406 nm, and a numerical aperture of the lens of 0.80. However, when a silicon thin film structure is inserted between the substrate and the magnetic medium, the recording domains can be reduced obviously. By optimizing the experimental condition, even the size can be reduced to about 100 nm, which is below the diffraction limit, i.e. about 1/6 of the spot size. This is very useful for improving the hybrid recording density in practical applications.

  8. Performance limitations of InGaAs photodiodes

    NASA Astrophysics Data System (ADS)

    Rogalski, Antoni

    1999-04-01

    The carrier lifetimes in InxGa1-xAs (InGaAs) ternary alloys for radiative and Auger recombination are calculated for temperature 300 K in the short wavelength range 1.5 < (lambda) < 3.7 micrometers . Due to photon recycling, an order of magnitude enhancements in the radiative lifetimes over those obtained from the standard van Roosbroeck and Shockley expression, has been assumed. The possible Auger recombination mechanisms (CHCC, CHLH and CHSH processes) in direct-gap semiconductors are investigated. In n-type and p-type materials the carrier lifetimes are similar. It is clearly shown that in the range of low doping concentration, the carrier lifetime is determined by radiative recombination. For n-type material in the range of higher doping level, a competition between radiative and CHCC processes take place; instead for p-type materials the most effective channel of Auger mechanisms is the CHSH process. A special attention has been put on discussion of the carrier lifetimes in both types of In0.53Ga0.47As materials. Consequence of enhancement in the radiative lifetime leads to higher ultimate performance of photodiodes. The performance (RoA product) of heterostructure InGaAs photovoltaic devices are analyzed. Both the n-on-p (with p-type active region) as well as p-on- n (with n-type active region) are considered. Finally, theoretically predicted performance of InGaAs photodiodes are compared with experimental data reported by other authors.

  9. The quantum efficiency of HgCdTe photodiodes in relation to the direction of illumination and to their geometry

    NASA Technical Reports Server (NTRS)

    Rosenfeld, D.; Bahir, G.

    1993-01-01

    A theoretical study of the effect of the direction of the incident light on the quantum efficiency of homogeneous HgCdTe photodiodes suitable for sensing infrared radiation in the 8-12 microns atmospheric window is presented. The probability of an excess minority carrier to reach the junction is derived as a function of its distance from the edge of the depletion region. Accordingly, the quantum efficiency of photodiodes is presented for two geometries. In the first, the light is introduced directly to the area in which it is absorbed (opaque region), while in the second, the light passes through a transparent region before it reaches the opaque region. Finally, the performance of the two types of diodes is analyzed with the objective of finding the optimal width of the absorption area. The quantum efficiency depends strongly on the way in which the light is introduced. The structure in which the radiation is absorbed following its crossing the transparent region is associated with both higher quantum efficiency and homogeneity. In addition, for absorption region widths higher than a certain minimum, the quantum efficiency in this case is insensitive to the width of the absorption region.

  10. Remobilization of granitoid rocks through mafic recharge: evidence from basalt-trachyte mingling and hybridization in the Manori-Gorai area, Mumbai, Deccan Traps

    NASA Astrophysics Data System (ADS)

    Zellmer, Georg F.; Sheth, Hetu C.; Iizuka, Yoshiyuki; Lai, Yi-Jen

    2012-01-01

    Products of contrasting mingled magmas are widespread in volcanoes and intrusions. Subvolcanic trachyte intrusions hosting mafic enclaves crop out in the Manori-Gorai area of Mumbai in the Deccan Traps. The petrogenetic processes that produced these rocks are investigated here with field data, petrography, mineral chemistry, and whole rock major, trace, and Pb isotope chemistry. Local hybridization has occurred and has produced intermediate rocks such as a trachyandesitic dyke. Feldspar crystals have complex textures and an unusually wide range in chemical composition. Crystals from the trachytes cover the alkali feldspar compositional range and include plagioclase crystals with anorthite contents up to An47. Crystals from the mafic enclaves are dominated by plagioclase An72-90, but contain inclusions of orthoclase and other feldspars covering the entire compositional range sampled in the trachytes. Feldspars from the hybridized trachyandesitic dyke yield mineral compositions of An80-86, An47-54, Ab94-99, Or45-60, and Or96-98, all sampled within individual phenocrysts. We show that these compositional features are consistent with partial melting of granitoid rocks by influx of mafic magmas, followed by magma mixing and hybridization of the partial melts with the mafic melts, which broadly explains the observed bulk rock major and trace element variations. However, heterogeneities in Pb isotopic compositions of trachytes are observed on the scale of individual outcrops, likely reflecting initial variations in the isotopic compositions of the involved source rocks. The combined data point to one or more shallow-level trachytic magma chambers disturbed by multiple injections of trachytic, porphyritic alkali basaltic, and variably hybridized magmas.

  11. High performance x-ray imaging detectors on foil using solution-processed organic photodiodes with extremely low dark leakage current (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Kumar, Abhishek; Moet, Date; van der Steen, Jan Laurens; van Breemen, Albert; Shanmugam, Santhosh; Gilot, Jan; Andriessen, Ronn; Simon, Matthias; Ruetten, Walter; Douglas, Alexander; Raaijmakers, Rob; Malinowski, Pawel E.; Myny, Kris; Gelinck, Gerwin

    2015-10-01

    High performance X-ray imaging detectors on foil using solution-processed organic photodiodes with extremely low dark leakage current Abhishek Kumara, Date Moeta, Albert van Breemena, Santhosh Shanmugama, Jan-Laurens van der Steena, Jan Gilota, Ronn Andriessena, Matthias Simonb, Walter Ruettenb, Alexander U. Douglasb, Rob Raaijmakersc, Pawel E. Malinowskid, Kris Mynyd and Gerwin H. Gelincka,e a. Holst Centre/TNO, High Tech Campus 31, Eindhoven 5656 AE, The Netherlands b. Philips Research, High Tech Campus 34, 5656 AE Eindhoven, The Netherlands c. Philips Healthcare, Veenpluis 6-8, 5684 PC Best, The Netherlands d. Department of Large Area Electronics, imec vzw, Kapeldreef 75, Leuven B3001, Belgium e. Applied Physics Department, TU Eindhoven, Eindhoven, The Netherlands We demonstrate high performance X-ray imaging detectors on foil suitable for medical grade X-ray imaging applications. The detectors are based on solution-processed organic photodiodes forming bulk-heterojunctions from photovoltaic donor and acceptor blend. The organic photodiodes are deposited using an industrially compatible slot die coating technique with end of line processing temperature below 100°C. These photodiodes have extremely low dark leakage current density of 10-7 mA/cm2 at -2V bias with very high yield and have peak absorption around 550 nm wavelength. We combine these organic photodiodes with high mobility metal oxide semiconductor based thin film transistor arrays with high pixel resolution of 200ppi on thin plastic substrate. When combined with a typical CsI(TI) scintillator material on top, they are well suited for low dose X-ray imaging applications. The optical crosstalk is insignificant upto resolution of 200 ppi despite the fact that the photodiode layer is one continuous layer and is non-pixelated. Low processing temperatures are another key advantage since they can be fabricated on plastic substrate. This implies that we can make X-ray detectors on flexible foil. Those

  12. Demonstration of highly reliable nonhermetic planar InGaAs/InP photodiodes

    NASA Astrophysics Data System (ADS)

    Osenbach, John W.; Evanosky, T. L.; Phatak, Suniel B.; Comizzoli, Robert B.; Chand, Naresh

    1996-01-01

    Reliable non-hermetic photodiodes are expected to reduce the cost of optoelectronics used in fiber to the home and cable TV system. However, all reports to date indicate non-hermetic InGaAs/InP photodiodes do not have sufficient reliability for use in the systems. In this paper, we report the first data that conclusively shows, properly designed and manufactured non- hermetic InGaAs/InP photodiodes can be made with reliability sufficient to use in telecommunication systems. We have produced non-hermetic photodiodes whose hazard rate at 15 years of field use at 45 degrees Celsius and 50% RH is less than 100 FITs, the requirement for telecommunication systems.

  13. Hybridization of a sigma-delta-based CMOS hybrid detector

    NASA Astrophysics Data System (ADS)

    Kolb, K. E.; Stoffel, N. C.; Douglas, B.; Maloney, C. W.; Raisanen, A. D.; Ashe, B.; Figer, D. F.; Tamagawa, T.; Halpern, B.; Ignjatovic, Zeljko

    2010-07-01

    The Rochester Imaging Detector Laboratory, University of Rochester, Infotonics Technology Center, and Jet Process Corporation developed a hybrid silicon detector with an on-chip sigma-delta (ΣΔ) ADC. This paper describes the process and reports the results of developing a fabrication process to robustly produce high-quality bump bonds to hybridize a back-illuminated detector with its ΣΔ ADC. The design utilizes aluminum pads on both the readout circuit and the photodiode array with interconnecting indium bumps between them. The development of the bump bonding process is discussed, including specific material choices, interim process structures, and final functionality. Results include measurements of bond integrity, cross-wafer uniformity of indium bumps, and effects of process parameters on the final product. Future plans for improving the bump bonding process are summarized.

  14. High quality MgB2 thick films and large-area films fabricated by hybrid physical chemical vapor deposition with a pocket heater

    NASA Astrophysics Data System (ADS)

    Wang, S. F.; Chen, Ke; Lee, C.-H.; Soukiassian, A.; Lamborn, D. R.; DeFrain, R.; Redwing, J. M.; Li, Qi; Schlom, D. G.; Xi, X. X.

    2008-08-01

    A hybrid physical-chemical vapor deposition process using a pocket heater was developed for the growth of high quality epitaxial large-area MgB2 thin films and c-axis textured MgB2 thick films. This technique is able to independently control the substrate and Mg source temperatures and maintain sufficient Mg overpressure to ensure phase stability. The two-inch large-area MgB2 thin films showed uniform superconducting properties with the superconducting transition temperature Tc of about 40 K, residual resistivity ratio (RRR) of about 10, and critical current density Jc of about 107 A cm-2 (0 T, 5 K). The thick films (~10 µm) on sapphire substrates showed a maximum Tc of 40 K and RRR of 15, and a Jc of 1.6 × 106 A cm-2 at low applied magnetic fields even at 20 K. High quality thick films also have been obtained on metal substrates.

  15. Large Area Nano-transfer Printing of Sub-50-nm Metal Nanostructures Using Low-cost Semi-flexible Hybrid Templates

    NASA Astrophysics Data System (ADS)

    Nagel, Robin D.; Haeberle, Tobias; Schmidt, Morten; Lugli, Paolo; Scarpa, Giuseppe

    2016-03-01

    In this work, we present a method for printing metal micro- and nanopatterns down to sub-50-nm feature sizes using replicated, defect-tolerant stamps made out of OrmoStamp®; material. The relevant parameters for a successful transfer over large areas were investigated and yields above 99 % have been achieved. Comparing our results to conventional nano-transfer printing using PDMS stamps, we find that the more rigid hybrid polymer used here prevents unintended transfer from interspaces between structures of large distance due to roof collapse and deformation of nano-sized structures due to lateral collapse. Yet, our stamps are flexible enough to ensure intimate contact with the underlying substrate over large areas even in the presence of defect particles. Additionally, the presented patterning technique is resist-, solvent-, and chemical-free and is therefore ideally suited for applications in organic nanoelectronics where standard nanostructuring methods can harm or destroy the organic material.

  16. Large Area Nano-transfer Printing of Sub-50-nm Metal Nanostructures Using Low-cost Semi-flexible Hybrid Templates.

    PubMed

    Nagel, Robin D; Haeberle, Tobias; Schmidt, Morten; Lugli, Paolo; Scarpa, Giuseppe

    2016-12-01

    In this work, we present a method for printing metal micro- and nanopatterns down to sub-50-nm feature sizes using replicated, defect-tolerant stamps made out of OrmoStamp®; material. The relevant parameters for a successful transfer over large areas were investigated and yields above 99 % have been achieved. Comparing our results to conventional nano-transfer printing using PDMS stamps, we find that the more rigid hybrid polymer used here prevents unintended transfer from interspaces between structures of large distance due to roof collapse and deformation of nano-sized structures due to lateral collapse. Yet, our stamps are flexible enough to ensure intimate contact with the underlying substrate over large areas even in the presence of defect particles. Additionally, the presented patterning technique is resist-, solvent-, and chemical-free and is therefore ideally suited for applications in organic nanoelectronics where standard nanostructuring methods can harm or destroy the organic material. PMID:26976429

  17. Application of a photodiode-array optical turbulence sensor to wind studies in complex terrain

    SciTech Connect

    Porch, W.M.; Green, T.J.

    1980-04-01

    A digital photodiode-array optical turbulence sensor was used to gather data simultaneously with analog optical anemometer measurements during the July 1979 ASCOT experiment. This system provided useful information regarding the uniformity of optical turbulence used by the optical anemometer to derive cross-path wind speeds. Wind speeds derived from digital analysis of the photodiode-array intensities also provided an independent measure of the cross-path wind speed. Close agreement was found between these two measures of the wind.

  18. Soft X-ray detection and photon counting spectroscopy with commercial 4H-SiC Schottky photodiodes

    NASA Astrophysics Data System (ADS)

    Zhao, S.; Gohil, T.; Lioliou, G.; Barnett, A. M.

    2016-09-01

    The results of electrical characterisation and X-ray detection measurements of two different active area (0.06 mm2 and 0.5 mm2) commercial 4H-SiC Schottky photodiodes at room temperature are reported. The devices exhibited low dark currents (less than 10 pA) even at a high electric field strengths (403 kV/cm for 0.06 mm2 diodes; 227 kV/cm for 0.5 mm2 diodes). The results of the X-ray measurements indicate that the diodes can be used as photon counting spectroscopic X-ray detectors with modest energy resolutions: FWHM at 5.9 keV of 1.8 keV and 3.3 keV, for the 0.06 mm2 and 0.5 mm2 devices, respectively. Noise analysis of the photodiodes coupled to a custom low noise charge sensitive preamplifier is also presented.

  19. Epitaxial HgCdTe/CdTe Photodiodes For The 1 -3 μm Spectral Region

    NASA Astrophysics Data System (ADS)

    Shin, S. H.; Pasko, J. G.; Cheung, D. T.

    1981-07-01

    Hgi-xCdxTe epitaxial layers have been successfully grown in various compositions, for 1-3 μm applications. n+/p junctions are formed either by a standard B-implantation into as-grown p-type layers or by doubly grown p- and n-layers. The SWIR HgCdTe photodiodes exhibit quantum efficiencies of 55-65% without AR coating. For the diodes with 1.39 μm cut-off at room temperature, the zero bias detector resistance-area (RoA) product is 4 x 10 4 Ω-cm2, and the dark current density is ~ 1 x 10 -4 A/cm2 at half-breakdown voltage. The same values of ~ 104 Ω-cm2 RoA products have also been measured for 2.4 μm cut-off photodiodes at 195K. The energy gap and temperature dependence of RoA product is in excellent agreement with the bulk limited generation-recombination model. The breakdown voltages of SWIR diodes vary from 12 volts to greater than 130 volts, depending on the Cd composition (x) and base carrier concentrations.

  20. Nano-Multiplication-Region Avalanche Photodiodes and Arrays

    NASA Technical Reports Server (NTRS)

    Zheng, Xinyu; Pain, Bedabrata; Cunningham, Thomas

    2008-01-01

    Nano-multiplication-region avalanche photodiodes (NAPDs), and imaging arrays of NAPDs integrated with complementary metal oxide/semiconductor (CMOS) active-pixel-sensor integrated circuitry, are being developed for applications in which there are requirements for high-sensitivity (including photoncounting) detection and imaging at wavelengths from about 250 to 950 nm. With respect to sensitivity and to such other characteristics as speed, geometric array format, radiation hardness, power demand of associated circuitry, size, weight, and robustness, NAPDs and arrays thereof are expected to be superior to prior photodetectors and arrays including CMOS active-pixel sensors (APSs), charge-coupled devices (CCDs), traditional APDs, and microchannelplate/ CCD combinations. Figure 1 depicts a conceptual NAPD array, integrated with APS circuitry, fabricated on a thick silicon-on-insulator wafer (SOI). Figure 2 presents selected aspects of the structure of a typical single pixel, which would include a metal oxide/semiconductor field-effect transistor (MOSFET) integrated with the NAPD. The NAPDs would reside in silicon islands formed on the buried oxide (BOX) layer of the SOI wafer. The silicon islands would be surrounded by oxide-filled insulation trenches, which, together with the BOX layer, would constitute an oxide embedding structure. There would be two kinds of silicon islands: NAPD islands for the NAPDs and MOSFET islands for in-pixel and global CMOS circuits. Typically, the silicon islands would be made between 5 and 10 m thick, but, if necessary, the thickness could be chosen outside this range. The side walls of the silicon islands would be heavily doped with electron-acceptor impurities (p+-doped) to form anodes for the photodiodes and guard layers for the MOSFETs. A nanoscale reach-through structure at the front (top in the figures) central position of each NAPD island would contain the APD multiplication region. Typically, the reach-through structure would be

  1. Readout circuitry for continuous high-rate photon detection with arrays of InP Geiger-mode avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Frechette, Jonathan; Grossmann, Peter J.; Busacker, David E.; Jordy, George J.; Duerr, Erik K.; McIntosh, K. Alexander; Oakley, Douglas C.; Bailey, Robert J.; Ruff, Albert C.; Brattain, Michael A.; Funk, Joseph E.; MacDonald, Jason G.; Verghese, Simon

    2012-06-01

    An asynchronous readout integrated circuit (ROIC) has been developed for hybridization to a 32x32 array of single-photon sensitive avalanche photodiodes (APDs). The asynchronous ROIC is capable of simultaneous detection and readout of photon times of arrival, with no array blind time. Each pixel in the array is independently operated by a finite state machine that actively quenches an APD upon a photon detection event, and re-biases the device into Geiger mode after a programmable hold-off time. While an individual APD is in hold-off mode, other elements in the array are biased and available to detect photons. This approach enables high pixel refresh frequency (PRF), making the device suitable for applications including optical communications and frequency-agile ladar. A built-in electronic shutter that de-biases the whole array allows the detector to operate in a gated mode or allows for detection to be temporarily disabled. On-chip data reduction reduces the high bandwidth requirements of simultaneous detection and readout. Additional features include programmable single-pixel disable, region of interest processing, and programmable output data rates. State-based on-chip clock gating reduces overall power draw. ROIC operation has been demonstrated with hybridized InP APDs sensitive to 1.06-μm and 1.55-μm wavelength, and fully packaged focal plane arrays (FPAs) have been assembled and characterized.

  2. Design of HgCdTe heterojunction photodiodes on Si substrate

    NASA Astrophysics Data System (ADS)

    Zhang, P.; Ye, Z. H.; Chen, Y. Y.; Lin, C.; Hu, X. N.; Ding, R. J.; He, L.

    2014-05-01

    An innovative heterojunction photodiode structure in HgCdTe-on-Si long-wavelength (LW) infrared focal plane array (IRFPA) detector is investigated in this paper. The quantum efficiency and the photoresponse of devices have been numerically simulated, using Crosslight Technology Computer Aided Design (TCAD) software. Simulation results indicate that in contrast to the p+-on-n homojunction photodiode, the heterojunction photodiode effectively suppresses the crosstalk between adjacent pixels and interface recombination between HgCdTe active region and buffer layer on Si substrate. And in the range of the LW-band, the quantum efficiency of the heterojunction photodiode increases by 35.5%. Furthermore, the heterojunction photodiode acquires the narrow-band response spectrum desired in the application of the LW IRFPA detectors as the p+-on-n homojunction photodiode with the optical filter. Finally, the smaller bulk resistance of its heavily doped N-type layer ensures the uniformity of the pixel series resistance in the large format IRFPAs.

  3. Characterization of Advanced Avalanche Photodiodes for Water Vapor Lidar Receivers

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Halama, Gary E.; DeYoung, Russell J.

    2000-01-01

    Development of advanced differential absorption lidar (DIAL) receivers is very important to increase the accuracy of atmospheric water vapor measurements. A major component of such receivers is the optical detector. In the near-infrared wavelength range avalanche photodiodes (APD's) are the best choice for higher signal-to-noise ratio, where there are many water vapor absorption lines. In this study, characterization experiments were performed to evaluate a group of silicon-based APD's. The APD's have different structures representative of different manufacturers. The experiments include setups to calibrate these devices, as well as characterization of the effects of voltage bias and temperature on the responsivity, surface scans, noise measurements, and frequency response measurements. For each experiment, the setup, procedure, data analysis, and results are given and discussed. This research was done to choose a suitable APD detector for the development of an advanced atmospheric water vapor differential absorption lidar detection system operating either at 720, 820, or 940 nm. The results point out the benefits of using the super low ionization ratio (SLIK) structure APD for its lower noise-equivalent power, which was found to be on the order of 2 to 4 fW/Hz(sup (1/2)), with an appropriate optical system and electronics. The water vapor detection systems signal-to-noise ratio will increase by a factor of 10.

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

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Davidson, Frederic M.

    1991-01-01

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

  5. Development of high gain avalanche photodiodes for UV imaging applications

    NASA Astrophysics Data System (ADS)

    Sood, Ashok K.; Zeller, John W.; Welser, Roger E.; Puri, Yash R.; Dupuis, Russell D.; Ji, Mi-Hee; Kim, Jeomoh; Detchprohm, Theeradetch; Dhar, Nibir K.; Lewis, Jay S.; Peters, Roy L.

    2015-08-01

    High-resolution imaging in ultraviolet (UV) bands has many applications in defense and commercial systems. The shortest wavelength is desired for increased spatial resolution, which allows for small pixels and large formats. The next frontier is to develop UV avalanche photodiode (UV-APD) arrays with high gain to demonstrate high-resolution imaging. We compare performance characteristics of front-illuminated Al0.05Ga0.95N UV-APDs grown on a free-standing (FS) GaN substrate and a GaN/sapphire template. UV-APDs grown on a FS-GaN substrate show lower dark current densities for all fabricated mesa sizes than similar UV-APDs grown on a GaN/sapphire template. In addition, stable avalanche gain higher than 5×105 and a significant increase in the responsivity of UV-APDs grown on a FS-GaN substrate are observed as a result of avalanche multiplication at high reverse bias. We believe that the high crystalline quality of Al0.05Ga0.95N UVAPDs grown on a FS-GaN substrate with low dislocation density is responsible for the observed improvement of low leakage currents, high performance photodetector characteristics, and reliability of the devices.

  6. Nanostructured organic-inorganic photodiodes with high rectification ratio.

    PubMed

    Karan, Santanu; Mallik, Biswanath

    2008-12-10

    High quality organic-inorganic heterojunction photodiodes based on nanostructured copper (II) phthalocyanine (CuPc) and intrinsic zinc oxide (i-ZnO) have been fabricated. The i-ZnO thin films/layers were grown by RF magnetron sputtering on clean indium tin oxide (ITO) coated glass substrates. These films have been characterized by optical absorption and field emission scanning electron microscopy (FESEM). CuPc thin films deposited at room temperature on i-ZnO have exhibited a change in their surface morphology with the post-deposition annealing temperature under normal atmosphere. The electrical dark conductivity and the photoconductivity of ITO/i-ZnO/CuPc/Au sandwich structures have been measured under various photoexcitation intensities using a xenon light source. The devices have shown excellent reproducibility of their electrical characteristics and high rectification ratios. The highest rectification ratio is nearly 831 calculated above the threshold voltage at room temperature for the sample annealed at 250 °C (i.e. Pc 250). The effects of the annealing temperature of CuPc on the surface morphology, rectification ratio, and optical properties have been discussed. PMID:21730664

  7. ASIC Readout Circuit Architecture for Large Geiger Photodiode Arrays

    NASA Technical Reports Server (NTRS)

    Vasile, Stefan; Lipson, Jerold

    2012-01-01

    The objective of this work was to develop a new class of readout integrated circuit (ROIC) arrays to be operated with Geiger avalanche photodiode (GPD) arrays, by integrating multiple functions at the pixel level (smart-pixel or active pixel technology) in 250-nm CMOS (complementary metal oxide semiconductor) processes. In order to pack a maximum of functions within a minimum pixel size, the ROIC array is a full, custom application-specific integrated circuit (ASIC) design using a mixed-signal CMOS process with compact primitive layout cells. The ROIC array was processed to allow assembly in bump-bonding technology with photon-counting infrared detector arrays into 3-D imaging cameras (LADAR). The ROIC architecture was designed to work with either common- anode Si GPD arrays or common-cathode InGaAs GPD arrays. The current ROIC pixel design is hardwired prior to processing one of the two GPD array configurations, and it has the provision to allow soft reconfiguration to either array (to be implemented into the next ROIC array generation). The ROIC pixel architecture implements the Geiger avalanche quenching, bias, reset, and time to digital conversion (TDC) functions in full-digital design, and uses time domain over-sampling (vernier) to allow high temporal resolution at low clock rates, increased data yield, and improved utilization of the laser beam.

  8. Characterization of midwave infrared InSb avalanche photodiode

    SciTech Connect

    Abautret, J. Evirgen, A.; Perez, J. P.; Christol, P.; Rothman, J.; Cordat, A.

    2015-06-28

    This paper focuses on the InSb material potential for the elaboration of Avalanche Photodiodes (APD) for high performance infrared imaging applications, both in passive or active mode. The first InSb electron-APD structure was grown by molecular beam epitaxy, processed and electrically characterized. The device performances are at the state of the art for the InSb epi-diode technology, with a dark current density J(−50 mV) = 32 nA/cm{sup 2} at 77 K. Then, a pure electron injection was performed, and an avalanche gain, increasing exponentially, was observed with a gain value near 3 at −4 V at 77 K. The Okuto–Crowell model was used to determine the electron ionization coefficient α(E) in InSb, and the InSb gain behavior is compared with the one of InAs and MCT APDs.

  9. Continuous Holdup Measurements with Silicon P-I-N Photodiodes

    SciTech Connect

    Bell, Z.W.; Oberer, R.B.; Williams, J.A.; Smith, D.E.; Paulus, M.J.

    2002-05-01

    We report on the behavior of silicon P-I-N photodiodes used to perform holdup measurements on plumbing. These detectors differ from traditional scintillation detectors in that no high-voltage is required, no scintillator is used (gamma and X rays are converted directly by the diode), and they are considerably more compact. Although the small size of the diodes means they are not nearly as efficient as scintillation detectors, the diodes' size does mean that a detector module, including one or more diodes, pulse shaping electronics, analog-to-digital converter, embedded microprocessor, and digital interface can be realized in a package (excluding shielding) the size of a pocket calculator. This small size, coupled with only low-voltage power requirement, completely solid-state realization, and internal control functions allows these detectors to be strategically deployed on a permanent basis, thereby reducing or eliminating the need for manual holdup measurements. In this paper, we report on the measurement of gamma and X rays from {sup 235}U and {sup 238}U contained in steel pipe. We describe the features of the spectra, the electronics of the device and show how a network of them may be used to improve estimates of inventory in holdup.

  10. Nanostructured organic inorganic photodiodes with high rectification ratio

    NASA Astrophysics Data System (ADS)

    Karan, Santanu; Mallik, Biswanath

    2008-12-01

    High quality organic-inorganic heterojunction photodiodes based on nanostructured copper (II) phthalocyanine (CuPc) and intrinsic zinc oxide (i-ZnO) have been fabricated. The i-ZnO thin films/layers were grown by RF magnetron sputtering on clean indium tin oxide (ITO) coated glass substrates. These films have been characterized by optical absorption and field emission scanning electron microscopy (FESEM). CuPc thin films deposited at room temperature on i-ZnO have exhibited a change in their surface morphology with the post-deposition annealing temperature under normal atmosphere. The electrical dark conductivity and the photoconductivity of ITO/i-ZnO/CuPc/Au sandwich structures have been measured under various photoexcitation intensities using a xenon light source. The devices have shown excellent reproducibility of their electrical characteristics and high rectification ratios. The highest rectification ratio is nearly 831 calculated above the threshold voltage at room temperature for the sample annealed at 250 °C (i.e. Pc 250). The effects of the annealing temperature of CuPc on the surface morphology, rectification ratio, and optical properties have been discussed.

  11. Measurement of Radiation - Light Field Congruence using a Photodiode Array

    NASA Astrophysics Data System (ADS)

    Balderson, Michael J.

    Improved treatment techniques in radiation therapy provide incentive to reduce treatment margins, thereby increasing the necessity for more accurate geometrical setup of the linear accelerator and accompanying components. In this thesis, we describe the development of a novel device that enables precise and automated measurement of radiation-light field congruence of medical linear accelerators for the purpose of improving setup accuracy, and standardizing repeated quality control activities. The device consists of a silicon photodiode array, an evaluation board, a data acquisition card, and a laptop. Using the device, we show that the radiation-light field congruence for both 6 and 15 MV beams is within 2 mm on a Varian Clinac 21 EX medical linear accelerator. Because measurements are automated, ambiguities resulting from observer variability are removed, greatly improving the reproducibility of measurements over time and across observers. We expect the device to be useful in providing consistent measurements on linear accelerators used for stereotactic radiosurgery, during the commissioning of new linear accelerators, and as an alternative to film or other commercially available devices for performing monthly or annual quality control checks.

  12. High current density and longtime stable field electron transfer from large-area densely arrayed graphene nanosheet-carbon nanotube hybrids.

    PubMed

    Deng, Jian-Hua; Cheng, Lin; Wang, Fan-Jie; Li, Guo-Zheng; Li, De-Jun; Cheng, Guo-An

    2014-12-10

    Achieving high current and longtime stable field emission from large area (larger than 1 mm(2)), densely arrayed emitters is of great importance in applications for vacuum electron sources. We report here the preparation of graphene nanosheet-carbon nanotube (GNS-CNT) hybrids by following a process of iron ion prebombardment on Si wafers, catalyst-free growth of GNSs on CNTs, and high-temperature annealing. Structural observations indicate that the iron ion prebombardment influences the growth of CNTs quite limitedly, and the self-assembled GNSs sparsely distributed on the tips of CNTs with their sharp edges unfolded outside. The field emission study indicates that the maximum emission current density (Jmax) is gradually promoted after these treatments, and the composition with GNSs is helpful for decreasing the operation fields of CNTs. An optimal Jmax up to 85.10 mA/cm(2) is achieved from a 4.65 mm(2) GNS-CNT sample, far larger than 7.41 mA/cm(2) for the as-grown CNTs. This great increase of Jmax is ascribed to the reinforced adhesion of GNS-CNT hybrids to substrates. We propose a rough calculation and find that this adhesion is promoted by 7.37 times after the three-step processing. We consider that both the ion prebombardment produced rough surface and the wrapping of CNT foot by catalyst residuals during thermal processing are responsible for this enhanced adhesion. Furthermore, the three-step prepared GNS-CNT hybrids present excellent field emission stability at high emission current densities (larger than 20 mA/cm(2)) after being perfectly aged. PMID:25335851

  13. Enhanced Red and Near Infrared Detection in Flow Cytometry Using Avalanche Photodiodes

    PubMed Central

    Lawrence, William G.; Varadi, Gyula; Entine, Gerald; Podniesinski, Edward; Wallace, Paul K.

    2008-01-01

    Background Polychromatic flow cytometry enables detailed identification of cell phenotype using multiple fluorescent parameters. The photomultiplier tubes used to detect fluorescence in current instruments limit the sensitivity in the long wavelength spectral range. We demonstrate the flow cytometric applications of silicon avalanche photodiodes, which have improved red sensitivity and a working fluorescence detection range beyond 1000 nm. Methods A comparison of the wavelength dependent performance of the avalanche photodiode and photomultiplier tube was carried out using pulsed light emitting diode sources, calibrated test beads and biological samples. A breadboard flow cytometer test bench was constructed to compare the performance of photomultiplier tubes and avalanche photodiode detectors. The avalanche photodiode used an additional amplifier stage to match the internal gain of the photomultiplier tube. Results The resolution of the avalanche photodiode and photomultiplier tube was compared for flow cytometry applications using a pulsed light emitting diode source over the 500 nm to 1060 nm spectral range. These measurements showed the relative changes in the signal to noise performance of the APD and PMT over a broad spectral range. Both the avalanche photodiode and photomultiplier tubes were used to measure the signal to noise response for a set of 6 peak calibration beads over the 530 to 800 nm wavelength range. CD4 positive cells labeled with antibody conjugated phycoerythrin or 800 nm quantum dots were identified by simultaneous detection using the avalanche photodiode and the photomultiplier tube. The ratios of the intensities of the CD4− and CD4+ populations were found to be similar for both detectors in the visible wavelengths, but only the avalanche photodiode was able to separate these populations at wavelengths above 800 nm. Conclusions These measurements illustrate the differences in APD and PMT performance at different wavelengths and signal

  14. Organic Photodiodes: The Future of Full Color Detection and Image Sensing.

    PubMed

    Jansen-van Vuuren, Ross D; Armin, Ardalan; Pandey, Ajay K; Burn, Paul L; Meredith, Paul

    2016-06-01

    Major growth in the image sensor market is largely as a result of the expansion of digital imaging into cameras, whether stand-alone or integrated within smart cellular phones or automotive vehicles. Applications in biomedicine, education, environmental monitoring, optical communications, pharmaceutics and machine vision are also driving the development of imaging technologies. Organic photodiodes (OPDs) are now being investigated for existing imaging technologies, as their properties make them interesting candidates for these applications. OPDs offer cheaper processing methods, devices that are light, flexible and compatible with large (or small) areas, and the ability to tune the photophysical and optoelectronic properties - both at a material and device level. Although the concept of OPDs has been around for some time, it is only relatively recently that significant progress has been made, with their performance now reaching the point that they are beginning to rival their inorganic counterparts in a number of performance criteria including the linear dynamic range, detectivity, and color selectivity. This review covers the progress made in the OPD field, describing their development as well as the challenges and opportunities. PMID:27111541

  15. Compact low-noise preamplifier for noise spectroscopy with biased photodiodes in cargo inspection systems

    NASA Astrophysics Data System (ADS)

    Benetti, Bob; Langeveld, Willem G. J.

    2013-09-01

    Noise Spectroscopy, a.k.a. Z-determination by Statistical Count-rate ANalysis (Z-SCAN), is a statistical technique to determine a quantity called the "noise figure" from digitized waveforms of pulses of transmitted x-rays in cargo inspection systems. Depending only on quantities related to the x-ray energies, it measures a characteristic of the transmitted x-ray spectrum, which depends on the atomic number, Z, of the material penetrated. The noise figure can thus be used for material separation. In an 80-detector prototype, scintillators are used with large-area photodiodes biased at 80V and digitized using 50-MSPS 12-bit ADC boards. We present an ultra-compact low-noise preamplifier design, with one high-gain and one low-gain channel per detector for improved dynamic range. To achieve adequate detection sensitivity and spatial resolution each dual-gain preamplifier channel must fit within a 12.7 mm wide circuit board footprint and maintain adequate noise immunity to conducted and radiated interference from adjacent channels. The novel design included iterative SPICE analysis of transient response, dynamic range, frequency response, and noise analysis to optimize the selection and configuration of amplifiers and filter response. We discuss low-noise active and passive components and low-noise techniques for circuit board layout that are essential to achieving the design goals, and how the completed circuit board performed in comparison to the predicted responses.

  16. Current-mode CMOS hybrid image sensor

    NASA Astrophysics Data System (ADS)

    Benyhesan, Mohammad Kassim

    Digital imaging is growing rapidly making Complimentary Metal-Oxide-Semi conductor (CMOS) image sensor-based cameras indispensable in many modern life devices like cell phones, surveillance devices, personal computers, and tablets. For various purposes wireless portable image systems are widely deployed in many indoor and outdoor places such as hospitals, urban areas, streets, highways, forests, mountains, and towers. However, the increased demand on high-resolution image sensors and improved processing features is expected to increase the power consumption of the CMOS sensor-based camera systems. Increased power consumption translates into a reduced battery life-time. The increased power consumption might not be a problem if there is access to a nearby charging station. On the other hand, the problem arises if the image sensor is located in widely spread areas, unfavorable to human intervention, and difficult to reach. Given the limitation of energy sources available for wireless CMOS image sensor, an energy harvesting technique presents a viable solution to extend the sensor life-time. Energy can be harvested from the sun light or the artificial light surrounding the sensor itself. In this thesis, we propose a current-mode CMOS hybrid image sensor capable of energy harvesting and image capture. The proposed sensor is based on a hybrid pixel that can be programmed to perform the task of an image sensor and the task of a solar cell to harvest energy. The basic idea is to design a pixel that can be configured to exploit its internal photodiode to perform two functions: image sensing and energy harvesting. As a proof of concept a 40 x 40 array of hybrid pixels has been designed and fabricated in a standard 0.5 microm CMOS process. Measurement results show that up to 39 microW of power can be harvested from the array under 130 Klux condition with an energy efficiency of 220 nJ /pixel /frame. The proposed image sensor is a current-mode image sensor which has several

  17. RDA Requirements For Optimum Hybrid Focal Plane Performance

    NASA Astrophysics Data System (ADS)

    Grossman, S. B.; Emmons, R. B.; Hawkins, S. R.

    1982-06-01

    In analyzing the performance of direct-injected hybrid focal plane arrays, many factors must be consiaered in determining the minimum detector resistance-area product RDA neces-sary to obtain background-limited performance (BLIP) and good array uniformity. In photo-aioue arrays, a necessary but not sufficient condition is that noise due to the diode generation-recombination and diffusion currents are less than the background photon shot noise. Tnis places a minimum requirement on the magnitude of RoA, the zero bias resistance area product. In addition, there are generally much more stringent requirements on RDA uue to input MOSFET l/f noise and threshold variations which exceed the single detector RoA requirement for BLIP operation at a given background. In general, the input thresnolu variations require that the photodiodes be somewhat back-biased. This produces a substantially higner average RDA at the expense of higher detector l/f noise due to surface leakage. In tnis study we have investigated the detector impedance requirements in terms of tne injection efficiency, threshold nonuniformities, the input MOSFET excess (l/f) noise, and tne detector excess noise. For state-of-the-art parameters, it was determined tnat tne input MOSFET l/f noise always dominates the other elements in determining the required detector impeaance:k

  18. Wavelength-band-tuning photodiodes by using various metallic nanoparticles.

    PubMed

    Hwang, J D; Chan, Y D; Chou, T C

    2015-11-20

    Wavelength-band tuning was easily achieved in this work by depositing various metallic nanoparticles (NPs) on silicon p-n junction photodiodes (PDs). The normalization spectrum of the PDs deposited with gold (Au) NPs reveals a high-wavelength pass characteristic; the PDs with silver (Ag) NPs coating behave as a low-wavelength pass, and the PDs with Au/Ag bimetallic NPs appear as a band-wavelength pass PD with a full width at half maximum of 450 ∼ 630 nm. The issue of wavelength-band tuning is due to the different plasmonic resonance wavelengths associated with various metallic NPs. The extinction plot shows the Au NPs have a longer resonant wavelength of about 545 nm, leading to the incident light with a wavelength near or longer than 545 nm scattered by the Au NPs, hence a high-wavelength pass PD. The PDs with Ag NPs, due to the Ag NPs, exhibit a short resonant wavelength of 430 nm, and the short-wavelength incident light is absorbed near the silicon (Si) surface, where the Ag NPs is atop it. The shorter-wavelength incident light is enhanced by the plasmonic resonance of Ag NPs, making a low-wavelength PD. The Au/Ag NPs presents a resonant wavelength of 500 nm between the Au and Ag NPs. For the incident light with a wavelength close to 500 nm, a constructive interference causes a substantial increase in the local electromagnetic field, hence leading to a band-wavelength pass PD. PMID:26508114

  19. Advanced active quenching circuits for single-photon avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Stipčević, M.; Christensen, B. G.; Kwiat, P. G.; Gauthier, D. J.

    2016-05-01

    Commercial photon-counting modules, often based on actively quenched solid-state avalanche photodiode sensors, are used in wide variety of applications. Manufacturers characterize their detectors by specifying a small set of parameters, such as detection efficiency, dead time, dark counts rate, afterpulsing probability and single photon arrival time resolution (jitter), however they usually do not specify the conditions under which these parameters are constant or present a sufficient description. In this work, we present an in-depth analysis of the active quenching process and identify intrinsic limitations and engineering challenges. Based on that, we investigate the range of validity of the typical parameters used by two commercial detectors. We identify an additional set of imperfections that must be specified in order to sufficiently characterize the behavior of single-photon counting detectors in realistic applications. The additional imperfections include rate-dependence of the dead time, jitter, detection delay shift, and "twilighting." Also, the temporal distribution of afterpulsing and various artifacts of the electronics are important. We find that these additional non-ideal behaviors can lead to unexpected effects or strong deterioration of the system's performance. Specifically, we discuss implications of these new findings in a few applications in which single-photon detectors play a major role: the security of a quantum cryptographic protocol, the quality of single-photon-based random number generators and a few other applications. Finally, we describe an example of an optimized avalanche quenching circuit for a high-rate quantum key distribution system based on time-bin entangled photons.

  20. Hybrid and electric low-noise cars cause an increase in traffic accidents involving vulnerable road users in urban areas.

    PubMed

    Brand, Stephan; Petri, Maximilian; Haas, Philipp; Krettek, Christian; Haasper, Carl

    2013-01-01

    Due to resource scarcity, the number of low-noise and electric cars is expected to increase rapidly. The frequent use of these cars will lead to a significant reduction of traffic related noise and pollution. On the other hand, due to the adaption and conditioning of vulnerable road users the number of traffic accidents involving pedestrians and bicyclists is postulated to increase as well. Children, older people with reduced eyesight and the blind are especially reliant on a combination of acoustic and visual warning signals with approaching or accelerating vehicles. This is even more evident in urban areas where the engine sound is the dominating sound up to 30 kph (kilometres per hour). Above this, tyre-road interaction is the main cause of traffic noise. With the missing typical engine sound a new sound design is necessary to prevent traffic accidents in urban areas. Drivers should not be able to switch the sound generator off. PMID:23083396

  1. A room temperature LSO/PIN photodiode PET detector module that measures depth of interaction

    SciTech Connect

    Moses, W.W.; Derenzo, S.E.; Melcher, C.L.; Manente, R.A.

    1994-11-01

    We present measurements of a 4 element PET detector module that uses a 2{times}2 array of 3 mm square PIN photodiodes to both measure the depth of interaction (DOI) and identify the crystal of interaction. Each photodiode is coupled to one end of a 3{times}3{times}25 mm LSO crystal, with the opposite ends of all 4 crystals attached to a single PMT that provides a timing signal and initial energy discrimination. Each LSO crystal is coated with a {open_quotes}lossy{close_quotes} reflector, so the ratio of light detected in the photodiode and PMT depends on the position of interaction in the crystal, and is used to determine this position on an event by event basis. This module is operated at +25{degrees}C with a photodiode amplifier peaking time of 2 {mu}s. When excited by a collimated beam of 511 keV photons at the photodiode end of the module (i.e. closest to the patient), the DOI resolution is 4 mm fwhm and the crystal of interaction is identified correctly 95% of the time. When excited at the opposite end of the module, the DOI resolution is 13 mm fwhm and the crystal of interaction is identified correctly 73% of the time. The channel to channel variations in performance are minimal.

