Science.gov

Sample records for front-illuminated photodiode array

  1. Analysis of crosstalk in front-illuminated InGaAs PIN hetero-junction photovoltaic infrared detector arrays

    NASA Astrophysics Data System (ADS)

    Li, Yongfu; Tang, Hengjing; Zhang, Kefeng; Li, Tao; Ning, Jinhua; Li, Xue; Gong, Haimei

    2009-07-01

    Here presented an experimental study on crosstalk in front illuminated planar and mesa-type InP/ InGaAs/ InP PIN hetero-junction photovoltaic infrared detector arrays. A scanning laser beam with an optical wavelength of 1310 nm coupled in a single-mode optical fiber placed within a few microns of the detector array surface was used to measure the crosstalk between the detector pixels. The crosstalk in the detector array varying with the distance between the incident laser spot and the measured pixel was shown. It is suggested that for the deep mesa-type arrays the dominating source of crosstalk is the light reflected from the detector substrate. And the dominating source of crosstalk that occurs in the planar type and shallow mesa type photovoltaic arrays is associated with photo-induced carries generated in the InGaAs absorption layer that diffuse laterally between neighbor pixels. These results gave out the possibility to optimize the detectors structures in order to reduce crosstalk.

  2. Characteristics of front-illuminated visible-blind UV photodetector based on GaN p-i-n photodiodes with high quantum efficiency

    NASA Astrophysics Data System (ADS)

    You, Da; Tang, Yingwen; Xu, Jintong; Gong, Haimei

    2006-02-01

    In this work, we reported the fabrication and characterization of an Al xGa 1-xN /GaN hetero-epitaxial front-illuminated visible-blind UV photodetector with very high external quantum efficiency. This device was grown on one side of polished sapphire substrate using a low-temperature AlN buffer layer created by three-pocket multi-wafer system metalorganic chemical vapor deposition (MOCVD) with a vertical reactor. This device consisted of a 2.5μm thick GaN n-layer, a 0.4μm thick GaN i-layer and Al 0.1Ga 0.9N "window layer", followed by a 10 nm GaN:Mg p+ contact layer. In order to investigate the effect of p- Al 0.1Ga 0.9N thickness on the characteristics of the photodetector, three samples only with different p-AlGaN thicknesses of 0.1μm and 0.15μm were fabricated. All of the device processing was completed using standard semiconductor processing techniques that included photolithography, metallization and etching. Compared the results of these three samples, the sample with 0.15μm thick p-AlGaN possesses the highest quantum efficiency and its zero-bias peak responsivity was found around 0.20A/W at 365 nm, corresponding to an external quantum efficiency of 85.6%. Moreover, this device exhibits a low dark current density of 3.16nA/cm2 at zero-bias.

  3. Integrated avalanche photodiode arrays

    DOEpatents

    Harmon, Eric S.

    2015-07-07

    The present disclosure includes devices for detecting photons, including avalanche photon detectors, arrays of such detectors, and circuits including such arrays. In some aspects, the detectors and arrays include a virtual beveled edge mesa structure surrounded by resistive material damaged by ion implantation and having side wall profiles that taper inwardly towards the top of the mesa structures, or towards the direction from which the ion implantation occurred. Other aspects are directed to masking and multiple implantation and/or annealing steps. Furthermore, methods for fabricating and using such devices, circuits and arrays are disclosed.

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. [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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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

  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. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. A discrete component low-noise preamplifier readout for a linear (1×16) SiC photodiode array

    NASA Astrophysics Data System (ADS)

    Kahle, Duncan; Aslam, Shahid; Herrero, Federico A.; Waczynski, Augustyn

    2016-09-01

    A compact, low-noise and inexpensive preamplifier circuit has been designed and fabricated to optimally readout a common cathode (1×16) channel 4H-SiC Schottky photodiode array for use in ultraviolet experiments. The readout uses an operational amplifier with 10 pF capacitor in the feedback loop in parallel with a low leakage switch for each of the channels. This circuit configuration allows for reiterative sample, integrate and reset. A sampling technique is given to remove Johnson noise, enabling a femtoampere level readout noise performance. Commercial-off-the-shelf acquisition electronics are used to digitize the preamplifier analog signals. The data logging acquisition electronics has a different integration circuit, which allows the bandwidth and gain to be independently adjusted. Using this readout, photoresponse measurements across the array between spectral wavelengths 200 nm and 370 nm are made to establish the array pixels external quantum efficiency, current responsivity and noise equivalent power.

  16. Ground calibration of CCD camera (XIS) with front-illuminated chips onboard Astro-E2

    NASA Astrophysics Data System (ADS)

    Nakajima, Hiroshi; Yamaguchi, Hiroya; Matsumoto, Hironori; Tsuru, Takeshi; Koyama, Katsuji; Kissel, Steve; LaMarr, Beverly; Bautz, Marshall W.

    2004-10-01

    We report on the results of the ground calibration of Astro-E2/XIS with front-illuminated (FI) chips. The sensors have basically the same performance as that of Astro-E/XIS. However, there are some improved points: (1) A 55Fe radio isotope is equipped on a door, and (2) a charge injection (CI)capability (described below) is added. The FI sensors have been calibrated at Kyoto University, Osaka University, and MIT. At Kyoto University we focus on the high energy range (>1.5 keV). We measured the gain, energy resolution, and quantum efficiency as the function of energy by using characteristic X-rays for each sensor. An energy resolution of 130 eV@5.9 keV (FWHM) and a quantum efficiency of 82%@6.4 keV are achieved. After XIS is launched, the Charge Transfer Inefficiency (CTI) increases due to the radiation damage by cosmic rays. Then XIS equips the CI capability to calibrate and compensate the increase of the CTI. In order to utilize the CI capability, the amount of charge injected into the CCDs is expected to be kept constant. The time variability of the amount of the injected charge is estimated.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. Linear mode photon counting from visible to MWIR with HgCdTe avalanche photodiode focal plane arrays

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Results of characterization data on linear mode photon counting (LMPC) HgCdTe electron-initiated avalanche photodiode (e-APD)focal plane arrays (FPA) are presented that reveal an improved understanding and the growing maturity of the technology. The first successful 2x8 LMPC FPA was fabricated in 2010 [1]. Since then a process validation lot of 2x8 arrays was fabricated. Five arrays from this lot were characterized that replicated the previous 2x8 LMPC array performance. In addition, it was unambiguously verified that readout integrated circuit (ROIC) glow was responsible for most of the false event rate (FER) of the 2010 array. The application of a single layer metal blocking layer between the ROIC and the detector array and optimization of the ROIC biases reduced the FER by an order of magnitude. Photon detection efficiencies (PDEs) of greater than 50% were routinely demonstrated across 5 arrays, with one array reaching a PDE of 70%. High resolution pixel-surface spot scans were performed and the junction diameters of the diodes were measured. The junction diameter was decreased from 31 μm to 25 μm resulting in a 2x increase in E-APD gain from 470 on the 2010 array to 1100 on one of the 2013 FPAs. Mean single photon signal to noise ratios of >12 were demonstrated at excess noise factors of 1.2-1.3. NASA Goddard Space Flight Center (GSFC) performed measurements on the delivered FPA that verified the PDE and FER data.

  2. 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.

  3. The Trace Analysis of DEET in Water using an On-line Preconcentration Column and Liquid Chromatography with UV Photodiode Array Detection

    EPA Science Inventory

    A method for the detection of trace levels of N,N-diethyl-m-toluamide (DEET) in water is discussed. The method utilizes an on-line preconcentration column in series with high performance liquid chromatography (HPLC) and UV photodiode array detection. DEET, a common insect repel...

  4. Microfluidic Biosensor Array with Integrated Poly(2,7-Carbazole)/Fullerene-Based Photodiodes for Rapid Multiplexed Detection of Pathogens

    PubMed Central

    Pires, Nuno Miguel Matos; Dong, Tao

    2013-01-01

    A multiplexed microfluidic biosensor made of poly(methylmethacrylate) (PMMA) was integrated into an array of organic blend heterojunction photodiodes (OPDs) for chemiluminescent detection of pathogens. Waterborne Escherichia coli O157:H7, Campylobacter jejuni and adenovirus were targeted in the PMMA chip, and detection of captured pathogens was conducted by poly(2,7-carbazole)/fullerene OPDs which showed a responsivity over 0.20 A/W at 425 nm. The limits of chemiluminescent detection were 5 × 105 cells/mL for E. coli, 1 × 105 cells/mL for C. jejuni, and 1 × 10−8 mg/mL for adenovirus. Parallel analysis for all three analytes in less than 35 min was demonstrated. Further recovery tests illustrated the potential of the integrated biosensor for detecting bacteria in real water samples. PMID:24287522

  5. Low-cost SWIR sensors: advancing the performance of ROIC-integrated colloidal quantum dot photodiode arrays

    NASA Astrophysics Data System (ADS)

    Klem, Ethan J. D.; Lewis, Jay; Gregory, Chris; Temple, Dorota; Wijewarnasuriya, Priyalal S.; Dhar, Nibir

    2014-06-01

    RTI has developed a novel photodiode technology based on solution-processed PbS colloidal quantum dots (CQD) capable of providing low-cost, high performance detection across the Vis-SWIR spectral range. The most significant advantages of the CQD technology are ease of fabrication, small pixel size, and extended wavelength range. The devices are fabricated directly onto the ROIC substrate at low temperatures compatible with CMOS, and arrays can be fabricated at wafer scale. We will discuss recent advances in device architecture and processing that result in measured dark currents of 15 nA/cm2 at room temperature and enhanced SWIR responsivity from the UV to ~1.7 μm, compare these results to InGaAs detectors, and present measurements of the CQD detectors temperature dependent dark current.

  6. 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.

  7. CMOS Geiger photodiode array with integrated signal processing for imaging of 2D objects using quantum dots

    NASA Astrophysics Data System (ADS)

    Stapels, Christopher J.; Lawrence, William G.; Gurjar, Rajan S.; Johnson, Erik B.; Christian, James F.

    2008-08-01

    Geiger-mode photodiodes (GPD) act as binary photon detectors that convert analog light intensity into digital pulses. Fabrication of arrays of GPD in a CMOS environment simplifies the integration of signal-processing electronics to enhance the performance and provide a low-cost detector-on-a-chip platform. Such an instrument facilitates imaging applications with extremely low light and confined volumes. High sensitivity reading of small samples enables twodimensional imaging of DNA arrays and for tracking single molecules, and observing their dynamic behavior. In this work, we describe the performance of a prototype imaging detector of GPD pixels, with integrated active quenching for use in imaging of 2D objects using fluorescent labels. We demonstrate the integration of on-chip memory and a parallel readout interface for an array of CMOS GPD pixels as progress toward an all-digital detector on a chip. We also describe advances in pixel-level signal processing and solid-state photomultiplier developments.

  8. A theoretical study of improved front-illuminated avalanche drift detectors

    NASA Astrophysics Data System (ADS)

    Liang, K.; Yuan, J.; Li, H. R.; Yang, R.; Han, D. J.

    2013-06-01

    In this study, two avalanche drift detector (ADD) concepts were theoretically examined. One was an improved detector with an avalanche photodiode (APD) collecting and double pn-junction drift configuration, and the other was a combination of an APD collecting and metal oxide semiconductor (MOS) drift structure. The feasibility of the devices was theoretically investigated by the ISE-TCAD program. ADD can be operated in either Geiger mode or linear mode. In the former case, the detector was found to be appropriate for a single photon avalanche detector with a large collection area. In the latter case, the detector was observed to be well suited to be coupled to a scintillator for gamma-ray detection. The improved ADDs are considered to have good performances in the short wavelength optical detection and in matching common scintillation crystals with more flexibility.

  9. Instrumentation: Photodiode Array Detectors in UV-VIS Spectroscopy. Part II.

    ERIC Educational Resources Information Center

    Jones, Dianna G.

    1985-01-01

    A previous part (Analytical Chemistry; v57 n9 p1057A) discussed the theoretical aspects of diode ultraviolet-visual (UV-VIS) spectroscopy. This part describes the applications of diode arrays in analytical chemistry, also considering spectroelectrochemistry, high performance liquid chromatography (HPLC), HPLC data processing, stopped flow, and…

  10. Enhanced photoresponse of conformal TiO{sub 2}/Ag nanorod array-based Schottky photodiodes fabricated via successive glancing angle and atomic layer deposition

    SciTech Connect

    Haider, Ali; Biyikli, Necmi; Cansizoglu, Hilal; Cansizoglu, Mehmet Fatih; Karabacak, Tansel; Okyay, Ali Kemal

    2015-01-01

    In this study, the authors demonstrate a proof of concept nanostructured photodiode fabrication method via successive glancing angle deposition (GLAD) and atomic layer deposition (ALD). The fabricated metal-semiconductor nanorod (NR) arrays offer enhanced photoresponse compared to conventional planar thin-film counterparts. Silver (Ag) metallic NR arrays were deposited on Ag-film/Si templates by utilizing GLAD. Subsequently, titanium dioxide (TiO{sub 2}) was deposited conformally on Ag NRs via ALD. Scanning electron microscopy studies confirmed the successful formation of vertically aligned Ag NRs deposited via GLAD and conformal deposition of TiO{sub 2} on Ag NRs via ALD. Following the growth of TiO{sub 2} on Ag NRs, aluminum metallic top contacts were formed to complete the fabrication of NR-based Schottky photodiodes. Nanostructured devices exhibited a photo response enhancement factor of 1.49 × 10{sup 2} under a reverse bias of 3 V.

  11. Determination of total phthalates in edible oils by high-performance liquid chromatography coupled with photodiode array detection.

    PubMed

    Xie, Qilong; Sun, Dekui; Han, Yangying; Jia, Litao; Hou, Bo; Liu, Shuhui; Li, Debao

    2016-03-01

    The previously reported procedure for the determination of the total phthalate in fatty food involved the extraction of phthalates using chloroform/methanol followed by the removal of the solvents before alkaline hydrolysis requiring 20 h and derivatization of phthalic acid. In this study, a phase-transfer catalyst (tetrabutylammonium chloride) was used in the liquid-liquid heterogeneous hydrolysis of phthalates in oil matrix shortening the reaction time to within 25 min. The resulting phthalic acid in the hydrolysate was extracted by a novel molecular complex based dispersive liquid-liquid microextraction method coupled with back-extraction before high-performance liquid chromatography coupled with photodiode array detection. Under the optimal experimental conditions, the linearity of the method was in the range of 0.5-12 nmol/g with the correlation coefficients (r) >0.997. The detection limit (S/N = 3) was 0.11 nmol/g. Intraday and interday repeatability values expressed as relative standard deviation were 3.9 and 7.1%, respectively. The recovery rates ranged from 82.4 to 99.0%. The developed method was successfully applied for the analysis of total phthalate in seven edible oils. PMID:26695378

  12. Fingerprint Analysis of Desmodium Triquetrum L. Based on Ultra Performance Liquid Chromatography with Photodiode Array Detector Combined with Chemometrics Methods.

    PubMed

    Zhang, Meiling; Zhao, Cui; Liang, Xianrui; Ying, Yin; Han, Bing; Yang, Bo; Jiang, Cheng

    2016-01-01

    A fingerprinting approach was developed by means of ultra high-performance liquid chromatography with photodiode array detector for the quality control of Desmodium triquetrum L., an herbal medicine widely used for clinical purposes. Ten batches of raw material samples of D. triquetrum were collected from different regions of China. All UPLC analyses were carried out on a Waters ACQUITY UPLC BEH shield RP18 column (2.1 × 50 mm, 1.7 µm particle size) at 60°C, with a gradient mobile phase composed of 0.1% aqueous formic acid and acetonitrile at a flow rate of 0.45 mL/min. The method validation results demonstrated the developed method possessing desirable reproducibility, efficiency, and allowing fingerprint analysis in one chromatographic run within 13 min. The quality assessment was achieved by using chemometrics methods including similarity analysis, hierarchical clustering analysis and principal component analysis. The developed method can be used for further quality control of D. triquetrum. PMID:26791345

  13. Determination of psychotropic phenylalkylamine derivatives in biological matrices by high-performance liquid chromatography with photodiode-array detection.

    PubMed

    Helmlin, H J; Brenneisen, R

    1992-02-28

    Several procedures using high-performance liquid chromatography with photodiode-array detection have been developed to create phytochemical and toxicological profiles of phenylalkylamine derivatives in biological samples (e.g. plant materials and urine). Mescaline-containing cactus samples were extracted with basic methanol, using methoxamine as internal standard; the extraction and clean-up of urine samples were performed on cation-exchange solid-phase extraction columns. The extracts were separated on a 3-micron ODS column with acetonitrile-water-phosphoric acid-hexylamine as the mobile phase. Peak detection was performed at 198 or 205 nm; peak identity and homogeneity were ascertained by on-line scanning of the UV spectra from 190 to 300 nm. The detection limit of phenylalkylamine derivatives in urine and cactus material was 0.026-0.056 micrograms/ml and 0.04 micrograms/mg, respectively. Following a single oral dose of 1.7 mg/kg methylenedioxymethylamphetamine (MDMA) the concentrations found in urine ranged from 1.48 to 5.05 micrograms/ml MDMA and 0.07-0.90 micrograms/ml methylenedioxyamphetamine (a metabolite of MDMA). The mescaline content of the cactus Trichocereus pachanoi varied between 1.09 and 23.75 micrograms/mg. PMID:1639916

  14. Free-space optics based sensor network design using angle-diversity photodiode arrays

    NASA Astrophysics Data System (ADS)

    Ghosh, Anjan K.; Kunta, Swathi; Verma, Pramode; Huck, Robert C.

    2010-08-01

    In this paper we describe a free-space optics (FSO) based mobile sensor network that is not subject to RF interference common to wireless sensor networks. FSO-based mobile sensor networks can potentially be used in applications where security of communication, including freedom from susceptibility to jamming, is important. The design of nodes containing multiple transceivers each composed of an LED and an angle-diversity array of identical photo detectors is discussed in this paper. Depending on the number of photodetectors in the array and the angular field of view of each photo detector we may obtain an increase in the signal to noise ratio of the overall optical communication system.

  15. A diffuse reflectance spectral imaging system for tumor margin assessment using custom annular photodiode arrays

    PubMed Central

    Dhar, Sulochana; Lo, Justin Y.; Palmer, Gregory M.; Brooke, Martin A.; Nichols, Brandon S.; Yu, Bing; Ramanujam, Nirmala; Jokerst, Nan M.

    2012-01-01

    Diffuse reflectance spectroscopy (DRS) is a well-established method to quantitatively distinguish between benign and cancerous tissue for tumor margin assessment. Current multipixel DRS margin assessment tools are bulky fiber-based probes that have limited scalability. Reported herein is a new approach to multipixel DRS probe design, which utilizes direct detection of the DRS signal by using optimized custom photodetectors in direct contact with the tissue. This first fiberless DRS imaging system for tumor margin assessment consists of a 4 × 4 array of annular silicon photodetectors and a constrained free-space light delivery tube optimized to deliver light across a 256 mm2 imaging area. This system has 4.5 mm spatial resolution. The signal-to-noise ratio measured for normal and malignant breast tissue-mimicking phantoms was 35 dB to 45 dB for λ = 470 nm to 600 nm. PMID:23243571

  16. Front-illuminated CCD with open pinned-phase region and two-phase transfer gate regions

    NASA Technical Reports Server (NTRS)

    Janesick, James R. (Inventor)

    1991-01-01

    A front-illuminated CCD of relative high quantum efficiency (QE) and high charge transfer efficiency (CTE) utilizes an open-phase region for receiving photons and two-phase gate regions (.phi..sub.1 and .phi..sub.2) for transferring electrons collected in one pixel to the next. The open-phase region is implanted with additional n-type elements (phosphorus) in order to increase the potential of the CCD channel in the open-phase region for collection of electrons and additionally implanted with concentrated and very shallow p-type elements (boron) to pin the surface of the n-channel in the open-phase region to OV, while gate region .phi..sub.1 and .phi..sub.2 are biased to -3.5V and driven to +10V by a two-phase transfer clock. The open pinned-phase (OPP) region thus permits two-phase transfer clocking and optimum reception of photons during the integration periods between transfer clock pulses.

  17. A linear photodiode array employed in a short range laser triangulation obstacle avoidance sensor. M.S. Thesis; [Martian roving vehicle sensor

    NASA Technical Reports Server (NTRS)

    Odenthal, J. P.