  2. Longterm changes of silicon photodiodes and their use for photometric standardization.

    PubMed

    Eppeldauer, G

    1990-05-20

    A secondary standard silicon photodiode matched with a V-lambda filter was calibrated against primary standard, self-calibrated inversion layer silicon photodiodes, to achieve a high accuracy photometer, according to the new definition of the canadela (the photometric base unit). The measured several percent/year specular spectral reflectance change of the windowless primary standard photodiodes was eliminated by their repeated self-calibration. This self-calibration also eliminated the measured several tenth of a percent/year spectral response change of the secondary standard silicon photodiode. The secondary standard detector could be a nonunity quantum efficiency light detector. The spectral response calibration of the V-lambda matched detector of medium spectral mismatch (f(1)= 3.0%) against the absolute spectral responses of three self-calibrated photodiodes resulted in a standard deviation of 0.17% in luminous flux (lumen) calibration. Also illuminance (lux) and light intensity (candela) calibrations were derived from the above primary photometric calibration. It is shown that the V-lambda matched photometer with the above spectral calibration can be used for accurate photometric measurements for all kinds of light sources of known spectral power distribution. PMID:20563163

  3. 64-element photodiode array for scintillation detection of x-rays

    NASA Astrophysics Data System (ADS)

    Wegrzecki, Maciej; Wolski, Dariusz; Bar, Jan; Budzyński, Tadeusz; Chłopik, Arkadiusz; Grabiec, Piotr; Kłos, Helena; Panas, Andrzej; Piotrowski, Tadeusz; Słysz, Wojciech; Stolarski, Maciej; Szmigiel, Dariusz; Wegrzecka, Iwona; Zaborowski, Michał

    2014-08-01

    The paper presents the design, technology and parameters of a new, silicon 64-element linear photodiode array developed at the Institute of Electron Technology (ITE) for the detection of scintillations emitted by CsI scintillators (λ≈550 nm). The arrays are used in a device for examining the content of containers at border crossings under development at the National Centre for Nuclear Research. Two arrays connected with a scintillator block (128 CsI scintillators) form a 128-channel detection module. The array consists of 64 epiplanar photodiode structures (5.1 × 7.2 mm) and a 5.3 mm module. p+-ν-n+ photodiode structures are optimised for the detection of radiation of λ≈ 550 nm wavelength with no voltage applied (photovoltaic mode). The structures are mounted on an epoxy-glass laminate substrate, copper-clad on both sides, on which connections with a common anode and separate cathode leads are located. The photosensitive surface of photodiodes is covered with a special silicone gel, which protects photodiodes against the mechanical impact of scintillators

  4. Performances of photodiode detectors for top and bottom counting detectors of ISS-CREAM experiment

    NASA Astrophysics Data System (ADS)

    Hyun, H. J.; Anderson, T.; Angelaszek, D.; Baek, S. J.; Copley, M.; Coutu, S.; Han, J. H.; Huh, H. G.; Hwang, Y. S.; Im, S.; Jeon, H. B.; Kah, D. H.; Kang, K. H.; Kim, H. J.; Kim, K. C.; Kwashnak, K.; Lee, J.; Lee, M. H.; Link, J. T.; Lutz, L.; Mitchell, J. W.; Nutter, S.; Ofoha, O.; Park, H.; Park, I. H.; Park, J. M.; Patterson, P.; Seo, E. S.; Wu, J.; Yoon, Y. S.

    2015-07-01

    The Cosmic Ray Energetics and Mass (CREAM) experiment at the International Space Station (ISS) aims to elucidate the source and acceleration mechanisms of high-energy cosmic rays by measuring the energy spectra from protons to iron. The instrument is planned for launch in 2015 at the ISS, and it comprises a silicon charge detector, a carbon target, top and bottom counting detectors, a calorimeter, and a boronated scintillator detector. The top and bottom counting detectors are developed for separating the electrons from the protons, and each of them comprises a plastic scintillator and a 20×20 silicon photodiode array. Each photodiode is 2.3 cm×2.3 cm in size and exhibits good electrical characteristics. The leakage current is measured to be less than 20 nA/cm2 at an operating voltage. The signal-to-noise ratio is measured to be better than 70 using commercial electronics, and the radiation hardness is tested using a proton beam. A signal from the photodiode is amplified by VLSI (very-large-scale integration) charge amp/hold circuits, the VA-TA viking chip. Environmental tests are performed using whole assembled photodiode detectors of a flight version. Herein, we present the characteristics of the developed photodiode along with the results of the environmental tests.

  5. Characterization of GaSb photodiode for gamma-ray detection

    NASA Astrophysics Data System (ADS)

    Juang, Bor-Chau; Prout, David L.; Liang, Baolai; Chatziioannou, Arion F.; Huffaker, Diana L.

    2016-08-01

    We extract the carrier mobility-lifetime products for epitaxially grown GaSb and demonstrate the spectral response to gamma rays of a GaSb p–i–n photodiode with a 2-µm-thick absorption region. Under exposure from 55Fe and 241Am radioactive sources at 140 K, the photodiode exhibits full width at half maximum energy resolutions of 1.238 ± 0.028 and 1.789 ± 0.057 keV at 5.89 and 59.5 keV, respectively. We observe good linearity of the GaSb photodiode across a range of photon energies. The electronic noise and charge trapping noise are measured and shown to be the main components limiting the measured energy resolutions.

  6. High performance waveguide-coupled Ge-on-Si linear mode avalanche photodiodes.

    PubMed

    Martinez, Nicholas J D; Derose, Christopher T; Brock, Reinhard W; Starbuck, Andrew L; Pomerene, Andrew T; Lentine, Anthony L; Trotter, Douglas C; Davids, Paul S

    2016-08-22

    We present experimental results for a selective epitaxially grown Ge-on-Si separate absorption and charge multiplication (SACM) integrated waveguide coupled avalanche photodiode (APD) compatible with our silicon photonics platform. Epitaxially grown Ge-on-Si waveguide-coupled linear mode avalanche photodiodes with varying lateral multiplication regions and different charge implant dimensions are fabricated and their illuminated device characteristics and high-speed performance is measured. We report a record gain-bandwidth product of 432 GHz for our highest performing waveguide-coupled avalanche photodiode operating at 1510nm. Bit error rate measurements show operation with BER< 10-12, in the range from -18.3 dBm to -12 dBm received optical power into a 50 Ω load and open eye diagrams with 13 Gbps pseudo-random data at 1550 nm. PMID:27557187

  7. Indium phosphide-based monolithically integrated PIN waveguide photodiode readout for resonant cantilever sensors

    SciTech Connect

    Siwak, N. P.; Fan, X. Z.; Ghodssi, R.; Kanakaraju, S.; Richardson, C. J. K.

    2014-10-06

    An integrated photodiode displacement readout scheme for a microelectromechanical cantilever waveguide resonator sensing platform is presented. III-V semiconductors are used to enable the monolithic integration of passive waveguides with active optical components. This work builds upon previously demonstrated results by measuring the displacement of cantilever waveguide resonators with on-chip waveguide PIN photodiodes. The on-chip integration of the readout provides an additional 70% improvement in mass sensitivity compared to off-chip photodetector designs due to measurement stability and minimized coupling loss. In addition to increased measurement stability, reduced packaging complexity is achieved due to the simplicity of the readout design. We have fabricated cantilever waveguides with integrated photodetectors and experimentally characterized these cantilever sensors with monolithically integrated PIN photodiodes.

  8. Fast, Deep-Record-Length, Fiber-Coupled Photodiode Imaging Array for Plasma Diagnostics

    NASA Astrophysics Data System (ADS)

    Brockington, Samuel; Case, Andrew; Witherspoon, F. Douglas

    2014-10-01

    HyperV Technologies has been developing an imaging diagnostic comprised of an array of fast, low-cost, long-record-length, fiber-optically-coupled photodiode channels to investigate plasma dynamics and other fast, bright events. By coupling an imaging fiber bundle to a bank of amplified photodiode channels, imagers and streak imagers of 100 to 1000 pixels can be constructed. By interfacing analog photodiode systems directly to commercial analog-to-digital converters and modern memory chips, a prototype 100 pixel array with an extremely deep record length (128 k points at 20 Msamples/s) and 10 bit pixel resolution has already been achieved. HyperV now seeks to extend these techniques to construct a prototype 1000 Pixel framing camera with up to 100 Msamples/sec rate and 10 to 12 bit depth. Preliminary experimental results as well as Phase 2 plans will be discussed. Work supported by USDOE Phase 2 SBIR Grant DE-SC0009492.

  9. Fast, Deep-Record-Length, Fiber-Coupled Photodiode Imaging Array for Plasma Diagnostics

    NASA Astrophysics Data System (ADS)

    Brockington, Samuel; Case, Andrew; Witherspoon, F. Douglas

    2015-11-01

    HyperV Technologies has been developing an imaging diagnostic comprised of an array of fast, low-cost, long-record-length, fiber-optically-coupled photodiode channels to investigate plasma dynamics and other fast, bright events. By coupling an imaging fiber bundle to a bank of amplified photodiode channels, imagers and streak imagers can be constructed. By interfacing analog photodiode systems directly to commercial analog-to-digital converters and modern memory chips, a scalable solution for 100 to 1000 pixel systems with 14 bit resolution and record-lengths of 128k frames has been developed. HyperV is applying these techniques to construct a prototype 1000 Pixel framing camera with up to 100 Msamples/sec rate and 10 to 14 bit depth. Preliminary experimental results as well as future plans will be discussed. Work supported by USDOE Phase 2 SBIR Grant DE-SC0009492.

  10. A 10MHz Fiber-Coupled Photodiode Imaging Array for Plasma Diagnostics

    NASA Astrophysics Data System (ADS)

    Brockington, Samuel; Case, Andrew; Witherspoon, F. Douglas

    2013-10-01

    HyperV Technologies has been developing an imaging diagnostic comprised of arrays of fast, low-cost, long-record-length, fiber-optically-coupled photodiode channels to investigate plasma dynamics and other fast, bright events. By coupling an imaging fiber bundle to a bank of amplified photodiode channels, imagers and streak imagers of 100 to 10,000 pixels can be constructed. By interfacing analog photodiode systems directly to commercial analog to digital convertors and modern memory chips, a prototype pixel with an extremely deep record length (128 k points at 40 Msamples/s) has been achieved for a 10 bit resolution system with signal bandwidths of at least 10 MHz. Progress on a prototype 100 Pixel streak camera employing this technique is discussed along with preliminary experimental results and plans for a 10,000 pixel imager. Work supported by USDOE Phase 1 SBIR Grant DE-SC0009492.

  11. Deep ultraviolet photodiodes based on β-Ga2O3/SiC heterojunction

    NASA Astrophysics Data System (ADS)

    Nakagomi, Shinji; Momo, Toshihiro; Takahashi, Syuhei; Kokubun, Yoshihiro

    2013-08-01

    A deep Ultraviolet (UV) photodiode was fabricated using a heterojunction between β-Ga2O3 with a band gap of 4.9 eV, and 6H-SiC with a band gap of 3.02 eV, and investigated its UV sensitivity. A thin β-Ga2O3 layer (200 nm) was prepared on a p-type 6H-SiC substrate through gallium evaporation in oxygen plasma. The device showed good rectifying properties. Under reverse bias, the current increased linearly with increasing deep-UV light intensity. The responsivity of the photodiode was highest to deep-UV light below a wavelength of 260 nm. The photodiode's response time to deep-UV light was in the order of milliseconds.

  12. Analysis of the photodiode boundary layer transition indicator. LDRD final report

    SciTech Connect

    Kuntz, D.W.; Wilken, A.C.; Payne, J.L.

    1994-06-01

    The photodiode transition indicator is a device which has been successfully used to determine the onset of boundary layer transition on numerous hypersonic flight vehicles. The exact source of the electromagnetic radiation detected by the photodiode at transition was not understood. In some cases early saturation of the device occurred, and the device failed to detect transition. Analyses have been performed to determine the source of the radiation producing the photodiode signal. The results of these analyses indicate that the most likely source of the radiation is blackbody emission from the heatshield material bordering the quartz window of the device. Good agreement between flight data and calculations based on this radiation source has been obtained. Analyses also indicate that the most probable source of the radiation causing early saturation is blackbody radiation from carbon particles which break away from the nosetip during the ablation process.

  13. Indium phosphide-based monolithically integrated PIN waveguide photodiode readout for resonant cantilever sensors

    NASA Astrophysics Data System (ADS)

    Siwak, N. P.; Fan, X. Z.; Kanakaraju, S.; Richardson, C. J. K.; Ghodssi, R.

    2014-10-01

    An integrated photodiode displacement readout scheme for a microelectromechanical cantilever waveguide resonator sensing platform is presented. III-V semiconductors are used to enable the monolithic integration of passive waveguides with active optical components. This work builds upon previously demonstrated results by measuring the displacement of cantilever waveguide resonators with on-chip waveguide PIN photodiodes. The on-chip integration of the readout provides an additional 70% improvement in mass sensitivity compared to off-chip photodetector designs due to measurement stability and minimized coupling loss. In addition to increased measurement stability, reduced packaging complexity is achieved due to the simplicity of the readout design. We have fabricated cantilever waveguides with integrated photodetectors and experimentally characterized these cantilever sensors with monolithically integrated PIN photodiodes.

  14. Photoelectric conversion characteristics of c-Se-based thin-film photodiodes in imaging device

    NASA Astrophysics Data System (ADS)

    Imura, S.; Kikuchi, K.; Miyakawa, K.; Ohtake, H.; Kubota, M.

    2015-06-01

    Herein, we report the use of high-efficiency crystalline-selenium-based (c-Se-based) thin-film heterojunction photodiodes in imaging devices. As a novel experiment, we use an image pickup tube with a photoelectric conversion layer consisting of n-gallium oxide (Ga2O3)/p-c-Se heterojunction photodiodes to obtain high-resolution images at a relatively low applied voltage. We reduce the thickness of the Ga2O3 layer to expand the depletion layer into the c-Se layer at a lower applied voltage. In addition, Sn-doping of the Ga2O3 layer effectively increases the carrier concentration, thereby allowing the photodiode to operate at lower voltage.

  15. Design and fabrication of low-cost reconfigurable microstrip antenna using photodiode as optical switching

    NASA Astrophysics Data System (ADS)

    Kusumawati, E. R.; Pramono, Y. H.; Rubiyanto, A.

    2014-09-01

    Design, fabrication, and characterization prototype of reconfigurable dipole microstrip antenna using photodiode as optical switching have been conducted in the Laboratory for Optical and Microwave Physics Department Faculty of ITS. This paper presents a new reconfigurable antenna design using photodiode as optical switching. In order to be optical switching, photodiode must be illuminated by optical source. The optical source used is Infrared with power 8 mW. Antenna is fabricated in FR-4 substrate which has 1.6 mm thick and 4.8 relative permittivity value. The dimension of the substrate is 131 mm × 21.5 mm × 1.6 mm. The structure of antenna is Coplanar Stripline (CPS) dipole. Measurement is conducted in two state. First state is photodiodes unilluminated Infrared and the second state is illuminated. The measurement result indicate that if condition is not illuminated by Infrared (OFF-state) antenna has resonance frequency of 2010 MHz and 2120 MHz. At frequency 2010 MHz, S11 value -35.7 dB and bandwidth 57 MHz, meanwhile at frequency 2120 MHz, S11 value -17.3 dB and bandwidth 42 MHz. Then if photodiode was illuminated by infrared (ON-state), antenna work at frequency 2007 MHz with S11 value -41.8 dB and bandwidth 61 MHz and 2113 MHz with S11 value -19.4 and bandwidth 47 MHz. There was frequency shifting from 2010 MHz to 2007 MHz and 2120 MHz to 2113 MHz of 5 MHz. At ON state, S11 value also was shifting. There was 6.1 dB and 2.1 dB. Bandwidth at ON-state is wider than OFF state. Microstrip antenna with a reconfigurable optical switching photodiode has several advantages. The advantages are more easily fabricated and the cost is relatively cheaper than the other techniques of optical switching.

  16. Development of Fuses for Protection of Geiger-Mode Avalanche Photodiode Arrays

    NASA Astrophysics Data System (ADS)

    Grzesik, Michael; Bailey, Robert; Mahan, Joe; Ampe, Jim

    2015-11-01

    Current-limiting fuses composed of Ti/Al/Ni were developed for use in Geiger-mode avalanche photodiode arrays for each individual pixel in the array. The fuses were designed to burn out at ˜4.5 × 10-3 A and maintain post-burnout leakage currents less than 10-7 A at 70 V sustained for several minutes. Experimental fuse data are presented and successful incorporation of the fuses into a 256 × 64 pixel InP-based Geiger-mode avalanche photodiode array is reported.

  17. Improved x-ray detection and particle identification with avalanche photodiodes

    SciTech Connect

    Diepold, Marc Franke, Beatrice; Götzfried, Johannes; Hänsch, Theodor W.; Krauth, Julian J.; Mulhauser, Françoise; Nebel, Tobias; Pohl, Randolf; Fernandes, Luis M. P.; Amaro, Fernando D.; Gouvea, Andrea L.; Monteiro, Cristina M. B.; Santos, Joaquim M. F. dos; Machado, Jorge; Amaro, Pedro; Santos, José Paulo; and others

    2015-05-15

    Avalanche photodiodes are commonly used as detectors for low energy x-rays. In this work, we report on a fitting technique used to account for different detector responses resulting from photoabsorption in the various avalanche photodiode layers. The use of this technique results in an improvement of the energy resolution at 8.2 keV by up to a factor of 2 and corrects the timing information by up to 25 ns to account for space dependent electron drift time. In addition, this waveform analysis is used for particle identification, e.g., to distinguish between x-rays and MeV electrons in our experiment.

  18. Silicon photodiode with selective Zr/Si coating for extreme ultraviolet spectral range

    SciTech Connect

    Aruev, P N; Barysheva, Mariya M; Ber, B Ya; Zabrodskaya, N V; Zabrodskii, V V; Lopatin, A Ya; Pestov, Alexey E; Petrenko, M V; Polkovnikov, V N; Salashchenko, Nikolai N; Sukhanov, V L; Chkhalo, Nikolai I

    2012-10-31

    The procedure of manufacturing silicon photodiodes with an integrated Zr/Si filter for extreme ultraviolet (EUV) spectral range is developed. A setup for measuring the sensitivity profile of detectors with spatial resolution better than 100 {mu}m is fabricated. The optical properties of silicon photodiodes in the EUV and visible spectral ranges are investigated. Some characteristics of SPD-100UV diodes with Zr/Si coating and without it, as well as of AXUV-100 diodes, are compared. In all types of detectors a narrow region beyond the operating aperture is found to be sensitive to the visible light. (photodetectors)

  19. Injection photodiodes based on low-resistivity ZnS single crystals

    SciTech Connect

    Losev, V. V.

    2009-12-15

    Results of an experimental study of Ni-n-n{sup +}-In photodiode structures fabricated from a low-resistivity ZnS:Al crystal (n{sup +}-region) are reported. The high-resistivity compensated n-type layer is produced by thermal diffusion of silver. The photodiodes exhibit an injection amplification of the photocurrent under a forward bias of 1-10 V. The dependence of the currents through the diodes on the thickness of the n-type layer in the dark and under UV irradiation is determined. The photosensitivity is at a maximum in the fundamental absorption range in a narrow spectral band.

  20. A near infrared organic photodiode with gain at low bias voltage

    SciTech Connect

    Campbell, Ian H; Crone, Brian K

    2009-01-01

    We demonstrate an organic photodiode with near infrared optical response out to about 1100 run with a gain of {approx}10 at 1000 run under 5V reverse bias. The diodes employ a soluble naphthalocyanine with a peak absorption coefficient of {approx}10{sup 5} cm{sup -1} at 1000 nm. In contrast to most organic photodiodes, no exciton dissociating material is used. At zero bias, the diodes are inefficient with an external quantum efficiency of {approx} 10{sup -2}. In reverse bias, large gain occurs and is linear with bias voltage above 4V. The observed gain is consistent with a photoconductive gain mechanism.

  1. Hybrid photodetector for single-molecule spectroscopy and microscopy

    PubMed Central

    Michalet, X.; Cheng, Adrian; Antelman, Joshua; Suyama, Motohiro; Arisaka, Katsushi; Weiss, Shimon

    2011-01-01

    We report benchmark tests of a new single-photon counting detector based on a GaAsP photocathode and an electron-bombarded avalanche photodiode developed by Hamamatsu Photonics. We compare its performance with those of standard Geiger-mode avalanche photodiodes. We show its advantages for FCS due to the absence of after-pulsing and for fluorescence lifetime measurements due to its excellent time resolution. Its large sensitive area also greatly simplifies setup alignment. Its spectral sensitivity being similar to that of recently introduced CMOS SPADs, this new detector could become a valuable tool for single-molecule fluorescence measurements, as well as for many other applications. PMID:21822361

  2. HgCdTe MWIR Back-Illuminated Electron-Initiated Avalanche Photodiode Arrays

    NASA Astrophysics Data System (ADS)

    Reine, M. B.; Marciniec, J. W.; Wong, K. K.; Parodos, T.; Mullarkey, J. D.; Lamarre, P. A.; Tobin, S. P.; Gustavsen, K. A.; Williams, G. M.

    2007-08-01

    This paper reports data for back-illuminated planar n-on-p HgCdTe electron-initiated avalanche photodiode (e-APD) 4 × 4 arrays with large unit cells (250 × 250 μm2). The arrays were fabricated from p-type HgCdTe films grown by liquid phase epitaxy (LPE) on CdZnTe substrates. The arrays were bump-mounted to fanout boards and characterized in the back-illuminated mode. Gain increased exponentially with reverse bias voltage, and the gain versus bias curves were quite uniform from element to element. The maximum gain measured was 648 at -11.7 V for a cutoff wavelength of 4.06 μm at 160 K. For the same reverse-bias voltage, the gains measured at 160 K for elements with two different cutoff wavelengths (3.54 μm and 4.06 μm at 160 K) show an exponential increase with increasing cutoff wavelength, in agreement with Beck’s empirical model for gain versus voltage and cutoff wavelength in HgCdTe e-APDs. Spot scan data show that both the V = 0 response and the gain at V = -5.0 V are spatially uniform over the large junction area. To the best of our knowledge, these are the first spot scan data for avalanche gain ever reported for HgCdTe e-APDs. Capacitance versus voltage data are consistent with an ideal abrupt junction having a donor concentration equal to the indium concentration in the LPE film.

  3. The blocking probability of Geiger-mode avalanche photo-diodes

    NASA Technical Reports Server (NTRS)

    Moision, Bruce; Srinivasan, Meera; Hamkins, Jon

    2005-01-01

    When a photo is detected by a Geiger-mode avalanche photo-diode (GMAPD), the detector is rendered inactive, or blocked, for a certain period of time. In this paper we derive the blocking probability for a GMAPD whose input is either an unmodulated, Benoulli modulated or pulse-position-modulated Poisson process.

  4. Photon Detection with Cooled Avalanche Photodiodes: Theory and Preliminary Experimental Results

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Hays, D. A.

    1985-01-01

    Avalanche photodiodes (APDs) can be operated in a geiger-tube mode so that they can respond to single electron events and thus be used as photon counting detectors. Operational characteristics and theory of APDs while used in this mode are analyzed and assessed. Preliminary experimental investigation of several commercially available APDs has commenced, and initial results for dark count statistics are presented.

  5. Photoionization of Trapped Carriers in Avalanche Photodiodes to Reduce Afterpulsing During Geiger-Mode Photon Counting

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.

    2005-01-01

    We reduced the afterpulsing probability by a factor of five in a Geiger-mode photon-counting InGaAs avalanche photodiode by using sub-band-gap (lambda = 1.95 micron) laser diode illumination, which we believe photoionizes the trapped carriers.

  6. Scintillation light read-out by thin photodiodes in silicon wells

    NASA Astrophysics Data System (ADS)

    Allier, C. P.; Hollander, R. W.; Sarro, P. M.; van Eijk, C. W. E.

    2000-03-01

    Several applications of X-ray and gamma ray imaging detectors, e.g. in medical diagnostics, require millimeter or sub-millimeter spatial resolution and good energy resolution. In order to achieve such features we have proposed a new type of camera, which takes advantage of micromachining technology. It consists of an array of scintillator crystals encapsulated in silicon wells with photodiodes at the bottom. Several parameters of the photodiode need to be optimised: uniformity and efficiency of the light detection, gain, electronic noise and breakdown voltage. In order to evaluate these parameters we have processed 3×3 arrays of 1.8 mm2, ˜10 μm thick photodiodes using (1 0 0) wafers etched in a KOH solution. Their optical response at 675 nm wavelength is comparable to that of a 500 μm thick silicon PIN diode. Their low light detection efficiency is compensated by internal amplification. Several scintillator materials have been positioned in the wells on top of the thin photodiodes, i.e. a 200 μm thick film of structured CsI(Tl), single crystals of CsI(Tl) and Lu2S3(Ce3+). First experiments of γ-ray detection have been performed.

  7. Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits

    PubMed Central

    Aull, Brian

    2016-01-01

    This article reviews MIT Lincoln Laboratory's work over the past 20 years to develop photon-sensitive image sensors based on arrays of silicon Geiger-mode avalanche photodiodes. Integration of these detectors to all-digital CMOS readout circuits enable exquisitely sensitive solid-state imagers for lidar, wavefront sensing, and passive imaging. PMID:27070609

  8. AlInAsSb separate absorption, charge, and multiplication avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Ren, Min; Maddox, Scott J.; Woodson, Madison E.; Chen, Yaojia; Bank, Seth R.; Campbell, Joe C.

    2016-05-01

    We report AlxIn1-xAsySb1-y separate absorption, charge, and multiplication avalanche photodiodes (APDs) that operate in the short-wavelength infrared spectrum. They exhibit excess noise factor less or equal to that of Si and the low dark currents typical of III-V compound APDs.

  9. Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits.

    PubMed

    Aull, Brian

    2016-01-01

    This article reviews MIT Lincoln Laboratory's work over the past 20 years to develop photon-sensitive image sensors based on arrays of silicon Geiger-mode avalanche photodiodes. Integration of these detectors to all-digital CMOS readout circuits enable exquisitely sensitive solid-state imagers for lidar, wavefront sensing, and passive imaging. PMID:27070609

  10. A new circuit model of HgCdTe photodiode for SPICE simulation of integrated IRFPA

    NASA Astrophysics Data System (ADS)

    Saxena, Raghvendra Sahai; Saini, Navneet Kaur; Bhan, R. K.; Sharma, R. K.

    2014-11-01

    We propose a novel sub circuit model to simulate HgCdTe infrared photodiodes in a circuit simulator, like PSPICE. We have used two diodes of opposite polarity in parallel to represent the forward biased and the reverse biased behavior of an HgCdTe photodiode separately. We also connected a resistor in parallel with them to represent the ohmic shunt and a constant current source to represent photocurrent. We show that by adjusting the parameters in standard diode models and the resistor and current values, we could actually fit the measured data of our various HgCdTe photodiodes having different characteristics. This is a very efficient model that can be used for simulation of readout integrated circuit (ROIC) for HgCdTe IR photodiode arrays. This model also allows circuit level Monte Carlo simulation on a complete IRFPA at a single circuit simulator platform to estimate the non-uniformity for given processes of HgCdTe device fabrication and Si ROIC fabrication.

  11. Balanced InGaAs/InP avalanche photodiodes for single photon detection

    NASA Astrophysics Data System (ADS)

    Lu, Zhiwen; Sun, Wenlu; Zheng, Xiaoguang; Campbell, Joe; Jiang, Xudong; Itzler, Mark A.

    2012-10-01

    Abstract - We demonstrate a sinusoidally-gated InGaAs/InP photodiode pair operated at wavelength of 1310 nm with high photon detection efficiency (PDE) and low dark count rate (DCR). The photodiode pair is biased in a balanced scenario so that the common component of the output signal is cancelled. The concept of balanced photodiodes helps improve detection efficiency while canceling the common mode signal, which, in this case, is the capacitive response of the photodiodes. In conventional sinusoidal gating, an extra component, - an RF filter (or several) at the gating frequency, is utilized to filter out the gating signal and leave the avalanche signal for detection. For this configuration, sinusoidally-gated counting systems are restricted to a single frequency. With the balanced single photon diodes (SPAD), sinusoidal gating within a continuous frequency range is feasible. A printed circuit with symmetric layout of two bias tees was fabricated on a duroid board to enable the application of AC and DC signals for the dual SPADs. At a laser repletion rate of 1 MHz and temperature of 240 K the DCR and PDE were 58 kHz and 43%, respectively. Afterpulsing probability was lower compared with a sinusoidually-gated single SPAD. Jitter of 240 ps was achieved with 1 photon per pulse for an excess bias of 1.6%.

  12. Experimental analysis of a novel and low-cost pin photodiode dosimetry system for diagnostic radiology

    NASA Astrophysics Data System (ADS)

    Nazififard, Mohammad; Suh, Kune Y.; Mahmoudieh, Afshin

    2016-07-01

    Silicon PIN photodiode has recently found broad and exciting applications in the ionizing radiation dosimetry. In this study a compact and novel dosimetry system using a commercially available PIN photodiode (BPW34) has been experimentally tested for diagnostic radiology. The system was evaluated with clinical beams routinely used for diagnostic radiology and calibrated using a secondary reference standard. Measured dose with PIN photodiode (Air Kerma) varied from 10 to 430 μGy for tube voltages from 40 to 100 kVp and tube current from 0.4 to 40 mAs. The minimum detectable organ dose was estimated to be 10 μGy with 20% uncertainty. Results showed a linear correlation between the PIN photodiode readout and dose measured with standard dosimeters spanning doses received. The present dosimetry system having advantages of suitable sensitivity with immediate readout of dose values, low cost, and portability could be used as an alternative to passive dosimetry system such as thermoluminescent dosimeter for dose measurements in diagnostic radiology.

  13. Fabrication and performance of intrinsic germanium photodiodes. [for atmospheric IR spectroscopy

    NASA Technical Reports Server (NTRS)

    Beiting, E. J., III; Feldman, P. D.

    1977-01-01

    The paper presents fabrication details for an intrinsic germanium photodiode developed for study of atmospheric constituents, the airglow and auroras in the 1-2 micron spectral range. Attention is given to cutting of the single crystal, spreading of the lithium dispersion, sputtering of a gold coating, and surface passivation. A wavelength response curve is presented.

  14. Passivation of MBE grown InGaSb/InAs superlattice photodiodes

    NASA Technical Reports Server (NTRS)

    Hill, Cory J.; Keo, Sam S.; Mumolo, Jason M.; Gunapala, Sarath D.

    2005-01-01

    We have performed wet chemical passivation tests on InGaSb/InAs superlattice photodiode structures grown molecular beam epitaxy. The details of the devices growth and characterization as well as the results of chemical passivation involving RuCl3 and H2SO4 with SiO2 dielectric depositions are presented.

  15. Nano- and micro-structured silicon for hybrid near-infrared photodetectors

    NASA Astrophysics Data System (ADS)

    Äńerek, V.; Głowacki, E. D.; Bednorz, M.; Demchyshyn, S.; Sariciftci, N. S.; Ivanda, M.

    2016-05-01

    Structuring surface and bulk of crystalline silicon on different length scales can significantly alter its properties and possibly improve the performance of opto-electronic devices and sensors based on silicon. Different dominant feature scales are responsible for modification of some of electronic and optical properties of silicon. Several easily reproducible chemical methods for facile structuring of silicon on nano and micro-scales, based on both electroless and anodic etching of silicon in hydrofluoric acid based etchants, and chemical anisotropic etching of silicon in basic environments, are presented. We show how successive micro and nano structuring creates hierarchical silicon surfaces, which can be used to simultaneously exploit the advantages of both structuring feature length scales. Finally, we demonstrate a large increase in photocurrent obtained from a hybrid structured silicon/organic near-infrared photodetector. Improved silicon/6,6'-dibromoindigo hybrid photodiodes were prepared by nano- and micro-structuring the silicon part of the heterojunction by wet chemical etching methods. Photocurrent and spectral responsivity were improved in comparison to planar diodes by up to two orders of magnitude by optimization of the silicon structuring process. We show that the improvement in photocurrent is not due to the increase in surface area or light trapping.

  16. Low phase noise high power handling InGaAs photodiodes for precise timing applications

    NASA Astrophysics Data System (ADS)

    Datta, Shubhashish; Joshi, Abhay; Becker, Don

    2009-05-01

    Time is the most precisely measured physical quantity. Such precision is achieved by optically probing hyperfine atomic transitions. These high Q-factor resonances demonstrate frequency instability of ~10-18 over 1 s observation time. Conversion of such a stable optical clock signal to an electrical clock through photodetection introduces additional phase noise, thereby resulting in a significant degradation in the frequency stability. This excess phase noise is primarily caused by the conversion of optical intensity noise into electrical phase noise by the phase non-linearity of the photodetector, characterized by its power-to-phase conversion factor. It is necessary to minimize this phase nonlinearity in order to develop the next generation of ultra-high precision electronic clocks. Reduction in excess phase noise must be achieved while ensuring a large output RF signal generated by the photodetector. The phase linearity in traditional system designs that employ a photoreceiver, namely a photodiode followed by a microwave amplifier, is limited by the phase non-linearity of the amplifier. Utilizing high-power handling photodiodes eliminates the need of microwave amplifiers. In this work, we present InGaAs p-i-n photodiodes that display a power-to-phase conversion factor <6 rad/W at a peak-to-peak RF output amplitude of 2 V. In comparison, the photodiode coupled to a transimpedance amplifier demonstrates >44 rad/W at a peak-to-peak RF output amplitude of 0.5 V. These results are supported by impulse response measurements at 1550 nm wavelength at 1 GHz repetition rate. These photodiodes are suitable of applications such as optical clock distribution networks, photonic analog-to-digital converters, and phased array radars.

  17. An InP/Si heterojunction photodiode fabricated by self-aligned corrugated epitaxial lateral overgrowth

    SciTech Connect

    Sun, Y. T. Omanakuttan, G.; Lourdudoss, S.

    2015-05-25

    An n-InP/p-Si heterojunction photodiode fabricated by corrugated epitaxial lateral overgrowth (CELOG) method is presented. N-InP/p-Si heterojunction has been achieved from a suitable pattern containing circular shaped openings in a triangular lattice on the InP seed layer on p-Si substrate and subsequent CELOG of completely coalesced n-InP. To avoid current path through the seed layer in the final photodiode, semi-insulating InP:Fe was grown with adequate thickness prior to n-InP growth in a low pressure hydride vapor phase epitaxy reactor. The n-InP/p-Si heterointerface was analyzed by scanning electron microscopy and Raman spectroscopy. Room temperature cross-sectional photoluminescence (PL) mapping illustrates the defect reduction effect in InP grown on Si by CELOG method. The InP PL intensity measured above the InP/Si heterojunction is comparable to that of InP grown on a native planar substrate indicating low interface defect density of CELOG InP despite of 8% lattice mismatch with Si. The processed n-InP/p-Si heterojunction photodiodes show diode characteristics from the current-voltage (I-V) measurements with a dark current density of 0.324 mA/cm{sup 2} at a reverse voltage of −1 V. Under the illumination of AM1.5 conditions, the InP/Si heterojunction photodiode exhibited photovoltaic effect with an open circuit voltage of 180 mV, a short circuit current density of 1.89 mA/cm{sup 2}, an external quantum efficiency of 4.3%, and an internal quantum efficiency of 6.4%. This demonstration of epitaxially grown InP/Si heterojunction photodiode will open the door for low cost and high efficiency solar cells and photonic integration of III-Vs on silicon.

  18. Video-speed detection of the absolute position of a light point on a large-area photodetector based on luminescent waveguides.

    PubMed

    Koeppe, Robert; Neulinger, Anton; Bartu, Petr; Bauer, S

    2010-02-01

    A large-area photosensor is presented that uses the coupling of light into the planar waveguide mode of a polycarbonate foil by luminescent dyes to extend the active area of silicon photodiodes attached to the surface of the foil in a regular pattern. The photodiode signal is directly related to the distance between the point where light is coupled into the foil and the photodiode, thus enabling a precise recovery of the position of a localized light signal hitting the foil. We present a large-area device that can trace the movement of a light point generated by a laser pointer hitting its surface. PMID:20174049

  19. Performance of a PET detector module utilizing an array of silicon photodiodes to identify the crystal of interaction

    SciTech Connect

    Moses, W.W.; Derenzo, S.E. ); Nutt, R.; Digby, W.M.; Williams, C.W.; Andreaco, M. )

    1992-11-01

    We present initial performance results for a new multi-layer PET detector module consisting of an array of 3 mm square by 30 mm deep BGO crystals coupled on one end to a single photomultiplier tube and on the opposite end to an array of 3 mm square silicon photodiodes. The photomultiplier tube provides an accurate timing pulse and energy discrimination for the all the crystals in the module, while the silicon photodiodes identify the crystal of interaction. When a single BGO crystal at +25[degree]C is excited with 511 key photons, we measure a photodiode signal centered at 700 electrons (e[sup [minus

  20. Modal Bin Hybrid Model: A Surface Area Consistent, Triple Moment Sectional Method for Use in Process-oriented Modeling of Atmospheric Aerosols

    SciTech Connect

    Kajino, Mizuo; Easter, Richard C.; Ghan, Steven J.

    2013-09-10

    A triple moment sectional method, Modal Bin Hybrid Model (MBHM), has been developed. In addition to number and mass (volume), surface area is predicted (and preserved), which is important for gas-to-particle mass transfer and light extinction cross section. The performance of MBHM was evaluated against double moment sectional (DMS) methods with various size resolutions up to BIN256 (BINx: x is number of sections over three orders of magnitude in size, ΔlogD = 3/x) for simulating evolution of particles under simultaneously occurring nucleation, condensation and coagulation processes. Because MBHM gives a physically consistent form of the intra-sectional distributions, errors and biases of MBHM at BIN4-8 resolution were almost equivalent to those of DMS at BIN16-32 resolution for various important variables such as the moments Mk (k: 0, 2, 3), dMk/dt, and the number and volume of particles larger than a certain diameter. Another important feature of MBHM is that only a single bin is adequate to simulate full aerosol dynamics for particles whose size distribution can be approximated by a single lognormal mode. This flexibility is useful for process-oriented (multi category and/or mixing state) modeling: primary aerosols whose size parameters would not differ substantially in time and space can be expressed by a single or a small number of modes, whereas secondary aerosols whose size changes drastically from one to several hundred nanometers can be expressed by a number of modes. Added dimensions can be applied to MBHM to represent mixing state or photo-chemical age for aerosol mixing state studies.

  1. Studies of Avalanche Photodiodes (APDS) as Readout Devices for Scintillating Fibers for High Energy Gamma-Ray Astronomy Telescopes

    NASA Technical Reports Server (NTRS)

    Vasile, Stefan; Shera, Suzanne; Shamo, Denis

    1998-01-01

    New gamma ray and charged particle telescope designs based on scintillating fiber arrays could provide low cost, high resolution, lightweight, very large area and multi radiation length instrumentation for planned NASA space exploration. The scintillating fibers low visible light output requires readout sensors with single photon detection sensitivity and low noise. The sensitivity of silicon Avalanche Photodiodes (APDS) matches well the spectral output of the scintillating fibers. Moreover, APDs have demonstrated single photon capability. The global aim of our work is to make available to NASA a novel optical detector concept to be used as scintillating fiber readouts and meeting the requirements of the new generations of space-borne gamma ray telescopes. We proposed to evaluate the feasibility of using RMD's small area APDs ((mu)APD) as scintillating fiber readouts and to study possible alternative (mu)APD array configurations for space borne readout scintillating fiber systems, requiring several hundred thousand to one million channels. The evaluation has been conducted in accordance with the task description and technical specifications detailed in the NASA solicitation "Studies of Avalanche Photodiodes (APD as readout devices for scintillating fibers for High Energy Gamma-Ray Astronomy Telescopes" (#8-W-7-ES-13672NAIS) posted on October 23, 1997. The feasibility study we propose builds on recent developments of silicon APD arrays and light concentrators advances at RMD, Inc. and on more than 5 years of expertise in scintillating fiber detectors. In a previous program we carried out the initial research to develop a high resolution, small pixel, solid-state, silicon APD array which exhibited very high sensitivity in the UV-VIS spectrum. This (mu)APD array is operated in Geiger mode and results in high gain (greater than 10(exp 8)), extremely low noise, single photon detection capability, low quiescent power (less than 10 (mu)W/pixel for 30 micrometers sensitive

  2. A CMOS image sensor with stacked photodiodes for lensless observation system of digital enzyme-linked immunosorbent assay

    NASA Astrophysics Data System (ADS)

    Takehara, Hironari; Miyazawa, Kazuya; Noda, Toshihiko; Sasagawa, Kiyotaka; Tokuda, Takashi; Kim, Soo Hyeon; Iino, Ryota; Noji, Hiroyuki; Ohta, Jun

    2014-01-01

    A CMOS image sensor with stacked photodiodes was fabricated using 0.18 µm mixed signal CMOS process technology. Two photodiodes were stacked at the same position of each pixel of the CMOS image sensor. The stacked photodiodes consist of shallow high-concentration N-type layer (N+), P-type well (PW), deep N-type well (DNW), and P-type substrate (P-sub). PW and P-sub were shorted to ground. By monitoring the voltage of N+ and DNW individually, we can observe two monochromatic colors simultaneously without using any color filters. The CMOS image sensor is suitable for fluorescence imaging, especially contact imaging such as a lensless observation system of digital enzyme-linked immunosorbent assay (ELISA). Since the fluorescence increases with time in digital ELISA, it is possible to observe fluorescence accurately by calculating the difference from the initial relation between the pixel values for both photodiodes.

  3. Modeling of high-precision wavefront sensing with new generation of CMT avalanche photodiode infrared detectors.

    PubMed

    Gousset, Silvère; Petit, Cyril; Michau, Vincent; Fusco, Thierry; Robert, Clelia

    2015-12-01

    Near-infrared wavefront sensing allows for the enhancement of sky coverage with adaptive optics. The recently developed HgCdTe avalanche photodiode arrays are promising due to their very low detector noise, but still present an imperfect cosmetic that may directly impact real-time wavefront measurements for adaptive optics and thus degrade performance in astronomical applications. We propose here a model of a Shack-Hartmann wavefront measurement in the presence of residual fixed pattern noise and defective pixels. To adjust our models, a fine characterization of such an HgCdTe array, the RAPID sensor, is proposed. The impact of the cosmetic defects on the Shack-Hartmann measurement is assessed through numerical simulations. This study provides both a new insight on the applicability of cadmium mercury telluride (CMT) avalanche photodiodes detectors for astronomical applications and criteria to specify the cosmetic qualities of future arrays. PMID:26836674

  4. A low-noise large dynamic-range readout suitable for laser spectroscopy with photodiodes

    NASA Astrophysics Data System (ADS)

    Pullia, A.; Sanvito, T.; Potenza, M. A.; Zocca, F.