    1980-01-01

    An opto-electronic receiver incorporating a multi-element linear photodiode array as a component of a laser-triangulation rangefinder was developed as an obstacle avoidance sensor for a Martian roving vehicle. The detector can resolve the angle of laser return in 1.5 deg increments within a field of view of 30 deg and a range of five meters. A second receiver with a 1024 elements over 60 deg and a 3 meter range is also documented. Design criteria, circuit operation, schematics, experimental results and calibration procedures are discussed.

  18. Absolute calibration of a photodiode array with the use of the synchrotron radiation in the range of 1-10 keV

    NASA Astrophysics Data System (ADS)

    Beck, L.; Bizeuil, C.; Soullie, G.

    1995-02-01

    The silicon photodiode array Hamamatsu S3901 series (1024, 25 μm pixel) were primarily developed for the visible-UV spectral range, mainly for photon wavelengths between 200 and 1100 nm. By utilizing it without a quartz window, it is demonstrated that this sensor can be used for x rays, especially in the 1-10 keV range. Experimental measurements of the absolute detection efficiency of the photodiode array between 1.5 and 12 keV are presented. The experiments were performed on an x-ray tube-excited secondary targets and on the SB3 beamline at the Super ACO storage ring (LURE-Orsay). The measured spectral efficiency is compared with the results of a simple model calculation based on the data given in the Hamamatsu note. The simulation is in good agreement with the experimental data for a silicon active depth of 6 μm and a silicon dioxide passivation layer of 5 μm. The linearity is better than 1% and the spatial resolution is estimated to be 120 μm.

  19. Nuclear resonant scattering measurements on {sup 57}Fe by multichannel scaling with a 64-pixel silicon avalanche photodiode linear-array detector

    SciTech Connect

    Kishimoto, S. Haruki, R.; Mitsui, T.; Yoda, Y.; Taniguchi, T.; Shimazaki, S.; Ikeno, M.; Saito, M.; Tanaka, M.

    2014-11-15

    We developed a silicon avalanche photodiode (Si-APD) linear-array detector for use in nuclear resonant scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm{sup 2}) with a pixel pitch of 150 μm and depletion depth of 10 μm. An ultrafast frontend circuit allows the X-ray detector to obtain a high output rate of >10{sup 7} cps per pixel. High-performance integrated circuits achieve multichannel scaling over 1024 continuous time bins with a 1 ns resolution for each pixel without dead time. The multichannel scaling method enabled us to record a time spectrum of the 14.4 keV nuclear radiation at each pixel with a time resolution of 1.4 ns (FWHM). This method was successfully applied to nuclear forward scattering and nuclear small-angle scattering on {sup 57}Fe.

  20. 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.

  1. Simultaneous determination of 16 polycyclic aromatic hydrocarbons in reclaimed water using solid-phase extraction followed by ultra-performance convergence chromatography with photodiode array detection.

    PubMed

    Zhang, Yun; Xiao, Zhiyong; Lv, Surong; Du, Zhenxia; Liu, Xiaoxia

    2016-03-01

    A new fast and effective analysis method has been developed to simultaneously determine 16 polycyclic aromatic hydrocarbons in reclaimed water samples by ultra-performance convergence chromatography with photodiode array detection and solid-phase extraction. The parameters of ultra-performance convergence chromatography on the separation behaviors and the crucial condition of solid-phase extraction were investigated systematically. Under optimal conditions, the 16 polycyclic aromatic hydrocarbons could be separated within 4 min. The limits of detection and quantification were in the range of 0.4-4 and 1-10 μg/L in water, respectively. This approach has been applied to a real industrial wastewater treatment plant successfully. The results showed that polycyclic aromatic hydrocarbons were dramatically decreased after chemical treatment procedure, and the oxidation procedure was effective to remove trace polycyclic aromatic hydrocarbons. PMID:26663357

  2. 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.

  3. Developing Seedless Growth of ZnO Micro/Nanowire Arrays towards ZnO/FeS2/CuI P-I-N Photodiode Application

    NASA Astrophysics Data System (ADS)

    Yang, Zhi; Wang, Minqiang; Shukla, Sudhanshu; Zhu, Yue; Deng, Jianping; Ge, Hu; Wang, Xingzhi; Xiong, Qihua

    2015-06-01

    A seedless hydrothermal method is developed to grow high density and vertically aligned ZnO micro/nanowire arrays with low defect density on metal films under the saturated nutrition solution. In particular, the mechanism of seedless method is discussed here. A buffer layer can be confirmed by transmission electron microscopy (TEM), which may release the elastic strain between ZnO and substrate to achieve this highly mismatched heteroepitaxial structures. Based on ZnO micro/nanowire arrays with excellent wettability surface, we prepared ZnO-FeS2-CuI p-i-n photodiode by all-solution processed method with the high rectifying ratio of 197 at ±1 V. Under AM 1.5 condition, the Jsc of 0.5 mA/cm2, on-off current ratio of 371 and fast photoresponse at zero bias voltage were obtained. This good performance comes from excellent collection ability of photogenerated electrons and holes due to the increased depletion layer width for p-i-n structure. Finally, the high responsivity around 900 nm shows the potential as near infrared photodetectors applications.

  4. Developing Seedless Growth of ZnO Micro/Nanowire Arrays towards ZnO/FeS2/CuI P-I-N Photodiode Application

    PubMed Central

    Yang, Zhi; Wang, Minqiang; Shukla, Sudhanshu; Zhu, Yue; Deng, Jianping; Ge, Hu; Wang, Xingzhi; Xiong, Qihua

    2015-01-01

    A seedless hydrothermal method is developed to grow high density and vertically aligned ZnO micro/nanowire arrays with low defect density on metal films under the saturated nutrition solution. In particular, the mechanism of seedless method is discussed here. A buffer layer can be confirmed by transmission electron microscopy (TEM), which may release the elastic strain between ZnO and substrate to achieve this highly mismatched heteroepitaxial structures. Based on ZnO micro/nanowire arrays with excellent wettability surface, we prepared ZnO-FeS2-CuI p-i-n photodiode by all-solution processed method with the high rectifying ratio of 197 at ±1 V. Under AM 1.5 condition, the Jsc of 0.5 mA/cm2, on-off current ratio of 371 and fast photoresponse at zero bias voltage were obtained. This good performance comes from excellent collection ability of photogenerated electrons and holes due to the increased depletion layer width for p-i-n structure. Finally, the high responsivity around 900 nm shows the potential as near infrared photodetectors applications. PMID:26077658

  5. 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

  6. 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

  7. IDENTIFICATION AND QUANTITATION OF ALKYLATED NUCLEOBASIS BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH UV PHOTODIODE ARRAY DETECTION

    EPA Science Inventory

    The application of UV diode array detection in high-performance liquid chromatographic (HPLC) identification and quantitation of several classes of synthetic and commercially available alkylated nucleobases is investigated. uantitative spectral overlays of these compounds to meth...

  8. High efficiency n-Si/ p-Cu2O core-shell nanowires photodiode prepared by atomic layer deposition of Cu2O on well-ordered Si nanowires array

    NASA Astrophysics Data System (ADS)

    Kim, Hangil; Kim, Soo-Hyun; Ko, Kyung Yong; Kim, Hyungjun; Kim, Jaehoon; Oh, Jihun; Lee, Han-Bo-Ram

    2016-05-01

    A highly efficient n-Si/ p-Cu2O core-shell (C-S) nanowire (NW) photodiode was fabricated using Cu2O grown by atomic layer deposition (ALD) on a well-ordered Si NW array. Ordered Si nanowires arrays were fabricated by nano-sphere lithography to pattern metal catalysts for the metal-assisted etching of silicon, resulting in a Si NW arrays with a good arrangement, smooth surface and small diameter distribution. The ALD-Cu2O thin films were grown using a new non-fluorinated Cu precursor, bis(1-dimethylamino-2-methyl-2-butoxy)copper (C14H32N2O2Cu), and water vapor (H2O) at 140°C. Transmission electron microscopy equipped with an energy dispersive spectrometer confirmed that p-Cu2O thin films had been coated over arrayed Si NWs with a diameter of 150 nm (aspect ratio of ˜7.6). The C-S NW photodiode exhibited more sensitive photodetection performance under ultraviolet illumination as well as an enhanced photocurrent density in the forward biasing region than the planar structure diode. The superior performance of C-S NWs photodiode was explained by the lower reflectance of light and the effective carrier separation and collection originating from the C-S NWs structure. [Figure not available: see fulltext.

  9. Development of a Validated HPLC/Photodiode Array Method for the Determination of Isomenthone in the Aerial Parts of Ziziphora tenuior L.

    PubMed Central

    Ghassemi, Nasrollah; Ghanadian, Mustafa; Ghaemmaghami, Lili; Kiani, Haran

    2013-01-01

    Background Ziziphora tenuior L. known as Kakuti in Persian, is used in traditional medicine for fever, dysentery, uterus infection and as an analgesic. It is used also in the treatment of gastrointestinal disorders as carminative, or remedy of diarrhea or nausea. Major components of plant essential oil including pulegone, isomenthone, thymol, menthone, and piperitone are suggested to be responsible for the mentioned medicinal properties. Objectives In the present study, a normal high performance liquid chromatography (HPLC)/photodiode array validated method for quantification of isomenthone, one of the major constituents of Ziziphora, was established for the first time with a simple, rapid and accurate method. Materials and Methods HPLC analysis was done on a Waters system, equipped with 515 HPLC pump and waters 2996 photodiode array detector. The column was a Nova-Pak Silica (3.9 × 150 mm), and Empower software was used for the determination of the compounds and processing the data. The method was validated according to USP 32 requirements. Results A selective method for the resolution of isomenthone from two nearest peaks, thymol, and carvacrol was obtained with gradient system of hexane (A), and hexane: ethyl acetate (9:1) (B), starting with A: B (100:0) for 2 minutes, then 0−20% B in 5 minutes, A:B (80:20) for 5 minutes, then 20-30% B in 3 minutes, 30-100% B for 5 minutes, A:B (0:100) for 4 minutes following with equilibrating for 10 minutes. The flow rate was 1 mL/min at 22˚C and the injection volume for the standards and the samples was 20 μL. The retention time for isomenthone was found to be 7.45 minutes. The regression equation was y = 143235x - 2433 with the correlation co-factor R2 = 0.9992 and the percent recovery of 65.4 ± 3.85%. The sample obtained from 5 g of Z. teniour dried powder in 6 mL extract was standardized to contain 1.14 ± 0.030 μL/mL isomenthone which is equivalent to % 1.37 μL/g of the dried powdered plant. Limit of detection

  10. Determination of nitroaromatic explosives and their degradation products in unsaturated-zone water samples by high-performance liquid chromatography with photodiode-array, mass spectrometric, and tandem mass spectrometric detection

    USGS Publications Warehouse

    Gates, Paul M.; Furlong, E.T.; Dorsey, T.F.; Burkhardt, M.R.