    2012-10-01

    An original low-noise large dynamic-range readout system for optical light spectroscopy with PIN diodes is presented. The front-end circuit is equipped with a smart device for automatic cancellation of the large dc offset brought about by the photodiode current. This device sinks away the exact amount of dc current from the preamplifier input, yielding auto zeroing of the output-voltage offset, while introducing the minimum electronic noise possible. As a result the measurement dynamic-range is maximized. Moreover, an auxiliary inspection point is provided which precisely tracks the dc component of the photodiode current. This output allows for precise beam alignment and may also be used for diagnostic purposes. The excellent gain stability and linearity make the circuit perfectly suited for optical-light pulse spectroscopy. Applications include particle sizing in the 100 nm range, two-dimensional characterization of semiconductor detectors, ultra-precise characterization of laser beam stability, confocal microscopy.

  5. Air-bridge high-speed InGaAs/InP waveguide photodiode

    NASA Astrophysics Data System (ADS)

    Yang, H.; Daunt, C. L. L. M.; Han, W.; Thomas, K.; Corbett, B.; Peters, F. H.

    2012-04-01

    The photodiode (PD) is a key component in optical transmission and optical measurement systems which receive optical signals and convert them into electric signals. High speed, high responsivity, high power and low dark current are desirable attributes of the PD in these applications, but also a simple fabrication process for high yield and low cost is essential for industry production. In this paper, an undercut-air-bridge high speed InGaAs/InP PIN structural photodiode is presented. By utilizing the crystal orientation dependent wet etching of InP material and designing the arms of the bridge with proper angle, the air bridge was easily obtained, which greatly eased the fabrication. The fabricated devices with 120μm×3μm ridge waveguides work robustly up to 30GHz in the measurements and potentially faster with optimized material.

  6. Dynamics of local micro-breakdown in the Geiger mode of avalanche photodiodes

    SciTech Connect

    Verhovtseva, A. V. Gergel, V. A.

    2009-07-15

    Mathematical modeling methods were used to study the dynamics of micro-breakdown development in structures of silicon avalanche photodiodes. The constructed model considers the locality of the avalanchexs multiplication region appearing during single photon absorption and the delay of the avalanchexs current spreading over the rear electrode of the diode. The calculations showed two different phases of transient process of the formation of the electrical signal, i.e., the rapid and slow ones due to current spreading and ordinary RC recharge, respectively. The load resistances required to implement the pulsed mode of operation of the structures of the avalanche photodiode were calculated for a series of actual diode capacitances and spreading resistances of the rear electrode.

  7. Application of a silicon photodiode array for solar edge tracking in the Halogen Occultation Experiment

    NASA Technical Reports Server (NTRS)

    Mauldin, L. E., III; Moore, A. S.; Stump, C. S.; Mayo, L. S.

    1985-01-01

    The optical and electronic design of the Halogen Occultation Experiment (HALOE) elevation sunsensor is described. This system uses a Galilean telescope to form a solar image on a linear silicon photodiode array. The array is a self-scanned, monolithic charge coupled device. The addresses of both solar edges imaged on the array are used by the control/pointing system to scan the HALOE science instantaneous-field-of-view (IFOV) across the vertical solar diameter during instrument calibration, and then maintain the science IFOV four arcmin below the top edge during the science data occultation event. Vertical resolution of 16 arcsec and a radiometric dynamic range of 100 are achieved at the 0.7 micrometer operating wavelength. The design provides for loss of individual photodiode elements without loss of angular tracking capability. The HALOE instrument is a gas correlation radiometer that is now being developed by NASA Langley Research Center for the Upper Atmospheric Research Satellite.

  8. A new analytical compact model for two-dimensional finger photodiodes

    NASA Astrophysics Data System (ADS)

    Naeve, T.; Hohenbild, M.; Seegebrecht, P.

    2008-02-01

    A new physically based circuit simulation model for finger photodiodes has been proposed. The approach is based on the solution of transport and continuity equation for generated carriers within the two-dimensional structure. As an example we present results of a diode consisting of N+-fingers located in a P-well on top of a N-type buried layer integrated in a P-type silicon substrate (N+/PW/NBL/Psub finger photodiode). The model is capable to predict the sensitivity of the diode in a wide spectral range very accurately. The structure under consideration was fabricated in an industrial 0.6 μm BiCMOS process. The good agreement of simulated sensitivity data with results of measurements and numerical simulations demonstrate the high quality of our model.

  9. One- and two-photon photocurrents from tunable organic microcavity photodiodes

    NASA Astrophysics Data System (ADS)

    Koeppe, R.; Müller, J. G.; Lupton, J. M.; Feldmann, J.; Scherf, U.; Lemmer, U.

    2003-04-01

    We have constructed multilayer thin-film organic microcavity photodiodes with the photoactive layer comprised of a spin-coated conjugated polymer and an evaporated C60 layer. The electrodes are designed as semitransparent mirrors which form a resonant cavity structure. The photocurrent spectra show distinct maxima at the optical resonances of the cavities, which are located up to 200 nm below the fundamental optical transition of the polymer. The design allows a simple tuning of the spectral response by varying the layer thickness. Microcavity photodiodes are also shown to be highly sensitive two-photon detectors, which exhibit a factor 500 improvement in the two-photon response compared to devices without photonic confinement.

  10. A low cost X-ray imaging device based on BPW-34 Si-PIN photodiode

    NASA Astrophysics Data System (ADS)

    Emirhan, E.; Bayrak, A.; Yücel, E. Barlas; Yücel, M.; Ozben, C. S.

    2016-05-01

    A low cost X-ray imaging device based on BPW-34 silicon PIN photodiode was designed and produced. X-rays were produced from a CEI OX/70-P dental tube using a custom made ±30 kV power supply. A charge sensitive preamplifier and a shaping amplifier were built for the amplification of small signals produced by photons in the depletion layer of Si-PIN photodiode. A two dimensional position control unit was used for moving the detector in small steps to measure the intensity of X-rays absorbed in the object to be imaged. An Aessent AES220B FPGA module was used for transferring the image data to a computer via USB. Images of various samples were obtained with acceptable image quality despite of the low cost of the device.

  11. LWIR HgCdTe barrier photodiode with Auger-suppression

    NASA Astrophysics Data System (ADS)

    Kopytko, M.; Kębłowski, A.; Gawron, W.; Pusz, W.

    2016-03-01

    This paper reports on advanced metalorganic chemical vapor deposition (MOCVD) grown HgCdTe barrier photodiodes for long wave infrared (LWIR) application. The n+p+Bp πN+ device is a concept of a specific barrier bandgap architecture integrated with Auger-suppression as a good solution for high operating temperature (HOT) infrared detectors with high detectivity and sub-nanosecond time constant. The design approach, growth aspects and detector characterization of HgCdTe n+p+Bp πN+ barrier photodiodes operated with thermoelectric cooling (230 K) have been discussed in the paper. The influence of absorber thickness on the device’s properties has been analyzed in the experiment.

  12. A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

    NASA Technical Reports Server (NTRS)

    Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

    1982-01-01

    A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location.

  13. Low-noise extended-frequency response with cooled silicon photodiodes

    NASA Technical Reports Server (NTRS)

    Neiswander, R. S.; Plews, G. S.

    1975-01-01

    It is shown that a substantial reduction in internal noise generated by the photodiode and the preamplifier can be produced by a modest cooling of the components and by optimization of preamplifier design. With this reduction the silicon detectors can, in the SNR range of 5 or greater, produce better performance than photon-noise-limited photomultipliers. The circuit noise and frequency response model suggested by Goranson and Skipper (1974) is expanded to include the effects of frequency dependent FET voltage noise and FET load resistance noise. The modeling of the photodiode and preamplifier is described and the noise characteristics of a 0.01 Hz to 100 kHz bandwidth detector/amplifier channel are evaluated.

  14. A3B5 photodiode sensors for low-temperature pyrometry

    NASA Astrophysics Data System (ADS)

    Sotnikova, Galina Y.; Aleksandrov, Sergey E.; Gavrilov, Gennadiy A.

    2011-05-01

    Mid-infrared immersion lens photodiodes developed at the Ioffe Institute have high spectral selectivity (λmax/▵λ~0.1...0.15) at different wavelengths -2.9, 3.3, 4.2 and 4.7 microns, the response time (up to 10-9s) and detectivity (D* ~ 109-1011, (cm√Hz)/W) being significantly higher than those of currently known detectors of thermal radiation[1].The analysis of the transfer function of the temperature sensors based on A3B5 photodiodes has shown that they permit implementing the methods of color and two-color pyrometry providing a significant decrease of the methodical error in optical temperature measurements associated with unknown values of object surface emissivity and uncontrollable changes in the environment transmission.

  15. A novel surface-enhanced Raman spectroscopy substrate based on a large area of MoS2 and Ag nanoparticles hybrid system

    NASA Astrophysics Data System (ADS)

    Chen, P. X.; Qiu, H. W.; Xu, S. C.; Liu, X. Y.; Li, Z.; Hu, L. T.; Li, C. H.; Guo, J.; Jiang, S. Z.; Huo, Y. Y.

    2016-07-01

    Few layers MoS2 were directly synthesized on Ag nanoparticles (AgNPs) by thermal decomposion method to fabricate a MoS2/AgNPs hybrid system for surface-enhanced Raman scattering (SERS). The MoS2/AgNPs hybrid system shows high performance in terms of sensitivity, signal-to-noise ratio, reproducibility and stability. The minimum detected concentration from MoS2/AgNPs hybrid system for R6 G can reach 10-9 M, which is one order of magnitude lower than that from AgNPs system. The hybrid system shows the reasonable linear response between the Raman intensity and concentration that R2 is reached to 0.988. The maximum deviations of SERS intensities from 20 positions of the SERS substrate are less than 13%. Besides, the hybrid system has a good stability, the Raman intensity only drop by 20% in a month. This work can provide a basis for the fabrication of novel SERS substrates.

  16. Silicon Geiger-mode avalanche photodiode arrays for photon-starved imaging

    NASA Astrophysics Data System (ADS)

    Aull, Brian F.

    2015-05-01

    Geiger-mode avalanche photodiodes (GMAPDs) are capable of detecting single photons. They can be operated to directly trigger all-digital circuits, so that detection events are digitally counted or time stamped in each pixel. An imager based on an array of GMAPDs therefore has zero readout noise, enabling quantum-limited sensitivity for photon-starved imaging applications. In this review, we discuss devices developed for 3D imaging, wavefront sensing, and passive imaging.

  17. Strain measurements using Fizzeau interferometry and photo-diode sensor in composite structures

    NASA Technical Reports Server (NTRS)

    Syed, Hazari I.; Balister, Raymond L.

    1990-01-01

    A system is presented which allows the measurement of very small changes of strain in real time and can be applied to the design of stable space structures. The Fizzeau interferometry technique is employed in conjunction with a tube dilatometer to generate a fringe pattern that expands and contracts with temperature variations. A photodiode array transforms the bulls eye fringes to video signals which can be analyzed to determine the strain in structural elements such as tubes.

  18. Extracting dark current components and characteristics parameters for InGaAs/InP avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Xu, Jiao; Chen, Xiaoshuang; Wang, Wenjuan; Lu, Wei

    2016-05-01

    The dark current of separate absorption grading charge multiplication (SAGCM) InGaAs/InP avalanche photodiodes has been numerical analyzed. SRH current, TAT current, BBT current and avalanche amplification combined together as the dark current have been extracted by simulation separately. The trend of punch-through voltage and breakdown voltage have been discussed, meanwhile the influence of structure parameters also has been investigated.

  19. Recent progress in high gain InAs avalanche photodiodes (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Bank, Seth; Maddox, Scott J.; Sun, Wenlu; Nair, Hari P.; Campbell, Joe C.

    2015-08-01

    InAs possesses nearly ideal material properties for the fabrication of near- and mid-infrared avalanche photodiodes (APDs), which result in strong electron-initiated impact ionization and negligible hole-initiated impact ionization [1]. Consequently, InAs multiplication regions exhibit several appealing characteristics, including extremely low excess noise factors and bandwidth independent of gain [2], [3]. These properties make InAs APDs attractive for a number of near- and mid-infrared sensing applications including remote gas sensing, light detection and ranging (LIDAR), and both active and passive imaging. Here, we discuss our recent advances in the growth and fabrication of high gain, low noise InAs APDs. Devices yielded room temperature multiplication gains >300, with much reduced (~10x) lower dark current densities. We will also discuss a likely key contributor to our current performance limitations: silicon diffusion into the intrinsic (multiplication) region from the underlying n-type layer during growth. Future work will focus on increasing the intrinsic region thickness, targeting gains >1000. This work was supported by the Army Research Office (W911NF-10-1-0391). [1] A. R. J. Marshall, C. H. Tan, M. J. Steer, and J. P. R. David, "Electron dominated impact ionization and avalanche gain characteristics in InAs photodiodes," Applied Physics Letters, vol. 93, p. 111107, 2008. [2] A. R. J. Marshall, A. Krysa, S. Zhang, A. S. Idris, S. Xie, J. P. R. David, and C. H. Tan, "High gain InAs avalanche photodiodes," in 6th EMRS DTC Technical Conference, Edinburgh, Scotland, UK, 2009. [3] S. J. Maddox, W. Sun, Z. Lu, H. P. Nair, J. C. Campbell, and S. R. Bank, "Enhanced low-noise gain from InAs avalanche photodiodes with reduced dark current and background doping," Applied Physics Letters, vol. 101, no. 15, pp. 151124-151124-3, Oct. 2012.

  20. Vacuum photodiode detectors for soft x-ray ITER plasma tomography

    NASA Astrophysics Data System (ADS)

    Gott, Yu. V.; Stepanenko, M. M.

    2005-07-01

    A special type of vacuum photodiode detector (VPD) for x-ray tomography of (ITER) plasma is described. Laboratory experiments demonstrate that VPD has high sensitivity to thermal x-rays and low sensitivity to hard gamma rays and neutrons. It was shown that in ITER environment the signal due to thermal x-rays will surpass the background signal by more than a factor of 100.

  1. Novel approach to improve reliable color recognition in a-Si:H photodiodes

    NASA Astrophysics Data System (ADS)

    Watty, Krystian; Bablich, Andreas; Seibel, Konstantin; Merfort, Christian; Böhm, Markus

    2012-06-01

    Optical detection is an often used technique for recognition of potentially dangerous materials. Hydrogenated amorphous silicon (a-Si:H) technology provides an inexpensive alternative material compared to crystalline silicon for being used in photonic devices operating in the visible spectrum. Further materials' key benefits are the high light absorption, the voltage-tunable spectral sensitivity and the high space efficiency. Present research efforts concentrate on the determination of the color information in a-Si:H photodiodes. This work presents an approach to improve color recognition of a-Si:H photodiodes by modifying the layer sequence. The maximum of the spectral response (SR) of a single i-layer a-Si:H photodiode can be shifted by varying its bias voltage. In this case, the shift is not more than some nanometers. Precise color recognition requires different SR maxima (e.g. RGB-model). One possibility to accomplish a separation of the SR is to engineer the bandgap; another idea, which is presented here, is based on a layer sequence modification. Normally, the SR at higher reverse bias voltages, with the maximum at longer wavelengths, encloses that at lower voltages. Splitting the SR leads to an improvement of color recognition and is achieved by depositing an additional interior anode. The SR maximum shift amounts to 100nm, from 570nm by contacting the interior anode, to 670nm at the top anode. Furthermore, the curves are clearly split. The presented approach should lead to a tunable multi-spectral photodiode for high quality color recognition. Such a diode can be used in photonic devices, e.g. for safety and security applications.

  2. Resonant cavity enhanced InGaAs photodiodes for high speed detection of 1.55 μm infrared radiation

    NASA Astrophysics Data System (ADS)

    Kaniewski, J.; Muszalski, J.; Pawluczyk, J.; Piotrowski, J.

    2005-05-01

    Resonant cavity enhanced photodetectors are promising candidates for applications in high-speed optical communications due to their high quantum efficiency and large bandwidth. This is a consequence of placing the thin absorber of the photodetector inside a Fabry-Perot microcavity so the absorption could be enhanced by recycling the photons with resonance wavelength. The performance of uncooled resonant cavity enhanced InGaAs/InAlAs photovoltaic devices operating near 1.55 μm has been studied both theoretically and experimentally. The analyses include two different types of structures with cavity end mirrors made of semiconducting and metallic reflectors as well as semiconducting and hybrid (dielectric Si3N4/SiO2 + metal) Bragg reflectors. Optimization of the device design includes: absorption layer thickness, position of absorption layer within the cavity and number of layers in distributed Bragg reflectors. Dependence of absorption on wavelength and incidence angle are discussed. Various issues related to applications of resonance cavity enhanced photodiodes in optical systems are considered. Practical devices with metallic and hybrid mirrors were fabricated by molecular beam epitaxy and by microwave-compatible processing. A properly designed device of this type has potential for subpicosecond response time.

  3. TCAD simulations of a novel UV and blue-extended photodiode

    NASA Astrophysics Data System (ADS)

    Chen, Chang-ping; Jin, Xiang-liang; Zhou, Xiao-ya; Yang, Hongjiao; Luo, Jun

    2013-08-01

    In this paper, a new UV and blue-extended photodiode with an octagon-ring-shaped structure is proposed, which have increased responsivity for the UV and blue light, high responsive speed with short rise and fall time and UV/blue selectivity. TCAD simulation approach is used to analyze the structural characteristics and photoelectric characteristics of this new photodiode. For the structural characteristics, doping profile, potential distribution and Electric field distribution are analyzed simply. For the photoelectric characteristics, the influences caused by doping concentration of n-well on dark current, avalanche breakdown voltage and transient response are discussed in detail. The finger distance (D) between two adjacent P+ anodes, the width (W) of P+ anode and the ratio of D/W are analyzed, witch affects the spectral response, DC characteristic and transient response obviously. The work of TCAD simulation in this paper is conducive to extract model parameters and process parameters of this new photodiode, which will further be used for numerical simulation to analyze its photoelectric characteristics, noise characteristics more accurately. This work is also a significant and helpful guide for device design and chip fabrication.

  4. Proton effects on low noise and high responsivity silicon-based photodiodes for space environment

    SciTech Connect

    Pedroza, Guillaume; Gilard, Olivier; Bourqui, Marie-Lise; Bechou, Laurent; Deshayes, Yannick; How, Lip Sun; Rosala, Francois

    2009-01-15

    A series of proton irradiations has been carried out on p-n silicon photodiodes for the purpose of assessing the suitability of these devices for the European Galileo space mission. The irradiations were performed at energies of 60, 100, and 150 MeV with proton fluences ranging from 1.7x10{sup 10} to 1x10{sup 11} protons/cm{sup 2}. Dark current, spectral responsivity, and dark current noise were measured before and after each irradiation step. We observed an increase in both dark current, dark current noise, and noise equivalent power and a drop of the spectral responsivity with increasing displacement damage dose. An analytical model has been developed to investigate proton damage effects through the modeling of the electro-optical characteristics of the photodiode. Experimental degradations were successfully explained taking into account the degradation of the minority carrier diffusion length in the N-region of the photodiode. The degradation model was then applied to assess the end-of-life performance of these devices in the framework of the Galileo mission.

  5. Slow-light effect in a silicon photonic crystal waveguide as a sub-bandgap photodiode.

    PubMed

    Terada, Yosuke; Miyasaka, Kenji; Ito, Hiroyuki; Baba, Toshihiko

    2016-01-15

    We demonstrate a Si sub-bandgap photodiode in a photonic crystal slow-light waveguide that operates at telecom wavelengths and can be fabricated using a Ge-free, standard Si-photonics CMOS process. In photodiodes based on absorption via mid-bandgap states, the slow-light enhancement enables performance that is well balanced among high responsivity, low dark current, high speed, wide working spectrum, and CMOS-process compatibility, all of which are otherwise difficult to achieve simultaneously. Owing to the slow-light effect and supplemental gain at a high reverse bias, the photodiode shows a responsivity of 0.15  A/W with a low dark current of 40 nA, which is attributed to no particular processes such as ion implantation and excess exposure of the Si surface. The maximum responsivity was 0.36  A/W. The modest gain allows for sufficient frequency bandwidth to observe an eye opening at up to 30  Gb/s. PMID:26766696

  6. Ceramic scintillator-coupled linear array PIN photodiode for X-ray scanner

    NASA Astrophysics Data System (ADS)

    Kim, Kwang Hyun; Kang, Dong-Wan; Cho, Gyuseong; Kim, Do Kyung

    2007-08-01

    In order to design the full system of dual-energy X-ray scanner, each component of the system has been fabricated and tested. The high-energy X-ray detector modules used a ceramic scintillator of Eu 3+-doped (Gd,Y) 2O 3, manufactured using Glycine Nitrate Process (GNP). This was coupled to a 16-channel linear array PIN-type photodiode. The low-energy module was a commercially available Lanex Regular screen that was also coupled to a 16-channel linear array PIN-type photodiode. The 16-channel linear array PIN-type photodiode of 1.5 mm×3.2 mm was fabricated in the process of Electronics and Telecommunications Research Institute (ETRI). With a data acquisition system, signal-to-noise ratio was measured at low X-ray energy and low photon flux to evaluate each scintillator-coupled detector module. Through the experiment results and analysis, we inspected each component of the system as a dual-energy single-exposure X-ray scanner.

  7. The use of hybrid fractures in paleostress determinations: test case with the the Palygorskite-bearing fractures in the Kinshasa area, DR Congo

    NASA Astrophysics Data System (ADS)

    Delvaux, Damien; Gloire, Ganza; Mees, Florias; Lahogue, Pascale

    2014-05-01

    Hybrid fractures represent the transition from extension fracture to shear fracture (Ramsey and Chester, 2004, Nature 428, 63-66). Although hybrid fractures have long been hypothesized to represent brittle fracture types between the extension and shear fractures end-members, it was only in 2004 that these authors succeeded to demonstrate their existence experimentally. As a consequence, observation of hybrid fractures in naturally deformed rocks remained ambiguous for a long time and only few studies reported their natural existence. Hybrid fractures have also not been considered so far as brittle element in paleostress reconstructions as their kinematic understanding was unclear. The Paleozoic Inkisi red sandstones of the West-Congo Supergroup in the region of Kinshasa and Brazzaville (Congo) are affected by prominent fracture sets, the most prominent of which are filled by palygorskite veins. They were formed in a strike-slip setting related to intraplate stress field generated by the mid Atlantic ridge push since that became efficient in late Cretaceous. We found an almost continuous range of fracture types, from plume joints to open fractures filled with calcite-palygorskite but without slip striae, and slickensided fractures with only thin films of redeposited palygorskite. The structural data have been analyzed with the Win-Tensor program (version 5.0.1) which has been adapted to consider hybrid fractures. Those are characterized by extension and shear, as opposed to tension fractures, on which no shear movement occurs, and to shear fractures, on which contraction occurs instead of extension. The results obtained suggest that the fractures have been initiated locally as plume joint and developed laterally under hybrid conditions. Later, some of them have been reactivated as strike-slip shear fractures and a new conjugated set appeared. Overall, this illustrates the progressive development with time of the stress state corresponding to an increase in the sigma

  8. From hybrid swarms to swarms of hybrids

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Szalanski, Allen L; Gaskin, John F.; Young, Nicholas E.; West, Amanda; Jarnevich, Catherine S.; Tripodi, Amber

    2015-01-01

    Science has shown that the introgression or hybridization of modern humans (Homo sapiens) with Neanderthals up to 40,000 YBP may have led to the swarm of modern humans on earth. However, there is little doubt that modern trade and transportation in support of the humans has continued to introduce additional species, genotypes, and hybrids to every country on the globe. We assessed the utility of species distributions modeling of genotypes to assess the risk of current and future invaders. We evaluated 93 locations of the genus Tamarix for which genetic data were available. Maxent models of habitat suitability showed that the hybrid, T. ramosissima x T. chinensis, was slightly greater than the parent taxa (AUCs > 0.83). General linear models of Africanized honey bees, a hybrid cross of Tanzanian Apis mellifera scutellata and a variety of European honey bee including A. m. ligustica, showed that the Africanized bees (AUC = 0.81) may be displacing European honey bees (AUC > 0.76) over large areas of the southwestern U.S. More important, Maxent modeling of sub-populations (A1 and A26 mitotypes based on mDNA) could be accurately modeled (AUC > 0.9), and they responded differently to environmental drivers. This suggests that rapid evolutionary change may be underway in the Africanized bees, allowing the bees to spread into new areas and extending their total range. Protecting native species and ecosystems may benefit from risk maps of harmful invasive species, hybrids, and genotypes.

  9. Monte Carlo simulations of compact gamma cameras based on avalanche photodiodes.

    PubMed

    Després, Philippe; Funk, Tobias; Shah, Kanai S; Hasegawa, Bruce H

    2007-06-01

    Avalanche photodiodes (APDs), and in particular position-sensitive avalanche photodiodes (PSAPDs), are an attractive alternative to photomultiplier tubes (PMTs) for reading out scintillators for PET and SPECT. These solid-state devices offer high gain and quantum efficiency, and can potentially lead to more compact and robust imaging systems with improved spatial and energy resolution. In order to evaluate this performance improvement, we have conducted Monte Carlo simulations of gamma cameras based on avalanche photodiodes. Specifically, we investigated the relative merit of discrete and PSAPDs in a simple continuous crystal gamma camera. The simulated camera was composed of either a 4 x 4 array of four channels 8 x 8 mm2 PSAPDs or an 8 x 8 array of 4 x 4 mm2 discrete APDs. These configurations, requiring 64 channels readout each, were used to read the scintillation light from a 6 mm thick continuous CsI:Tl crystal covering the entire 3.6 x 3.6 cm2 photodiode array. The simulations, conducted with GEANT4, accounted for the optical properties of the materials, the noise characteristics of the photodiodes and the nonlinear charge division in PSAPDs. The performance of the simulated camera was evaluated in terms of spatial resolution, energy resolution and spatial uniformity at 99mTc (140 keV) and 125I ( approximately 30 keV) energies. Intrinsic spatial resolutions of 1.0 and 0.9 mm were obtained for the APD- and PSAPD-based cameras respectively for 99mTc, and corresponding values of 1.2 and 1.3 mm FWHM for 125I. The simulations yielded maximal energy resolutions of 7% and 23% for 99mTc and 125I, respectively. PSAPDs also provided better spatial uniformity than APDs in the simple system studied. These results suggest that APDs constitute an attractive technology especially suitable to build compact, small field of view gamma cameras dedicated, for example, to small animal or organ imaging. PMID:17505089

  10. Progress in MBE grown type-II superlattice photodiodes

    NASA Technical Reports Server (NTRS)

    Hill, Cory J.; Li, Jian V.; Mumolo, Jason M.; Gunapala, Sarath D.

    2006-01-01

    We report on the status of GaSb/InAs type-II superlattice diodes grown and fabricated at the Jet Propulsion Laboratory designed for infrared absorption in the 8-12(mu)m range. Recent devices have produced detectivities as high as 8x10 to the tenth power Jones with a differential resistance-area product greater than 6 Ohmcm(sup 2) at 80K with a long wavelength cutoff of approximately 12(mu)m. The measured quantum efficiency of these front-side illuminated devices is close to 30% in the 10-11(mu)m range without antireflection coatings.

  11. Geiger-mode operation of ultraviolet avalanche photodiodes grown on sapphire and free-standing GaN substrates

    NASA Astrophysics Data System (ADS)

    Cicek, E.; Vashaei, Z.; McClintock, R.; Bayram, C.; Razeghi, M.

    2010-06-01

    GaN avalanche photodiodes (APDs) were grown on both conventional sapphire and low dislocation density free-standing (FS) c-plane GaN substrates. Leakage current, gain, and single photon detection efficiency (SPDE) of these APDs were compared. At a reverse-bias of 70 V, APDs grown on sapphire substrates exhibited a dark current density of 2.7×10-4 A/cm2 whereas APDs grown on FS-GaN substrates had a significantly lower dark current density of 2.1×10-6 A/cm2. Under linear-mode operation, APDs grown on FS-GaN achieved avalanche gain as high as 14 000. Geiger-mode operation conditions were studied for enhanced SPDE. Under front-illumination the 625-μm2-area APD yielded a SPDE of ˜13% when grown on sapphire substrates compared to more than 24% when grown on FS-GaN. The SPDE of the same APD on sapphire substrate increased to ˜30% under back-illumination—the FS-GaN APDs were only tested under front illumination due to the thick absorbing GaN substrate.

  12. Comparative study of various pixel photodiodes for digital radiography: Junction structure, corner shape and noble window opening

    NASA Astrophysics Data System (ADS)

    Kang, Dong-Uk; Cho, Minsik; Lee, Dae Hee; Yoo, Hyunjun; Kim, Myung Soo; Bae, Jun Hyung; Kim, Hyoungtaek; Kim, Jongyul; Kim, Hyunduk; Cho, Gyuseong

    2012-05-01

    Recently, large-size 3-transistors (3-Tr) active pixel complementary metal-oxide silicon (CMOS) image sensors have been being used for medium-size digital X-ray radiography, such as dental computed tomography (CT), mammography and nondestructive testing (NDT) for consumer products. We designed and fabricated 50 µm × 50 µm 3-Tr test pixels having a pixel photodiode with various structures and shapes by using the TSMC 0.25-m standard CMOS process to compare their optical characteristics. The pixel photodiode output was continuously sampled while a test pixel was continuously illuminated by using 550-nm light at a constant intensity. The measurement was repeated 300 times for each test pixel to obtain reliable results on the mean and the variance of the pixel output at each sampling time. The sampling rate was 50 kHz, and the reset period was 200 msec. To estimate the conversion gain, we used the mean-variance method. From the measured results, the n-well/p-substrate photodiode, among 3 photodiode structures available in a standard CMOS process, showed the best performance at a low illumination equivalent to the typical X-ray signal range. The quantum efficiencies of the n+/p-well, n-well/p-substrate, and n+/p-substrate photodiodes were 18.5%, 62.1%, and 51.5%, respectively. From a comparison of pixels with rounded and rectangular corners, we found that a rounded corner structure could reduce the dark current in large-size pixels. A pixel with four rounded corners showed a reduced dark current of about 200fA compared to a pixel with four rectangular corners in our pixel sample size. Photodiodes with round p-implant openings showed about 5% higher dark current, but about 34% higher sensitivities, than the conventional photodiodes.

  13. Visible light communication in dynamic environment using image/high-speed communication hybrid sensor

    NASA Astrophysics Data System (ADS)

    Maeno, Keita; Panahpour Tehrani, Mehrdad; Fujii, Toshiaki; Okada, Hiraku; Yamazato, Takaya; Tanimoto, Masayuki; Yendo, Tomohiro

    2012-01-01

    Visible Light Communication (VLC) is a wireless communication method using LEDs. LEDs can respond in high-speed and VLC uses this characteristics. In VLC researches, there are two types of receivers mainly, one is photodiode receiver and the other is high-speed camera. A photodiode receiver can communicate in high-speed and has high transmission rate because of its high-speed response. A high-speed camera can detect and track the transmitter easily because it is not necessary to move the camera. In this paper, we use a hybrid sensor designed for VLC which has advantages of both photodiode and high-speed camera, that is, high transmission rate and easy detecting of the transmitter. The light receiving section of the hybrid sensor consists of communication pixels and video pixels, which realizes the advantages. This hybrid sensor can communicate in static environment in previous research. However in dynamic environment, high-speed tracking of the transmitter is essential for communication. So, we realize the high-speed tracking of the transmitter by using the information of the communication pixels. Experimental results show the possibility of communication in dynamic environment.

  14. Flare Hybrids

    NASA Astrophysics Data System (ADS)

    Tomczak, M.; Dubieniecki, P.

    2015-12-01

    On the basis of the Solar Maximum Mission observations, Švestka ( Solar Phys. 121, 399, 1989) introduced a new class of flares, the so-called flare hybrids. When they start, they look like typical compact flares (phase 1), but later on, they look like flares with arcades of magnetic loops (phase 2). We summarize the characteristic features of flare hybrids in soft and hard X-rays as well as in the extreme ultraviolet; these features allow us to distinguish flare hybrids from other flares. In this article, additional energy release or long plasma cooling timescales are suggested as possible causes of phase 2. We estimate the frequency of flare hybrids, and study the magnetic configurations favorable for flare hybrid occurrence. Flare hybrids appear to be quite frequent, and the difference between the lengths of magnetic loops in the two interacting loop systems seem to be a crucial parameter for determining their characteristics.

  15. Effective amplifier noise for an optical receiver based on linear mode avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Chen, C.-C.

    1989-01-01

    The rms noise charge induced by the amplifier for an optical receiver based on the linear-mode avalanche photodiode (APD) was analyzed. It is shown that for an amplifier with a 1-pF capacitor and a noise temperature of 100 K, the rms noise charge due to the amplifier is about 300. Since the noise charge must be small compared to the signal gain, APD gains on the order of 1000 will be required to operate the receiver in the linear mode.

  16. Design and testing of an active quenching circuit for an avalanche photodiode photon detector

    NASA Technical Reports Server (NTRS)

    Arbel, D.; Schwartz, J. A.

    1991-01-01

    The photon-detection capabilities of avalanche photodiodes (APDs) operating above their theoretical breakdown voltages are described, with particular attention given to the needs and methods of quenching an avalanche once breakdown has occurred. A brief background on the motives of and previous work with this mode of operation is presented. Finally, a description of the design and testing of an active quenching circuit is given. Although the active quenching circuit did not perform as expected, knowledge was gained as to the signal amplitudes necessary for quenching and the need for a better model for the above-breakdown circuit characteristics of the Geiger-mode APD.

  17. Dark Current Degradation of Near Infrared Avalanche Photodiodes from Proton Irradiation

    NASA Technical Reports Server (NTRS)

    Becker, Heidi N.; Johnston, Allan H.

    2004-01-01

    InGaAs and Ge avalanche photodiodes (APDs) are examined for the effects of 63-MeV protons on dark current. Dark current increases were large and similar to prior results for silicon APDs, despite the smaller size of InGaAs and Ge devices. Bulk dark current increases from displacement damage in the depletion regions appeared to be the dominant contributor to overall dark current degradation. Differences in displacement damage factors are discussed as they relate to structural and material differences between devices.

  18. State-of-the-art performance of GaAlAs/GaAs avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Law, H. D.; Nakano, K.; Tomasetta, L. R.

    1979-01-01

    Ga(0.15)Al(0.85)As/GaAs avalanche photodiodes have been successfully fabricated. The performance of these detectors is characterized by a rise time of less than 35 ps, an external quantum efficiency with an antireflection coating of 95% at 0.53 microns, and a microwave optical gain of 42 dB. The dark current density is in the low range (10 to the minus A/sq cm) at one-half the breakdown voltages, and rises to 0.0001 A/sq cm at 42 dB optical gain.

  19. Illuminated to dark ratio improvement in lateral SOI PIN photodiodes at high temperatures

    NASA Astrophysics Data System (ADS)

    Novo, C.; Giacomini, R.; Doria, R.; Afzalian, A.; Flandre, D.

    2014-07-01

    This work presents a study of the illuminated to dark ratio (IDR) of lateral SOI PIN photodiodes. Measurements performed on fabricated devices show a fivefold improvement of the IDR when the devices are biased in accumulation mode and under high temperatures of operation, independently of the anode voltage. The obtained results show that the doping concentration of the intrinsic region has influence on the sensitivity of the diodes: the larger the doping concentration, the smaller the IDR. Furthermore, the photocurrent and dark current present lower values as the silicon film thickness is decreased, resulting in a further increase in the illuminated to dark ratio.

  20. [Study on UV-visible DOAS system based on photodiode array (PDA)].

    PubMed

    Qin, Min; Xie, Pin-hua; Liu, Jian-guo; Liu, Wen-qing; Fang, Wu; Lu, Fan; Li, Ang; Lu, Yi-huai; Wei, Qing-nong; Dou, Ke

    2005-09-01

    A long-path differential optical absorption spectroscopy (DOAS) system is introduced. A photodiode array is employed as the detector to replace the complicated SD detector which consists of a PMT and a slotted disk. The properties of the detector and the spectrometer unit such as offset, dark current, noise, linearity, resolution, and wavelength range were measured. This system was also tested to measure SO2 and NO2 in the atmosphere. The detection limits of this system for SO2, and NO2 over a 713 m light path were determined. PMID:16379291

  1. A prototype avalanche photodiode array for scintillating-fiber tracking detectors

    NASA Astrophysics Data System (ADS)

    Yoshida, tracking detectors T.; Sora, T.

    2004-12-01

    We have evaluated the performance of a prototype 16-channel avalanche photodiode (APD) array developed primarily for scintillating-fiber (SCIFI) tracking detectors. The APD array was coupled to a 2.5 m long SCIFI array, and the detection efficiency was measured for minimum ionizing particles passing through the SCIFI array. The APD array was cooled to -50 °C to improve the S/N ratio. We have found that the APD array can read out each individual SCIFI with sufficiently high efficiency.

  2. Application of a LED-photodiode optocouple for the study of human respiratory function

    NASA Astrophysics Data System (ADS)

    Malyshev, A. G.; Zhumashev, N. K.; Lukyanov, G. N.; Mynbaev, K. D.; Rassadina, A. A.

    2015-11-01

    Application of a LED-photodiode optocouple for the study of human respiratory function is considered. The optocouple operating in the middle-infrared part of the spectrum (with the peak of the LED emission at 4.1 μm at 300 K) was applied for monitoring changes in CO2 concentration during respiration of a human. Studies were carried out simultaneously with the measurements of pressure in the left and right halves of the nose cavity. The results of the study open possibilities for using infrared optocouples as sensitive elements in compact and cheap sensors detecting breath abnormalities associated with respiratory and other diseases.

  3. Ultrahigh-sensitivity single-photon detection with linear-mode silicon avalanche photodiode.

    PubMed

    Akiba, Makoto; Tsujino, Kenji; Sasaki, Masahide

    2010-08-01

    We developed an ultrahigh-sensitivity single-photon detector using a linear-mode avalanche photodiode (APD) with a cryogenic low-noise readout circuit; the APD is operated at 78K. The noise-equivalent power of the detector is as low as 2.2x10(-20)W/Hz(1/2) at a wavelength of 450nm. The photon-detection efficiency and dark-count rate (DCR) are 0.72 and 0.0008counts/s, respectively. A low DCR is achieved by thermal treatment for reducing the trapped carriers when the thermal treatment temperature is above 100K. PMID:20680078

  4. A photodiode-based neutral particle bolometer for characterizing charge-exchanged fast-ion behavior.

    PubMed

    Clary, R; Smirnov, A; Dettrick, S; Knapp, K; Korepanov, S; Ruskov, E; Heidbrink, W W; Zhu, Y

    2012-10-01

    A neutral particle bolometer (NPB) has been designed and implemented on Tri Alpha Energy's C-2 device in order to spatially and temporally resolve the charge-exchange losses of fast-ion populations originating from neutral beam injection into field-reversed configuration plasmas. This instrument employs a silicon photodiode as the detection device with an integrated tungsten filter coating to reduce sensitivity to light radiation. Here we discuss the technical aspects and calibration of the NPB, and report typical NPB measurement results of wall recycling effects on fast-ion losses. PMID:23126887

  5. Active quenching circuit for single-photon detection with Geiger mode avalanche photodiodes.

    PubMed

    Stipcević, Mario

    2009-03-20

    In this paper a novel construction of an active quenching circuit intended for single-photon detection is presented, along with a few original methods for its evaluation. The circuit has been combined with a standard avalanche photodiode C30902S to form a single-photon detector. This detector has a dead time of 39 ns, maximum random counting frequency of 14 MHz, small afterpulsing probability, an estimated peak detection efficiency of over 20%, and a dark count rate of less than 100 Hz. This simple and robust active quenching circuit can be built from off-the-shelf electronic components and is presented with the detailed schematic diagram. PMID:19305468

  6. The 1.06 micrometer avalanche photodiode detectors with integrated circuit preamplifiers

    NASA Technical Reports Server (NTRS)

    Eden, R. C.

    1975-01-01

    The development of a complete solid state 1.06 micron optical receiver which can be used in optical communications at data rates approaching 1.5 Gb/s, or in other applications requiring sensitive, short-pulse detection, is reported. This work entailed both the development of a new type of heterojunction 3-5 semiconductor alloy avalanche photodiode and an extremely charge-sensitive wideband low-noise preamp design making use of GaAs Schottky barrier-gate field effect transistors.

  7. Conceptual design and applications of HgCdTe infrared photodiodes for heterodyne systems

    NASA Technical Reports Server (NTRS)

    Sirieix, M. B.; Hofheimer, H.

    1980-01-01

    The significance of HgCdTe photodiodes are discussed relative to their existance in heterodyne detection systems operating in the 9 to 11 micrometer CO2 laser wavelength region. Their successful fabrication as well as the physical properties of the materials are described. The implementation of controlled industrial processes are reported with emphasis on the yield of predictable and repeatable detector characteristics to the discriminating systems, demands for high cutoff frequencies, quantum efficiency, and reliability. The most salient production steps and diode characteristics are presented. Measured results from production units are also given.

  8. Wavelength-division-multiplexed InGaAs/InP avalanched photodiodes for quantum key distributions

    NASA Astrophysics Data System (ADS)

    Lee, Moon Hyeok; Ha, Changkyun; Jeong, Heung-Sun; Kim, Dong Wook; Lee, Seoung Hun; Lee, Min Hee; Kim, Kyong Hon

    2016-02-01

    We demonstrate improved single photon detection efficiencies of InGaAs/InP avalanche photodiodes (APDs) in a wavelength-division-multiplexed (WDM) scheme for high-capacity plug-and-play-type two-way quantum key distributions (QKDs). Single-photon detectors (SPDs) combined in the WDM APD scheme can be used to overcome the detection speed limit of a single SPD which is caused mainly by the afterpulse effect. The multiple SPDs combined in the parallel WDM scheme can increase the single photon detection capacity, although additional optical losses resulted from the WDM MUX and deMUX devices induce limited increases.