    1996-01-01

    Mass spectrometry and tandem mass spectrometry, coupled by a thermospray interface to a high-performance liguid chromatography system and equipped with a photodiode array detector, were used to determine the presence of nitroaromatic explosives and their degradation products in USA unsaturated-zone water samples. Using this approach, the lower limits of quantitation for explosives determined by mass spectrometry in this study typically ranged from 10 to 100 ng/l.

  11. Applicability of accelerated solvent extraction for synthetic colorants analysis in meat products with ultrahigh performance liquid chromatography-photodiode array detection.

    PubMed

    Liao, Qie Gen; Li, Wei Hong; Luo, Lin Guang

    2012-02-24

    Accelerated solvent extraction (ASE) coupled with ultrahigh performance liquid chromatography (UHPLC) with photodiode array detection (PDA) has been used for the quantitative determination of synthetic colorants in meat products. Samples were extracted with ethanol-water-ammonia with a ratio of 75:24:1 (v/v/v) using ASE instrument at 85°C. As a result, all the colorants in meat products were separated using an optimized gradient elution within 3.5 min. Detection and quantification limits of synthetic colorants were in the ranges of 0.01-0.02 mg kg(-1) and 0.05 mg kg(-1), respectively. The intra-day and inter-day precision of the synthetic colorants were ranged between 1.7% (E123) to 5.2% (E124) and 3.2% (E124) to 6.0% (E129), respectively. The intra-day and inter-day recoveries of the synthetic colorants were ranged between 76.9% (E124) to 84.9% (E102) and 76.3% (E124) to 84.3% (E127), respectively. The method has been applied for the determination of seven synthetic colorants in meat products. PMID:22284887

  12. 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

  13. Determination of nitrofurans in animal feeds by liquid chromatography-UV photodiode array detection and liquid chromatography-ionspray tandem mass spectrometry.

    PubMed

    Barbosa, Jorge; Moura, Sara; Barbosa, Rita; Ramos, Fernando; da Silveira, Maria Irene Noronha

    2007-03-14

    Within the EU, the use of nitrofurans is prohibited in food production animals. For this reason detection of these compounds in feedingstuffs, at whatever limit, constitutes an offence under EU legislation. This detection generally involves the use of analytical methods with limits of quantification lowers than 1 mg kg(-1). These procedures are unsuitable for the detection and confirmation of trace amounts of nitrofurans in feedingstuffs due to contamination. It is well known that very low concentrations of these compounds can be the source of residues of nitrofuran metabolites in meat and other edible products obtained from animals consuming the contaminated feed. The present multi-compound method was capable of measuring very low concentrations of nitrofurantoin (NFT), nitrofurazone (NFZ), furazolidone (FZD) and furaltadone (FTD) in animal feed using nifuroxazide (NXZ) as internal standard. Following ethyl acetate extraction at mild alkaline conditions and purification on NH2 column, the nitrofurans are determined using liquid chromatography with photodiode-array detection (LC-DAD). It was observed a CCalpha ranged from 50 to 100 microg kg(-1). The liquid chromatography-tandem mass spectrometric (LC-MS/MS) procedure was used to confirm the identity of the suspected presence of any of the nitrofuran compounds. PMID:17386735

  14. Structural characterization and identification of flavonoid aglycones in three Glycyrrhiza species by liquid chromatography with photodiode array detection and quadrupole time-of-flight mass spectrometry.

    PubMed

    Fang, Shiqi; Qu, Qiyang; Zheng, Yunfeng; Zhong, Huanhuan; Shan, Chenxiao; Wang, Fang; Li, Cunyu; Peng, Guoping

    2016-06-01

    Flavonoids, including flavones, isoflavones, flavanones, chalcones, and isoflavans, have long been recognized as the main active ingredients in licorice. A method combining liquid chromatography with photodiode array detection and quadrupole time-of-flight mass spectrometry was developed to characterize components in three Glycyrrhiza species, and to expound the characteristic fragmentation behaviors in the positive ion mode. Based on the fragmentation patterns of reference compounds, a total of 39 compounds, including 37 flavonoid aglycones and two coumestans, were identified or tentatively identified. Besides, some common features, such as H2 O, CO, and CH2 O2 losses, together with retro-Diels-Alder fragmentation, were observed in these compounds. Furthermore, diagnostic fragmentations of C-ring cleavages and UV absorption on the skeleton groups were observed to structurally characterize flavonoid aglycones. In addition, typical losses of different substituent groups were detected: Neutral losses of 56 (C4 H8 ) and 68 Da (C5 H8 ) were yielded from a prenyl chain; neutral losses of 42 (C3 H6 ), 54 (C4 H6 ), and 70 Da (C4 H6 O) were generated by a pyran ring. Particularly, neutral losses of 18 (H2 O), 16 (CH4 ), 112 (C8 H16 ), and 98 Da (C7 H14 ) predicted a hydroxyl, a methoxyl, double prenyl chains, and a prenyl chain with a pyran ring, respectively. PMID:27062005

  15. Measuring levels of biogenic amines and their metabolites in rat brain tissue using high-performance liquid chromatography with photodiode array detection.

    PubMed

    Gu, Min-Jung; Jeon, Ji-Hyun; Oh, Myung Sook; Hong, Seon-Pyo

    2016-01-01

    We developed a method to detect biogenic amines and their metabolites in rat brain tissue using simultaneous high-performance liquid chromatography and a photodiode array detection. Measurements were made using a Hypersil Gold C-18 column (250 × 2.1 mm, 5 µm). The mobile phase was 5 mM perchloric acid containing 5 % acetonitrile. The correlation coefficient was 0.9995-0.9999. LODs (S/N = 3) and LOQs (S/N = 10) were as follows: dopamine 0.4 and 1.3 pg, 3, 4-dihydroxyphenylacetic acid 8.4 and 28.0 pg, serotonin 0.4 and 1.3 pg, 5-hydroxyindolacetic acid 3.4 and 11.3 pg, and homovanillic acid 8.4 and 28.0 pg. This method does not require derivatization steps, and is more sensitive than the widely used HPLC-UV method. PMID:26463700

  16. 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.

  17. 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

  18. A multivariate study of the performance of an ultrasound-assisted madder dyes extraction and characterization by liquid chromatography-photodiode array detection.

    PubMed

    Cuoco, Guillaume; Mathe, Carole; Archier, Paul; Chemat, Farid; Vieillescazes, Cathy

    2009-01-01

    An extraction method of madder (Rubia tinctorum) roots dyes is established and optimized to obtain the original chemical composition. A central composite design (CCD) was developed to specify the importance of the three major factors studied (time, temperature and solvent composition) affecting the ultrasound-assisted extraction of this matrix. A preliminary granulometric study of madder roots is realized in the aim to determine the optimal particles size corresponding to the best ultrasound effects. A comparison with the classical extraction method of madder dyes by reflux is described. The identification of the constituents of R. tinctorum is carried out by liquid chromatography coupled with a photodiode array detector (LC-PDA). Anthraquinonic aglycone and heterosidic dyes compounds are characterized by retention time and UV spectrum: alizarin (1,2-dihydroxyanthraquinone), purpurin (1,2,4-trihydroxyanthraquinone), lucidin (1,3-dihydroxy-2-hydroxymethylanthraquinone), rubiadin (1,3-dihydroxy-2-methylanthraquinone), xanthopurpurin (1,3-dihydroxyanthraquinone), pseudopurpurin (1,2,4-trihydroxy-3-carboxyanthraquinone), lucidin primeveroside, ruberythric acid (alizarin primeveroside), galiosin (pseudopurpurin primeveroside) and rubiadin primeveroside. The optimal experimental conditions are 18min, 36 degrees C and 37/63 MeOH/H(2)O (v/v). PMID:18617432

  19. Detection by coupled LC-photodiode array detection and high-resolution Orbitrap MS of dimethyl and diethyl yellow dyes used illegally in processed soymilk curd.

    PubMed

    Fang, Mingchih; Tsai, Chia-Fen; Kuo, Ching-Hao; Cheng, Hwei-Fang

    2015-01-01

    An efficient non-target dye-screening system consisting of a liquid chromatography photodiode array coupled with a high-resolution mass spectrometer (HRMS) is described. Visible absorption spectroscopy assisted in locating the peak of an unknown dye in HRMS chromatograms which allowed the accurate molecular weight of the unknown to be obtained. In a study of the adulteration of processed soymilk curd (tofu) with dimethyl yellow, an unexpected unknown dye was discovered. The compound was further purified by gel permeation chromatography and identified by HRMS and proton nuclear magnetic resonance (NMR) as diethyl yellow (solvent yellow 56). This is the first time that diethyl yellow has been reported in foods. The authentic diethyl yellow was then purchased and used as a quantitative standard. Tofu products and their ingredients associated with tofu processing were surveyed. Analysis showed the source of diethyl yellow could be traced to emulsifiers used as ingredient in tofu products. Surveillance work found the concentrations of diethyl yellow ranged from several μg kg(-1) (ppb) in the tofu products to up to hundreds of mg kg(-1) (ppm) in the emulsifiers. PMID:26076046

  20. Quantitative determination of usnic acid in Usnea lichen and its products by reversed-phase liquid chromatography with photodiode array detector.

    PubMed

    Ji, Xiuhong; Khan, Ikhlas A

    2005-01-01

    Usnic acid, a lichen substance, has a wide range of pharmaceutical applications, including antibiotic, antimycotic, antifeedant, antitubercular, antitumor, and analgesic activities. Some products containing usnic acid are marketed as weight control supplements; however, hepatotoxicity and acute liver failures were reported as severe side effects. The usnic acid content present in the plant materials and market products was analyzed by reversed-phase high-pressure liquid chromatography with a photodiode array detector at 233 nm. A Waters XTerra RP18 (150 x 4.6 mm; 5 microm particle size) column was the stationary phase; mobile phase was aqueous 0.1% acetic acid and acetonitrile gradient at flow rate of 1.0 mL/min. The temperature was held constant at 30 degrees C. The retention time of usnic acid was approximately 13.3 min. Acetone extraction of the samples took place with sonication. The precision of the method was confirmed by a standard deviation below 3.0% (n=3) and usnic acid recovery was 99.0%. Limit of detection was 0.4 microg/mL and the response was linear from 1.4 to 570.0 microg/mL with a correlation coefficient (R2) of 0.9991. The content of usnic acid in 4 raw materials and 22 finished products was analyzed. PMID:16385974

  1. A fully automated system for analysis of pesticides in water: on-line extraction followed by liquid chromatography-tandem photodiode array/postcolumn derivatization/fluorescence detection.

    PubMed

    Patsias, J; Papadopoulou-Mourkidou, E

    1999-01-01

    A fully automated system for on-line solid phase extraction (SPE) followed by high-performance liquid chromatography (HPLC) with tandem detection with a photodiode array detector and a fluorescence detector (after postcolumn derivatization) was developed for analysis of many chemical classes of pesticides and their major conversion products in aquatic systems. An automated on-line-SPE system (Prospekt) operated with reversed-phase cartridges (PRP-1) extracts analytes from 100 mL acidified (pH = 3) filtered water sample. On-line HPLC analysis is performed with a 15 cm C18 analytical column eluted with a mobile phase of phosphate (pH = 3)-acetonitrile in 25 min linear gradient mode. Solutes are detected by tandem diode array/derivatization/fluorescence detection. The system is controlled and monitored by a single computer operated with Millenium software. Recoveries of most analytes in samples fortified at 1 microgram/L are > 90%, with relative standard deviation values of < 5%. For a few very polar analytes, mostly N-methylcarbamoyloximes (i.e., aldicarb sulfone, methomyl, and oxamyl), recoveries are < 20%. However, for these compounds, as well as for the rest of the N-methylcarbamates except for aldicarb sulfoxide and butoxycarboxim, the limits of detection (LODs) are 0.005-0.05 microgram/L. LODs for aldicarb sulfoxide and butoxycarboxim are 0.2 and 0.1 microgram, respectively. LODs for the rest of the analytes except 4-nitrophenol, bentazone, captan, decamethrin, and MCPA are 0.05-0.1 microgram/L. LODs for the latter compounds are 0.2-1.0 microgram/L. The system can be operated unattended. PMID:10444834

  2. Influence of nonpolar substances on the extraction efficiency of six alkaloids in Zoagumhwan investigated by ultra performance liquid chromatography and photodiode array detection.

    PubMed

    Zhao, Yanling; Jia, Lei; Yang, Hongbo; Wang, Jiabo; Zhang, Ping; Li, Ruisheng; Gong, Man; Luo, Shengqiang; Liu, Shijing; Xiao, Xiaohe

    2012-01-01

    A reverse phase ultra performance liquid chromatography and photodiode array (UPLC-PDA) detection method was established for the determination of six alkaloids in Zoagumhwan (ZGW), and further for investigating the influence of nonpolar substances on the extraction efficiency of these alkaloids. The method was based on a BEH C(18) (50 mm × 2.1 mm, 1.7 μm) column and mobile phase of aqueous phosphoric acid and acetonitrile including 0.05% buffer solution under gradient elution. ZGW samples of ZGW I, II, III and IV were obtained and prepared by pre-processing the crude materials of Coptidis rhizoma and Evodiae fructus using four technologies, namely direct water decoction, removal of nonpolar substances in Evodiae fructus by supercritical fluid extraction (SFE), removal of nonpolar substances in ZGW by SFE and removal of nonpolar substances in ZGW by steam distillation. The developed and validated UPLC-PDA method was precise, accurate and sensitive enough based on the facts that the six alkaloids showed good regression (r > 0.9998), the limit of detections and quantifications for six alkaloids were less than 28.8 and 94.5 ng/mL, respectively, and the recovery was in the range of 98.56%-103.24%. The sequence of the total contents of six alkaloids in these samples was ZGW II > ZGW IV > ZGW III > ZGW I. ZGW II, in which nonpolar substances, including essential oils, were firstly removed from Evodiae fructus by SFE, had the highest content of the total alkaloids, indicating that extraction efficiency of the total alkaloids could be remarkably increased after Evodiae fructus being extracted by SFE. PMID:23174900

  3. 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)

  4. Characteristics of Monolithically Integrated InGaAs Active Pixel Imager Array

    NASA Technical Reports Server (NTRS)

    Kim, Q.; Cunningham, T. J.; Pain, B.; Lange, M. J.; Olsen, G. H.

    2000-01-01

    Switching and amplifying characteristics of a newly developed monolithic InGaAs Active Pixel Imager Array are presented. The sensor array is fabricated from InGaAs material epitaxially deposited on an InP substrate. It consists of an InGaAs photodiode connected to InP depletion-mode junction field effect transistors (JFETs) for low leakage, low power, and fast control of circuit signal amplifying, buffering, selection, and reset. This monolithically integrated active pixel sensor configuration eliminates the need for hybridization with silicon multiplexer. In addition, the configuration allows the sensor to be front illuminated, making it sensitive to visible as well as near infrared signal radiation. Adapting the existing 1.55 micrometer fiber optical communication technology, this integration will be an ideal system of optoelectronic integration for dual band (Visible/IR) applications near room temperature, for use in atmospheric gas sensing in space, and for target identification on earth. In this paper, two different types of small 4 x 1 test arrays will be described. The effectiveness of switching and amplifying circuits will be discussed in terms of circuit effectiveness (leakage, operating frequency, and temperature) in preparation for the second phase demonstration of integrated, two-dimensional monolithic InGaAs active pixel sensor arrays for applications in transportable shipboard surveillance, night vision, and emission spectroscopy.

  5. 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.

  6. Electro-Optical Characteristics of P+n In0.53Ga0.47As Hetero-Junction Photodiodes in Large Format Dense Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    DeWames, R.; Littleton, R.; Witte, K.; Wichman, A.; Bellotti, E.; Pellegrino, J.

    2015-08-01

    This paper is concerned with focal plane array (FPA) data and use of analytical and three-dimensional numerical simulation methods to determine the physical effects and processes limiting performance. For shallow homojunction P+n designs the temperature dependence of dark current for T < 300 K depends on the intrinsic carrier concentration of the In0.53Ga0.47As material, implying that the dominant dark currents are generation and recombination (G-R) currents originating in the depletion regions of the double layer planar heterostructure (DLPH) photodiode. In the analytical model differences from bulk G-R behavior are modeled with a G-R like perimeter-dependent shunt current conjectured to originate at the InP/InGaAs interface. In this description the fitting property is the effective conductivity, σ eff( T), in mho cm-1. Variation in the data suggests σ eff (300 K) values of 1.2 × 10-11-4.6 × 10-11 mho cm-1). Substrate removal extends the quantum efficiency (QE) spectral band into the visible region. However, dead-layer effects limit the QE to 10% at a wavelength of 0.5 μm. For starlight-no moon illumination conditions, the signal-to-noise ratio is estimated to be 50 at an operating temperature of 300 K. A major result of the 3D numerical simulation of the device is the prediction of a perimeter G-R current not associated with the properties of the metallurgical interface. Another is the prediction that for a junction positioned in the larger band gap InP cap layer the QE is bias-dependent and that a relatively large reverse bias ≥0.9 V is needed for the QE to saturate to the shallow homojunction value. At this higher bias the dark current is larger than the shallow homojunction value. The 3D numerical model and the analytical model agree in predicting and explaining the measured radiatively limited diffusion current originating at the n-side of the junction. The calculations of the area-dependent G-R current for the condition studied are also in agreement

  7. 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.

  8. Extending the Astronomical Application of Photon Counting HgCdTe Linear Avalanche Photo-Diode Arrays to Low Background Space Observations.

    NASA Astrophysics Data System (ADS)

    Hall, Donald

    The high quantum efficiency and very low dark current, together with the ability to set the wavelength cutoff from one to far beyond 5.5 microns, of large format HAWAII HgCdTe arrays have already made them the workhorse for NASA space astronomy (and related) observations in the 1 to 5.5 micron infrared. They have performed outstandingly on Hubble Wide Field Camera 3 and WISE (and also Deep Impact/EPOXI and OCO-2) and are crucial to the two major NASA Astrophysics missions, JWST and WFIRST, and to Euclid. The proposed investigation seeks to extend these benefits to the most demanding observations those that seek to wring information from only a few photons (starved due to either the intrinsic faintness of the source or the need for high spectral or time resolution) or to discriminate a weak signature against a bright source. We will characterize, and optimize for space astronomy observations, the unique linear avalanche properties of HgCdTe photo-diodes (HgCdTe L-APDs) that allow noiseless (i.e. faithfully preserves the Poisson statistics of the incoming photons) avalanche multiplication of individual photo-electrons. 2.5 micron HgCdTe L-APD technology, developed for infrared eye-safe LIDAR and range gated imaging, is already benefiting infrared wavefront sensing for ground based adaptive optics. In HgCdTe the L-APD gain and the onset voltage for tunneling current are exponential functions of bandgap while also varying with cryogenic operating temperature. The unique HgCdTe bandgap engineering that allows tuning of the cutoff wavelength can be used to critically improve avalanche performance for specific applications. We will thoroughly evaluate avalanche performance at several representative bandgaps so as to allow model prediction of performance over the critical 1 to 5 micron spectral interval. The proposed investigation will hybridize modest 32x32 arrays of HgCdTe L-APDs to photon counting readouts already developed under another award and characterize their

  9. 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.

  10. Photodiodes based on self-assembled GeSi/Si(001) nanoisland arrays grown by the combined sublimation molecular-beam epitaxy of silicon and vapor-phase epitaxy of germanium

    SciTech Connect

    Filatov, D. O.; Gorshkov, A. P.; Volkova, N. S.; Guseinov, D. V.; Alyabina, N. A.; Ivanova, M. M.; Chalkov, V. Yu.; Denisov, S. A.; Shengurov, V. G.

    2015-03-15

    We investigate the photosensitivity spectra of photodiodes based on Si p-i-n structures with single-layered and multilayer self-assembled GeSi/Si(001) nanoisland arrays in the i region, which are grown using a technique combining Si molecular-beam epitaxy and Ge vapor-phase epitaxy, in dependence on the temperature, diode bias, and GeSi nanoisland parameters. We show that the temperature and field dependences of the diode photosensitivity in the spectral range of the interband optical absorption in GeSi nanoislands are determined by the ratio between the rate of emission of photoexcited holes from the nanoislands and the rate of the recombination of excess carriers in them. We demonstrate the possibility of determination of the hole recombination lifetime in GeSi nanoislands from the temperature and field dependences of the photosensitivity.