  9. Required energy for a laser radar system incorporating a fiber amplifier or an avalanche photodiode.

    PubMed

    Overbeck, J A; Salisbury, M S; Mark, M B; Watson, E A

    1995-11-20

    The transmitted energy required for an airborne laser radar system to be able to image a target at 20 km is investigated. Because direct detection is being considered, two methods of enhancing the received signal are discussed: (1) using an avalanche photodiode (APD) as the detector and (2) using a commercial fiber amplifier as a preamplifier before a photodetector. For this analysis a specified signal-to-noise ratio was used in conjunction with the radar range equation, which includes the effects of atmospheric transmission and turbulence. Theoretical analysis reveals that a system with a fiber amplifier performs nearly the same as a system incorporating an APD. PMID:21060654

  10. Vacuum photodiode detectors for broadband vacuum ultraviolet detection in the Saha Institute of Nuclear Physics Tokamak

    NASA Astrophysics Data System (ADS)

    Rao, C. V. S.; Shankara Joisa, Y.; Hansalia, C. J.; Hui, Amit K.; Paul, Ratan; Ranjan, Prabhat

    1997-02-01

    We report on the application of the vacuum photodiode to detect vacuum ultraviolet (VUV) radiation emitted from the Saha Institute of Nuclear Physics (SINP) Tokamak. It is simple to fabricate and provides broadband spectral response in the VUV and ultrasoft x ray (10 eV-1 keV). In our design, a stainless steel photocathode is used, which has a response identical to tungsten in the wavelength range 100-1200 Å. Its surface is passivated, to minimize contamination and monolayer deposition, by electropolishing it. Some representative experimental results illustrating the range of applicability are presented with special emphasis on its performance in disruptive shots.

  11. Silicon-photodiode pyranometers: Operational characteristics, historical experiences, and new calibration procedures

    SciTech Connect

    King, D.L.; Myers, D.R.

    1997-11-01

    Small, low-cost, silicon-photodiode pyranometers are now widely used for solar irradiance measurements associated with solar thermal and photovoltaic power systems, as well as for agricultural applications. Without correction, the irradiance values indicated by these pyranometers may differ from the true broadband solar irradiance by over 10%. This paper identifies the time-of-day dependent factors responsible for these systematic errors, and describes new procedures that effectively compensate for the systematic influences. Application of the procedures should improve calibration methods and the accuracy of field measurements.

  12. GeSn-based p-i-n photodiodes with strained active layer on a Si wafer

    NASA Astrophysics Data System (ADS)

    Tseng, H. H.; Li, H.; Mashanov, V.; Yang, Y. J.; Cheng, H. H.; Chang, G. E.; Soref, R. A.; Sun, G.

    2013-12-01

    We report an investigation of GeSn-based p-i-n photodiodes with an active GeSn layer that is almost fully strained. The results show that (a) the response of the Ge/GeSn/Ge heterojunction photodiodes is stronger than that of the reference Ge-based photodiodes at photon energies above the 0.8 eV direct bandgap of bulk Ge (<1.55 μm), and (b) the optical response extends to lower energy regions (1.55-1.80 μm wavelengths) as characterized by the strained GeSn bandgap. A cusp-like spectral characteristic is observed for samples with high Sn contents, which is attributed to the significant strain-induced energy splitting of heavy and light hole bands. This work represents a step forward in developing GeSn-based infrared photodetectors.

  13. Type-II InAs/GaSb photodiode array pixel isolation by femto-second laser anneal

    NASA Astrophysics Data System (ADS)

    Das, Sona; Das, Utpal; Gautam, Nutan; Krishna, Sanjay

    2016-09-01

    A 775 nm, 150 fs laser anneal technique for increased inter-pixel isolation in type-II InAs/GaSb superlattice photodiode arrays (5.5 μ m cutoff wavelength) without mesa etch, is presented. With only p+ inter-pixel etch and fs laser anneal, a greater than two fold improvement in the inter-pixel isolation is observed at 70 K. A similar reduction in the dark current of p+ etched + fs laser annealed p-i-n photodiodes is observed at 70 K over un-passivated mesa etched photodiodes of 400 μ m pixel sizes, whereas in 55 μ m pixels a seven fold reduction in the surface component of dark current over un-passivated mesa etched diodes is achieved. An increased band gap of the inter-pixel region (∼ 10 meV) due to fs annealed intermixing has been calculated to be a possible reason for the improved inter-pixel isolation.

  14. Dual detection of ultraviolet and visible lights using a DNA-CTMA/GaN photodiode with electrically different polarity.

    PubMed

    Reddy, M Siva Pratap; Kim, Bong-Joong; Jang, Ja-Soon

    2014-01-13

    We demonstrated the dual-detectable DNA-CTMA/n-GaN photodiode (DG-PD) for ultraviolet and visible lights. Halogen and UV lamps are employed to recognize the visible and UV wavelength, respectively. The DG-PD under dark condition has a negative-bias shift of current-voltage (I-V) curves by 0.78 V compared to reference diode without DNA. However, the I-V curves move towards positive bias side by 0.75 V and 1.02 V for the halogen- and UV-exposed photodiode, respectively. These cause electrically different polarity and amount for halogen- and UV-induced photocurrents, indicating that the DNA-CTMA on n-GaN is quite effective for recognizing visible and UV lights as a dual-detectable photodiode. The formation and charge transport mechanisms are also discussed. PMID:24515050

  15. Pixel isolation in Type-II InAs/GaSb superlattice photodiodes by femto-second laser annealing

    NASA Astrophysics Data System (ADS)

    Das, Sona; Das, Utpal; Gautam, Nutan; Krishna, Sanjay

    2015-05-01

    A 775 nm femto-second laser annealed approach for the inter-pixel isolation, without mesa etching, to reduce dark currents of type-II InAs/GaSb superlattice photodiodes is presented. A greater than two fold improvement of the pixel isolation and a corresponding reduction in the dark current are observed for laser annealed superlattice photodiodes with a 5.5 μm cutoff wavelength, operating at 10K. A higher band gap barrier material from the superlattice structure in the inter-pixel region is expected to form after femto-second laser annealing, which has been explained on the basis of a superlattice inter-diffusion model. The increase in inter-pixel barrier height at 10K is estimated to be ~ 4 meV in the laser annealed superlattice photodiodes.

  16. Transient effects of ionizing radiation in Si, InGaAsP, GaAlSb, and Ge photodiodes

    SciTech Connect

    Wiczer, J. J.; Barnes, C. E.; Dawson, L. R.

    1980-01-01

    Certain military applications require the continuous operation of optoelectronic information transfer systems during exposure to ionizing radiation. In such an environment the optical detector can be the system element which limits data transmission. We report here the measured electrical and optical characteristics of an irradiation tolerant photodiode fabricated from a double heterojunction structure in the gallium aluminum antimonide (GaAlSb) ternary semiconductor system. A series of tests at Sandia Laboratories' Relativistic Electron Beam Accelerator (REBA) subjected this device and commercially available photodiodes (made from silicon, germanium, and indium gallium arsenide phosphide) to dose rate levels of 10/sup 7/ to 10/sup 8/ rads/sec. The results of these tests show that the thin GaAlSb double heterojunction photodiode structure generates significantly less unwanted radiation induced current density than that of the next best commercial device.

  17. Genotyping of Trypanosoma cruzi Sublineage in Human Samples from a North-East Argentina Area by Hybridization with DNA Probes and Specific Polymerase Chain Reaction (PCR)

    PubMed Central

    Diez, Cristina; Lorenz, Virginia; Ortiz, Silvia; Gonzalez, Verónica; Racca, Andrea; Bontempi, Iván; Manattini, Silvia; Solari, Aldo; Marcipar, Iván

    2010-01-01

    We have evaluated blood samples of chronic and congenital Trypanosoma cruzi-infected patients from the city of Reconquista located in the northeast of Argentina where no information was previously obtained about the genotype of infecting parasites. Fourteen samples of congenital and 19 chronical patients were analyzed by hybridization with DNA probes of minicircle hypervariable regions (mHVR). In congenital patients, 50% had single infections with TcIId, 7% single infections with TcIIe, 29% mixed infections with TcIId/e, and 7% had mixed infections with TcIId/b and 7% TcIId/b, respectively. In Chronical patients, 52% had single infections with TcIId, 11% single infections with TcIIe, 26% had mixed infections with TcIId/e, and 11% had non-identified genotypes. With these samples, we evaluated the minicircle lineage-specific polymerase chain reaction assay (MLS-PCR), which involves a nested PCR to HVR minicircle sequences and we found a correlation with hybridization probes of 96.4% for TcIId and 54.8% for TcIIe. PMID:20064998

  18. Application of the hybrid approach to the benchmark dose of urinary cadmium as the reference level for renal effects in cadmium polluted and non-polluted areas in Japan

    SciTech Connect

    Suwazono, Yasushi; Nogawa, Kazuhiro; Uetani, Mirei; Nakada, Satoru; Kido, Teruhiko; Nakagawa, Hideaki

    2011-02-15

    Objectives: The aim of this study was to evaluate the reference level of urinary cadmium (Cd) that caused renal effects. An updated hybrid approach was used to estimate the benchmark doses (BMDs) and their 95% lower confidence limits (BMDL) in subjects with a wide range of exposure to Cd. Methods: The total number of subjects was 1509 (650 men and 859 women) in non-polluted areas and 3103 (1397 men and 1706 women) in the environmentally exposed Kakehashi river basin. We measured urinary cadmium (U-Cd) as a marker of long-term exposure, and {beta}2-microglobulin ({beta}2-MG) as a marker of renal effects. The BMD and BMDL that corresponded to an additional risk (BMR) of 5% were calculated with background risk at zero exposure set at 5%. Results: The U-Cd BMDL for {beta}2-MG was 3.5 {mu}g/g creatinine in men and 3.7 {mu}g/g creatinine in women. Conclusions: The BMDL values for a wide range of U-Cd were generally within the range of values measured in non-polluted areas in Japan. This indicated that the hybrid approach is a robust method for different ranges of cadmium exposure. The present results may contribute further to recent discussions on health risk assessment of Cd exposure.

  19. Narrowband light detection via internal quantum efficiency manipulation of organic photodiodes.

    PubMed

    Armin, Ardalan; Jansen-van Vuuren, Ross D; Kopidakis, Nikos; Burn, Paul L; Meredith, Paul

    2015-01-01

    Spectrally selective light detection is vital for full-colour and near-infrared (NIR) imaging and machine vision. This is not possible with traditional broadband-absorbing inorganic semiconductors without input filtering, and is yet to be achieved for narrowband absorbing organic semiconductors. We demonstrate the first sub-100 nm full-width-at-half-maximum visible-blind red and NIR photodetectors with state-of-the-art performance across critical response metrics. These devices are based on organic photodiodes with optically thick junctions. Paradoxically, we use broadband-absorbing organic semiconductors and utilize the electro-optical properties of the junction to create the narrowest NIR-band photoresponses yet demonstrated. In this context, these photodiodes outperform the encumbent technology (input filtered inorganic semiconductor diodes) and emerging technologies such as narrow absorber organic semiconductors or quantum nanocrystals. The design concept allows for response tuning and is generic for other spectral windows. Furthermore, it is material-agnostic and applicable to other disordered and polycrystalline semiconductors. PMID:25721323

  20. Performances of amorphous silicon photodiodes integrated in chemiluminescence based μ-TAS

    NASA Astrophysics Data System (ADS)

    Caputo, Domenico; Nardini, Massimo; Scipinotti, Riccardo; de Cesare, Giampiero; Mirasoli, Mara; Zangheri, Martina; Roda, Aldo; Nascetti, Augusto

    2013-05-01

    A detailed characterization of the performances of amorphous silicon photodiodes in the detection of chemiluminescent signal is carried out. Comparison with commercial CCD acquisition system has been done as benchmark. The underlying idea is the development of stand-alone and compact micro-total-analysys-systems (μ-TAS) that do not need bulky and expensive equipment for their operation as external focusing optics and excitation sources. The photosensor is p-i-n structures deposited by Plasma Enhanced Chemical Vapour Deposition on a glass substrate covered with a transparent conductive oxide that acts as bottom electrode and window layer for the light impinging through the glass. A PDMS layer with wells has been fabricated using an aluminum mold and bonded on the glass substrate with a well aligned with a photosensor. The experiments have been performed by filling a well with solutions containing different quantities of horseradish peroxidase. A good linearity of the photosensor response is observed across the entire measurement range that spans over three orders of magnitude. The system detection limit is 70 fg/μL. A very good agreement between results achieved with conventional off-chip CCD detection and the on-chip photodiode has been observed. Experiments with target molecules immobilized on a functionalized glass surface have been also performed in microfluidic regime, confirming the validity of the proposed integrated approach based on a-Si:H technology.

  1. Narrowband light detection via internal quantum efficiency manipulation of organic photodiodes

    NASA Astrophysics Data System (ADS)

    Armin, Ardalan; Jansen-van Vuuren, Ross D.; Kopidakis, Nikos; Burn, Paul L.; Meredith, Paul

    2015-02-01

    Spectrally selective light detection is vital for full-colour and near-infrared (NIR) imaging and machine vision. This is not possible with traditional broadband-absorbing inorganic semiconductors without input filtering, and is yet to be achieved for narrowband absorbing organic semiconductors. We demonstrate the first sub-100 nm full-width-at-half-maximum visible-blind red and NIR photodetectors with state-of-the-art performance across critical response metrics. These devices are based on organic photodiodes with optically thick junctions. Paradoxically, we use broadband-absorbing organic semiconductors and utilize the electro-optical properties of the junction to create the narrowest NIR-band photoresponses yet demonstrated. In this context, these photodiodes outperform the encumbent technology (input filtered inorganic semiconductor diodes) and emerging technologies such as narrow absorber organic semiconductors or quantum nanocrystals. The design concept allows for response tuning and is generic for other spectral windows. Furthermore, it is material-agnostic and applicable to other disordered and polycrystalline semiconductors.

  2. UV and blue-enhanced avalanche photodiodes for nuclear spectroscopy applications

    NASA Astrophysics Data System (ADS)

    Gramsch, Ernesto; Avila, R. E.

    Avalanche photodiodes of the bevel-edge type have been developed with improved blue and UV response. The detectors have been characterized for use in low-light level applications such as nuclear spectroscopy. An etching technique not used before in avalanche photodiodes has been used to obtain improved blue and UV response. Quantum efficiency up to 40% has been obtained above 200 nm. The gain and dark current are dependent on external voltage, and gains up to 400 are obtained at 1980 V without excess noise, and breakdown occurs at ˜2000 V. The detector exhibits low noise and fast response, necessary for use in nuclear spectroscopy systems. The energy resolution from a 57Co gamma-ray source was measured to be 942 eV (6.4 keV X-rays), which corresponds to 111 r.m.s. noise electrons at the input. We measured the energy resolution of the detector coupled with a 3×3×3 mm 3 BGO scintillator from a 22Na gamma-ray source. The energy resolution at the 511 keV line was 12.5%, which is comparable to photomultiplier tubes coupled to a scintillator of the same size. The resolution with a 3×3×25 mm 3 LSO scintillator was also measured, the energy resolution at 511 keV was 12.1%.

  3. Development of Gated Pinned Avalanche Photodiode Pixels for High-Speed Low-Light Imaging.

    PubMed

    Resetar, Tomislav; De Munck, Koen; Haspeslagh, Luc; Rosmeulen, Maarten; Süss, Andreas; Puers, Robert; Van Hoof, Chris

    2016-01-01

    This work explores the benefits of linear-mode avalanche photodiodes (APDs) in high-speed CMOS imaging as compared to different approaches present in literature. Analysis of APDs biased below their breakdown voltage employed in single-photon counting mode is also discussed, showing a potentially interesting alternative to existing Geiger-mode APDs. An overview of the recently presented gated pinned avalanche photodiode pixel concept is provided, as well as the first experimental results on a 8 × 16 pixel test array. Full feasibility of the proposed pixel concept is not demonstrated; however, informative data is obtained from the sensor operating under -32 V substrate bias and clearly exhibiting wavelength-dependent gain in frontside illumination. The readout of the chip designed in standard 130 nm CMOS technology shows no dependence on the high-voltage bias. Readout noise level of 15 e - rms, full well capacity of 8000 e - , and the conversion gain of 75 µV / e - are extracted from the photon-transfer measurements. The gain characteristics of the avalanche junction are characterized on separate test diodes showing a multiplication factor of 1.6 for red light in frontside illumination. PMID:27537882

  4. Ge on Si waveguide-integrated photodiodes for high speed and low power receivers

    NASA Astrophysics Data System (ADS)

    Virot, Léopold; Vivien, Laurent; Hartmann, Jean Michel; Fédéli, Jean-Marc; Marris-Morini, Delphine; Cassan, Eric; Baudot, Charles; Boeuf, Frédéric

    2013-05-01

    Development of fast silicon photonics integrated circuit is mainly driven by the reduction of the power consumption. As a result, photodetectors with high efficiency, high speed and low dark current are needed to reduce the global link consumption. Germanium is now considered as the ideal candidate for fully integrated receivers based on SOI substrate and CMOS-like processes. We report on low power and high speed waveguide-integrated Ge photodetectors. Butt coupled lateral PIN structure photodiodes have been fabricated by Germanium selective growth and ion implantation at the end of silicon waveguide. Three types of photodiodes are reported, with dark current as low as 6nA at 1V reverse bias, optical bandwidth over 40GHz at zero bias and responsivity up to 0.8A/W at a wavelength of 1550nm. Such devices are suitable for data rate over 40Gbps and can be easily integrated with other photonic devices to fabricate wafer scale integrated circuits for datacom and telecom applications.

  5. 3D avalanche multiplication in Si-Ge lateral avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Jamil, Erum; Hayat, Majeed M.; Davids, Paul S.; Camacho, Ryan M.

    2016-05-01

    Si-Ge lateral avalanche photodiodes (Si-Ge LAPDs) are promising devices for single photon detection, but they also have technology challenges. Si-Ge LAPDs are CMOS compatible and capable of detecting photons near the 1550 nm telecommunications bands. However, the Si-Ge LAPD exhibits a unique avalanche multiplication process in silicon, where the electrons and holes follow curved paths in three-dimensional space. Traditional models for the analysis of the avalanche multiplication process assume one-dimensional paths for the carriers that undergo the chains of impact ionizations; therefore, they are not suitable for analyzing the avalanche properties of Si-Ge LAPDs. In this paper, the statistics of the avalanche process in the Si-Ge LAPD are modeled analytically using a method that was recently developed by our group for understanding the avalanche multiplication in nanopillar, core-shell GaAs avalanche photodiodes, for which the electric field is non-uniform in magnitude and direction. Specifically, the calculated mean avalanche gain and the excess noise are presented for the Si-Ge LAPD device. It is also shown that the avalanche characteristics depend upon the specific avalanche path taken by the carrier, which depends, in turn, on the lateral location where each photon is absorbed in the Ge absorber. This property can be exploited to achieve reduced excess noise as well as wavelength-sensitive single-photon detection.

  6. Light emitting diode, photodiode-based fluorescence detection system for DNA analysis with microchip electrophoresis.

    PubMed

    Hall, Gordon H; Glerum, D Moira; Backhouse, Christopher J

    2016-02-01

    Electrophoretic separation of fluorescently end-labeled DNA after a PCR serves as a gold standard in genetic diagnostics. Because of their size and cost, instruments for this type of analysis have had limited market uptake, particularly for point-of-care applications. This might be changed through a higher level of system integration and lower instrument costs that can be realized through the use of LEDs for excitation and photodiodes for detection--if they provide sufficient sensitivity. Here, we demonstrate an optimized microchip electrophoresis instrument using polymeric fluidic chips with fluorescence detection of end-labeled DNA with a LOD of 0.15 nM of Alexa Fluor 532. This represents orders of magnitude improvement over previously reported instruments of this type. We demonstrate the system with an electrophoretic separation of two PCR products and their respective primers. We believe that this is the first LED-induced fluorescence microchip electrophoresis system with photodiode-based detection that could be used for standard applications of PCR and electrophoresis. PMID:26412502

  7. Which Photodiode to Use: A Comparison of CMOS-Compatible Structures

    PubMed Central

    Murari, Kartikeya; Etienne-Cummings, Ralph; Thakor, Nitish; Cauwenberghs, Gert

    2010-01-01

    While great advances have been made in optimizing fabrication process technologies for solid state image sensors, the need remains to be able to fabricate high quality photosensors in standard CMOS processes. The quality metrics depend on both the pixel architecture and the photosensitive structure. This paper presents a comparison of three photodiode structures in terms of spectral sensitivity, noise and dark current. The three structures are n+/p-sub, n-well/p-sub and p+/n-well/p-sub. All structures were fabricated in a 0.5 μm 3-metal, 2-poly, n-well process and shared the same pixel and readout architectures. Two pixel structures were fabricated—the standard three transistor active pixel sensor, where the output depends on the photodiode capacitance, and one incorporating an in-pixel capacitive transimpedance amplifier where the output is dependent only on a designed feedback capacitor. The n-well/p-sub diode performed best in terms of sensitivity (an improvement of 3.5 × and 1.6 × over the n+/p-sub and p+/n-well/p-sub diodes, respectively) and signal-to-noise ratio (1.5 × and 1.2 × improvement over the n+/p-sub and p+/n-well/p-sub diodes, respectively) while the p+/n-well/p-sub diode had the minimum (33% compared to other two structures) dark current for a given sensitivity. PMID:20454596

  8. Photodiode-based cutting interruption sensor for near-infrared lasers.

    PubMed

    Adelmann, B; Schleier, M; Neumeier, B; Hellmann, R

    2016-03-01

    We report on a photodiode-based sensor system to detect cutting interruptions during laser cutting with a fiber laser. An InGaAs diode records the thermal radiation from the process zone with a ring mirror and optical filter arrangement mounted between a collimation unit and a cutting head. The photodiode current is digitalized with a sample rate of 20 kHz and filtered with a Chebyshev Type I filter. From the measured signal during the piercing, a threshold value is calculated. When the diode signal exceeds this threshold during cutting, a cutting interruption is indicated. This method is applied to sensor signals from cutting mild steel, stainless steel, and aluminum, as well as different material thicknesses and also laser flame cutting, showing the possibility to detect cutting interruptions in a broad variety of applications. In a series of 83 incomplete cuts, every cutting interruption is successfully detected (alpha error of 0%), while no cutting interruption is reported in 266 complete cuts (beta error of 0%). With this remarkable high detection rate and low error rate, the possibility to work with different materials and thicknesses in combination with the easy mounting of the sensor unit also to existing cutting machines highlight the enormous potential for this sensor system in industrial applications. PMID:26974642

  9. Updated design for a low-noise, wideband transimpedance photodiode amplifier

    SciTech Connect

    Paul, S. F.; Marsala, R.

    2006-10-15

    The high-speed rotation diagnostic developed for Columbia's HBT-EP tokamak requires a high quantum efficiency, very low drift detector/amplifier combination. An updated version of the circuit developed originally for the beam emission spectroscopy experiment on TFTR is being used. A low dark current (2 nA at 15 V bias), low input source capacitance (2 pF) FFD-040 N-type Si photodiode is operated in photoconductive mode. It has a quantum efficiency of 40% at the 468.6 nm (He II line that is being observed). A low-noise field-effect transistor (InterFET IFN152 with e{sub Na}=1.2 nV/{radical}Hz) is used to reduce the noise in the transimpedance preamplifier (A250 AMPTEK op-amp) and a very high speed (unity-gain bandwidth=200 MHz) voltage feedback amplifier (LM7171) is used to restore the frequency response up to 100 kHz. This type of detector/amplifier is photon-noise limited at this bandwidth for incident light with a power of >{approx}2 nW. The circuit has been optimized using SIMETRIX 4.0 SPICE software and a prototype circuit has been tested successfully. Though photomultipliers and avalanche photodiodes can detect much lower light levels, for light levels >2 nW and a 10 kHz bandwidth, this detector/amplifier combination is more sensitive because of the absence of excess (internally generated) noise.

  10. High Quantum Efficiency Nanopillar Photodiodes Overcoming the Diffraction Limit of Light.

    PubMed

    Lee, Wook-Jae; Senanayake, Pradeep; Farrell, Alan C; Lin, Andrew; Hung, Chung-Hong; Huffaker, Diana L

    2016-01-13

    InAs1-xSbx nanowires have recently attracted interest for infrared sensing applications due to the small bandgap and high thermal conductivity. However, previous reports on nanowire-based infrared sensors required low operating temperatures in order to mitigate the high dark current and have shown poor sensitivities resulting from reduced light coupling efficiency beyond the diffraction limit. Here, InAsSb nanopillar photodiodes with high quantum efficiency are achieved by partially coating the nanopillar with metal that excites localized surface plasmon resonances, leading to quantum efficiencies of ∼29% at 2390 nm. These high quantum efficiency nanopillar photodiodes, with 180 nm diameters and 1000 nm heights, allow operation at temperatures as high as 220 K and exhibit a detection wavelength up to 3000 nm, well beyond the diffraction limit. The InAsSb nanopillars are grown on low cost GaAs (111)B substrates using an InAs buffer layer, making our device architecture a promising path toward low-cost infrared focal plane arrays with high operating temperature. PMID:26682745

  11. Interplanetary space weather effects on Lunar Reconnaissance Orbiter avalanche photodiode performance

    NASA Astrophysics Data System (ADS)

    Clements, E. B.; Carlton, A. K.; Joyce, C. J.; Schwadron, N. A.; Spence, H. E.; Sun, X.; Cahoy, K.

    2016-05-01

    Space weather is a major concern for radiation-sensitive space systems, particularly for interplanetary missions, which operate outside of the protection of Earth's magnetic field. We examine and quantify the effects of space weather on silicon avalanche photodiodes (SiAPDs), which are used for interplanetary laser altimeters and communications systems and can be sensitive to even low levels of radiation (less than 50 cGy). While ground-based radiation testing has been performed on avalanche photodiode (APDs) for space missions, in-space measurements of SiAPD response to interplanetary space weather have not been previously reported. We compare noise data from the Lunar Reconnaissance Orbiter (LRO) Lunar Orbiter Laser Altimeter (LOLA) SiAPDs with radiation measurements from the onboard Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument. We did not find any evidence to support radiation as the cause of changes in detector threshold voltage during radiation storms, both for transient detector noise and long-term average detector noise, suggesting that the approximately 1.3 cm thick shielding (a combination of titanium and beryllium) of the LOLA detectors is sufficient for SiAPDs on interplanetary missions with radiation environments similar to what the LRO experienced (559 cGy of radiation over 4 years).

  12. Reversed Three-Dimensional Visible Light Indoor Positioning Utilizing Annular Receivers with Multi-Photodiodes.

    PubMed

    Xu, Yinfan; Zhao, Jiaqi; Shi, Jianyang; Chi, Nan

    2016-01-01

    Exploiting the increasingly wide use of light emitting diodes (LEDs) lighting, in this paper we propose a reversed indoor positioning system (IPS) based on LED visible light communication (VLC) in order to improve indoor positioning accuracy. Unlike other VLC positioning systems, we employ two annular receivers with multi-photodiodes installed on the ceiling to locate the persons who carry LEDs. The basic idea is using multi-photodiodes to calculate the angle while using the received signal strength (RSS) method to calculate the distance. The experiment results show that the effective positioning range of the proposed system is 1.8 m when the distance between two receivers is 1.2 m. Moreover, a positioning error less than 0.2 m can be achieved under the condition that the radius of the PIN circle is between 0.16 m and 0.2 m, and the distance of the transmitter-receiver plane is less than 1.8 m, which will be effective in practice. PMID:27509504

  13. Enabling accurate photodiode detection of multiple optical traps by spatial filtering

    NASA Astrophysics Data System (ADS)

    Ott, Dino; Reihani, S. Nader S.; Oddershede, Lene B.

    2014-09-01

    Dual and multiple beam optical tweezers allow for advanced trapping geometries beyond single traps, however, these increased manipulation capabilities, usually complicate the detection of position and force. The accuracy of position and force measurements is often compromised by crosstalk between the detected signals, this crosstalk leading to a systematic error on the measured forces and distances. In dual-beam optical trapping setups, the two traps are typically orthogonal polarized and crosstalk can be minimized by inserting polarization optics in front of the detector, however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Moreover, the restriction to two orthogonal polarisation states limits the number of detectable traps to two. Here, we present an easy-to-implement simple method to efficiently eliminate cross-talk in dual beam setups.1 The technique is based on spatial filtering and is highly compatible with standard back-focal-plane photodiode based detection. The reported method significantly improves the accuracy of force-distance measurements, e.g., of single molecules, hence providing much more scientific value for the experimental efforts. Furthermore, it opens the possibility for fast and simultaneous photodiode based detection of multiple holographically generated optical traps.

  14. Modelling and measurement of the absolute level of power radiated by antenna integrated THz UTC photodiodes.

    PubMed

    Natrella, Michele; Liu, Chin-Pang; Graham, Chris; van Dijk, Frederic; Liu, Huiyun; Renaud, Cyril C; Seeds, Alwyn J

    2016-05-30

    We determine the output impedance of uni-travelling carrier (UTC) photodiodes at frequencies up to 400 GHz by performing, for the first time, 3D full-wave modelling of detailed UTC photodiode structures. In addition, we demonstrate the importance of the UTC impedance evaluation, by using it in the prediction of the absolute power radiated by an antenna integrated UTC, over a broad frequency range and confirming the predictions by experimental measurements up to 185 GHz. This is done by means of 3D full-wave modelling and is only possible since the source (UTC) to antenna impedance match is properly taken into account. We also show that, when the UTC-to-antenna coupling efficiency is modelled using the classical junction-capacitance/series-resistance concept, calculated and measured levels of absolute radiated power are in substantial disagreement, and the maximum radiated power is overestimated by a factor of almost 7 dB. The ability to calculate the absolute emitted power correctly enables the radiated power to be maximised through optimisation of the UTC-to-antenna impedance match. PMID:27410104

  15. Design and evaluation of a 2D array PIN photodiode bump bonded to readout IC for the low energy x-ray detector.

    PubMed

    Yuk, Sunwoo; Park, Shin-Woong; Yi, Yun

    2006-01-01

    A 2D array radiation sensor, consisting of an array of PIN photodiodes bump bonded to readout integrated circuit (IC), has been developed for operation with low energy X-rays. The PIN photodiode array and readout IC for this system have been fabricated. The main performance measurements are the following: a few pA-scale leakage current, 350 pF junction capacitance, 30 microm-depth depletion layer and a 250 microm intrinsic layer at zero bias. This PIN photodiode array and readout IC were fabricated using a PIN photodiode process and standard 0.35 microm CMOS technology, respectively. The readout circuit is operated from a 3.3 V single power supply. Finally, a 2D array radiation sensor has been developed using bump bonding between the PIN photodiode and the readout electronics. PMID:17946079

  16. Thick, segmented CdWO{sub 4}-photodiode detector for cone beam megavoltage CT: A Monte Carlo study of system design parameters

    SciTech Connect

    Monajemi, T. T.; Fallone, B. G.; Rathee, S.

    2006-12-15

    Megavoltage (MV) imaging detectors have been the focus of research by many groups in recent years. We have been working with segmented CdWO{sub 4} crystals in contact with photodiodes in our lab. The present study uses both x-ray and optical photon transport Monte Carlo simulations to analyze the effects of scintillation crystal height, septa material, beam divergence, and beam spectrum on the modulation transfer function, MTF(f) and zero frequency detective quantum efficiency, DQE(0), of a theoretical area detector. The theoretical detector is comprised of tall, segmented CdWO{sub 4} crystals and two dimensional photodiode arrays with a pitch of 1 mm and a fill factor of 72%. Increasing the crystal height above 10 mm does not result in an improvement in the DQE(0) if the reflection coefficient of the septa is less than 0.8. For a reflection coefficient of 0.975 for the septa, there is a continual gain in the DQE(0) up to 30 mm tall crystals. Similar calculations show that employing a 3.5 MV beam without a flattening filter increases the DQE(0) for 20 mm tall crystals by 9% compared to a typical 6 MV beam with a flattening filter. The severe degradations due to beam divergence on MTF(f) are quantified and suggest the use of focused detectors in MV imaging. It is found that when the effect of optical photons is considered, the presence of divergence can appear as a shift in the location of the input signal as well as loss of spatial resolution.

  17. Optimization of a guard ring structure in Geiger-mode avalanche photodiodes fabricated at National NanoFab Center

    NASA Astrophysics Data System (ADS)

    Lim, K. T.; Kim, H.; Cho, M.; Kim, Y.; Kim, C.; Kim, M.; Lee, D.; Kang, D.; Yoo, H.; Park, K.; Sul, W. S.; Cho, G.

    2016-01-01

    A typical Geiger-mode avalanche photodiode (G-APD) contains a guard ring that protects the structure from having an edge breakdown due to the lowering of electric fields at junction curvatures. In this contribution, G-APDs with a virtual guard ring (vGR) merged with n-type diffused guard ring (nGR) in various sizes were studied to find the optimal design for G-APDs fabricated at National NanoFab Center (NNFC) . The sensors were fabricated via a customized CMOS process with a micro-cell size of 65× 65 μm2 on a 200 mm p-type epitaxial layer wafer. I-V characteristic curves for proposed structures were measured on a wafer-level with an auto probing system and plotted together to compare their performance. A vGR width of 1.5 μm and a nGR width of 1.5 μm with an overlapping between vGR and nGR of 1.5 μm showed the lowest leakage current before the breakdown voltage while suppressing the edge breakdown. Furthermore, the current level of the lowest-leakage-current structure was as low as that of only vGR with a width of 2.0 μm, indicating that the structure is also area efficient. Based on these results, the design with vGR, nGR, and OL with width of 1.5 μm is determined to be the optimal structure for G-APDs fabricated at NNFC.

  18. Cross-Species Hybridization with Fusarium verticillioides Microarrays Reveals New Insights into Fusarium fujikuroi Nitrogen Regulation and the Role of AreA and NMR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In filamentous fungi, the GATA-type transcription factor AreA plays a major role in transcriptional activation of genes needed to utilize poor nitrogen sources. Previously we have shown that in Fusarium fujikuroi AreA also controls genes involved in biosynthesis of nitrogen-free secondary metabolit...

  19. Hybrid photonic chip interferometer for embedded metrology

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Martin, H.; Maxwell, G.; Jiang, X.

    2014-03-01

    Embedded metrology is the provision of metrology on the manufacturing platform, enabling measurement without the removal of the work piece. Providing closer integration of metrology upon the manufacturing platform can lead to the better control and increased throughput. In this work we present the development of a high precision hybrid optical chip interferometer metrology device. The complete metrology sensor system is structured into two parts; optical chip and optical probe. The hybrid optical chip interferometer is based on a silica-on-silicon etched integrated-optic motherboard containing waveguide structures and evanescent couplers. Upon the motherboard, electro-optic components such as photodiodes and a semiconductor gain block are mounted and bonded to provide the required functionality. The key structure in the device is a tunable laser module based upon an external-cavity diode laser (ECDL). Within the cavity is a multi-layer thin film filter which is rotated to select the longitudinal mode at which the laser operates. An optical probe, which uses a blazed diffracting grating and collimating objective lens, focuses light of different wavelengths laterally over the measurand. Incident laser light is then tuned in wavelength time to effectively sweep an `optical stylus' over the surface. Wavelength scanning and rapid phase shifting can then retrieve the path length change and thus the surface height. We give an overview of the overall design of the final hybrid photonic chip interferometer, constituent components, device integration and packaging as well as experimental test results from the current version now under evaluation.

  20. Stellarator hybrids

    SciTech Connect

    Furth, H.P.; Ludescher, C.

    1984-08-01

    The present paper briefly reviews the subject of tokamak-stellarator and pinch-stellarator hybrids, and points to two interesting new possibilities: compact-torus-stellarators and mirror-stellarators.

  1. Al0.52In0.48P avalanche photodiodes for soft X-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Auckloo, A.; Cheong, J. S.; Meng, X.; Tan, C. H.; Ng, J. S.; Krysa, A.; Tozer, R. C.; David, J. P. R.

    2016-03-01

    The performance of Al0.52In0.48P avalanche photodiodes was assessed as soft X-ray detectors at room temperature. The effect of the avalanche gain improved the energy resolution and an energy resolution (FWHM) of 682 eV is reported for 5.9 keV X-rays.

  2. Final report on LDRD project 105967 : exploring the increase in GaAs photodiode responsivity with increased neutron fluence.

    SciTech Connect

    Blansett, Ethan L.; Geib, Kent Martin; Cich, Michael Joseph; Wrobel, Theodore Frank; Peake, Gregory Merwin; Fleming, Robert M.; Serkland, Darwin Keith; Wrobel, Diana L.

    2008-01-01

    A previous LDRD studying radiation hardened optoelectronic components for space-based applications led to the result that increased neutron irradiation from a fast-burst reactor caused increased responsivity in GaAs photodiodes up to a total fluence of 4.4 x 10{sup 13} neutrons/cm{sup 2} (1 MeV Eq., Si). The silicon photodiodes experienced significant degradation. Scientific literature shows that neutrons can both cause defects as well as potentially remove defects in an annealing-like process in GaAs. Though there has been some modeling that suggests how fabrication and radiation-induced defects can migrate to surfaces and interfaces in GaAs and lead to an ordering effect, it is important to consider how these processes affect the performance of devices, such as the basic GaAs p-i-n photodiode. In this LDRD, we manufactured GaAs photodiodes at the MESA facility, irradiated them with electrons and neutrons at the White Sands Missile Range Linac and Fast Burst Reactor, and performed measurements to show the effect of irradiation on dark current, responsivity and high-speed bandwidth.

  3. Low-Timing-Jitter Near-Infrared Single-Photon-Sensitive 16-Channel Intensified-Photodiode Detector

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Lu, Wei; Yang, Guangning; Sun, Xiaoli; Sykora, Derek; Jurkovic, Mike; Aebi, Verle; Costello, Ken; Burns, Richard

    2011-01-01

    We developed a 16-channel InGaAsP photocathode intensified-photodiode (IPD) detector with 78 ps (1-sigma) timing-jitter, less than 500 ps FWHM impulse response, greater than 15% quantum efficiency at 1064 nm wavelength with 131 kcps dark counts at 15 C.

  4. A primary standard of optical power based on induced-junction silicon photodiodes operated at room temperature

    NASA Astrophysics Data System (ADS)

    Dönsberg, Timo; Sildoja, Meelis; Manoocheri, Farshid; Merimaa, Mikko; Petroff, Leo; Ikonen, Erkki

    2014-06-01

    We present the design and construction of a new compact room temperature predictable quantum efficient detector (PQED). It consists of two custom-made induced-junction photodiodes mounted in a wedge trap configuration and a window aligned at Brewster's angle for high transmission of p polarized light. The window can also be removed, in which case a dry nitrogen flow system is utilized to prevent dust contamination of the photodiodes. Measurements of individual detectors at the wavelength of 488 nm indicate that reflectance and spectral responsivity are consistent within 4 ppm and 13 ppm peak-to-peak variation, respectively, and agree with the predicted values. The spatial non-uniformity of the responsivity of the PQED is an order of magnitude lower than that of single photodiodes. The internal quantum efficiency of the photodiodes is concluded to be spatially uniform within 50 ppm. These measurement results—together with the responsivity predictable by fundamental laws of physics—provide evidence that the room temperature PQED may replace the cryogenic radiometer as a primary standard of optical power in the visible wavelength range of 380 nm to 780 nm.

  5. Reset noise suppression in two-dimensional CMOS photodiode pixels through column-based feedback-reset

    NASA Technical Reports Server (NTRS)

    Pain, B.; Cunningham, T. J.; Hancock, B.; Yang, G.; Seshadri, S.; Ortiz, M.

    2002-01-01

    We present new CMOS photodiode imager pixel with ultra-low read noise through on-chip suppression of reset noise via column-based feedback circuitry. The noise reduction is achieved without introducing any image lag, and with insignificant reduction in quantum efficiency and full well.

  6. Numerical simulation of millisecond laser-induced damage in silicon-based positive-intrinsic-negative photodiode.

    PubMed

    Li, Zewen; Wang, Xi; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu

    2012-05-10

    An axisymmetric mathematical model was established for millisecond-pulsed Nd:YAG laser heating of silicon-based positive-intrinsic-negative photodiode. The transient temperature fields were obtained by using the finite element method. The temperature dependences of the material parameters and the absorption coefficient were taken into account in the calculation. The results indicate that the optical absorption coefficient and the thermal conductivity are the two key factors for the temperature evolution. The diffusion of boron in the liquid phase and the introduction of deep-level defects in the depletion region of the photodiode were the two reasons for the millisecond laser-induced electrical degradation of the photodiode. The morphological damage threshold and electrical degradation threshold of the photodiode were obtained numerically. Meanwhile, the influence of the antireflection coating, the doping concentration, and the junction depth were also considered. The results show that the morphological damage threshold decreases with adding an antireflection coating, the increase of the doping concentration, and junction depth. The electrical degradation threshold increases only with the junction depth. PMID:22614501

  7. Radiation effects induced in pin photodiodes by 40- and 85-MeV protons

    NASA Technical Reports Server (NTRS)

    Becher, J.; Kernell, R. L.; Reft, C. S.

    1985-01-01

    PIN photodiodes were bombarded with 40- and 85-MeV protons to a fluence of 1.5 x 10 to the 11th power p/sq cm, and the resulting change in spectral response in the near infrared was determined. The photocurrent, dark current and pulse amplitude were measured as a function of proton fluence. Changes in these three measured properties are discussed in terms of changes in the diode's spectral response, minority carrier diffusion length and depletion width. A simple model of induced radiation effects is presented which is in good agreement with the experimental results. The model assumes that incident protons produce charged defects within the depletion region simulating donor type impurities.

  8. Analysis of genetically modified organisms by pyrosequencing on a portable photodiode-based bioluminescence sequencer.

    PubMed

    Song, Qinxin; Wei, Guijiang; Zhou, Guohua

    2014-07-01

    A portable bioluminescence analyser for detecting the DNA sequence of genetically modified organisms (GMOs) was developed by using a photodiode (PD) array. Pyrosequencing on eight genes (zSSIIb, Bt11 and Bt176 gene of genetically modified maize; Lectin, 35S-CTP4, CP4EPSPS, CaMV35S promoter and NOS terminator of the genetically modified Roundup ready soya) was successfully detected with this instrument. The corresponding limit of detection (LOD) was 0.01% with 35 PCR cycles. The maize and soya available from three different provenances in China were detected. The results indicate that pyrosequencing using the small size of the detector is a simple, inexpensive, and reliable way in a farm/field test of GMO analysis. PMID:24518318

  9. Linear Mode HgCdTe Avalanche Photodiodes for Photon Counting Applications

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  10. Predictions of silicon avalanche photodiode detector performance in water vapor differential absorption lidar

    NASA Technical Reports Server (NTRS)

    Kenimer, R. L.

    1988-01-01

    Performance analyses are presented which establish that over most of the range of signals expected for a down-looking differential absorption lidar (DIAL) operated at 16 km the silicon avalanche photodiode (APD) is the preferred detector for DIAL measurements of atmospheric water vapor in the 730 nm spectral region. The higher quantum efficiency of the APD's, (0.8-0.9) compared to a photomultiplier's (0.04-0.18) more than offsets the higher noise of an APD receiver. In addition to offering lower noise and hence lower random error the APD's excellent linearity and impulse recovery minimize DIAL systematic errors attributable to the detector. Estimates of the effect of detector system parameters on overall random and systematic DIAL errors are presented, and performance predictions are supported by laboratory characterization data for an APD receiver system.

  11. Application of PN and avalanche silicon photodiodes to low-level optical

    NASA Technical Reports Server (NTRS)

    Eppeldauer, G.; Schaefer, A. R.

    1988-01-01

    New approaches to the discovery of other planetary systems require very sensitive and stable detection techniques in order to succeed. Two methods in particular, the astrometric and the photometric methods, require this. To begin understanding the problems and limitations of solid state detectors regarding this application, preliminary experiments were performed at the National Bureau of Standards and a low light level detector characterization facility was built. This facility is briefly described, and the results of tests conducted in it are outlined. A breadboard photometer that was used to obtain stellar brightness ratio precision data is described. The design principles of PN and avalanche silicon photodiodes based on low light level measuring circuits are discussed.

  12. Polarization engineering of back-illuminated separate absorption and multiplication AlGaN avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Yang, Guofeng; Wang, Fuxue

    2016-08-01

    The back-illuminated separate absorption and multiplication AlGaN avalanche photodiodes (APDs) with a p-type graded AlGaN layer have been designed to investigate the polarization engineering on the performance of the devices. The calculated results show that the APD with p-graded AlGaN layer exhibits lower avalanche breakdown voltage and increased maximum multiplication gain compared to the structure with conventional p-type AlGaN layer. The improved performance of the designed APD is numerically explained by the polarization-assisted enhancement of the ionization electric field in the multiplication region and polarization doping effect caused by the p-type graded layer.

  13. Gain properties of doped GaAs/AlGaAs multiple quantum well avalanche photodiode structures

    NASA Technical Reports Server (NTRS)

    Menkara, H. M.; Wagner, B. K.; Summers, C. J.

    1995-01-01

    A comprehensive characterization has been made of the static and dynamical response of conventional and multiple quantum well (MQW) avalanche photodiodes (APDs). Comparison of the gain characteristics at low voltages between the MQW and conventional APDs show a direct experimental confirmation of a structure-induced carrier multiplication due to interband impact ionization. Similar studies of the bias dependence of the excess noise characteristics show that the low-voltage gain is primarily due to electron ionization in the MQW-APDS, and to both electron and hole ionization in the conventional APDS. For the doped MQW APDS, the average gain per stage was calculated by comparing gain data with carrier profile measurements, and was found to vary from 1.03 at low bias to 1.09 near avalanche breakdown.

  14. High range precision laser radar system using a Pockels cell and a quadrant photodiode

    NASA Astrophysics Data System (ADS)

    Jo, Sungeun; Kong, Hong Jin; Bang, Hyochoong; Kim, Jae-Wan; Jeon, Byoung Goo

    2016-05-01

    We have proposed and demonstrated a novel technique to measure distance with high range precision. To meet the stringent requirements of a variety of applications, range precision is an important specification for laser radar systems. Range precision in conventional laser radar systems is limited by several factors, namely laser pulse width, the bandwidth of a detector, the timing resolution of the time to digital converter, shot noise and timing jitters generated by electronics. The proposed laser radar system adopts a Pockels cell and a quadrant photodiode and only measures the energy of a laser pulse to obtain range so that the effect of those factors is reduced in comparison to conventional systems. In the proposed system, the measured range precision was 5.7 mm with 100 laser pulses. The proposed method is expected to be an alternative method for laser radar system requiring high range precision in many applications.

  15. p-Cu2O-shell/n-TiO2-nanowire-core heterostucture photodiodes

    PubMed Central

    2011-01-01

    This study reports the deposition of cuprous oxide [Cu2O] onto titanium dioxide [TiO2] nanowires [NWs] prepared on TiO2/glass templates. The average length and average diameter of these thermally oxidized and evaporated TiO2 NWs are 0.1 to 0.4 μm and 30 to 100 nm, respectively. The deposited Cu2O fills gaps between the TiO2 NWs with good step coverage to form nanoshells surrounding the TiO2 cores. The p-Cu2O/n-TiO2 NW heterostructure exhibits a rectifying behavior with a sharp turn-on at approximately 0.9 V. Furthermore, the fabricated p-Cu2O-shell/n-TiO2-nanowire-core photodiodes exhibit reasonably large photocurrent-to-dark-current contrast ratios and fast responses. PMID:22040099

  16. Sounding rocket measurement of the absolute solar EUV flux utilizing a silicon photodiode

    NASA Technical Reports Server (NTRS)

    Ogawa, H. S.; Mcmullin, D.; Judge, D. L.; Canfield, L. R.

    1990-01-01

    A newly developed stable and high quantum efficiency silicon photodiode was used to obtain an accurate measurement of the integrated absolute magnitude of the solar extreme UV photon flux in the spectral region between 50 and 800 A. The adjusted daily 10.7-cm solar radio flux and sunspot number were 168.4 and 121, respectively. The unattenuated absolute value of the solar EUV flux at 1 AU in the specified wavelength region was 6.81 x 10 to the 10th photons/sq cm per s. Based on a nominal probable error of 7 percent for National Institute of Standards and Technology detector efficiency measurements in the 50- to 500-A region (5 percent on longer wavelength measurements between 500 and 1216 A), and based on experimental errors associated with the present rocket instrumentation and analysis, a conservative total error estimate of about 14 percent is assigned to the absolute integral solar flux obtained.

  17. High-resolution mapping of quantum efficiency of silicon photodiode via optical-feedback laser microthermography

    SciTech Connect

    Cemine, Vernon Julius; Blanca, Carlo Mar; Saloma, Caesar

    2006-09-20

    We map the external quantum efficiency (QE) distribution of a silicon photodiode (PD) sample via a thermographic imaging technique based on optical-feedback laser confocal microscopy. An image pair consisting of the confocal reflectance image and the 2D photocurrent map is simultaneously acquired to delineate the following regions of interest on the sample: the substrate, the n-type region, the pn overlay, and the bonding pad. The 2D QE distribution is derived from the photocurrent map to quantify the optical performance of these sites. The thermal integrity of the sample is then evaluated by deriving the rate of change of QE with temperature T at each point on the silicon PD. These gradient maps function not only as stringent measures of local thermal QE activity but they also expose probable defect locations on the sample at high spatial resolution - a capability that is not feasible with existing bulk measurement techniques.

  18. A method to precisely identify the afterpulses when using the S9717 avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Rusu, Alexandru; Rusu, Lucian

    2015-12-01

    The detection ratio of an avalanche photodiode (APD) biased in Geiger-mode increases versus the excess voltage; the afterpulsing rate increases too. The last one can be reduced by inserting an artificial dead time and accepting a lower measuring top rate. So, in order to tune a single-photon detector system, it is necessary to exactly identify afterpulses and measure their rate; the experimental results are presented. When using the S9717 APD in Geiger-mode, the cathode to ground voltage waveform reveals the existence of a particular sequence of pulses: a usual one followed, within 1μs, by a least one appearing to have been generated for negative excess voltage values. All these characteristics are the signature of the afterpulsing generation. Based on this observation, we were able to precisely measure the afterpulsing rate.

  19. A method to precisely identify the afterpulses when using the S9717 avalanche photodiode

    SciTech Connect

    Rusu, Alexandru Rusu, Lucian

    2015-12-07

    The detection ratio of an avalanche photodiode (APD) biased in Geiger-mode increases versus the excess voltage; the afterpulsing rate increases too. The last one can be reduced by inserting an artificial dead time and accepting a lower measuring top rate. So, in order to tune a single-photon detector system, it is necessary to exactly identify afterpulses and measure their rate; the experimental results are presented. When using the S9717 APD in Geiger-mode, the cathode to ground voltage waveform reveals the existence of a particular sequence of pulses: a usual one followed, within 1μs, by a least one appearing to have been generated for negative excess voltage values. All these characteristics are the signature of the afterpulsing generation. Based on this observation, we were able to precisely measure the afterpulsing rate.

  20. Avoiding sensor blindness in Geiger mode avalanche photodiode arrays fabricated in a conventional CMOS process

    NASA Astrophysics Data System (ADS)

    Vilella, E.; Diéguez, A.

    2011-12-01

    The need to move forward in the knowledge of the subatomic world has stimulated the development of new particle colliders. However, the objectives of the next generation of colliders sets unprecedented challenges to the detector performance. The purpose of this contribution is to present a bidimensional array based on avalanche photodiodes operated in the Geiger mode to track high energy particles in future linear colliders. The bidimensional array can function in a gated mode to reduce the probability to detect noise counts interfering with real events. Low reverse overvoltages are used to lessen the dark count rate. Experimental results demonstrate that the prototype fabricated with a standard HV-CMOS process presents an increased efficiency and avoids sensor blindness by applying the proposed techniques.

  1. Silicon waveguide infrared photodiodes with >35 GHz bandwidth and phototransistors with 50 AW-1 response.

    PubMed

    Geis, M W; Spector, S J; Grein, M E; Yoon, J U; Lennon, D M; Lyszczarz, T M

    2009-03-30

    SOI CMOS compatible Si waveguide photodetectors are made responsive from 1100 to 1750 nm by Si+ implantation and annealing. Photodiodes have a bandwidth of >35 GHz, an internal quantum efficiency of 0.5 to 10 AW-1, and leakage currents of 0.5 nA to 0.5 microA. Phototransistors have an optical response of 50 AW-1 with a bandwidth of 0.2 GHz. These properties are related to carrier mobilities in the implanted Si waveguide. These detectors exhibit low optical absorption requiring lengths from <0.3 mm to 3 mm to absorb 50% of the incoming light. However, the high bandwidth, high quantum efficiency, low leakage current, and potentially high fabrication yields, make these devices very competitive when compared to other detector technologies. PMID:19333283

  2. Ultralow noise midwave infrared InAs-GaSb strain layer superlattice avalanche photodiode

    SciTech Connect

    Mallick, Shubhrangshu; Banerjee, Koushik; Ghosh, Siddhartha; Plis, Elena; Rodriguez, Jean Baptiste; Krishna, Sanjay; Grein, Christoph

    2007-12-10

    Eye-safe midwavelength infrared InAs-GaSb strain layer superlattice p{sup +}-n{sup -}-n homojunction avalanche photodiodes (APDs) grown by solid source molecular beam epitaxy were fabricated and characterized. Maximum multiplication gain of 1800 was measured at -20 V at 77 K. Excess noise factors between 0.8 and 1.2 were measured up to gain of 300. Gain of 200 was measured at 120 K. Exponential nature of the gain as a function of reverse bias along with low excess noise factor at higher gain confirms single carrier electron-only impact ionization in the avalanche regime. Decrease in the multiplication gain at higher temperatures correlates with standard APD characteristics.

  3. Ultralow noise midwave infrared InAs-GaSb strain layer superlattice avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Mallick, Shubhrangshu; Banerjee, Koushik; Ghosh, Siddhartha; Plis, Elena; Rodriguez, Jean Baptiste; Krishna, Sanjay; Grein, Christoph

    2007-12-01

    Eye-safe midwavelength infrared InAs-GaSb strain layer superlattice p+-n--n homojunction avalanche photodiodes (APDs) grown by solid source molecular beam epitaxy were fabricated and characterized. Maximum multiplication gain of 1800 was measured at -20V at 77K. Excess noise factors between 0.8 and 1.2 were measured up to gain of 300. Gain of 200 was measured at 120K. Exponential nature of the gain as a function of reverse bias along with low excess noise factor at higher gain confirms single carrier electron-only impact ionization in the avalanche regime. Decrease in the multiplication gain at higher temperatures correlates with standard APD characteristics.

  4. Photodiode-based sensor for flame sensing and combustion-process monitoring.

    PubMed

    Arias, Luis; Torres, Sergio; Sbarbaro, Daniel; Farias, Oscar

    2008-10-10

    A nonintrusive low-cost sensor based on silicon photodiode detectors has been designed to analyze the formation and behavior of excited CH(*) and C(2)(*) radicals in the combustion process by sensing the spectral emission of hydrocarbon flames. The sensor was validated by performing two sets of experiments for both nonconfined and confined flames. For a nonconfined oil flame, the sensor responses for the axial intensity were highly correlated with the measurements obtained with a radiometer. For confined gas flames the ratio between the signal corresponding to C(2)(*) and CH(*) was successfully correlated with the CO pollutant emissions and the combustion efficiency. These results give additional insight on how to prevent an incomplete combustion using spectral information. The fast response, the nonintrusive character, and the instantaneous measurement of the needed spectral information makes the proposed optical sensor a key element in the development of advanced control strategies for combustion processes. PMID:18846197

  5. Properties of avalanche photodiodes for applications in high energy physics, astrophysics and medical imaging

    NASA Astrophysics Data System (ADS)

    Renker, Dieter

    2002-06-01

    Avalanche Photodiodes (APDs) with reverse structure and very good sensitivity to visible light are the first time used in large scale for the readout of PbWO 4 crystals in the barrel of the CMS electromagnetic calorimeter. They have to operate in a rather hostile environment, in a magnetic field of 4 T and under unprecedented radiation levels for a minimum of 10 years with a failure rate substantially lower than 1%. After an extensive R&D work the mass production started recently. The properties of the APDs and the possibilities for modifications of some parameters for other applications will be discussed. Particularly interesting is the status of APD arrays and the prospects of their development for PET scanners and for X-ray imaging.

  6. Spectrally dependent photovoltages in Schottky photodiode based on (100) B-doped diamond

    SciTech Connect

    Čermák, Jan Rezek, Bohuslav; Koide, Yasuo; Takeuchi, Daisuke

    2014-02-07

    Spectrally and spatially resolved photovoltages were measured by Kelvin probe force microscopy (KPFM) on a Schottky photo-diode made of a 4 nm thin tungsten-carbide (WC) layer on a 500 nm oxygen-terminated boron-doped diamond epitaxial layer (O-BDD) that was grown on a Ib (100) diamond substrate. The diode was grounded by the sideways ohmic contact (Ti/WC), and the semitransparent Schottky contact was let unconnected. The electrical potentials across the device were measured in dark (only 650 nm LED of KPFM being on), under broad-band white light (halogen lamp), UV (365 nm diode), and deep ultraviolet (deuterium lamp) illumination. Illumination induced shift of the electrical potential remains within 210 mV. We propose that the photovoltage actually corresponds to a shift of Fermi level inside the BDD channel and thereby explains orders of magnitude changes in photocurrent.

  7. Measurement of charge transfer potential barrier in pinned photodiode CMOS image sensors

    NASA Astrophysics Data System (ADS)

    Chen, Cao; Bing, Zhang; Junfeng, Wang; Longsheng, Wu

    2016-05-01

    The charge transfer potential barrier (CTPB) formed beneath the transfer gate causes a noticeable image lag issue in pinned photodiode (PPD) CMOS image sensors (CIS), and is difficult to measure straightforwardly since it is embedded inside the device. From an understanding of the CTPB formation mechanism, we report on an alternative method to feasibly measure the CTPB height by performing a linear extrapolation coupled with a horizontal left-shift on the sensor photoresponse curve under the steady-state illumination. The theoretical study was performed in detail on the principle of the proposed method. Application of the measurements on a prototype PPD-CIS chip with an array of 160 × 160 pixels is demonstrated. Such a method intends to shine new light on the guidance for the lag-free and high-speed sensors optimization based on PPD devices. Project supported by the National Defense Pre-Research Foundation of China (No. 51311050301095).

  8. Ge/Si heterojunction photodiodes fabricated by low temperature wafer bonding.

    PubMed

    Gity, Farzan; Daly, Aidan; Snyder, Bradley; Peters, Frank H; Hayes, John; Colinge, Cindy; Morrison, Alan P; Corbett, Brian

    2013-07-15

    We report on the photoresponse of an asymmetrically doped p(-)-Ge/n(+)-Si heterojunction photodiode fabricated by wafer bonding. Responsivities in excess of 1 A/W at 1.55 μm are measured with a 5.4 μm thick Ge layer under surface-normal illumination. Capacitance-voltage measurements show that the interfacial band structure is dependent on both temperature and light level, moving from depletion of holes at -50 °C to accumulation at 20 °C. Interface traps filled by photo-generated and thermally-generated carriers are shown to play a crucial role. Their filling alters the potential barrier height at the interface leading to increased flow of dark current and the above unity responsivity. PMID:23938577

  9. All-solution based device engineering of multilayer polymeric photodiodes: Minimizing dark current

    NASA Astrophysics Data System (ADS)

    Keivanidis, Panagiotis E.; Khong, Siong-Hee; Ho, Peter K. H.; Greenham, Neil C.; Friend, Richard H.

    2009-04-01

    We present photodiodes fabricated with several layers of semiconducting polymers, designed to show low dark current under reverse bias operation. Dark current minimization is achieved through the presence of additional polymer layers that reduce charge carrier injection in reverse bias, when in contact with the device electrodes. All polymer layers are deposited via spin coating and are photocross-linked for allowing further polymer layer deposition, by using a bis-fluorinated phenyl-azide photocross-linking agent. Dark current density values as low as 40 pA/mm2 are achieved with a corresponding external quantum efficiency (EQE) of 20% at a reverse bias of -0.5 V when an electron-blocking layer is used. Dark current is further reduced when both an electron- and a hole-blocking layer are used but the EQE falls significantly.

  10. Supercontinuum Fourier transform spectrometry with balanced detection on a single photodiode

    DOE PAGESBeta

    Goncharov, Vasily; Hall, Gregory

    2016-08-25

    Here, we have developed phase-sensitive signal detection and processing algorithms for Fourier transform spectrometers fitted with supercontinuum sources for applications requiring ultimate sensitivity. Similar to well-established approach of source noise cancellation through balanced detection of monochromatic light, our method is capable of reducing the relative intensity noise of polychromatic light by 40 dB. Unlike conventional balanced detection, which relies on differential absorption measured with a well matched pair of photo-detectors, our algorithm utilizes phase-sensitive differential detection on a single photodiode and is capable of the real-time correction for instabilities in supercontinuum spectral structure over a broad range of wavelengths. Inmore » the resulting method is universal in terms of applicable wavelengths and compatible with commercial spectrometers. We present a proof-of-principle experimental« less

  11. Numerical analysis of single photon detection avalanche photodiodes operated in the Geiger mode

    NASA Astrophysics Data System (ADS)

    Sugihara, K.; Yagyu, E.; Tokuda, Y.

    2006-06-01

    For a wide range of the thicknesses of the charge and the multiplication layers, detection efficiency and dark count probability are numerically investigated for GaInAs/InP single photon detection avalanche photodiodes (APD's) which are operated in the Geiger mode. Breakdown probability and dark currents are calculated to evaluate detection efficiency and dark count probability. The result shows that dark count probability can be significantly reduced by increasing the thickness of the charge layer, whereas detection efficiency is expected to decline steeply at some thickness of the charge layer. Moreover, increasing the thickness of the multiplication layer does not continue to reduce dark count probability, which increases when the multiplication layer is thicker than a critical thickness. Finally, we show a design guideline of single photon detection APD's with higher detection efficiency and lower dark count probability.

  12. High-performance SWIR sensing from colloidal quantum dot photodiode arrays

    NASA Astrophysics Data System (ADS)

    Klem, Ethan; Lewis, Jay; Gregory, Chris; Cunningham, Garry; Temple, Dorota; D'Souza, Arvind; Robinson, Ernest; Wijewarnasuriya, P. S.; Dhar, Nibir

    2013-09-01

    RTI has demonstrated a novel photodiode technology based on IR-absorbing solution-processed PbS colloidal quantum dots (CQD) that can overcome the high cost, limited spectral response, and challenges in the reduction in pixel size associated with InGaAs focal plane arrays. The most significant advantage of the CQD technology is ease of fabrication. The devices can be fabricated directly onto the ROIC substrate at low temperatures compatible with CMOS, and arrays can be fabricated at wafer scale. Further, device performance is not expected to degrade significantly with reduced pixel size. We present results for upward-looking detectors fabricated on Si substrates with sensitivity from the UV to ~1.7 μm, compare these results to InGaAs detectors, and present measurements of the CQD detectors temperature dependent dark current.

  13. Traveling-wave Uni-Traveling Carrier photodiodes for continuous wave THz generation.

    PubMed

    Rouvalis, Efthymios; Renaud, Cyril C; Moodie, David G; Robertson, Michael J; Seeds, Alwyn J

    2010-05-24

    The design, experimental evaluation and performance of a Traveling-Wave Uni-Traveling Carrier photodiode for Terahertz generation are described and its advantages in terms of frequency response are demonstrated. The device delivered 148 microW at 457 GHz, 24 microW at 914 GHz when integrated with resonant antennas and 105 microW at 255 GHz, 30 microW at 408 GHz, 16 microW at 510 GHz and 10 microW at 612 GHz. Record levels of Terahertz figure of merit (PTHz/Popt2 in W(-1)) were achieved ranging from 1 W(-1) at 110 GHz to 0.0024 W(-1) at 914 GHz. PMID:20588968

  14. Spray coated indium-tin-oxide-free organic photodiodes with PEDOT:PSS anodes

    SciTech Connect

    Schmidt, Morten Falco, Aniello; Loch, Marius; Lugli, Paolo; Scarpa, Giuseppe

    2014-10-15

    In this paper we report on Indium Tin Oxide (ITO)-free spray coated organic photodiodes with an active layer consisting of a poly(3-hexylthiophen) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend and patterned poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) electrodes. External quantum efficiency and current voltage characteristics under illuminated and dark conditions as well as cut-off frequencies for devices with varying active and hole conducting layer thicknesses were measured in order to characterize the fabricated devices. 60% quantum efficiency as well as nearly four orders of magnitude on-off ratios have been achieved. Those values are comparable with standard ITO devices.

  15. Profiling and Quantitation of Bacterial Carotenoids by Liquid Chromatography and Photodiode Array Detection

    PubMed Central

    Nelis, H. J.; De Leenheer, A. P.

    1989-01-01

    An analytical method for the profiling and quantitative determination of carotenoids in bacteria is described. Exhaustive extraction of the pigments from four selected bacterial strains required treatment of the cells with potassium hydroxide or liquefied phenol or both before the addition of the extracting solvent (methanol or diethyl ether). The carotenoids in the extracts were separated by nonaqueous reversed-phase liquid chromatography in conjunction with photodiode array absorption detection. The identity of a peak was considered definitive only when both its retention time and absorption spectrum, before and after chemical reactions, matched those of a reference component. In the absence of the latter, most peaks could be tentatively identified. Two examples illustrate how in the analysis of pigmented bacteria errors may result from using nonchromatographic procedures or liquid chromatographic methods lacking sufficient criteria for peak identification. Carotenoids of interest were determined quantitatively when the authentic reference substance was available or, alternatively, were determined semiquantitatively. PMID:16348068

  16. Plasmonic field confinement for separate absorption-multiplication in InGaAs nanopillar avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Farrell, Alan C.; Senanayake, Pradeep; Hung, Chung-Hong; El-Howayek, Georges; Rajagopal, Abhejit; Currie, Marc; Hayat, Majeed M.; Huffaker, Diana L.

    2015-12-01

    Avalanche photodiodes (APDs) are essential components in quantum key distribution systems and active imaging systems requiring both ultrafast response time to measure photon time of flight and high gain to detect low photon flux. The internal gain of an APD can improve system signal-to-noise ratio (SNR). Excess noise is typically kept low through the selection of material with intrinsically low excess noise, using separate-absorption-multiplication (SAM) heterostructures, or taking advantage of the dead-space effect using thin multiplication regions. In this work we demonstrate the first measurement of excess noise and gain-bandwidth product in III-V nanopillars exhibiting substantially lower excess noise factors compared to bulk and gain-bandwidth products greater than 200 GHz. The nanopillar optical antenna avalanche detector (NOAAD) architecture is utilized for spatially separating the absorption region from the avalanche region via the NOA resulting in single carrier injection without the use of a traditional SAM heterostructure.

  17. Optoelectronic detection of millimetre-wave signals with travelling-wave uni-travelling carrier photodiodes.

    PubMed

    Rouvalis, Efthymios; Fice, Martyn J; Renaud, Cyril C; Seeds, Alwyn J

    2011-01-31

    Optically pumped mixing in travelling-wave uni-travelling carrier photodiodes is proposed as a novel technique for detecting millimetre-wave signals. An experimental demonstration was performed at a frequency of 100 GHz. From DC measurements, an increase in the responsivity was found at high levels of optical power. The mixing mechanism is attributed to the variation of the responsivity with the applied reverse bias and the optical input power. The maximum intermediate frequency power was found to be -35 dBm for a 4 dBm radio frequency power, while an average conversion loss of 40 dB was achieved. A wide dynamic range of more than 42 dB was measured, limited by the maximum available millimetre-wave power. PMID:21369024

  18. Micropixel avalanche photodiodes and the possibility for their application in positron-emission tomography

    NASA Astrophysics Data System (ADS)

    Anfimov, N. V.; Selyunin, A. S.

    2012-12-01

    Micropixel avalanche photodiodes (MAPDs) are new instruments for detecting low-intensity light. They consist of many microcounters (pixels integrated on a common silicon wafer). A unique design by the Joint Institute for Nuclear Research (JINR) (Z. Sadygov)—deep-microwell MAPD—provides an order of larger pixel densities without losses in photon-detection efficiency. These instruments are beginning to find use in precision electromagnetic calorimetry. MAPDs can be most widely applied as photodetectors in scanners for positron-emission tomographs (PETs), particularly the time-of-flight PETs becoming popular now. The possibility of using MAPDs in PETs is shown, and the time resolution of a pair of quanta detected by Lutetium Fine Silicate scintillation crystals with MAPD readout is obtained at the level of 400 ps.

  19. Supercontinuum Fourier transform spectrometry with balanced detection on a single photodiode

    SciTech Connect

    Goncharov, Vasily; Hall, Gregory

    2016-01-01

    Here, we have developed phase-sensitive signal detection and processing algorithms for Fourier transform spectrometers fitted with supercontinuum sources for applications requiring ultimate sensitivity. Similar to well-established approach of source noise cancellation through balanced detection of monochromatic light, our method is capable of reducing the relative intensity noise of polychromatic light by 40 dB. Unlike conventional balanced detection, which relies on differential absorption measured with a well matched pair of photo-detectors, our algorithm utilizes phase-sensitive differential detection on a single photodiode and is capable of the real-time correction for instabilities in supercontinuum spectral structure over a broad range of wavelengths. In the resulting method is universal in terms of applicable wavelengths and compatible with commercial spectrometers. We present a proof-of-principle experimental

  20. Characterization of total ionizing dose damage in COTS pinned photodiode CMOS image sensors

    NASA Astrophysics Data System (ADS)

    Wang, Zujun; Ma, Wuying; Huang, Shaoyan; Yao, Zhibin; Liu, Minbo; He, Baoping; Liu, Jing; Sheng, Jiangkun; Xue, Yuan

    2016-03-01

    The characterization of total ionizing dose (TID) damage in COTS pinned photodiode (PPD) CMOS image sensors (CISs) is investigated. The radiation experiments are carried out at a 60Co γ-ray source. The CISs are produced by 0.18-μm CMOS technology and the pixel architecture is 8T global shutter pixel with correlated double sampling (CDS) based on a 4T PPD front end. The parameters of CISs such as temporal domain, spatial domain, and spectral domain are measured at the CIS test system as the EMVA 1288 standard before and after irradiation. The dark current, random noise, dark signal non-uniformity (DSNU), photo response non-uniformity (PRNU), overall system gain, saturation output, dynamic range (DR), signal to noise ratio (SNR), quantum efficiency (QE), and responsivity versus the TID are reported. The behaviors of the tested CISs show remarkable degradations after radiation. The degradation mechanisms of CISs induced by TID damage are also analyzed.

  1. Unambiguous determination of carrier concentration and mobility for InAs/GaSb superlattice photodiode optimization

    SciTech Connect

    Cervera, C.; Rodriguez, J. B.; Perez, J. P.; Aiet-Kaci, H.; Chaghi, R.; Christol, P.; Konczewicz, L.; Contreras, S.

    2009-08-01

    In this communication we report on electrical properties of nonintentionally doped (nid) type II InAs/GaSb superlattice grown by molecular beam epitaxy. We present a simple technological process which, thanks to the suppression of substrate, allows direct Hall measurement on superlattice structures grown on conductive GaSb substrate. Two samples were used to characterize the transport: one grown on a semi-insulating GaAs substrate and another grown on n-GaSb substrate where a etch stop layer was inserted to remove the conductive substrate. Mobilities and carrier concentrations have been measured as a function of temperature (77-300 K), and compared with capacitance-voltage characteristic at 80 K of a photodiode comprising a similar nid superlattice.

  2. The performance of photon counting imaging with a Geiger mode silicon avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Qu, Hui-Ming; Zhang, Yi-Fan; Ji, Zhong-Jie; Chen, Qian

    2013-10-01

    In principle, photon counting imaging can detect a photon. With the development of low-level-light image intensifier techniques and low-level-light detection devices, photon counting imaging can now detect photon images under extremely low illumination. Based on a Geiger mode silicon avalanche photodiode single photon counter, an experimental system for photon counting imaging was built through two-dimensional scanning of a SPAD (single photon avalanche diode) detector. The feasibility of the imaging platform was validated experimentally. Two images with different characteristics, namely, the USAF 1951 resolution test panel and the image of Lena, were chosen to evaluate the imaging performance of the experimental system. The results were compared and analysed. The imaging properties under various illumination and scanning steps were studied. The lowest illumination limit of the SPAD photon counting imaging was determined.

  3. Germanium-tin multiple quantum well on silicon avalanche photodiode for photodetection at two micron wavelength

    NASA Astrophysics Data System (ADS)

    Dong, Yuan; Wang, Wei; Lee, Shuh Ying; Lei, Dian; Gong, Xiao; Khai Loke, Wan; Yoon, Soon-Fatt; Liang, Gengchiau; Yeo, Yee-Chia

    2016-09-01

    We report the demonstration of a germanium-tin multiple quantum well (Ge0.9Sn0.1 MQW)-on-Si avalanche photodiode (APD) for light detection near the 2 μm wavelength range. The measured spectral response covers wavelengths from 1510 to 2003 nm. An optical responsivity of 0.33 A W‑1 is achieved at 2003 nm due to the internal avalanche gain. In addition, a thermal coefficient of breakdown voltage is extracted to be 0.053% K‑1 based on the temperature-dependent dark current measurement. As compared to the traditional 2 μm wavelength APDs, the Si-based APD is promising for its small excess noise factor, less stringent demand on temperature stability, and its compatibility with silicon technology.

  4. Signal-to-noise ratio of Geiger-mode avalanche photodiode single-photon counting detectors

    NASA Astrophysics Data System (ADS)

    Kolb, Kimberly

    2014-08-01

    Geiger-mode avalanche photodiodes (GM-APDs) use the avalanche mechanism of semiconductors to amplify signals in individual pixels. With proper thresholding, a pixel will be either "on" (avalanching) or "off." This discrete detection scheme eliminates read noise, which makes these devices capable of counting single photons. Using these detectors for imaging applications requires a well-developed and comprehensive expression for the expected signal-to-noise ratio (SNR). This paper derives the expected SNR of a GM-APD detector in gated operation based on gate length, number of samples, signal flux, dark count rate, photon detection efficiency, and afterpulsing probability. To verify the theoretical results, carrier-level Monte Carlo simulation results are compared to the derived equations and found to be in good agreement.

  5. Practical photon number detection with electric field-modulated silicon avalanche photodiodes.

    PubMed

    Thomas, O; Yuan, Z L; Shields, A J

    2012-01-01

    Low-noise single-photon detection is a prerequisite for quantum information processing using photonic qubits. In particular, detectors that are able to accurately resolve the number of photons in an incident light pulse will find application in functions such as quantum teleportation and linear optics quantum computing. More generally, such a detector will allow the advantages of quantum light detection to be extended to stronger optical signals, permitting optical measurements limited only by fluctuations in the photon number of the source. Here we demonstrate a practical high-speed device, which allows the signals arising from multiple photon-induced avalanches to be precisely discriminated. We use a type of silicon avalanche photodiode in which the lateral electric field profile is strongly modulated in order to realize a spatially multiplexed detector. Clearly discerned multiphoton signals are obtained by applying sub-nanosecond voltage gates in order to restrict the detector current. PMID:22273682

  6. Liquid chromatographic-photodiode array mass spectrometric analysis of dietary phytoestrogens from human urine and blood.

    PubMed

    Franke, Adrian A; Custer, Laurie J; Wilkens, Lynne R; Le Marchand, Loïc Le; Nomura, Abraham M Y; Goodman, Marc T; Kolonel, Laurence N

    2002-09-25

    Dietary phytoestrogens have been implicated in the prevention of chronic diseases. However, it is uncertain whether the phytoestrogens or the foods associated with phytoestrogens account for the observed effects. We report here a new liquid chromatography photodiode array mass spectrometry (LC-PDA-MS) assay for the determination of nanomolar amounts of the most prominent dietary phytoestrogens (genistein, dihydrogenistein, daidzein, dihydrodaidzein, glycitein, O-desmethylangolensin, hesperetin, naringenin, quercetin, enterodiol, enterolactone) in human plasma or serum and urine. This assay was found to be suitable for the assessment of quercetin exposure in an onion intervention study by measuring urinary quercetin levels. Other successful applications of this assay in clinical and epidemiologic studies validated the developed method and confirmed previous results on the negative association between urinary isoflavone excretion and breast cancer risk. PMID:12270199

  7. High performance InAs/Ga1-xInxSb superlattice infrared photodiodes

    NASA Astrophysics Data System (ADS)

    Fuchs, F.; Weimer, U.; Pletschen, W.; Schmitz, J.; Ahlswede, E.; Walther, M.; Wagner, J.; Koidl, P.

    1997-12-01

    The optical and electrical properties of infrared photodiodes diodes based on InAs/(GaIn)Sb superlattices grown by molecular beam epitaxy were investigated. The diodes, with a cut-off wavelength around 8 μm show a current responsivity of 2 A/W. By proper adjustment of the p-doping level above the n-background concentration the depletion width exceeds a critical size of about 60 nm, leading to the suppression of band-to-band tunneling currents. Above that critical width the dynamic impedance R0A at 77 K reaches values above 1 kΩ cm2 leading to a Johnson-noise-limited detectivity in excess of 1×1012 cm√Hz/W.

  8. InAs/Ga1-xInxSb infrared superlattice photodiodes for infrared detection

    NASA Astrophysics Data System (ADS)

    Fuchs, Frank; Weimar, U.; Ahlswede, E.; Pletschen, Wilfried; Schmitz, J.; Walther, Martin

    1998-04-01

    Electric and optical properties of IR photodiodes based on InAs/(GaIn)Sb superlattices were investigations. Mesa diodes were fabricated with cut-off wavelengths ranging from 7.5 to 12 micrometers , showing 77 K detectivities between 1 X 1012 cmHz0.5/W and 5 X 1010 cmHz0.5/W, respectively. At least two leakage current mechanisms are observed in the reverse bias branch of the current-voltage characteristics. At high reverse bias band-to-band tunneling currents dominate. Close to zero voltage surface leakage currents become important. The leakage currents are studied with gate controlled mesa diodes, allowing depletion or inversion of the mesa side walls. In addition, the band-to- band tunneling currents are investigated by applying magnetic fields oriented parallel and perpendicular to the electric field across the p-n junction of the diode.

  9. Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation

    NASA Astrophysics Data System (ADS)

    Chern, Yann-Cherng; Wu, Hung-Ruei; Chen, Yen-Chu; Zan, Hsiao-Wen; Meng, Hsin-Fei; Horng, Sheng-Fu

    2015-08-01

    A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area as large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.

  10. Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation

    SciTech Connect

    Chern, Yann-Cherng; Wu, Hung-Ruei; Chen, Yen-Chu; Horng, Sheng-Fu; Zan, Hsiao-Wen; Meng, Hsin-Fei

    2015-08-15

    A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area as large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.

  11. Linear mode photon counting with the noiseless gain HgCdTe e-avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Beck, Jeffrey D.; Scritchfield, Richard; Mitra, Pradip; Sullivan, William W.; Gleckler, Anthony D.; Strittmatter, Robert; Martin, Robert J.

    2014-08-01

    A linear mode photon counting focal plane array using HgCdTe mid-wave infrared (MWIR) cutoff electron initiated avalanche photodiodes (e-APDs) has been designed, fabricated, and characterized. The broad spectral range (0.4 to 4.3 μm) is unique among photon counters, making this a "first of its kind" system spanning the visible to the MWIR. The low excess noise [F(M)≈1] of the e-APDs allows for robust photon detection while operating at a stable linear avalanche gain in the range of 500-1000. The readout integrated circuit (ROIC) design included a very high gain-bandwidth product resistive transimpedance amplifier (3×1013 Ω-Hz) and a 4 ns output digital pulse width comparator. The ROIC had 16 high-bandwidth analogs and 16 low-voltage differential signaling digital outputs. The 2×8 array was integrated into an LN2 Dewar with a custom leadless chip carrier and daughter board design that preserved high-bandwidth analog and digital signal integrity. The 2×8 e-APD arrays were fabricated on 4.3 μm cutoff HgCdTe and operated at 84 K. The measured dark currents were approximately 1 pA at 13 V bias where the measured avalanche photodiode gain was 500. This translates to a predicted dark current induced dark count rate of less than 20 KHz. Single photon detection was achieved with a photon pulse signal-to-noise ratio of 13.7 above the amplifier noise floor. A photon detection efficiency of 50% was measured at a photon background limited false event rate of about 1 MHz. The measured jitter was in the range of 550-800 ps. The demonstrated minimum time between distinguishable events was less than 10 ns.

  12. Dislocations as a Noise Source in LWIR HgCdTe Photodiodes

    NASA Astrophysics Data System (ADS)

    Jóźwikowski, Krzysztof; Jóźwikowska, Alina; Martyniuk, Andrzej

    2016-02-01

    The effect of dislocation on the 1/f noise current in long-wavelength infrared (LWIR) reverse biased HgCdTe photodiodes working at liquid nitrogen (LN) temperature was analyzed theoretically by using a phenomenological model of dislocations as an additional Shockley-Read-Hall (SRH) generation-recombination (G-R) channel in heterostructure. Numerical analysis was involved to solve the set of transport equations in order to find a steady state values of physical parameters of the heterostructure. Next, the set of transport equations for fluctuations (TEFF) was formulated and solved to obtain the spectral densities (SD) of the fluctuations of electrical potential, quasi-Fermi levels, and temperature. The SD of mobility fluctuations, shot G-R noise, and thermal noise were also taken into account in TEFF. Additional expressions for SD of 1/f fluctuations of the G-R processes were derived. Numerical values of the SD of noise current were compared with the experimental results of Johnson et al. Theoretical analysis has shown that the dislocations increase the G-R processes and this way cause the growth of G-R dark current. Despite the fact that dislocations increase both shot G-R noise and 1/f G-R noise, the main cause of 1/f current noise in LN cooled LWIR photodiodes are fluctuations of the carriers mobility determined by 1/f fluctuations of relaxation times. As the noise current is proportional to the total diode current, growth of G-R dark current caused by dislocations leads to the growth of noise current.

  13. Hybrid artificial intelligence approach based on neural fuzzy inference model and metaheuristic optimization for flood susceptibilitgy modeling in a high-frequency tropical cyclone area using GIS

    NASA Astrophysics Data System (ADS)

    Tien Bui, Dieu; Pradhan, Biswajeet; Nampak, Haleh; Bui, Quang-Thanh; Tran, Quynh-An; Nguyen, Quoc-Phi

    2016-09-01

    This paper proposes a new artificial intelligence approach based on neural fuzzy inference system and metaheuristic optimization for flood susceptibility modeling, namely MONF. In the new approach, the neural fuzzy inference system was used to create an initial flood susceptibility model and then the model was optimized using two metaheuristic algorithms, Evolutionary Genetic and Particle Swarm Optimization. A high-frequency tropical cyclone area of the Tuong Duong district in Central Vietnam was used as a case study. First, a GIS database for the study area was constructed. The database that includes 76 historical flood inundated areas and ten flood influencing factors was used to develop and validate the proposed model. Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Receiver Operating Characteristic (ROC) curve, and area under the ROC curve (AUC) were used to assess the model performance and its prediction capability. Experimental results showed that the proposed model has high performance on both the training (RMSE = 0.306, MAE = 0.094, AUC = 0.962) and validation dataset (RMSE = 0.362, MAE = 0.130, AUC = 0.911). The usability of the proposed model was evaluated by comparing with those obtained from state-of-the art benchmark soft computing techniques such as J48 Decision Tree, Random Forest, Multi-layer Perceptron Neural Network, Support Vector Machine, and Adaptive Neuro Fuzzy Inference System. The results show that the proposed MONF model outperforms the above benchmark models; we conclude that the MONF model is a new alternative tool that should be used in flood susceptibility mapping. The result in this study is useful for planners and decision makers for sustainable management of flood-prone areas.

  14. 2 μm wavelength range InP-based type-II quantum well photodiodes heterogeneously integrated on silicon photonic integrated circuits.

    PubMed

    Wang, Ruijun; Sprengel, Stephan; Muneeb, Muhammad; Boehm, Gerhard; Baets, Roel; Amann, Markus-Christian; Roelkens, Gunther

    2015-10-01

    The heterogeneous integration of InP-based type-II quantum well photodiodes on silicon photonic integrated circuits for the 2 µm wavelength range is presented. A responsivity of 1.2 A/W at a wavelength of 2.32 µm and 0.6 A/W at 2.4 µm wavelength is demonstrated. The photodiodes have a dark current of 12 nA at -0.5 V at room temperature. The absorbing active region of the integrated photodiodes consists of six periods of a "W"-shaped quantum well, also allowing for laser integration on the same platform. PMID:26480194

  15. Performance characteristics of InGaAs/GaAs and GaAs/InGaAlAs coherently strained superlattice photodiodes

    NASA Technical Reports Server (NTRS)

    Das, Utpal; Zebda, Yousef; Bhattacharya, Pallab; Chin, Albert

    1987-01-01

    The properties of In(0.24)Ga(0.76)As/GaAs and GaAs/In(0.05)Ga(0.58)Al(0.37)As superlattice photodiodes grown by molecular beam epitaxy have been investigated. From the temporal response characteristics, deconvolved rise times about 60-100 ps are obtained. The measured responsivities of the photodiodes with dark currents of 5-10 nA at 10 V are about 0.4 A/W, which correspond to peak external quantum efficiencies of about 60 percent. These results indicate that very high performance photodiodes can be realized with strained layers.