  11. A polychromator-type near-infrared spectrometer with a high-sensitivity and high-resolution photodiode array detector for pharmaceutical process monitoring on the millisecond time scale

    NASA Astrophysics Data System (ADS)

    Murayama, Kodai; Genkawa, Takuma; Ishikawa, Daitaro; Komiyama, Makoto; Ozaki, Yukihiro

    2013-02-01

    In the fine chemicals industry, particularly in the pharmaceutical industry, advanced sensing technologies have recently begun being incorporated into the process line in order to improve safety and quality in accordance with process analytical technology. For estimating the quality of powders without preparation during drug formulation, near-infrared (NIR) spectroscopy has been considered the most promising sensing approach. In this study, we have developed a compact polychromator-type NIR spectrometer equipped with a photodiode (PD) array detector. This detector is consisting of 640 InGaAs-PD elements with 20-μm pitch. Some high-specification spectrometers, which use InGaAs-PD with 512 elements, have a wavelength resolution of about 1.56 nm when covering 900-1700 nm range. On the other hand, the newly developed detector, having the PD with one of the world's highest density, enables wavelength resolution of below 1.25 nm. Moreover, thanks to the combination with a highly integrated charge amplifier array circuit, measurement speed of the detector is higher by two orders than that of existing PD array detectors. The developed spectrometer is small (120 mm × 220 mm × 200 mm) and light (6 kg), and it contains various key devices including the high-density and high-sensitivity PD array detector, NIR technology, and spectroscopy technology for a spectroscopic analyzer that has the required detection mechanism and high sensitivity for powder measurement, as well as a high-speed measuring function for blenders. Moreover, we have evaluated the characteristics of the developed NIR spectrometer, and the measurement of powder samples confirmed that it has high functionality.

  12. An Ultra-Performance Liquid Chromatography Photodiode Array Detection Tandem Mass Spectrometric Method for Simultaneous Determination of Seven Major Bioactive Constituents in Xiaochaihutang and Its Application to Fourteen Compatibilities Study.

    PubMed

    Wang, Lijuan; Wu, Chunfu; Zhao, Longshan; Lu, Xiumei; Wang, Fang; Yang, Jingyu; Xiong, Zhili

    2015-10-01

    A rapid and sensitive ultra-performance liquid chromatography photodiode array detection tandem mass spectrometric method (UPLC-PDA-MS-MS) was developed and validated to simultaneously determine seven major bioactive constituents in the formula of traditional Chinese medicines Xiaochaihutang (XCHT). To investigate the discipline of compatibility in XCHT, 14 kinds of compatibilities designed by orthogonal array were also analyzed. The separation was performed on an ACQUITY UPLC™ BEH C18 column (100 × 2.1 mm, 1.7 µm) using gradient elution with a mobile phase of 0.1% formic acid and acetonitrile at a flow rate of 0.2 mL/min. Two detection techniques of PDA detector and MS-MS detector were proposed, respectively. The concentrations of baicalin and wogonoside were high enough for PDA detection while low-concentration bioactive constituents including saikosaponin a, ginsenoside Rg1, liquiritin, baicalein and wogonin were quantified by MS-MS detection. The proposed method was fully validated in terms of sensitivity, linearity, specificity, precision, repeatability and recovery. This is the first report on the simultaneous determination of the major bioactive constituents of XCHT by UPLC-PDA-MS-MS, which could be used to evaluate the quality of XCHT and to investigate the discipline of compatibility in XCHT. PMID:26024854

  13. Design of a silicon avalanche photodiode pixel with integrated laser diode using back-illuminated crystallographically etched silicon-on-sapphire with monolithically integrated microlens for dual-mode passive and active imaging arrays

    NASA Astrophysics Data System (ADS)

    Stern, Alvin G.

    2010-08-01

    There is a growing need in scientific research applications for dual-mode, passive and active 2D and 3D LADAR imaging methods. To fill this need, an advanced back-illuminated silicon avalanche photodiode (APD) design is presented using a novel silicon-on-sapphire substrate incorporating a crystalline aluminum nitride (AlN) antireflective layer between the silicon and R-plane sapphire. This allows integration of a high quantum efficiency silicon APD with a gallium nitride (GaN) laser diode in each pixel. The pixel design enables 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 TMAH solution, 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, φ c = 54.7°. The APD device is fabricated in the mesa using conventional silicon processing technology. The GaN laser diode is fabricated by epitaxial growth inside of an inverted, etched cavity in the silicon mesa. Microlenses are fabricated in the thinned, and AR-coated sapphire substrate. The APDs share a common, front-side anode contact, and laser diodes share a common cathode. A low resistance (Al) or (Cu) metal anode grid fills the space between pixels and also inhibits optical crosstalk. SOS-APD arrays are flip-chip bump-bonded to CMOS readout ICs to produce hybrid FPAs. The square 27 μm emitter-detector pixel achieves SNR > 1 in active detection mode for Lambert surfaces at 1,000 meters.

  14. 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.

  15. Rapid characterisation and comparison of saponin profiles in the seeds of Korean Leguminous species using ultra performance liquid chromatography with photodiode array detector and electrospray ionisation/mass spectrometry (UPLC-PDA-ESI/MS) analysis.

    PubMed

    Ha, Tae Joung; Lee, Byong Won; Park, Ki Hun; Jeong, Seong Hun; Kim, Hyun-Tae; Ko, Jong-Min; Baek, In-Youl; Lee, Jin Hwan

    2014-03-01

    The present work was reported on investigation of saponin profiles in nine different legume seeds, including soybean, adzuki bean, cowpea, common bean, scarlet runner bean, lentil, chick pea, hyacinth bean, and broad bean using ultra performance liquid chromatography with photodiode array detector and electrospray ionisation/mass spectrometry (UPLC-PDA-ESI/MS) technique. A total of twenty saponins were characterised under rapid and simple conditions within 15min by the 80% methanol extracts of all species. Their chemical structures were elucidated as soyasaponin Ab (1), soyasaponin Ba (2), soyasaponin Bb (3), soyasaponin Bc (4), soyasaponin Bd (5), soyasaponin αg (6), soyasaponin βg (7), soyasaponin βa (8), soyasaponin γg (9), soyasaponin γa (10), azukisaponin VI (11), azukisaponin IV (12), azukisaponin II (13), AzII (14), AzIV (15), lablaboside E (16), lablaboside F (17), lablaboside D (18), chikusetusaponin IVa (19), and lablab saponin I (20). The individual and total saponin compositions exhibited remarkable differences in all legume seeds. In particular, soyasaponin βa (8) was detected the predominant composition in soybean, cowpea, and lentil with various concentrations. Interestingly, soybean, adzuki bean, common bean, and scarlet runner bean had high saponin contents, while chick pea and broad bean showed low contents. PMID:24176342

  16. Quantitative Determination of Spermidine in 50 German Cheese Samples on a Core-Shell Column by High-Performance Liquid Chromatography with a Photodiode Array Detector Using a Fully Validated Method.

    PubMed

    Esatbeyoglu, Tuba; Ehmer, Andreas; Chaize, Delphine; Rimbach, Gerald

    2016-03-16

    In the current study, the spermidine (8) contents of 51 German and 9 international cheese samples (from France, Ireland, Italy, The Netherlands, and Switzerland) were analyzed by a modified and fully validated method using high-performance liquid chromatography with photodiode array detection. After precolumn derivatization of biogenic amines with dansyl chloride (11), the compounds were separated on a Kinetex C18 column and detected at λ = 254 nm. This method for compound 8 analysis in cheese was validated for the first time according to U.S. Food and Drug Administration (FDA) guidelines for bioanalytical method validation with regard to selectivity, precision, accuracy, recovery, linearity, lower limit of detection (LOD), lower limit of quantitation (LOQ), standard solution stability, short- and long-term stability, freeze-thaw stability, and benchtop stability. The detector response was linear from 0.002 to 8 mg/L 8 (R(2) > 0.999). Low LOD and LOQ values of 1 and 2 μg/L, respectively, reflected the high sensitivity of the method. The intra- and interday recoveries of the 8-spiked cheese samples ranged between 87.7 and 102.6%. This validated method was selective, accurate, and precise and was successfully applied for the quantitative analysis of compound 8 in 60 cheese samples. Furthermore, the simultaneous detection of eight additional biogenic amines is possible but not validated. PMID:26915410

  17. Ultrasound-assisted matrix solid phase dispersive extraction for the simultaneous analysis of β-lactams (four penicillins and eight cephalosporins) in milk by high performance liquid chromatography with photodiode array detection.

    PubMed

    Karageorgou, Eftichia G; Samanidou, Victoria F; Papadoyannis, Ioannis N

    2012-10-01

    The application of ultrasound-assisted matrix solid phase dispersive extraction for the confirmatory analysis of 12 β-lactam antibiotics in milk by high performance liquid chromatography with photodiode array detection has been proposed herein. Four penicillins (cloxacillin, dicloxacillin, oxacillin, and amoxicillin) and eight cephalosporins (cefaclor, cefadroxil, ceftiofur, cefuroxime, cefoperazone, cefazolin, cephalexin, and cefotaxime) are effectively extracted using a mixed sorbent of Quick Easy Cheap Effective Rugged Safe technique and OASIS HLB providing a matrix free from any endogenous interference. Examined analytes were well resolved on an Inertsil ODS-3 analytical column with a mobile phase of CH(3)COONH(4) (0.05 M) and acetonitrile delivered under a gradient program. 1,7-Dimethyl-xanthine was used as internal standard. The method was validated meeting the European Legislation determining linearity, selectivity, stability, decision limit, detection capability, accuracy, precision, and ruggedness according to the Youden approach. Recoveries of all antibiotics rated from 85.0 to 115.7%, while RSD values were <12.7%. Finally, the method was successfully applied to milk samples purchased from local market. PMID:22941669

  18. Automated detection and interpretation of spectral information using cross-correlation, millilitre volumes, pneumatic nebulization sample introduction and inductively coupled plasma-atomic emission spectrometry with photodiode array detection

    NASA Astrophysics Data System (ADS)

    Karanassios, V.; Drouin, P. J.; Spiers, G. A.