  16. Analysis and design of a low-noise ROIC for hybrid InGaAs infrared FPA

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Huang, SongLei; Huang, ZhangCheng; Fang, Jiaxiong

    2011-08-01

    The noises of CMOS readout integrated circuit (ROIC) for hybrid focal plane array (FPA) may occupy a great part of total noise in conditions that a low resistance or large capacitor detector interfacing with CTIA input stage. A novel low noise low power preamplifier with shared current-mirrors bias is designed. It has a gain of more than 90dB, which makes enough inject efficiency and low detector bias offset. Besides, it has strong detector bias control, because the shared current-mirror copies the DC current of the amplifier and generates the bias control voltage. A pixel level Correlated Double Sample circuits is designed in order to suppress the reset KTC noise and 1/f noise from preamplifier. An experimental chip of 30μm pitch 32×32 array was fabricated in standard 0.5μm CMOS mixed signal process. A few experimental structures are designed to study the allocating of layout area for low noise designing. The ROIC is bonded to an existing back-illuminated 30μm pitch InGaAs photodiode array with indium bump fabrication. The test of both the ROIC chips and InGaAs focal plane array is shown in this paper, and the contrast of different structure is shown and analyzed.

  17. Smart hybrid rotary damper

    NASA Astrophysics Data System (ADS)

    Yang, C. S. Walter; DesRoches, Reginald

    2014-03-01

    This paper develops a smart hybrid rotary damper using a re-centering smart shape memory alloy (SMA) material as well as conventional energy-dissipating metallic plates that are easy to be replaced. The ends of the SMA and steel plates are inserted in the hinge. When the damper rotates, all the plates bend, providing energy dissipating and recentering characteristics. Such smart hybrid rotary dampers can be installed in structures to mitigate structural responses and to re-center automatically. The damaged energy-dissipating plates can be easily replaced promptly after an external excitation, reducing repair time and costs. An OpenSEES model of a smart hybrid rotary was established and calibrated to reproduce the realistic behavior measured from a full-scale experimental test. Furthermore, the seismic performance of a 3-story moment resisting model building with smart hybrid rotary dampers designed for downtown Los Angeles was also evaluated in the OpenSEES structural analysis software. Such a smart moment resisting frame exhibits perfect residual roof displacement, 0.006", extremely smaller than 18.04" for the conventional moment resisting frame subjected to a 2500 year return period ground motion for the downtown LA area (an amplified factor of 1.15 on Kobe earthquake). The smart hybrid rotary dampers are also applied into an eccentric braced steel frame, which combines a moment frame system and a bracing system. The results illustrate that adding smart hybrid rotaries in this braced system not only completely restores the building after an external excitation, but also significantly reduces peak interstory drifts.

  18. Low area 4-bit 5 MS/s flash-type digitizer for hybrid-pixel detectors - Design study in 180 nm and 40 nm CMOS

    NASA Astrophysics Data System (ADS)

    Otfinowski, Piotr; Grybos, Pawel

    2015-11-01

    We report on the design of a 4-bit flash ADC with dynamic offset correction dedicated to measurement systems based on a pixel architecture. The presented converter was manufactured in two CMOS technologies: widespread and economical 180 nm and modern 40 nm process. The designs are optimized for the lowest area occupancy resulting in chip areas of 160×55 μm2 and 35×25 μm2. The experimental results indicate integral nonlinearity of +0.35/-0.21 LSB and +0.28/-0.25 LSB and power consumption of 52 μW and 17 μW at 5 MS/s for the prototypes in 180 nm and 40 nm technologies respectively.

  19. Bounded hybrid superiority in an avian hybrid zone: effects of mate, diet, and habitat choice.

    PubMed

    Good, T P; Ellis, J C; Annett, C A; Pierotti, R

    2000-10-01

    There has been considerable debate in the study of hybrid zones as to whether hybrids may be superior to parental types within the area of contact (bounded hybrid superiority). In birds, naturally occurring hybridization is relatively common, and hybridization within this group always involves mate choice. If hybrids are superior, females choosing heterospecific mates should be expected to show higher fitness under the conditions prevalent in the hybrid zone. Hybrid superiority under these circumstances would reduce reinforcement and thereby help to maintain the hybrid zone. To examine this issue, we studied reproductive performances of hybrids and parental species of gulls (Larus occidentalis and Larus glaucescens) at two colonies within a linear hybrid zone along the west coast of the United States. This hybrid zone contains predominantly gulls of intermediate phenotype. Previous studies indicated that hybrids were superior to one or both parental types, but provided no data on possible mechanisms that underlie this hybrid superiority. Using a hybrid index designed specifically for these species, we identified to phenotype more than 300 individuals associated with nests, including both individual males and females within 73 pairs in the central portion of the hybrid zone and 74 pairs in the northern portion of the hybrid zone. There was little evidence of assortative mating, and what little there was resulted solely because of pairings within intergrades. In the central hybrid zone, females paired with hybrid males produced larger clutches and hatched and fledged more chicks compared with females paired to western gull males. This was a result of heavy predation on eggs in sand habitat, where male western gulls established territories. In contrast, many hybrid males established territories in vegetated cover that was less vulnerable to predation. In the northern part of the hybrid zone, clutch size did not differ among pair categories, however, there were

  20. Hybrid Solar GHP Simulator

    Energy Science and Technology Software Center (ESTSC)

    2012-12-11

    This project provides an easy-to-use, menu-driven, software tool for designing hybrid solar-geothermal heat pump systems (GHP) for both heating- and cooling-dominated buildings. No such design tool currently exists. In heating-dominated buildings, the design approach takes advantage of glazed solar collectors to effectively balance the annual thermal loads on the ground with renewable solar energy. In cooling-dominated climates, the design approach takes advantage of relatively low-cost, unglazed solar collectors as the heat rejecting component. The primarymore » benefit of hybrid GHPs is the reduced initial cost of the ground heat exchanger (GHX). Furthermore, solar thermal collectors can be used to balance the ground loads over the annual cycle, thus making the GHX fully sustainable; in heating-dominated buildings, the hybrid energy source (i.e., solar) is renewable, in contrast to a typical fossil fuel boiler or electric resistance as the hybrid component; in cooling-dominated buildings, use of unglazed solar collectors as a heat rejecter allows for passive heat rejection, in contrast to a cooling tower that consumes a significant amount of energy to operate, and hybrid GHPs can expand the market by allowing reduced GHX footprint in both heating- and cooling-dominated climates. The design tool allows for the straight-forward design of innovative GHP systems that currently pose a significant design challenge. The project lays the foundations for proper and reliable design of hybrid GHP systems, overcoming a series of difficult and cumbersome steps without the use of a system simulation approach, and without an automated optimization scheme. As new technologies and design concepts emerge, sophisticated design tools and methodologies must accompany them and be made usable for practitioners. Lack of reliable design tools results in reluctance of practitioners to implement more complex systems. A menu-driven software tool for the design of hybrid solar GHP systems

  1. Normal incidence spectrophotometer using high density transmission grating technology and highly efficiency silicon photodiodes for absolute solar EUV irradiance measurements

    NASA Technical Reports Server (NTRS)

    Ogawa, H. S.; Mcmullin, D.; Judge, D. L.; Korde, R.

    1992-01-01

    New developments in transmission grating and photodiode technology now make it possible to realize spectrometers in the extreme ultraviolet (EUV) spectral region (wavelengths less than 1000 A) which are expected to be virtually constant in their diffraction and detector properties. Time dependent effects associated with reflection gratings are eliminated through the use of free standing transmission gratings. These gratings together with recently developed and highly stable EUV photodiodes have been utilized to construct a highly stable normal incidence spectrophotometer to monitor the variability and absolute intensity of the solar 304 A line. Owing to its low weight and compactness, such a spectrometer will be a valuable tool for providing absolute solar irradiance throughout the EUV. This novel instrument will also be useful for cross-calibrating other EUV flight instruments and will be flown on a series of Hitchhiker Shuttle Flights and on SOHO. A preliminary version of this instrument has been fabricated and characterized, and the results are described.

  2. Wavelength-selective ultraviolet (Mg,Zn)O photodiodes: Tuning of parallel composition gradients with oxygen pressure

    NASA Astrophysics Data System (ADS)

    Zhang, Zhipeng; von Wenckstern, Holger; Lenzner, Jörg; Grundmann, Marius

    2016-06-01

    We report on ultraviolet photodiodes with integrated optical filter based on the wurtzite (Mg,Zn)O thin films. Tuning of the bandgap of filter and active layers was realized by employing a continuous composition spread approach relying on the ablation of a single segmented target in pulsed-laser deposition. Filter and active layers of the device were deposited on opposite sides of a sapphire substrate with nearly parallel compositional gradients. Ensure that for each sample position the bandgap of the filter layer blocking the high energy radiation is higher than that of the active layer. Different oxygen pressures during the two depositions runs. The absorption edge is tuned over 360 meV and the spectral bandwidth of photodiodes is typically 100 meV and as low as 50 meV.

  3. High performance CaS solar-blind ultraviolet photodiodes fabricated by seed-layer-assisted growth

    SciTech Connect

    He, Qing Lin; Lai, Ying Hoi; Sou, Iam Keong; Liu, Yi; Beltjens, Emeline; Qi, Jie

    2015-11-02

    CaS, with a direct bandgap of 5.38 eV, is expected to be a strong candidate as the active-layer of high performance solar-blind UV photodiodes that have important applications in both civilian and military sectors. Here, we report that a seed-layer-assisted growth approach via molecular beam epitaxy can result in high crystalline quality rocksalt CaS thin films on zincblende GaAs substrates. The Au/CaS/GaAs solar-blind photodiodes demonstrated , more than five orders in its visible rejection power, a photoresponse of 36.8 mA/w at zero bias and a corresponding quantum efficiency as high as 19% at 235 nm.

  4. The effect of temperature instability on the threshold sensitivity of photodetectors based on AIII-BV photodiodes

    NASA Astrophysics Data System (ADS)

    Aleksandrov, S. E.; Gavrilov, G. A.; Kapralov, A. A.; Sotnikova, G. Yu.

    2016-03-01

    The dependence of the sensitivity of photodetectors based on AIII-BV photodiodes on accidental variations of the temperature of its elements is analyzed. It is shown that the temperature drift of the bias level in input circuits of op-amps strongly contributes to the resulting photodetector noise up to frequencies on the order of 1 MHz. To reach the limiting sensitivities of the sensors, it is necessary to stabilize the temperature of not only the photodiode chip, but also the integrated circuit of the first amplifier stage. For most of applications, the required stabilization accuracy does not exceed ±0.1°C. As a result of the analysis, prototype high-sensitivity medium-wavelength (2-5 μm) sensors were developed that operate without forced cooling and have a detection threshold of tens of nanowatts at a detection bandwidth of 0-1 MHz.

  5. High performance CaS solar-blind ultraviolet photodiodes fabricated by seed-layer-assisted growth

    NASA Astrophysics Data System (ADS)

    He, Qing Lin; Lai, Ying Hoi; Liu, Yi; Beltjens, Emeline; Qi, Jie; Sou, Iam Keong

    2015-11-01

    CaS, with a direct bandgap of 5.38 eV, is expected to be a strong candidate as the active-layer of high performance solar-blind UV photodiodes that have important applications in both civilian and military sectors. Here, we report that a seed-layer-assisted growth approach via molecular beam epitaxy can result in high crystalline quality rocksalt CaS thin films on zincblende GaAs substrates. The Au/CaS/GaAs solar-blind photodiodes demonstrated , more than five orders in its visible rejection power, a photoresponse of 36.8 mA/w at zero bias and a corresponding quantum efficiency as high as 19% at 235 nm.

  6. Visible-blind and solar-blind ultraviolet photodiodes based on (InxGa1-x)2O3

    NASA Astrophysics Data System (ADS)

    Zhang, Zhipeng; von Wenckstern, Holger; Lenzner, Jörg; Lorenz, Michael; Grundmann, Marius

    2016-03-01

    UV and deep-UV selective photodiodes from visible-blind to solar-blind were realized based on a Si-doped (InxGa1-x)2O3 thin film with a monotonic lateral variation of 0.0035 < x < 0.83. Such layer was deposited by employing a continuous composition spread approach relying on the ablation of a single segmented target in pulsed-laser deposition. The photo response signal is provided from a metal-semiconductor-metal structure upon backside illumination. The absorption onset was tuned from 4.83 to 3.22 eV for increasing x. Higher responsivities were observed for photodiodes fabricated from indium-rich part of the sample, for which an internal gain mechanism could be identified.

  7. Investigation of trap-assisted tunneling current in InAs/(GaIn)Sb superlattice long-wavelength photodiodes

    NASA Astrophysics Data System (ADS)

    Yang, Q. K.; Fuchs, F.; Schmitz, J.; Pletschen, W.

    2002-12-01

    Trap centers with an energy level positioned 1/3 of the band gap below the effective conduction band edge are observed in the electroluminescence spectra of InAs/(GaIn)Sb superlattice photodiodes with a cutoff wavelength of 11 μm. The trap centers are recognized by simulating the low-temperature current-voltage characteristics of the diodes. Excellent quantitative agreement on both, the I-V characteristic and the differential resistance between the experimental data and the theoretical prediction is achieved. The quantitative simulation of the I-V characteristics shows, that the 77 K performance of InAs/(GaIn)Sb photodiodes is dominated by generation-recombination processes even at long wavelengths. Above 50 K, tunneling currents are not of importance.

  8. III-V strain layer superlattice based band engineered avalanche photodiodes (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Ghosh, Sid

    2015-08-01

    photodiodes and some of the recent results on the work being done at Raytheon on SWIR avalanche photodiodes.

  9. Development of novel technologies to enhance performance and reliability of III-Nitride avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Suvarna, Puneet Harischandra

    Solar-blind ultraviolet avalanche photodiodes are an enabling technology for applications in the fields of astronomy, communication, missile warning systems, biological agent detection and particle physics research. Avalanche photodiodes (APDs) are capable of detecting low-intensity light with high quantum efficiency and signal-to-noise ratio without the need for external amplification. The properties of III-N materials (GaN and AlGaN) are promising for UV photodetectors that are highly efficient, radiation-hard and capable of visible-blind or solar-blind operation without the need for external filters. However, the realization of reliable and high performance III-N APDs and imaging arrays has several technological challenges. The high price and lack of availability of bulk III-N substrates necessitates the growth of III-Ns on lattice mismatched substrates leading to a high density of dislocations in the material that can cause high leakage currents, noise and premature breakdown in APDs. The etched sidewalls of III-N APDs and high electric fields at contact edges are also detrimental to APD performance and reliability. In this work, novel technologies have been developed and implemented that address the issues of performance and reliability in III-Nitride based APDs. To address the issue of extended defects in the bulk of the material, a novel pulsed MOCVD process was developed for the growth of AlGaN. This process enables growth of high crystal quality AlxGa1-xN with excellent control over composition, doping and thickness. The process has also been adapted for the growth of high quality III-N materials on silicon substrate for devices such as high electron mobility transistors (HEMTs). A novel post-growth defect isolation technique is also discussed that can isolate the impact of conductive defects from devices. A new sidewall passivation technique using atomic layer deposition (ALD) of dielectric materials was developed for III-N APDs that is effective in

  10. The growth of CdHgTe on GaAs and fabrication of high-quality photodiodes

    SciTech Connect

    Smith, L.M.; Byrne, C.F.; Patel, D.; Knowles, P.; Thompson, J. ); Jenkin, G.T. ); Nguyen Duy, T.; Durand, A.; Bourdillot, M. )

    1990-03-01

    The use of metal organic vapor phase epitaxy (MOVPE) for the growth of device quality CdHgTe (MCT) on GaAs has been studied extensively. This is the first report of diode formation by mercury diffusion in the MOVPE grown material. It is also the first report of medium-wavelength infrared (MWIR) photodiodes made in the material. The effect of altering the cadmium to tellurium alkyl ratios on the growth of a CdTe buffer on (100) and (111)GaAs was investigated. For every alkyl ratio used, it was possible to grow (111) or (100)CdTe on (100)GaAs. (100)CdTe/(100)GaAs samples exhibited very sharp, well-defined photoluminescence spectra and x-ray rocking curve full width half-maximum (FWHM) peaks of {lt}90 arc s were found for layers of 6--10 {mu}m thick. Generally the (111)CdTe/(111)GaAs layers were dominated by twins, but the growth of untwinned (111)CdTe and MCT is reported. CdTe, high {ital x} MCT, and combinations of CdTe and HgTe layers were used as buffers for (100)MCT growth to reduce the hillock density. The combinations of CdTe and HgTe layers gave rise to the lowest hillock density (at best 30--100/cm{sup 2}) over a large area (25{times}25 mm{sup 2}). FWHMs of 80--90 arc s are routinely achieved for (100)MCT layers. Linear diode arrays have been fabricated with 77 K {ital R}{sub 0}{ital A} values typically of 3{times}10{sup 3} {Omega} cm{sup 2} for 7.5 {mu}m cutoff. The detectivity of a 5.5 {mu}m cutoff diode was 1.5{times}10{sup 11} cm Hz{sup 1/2} W{sup {minus}1} at 77 K, and 1.3{times}10{sup 10} cm Hz{sup 1/2} W{sup {minus}1} at 193 K. This is comparable to the performance obtained with the best traveling heater method devices.

  11. A new type of thermal-neutron detector based on ZnS(Ag)/LiF scintillator and avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Marin, V. N.; Sadykov, R. A.; Trunov, D. N.; Litvin, V. S.; Aksenov, S. N.; Stolyarov, A. A.

    2015-09-01

    A high-efficiency thermal-neutron detector based on ZnS(Ag)/LiF scintillator is described, which employs a new technique of signal pick-up with the aid of a light guide and avalanche photodiodes instead of optical fibers and photomultipliers. Results of tests on the RADEX pulsed neutron source are presented, in which neutron diffraction patterns of test objects have been obtained.

  12. The Reliability Of Planar InGaAs/InP PIN Photodiodes With Organic Coatings For Use In Low Cost Receivers

    NASA Astrophysics Data System (ADS)

    Sutherland, Robert R.; Stokoe, J. C.; Skrimshire, Christopher P.; MacDonald, Brian M.; Sloan, Donald F.

    1990-01-01

    Low-cost optoelectronic components in non-hermetic packages are now required for use in the local loop, and these components will be subject to humidity-induced failure mechanisms. The results presented in this paper show that it is possible to provide some protection for the photodiode against the effects of humidity by means of an organic coating. Photodiodes with three different organic coatings were tested at 85C/85% relative humidity, and all survived longerthan uncoated control photodiodes. One of the coatings was superior to the other two, and photodiodes with this coating may have adequate reliability for some local loop applications. The temperature and humidity acceleration factors for uncoated photodiodes were determined. The temperature acceleration factor was found to be low (equivalent to an activation energy of 0.2eV, instead of the more usual 0.6eV). Failure analysis of failed photodiodes, which included Auger analysis of corrosion products, showed that failure was due to oxidation of the InP surface.

  13. High-optical-power handling InGaAs photodiodes and balanced receivers for high-spurious free dynamic range (SFDR) analog photonic links

    NASA Astrophysics Data System (ADS)

    Joshi, Abhay M.; Wang, Xinde; Mohr, Dan; Becker, Donald; Patil, Ravikiran

    2004-08-01

    We have developed 20 mA or higher photocurrent handling InGaAs photodiodes with 20 GHz bandwidth, and 10 mA or higher photocurrent handling InGaAs photodiodes with >40 GHz bandwidth. These photodiodes have been thoroughly tested for reliability including Bellcore GR 468 standard and are built to ISO 9001:2000 Quality Management System. These Dual-depletion InGaAs/InP photodiodes are surface illuminated and yet handle such large photocurrent due to advanced band-gap engineering. They have broad wavelength coverage from 800 nm to 1700 nm, and thus can be used at several wavelengths such as 850 nm, 1064 nm, 1310 nm, 1550 nm, and 1620 nm. Furthermore, they exhibit very low Polarization Dependence Loss of 0.05dB typical to 0.1dB maximum. Using above high current handling photodiodes, we have developed classical Push-Pull pair balanced photoreceivers for the 2 to 18 GHz EW system. These balanced photoreceivers boost the Spurious Free Dynamic Range (SFDR) by almost 3 dB by eliminating the laser RIN noise. Future research calls for designing an Avalanche Photodiode Balanced Pair to boost the SFDR even further by additional 3 dB. These devices are a key enabling technology in meeting the SFDR requirements for several DoD systems.

  14. Tunable Ultraviolet Photoresponse in Solution-Processed p-n Junction Photodiodes Based on Transition-Metal Oxides.

    PubMed

    Xie, Ting; Liu, Guannan; Wen, Baomei; Ha, Jong Y; Nguyen, Nhan V; Motayed, Abhishek; Debnath, Ratan

    2015-05-13

    Solution-processed p-n heterojunction photodiodes have been fabricated based on transition-metal oxides in which NiO and ternary Zn(1-x)Mg(x)O (x = 0-0.1) have been employed as p-type and n-type semiconductors, respectively. Composition-related structural, electrical, and optical properties are also investigated for all the films. It has been observed that the bandgap of Zn(1-x)Mg(x)O films can be tuned between 3.24 and 3.49 eV by increasing Mg content. The fabricated highly visible-blind p-n junction photodiodes show an excellent rectification ratio along with good photoresponse and quantum efficiency under ultraviolet (UV) illumination. With an applied reverse bias of 1 V and depending on the value of x, the maximum responsivity of the devices varies between 0.22 and 0.4 A/W and the detectivity varies between 0.17 × 10(12) and 2.2 × 10(12) cm (Hz)(1/2)/W. The photodetectors show an excellent UV-to-visible rejection ratio. Compositional nonuniformity has been observed locally in the alloyed films with x = 0.1, which is manifested in photoresponse and X-ray analysis data. This paper demonstrates simple solution-processed, low cost, band tunable photodiodes with excellent figures of merit operated under low bias. PMID:25898025

  15. X-ray spectroscopy in mammography with a silicon PIN photodiode with application to the measurement of tube voltage

    SciTech Connect

    Kuenzel, Roseli; Herdade, Silvio Bruni; Terini, Ricardo Andrade; Costa, Paulo Roberto

    2004-11-01

    In this work a silicon PIN photodiode was employed in mammographic x-ray spectroscopy under clinical and nonclinical conditions. Measurements have been performed at a constant potential tungsten anode tube, adapted in this work with molybdenum filters to produce a beam like that used in mammography, and at a clinical equipment with a molybdenum anode tube by using an additional aluminum filtration. The corrected x-ray spectra were in full agreement with those generated by theoretical models published in the literature and agree well with those measured with a CdZnTe detector for tube voltages less than 30 kV. The half value layer and the relative exposure values calculated from the corrected silicon PIN photodiode spectra were in agreement with those measured with an ionization chamber. These results indicate that a silicon PIN photodiode are very suitable for mammographic x-ray spectroscopy. As an application, the voltage (kV) applied to mammographic x-ray equipment has been measured through the evaluation of the spectra high energy cut off. Uncertainties evaluated for the voltage values calculated from the measured spectra are less than 0.13% for voltages in the range 20-35 kV. The low uncertainties associated with the obtained results in this work point out that the method employed can be accurately used for calibration of noninvasive mammographic kVp meters.

  16. Full well capacity and quantum efficiency optimization for small size backside illuminated CMOS image pixels with a new photodiode structure

    NASA Astrophysics Data System (ADS)

    Yu, Sun; Ping, Zhang; Jiangtao, Xu; Zhiyuan, Gao; Chao, Xu

    2012-12-01

    To improve the full well capacity (FWC) of a small size backside illuminated (BSI) CMOS image sensor (CIS), the effect of photodiode capacitance (CPD) on FWC is studied, and a reformed pinned photodiode (PPD) structure is proposed. Two procedures are implemented for the optimization. The first is to form a varying doping concentration and depth stretched new N region, which is implemented by an additional higher-energy and lower-dose N type implant beneath the original N region. The FWC of this structure is increased by extending the side wall junctions in the substrate. Secondly, in order to help the enlarged well capacity achieve full depletion, two step P-type implants with different implant energies are introduced to form a P-type insertion region in the interior of the stretched N region. This vertical inserted P region guarantees that the proposed new PD structure achieves full depletion in the reset period. The simulation results show that the FWC can be improved from 1289e- to 6390e-, and this improvement does not sacrifice any image lag performance. Additionally, quantum efficiency (QE) is enhanced in the full wavelength range, especially 6.3% at 520 nm wavelength. This technique can not only be used in such BSI structures, but also adopted in an FSI pixel with any photodiode-type readout scheme.

  17. Numerical Examination of Silicon Avalanche Photodiodes Operated in Charge Storage Mode

    NASA Technical Reports Server (NTRS)

    Parks, Joseph W., Jr.; Brennan, Kevin F.

    1998-01-01

    The behavior of silicon-based avalanche photodiodes (APD's) operated in the charge storage mode is examined. In the charge storage mode, the diodes are periodically biased to a sub-breakdown voltage and then open-circuited. During this integration period, photo-excited and thermally generated carriers are accumulated within the structure. The dynamics of this accumulation and its effects upon the avalanching of the diode warrants a detailed, fully numerical analysis. The salient features of this investigation include device sensitivity to the input photo-current including the self-quenching effect of the diode and its limitations in sensing low light levels, the dependence of the response on the bulk lifetime and hence on the generation current within the device, the initial gain, transient response, dependence of the device uniformity upon performance, and the quantity of storable charge within the device. To achieve these tasks our device simulator, STEBS-2D, was utilized. A modified current-controlled boundary condition is employed which allows for the simulation of the isolated diode after the initial reset bias has been applied. With this boundary condition, it is possible to establish a steady-state voltage on the ohmic contact and then effectively remove the device from the external circuit while still including effects from surface recombination, trapped surface charge, and leakage current from the read-out electronics.

  18. Slot clock recovery in optical PPM communication systems with avalanche photodiode photodetectors

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic M.; Sun, Xiaoli

    1989-01-01

    Slot timing recovery in a direct-detection optical PPM communication system can be achieved by processing the photodetector output waveform with a nonlinear device whose output forms the input to a phase-locked loop. The choice of a simple transition detector as the nonlinearity is shown to give satisfactory synchronization performance. The rms phase error of the recovered slot clock and the effect of slot timing jitter on the bit error probability were directly measured. The experimental system consisted of an AlGaAs laser diode (wavelength = 834 nm) and a silicon avalanche photodiode photodetector. The system used Q = 4 PPM signaling and operated at a source data rate of 25 Mbits/s. The mathematical model developed to compute the rms phase error of the recovered clock is shown to be in good agreement with results of actual measurements of phase errors. The use of the recovered slot clock in the receiver resulted in no significant degradation in receiver sensitivity compared to a system with perfect slot timing. The system achieved a bit error probability of 10 to the -6th at a received optical signal energy of 55 detected photons per information bit.

  19. Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector

    NASA Technical Reports Server (NTRS)

    Huntington, Andrew

    2013-01-01

    The purpose of this program was to develop single-photon-sensitive short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) avalanche photodiode (APD) receivers based on linear-mode HgCdTe APDs, for application by NASA in light detection and ranging (lidar) sensors. Linear-mode photon-counting APDs are desired for lidar because they have a shorter pixel dead time than Geiger APDs, and can detect sequential pulse returns from multiple objects that are closely spaced in range. Linear-mode APDs can also measure photon number, which Geiger APDs cannot, adding an extra dimension to lidar scene data for multi-photon returns. High-gain APDs with low multiplication noise are required for efficient linear-mode detection of single photons because of APD gain statistics -- a low-excess-noise APD will generate detectible current pulses from single photon input at a much higher rate of occurrence than will a noisy APD operated at the same average gain. MWIR and LWIR electron-avalanche HgCdTe APDs have been shown to operate in linear mode at high average avalanche gain (M > 1000) without excess multiplication noise (F = 1), and are therefore very good candidates for linear-mode photon counting. However, detectors fashioned from these narrow-bandgap alloys require aggressive cooling to control thermal dark current. Wider-bandgap SWIR HgCdTe APDs were investigated in this program as a strategy to reduce detector cooling requirements.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  1. Multihit mode direct-detection laser radar system using a Geiger-mode avalanche photodiode.

    PubMed

    Oh, Min Seok; Kong, Hong Jin; Kim, Tae Hoon; Hong, Keun Ho; Kim, Byung Wook; Park, Dong Jo

    2010-03-01

    In this paper, a direct-detection laser radar system that uses a Geiger-mode avalanche photodiode (GAPD) of relatively short dead time (45 ns) is described. A passively Q-switched microchip laser is used as a laser source and a compact peripheral component interconnect system, which includes a time-to-digital converter (TDC), is set up for fast signal processing. With both the GAPD and the TDC functioning multistop acquisition, the system operates in a multihit mode. The software for the three-dimensional visualization and an algorithm for the removal of noise are developed. It is shown that the single-shot precision of the system is approximately 10 cm (sigma) and the precision is improved by increasing the number of laser pulses to be averaged so that the precision of approximately 1 cm (sigma) was acquired with more than 150 laser pulses scattered from the target. The accuracy of the system is measured to be 12 cm when the energy of the emitted laser pulse varies with a factor of 7. PMID:20370163

  2. Photodiode Based on CdO Thin Films as Electron Transport Layer

    NASA Astrophysics Data System (ADS)

    Soylu, M.; Kader, H. S.

    2016-08-01

    Cadmium oxide (CdO) thin films were synthesized by the sol-gel method. The films were analyzed by means of XRD, AFM, and UV/Vis spectrophotometry. X-ray diffraction patterns confirm that the films are formed from CdO with cubic crystal structure and consist of nano-particles. The energy gap of the prepared film was found to be 2.29 eV. The current-voltage (I-V) characteristics of the CdO/p-Si heterojunction were examined in the dark and under different illumination intensities. The heterojunction showed high rectifying behavior and a strong photoresponse. Main electrical parameters of the photodiode such as series and shunt resistances (R s and R sh), saturation current I 0, and photocurrent I ph, were extracted considering a single diode equivalent circuit of a photovoltaic cell. Results indicate that the application of CdO thin films as an electron transport layer on p-Si acts as a photodetector in the field of the UV/visible.

  3. A comparison of avalanche photodiode and photomultiplier tube detectors for flow cytometry

    NASA Astrophysics Data System (ADS)

    Lawrence, William G.; Varadi, Gyula; Entine, Gerald; Podniesinski, Edward; Wallace, Paul K.

    2008-02-01

    Commercial flow cytometers use photomultiplier tubes (PMTs) for fluorescence detection. These detectors have high linear gain and broad dynamic range, but have limited sensitivity in the red and near infrared spectral regions. We present a comparison of avalanche photodiodes (APDs) and PMTs as detectors in flow cytometry instruments, and demonstrate improved sensitivity and resolution in the red and near infrared spectral regions using the APD. The relative performance of the PMT and APD were evaluated by simultaneously measuring the mean fluorescence intensity and coefficient of variation for emission from light emitting diode pulses, flow cytometry test beads, and fluorescently labeled cells. The relative signal to noise performance of the APD and PMT was evaluated over the 500 nm to 1050 nm wavelength range using pulsed light emitting diode light sources. While APDs have higher quantum efficiency but lower internal gain than PMTs, with appropriate external amplification the APD has signal to noise response that is comparable to PMTs in the 500 nm to 650 nm range and improved response in the 650 nm to 850 nm range The data demonstrates that the APD had performance comparable to the PMT in the spectral region between 500 to 650 nm and improved performance in the range of 650 to 1000 nm, where the PMT performance is quite poor. CD4 positive lymphocyte populations were easily identified in normal human blood both by APD and PMT using phycoerythrin labeled antibodies. In contrast, only the APD detector could resolve CD4 positive populations using 800 nm Quantum dot labeled antibodies.

  4. High-accuracy and cost-effective photodiode spectral response measurement system

    NASA Astrophysics Data System (ADS)

    Chang, Gao-Wei; Liao, Chia-Cheng; Yeh, Zong-Mu

    2007-02-01

    With the rapid growth of optoelectronics technologies, photodiodes (PDs) has been widely used in optical measurement systems, color measurement and analysis systems, etc. To meet most of the measurement requirements, the determination of PD spectral responses is very important. The goal of this paper is to develop a high-accuracy and cost-effective spectral response measurement system for PDs. In this paper, the proposed system contains a grating-based spectral filtering module, an amplifier module, and a digital-signal-processing (DSP) based platform. In the spectral filtering module, a single-grating monochromator based on a Czerny-Turner configuration is first analyzed and simulated, and then the experiments are conducted to check if the measurement accuracy is satisfactory. In the measurement system, optoelectronic signals from the PD under test are acquired from the amplifier module and the DSP-based platform is developed to communicate and manipulate the measured data. Through comparison with the measurement data from a commercially available system, it is found that our approach gives quite satisfactory results.

  5. Impact ionization in AlxGa1-xAsySb1-y avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Grzesik, M.; Donnelly, J.; Duerr, E.; Manfra, M.; Diagne, M.; Bailey, R.; Turner, G.; Goodhue, W.

    2014-04-01

    Avalanche photodiodes (APDs) have been fabricated in order to determine the impact ionization coefficients of electrons (α) and holes (β) in AlxGa1-xAsySb1-y lattice matched to GaSb for three alloy compositions: (x = 0.40, y = 0.035), (x = 0.55, y = 0.045), and (x = 0. 65, y = 0.054). The impact ionization coefficients were calculated from photomultiplication measurements made on specially designed APDs, which allowed for both pure electron and pure hole injection in the same device. Photo-multiplication measurements were made at temperatures ranging from 77 K to 300 K for all three alloys. A quasi-physical model with an explicit temperature dependence was used to express the impact ionization coefficients as a function of electric-field strength and temperature. For all three alloys, it was found that α < β at any given temperature. In addition, the values of the impact ionization coefficients were found to decrease as the aluminum concentration of the AlGaAsSb alloy was increased. A value between 1.2 and 4.0 was found for β/α, which is dependent on temperature, alloy composition, and electric-field strength.

  6. High-speed bridge circuit for InGaAs avalanche photodiode single-photon detector

    NASA Astrophysics Data System (ADS)

    Hashimoto, Hirofumi; Tomita, Akihisa; Okamoto, Atsushi

    2014-02-01

    Because of low power consumption and small footprint, avalanche photodiodes (APD) have been commonly applied to photon detection. Recently, high speed quantum communication has been demonstrated for high bit-rate quantum key distribution. For the high speed quantum communication, photon detectors should operate at GHz-clock frequencies. We propose balanced detection circuits for GHz-clock operation of InGaAs-APD photon detectors. The balanced single photon detector operates with sinusoidal wave gating. The sinusoidal wave appearing in the output is removed by the subtraction from APD signal without sharp band-elimination filters. Omission of the sharp filters removes the constraint on the operating frequency of the single photon detector. We present two designs, one works with two identical APDs, the other with one APD and a low-pass filter. The sinusoidal gating enables to eliminate the gating noise even with the simple configuration of the latter design. We demonstrated the balanced single photon detector operating with 1.020GHz clock at 233 K, 193 K, and 186.5 K. The dark count probability was 4.0 x 10-4 counts/pulse with the quantum efficiency of 10% at 233K, and 1.6 x 10-4 counts/pulse at 186.5 K. These results were obtained with easily available APDs (NR8300FP-C.C, RENESASS) originally developed for optical time-domain reflectmeters.

  7. Fast single photon avalanche photodiode-based time-resolved diffuse optical tomography scanner

    PubMed Central

    Mu, Ying; Niedre, Mark

    2015-01-01

    Resolution in diffuse optical tomography (DOT) is a persistent problem and is primarily limited by high degree of light scatter in biological tissue. We showed previously that the reduction in photon scatter between a source and detector pair at early time points following a laser pulse in time-resolved DOT is highly dependent on the temporal response of the instrument. To this end, we developed a new single-photon avalanche photodiode (SPAD) based time-resolved DOT scanner. This instrument uses an array of fast SPADs, a femto-second Titanium Sapphire laser and single photon counting electronics. In combination, the overall instrument temporal impulse response function width was 59 ps. In this paper, we report the design of this instrument and validate its operation in symmetrical and irregularly shaped optical phantoms of approximately small animal size. We were able to accurately reconstruct the size and position of up to 4 absorbing inclusions, with increasing image quality at earlier time windows. We attribute these results primarily to the rapid response time of our instrument. These data illustrate the potential utility of fast SPAD detectors in time-resolved DOT. PMID:26417526

  8. Progress in the use of avalanche photodiodes for readout for calorimeters

    SciTech Connect

    Fenker, H.; Morgan, K.; Regan, T.

    1991-09-01

    During the past year the Superconducting Super Collider Tracking Group has progressed from acquisition of its first avalanche photodiode (APD) to installation of a 96-channel array of the devices. The work was motivated by the desire to learn how to use APDs as the sensitive elements in a fiber tracking detector, moderated by the presence of limited resources and the absence of activity within groups outside the SSC Laboratory on such a project. We chose, therefore, to team up with an ongoing research effort which intended to evaluate both pre-shower and shower-maximum detectors and various means of sensing the light produced. The pre-shower detector is made of layers of scintillating fibers similar to a fiber tracker. The shower-maximum detector uses optical fibers to transmit the light from scintillating plates to the readout devices. Our contribution has been to develop the APD array for use in this test from concept to operation. Currently, the equipment is installed in Fermilab's MP beamline awaiting delivery to the final 36 APDs and exposure to the beam. 9 refs., 18 figs.

  9. Thin active region, type II superlattice photodiode arrays: Single-pixel and focal plane array characterization

    NASA Astrophysics Data System (ADS)

    Little, J. W.; Svensson, S. P.; Beck, W. A.; Goldberg, A. C.; Kennerly, S. W.; Hongsmatip, T.; Winn, M.; Uppal, P.

    2007-02-01

    We have measured the radiometric properties of two midwave infrared photodiode arrays (320×256pixel2 format) fabricated from the same wafer comprising a thin (0.24μm), not intentionally doped InAs /GaSb superlattice between a p-doped GaSb layer and a n-doped InAs layer. One of the arrays was indium bump bonded to a silicon fanout chip to allow for the measurement of properties of individual pixels, and one was bonded to a readout integrated circuit to enable array-scale measurements and infrared imaging. The superlattice layer is thin enough that it is fully depleted at zero bias, and the collection efficiency of photogenerated carriers in the intrinsic region is close to unity. This simplifies the interpretation of photocurrent data as compared with previous measurements made on thick superlattices with complex doping profiles. Superlattice absorption coefficient curves, obtained from measurements of the external quantum efficiency using two different assumptions for optical coupling into the chip, bracket values calculated using an eight-band k •p model. Measurements of the quantum efficiency map of the focal plane array were in good agreement with the single-pixel measurements. Imagery obtained with this focal plane array demonstrates the high uniformity and crystal quality of the type II superlattice material.

  10. Simultaneous determination of five aluminum lake dyes in chewing gum by HPLC with photodiode array detection.

    PubMed

    Yang, Yi; Yin, Jie; Shao, Bing

    2011-09-01

    A simple and rapid method has been developed and validated for the determination of five food aluminum lake dyes (Tartrazine Al lake, Sunset Yellow Al lake, Ponceau 4R Al lake, Allura Red Al lake and Brilliant Blue Al lake) in chewing gum. The dye portions of the target aluminum lakes were simultaneous extracted with 0.25 M NaOH and cleaned up by liquid-liquid extraction with dichloromethane, followed by further purification using Oasis WAX solid-phase extraction (SPE) cartridges. Analytes were separated by HPLC using an Inertsil ® ODS-3 column coupled to a photodiode array detector. The amounts of the aluminum lake dyes were finally quantified and indicated as their dye portions using corresponding calibration curves over ranges of 0.5 to 50 µg ml(-1), with correlation coefficients >0.9999. Recoveries of the dye parts in aluminum lake dyes (spiked at levels of 1, 5, 25 µg g(-1)) ranged from 72.5 to 116.4%, with relative standard deviations between 0.9 and 6.5%. Limits of detection and limits of quantification for all analytes were 0.15 and 0.50 µg g(-1), respectively. This method was successfully applied in real samples of chewing gum. PMID:21707267

  11. Supercritical fluid chromatography with photodiode array detection for pesticide analysis in papaya and avocado samples.

    PubMed

    Pano-Farias, Norma S; Ceballos-Magaña, Silvia G; Gonzalez, Jorge; Jurado, José M; Muñiz-Valencia, Roberto

    2015-04-01

    To improve the analysis of pesticides in complex food matrices with economic importance, alternative chromatographic techniques, such as supercritical fluid chromatography, can be used. Supercritical fluid chromatography has barely been applied for pesticide analysis in food matrices. In this paper, an analytical method using supercritical fluid chromatography coupled to a photodiode array detection has been established for the first time for the quantification of pesticides in papaya and avocado. The extraction of methyl parathion, atrazine, ametryn, carbofuran, and carbaryl was performed through the quick, easy, cheap, effective, rugged, and safe methodology. The method was validated using papaya and avocado samples. For papaya, the correlation coefficient values were higher than 0.99; limits of detection and quantification ranged from 130-380 and 220-640 μg/kg, respectively; recovery values ranged from 72.8-94.6%; precision was lower than 3%. For avocado, limit of detection values were ˂450 μg/kg; precision was lower than 11%; recoveries ranged from 50.0-94.2%. Method feasibility was tested for lime, banana, mango, and melon samples. Our results demonstrate that the proposed method is applicable to methyl parathion, atrazine, ametryn, and carbaryl, toxics pesticides used worldwide. The methodology presented in this work could be applicable to other fruits. PMID:25641906

  12. Solution-processed colloidal quantum dot photodiodes for low-cost SWIR imaging

    NASA Astrophysics Data System (ADS)

    Klem, Ethan J. D.; Lewis, Jay; Gregory, Christopher; Cunningham, Garry; Temple, Dorota

    2012-06-01

    While InGaAs-based focal plane arrays (FPAs) provide excellent detectivity and low noise for SWIR imaging applications, wider scale adoption of systems capable of working in this spectral range is limited by high costs, limited spectral response, and costly integration with Si ROIC devices. RTI has demonstrated a novel photodiode technology based on IR-absorbing solution-processed PbS colloidal quantum dots (CQD) that can overcome these limitations of InGaAs FPAs. We have fabricated devices with quantum efficiencies exceeding 50%, and detectivities that are competitive with that of InGaAs. Dark currents of ~2 nA/cm2 were measured at temperatures compatible with solid state coolers. Additionally, by processing these devices entirely at room temperature we find them to be compatible with monolithic integration onto readout ICs, thereby removing any limitation on device size. We will show early efforts towards demonstrating a direct integration of this sensor technology onto a Si ROIC IC and describe a path towards fabricating sensors sensitive from the visible to 2200 nm at a cost comparable to that of CMOS based devices. This combination of high performance, dramatic cost reduction, and multispectral sensitivity is ideally suited to expand the use of SWIR imaging in current applications, as well as to address applications which require a multispectral sensitivity not met by existing technologies.