    1998-08-01

    A method for automated detection and interpretation of spectral information from ˜230 nm spectral windows, millilitre volume samples for 15 elements is presented. The basic approach involves cross-correlation of a spectral pattern obtained by running laboratory prepared multi-element `unknowns' with a reference spectral pattern obtained by running a single element standard. From the resultant cross-correlogram, it can be decided whether or not the sought-for reference spectral pattern (and the corresponding element) are present in the unknown. Spectral patterns were acquired using an inductively coupled plasma-atomic emission spectrometry (ICP-AES) system equipped with a linear, 1024-element, photo-diode array (Leco, Plasmarray). Reference spectral patterns for Al, Au, Be, Cd, Cu, Ga, Mg, Mn, Ni, Pd, Si, Sc, Y, Sr and Zn were converted to noise-free and interference-free binary software masks and, subsequently, to analogue software masks. Cross-correlation of the analogue masks with spectral patterns acquired by running multi-element unknowns is discussed, an algorithm that does not rely on fast Fourier transforms (FFT) to calculate cross-correlations is presented and a context-sensitive, colour-coded and interrogatable periodic table graphical user-interface that presents the likely composition of an unknown on the computer screen is described in detail.

  19. Robust method for investigating nitrogen metabolism of 15N labeled amino acids using AccQ•Tag ultra performance liquid chromatography-photodiode array-electrospray ionization-mass spectrometry: application to a parasitic plant-plant interaction.

    PubMed

    Gaudin, Zachary; Cerveau, Delphine; Marnet, Nathalie; Bouchereau, Alain; Delavault, Philippe; Simier, Philippe; Pouvreau, Jean-Bernard

    2014-01-21

    An AccQ•Tag ultra performance liquid chromatography-photodiode array-electrospray ionization-mass spectrometry (AccQ•Tag-UPLC-PDA-ESI-MS) method is presented here for the fast, robust, and sensitive quantification of (15)N isotopologue enrichment of amino acids in biological samples, as for example in the special biotic interaction between the cultivated specie Brassica napus (rapeseed) and the parasitic weed Phelipanche ramosa (broomrape). This method was developed and validated using amino acid standard solutions containing (15)N amino acid isotopologues and/or biological unlabeled extracts. Apparatus optimization, limits of detection and quantification, quantification reproducibility, and calculation method of (15)N isotopologue enrichment are presented. Using this method, we could demonstrate that young parasite tubercles assimilate inorganic nitrogen as (15)N-ammonium when supplied directly through batch incubation but not when supplied by translocation from host root phloem, contrary to (15)N2-glutamine. (15)N2-glutamine mobility from host roots to parasite tubercles followed by its low metabolism in tubercles suggests that the host-derived glutamine acts as an important nitrogen containing storage compound in the young tubercle of Phelipanche ramosa. PMID:24359440

  20. ZnO homojunction photodiodes based on Sb-doped p-type nanowire array and n-type film for ultraviolet detection

    SciTech Connect

    Wang Guoping; Chu Sheng; Zhan Ning; Liu Jianlin; Lin Yuqing; Chernyak, Leonid

    2011-01-24

    ZnO p-n homojunctions based on Sb-doped p-type nanowire array and n-type film were grown by combining chemical vapor deposition (for nanowires) with molecular-beam epitaxy (for film). Indium tin oxide and Ti/Au were used as contacts to the ZnO nanowires and film, respectively. Characteristics of field-effect transistors using ZnO nanowires as channels indicate p-type conductivity of the nanowires. Electron beam induced current profiling confirmed the existence of ZnO p-n homojunction. Rectifying I-V characteristic showed a turn-on voltage of around 3 V. Very good response to ultraviolet light illumination was observed from photocurrent measurements.

  1. Simultaneous determination of phenolic acids and flavonoids in rice using solid-phase extraction and RP-HPLC with photodiode array detection.

    PubMed

    Irakli, Maria N; Samanidou, Victoria F; Biliaderis, Costas G; Papadoyannis, Ioannis N

    2012-07-01

    An analytical method based on an optimized solid-phase extraction procedure and followed by high-performance liquid chromatography (HPLC) separation with diode array detection was developed and validated for the simultaneous determination of phenolic acids (gallic, protocatechuic, 4-hydroxy-benzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, sinapic, and cinnamic acids), flavanols (catechin and epicatechin), flavonols (myricetin, quercetin, kaempferol, quercetin-3-O-glucoside, hyperoside, and rutin), flavones (luteolin and apigenin) and flavanones (naringenin and hesperidin) in rice flour (Oryza sativa L.). Chromatographic separation was carried out on a PerfectSil Target ODS-3 (250 mm × 4.6 mm, 3 μm) column at temperature 25°C using a mobile phase, consisting of 0.5% (v/v) acetic acid in water, methanol, and acetonitrile at a flow rate 1 mL min(-1) , under gradient elution conditions. Application of optimum extraction conditions, elaborated on both Lichrolut C(18) and Oasis HLB cartridges, have led to extraction of phenolic acids and flavonoids from rice flour with mean recoveries 84.3-113.0%. The developed method was validated in terms of linearity, accuracy, precision, stability, and sensitivity. Repeatability (n = 5) and inter-day precision (n = 4) revealed relative standard deviation (RSD) <13%. The optimized method was successfully applied to the analysis of phenolic acids and flavonoids in pigmented (red and black rice) and non-pigmented rice (brown rice) samples. PMID:22761138

  2. Comparison of Stability-Indicating LC Methods Using Light Scattering and Photodiode Array Detection with Monolithic Column for Determination of Quinapril and Hydrochlorothiazide.

    PubMed

    de Diego, Marta; Godoy, Ricardo; Mennickent, Sigrid; Vergara, Carola; Charnock, Henry; Hernández, Camilo

    2016-09-01

    Rapid stability-indicating LC methods for simultaneous analysis of quinapril and hydrochlorothiazide were developed, validated and compared using evaporative light scattering detection (ELSD) and diode array detection (DAD). For the separation of quinapril, hydrochlorothiazide and its major degradation products, a monolithic column was used and the analytes were eluted within 7 min, applying gradient mobile phase in both methods. Quinapril was subjected to hydrolytic, oxidative, thermal, humidity and photolytic stress conditions. Degradation products were well resolved from main peaks and from each other, proving the stability-indicating power of the methods. The response with DAD was linear and the response with ELSD was fitted to a power function, for quinapril and hydrochlorothiazide concentrations of 20-160 and 12.5-100 µg mL(-1), respectively. DAD method achieved better precision than ELSD method, the LOQ of DAD was lower and the accuracy of the methods was similar. Quinapril degrade by hydrolysis and thermal stress, showing the formation of quinaprilat and quinapril diketopiperazine as degradants, which were identified by MS-MS. The methods were successfully applied to quantify quinapril and hydrochlorothiazide in commercial tablets. LC-DAD and LC-ELSD methods are suitable to assess the stability and routine analysis of quinapril and hydrochlorothiazide in pharmaceutical industry. PMID:27165572

  3. An improved high performance liquid chromatography-photodiode array detection-atmospheric pressure chemical ionization-mass spectrometry method for determination of chlorophylls and their derivatives in freeze-dried and hot-air-dried Rhinacanthus nasutus (L.) Kurz.

    PubMed

    Kao, Tsai Hua; Chen, Chia Ju; Chen, Bing Huei

    2011-10-30

    Rhinacanthus nasutus (L.) Kurz, a traditional Chinese herb possessing antioxidant and anti-cancer activities, has been reported to contain functional components like carotenoids and chlorophylls. However, the variety and amount of chlorophylls remain uncertain. The objectives of this study were to develop a high performance liquid chromatography-photodiode array detection-atmospheric pressure chemical ionization-mass spectrometry (HPLC-DAD-APCI-MS) method for determination of chlorophylls and their derivatives in hot-air-dried and freeze-dried R. nasutus. An Agilent Eclipse XDB-C18 column and a gradient mobile phase composed of methanol/N,N-dimethylformamide (97:3, v/v), acetonitrile and acetone were employed to separate internal standard zinc-phthalocyanine plus 12 cholorophylls and their derivatives within 21 min, including chlorophyll a, chlorophyll a', hydroxychlorophyll a, 15-OH-lactone chlorophyll a, chlorophyll b, chlorophyll b', hydroxychlorophyll b, pheophytin a, pheophytin a', hydroxypheophytin a, hydroxypheophytin a' and pheophytin b in hot-air-dried R. nasutus with flow rate at 1 mL/min and detection at 660 nm. But, in freeze-dried R. nasutus, only 4 chlorophylls and their derivatives, including chlorophyll a, chlorophyll a', chlorophyll b and pheophytin a were detected. Zinc-phthalocyanine was found to be an appropriate internal standard to quantify all the chlorophyll compounds. After quantification by HPLC-DAD, both chlorophyll a and pheophytin a were the most abundant in hot-air-dried R. nasutus, while in freeze-dried R. nasutus, chlorophyll a and chlorophyll b dominated. PMID:22063550

  4. Simultaneous determination of three diarylheptanoids and an alpha-tetralone derivative in the green walnut husks (Juglans regia L.) by high-performance liquid chromatography with photodiode array detector.

    PubMed

    Liu, Junxi; Meng, Min; Li, Chen; Huang, Xinyi; Di, Duolong

    2008-05-01

    By optimizing extraction, separation and analytical conditions, a reliable and accurate high-performance liquid chromatographic (HPLC) method coupled with photodiode array detector (DAD) at room temperature is developed for simultaneous determination of three diarylheptanoids (juglanin A, juglanin B, rhoiptelol) and an alpha-tetralone derivative (regiolone) in methanol extracts from the green walnut husks (Juglans regia L.) The sample pretreatment process involved the reflux extraction using methanol as the extract with a ratio of liquor to sample of 15 mL/g. The separation was achieved on a SinoChrom ODS-AP C(18) column with gradient elution using acetonitrile and 2% (v/v) acetic acid in water. The intra-day and inter-day precision (RSD%) for the analytes ranged from 1.08 to 1.51 and 0.60 to 1.13, respectively. The average recoveries obtained were from 88.4% to 96.2% for the analytes with RSDs below 3.13%. The correlation coefficients of the calibration curve exceeded 0.999. The detection limits were 0.51, 0.25, 0.32 and 0.35 ng at a signal-to-noise ratio of 3, respectively. Quantitative analyses of the samples from different grown sites and in obtained different months showed that the contents of the analytes varied significantly. The method was then successfully applied for the detection and isolation of a new diarylheptanoid derivative in the green walnut husks (J. regia L.). The structure of the new compound was elucidated by various spectroscopic methods including 2D NMR techniques (COSY, HMQC, HMBC), HR-ESI-MS and X-ray single-crystal diffraction analysis. PMID:18343385

  5. Validation of an immunoassay method for the determination of traces of carbaryl in vegetable and fruit extracts by liquid chromatography with photodiode array and mass spectrometric detection.