  13. 25 Gbps 850 nm photodiode for emerging 100 Gb ethernet applications

    NASA Astrophysics Data System (ADS)

    Joshi, Abhay; Rue, Jim; Becker, Don; Datta, Shubhashish; McFaul, Will

    2011-06-01

    The IEEE Std 802.3ba-2010 for 40 Gb and 100 Gb Ethernet was released in July, 2010. This standard will continue to evolve over the next several years. Two of the challenging transmit/receive architectures contained in this standard are the 100GBASE-LR4 (<10 km range) and 100GBASE-ER4 (<40 km range). Although presently envisioned for 1310 nm optical wavelengths, both of these 4 lane, 25.78 GBaud formats may be adopted for the impending 850 nm short reach optical backplane market, whose range is below 150 m. Driven by major computer server companies, such as IBM, HP and Oracle, the 850 nm Active Optical Cable (AOC) market is presently undergoing an increase of serial rates up to 25 Gbaud to enhance backplane interconnectivity. With AOCs up to 16 channels, the potential for up to 400 Gbps backhaul composite data rates will soon be possible. We report a 25 Gbps photodiode with quantum efficiency ~ 0.6 at 850 nm. This InGaAs/InP device was optimized for high quantum efficiency at 850 nm. When pigtailed with multimode fiber and integrated with an application-specific RF amplifier, the resultant photoreceiver will provide multiple functionalities for these 100 Gb Ethernet markets.

  14. Super-Junction PIN Photodiode to Integrate Optoelectronic Integrated Circuits in Standard Technologies: A Numerical Study

    NASA Astrophysics Data System (ADS)

    Roig, Jaume; Stefanov, Evgueniy; Morancho, Frédéric

    2007-07-01

    The use of super-junction (SJ) techniques in PIN photodiodes is proposed in this letter for the first time with the objective to assist the optoelectronic integrated circuits (OEICs) implementation in complementary metal oxide semiconductor (CMOS), bipolar CMOS (BiCMOS) and bipolar-CMOS-double diffused MOS (BCD) technologies. Its technological viability is also discussed to make it credible as an alternative to other OEICs approaches. Numerical simulation of realistic SJ-PIN devices, widely used in high power electronics, demonstrates the possibility to integrate high-performance CMOS-based OEICs in epitaxial layers with doping concentrations above 1× 1015 cm-3. The induced lateral depletion at low reverse biased voltage, assisted by the alternated N and P-doped pillars, allows high-speed transient response in SJ-PIN detecting wavelengths between 400 and 800 nm. Moreover, other important parameters as the responsivity and the dark current are not degraded in respect to the conventional PIN (C-PIN) structures.

  15. Plasmonic field confinement for separate absorption-multiplication in InGaAs nanopillar avalanche photodiodes.

    PubMed

    Farrell, Alan C; Senanayake, Pradeep; Hung, Chung-Hong; El-Howayek, Georges; Rajagopal, Abhejit; Currie, Marc; Hayat, Majeed M; Huffaker, Diana L

    2015-01-01

    Avalanche photodiodes (APDs) are essential components in quantum key distribution systems and active imaging systems requiring both ultrafast response time to measure photon time of flight and high gain to detect low photon flux. The internal gain of an APD can improve system signal-to-noise ratio (SNR). Excess noise is typically kept low through the selection of material with intrinsically low excess noise, using separate-absorption-multiplication (SAM) heterostructures, or taking advantage of the dead-space effect using thin multiplication regions. In this work we demonstrate the first measurement of excess noise and gain-bandwidth product in III-V nanopillars exhibiting substantially lower excess noise factors compared to bulk and gain-bandwidth products greater than 200 GHz. The nanopillar optical antenna avalanche detector (NOAAD) architecture is utilized for spatially separating the absorption region from the avalanche region via the NOA resulting in single carrier injection without the use of a traditional SAM heterostructure. PMID:26627932

  16. Performance Analysis of OCDMA Based on AND Detection in FTTH Access Network Using PIN & APD Photodiodes

    NASA Astrophysics Data System (ADS)

    Aldouri, Muthana; Aljunid, S. A.; Ahmad, R. Badlishah; Fadhil, Hilal A.

    2011-06-01

    In order to comprise between PIN photo detector and avalanche photodiodes in a system used double weight (DW) code to be a performance of the optical spectrum CDMA in FTTH network with point-to-multi-point (P2MP) application. The performance of PIN against APD is compared through simulation by using opt system software version 7. In this paper we used two networks designed as follows one used PIN photo detector and the second using APD photo diode, both two system using with and without erbium doped fiber amplifier (EDFA). It is found that APD photo diode in this system is better than PIN photo detector for all simulation results. The conversion used a Mach-Zehnder interferometer (MZI) wavelength converter. Also we are study, the proposing a detection scheme known as AND subtraction detection technique implemented with fiber Bragg Grating (FBG) act as encoder and decoder. This FBG is used to encode and decode the spectral amplitude coding namely double weight (DW) code in Optical Code Division Multiple Access (OCDMA). The performances are characterized through bit error rate (BER) and bit rate (BR) also the received power at various bit rate.

  17. Ultrafast dual-drifting layer uni-traveling carrier photodiode with high saturation current.

    PubMed

    Li, Jin; Xiong, Bing; Luo, Yi; Sun, Changzheng; Wang, Jian; Hao, Zhibiao; Han, Yanjun; Wang, Lai; Li, Hongtao

    2016-04-18

    A novel backside-illuminated mesa-structure dual-drifting layer (DDL) uni-traveling-carrier photodiode (UTC-PD) is reported to demonstrate high-power performance at sub-THz frequencies. The DDL structure consists of a velocity overshoot layer and a velocity saturation layer, formed by inserting a 20 nm p-type cliff layer into the thick depletion region. In the overshoot layer, photo-generated electrons drift at overshoot velocity under the carefully designed electric field profile, thus resulting in a short electron transit time. The saturation layer serves as a voltage sacrificing layer to enable high bias voltage operation, which leads to alleviated load voltage swing effect, as well as improved saturation performance. Our DDL UTC-PD exhibits a 3-dB bandwidth of 106 GHz with a responsivity of 0.17 A/W under a wide bias voltage range from 4 to 8 V. The photocurrent reaches up to 28 mA, corresponding to an output power of 7.3 dBm at 105 GHz. PMID:27137280

  18. Design of broadband and high-output power uni-traveling-carrier photodiodes

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Zhang, Xiupu; Zhang, Rong

    2016-04-01

    In this paper, the bandwidth and saturation current of uni-traveling-carrier photodiode (UTC-PD) is investigated by using physics-based modeling. To further improve the performance, novel device structures are proposed. On the one hand, graded bandgap structure is employed in the absorption layer. It is shown that similar to the effect of graded doping method, the electric field in the absorption layer is increased, and thus the bandwidth is improved. Moreover, both the graded doping and graded bandgap structure are optimized. It is found that for the considered UTC-PD, combining use of the optimized graded doping and graded bandgap structure in the absorption layer leads to an improvement of 39.4% in bandwidth. On the other hand, linear doping profile and Gaussian doping profile are proposed to be used in the collection layer. It is shown that the distribution of electric field in the depletion region is improved, which leads to better saturation performance. For the considered UTC-PD, by using the optimized linear doping profile and the Gaussian doping profile, the improvement in saturation current is 18.7% and 25.8%, respectively.

  19. Radiation detection measurements with a new ``Buried Junction'' silicon avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Lecomte, R.; Pepin, C.; Rouleau, D.; Dautet, H.; McIntyre, R. J.; McSween, D.; Webb, P.

    1999-02-01

    An improved version of a recently developed "Buried Junction" avalanche photodiode (APD), designed for use with scintillators, is described and characterized. This device, also called the "Reverse APD", is designed to have a wide depletion layer and thus low capacitance, but to have high gain only for e-h pairs generated within the first few microns of the depletion layer. Thus it has high gain for light from scintillators emitting in the 400-600 nm range, with relatively low dark current noise and it is relatively insensitive to minimum ionizing particles (MIPs). An additional feature is that the metallurgical junction is at the back of the wafer, leaving the front surface free to be coupled to a scintillator without fear of junction contamination. The modifications made in this device, as compared with the earlier diode, have resulted in a lower excess noise factor, lower dark current, and much-reduced trapping. The electrical and optical characteristics of this device are described and measurements of energy and timing resolution of this device with several scintillators (BGO, LSO and GSO) of potential interest in high-energy physics and PET imaging systems are presented.

  20. Initial characterization of a BGO-photodiode detector for high resolution positron emission tomography

    SciTech Connect

    Derenzo, S.E.

    1983-11-01

    Spatial resolution in positron emission tomography is currently limited by the resolution of the detectors. This work presents the initial characterization of a detector design using small bismuth germanate (BGO) crystals individually coupled to silicon photodiodes (SPDs) for crystal identification, and coupled in groups to phototubes (PMTs) for coincidence timing. A 3 mm x 3 mm x 3 mm BGO crystal coupled only to an SPD can achieve a 511 keV photopeak resolution of 8.7% FWHM at -150/sup 0/C, using a pulse peaking time of 10 ..mu..s. When two 3 mm x 3 mm x 15 mm BGO crystals are coupled individually to SPDs and also coupled to a common 14 mm diam PMT, the SPDs detect the 511 keV photopeak with a resolution of 30% FWHM at -76/sup 0/C. In coincidence with an opposing 3 mm wide BGO crystal, the SPDs are able to identify the crystal of interaction with good signal-to-noise ratio, and the detector pair resolution is 2 mm FWHM. 32 references, 7 figures, 3 tables.

  1. Plasmonic field confinement for separate absorption-multiplication in InGaAs nanopillar avalanche photodiodes

    PubMed Central

    Farrell, Alan C.; Senanayake, Pradeep; Hung, Chung-Hong; El-Howayek, Georges; Rajagopal, Abhejit; Currie, Marc; Hayat, Majeed M.; Huffaker, Diana L.

    2015-01-01

    Avalanche photodiodes (APDs) are essential components in quantum key distribution systems and active imaging systems requiring both ultrafast response time to measure photon time of flight and high gain to detect low photon flux. The internal gain of an APD can improve system signal-to-noise ratio (SNR). Excess noise is typically kept low through the selection of material with intrinsically low excess noise, using separate-absorption-multiplication (SAM) heterostructures, or taking advantage of the dead-space effect using thin multiplication regions. In this work we demonstrate the first measurement of excess noise and gain-bandwidth product in III–V nanopillars exhibiting substantially lower excess noise factors compared to bulk and gain-bandwidth products greater than 200 GHz. The nanopillar optical antenna avalanche detector (NOAAD) architecture is utilized for spatially separating the absorption region from the avalanche region via the NOA resulting in single carrier injection without the use of a traditional SAM heterostructure. PMID:26627932

  2. Hybrid integrated metro ring node subsystem on a chip

    NASA Astrophysics Data System (ADS)

    Gerhardt, Reinald; Fujita, Junichiro; Radojevic, Antonije M.; Zhuromskyy, Oleksandr; Eldada, Louay A.

    2003-07-01

    We report on a hybrid integrated metro ring node subsystem on a chip that consists of an array of four independent reconfigurable optical add-drop circuits, each with power monitoring and automatic load balancing, and supporting shared and dedicated protection protocols in two-fiber metro ring optical networks. The four-channel metro ring node chip has polymeric optical waveguiding circuitry, thermally actuated with heaters consisting of resistive strips of metal. Photodiode arrays are flip-chip mounted on top of 45° mirrors cut in the waveguides of optical power taps. The mirrors are fabricated by Excimer laser ablation of the polymer followed by smoothing and metalization. The non-integrated implementation of a metro ring node uses 48 discrete elements, namely 8 1×2 switches, 8 2×2 switches, 8 VOAs, 12 taps, and 12 photodiodes. The proposed integrated solution is an exemplary embodiment of the benefits of optoelectronic integration as it provides, when compared to the discrete solution, significant cost reduction, space savings, lower electrical power consumption, higher reliability (fewer devices, runs cooler), and fewer board-level fiber interconnects.

  3. Fingerprint analysis of Hibiscus mutabilis L. leaves based on ultra performance liquid chromatography with photodiode array detector combined with similarity analysis and hierarchical clustering analysis methods

    PubMed Central

    Liang, Xianrui; Ma, Meiling; Su, Weike

    2013-01-01

    Background: A method for chemical fingerprint analysis of Hibiscus mutabilis L. leaves was developed based on ultra performance liquid chromatography with photodiode array detector (UPLC-PAD) combined with similarity analysis (SA) and hierarchical clustering analysis (HCA). Materials and Methods: 10 batches of Hibiscus mutabilis L. leaves samples were collected from different regions of China. UPLC-PAD was employed to collect chemical fingerprints of Hibiscus mutabilis L. leaves. Results: The relative standard deviations (RSDs) of the relative retention times (RRT) and relative peak areas (RPA) of 10 characteristic peaks (one of them was identified as rutin) in precision, repeatability and stability test were less than 3%, and the method of fingerprint analysis was validated to be suitable for the Hibiscus mutabilis L. leaves. Conclusions: The chromatographic fingerprints showed abundant diversity of chemical constituents qualitatively in the 10 batches of Hibiscus mutabilis L. leaves samples from different locations by similarity analysis on basis of calculating the correlation coefficients between each two fingerprints. Moreover, the HCA method clustered the samples into four classes, and the HCA dendrogram showed the close or distant relations among the 10 samples, which was consistent to the SA result to some extent. PMID:23930008

  4. Fast scintillation timing detector using proportional-mode avalanche photodiode for nuclear resonant scattering experiments in high-energy synchrotron X-ray region

    NASA Astrophysics Data System (ADS)

    Inoue, Keisuke; Kishimoto, Shunji

    2016-01-01

    To obtain both a high count rate of >107 s-1 and a detection efficiency sufficient for high-energy X-rays of >30 keV, we propose a scintillation timing detector using a proportional-mode silicon avalanche photodiode (Si-APD) for synchrotron radiation nuclear resonant scattering. We here present results obtained with a prototype detector using a lead-loaded plastic scintillator (EJ-256) mounted on a proportional-mode Si-APD (active area size: 3 mm in diameter). The detector was operated at ‒35 °C for a better signal-to-noise ratio. Using synchrotron X-rays of 67.41 keV, which is the same energy as the first excited level of 61Ni, we successfully measured pulse-height and time spectra of the scintillation light. A good time resolution of 0.50±0.06 ns (full width at half-maximum) was obtained for 67.41 keV X-rays with a scintillator 3 mm in diameter and 2 mm thick.

  5. Performance assessment of simulated 3D laser images using Geiger-mode avalanche photo-diode: tests on simple synthetic scenarios

    NASA Astrophysics Data System (ADS)

    Coyac, Antoine; Hespel, Laurent; Riviere, Nicolas; Briottet, Xavier

    2015-10-01

    In the past few decades, laser imaging has demonstrated its potential in delivering accurate range images of objects or scenes, even at long range or under bad weather conditions (rain, fog, day and night vision). We note great improvements in the conception and development of single and multi infrared sensors, concerning embedability, circuitry reading capacity, or pixel resolution and sensitivity, allowing a wide diversity of applications (i.e. enhanced vision, long distance target detection and reconnaissance, 3D DSM generation). Unfortunately, it is often difficult to dispose of all the instruments to compare their performance for a given application. Laser imaging simulation has shown to be an interesting alternative to acquire real data, offering a higher flexibility to perform this sensors comparison, plus being time and cost efficient. In this paper, we present a 3D laser imaging end-to-end simulator using a focal plane array with Geiger mode detection, named LANGDOC. This work aims to highlight the interest and capability of this new generation of photo-diodes arrays, especially for airborne mapping and surveillance of high risk areas.

  6. Characterization of a CsI(Tl) array coupled to avalanche photodiodes for the Barrel of the CALIFA calorimeter at the NEPTUN tagged gamma beam facility

    NASA Astrophysics Data System (ADS)

    Gascón, M.; Schnorrenberger, L.; Pietras, B.; Álvarez-Pol, H.; Cortina-Gil, D.; Díaz Fernández, P.; Duran, I.; Glorius, J.; González, D.; Perez-Loureiro, D.; Pietralla, N.; Savran, D.; Sonnabend, K.

    2013-10-01

    Among the variety of crystal calorimeters recently designed for several physics facilities, CALIFA (CALorimeter for In-Flight emitted gAmmas and light-charged particles) has especially demanding requirements since it must perform within a very complicated energy domain (gamma-ray energies from 0.1 to 20 MeV and up to 300 MeV protons). As part of the R&D program for the Barrel section of CALIFA, a reduced geometry prototype was constructed. This prototype consisted of a 3 × 5 array of CsI(Tl) crystals of varying dimensions, coupled to large area avalanche photodiodes. Here reported are the details regarding the construction of the prototype and the experimental results obtained at the NEPTUN tagged gamma beam facility, reconstructing gamma energies up to 10 MeV. Dedicated Monte Carlo simulations of the setup were also performed, enabling a deeper understanding of the experimental data. The experimental results demonstrate the effectiveness of the reconstruction method and helped to establish the most suitable crystal geometry to be employed within the forthcoming calorimeter.

  7. Time-resolved non-contact fluorescence diffuse optical tomography measurements with ultra-fast time-correlated single photon counting avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Bérubé-Lauzière, Yves; Robichaud, Vincent; Lapointe, Éric

    2007-07-01

    The design and fabrication of time-correlated single photon counting (TCSPC) avalanche photodiodes (APDs) and associated quenching circuits have made significant progresses in recent years. APDs with temporal resolutions comparable to microchannel plate photomultiplier tubes (MCP-PMTs) are now available. MCP-PMTs were until these progresses the best TCSPC detectors with timing resolutions down to 30ps. APDs can now achieve these resolutions at a fraction of the cost. Work is under way to make the manufacturing of TCSPC APDs compatible with standard electronics fabrication practices. This should allow to further reduce their cost and render them easier to integrate in complex multi-channel TCSPC electronics, as needed in diffuse optical tomography (DOT) systems. Even if their sensitive area is much smaller than that of the ubiquitous PMT used in TCSPC, we show that with appropriate selection of optical components, TCSPC APDs can be used in time-domain DOT. To support this, we present experimental data and calculations clearly demonstrating that comparable measurements can be obtained with APDs and PMTs. We are, to our knowledge, the first group using APDs in TD DOT, in particular in non-contact TD fluorescence DOT.

  8. Antioxidant activity evaluation and HPLC-photodiode array/MS polyphenols analysis of pomegranate juice from selected italian cultivars: A comparative study.

    PubMed

    Fanali, Chiara; Belluomo, Maria Giovanna; Cirilli, Marco; Cristofori, Valerio; Zecchini, Maurizio; Cacciola, Francesco; Russo, Marina; Muleo, Rosario; Dugo, Laura

    2016-07-01

    Chemical composition of pomegranate juice can vary due to cultivar, area of cultivation, ripening, climate, and other variables. This study investigates the polyphenolic composition and antioxidant activity of juices obtained from six old Italian pomegranate cultivars. Fruit accessions physicochemical characteristics were determined. Total polyphenols content (TPC), anthocyanin content (TAC) and proanthocyanidin content (TPAC) were measured in the juice samples. Phenolic bioactive molecules were analyzed by HPLC-photodiode array (PDA)/ESI-MS in all the pomegranate juices. In total, seven nonanthocyanidinic and six anthocyanidinic compounds were identified. The six anthocyanins were found in all juices although at different amounts. These results were correlated with antioxidant activity measured by three different chemical assays: 2,2 diphenyl-1-picrylhydrazyl (DPPH(•) ) scavenging activity assay, Trolox equivalent antioxidant capacity (TEAC) method and ferric reducing-antioxidant power (FRAP) assay. Pomegranate juices obtained by six different varieties show variable polyphenolic content and antioxidant activity. The antioxidant capacity methods used have shown variable sensitivity, supporting the hypothesis that different methods for the assessment of antioxidant capacity of food compounds are indeed necessary, due to complexity of sample composition and assay chemical mechanism and sensitivity. Juices from Italian pomegranate show good levels of polyphenols content and antioxidant activity making them potential candidates for employment in the food industry. PMID:26814700

  9. Characterization of Large Area APDs for the EXO-200 Detector

    SciTech Connect

    Neilson, R.; LePort, F.; Pocar, A.; Kumar, K.; Odian, A.; Prescott, C.Y.; Tenev, V.; Ackerman, N.; Akimov, D.; Auger, M.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Conley, R.; Cook, S.; deVoe, R.; Dolinski, M.J.; Fairbank, W., Jr.; Farine, J.; Fierlinger, P.; Flatt, B.; /Stanford U., Phys. Dept. /Bern U., LHEP /Stanford U., Phys. Dept. /Maryland U. /Colorado State U. /Laurentian U. /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Alabama U. /SLAC /Colorado State U. /Stanford U., Phys. Dept. /Alabama U. /Stanford U., Phys. Dept. /Alabama U. /SLAC /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Carleton U. /Stanford U., Phys. Dept. /Bern U., LHEP /SLAC /Laurentian U. /SLAC /Maryland U.

    2011-12-02

    EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169 K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector.

  10. Hybrid Gear

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F. (Inventor); Roberts, Gary D. (Inventor)

    2016-01-01

    A hybrid gear consisting of metallic outer rim with gear teeth and metallic hub in combination with a composite lay up between the shaft interface (hub) and gear tooth rim is described. The composite lay-up lightens the gear member while having similar torque carrying capability and it attenuates the impact loading driven noise/vibration that is typical in gear systems. The gear has the same operational capability with respect to shaft speed, torque, and temperature as an all-metallic gear as used in aerospace gear design.

  11. Temperature dependent characterization of gallium arsenide X-ray mesa p-i-n photodiodes

    NASA Astrophysics Data System (ADS)

    Lioliou, G.; Meng, X.; Ng, J. S.; Barnett, A. M.

    2016-03-01

    Electrical characterization of two GaAs p+-i-n+ mesa X-ray photodiodes over the temperature range 0 °C to 120 °C together with characterization of one of the diodes as an X-ray detector over the temperature range 0 °C to 60 °C is reported as part of the development of photon counting X-ray spectroscopic systems for harsh environments. The randomly selected diodes were fully etched and unpassivated. The diodes were 200 μm in diameter and had 7 μm thick i layers. The leakage current density was found to increase from (3 ± 1) nA/cm-2 at 0 °C to (24.36 ± 0.05) μA/cm-2 at 120 °C for D1 and from a current density smaller than the uncertainty (0.2 ± 1.2) nA/cm-2 at 0 °C to (9.39 ± 0.02) μA/cm-2 at 120 °C for D2 at the maximum investigated reverse bias (15 V). The best energy resolution (FWHM at 5.9 keV) was achieved at 5 V reverse bias, at each temperature; 730 eV at 0 °C, 750 eV at 20 °C, 770 eV at 40 °C, and 840 eV at 60 °C. It was found that the parallel white noise was the main source of the photopeak broadening only when the detector operated at 60 °C, at 5 V, 10 V, and 15 V reverse bias and at long shaping times (>5 μs), whereas the sum of the dielectric noise and charge trapping noise was the dominant source of noise for all the other spectra.

  12. Characterization of gallium arsenide X-ray mesa p-i-n photodiodes at room temperature

    NASA Astrophysics Data System (ADS)

    Lioliou, G.; Meng, X.; Ng, J. S.; Barnett, A. M.

    2016-03-01

    Two GaAs mesa p+-i-n+ photodiodes intended for photon counting X-ray spectroscopy, having an i layer thickness of 7 μm and diameter of 200 μm, have been characterized electrically, for their responsivity at the wavelength range 580 nm to 980 nm and one of them for its performance at detection of soft X-rays, at room temperature. Dark current and capacitance measurements as a function of applied forward and reverse bias are presented. The results show low leakage current densities, in the range of nA/cm2 at the maximum internal electric field (22 kV/cm). The unintentional doping concentration of the i layer, calculated from capacitance measurements, was found to be <1014 cm-3. Photocurrent measurements were performed under visible and near infrared light illumination for both diodes. The analysis of these measurements suggests the presence of a non-active (dead) layer (0.16 μm thickness) at the p+ side top contact interface, where the photogenerated carriers do not contribute to the photocurrent, possibly due to recombination. One of the diodes, D1, was also characterized as detector for room temperature photon counting X-ray spectroscopy; the best energy resolution achieved (FWHM) at 5.9 keV was 745 eV. The noise analysis of the system, based on spectra obtained at different shaping times and applied reverse biases, showed that the dominant source of noise is the dielectric noise. It was also calculated that there was at least (165±24) eV charge trapping noise at 0 V.

  13. Printed hybrid systems

    NASA Astrophysics Data System (ADS)

    Karioja, Pentti; Mäkinen, Jukka-Tapani; Keränen, Kimmo; Aikio, Janne; Alajoki, Teemu; Jaakola, Tuomo; Koponen, Matti; Keränen, Antti; Heikkinen, Mikko; Tuomikoski, Markus; Suhonen, Riikka; Hakalahti, Leena; Kopola, Pälvi; Hast, Jukka; Liedert, Ralf; Hiltunen, Jussi; Masuda, Noriyuki; Kemppainen, Antti; Rönkä, Kari; Korhonen, Raimo

    2012-04-01

    This paper presents research activities carried out at VTT Technical Research Centre of Finland in the field of hybrid integration of optics, electronics and mechanics. Main focus area in our research is the manufacturing of electronic modules and product structures with printed electronics, film-over-molding and polymer sheet lamination technologies and the goal is in the next generation of smart systems utilizing monolithic polymer packages. The combination of manufacturing technologies such as roll-to-roll -printing, injection molding and traditional component assembly is called Printed Hybrid Systems (PHS). Several demonstrator structures have been made, which show the potential of polymer packaging technology. One demonstrator example is a laminated structure with embedded LED chips. Element thickness is only 0.3mm and the flexible stack of foils can be bent in two directions after assembly process and was shaped curved using heat and pressure. The combination of printed flexible circuit boards and injection molding has also been demonstrated with several functional modules. The demonstrators illustrate the potential of origami electronics, which can be cut and folded to 3D shapes. It shows that several manufacturing process steps can be eliminated by Printed Hybrid Systems technology. The main benefits of this combination are small size, ruggedness and conformality. The devices are ideally suited for medical applications as the sensitive electronic components are well protected inside the plastic and the structures can be cleaned easily due to the fact that they have no joints or seams that can accumulate dirt or bacteria.

  14. Hybrid Propulsion Technology Program

    NASA Technical Reports Server (NTRS)

    Jensen, G. E.; Holzman, A. L.

    1990-01-01

    Future launch systems of the United States will require improvements in booster safety, reliability, and cost. In order to increase payload capabilities, performance improvements are also desirable. The hybrid rocket motor (HRM) offers the potential for improvements in all of these areas. The designs are presented for two sizes of hybrid boosters, a large 4.57 m (180 in.) diameter booster duplicating the Advanced Solid Rocket Motor (ASRM) vacuum thrust-time profile and smaller 2.44 m (96 in.), one-quater thrust level booster. The large booster would be used in tandem, while eight small boosters would be used to achieve the same total thrust. These preliminary designs were generated as part of the NASA Hybrid Propulsion Technology Program. This program is the first phase of an eventual three-phaes program culminating in the demonstration of a large subscale engine. The initial trade and sizing studies resulted in preferred motor diameters, operating pressures, nozzle geometry, and fuel grain systems for both the large and small boosters. The data were then used for specific performance predictions in terms of payload and the definition and selection of the requirements for the major components: the oxidizer feed system, nozzle, and thrust vector system. All of the parametric studies were performed using realistic fuel regression models based upon specific experimental data.

  15. ) Hybrid Composite

    NASA Astrophysics Data System (ADS)

    Show, Bijay Kumar; Mondal, Dipak Kumar; Maity, Joydeep

    2014-12-01

    In this research work, the dry sliding wear behavior of 6351 Al-(4 vol.% SiC + 4 vol.% Al2O3) hybrid composite was investigated at low sliding speed (1 m/s) against a hardened EN 31 disk at different loads. In general, the wear mechanism involved adhesion (along with associated subsurface cracking and delamination) and microcutting abrasion at lower load. While at higher load, abrasive wear involving microcutting and microploughing along with adherent oxide formation was observed. The overall wear rate increased with increasing normal load. The massive particle clusters as well as individual reinforcement particles were found to stand tall to resist abrasive wear. Besides, at higher load, the generation of adherent nodular tribo-oxide through nucleation and epitaxial growth on existing Al2O3 particles lowered down the wear rate. Accordingly, at any normal load, 6351 Al-(4 vol.% SiC + 4 vol.% Al2O3) hybrid composite exhibited superior wear resistance (lower overall wear rate) than the reported wear resistance of monolithic 6351 Al alloy.

  16. Hybrid Simulator

    Energy Science and Technology Software Center (ESTSC)

    2005-10-15

    HybSim (short for Hybrid Simulator) is a flexible, easy to use screening tool that allows the user to quanti the technical and economic benefits of installing a village hybrid generating system and simulates systems with any combination of —Diesel generator sets —Photovoltaic arrays -Wind Turbines and -Battery energy storage systems Most village systems (or small population sites such as villages, remote military bases, small communities, independent or isolated buildings or centers) depend on diesel generationmore » systems for their source of energy. HybSim allows the user to determine other "sources" of energy that can greatly reduce the dollar to kilo-watt hour ratio. Supported by the DOE, Energy Storage Program, HybSim was initially developed to help analyze the benefits of energy storage systems in Alaskan villages. Soon after its development, other sources of energy were added providing the user with a greater range of analysis opportunities and providing the village with potentially added savings. In addition to village systems, HybSim has generated interest for use from military institutions in energy provisions and USAID for international village analysis.« less

  17. Hybridization in a warmer world

    PubMed Central

    Chunco, Amanda J

    2014-01-01

    Climate change is profoundly affecting the evolutionary trajectory of individual species and ecological communities, in part through the creation of novel species assemblages. How climate change will influence competitive interactions has been an active area of research. Far less attention, however, has been given to altered reproductive interactions. Yet, reproductive interactions between formerly isolated species are inevitable as populations shift geographically and temporally as a result of climate change, potentially resulting in introgression, speciation, or even extinction. The susceptibility of hybridization rates to anthropogenic disturbance was first recognized in the 1930s. To date, work on anthropogenically mediated hybridization has focused primarily on either physical habitat disturbance or species invasion. Here, I review recent literature on hybridization to identify how ecological responses to climate change will increase the likelihood of hybridization via the dissolution of species barriers maintained by habitat, time, or behavior. Using this literature, I identify several cases where novel hybrid zones have recently formed, likely as a result of changing climate. Future research should focus on identifying areas and taxonomic groups where reproductive species interactions are most likely to be influenced by climate change. Furthermore, a better understanding of the evolutionary consequences of climate-mediated secondary contact is urgently needed. Paradoxically, hybridization is both a major conservation concern and an important source of novel genetic and phenotypic variation. Hybridization may therefore both contribute to increasing rates of extinction and stimulate the creation of novel phenotypes that will speed adaptation to novel climates. Predicting which result will occur following secondary contact will be an important contribution to conservation for many species. PMID:24963394

  18. Suppression of dark current in germanium-tin on silicon p-i-n photodiode by a silicon surface passivation technique.

    PubMed

    Dong, Yuan; Wang, Wei; Lei, Dian; Gong, Xiao; Zhou, Qian; Lee, Shuh Ying; Loke, Wan Khai; Yoon, Soon-Fatt; Tok, Eng Soon; Liang, Gengchiau; Yeo, Yee-Chia

    2015-07-13

    We demonstrate that a complementary metal-oxide-semiconductor (CMOS) compatible silicon (Si) surface passivation technique effectively suppress the dark current originating from the mesa sidewall of the Ge(0.95)Sn(0.05) on Si (Ge(0.95)Sn(0.05)/Si) p-i-n photodiode. Current-voltage (I-V) characteristics show that the sidewall surface passivation technique could reduce the surface leakage current density (Jsurf) of the photodiode by ~100 times. A low dark current density (Jdark) of 0.073 A/cm(2) at a bias voltage of -1 V is achieved, which is among the lowest reported values for Ge(1-x)Sn(x)/Si p-i-n photodiodes. Temperature-dependent I-V measurement is performed for the Si-passivated and non-passivated photodiodes, from which the activation energies of dark current are extracted to be 0.304 eV and 0.142 eV, respectively. In addition, the optical responsivity of the Ge(0.95)Sn(0.05)/Si p-i-n photodiodes to light signals with wavelengths ranging from 1510 nm to 1877 nm is reported. PMID:26191919

  19. Hybridized tetraquarks

    NASA Astrophysics Data System (ADS)

    Esposito, A.; Pilloni, A.; Polosa, A. D.

    2016-07-01

    We propose a new interpretation of the neutral and charged X , Z exotic hadron resonances. Hybridized-tetraquarks are neither purely compact tetraquark states nor bound or loosely bound molecules but rather a manifestation of the interplay between the two. While meson molecules need a negative or zero binding energy, its counterpart for h-tetraquarks is required to be positive. The formation mechanism of this new class of hadrons is inspired by that of Feshbach metastable states in atomic physics. The recent claim of an exotic resonance in the Bs0 π± channel by the D0 Collaboration and the negative result presented subsequently by the LHCb Collaboration are understood in this scheme, together with a considerable portion of available data on X , Z particles. Considerations on a state with the same quantum numbers as the X (5568) are also made.

  20. Linear arrays of InGaAs/InP avalanche photodiodes for 1.0-1.7 micron

    NASA Technical Reports Server (NTRS)

    Ackley, D. E.; Hladky, J.; Lange, M. J.; Mason, S.; Erickson, G.; Olsen, G. H.; Ban, V. S.; Forrest, S. R.; Staller, C.

    1990-01-01

    Separate absorption and multiplication InGaAs/InP avalanche photodiodes (SAM-APDs) with a floating guard ring structure that is well-suited to array applications have been successfully demonstrated. Individual APDs have breakdown voltages greater than 80 V, multiplications over 40 at 100 nA dark current, and uniform spatial gain profiles. Uniform I-V characteristics and gains have been measured over linear dimensions as large as 1.2 cm. Gains over 10 at low multiplied dark currents were measured on 21 consecutive devices at the wafer level.

  1. A new method to improve multiplication factor in micro-pixel avalanche photodiodes with high pixel density

    NASA Astrophysics Data System (ADS)

    Sadygov, Z.; Ahmadov, F.; Khorev, S.; Sadigov, A.; Suleymanov, S.; Madatov, R.; Mehdiyeva, R.; Zerrouk, F.

    2016-07-01

    Presented is a new model describing development of the avalanche process in time, taking into account the dynamics of electric field within the depleted region of the diode and the effect of parasitic capacitance shunting individual quenching micro-resistors on device parameters. Simulations show that the effective capacitance of a single pixel, which defines the multiplication factor, is the sum of the pixel capacitance and a parasitic capacitance shunting its quenching micro-resistor. Conclusions obtained as a result of modeling open possibilities of improving the pixel gain in micropixel avalanche photodiodes with high pixel density (or low pixel capacitance).

  2. Effects of Displacement Damage on the Time-Resolved Gain and Bandwidth of a Low Breakdown Voltage Si Avalanche Photodiode

    NASA Technical Reports Server (NTRS)

    Laird, Jamie S.; Onoda, Shinobu; Hirao, Toshio; Becker, Heidi; Johnston, Allan; Laird, Jamie S.; Itoh, Hisayoshi

    2006-01-01

    Effects of displacement damage and ionization damage induced by gamma irradiation on the dark current and impulse response of a high-bandwidth low breakdown voltage Si Avalanche Photodiode has been investigated using picosecond laser microscopy. At doses as high as 10Mrad (Si) minimal alteration in the impulse response and bandwidth were observed. However, dark current measurements also performed with and without biased irradiation exhibit anomalously large damage factors for applied biases close to breakdown. The absence of any degradation in the impulse response is discussed as are possible mechanisms for higher dark current damage factors observed for biased irradiation.

  3. Spatially resolved diffuse reflectance spectroscopy of two-layer turbid media by densely packed multi-pixel photodiode reflectance probe

    NASA Astrophysics Data System (ADS)

    Senlik, Ozlem; Greening, Gage; Muldoon, Timothy J.; Jokerst, Nan M.

    2016-03-01

    Spatially-resolved diffuse reflectance (SRDR) measurements provide photon path information, and enable layered tissue analysis. This paper presents experimental SRDR measurements on two-layer PDMS skin tissue-mimicking phantoms of varying top layer thicknesses, and bulk phantoms of varying optical properties using concentric multi-pixel photodiode array (CMPA) probes, and corresponding forward Monte Carlo simulations. The CMPA is the most densely packed semiconductor SRDR probe reported to date. Signal contrasts between the single layer phantom and bi-layer phantoms with varying top layer thicknesses are as high as 80%. The mean error between the Monte Carlo simulations and the experiment is less than 6.2 %.

  4. Characterization of the Hamamatsu S8664 avalanche photodiode for X-ray and VUV-light detection

    NASA Astrophysics Data System (ADS)

    Lux, T.; Freitas, E. D. C.; Amaro, F. D.; Ballester, O.; Jover-Manas, G. V.; Martín, C.; Monteiro, C. M. B.; Sánchez, F.; Rico, J.

    2012-09-01

    We present the first operation of the VUV-sensitive avalanche photodiode (APD) from Hamamatsu to xenon scintillation light and to direct X-rays of 22.1 keV and 5.9 keV. A large non-linear response was observed for the direct X-ray detection. At 415 V APD bias voltage it was of about 30% for 22.1 keV and about 45% for 5.9 keV. The quantum efficiency for 172 nm photons has been measured to be 69±15%.

  5. Development of a (Hg, Cd)Te photodiode detector, Phase 2. [for 10.6 micron spectral region

    NASA Technical Reports Server (NTRS)

    1972-01-01

    High speed sensitive (Hg,Cd)Te photodiode detectors operating in the 77 to 90 K temperature range have been developed for the 10.6 micron spectral region. P-N junctions formed by impurity (gold) diffusion in p-type (Hg, Cd) Te have been investigated. It is shown that the bandwidth and quantum efficiency of a diode are a constant for a fixed ratio of mobility/lifetime ratio of minority carriers. The minority carrier mobility and lifetime uniquely determine the bandwidth and quantum efficiency and indicate the shallow n on p (Hg,Cd) Te diodes are preferable as high performance, high frequency devices.

  6. GaAs-based triangular barrier photodiodes with embedded type-II GaSb quantum dots

    NASA Astrophysics Data System (ADS)

    Vitushinskiy, Pavel; Ohmori, Masato; Kuroda, Tomohiro; Noda, Takeshi; Kawazu, Takuya; Sakaki, Hiroyuki

    2016-05-01

    We fabricate GaAs-based triangular barrier photodiodes (TBPs), in which type-II GaSb quantum dots (QDs) are embedded in the vertex part of their triangular barriers. Their current–voltage characteristics and photo-responses are studied at low temperatures to show that GaSb QDs enhance the number and lifetime of photo-generated holes that are trapped by QDs in the barrier, resulting in the increase in the electron current around positively charged QDs. An extremely high responsivity of 109 A/W is achieved.

  7. Design of Low Power CMOS Read-Out with TDI Function for Infrared Linear Photodiode Array Detectors

    NASA Technical Reports Server (NTRS)

    Vizcaino, Paul; Ramirez-Angulo, Jaime; Patel, Umesh D.

    2007-01-01

    A new low voltage CMOS infrared readout circuit using the buffer-direct injection method is presented. It uses a single supply voltage of 1.8 volts and a bias current of 1uA. The time-delay integration technique is used to increase the signal to noise ratio. A current memory circuit with faulty diode detection is used to remove dark current for background compensation and to disable a photodiode in a cell if detected as faulty. Simulations are shown that verify the circuit that is currently in fabrication in 0.5ym CMOS technology.

  8. InGaAs triangular barrier photodiodes for high-responsivity detection of near-infrared light

    NASA Astrophysics Data System (ADS)

    Sugimura, Kazuya; Ohmori, Masato; Noda, Takeshi; Kojima, Tomoya; Kado, Sakunari; Vitushinskiy, Pavel; Iwata, Naotaka; Sakaki, Hiroyuki

    2016-06-01

    InGaAs triangular barrier (TB) structures of various barrier thicknesses have been formed on InP substrates. With them, we have fabricated TB photodiodes that yield a very high responsivity of 2.3 × 104 A/W at 100 K for the 1312 nm light of 320 fW power. By passivating the diode surface with polyimide, the dark current has been markedly reduced. Diodes with thicker barriers show higher sensitivity and responsivity, reflecting the enhancement of the barrier lowering effect by photogenerated holes.

  9. Evaluation of a fast single-photon avalanche photodiode for measurement of early transmitted photons through diffusive media.

    PubMed

    Mu, Ying; Valim, Niksa; Niedre, Mark

    2013-06-15

    We tested the performance of a fast single-photon avalanche photodiode (SPAD) in measurement of early transmitted photons through diffusive media. In combination with a femtosecond titanium:sapphire laser, the overall instrument temporal response time was 59 ps. Using two experimental models, we showed that the SPAD allowed measurement of photon-density sensitivity functions that were approximately 65% narrower than the ungated continuous wave case at very early times. This exceeds the performance that we have previously achieved with photomultiplier-tube-based systems and approaches the theoretical maximum predicted by time-resolved Monte Carlo simulations. PMID:23938989

  10. A design for a linear array PIN photodiode for use in a Computed mammo-Tomography (CmT) system

    NASA Astrophysics Data System (ADS)

    Park, Shin-Woong; Yuk, Sunwoo; Park, Jung-Byung; Yi, Yun

    2009-10-01

    A p-i-n (PIN) photodiode has been used in a solid-state detector for X-ray detection as a photosensor of visible light from the scintillator. The most sensitive material used as low-energy X-ray detector in the mammography system is a Gd 2O 2S (GOS). As the light from GOS having a short wavelength in the range of 450-700 nm (peak at 510 nm) is absorbed within a very shallow layer near the surface of photodiode before arriving at depletion region and does not contribute to the signal. For designing the PIN photodiode, it is important to make p-layer as shallow as possible. In order to achieve shallow junction, the optimum conditions of ion implantation such as thickness of SiO 2 oxide barrier, tilting angle of the wafer with respect to incident ion beam, and annealing conditions, have been determined using simulation results. The penetration depths are about 2 μm for 510 nm, and 7 μm for 700 nm. It is necessary for adequate depletion depth (about 10 μm) to acquire the entire incident light. So far, wafers of ≥1000 and ≥150 Ω cm resistivity were chosen, which offer about 15 and 6 μm depletion depth, respectively. The pixel pitch of photodiode is 0.4 mm×3.0 mm and one module has 64 channels in linear array. Depth of the active p-layer is under 0.3 μm in zero bias. Measured leakage currents under 10 pA/mm 2 for both diodes and junction capacitances are 16 and 29 pF/mm 2 in zero bias for the diodes of ≥150 and ≥1000 Ω cm resistivity, respectively. The breast phantom, which was scanned by the Computed mammo-Tomography (CmT) system with two different detector modules and the data acquisition system, was developed. Little differences for distinct light absorption were shown in the three-dimensional images acquired in this study.

  11. The calorimeter of the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Grove, J. Eric; Johnson, W. Neil

    2010-07-01

    The Large Area Telescope (LAT), the primary instrument on the Fermi Gamma-ray Space Telescope, has been making revolutionary observations of the high-energy (20 MeV - 300 GeV) gamma-ray sky since its launch in June 2008. The LAT calorimeter is a modular array of 1536 CsI(Tl) crystals supported within 16 carbon fiber structures and read out at each crystal end with silicon PIN photodiodes to provide both energy and position information. The hodoscopic crystal stack allows imaging of electromagnetic showers and cosmic rays for improved energy measurement and background rejection. Signals from the array of photodiodes are processed by custom ASICs and commercial ADCs. We describe the calorimeter design and the primary factors that led those design choices.

  12. Arabidopsis hybrid speciation processes

    PubMed Central

    Schmickl, Roswitha; Koch, Marcus A.

    2011-01-01

    The genus Arabidopsis provides a unique opportunity to study fundamental biological questions in plant sciences using the diploid model species Arabidopsis thaliana and Arabidopsis lyrata. However, only a few studies have focused on introgression and hybrid speciation in Arabidopsis, although polyploidy is a common phenomenon within this genus. More recently, there is growing evidence of significant gene flow between the various Arabidopsis species. So far, we know Arabidopsis suecica and Arabidopsis kamchatica as fully stabilized allopolyploid species. Both species evolved during Pleistocene glaciation and deglaciation cycles in Fennoscandinavia and the amphi-Beringian region, respectively. These hybrid studies were conducted either on a phylogeographic scale or reconstructed experimentally in the laboratory. In our study we focus at a regional and population level. Our research area is located in the foothills of the eastern Austrian Alps, where two Arabidopsis species, Arabidopsis arenosa and A. lyrata ssp. petraea, are sympatrically distributed. Our hypothesis of genetic introgression, migration, and adaptation to the changing environment during the Pleistocene has been confirmed: We observed significant, mainly unidirectional gene flow between the two species, which has given rise to the tetraploid A. lyrata. This cytotype was able to escape from the narrow ecological niche occupied by diploid A. lyrata ssp. petraea on limestone outcrops by migrating northward into siliceous areas, leaving behind a trail of genetic differentiation. PMID:21825128

  13. Alternative Spectral Photoresponse in a p-Cu2ZnSnS4/n-GaN Heterojunction Photodiode by Modulating Applied Voltage.

    PubMed

    Yang, Gang; Li, Yong-Feng; Yao, Bin; Ding, Zhan-Hui; Deng, Rui; Fang, Xuan; Wei, Zhi-Peng

    2015-08-01

    We report alternative visible and ultraviolet light response spectra in a p-Cu2ZnSnS4 (p-CZTS)/n-GaN heterojunction photodiode. A CZTS film was deposited on an n-GaN/sapphire substrate using a magnetron sputtering method. Current-voltage characteristic of the p-CZTS/n-GaN heterojunction photodiode showed a good rectifying behavior. The spectral response measurements indicate that the response wavelength of the photodiode can be tuned from ultraviolet to visible regions via applying zero and reverse bias. A band alignment at the interface of the p-CZTS/n-GaN heterojunction was proposed to interpret the spectral response of the device. PMID:26182428

  14. Photodiode-Based X-Ray Beam-Position Monitor With High Spatial-Resolution for the NSLS-II Beamlines

    SciTech Connect

    Yoon, P.S.; Siddons, D. P.

    2009-05-25

    We developed a photodiode-based monochromatic X-ray beam-position monitor (X-BPM) with high spatial resolution for the project beamlines of the NSLS-II. A ring array of 32 Si PIN-junction photodiodes were designed for use as a position sensor, and a low-noise HERMES4 ASIC chip was integrated into the electronic readout system. A series of precision measurements to characterize electrically the Si-photodiode sensor and the ASIC chip demonstrated that the inherent noise is sufficiently below tolerance levels. Following up modeling of detector's performance, including geometrical optimization using a Gaussian beam, we fabricated and assembled a first prototype. In this paper, we describe the development of this new state-of-the-art X-ray BPM along the beamline, in particular, downstream from the monochromator.

  15. Betabox: a beta particle imaging system based on a position sensitive avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Dooraghi, A. A.; Vu, N. T.; Silverman, R. W.; Farrell, R.; Shah, K. S.; Wang, J.; Heath, J. R.; Chatziioannou, A. F.

    2013-06-01

    A beta camera has been developed that allows planar imaging of the spatial and temporal distribution of beta particles using a 14 × 14 mm2 position sensitive avalanche photodiode (PSAPD). This camera system, which we call Betabox, can be directly coupled to microfluidic chips designed for cell incubation or other biological applications. Betabox allows for imaging the cellular uptake of molecular imaging probes labeled with charged particle emitters such as 18F inside these chips. In this work, we investigate the quantitative imaging capabilities of Betabox for 18F beta particles, in terms of background rate, efficiency, spatial resolution, and count rate. Measurements of background and spatial resolution are considered both at room temperature (21 °C ± 1 °C) and at an elevated operating temperature (37 °C ± 1 °C), as is often required for biological assays. The background rate measured with a 4 keV energy cutoff is below 2 cph mm-2 at both 21 and 37 °C. The absolute efficiency of Betabox for the detection of 18F positron sources in contact with a PSAPD with the surface passivated from ambient light and damage is 46% ± 1%. The lower detection limit is estimated using the Rose Criterion to be 0.2 cps mm-2 for 1 min acquisitions and a 62 × 62 µm2 pixel size. The upper detection limit is approximately 21 000 cps. The spatial resolution at both 21 and 37 °C ranges from 0.4 mm FWHM at the center of the field of view (FOV), and degrades to 1 mm at a distance of 5 mm away from center yielding a useful FOV of approximately 10 × 10 mm2. We also investigate the effects on spatial resolution and sensitivity that result from the use of a polymer based microfluidic chip. For these studies we place varying layers of low-density polyethylene (LDPE) between the detector and the source and find that the spatial resolution degrades by ˜180 µm for every 100 µm of LDPE film. Sensitivity is reduced by half with the inclusion of ˜200 µm of additional LDPE film. Lastly

  16. Lutetium oxyorthosilicate block detector readout by avalanche photodiode arrays for high resolution animal PET

    NASA Astrophysics Data System (ADS)

    Pichler, B. J.; Swann, B. K.; Rochelle, J.; Nutt, R. E.; Cherry, S. R.; Siegel, S. B.

    2004-09-01

    Avalanche photodiodes (APDs) have proven to be useful as light detectors for high resolution positron emission tomography (PET). Their compactness makes these devices excellent candidates for replacing bulky photomultiplier tubes (PMTs) in PET systems where space limitations are an issue. The readout of densely packed, 10 × 10 lutetium oxyorthosilicate (LSO) block detectors (crystal size 2.0 × 2.0 × 12 mm3) with custom-built monolithic 3 × 3 APD arrays was investigated. The APDs had a 5 × 5 mm2 active surface and were arranged on a 6.25 mm pitch. The dead space on the edges of the array was 1.25 mm. The APDs were operated at a bias voltage of approximately 380 V for a gain of 100 and a dark current of 10 nA per APD. The standard deviation in gain between the APDs in the array ranged from 1.8 to 6.5% as the gain was varied from 50 to 108. A fast, low-noise, multi-channel charge sensitive preamplifier application-specific integrated circuit (ASIC) was developed for the APD readout. The amplifier had a rise time of 8 ns, a noise floor of 515 e- rms and a 9 e- pF-1 noise slope. An acquired flood image showed that all 100 crystals from the block detector could be resolved. Timing measurements with single-channel LSO-APD detectors, as well as with the array, against a plastic scintillator and PMT assembly showed a time resolution of 1.2 ns and 2.5 ns, respectively. The energy resolution measured with a single 4.0 × 4.0 × 10 mm3 LSO crystal, wrapped in four-layer polytetrafluoroethylene (PTFE) tape and coupled with optical grease on a single APD of the array, yielded 15% (full width at half maximum, FWHM) at 511 keV. Stability tests over 9 months of operation showed that the APD arrays do not degrade appreciably. These results demonstrate the ability to decode densely packed LSO scintillation blocks with compact APD arrays. The good timing and energy resolution makes these detectors suitable for high resolution PET.

  17. Betabox: a beta particle imaging system based on a position sensitive avalanche photodiode

    PubMed Central

    Dooraghi, AA; Vu, NT; Silverman, RW; Farrell, R; Shah, KS; Wang, J; Heath, JR; Chatziioannou, AF

    2013-01-01

    A beta camera has been developed that allows planar imaging of the spatial and temporal distribution of beta particles using a 14 × 14 mm2 position sensitive avalanche photodiode (PSAPD). This camera system, which we call Betabox, can be directly coupled to microfluidic chips designed for cell incubation or other biological applications. Betabox allows for imaging the cellular uptake of molecular imaging probes labeled with charged particle emitters such as 18F inside these chips. In this work, we investigate the quantitative imaging capabilities of Betabox for 18F beta particles, in terms of background rate, efficiency, spatial resolution, and count rate. Measurements of background and spatial resolution are considered both at room temperature (21 °C ± 1 °C) and at an elevated operating temperature (37 °C ± 1 °C), as is often required for biological assays. The background rate measured with a 4 keV energy cutoff is below 2 cph mm−2 at both 21 and 37 °C. The absolute efficiency of Betabox for the detection of 18F positron sources in contact with a PSAPD with the surface passivated from ambient light and damage is 46% ± 1%. The lower detection limit is estimated using the Rose Criterion to be 0.2 cps mm−2 for 1 min acquisitions and a 62 × 62 µm2 pixel size. The upper detection limit is approximately 21 000 cps. The spatial resolution at both 21 and 37 °C ranges from 0.4 mm FWHM at the center of the field of view (FOV), and degrades to 1 mm at a distance of 5 mm away from center yielding a useful FOV of approximately 10 × 10 mm2. We also investigate the effects on spatial resolution and sensitivity that result from the use of a polymer based microfluidic chip. For these studies we place varying layers of low-density polyethylene (LDPE) between the detector and the source and find that the spatial resolution degrades by ~180 µm for every 100 µm of LDPE film. Sensitivity is reduced by half with the inclusion of ~200 µm of additional LDPE film

  18. Visible-blind ultraviolet photodiode fabricated by UV oxidation of metallic zinc on p-Si

    NASA Astrophysics Data System (ADS)

    Zhang, Dongyuan; Uchida, Kazuo; Nozaki, Shinji

    2015-09-01

    A UV photodiode fabricated by the UV oxidation of a metallic zinc thin film on p-Si has manifested unique photoresponse characteristics. The electron concentration found by the Hall measurement was 3 × 1016 cm-3, and such a low electron concentration resulted in a low visible photoluminescence. UV illumination enhances the oxidation at low temperatures and decreases the concentration of the oxygen vacancies. The I-V characteristic showed a good rectification with a four-order magnitude difference in the forward and reverse currents at 2 V, and its linear and frequency independent C-2-V characteristic confirmed an abrupt pn junction. The photoresponse showed a visible blindness with a responsivity ratio of UV and visible light as high as 100. Such a visible-blind photoresponse was attributed to the optimum thickness of the SiO2 formed on the Si surface during the UV oxidation at 400 °C. A lower potential barrier to holes at the ZnO/SiO2 interface facilitates Fowler-Nordheim tunneling of the photo-generated holes during the UV illumination, while a higher potential barrier to electrons efficiently blocks transport of the photo-generated electrons to the ZnO during the visible light illumination. The presence of oxide resulted in a slow photoresponse to the turn-on and off of the UV light. A detailed analysis is presented to understand how the photo-generated carriers contribute step by step to the photocurrent. In addition to the slow photoresponse associated with the SiO2 interfacial layer, the decay of the photocurrent was found extremely slow after turn-off of the UV light. Such a slow decay of the photocurrent is referred to as a persistent photoconductivity, which is caused by metastable deep levels. It is hypothesized that Zn vacancies form such a deep level, and that the photo-generated electrons need to overcome a thermal-energy barrier for capture. The ZnO film by the UV oxidation at 400 °C was found to be rich in oxygen and deficient in zinc.

  19. Visible-blind ultraviolet photodiode fabricated by UV oxidation of metallic zinc on p-Si

    SciTech Connect

    Zhang, Dongyuan; Uchida, Kazuo; Nozaki, Shinji

    2015-09-07

    A UV photodiode fabricated by the UV oxidation of a metallic zinc thin film on p-Si has manifested unique photoresponse characteristics. The electron concentration found by the Hall measurement was 3 × 10{sup 16 }cm{sup −3}, and such a low electron concentration resulted in a low visible photoluminescence. UV illumination enhances the oxidation at low temperatures and decreases the concentration of the oxygen vacancies. The I-V characteristic showed a good rectification with a four-order magnitude difference in the forward and reverse currents at 2 V, and its linear and frequency independent C{sup −2}–V characteristic confirmed an abrupt pn junction. The photoresponse showed a visible blindness with a responsivity ratio of UV and visible light as high as 100. Such a visible-blind photoresponse was attributed to the optimum thickness of the SiO{sub 2} formed on the Si surface during the UV oxidation at 400 °C. A lower potential barrier to holes at the ZnO/SiO{sub 2} interface facilitates Fowler-Nordheim tunneling of the photo-generated holes during the UV illumination, while a higher potential barrier to electrons efficiently blocks transport of the photo-generated electrons to the ZnO during the visible light illumination. The presence of oxide resulted in a slow photoresponse to the turn-on and off of the UV light. A detailed analysis is presented to understand how the photo-generated carriers contribute step by step to the photocurrent. In addition to the slow photoresponse associated with the SiO{sub 2} interfacial layer, the decay of the photocurrent was found extremely slow after turn-off of the UV light. Such a slow decay of the photocurrent is referred to as a persistent photoconductivity, which is caused by metastable deep levels. It is hypothesized that Zn vacancies form such a deep level, and that the photo-generated electrons need to overcome a thermal-energy barrier for capture. The ZnO film by the UV oxidation at 400 °C was found

  20. Direct gap Ge1-ySny alloys: Fabrication and design of mid-IR photodiodes

    NASA Astrophysics Data System (ADS)

    Senaratne, C. L.; Wallace, P. M.; Gallagher, J. D.; Sims, P. E.; Kouvetakis, J.; Menéndez, J.

    2016-07-01

    Chemical vapor deposition methods were developed, using stoichiometric reactions of specialty Ge3H8 and SnD4 hydrides, to fabricate Ge1-ySny photodiodes with very high Sn concentrations in the 12%-16% range. A unique aspect of this approach is the compatible reactivity of the compounds at ultra-low temperatures, allowing efficient control and systematic tuning of the alloy composition beyond the direct gap threshold. This crucial property allows the formation of thick supersaturated layers with device-quality material properties. Diodes with composition up to 14% Sn were initially produced on Ge-buffered Si(100) featuring previously optimized n-Ge/i-Ge1-ySny/p-Ge1-zSnz type structures with a single defected interface. The devices exhibited sizable electroluminescence and good rectifying behavior as evidenced by the low dark currents in the I-V measurements. The formation of working diodes with higher Sn content up to 16% Sn was implemented by using more advanced n-Ge1-xSnx/i-Ge1-ySny/p-Ge1-zSnz architectures incorporating Ge1-xSnx intermediate layers (x ˜ 12% Sn) that served to mitigate the lattice mismatch with the Ge platform. This yielded fully coherent diode interfaces devoid of strain relaxation defects. The electrical measurements in this case revealed a sharp increase in reverse-bias dark currents by almost two orders of magnitude, in spite of the comparable crystallinity of the active layers. This observation is attributed to the enhancement of band-to-band tunneling when all the diode layers consist of direct gap materials and thus has implications for the design of light emitting diodes and lasers operating at desirable mid-IR wavelengths. Possible ways to engineer these diode characteristics and improve carrier confinement involve the incorporation of new barrier materials, in particular, ternary Ge1-x-ySixSny alloys. The possibility of achieving type-I structures using binary and ternary alloy combinations is discussed in detail, taking into account

  1. Numerical simulation of temperature field and thermal stress field in silicon-based positive-intrinsic-negative photodiode irradiated by multipulsed millisecond laser

    NASA Astrophysics Data System (ADS)

    Wei, Zhi; Jin, Guangyong; Tan, Yong; Zhao, Hongyu

    2015-10-01

    Laser induced morphological damage have been observed in silicon-based positive-intrinsic-negative photodiode. This paper adopted the methods of the theoretical calculation and finite element numerical simulation to model, then solved the temperature field and thermal stress field in silicon-based positive-intrinsic-negative photodiode irradiated by multipulsed millisecond laser, and researched the features and laws of the temperature field and thermal stress field. As for the thermal-mechanical problem of multipulsed millisecond laser irradiating silicon-based positive-intrinsic-negative photodiode, based on Fourier heat conduction and thermoelasticity theories, we established a two-dimensional axisymmetric mathematical model .Then adopted finite element method to simulate the transient temperature field and thermal stress field. The temperature dependences of the material parameters and the absorption coefficient were taken into account in the calculation. The results indicated that there was the heat accumulation effect when multipulsed millisecond laser irradiating silicon-based positive-intrinsic-negative photodiode. The morphological damage threshold were obtained numerically. The evolution of temperature at the central point of the top surface, the temperature distribution along the radial direction in the end of laser irradiation and the temperature distribution along the axial direction in the end of laser irradiation were considered. Meanwhile, the radial stress, hoop stress, axial stress on the top surface and the R=500μm axis were also considered. The results showed that the morphological damage threshold decreased with the increased of the pulse number. The results of this study have reference significance of researching the thermal and thermal stress effect evolution's features when multipulsed millisecond laser irradiating silicon-based positive-intrinsic-negative photodiode, then revealing the mechanism of interactions between millisecond laser and

  2. Hybrid Arrays for Chemical Sensing

    NASA Astrophysics Data System (ADS)

    Kramer, Kirsten E.; Rose-Pehrsson, Susan L.; Johnson, Kevin J.; Minor, Christian P.

    intelligence and robotics, all share the same essential data fusion challenges. The design of a hybrid sensor array should draw on this extended body of knowledge. In this chapter, various techniques for data preprocessing, feature extraction, feature selection, and modeling of sensor data will be introduced and illustrated with data fusion approaches that have been implemented in applications involving data from hybrid arrays. The example systems discussed in this chapter involve the development of prototype sensor networks for damage control event detection aboard US Navy vessels and the development of analysis algorithms to combine multiple sensing techniques for enhanced remote detection of unexploded ordnance (UXO) in both ground surveys and wide area assessments.

  3. Low dark current P-InAsSbP/n-InAs/N-InAsSbP/n+-InAs double heterostructure back-side illuminated photodiodes

    NASA Astrophysics Data System (ADS)

    Brunkov, P. N.; Il'inskaya, N. D.; Karandashev, S. A.; Karpukhina, N. G.; Lavrov, A. A.; Matveev, B. A.; Remennyi, M. A.; Stus', N. M.; Usikova, A. A.

    2016-05-01

    P-InAsSbP/n-InAs/N-InAsSbP/n+-InAs double heterostructure photodiodes with linear impurity distribution in the space charge region have been fabricated and studied. The photodiodes showed good perspectives for use in low temperature pyrometry as low dark current (8·10-6 A/cm2, Vbias = -0.5 V, 164 K) and background limited infrared photodetector (BLIP) regime starting from 150 K (2π field of view, D3.1μm ∗ = 1.4·1012 cm Hz1/2/W) have been demonstrated.

  4. A model for the trap-assisted tunneling mechanism in diffused n-p and implanted n(+)-p HgCdTe photodiodes

    NASA Technical Reports Server (NTRS)

    Rosenfeld, David; Bahir, Gad

    1992-01-01

    This paper presents a theoretical model for the trap-assisted tunneling process in diffused n-on-p and implanted n(+)-on-p HgCdTe photodiodes. The model describes the connection between the leakage current associated with the traps and the trap characteristics: concentration, energy level, and capture cross sections. It is observed that the above two types of diodes differ the voltage dependence of the trap-assisted tunneling current and dynamic resistance. The model takes this difference into account and offers an explanation of the phenomenon. The good fit between measured and calculated dc characteristics of the photodiodes supports the validity of the model.

  5. A compact, discrete CsI(Tl) scintillator/Si photodiode gamma camera for breast cancer imaging

    SciTech Connect

    Gruber, Gregory J.

    2000-12-01

    Recent clinical evaluations of scintimammography (radionuclide breast imaging) are promising and suggest that this modality may prove a valuable complement to X-ray mammography and traditional breast cancer detection and diagnosis techniques. Scintimammography, however, typically has difficulty revealing tumors that are less than 1 cm in diameter, are located in the medial part of the breast, or are located in the axillary nodes. These shortcomings may in part be due to the use of large, conventional Anger cameras not optimized for breast imaging. In this thesis I present compact single photon camera technology designed specifically for scintimammography which strives to alleviate some of these limitations by allowing better and closer access to sites of possible breast tumors. Specific applications are outlined. The design is modular, thus a camera of the desired size and geometry can be constructed from an array (or arrays) of individual modules and a parallel hole lead collimator for directional information. Each module consists of: (1) an array of 64 discrete, optically-isolated CsI(Tl) scintillator crystals 3 x 3 x 5 mm{sup 3} in size, (2) an array of 64 low-noise Si PIN photodiodes matched 1-to-1 to the scintillator crystals, (3) an application-specific integrated circuit (ASIC) that amplifies the 64 photodiode signals and selects the signal with the largest amplitude, and (4) connectors and hardware for interfacing the module with a motherboard, thereby allowing straightforward computer control of all individual modules within a camera.

  6. InGaAs PIN photodiodes on semi-insulating InP substrates with bandwidth exceeding 14 GHz

    NASA Astrophysics Data System (ADS)

    Wen-Jeng Ho; Ting-Arn Dai; Zuon-Ming Chuang; Wei Lin; Yuan-Kuang Tu; Meng-Chyi Wu

    1995-07-01

    The top-illuminated InGaAs PIN photodiodes have been fabricated from materials grown by metalorganic vapor phase epitaxy. Using the planar air-bridge approach and the selective etching technique, it can eliminate the significant bondpad capacitance which is present in conventional PIN photodiodes on conducting substrates. Besides, a self-aligned lift-off process is used for the n-contact recess and metallization. The anti-reflection coating devices have responsivity of 0.79 and 0.78 A/W at 1.3 and 1.55 μm, respectively. The fabricated devices with 30 μm photosensitive diameter have a very low dark current below 0.2 nA and low capacitance of 143 fF at -5V bias voltage. The 3-dB bandwidth of these devices is in excess of 14.8 GHz which is in good agreement with the calculated minority-carrier transit time through an absorbing layer thickness of 1.85 μm. The device performance reveals that these devices are potentially suitable for the applications in optoelectronic integrated circuits.

  7. A new approach to investigate leakage current mechanisms in infrared photodiodes from illuminated current-voltage characteristics

    SciTech Connect

    Gopal, Vishnu

    2014-08-28

    This paper presents a new approach to investigate leakage current mechanisms in infrared photodiodes from the illuminated current–voltage characteristics. The example of mid-wave mercury cadmium telluride photodiodes is presented to illustrate the new approach. The new method is suitable for evaluating diodes in an array environment as advance knowledge of any of the material or device parameters are not required. The thermal saturation current is estimated from the observed open circuit voltage and zero-bias current (photo-current) of the diode. The ohmic shunt resistance is estimated from the observed maximum dynamic impedance of the diode. The experimentally observed reverse bias diode current in excess of thermal current, photo-current, and ohmic shunt current is reported to be best described by an exponential function of the type, I{sub excess} = I{sub r0} + K{sub 1} exp (K{sub 2} V), where I{sub r0}, K{sub 1}, and K{sub 2} are fitting parameters and V is the applied bias voltage. Our investigations reveal a close link between the excess current and the sources of ohmic currents in the diode. Exponential growth of excess current with the applied bias voltage has been interpreted as an indication of soft breakdown of the diodes.

  8. CMOS integrated avalanche photodiodes and frequency-mixing optical sensor front end for portable NIR spectroscopy instruments.

    PubMed

    Yun, Ruida; Sthalekar, Chirag; Joyner, Valencia M

    2011-01-01

    This paper presents the design and measurement results of two avalanche photodiode structures (APDs) and a novel frequency-mixing transimpedance amplifier (TIA), which are key building blocks towards a monolithically integrated optical sensor front end for near-infrared (NIR) spectroscopy applications. Two different APD structures are fabricated in an unmodified 0.18 \\im CMOS process, one with a shallow trench isolation (STI) guard ring and the other with a P-well guard ring. The APDs are characterized in linear mode. The STI bounded APD demonstrates better performance and exhibits 3.78 A/W responsivity at a wavelength of 690 nm and bias voltage of 10.55 V. The frequency-mixing TIA (FM-TIA) employs a T-feedback network incorporating gate-controlled transistors for resistance modulation, enabling the simultaneous down-conversion and amplification of the high frequency modulated photodiode (PD) current. The TIA achieves 92 dS Ω conversion gain with 0.5 V modulating voltage. The measured IIP(3) is 10.6/M. The amplifier together with the 50 Ω output buffer draws 23 mA from a1.8 V power supply. PMID:22254238

  9. High-resolution mapping of the energy conversion efficiency of solar cells and silicon photodiodes in photovoltaic mode

    NASA Astrophysics Data System (ADS)

    Cemine, Vernon Julius; Sarmiento, Raymund; Blanca, Carlo Mar

    2008-11-01

    We demonstrate an optical technique to derive the two-dimensional energy conversion efficiency ( ηCE), fill factor (FF) and external quantum efficiency ( ηQE) distributions across the surface of photovoltaic devices. A compact, inexpensive optical-feedback laser diode microscope is constructed to acquire the confocal reflectance and efficiency maps enabling the observation of the local parametric behavior in silicon photodiodes in photovoltaic mode and single-junction solar cells. The ηCE and ηQE distributions are greatly influenced by local parasitic resistances that depend on laser irradiance. These parasitic resistances decrease the ηCE and ηQE values with distance from the contact electrode at high laser irradiance. The optical technique enables microscopic comparison of ηCE and ηQE within the pn-overlay region of the photodiode sample, revealing its optimization for photodetection rather than power generation. The technique also elucidates the decreasing local ηCE of the solar cell under intense irradiation.

  10. Filter-free integrated sensor array based on luminescence and absorbance measurements using ring-shaped organic photodiodes.

    PubMed

    Abel, Tobias; Sagmeister, Martin; Lamprecht, Bernhard; Kraker, Elke; Köstler, Stefan; Ungerböck, Birgit; Mayr, Torsten

    2012-12-01

    An optical waveguiding sensor array featuring monolithically integrated organic photodiodes as integrated photo-detector, which simplifies the readout system by minimizing the required parts, is presented. The necessity of any optical filters becomes redundant due to the proposed platform geometry, which discriminates between excitation light and sensing signal. The sensor array is capable of measuring luminescence or absorption, and both sensing geometries are based on the identical substrate. It is demonstrated that background light is virtually non-existent. All sensing and waveguide layers, as well as in- and out-coupling elements are assembled by conventional screen-printing techniques. Organic photodiodes are integrated by layer-by-layer vacuum deposition onto glass or common polymer foils. The universal and simple applicability of this sensor chip is demonstrated by sensing schemes for four different analytes. Relative humidity, oxygen, and carbon dioxide are measured in gas phase using luminescence-based sensor schemes; the latter two analytes are also measured by absorbance-based sensor schemes. Furthermore, oxygen and pH in aqueous media were enabled. The consistency of calibration characteristics extending over different sensor chips is verified. PMID:22706404

  11. Simulation for spectral response of solar-blind AlGaN based p-i-n photodiodes

    NASA Astrophysics Data System (ADS)

    Xue, Shiwei; Xu, Jintong; Li, Xiangyang

    2015-04-01

    In this article, we introduced how to build a physical model of refer to the device structure and parameters. Simulations for solar-blind AlGaN based p-i-n photodiodes spectral characteristics were conducted in use of Silvaco TCAD, where device structure and parameters are comprehensively considered. In simulation, the effects of polarization, Urbach tail, mobility, saturated velocities and lifetime in AlGaN device was considered. Especially, we focused on how the concentration-dependent Shockley-Read-Hall (SRH) recombination model affects simulation results. By simulating, we analyzed the effects in spectral response caused by TAUN0 and TAUP0, and got the values of TAUN0 and TAUP0 which can bring a result coincides with test results. After that, we changed their values and made the simulation results especially the part under 255 nm performed better. In conclusion, the spectral response between 200 nm and 320 nm of solar-blind AlGaN based p-i-n photodiodes were simulated and compared with test results. We also found that TAUN0 and TAUP0 have a large impact on spectral response of AlGaN material.

  12. Achieving a Linear Dose Rate Response in Pulse-Mode Silicon Photodiode Scintillation Detectors Over a Wide Range of Excitations

    NASA Astrophysics Data System (ADS)

    Carroll, Lewis

    2014-02-01

    We are developing a new dose calibrator for nuclear pharmacies that can measure radioactivity in a vial or syringe without handling it directly or removing it from its transport shield “pig”. The calibrator's detector comprises twin opposing scintillating crystals coupled to Si photodiodes and current-amplifying trans-resistance amplifiers. Such a scheme is inherently linear with respect to dose rate over a wide range of radiation intensities, but accuracy at low activity levels may be impaired, beyond the effects of meager photon statistics, by baseline fluctuation and drift inevitably present in high-gain, current-mode photodiode amplifiers. The work described here is motivated by our desire to enhance accuracy at low excitations while maintaining linearity at high excitations. Thus, we are also evaluating a novel “pulse-mode” analog signal processing scheme that employs a linear threshold discriminator to virtually eliminate baseline fluctuation and drift. We will show the results of a side-by-side comparison of current-mode versus pulse-mode signal processing schemes, including perturbing factors affecting linearity and accuracy at very low and very high excitations. Bench testing over a wide range of excitations is done using a Poisson random pulse generator plus an LED light source to simulate excitations up to ˜106 detected counts per second without the need to handle and store large amounts of radioactive material.

  13. Autocorrelation measurement of femtosecond laser pulses based on two-photon absorption in GaP photodiode

    SciTech Connect

    Chong, E. Z.; Watson, T. F.; Festy, F.

    2014-08-11

    Semiconductor materials which exhibit two-photon absorption characteristic within a spectral region of interest can be useful in building an ultra-compact interferometric autocorrelator. In this paper, we report on the evidence of a nonlinear absorption process in GaP photodiodes which was exploited to measure the temporal profile of femtosecond Ti:sapphire laser pulses with a tunable peak wavelength above 680 nm. The two-photon mediated conductivity measurements were performed at an average laser power of less than a few tenths of milliwatts. Its suitability as a single detector in a broadband autocorrelator setup was assessed by investigating the nonlinear spectral sensitivity bandwidth of a GaP photodiode. The highly favourable nonlinear response was found to cover the entire tuning range of our Ti:sapphire laser and can potentially be extended to wavelengths below 680 nm. We also demonstrated the flexibility of GaP in determining the optimum compensation value of the group delay dispersion required to restore the positively chirped pulses inherent in our experimental optical system to the shortest pulse width possible. With the rise in the popularity of nonlinear microscopy, the broad two-photon response of GaP and the simplicity of this technique can provide an alternative way of measuring the excitation laser pulse duration at the focal point of any microscopy systems.

  14. Evaluation of a photodiode array detector for the verification of peak-homogeneity in high-performance liquid chromatography.

    PubMed

    Chan, H K; Carr, G P

    1990-01-01

    Photodiode array liquid chromatography detectors are claimed to have the ability of evaluating the homogeneity of chromatographic peaks and this could provide a very powerful tool in support of method development. However, in pharmaceutical analysis, for this to be of practical value it must be capable of detecting inhomogeneities at low levels. In this paper, a test has been devised to challenge the sensitivity of instruments to this application. The test makes use of mixtures of the similar benzodiazepines temazepam and lormetazepam in a chromatographic system which does not separate them. One instrument has demonstrated the ability to detect levels of just 0.5% w/w of one benzodiazepine in the other. Statistical F-tests and t-tests have been used to demonstrate that non-homogeneities have been detected with a high level of confidence. It is concluded that photodiode array detectors have the potential to evaluate the homogeneity of chromatographic peaks with a high degree of sensitivity. However, most instruments do not realize this potential because their software does not make proper use of all the data available. PMID:2094426

  15. Impact of a New Highly Sensitive HgCdTe Avalanche Photodiode Detector on Receiver Performance for the CO2 Sounder Lidar for the ASCENDS Mission

    NASA Astrophysics Data System (ADS)

    Sun, X.; Abshire, J. B.

    2013-12-01

    NASA Goddard Space Flight Center (GSFC) is currently developing a CO2 lidar as a candidate for the NASA's planned ASCENDS mission under the support of Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP). As part of this work we have demonstrated new type of lower noise HgCdTe avalanche photodiode (APD) multi-element detector for the lidar receiver. This significantly improves the receiver sensitivity, lower the laser power, and reduce the receiver telescope size compared to InGaAs photomultiplier tubes (PMT) and APDs currently used. The HgCdTe APD arrays were designed and manufactured by DRS Technologies, Reconnaissance, Surveillance and Target Acquisition (RSTA) Division, which combines their mature HgCdTe APD detector in a hybrid package with a new custom cryogenic silicon preamplifier. The new detectors were specially designed for our airborne CO2 lidar and operate at ~ 77K inside a turn-key closed-cycle cooler. The detector has 80 μm square pixels in a 4x4 array, and >70% fill factor and was custom designed to match the optics of our airborne and eventually space-based CO2 lidar. The initial results of evaluating the detector at NASA GSFC showed the HgCdTe APD assembly has a quantum efficiency of ~90% near 1550-nm, >500 APD gain, 8-10 MHz electrical bandwidth, and an average noise equivalent power of <1fW/Hz1/2. The detector also has a much wider linear dynamic range than PMTs, since it operates in a linear analog mode and has variable gain. Given the wide range of surface reflectivities this is important for ASCENDS. The new detector also greatly improves our CO2 lidar's receiver sensitivity. Calculations show it enables us to reduce the laser transmitter power by half for the space borne instrument while staying with a conventional reasonably sized (~1.2 m) diameter receiver telescope. We will show analysis and laboratory test results of the CO2 lidar performance using a receiver with this new detector. We are also funded by NASA ESTO

  16. Hybrid mimics and hybrid vigor in Arabidopsis

    PubMed Central

    Wang, Li; Greaves, Ian K.; Groszmann, Michael; Wu, Li Min; Dennis, Elizabeth S.; Peacock, W. James

    2015-01-01

    F1 hybrids can outperform their parents in yield and vegetative biomass, features of hybrid vigor that form the basis of the hybrid seed industry. The yield advantage of the F1 is lost in the F2 and subsequent generations. In Arabidopsis, from F2 plants that have a F1-like phenotype, we have by recurrent selection produced pure breeding F5/F6 lines, hybrid mimics, in which the characteristics of the F1 hybrid are stabilized. These hybrid mimic lines, like the F1 hybrid, have larger leaves than the parent plant, and the leaves have increased photosynthetic cell numbers, and in some lines, increased size of cells, suggesting an increased supply of photosynthate. A comparison of the differentially expressed genes in the F1 hybrid with those of eight hybrid mimic lines identified metabolic pathways altered in both; these pathways include down-regulation of defense response pathways and altered abiotic response pathways. F6 hybrid mimic lines are mostly homozygous at each locus in the genome and yet retain the large F1-like phenotype. Many alleles in the F6 plants, when they are homozygous, have expression levels different to the level in the parent. We consider this altered expression to be a consequence of transregulation of genes from one parent by genes from the other parent. Transregulation could also arise from epigenetic modifications in the F1. The pure breeding hybrid mimics have been valuable in probing the mechanisms of hybrid vigor and may also prove to be useful hybrid vigor equivalents in agriculture. PMID:26283378

  17. Quasi-2D analysis of the effect of passivant on the performance of long-wavelength infrared HgCdTe photodiodes

    NASA Astrophysics Data System (ADS)

    Dhar, V.; Bhan, R. K.; Ashokan, R.; Kumar, V.

    1996-09-01

    The results of a quasi-two-dimensional model for calculating passivant-induced surface leakage currents due to band-to-band tunnelling in 0268-1242/11/9/010/img1 mercury cadmium telluride (MCT) 0268-1242/11/9/010/img2 photovoltaic (PV) diodes are presented. The object is to assess the effect of a fixed surface state charge density 0268-1242/11/9/010/img3 due to a passivant on the zero-bias resistance - area product 0268-1242/11/9/010/img4 for the technologically important case when surface state charges accumulate the MCT surface. Calculations are carried out to estimate the tolerable value of 0268-1242/11/9/010/img3 beyond which the 0268-1242/11/9/010/img4 of the MCT diode degrades. To the best of our knowledge, this is the first time that such a detailed calculation involving the acceptor concentration profile near the surface has been reported for long-wavelength IR (LWIR) MCT photodiodes. This calculation has been done numerically, and hence the depletion width (pinched near the surface), the electric field and the band-to-band tunnelling are calculated as a function of depth, layer by layer, from the passivant - semiconductor interface. The currents - diffusion, generation - recombination, band-to-band and trap-assisted tunnelling - have been calculated in each layer, and the zero-bias resistance - area product is determined for each mechanism. Hence, the resultant 0268-1242/11/9/010/img4 is calculated. The results are compared with the earlier step model of Bhan and Gopal (Semicond. Sci. Technol. 9 (1994) 289), which assumed a surface layer of constant concentration 0268-1242/11/9/010/img8. The present model indicates that for photodiodes with a cut-off wavelength of 0268-1242/11/9/010/img9 and an acceptor concentration 0268-1242/11/9/010/img10, operating at 77 K, a 0268-1242/11/9/010/img11 would degrade 0268-1242/11/9/010/img4 significantly. This value is insensitive to composition (in the LWIR). For an 0268-1242/11/9/010/img1 diode, the tolerable value of

  18. Hybridization and Selective Release of DNA Microarrays

    SciTech Connect

    Beer, N R; Baker, B; Piggott, T; Maberry, S; Hara, C M; DeOtte, J; Benett, W; Mukerjee, E; Dzenitis, J; Wheeler, E K

    2011-11-29

    DNA microarrays contain sequence specific probes arrayed in distinct spots numbering from 10,000 to over 1,000,000, depending on the platform. This tremendous degree of multiplexing gives microarrays great potential for environmental background sampling, broad-spectrum clinical monitoring, and continuous biological threat detection. In practice, their use in these applications is not common due to limited information content, long processing times, and high cost. The work focused on characterizing the phenomena of microarray hybridization and selective release that will allow these limitations to be addressed. This will revolutionize the ways that microarrays can be used for LLNL's Global Security missions. The goals of this project were two-fold: automated faster hybridizations and selective release of hybridized features. The first study area involves hybridization kinetics and mass-transfer effects. the standard hybridization protocol uses an overnight incubation to achieve the best possible signal for any sample type, as well as for convenience in manual processing. There is potential to significantly shorten this time based on better understanding and control of the rate-limiting processes and knowledge of the progress of the hybridization. In the hybridization work, a custom microarray flow cell was used to manipulate the chemical and thermal environment of the array and autonomously image the changes over time during hybridization. The second study area is selective release. Microarrays easily generate hybridization patterns and signatures, but there is still an unmet need for methodologies enabling rapid and selective analysis of these patterns and signatures. Detailed analysis of individual spots by subsequent sequencing could potentially yield significant information for rapidly mutating and emerging (or deliberately engineered) pathogens. In the selective release work, optical energy deposition with coherent light quickly provides the thermal energy to

  19. Characterization of a high-resolution hybrid DOI detector for a dedicated breast PET/CT scanner.

    PubMed

    Godinez, Felipe; Chaudhari, Abhijit J; Yang, Yongfeng; Farrell, Richard; Badawi, Ramsey D

    2012-06-01

    The aim of this study is to design and test a new high-resolution hybrid depth of interaction (DOI) detector for a dedicated breast PET/CT scanner. Two detectors have been designed and built. The completed detectors are based on a 14 × 14 array of 1.5 × 1.5 × 20 mm(3) unpolished lutetium orthosilicate scintillation crystals, with each element coated in a 50 μm layer of reflective material. The detector is read out from both ends using a position-sensitive photomultiplier tube (PSPMT) and a large active area (20 × 20 mm(2)) avalanche photodiode (APD) to enable acquisition of DOI information. Nuclear instrumentation modules were used to characterize the detectors' performances in terms of timing, intrinsic spatial resolution (ISR) and energy resolution, as well as DOI resolution with a dual-ended readout configuration. Measurements with the APD were performed at a temperature of 10 °C. All crystals were identified at all depths, even though the signal amplitude from the PSPMT decreases with depth away from it. We measured a timing resolution of 2.4 ns, and an average energy resolution of 19%. The mean ISR was measured to be 1.2 mm for crystals in the central row of the array for detectors in the face-to-face position. Two off-center positions were measured corresponding to 26° and 51° oblique photon incidence, and the mean ISR at these positions was 1.5 and 1.7 mm, respectively. The average DOI resolution across all crystals and depths was measured to be 2.9 mm (including the beam width of 0.6 mm). This detector design shows good promise as a high-resolution detector for a dedicated breast PET/CT scanner. PMID:22581109

  20. X-ray and charged particle detection with CsI(Tl) layer coupled to a-Si:H photodiode layers

    SciTech Connect

    Fujieda, I.; Cho, G.; Drewery, J.; Gee, T.; Jing, T.; Kaplan, S.N.; Perez-Mendez, V.; Wildermuth, D. ); Street, R.A. )

    1990-10-01

    A compact real-time X-ray and charged particle imager with digitized position output can built either by coupling a fast scintillator to a photodiode array or by forming one on a photodiode array directly. CsI(Tl) layers 100--1000{mu}m thick were evaporated on glass substrates from a crystal CsI(Tl). When coupled to a crystalline Si or amorphous silicon (a-Si:H) photodiode and exposed to calibrated X-ray pulses, their light yields and speed were found to be comparable to those of a crystal CsI(Tl). Single {beta} particle detection was demonstrated with this combination. The light spread inside evaporated CsI(Tl) was suppressed by its columnar structure. Scintillation detection gives much larger signals than direct X-ray detection due to the increased energy deposition in the detector material. Fabrication of monolithic type X-ray sensors consisting of CsI + a-Si:H photodiodes is discussed. 20 refs., 16 figs.