    PubMed

    Nunes, G S; Marco, M P; Ribeiro, M L; Barceló, D

    1998-10-01

    A competitive enzyme-linked immunosorbent assay (ELISA) method for carbaryl quantitation in crop extracts was validated by liquid chromatography (LC) with diode array detection (DAD). For this purpose, six crops (banana, carrot, green bean, orange, peach and potato) were chosen for recovery and reproducibility studies. The general sample preparation included extraction with methanol followed by liquid-liquid partitioning and clean-up on Celite-charcoal adsorbent column of the vegetable extracts. ELISA samples consisted of a diluted LC extract in assay phosphate buffer (pH 7.5). The potential effect of methanol in these samples was evaluated. It was observed that a maximum content of 10% methanol present in the assay buffer could be tolerated without expressive losses in the ELISA performance. Under these conditions, a IC50 approximately 1.48 micrograms l-1 was obtained. A minimum matrix effect with a 1:50 dilution of the methanolic extracts in assay buffer was noticed, except for green bean samples that inhibited completely the assay. For the vegetable extracts, the ELISA sensitivities varied from 3.9 to 5.7 micrograms l-1, and good recoveries (82-96%) with R.S.D.s ranging from 5.7 to 12.1% were found. An excellent correlation between the LC-DAD and ELISA techniques was obtained. The confirmation of the carbaryl in less concentrated samples was achieved by LC-mass spectrometry interfaced with atmospheric pressure chemical ionisation. The [M + H]+ = 202 and [M + H-57]+ = 145 ions, equivalent to the protonated molecular and 1-naphthol ions, respectively, were used to carbaryl identification in these samples. PMID:9818398

  6. Determination of selected water-soluble vitamins using hydrophilic chromatography: a comparison of photodiode array, fluorescence, and coulometric detection, and validation in a breakfast cereal matrix.

    PubMed

    Langer, Swen; Lodge, John K

    2014-06-01

    Water-soluble vitamins are an important class of compounds that require quantification from food sources to monitor nutritional value. In this study we have analysed six water-soluble B vitamins ([thiamine (B1), riboflavin (B2), nicotinic acid (B3, NAc), nicotinamide (B3, NAm), pyridoxal (B6), folic acid (B9)], and ascorbic acid (vit C) with hydrophilic interaction liquid chromatography (HILIC), and compared UV, fluorescent (FLD) and coulometric detection to optimise a method to quantitate the vitamins from food sources. Employing UV/diode array (DAD) and fluorimetric detection, six B vitamins were detected in a single run using gradient elution from 100% to 60% solvent B [10mM ammonium acetate, pH 5.0, in acetonitrile and water 95:5 (v:v)] over 18 min. UV detection was performed at 268 nm for B1, 260 nm for both B3 species and 284 nm for B9. FLD was employed for B2 at excitation wavelength of 268 nm, emission of 513 nm, and 284 nm/317 nm for B6. Coulometric detection can be used to detect B6 and B9, and vit C, and was performed isocratically at 75% and 85% of solvent B, respectively. B6 was analysed at a potential of 720 mV, while B9 was analysed at 600 mV, and vit C at 30 mV. Retention times (0.96 to 11.81 min), intra-day repeatability (CV 1.6 to 3.6), inter-day variability (CV 1.8 to 11.1), and linearity (R 0.9877 to 0.9995) remained good under these conditions with limits of detection varying from 6.6 to 164.6 ng mL(-1), limits of quantification between 16.8 and 548.7 ng mL(-1). The method was successfully applied for quantification of six B vitamins from a fortified food product and is, to our knowledge, the first to simultaneously determine multiple water-soluble vitamins extracted from a food matrix using HILIC. PMID:24792530

  7. Reversed-phase high-performance Liquid Chromatography-ultraviolet Photodiode Array Detector Validated Simultaneous Quantification of six Bioactive Phenolic Acids in Roscoea purpurea Tubers and their In vitro Cytotoxic Potential against Various Cell Lines

    PubMed Central

    Srivastava, Sharad; Misra, Ankita; Kumar, Dharmesh; Srivastava, Amit; Sood, Anil; Rawat, AKS

    2015-01-01

    Background: Roscoea purpurea or Roscoea procera Wall. (Zingiberaceae) is traditionally used for nutrition and in the treatment of various ailments. Objective: Simultaneous reversed-phase high-performance liquid chromatography-ultraviolet (RP-HPLC) photodiode array detector identification of phenolic acids (PA's) was carried out in whole extract of tuber and their cytotoxic potential was estimated along with radical scavenging action. Bioactivity guided fractionation was also done to check the response potential against the same assay. Materials and Methods: Identification and method validation was performed on RP-HPLC column and in vitro assays were used for bioactivity. Results: Protocatechuic acid, syringic acid, ferulic acid, rutin, apigenin, and kaempferol were quantified as 0.774%, 0.064%, 0.265%, 1.125%, 0.128%, and 0.528%, respectively. Validated method for simultaneous determination of PA's was found to be accurate, reproducible, and linearity was observed between peak area response and concentration. Recovery of identified PA's was within the acceptable limit of 97.40–104.05%. Significant pharmacological response was observed in whole extract against in vitro cytotoxic assay, that is, Sulforhodamine B assay, however, fractionation results in decreased action potential. Similar pattern of results were observed in the antioxidant assay, as total phenolic content and total flavonoid content were highest in whole extract and decreases with fractionation. Radical scavenging activity was prominent in chloroform fraction, exhibiting IC50 at 0.25 mg/mL. Conclusion: Study, thus, reveals that R. purpurea exhibit significant efficacy in cytotoxic activity with the potentiality of scavenging free radicals due the presence of PA's as reported through RP-HPLC. SUMMARY Proto-catechuic acid, syringic acid, ferulic acid, rutin, apigenin and kaempferol were quantified as 0.774, 0.064, 0.265, 1.125, 0.128 and 0.528 %Preliminary cytotoxic activity revealed that whole

  8. Breadboard linear array scan imager program

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The performance was evaluated of large scale integration photodiode arrays in a linear array scan imaging system breadboard for application to multispectral remote sensing of the earth's resources. Objectives, approach, implementation, and test results of the program are presented.

  9. 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.

  10. 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.

  11. PtSi Schottky-barrier focal plane arrays for multispectral imaging in ultraviolet, visible, and infrared spectral bands

    NASA Astrophysics Data System (ADS)

    Tsaur, Bor-Yeu; Chen, C. K.; Mattia, John-Paul

    1990-04-01

    PtSi Schottky-barrier detectors, which are conventionally used in the back-illumination mode for thermal imaging in the 3-5 micron infrared (IR) spectral band, are shown to exhibit excellent photoresponse in the near-ultraviolet and visible regions when operated in the front-illumination mode. For devices without antireflection coatings, external quantum efficiency in excess of 60 percent has been obtained for wavelengths between 400 and 800 nm. The efficiency decreases below 400 nm but is still about 35 percent at 290 nm. High-quality imaging has been demonstrated in both the visible and 3-5 micron spectral bands for front-illuminated 160- x 244-element PtSi focal plane arrays integrated with monolithic CCD readout circuitry.

  12. Effect of different drying methods on the quality of Angelicae Sinensis Radix evaluated through simultaneously determining four types of major bioactive components by high performance liquid chromatography photodiode array detector and ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    Bai, Ying-Jia; Kong, Ming; Xu, Jin-Di; Zhang, Xiao-Lin; Zhou, Shan-Shan; Wang, Xiao-Ning; Liu, Li-Fang; Li, Song-Lin

    2014-06-01

    In the present study, the effect of drying methods on the quality of Angelicae Sinensis Radix (DG), was evaluated by newly developed high performance liquid chromatography photodiode array detector (HPLC-DAD) and ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS/MS). Ten major bioactive components including two phenolic acids, two hydroxyl phthalides, four alkyl phthalides and two phthalide dimers were selected as evaluation chemical markers and the newly-established method was qualitatively and quantitatively validated. DG slices and whole roots dried in shade, sun light, hot air, vacuum, microwave, far infrared ray and combination of microwave and far infrared ray as well as the fresh DG samples were determined by the established methods. DG slices dried in hot air kept the similar chemical composition to that of fresh DG, while DG whole roots dried in vacuum retained highest contents of the major components. Coniferyl ferulate and ligustilide degraded significantly in DG slices dried by microwave, far infrared ray and their combination. The influence of such chemical changes induced by different drying methods on the bioactivities of DG warrants further investigation, so that the optimal drying method can be obtained for the standardization of DG herb. PMID:24561333

  13. Three-dimensional numerical simulation of planar P+n heterojunction In0.53Ga0.47As photodiodes in dense arrays part II: modulation transfer function modeling

    NASA Astrophysics Data System (ADS)

    Wichman, Adam R.; DeWames, Roger E.; Bellotti, Enrico

    2014-06-01

    Processing improvements have facilitated manufacturing reduced pixel dimensions for lattice-matched InGaAs on InP short-wave infrared detectors. Due to its technological maturity, this material system continues to garner attention for low-light level imaging applications. With pixel dimensions smaller than minority carrier diffusion lengths, optimizing array performance by reducing crosstalk from lateral carrier diffusion remains an important design issue. Analytical models, however, have provided limited insight on underlying mechanisms limiting device performance in the conventional planar double heterointerface device. Quantitative modeling provides tools to investigate performance sensitivities and their underlying mechanisms. In this work we develop a three-dimensional numerical simulation for dense P+n In0.53Ga0.47As on InP photo detector focal plane arrays using a conventional planar, back-illuminated structure. We evaluate optical generation with finite-difference time-domain analysis, and model carrier transport in a drift diffusion analysis simultaneously solving the carrier continuity and Poisson equations. Using this model we investigate modulation transfer function variations with pixel pitch and diffused junction geometries for small dimension arrays. By accounting for carrier diffusion effects, these results should provide a benchmark against which to evaluate modulation transfer function contributions from other effects, such as crosstalk attributable to photon recycling.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. High-performance liquid chromatography with photodiode array detection (HPLC-DAD)/HPLC-mass spectrometry (MS) profiling of anthocyanins from Andean Mashua Tubers (Tropaeolum tuberosum Ruíz and Pavón) and their contribution to the overall antioxidant activity.

    PubMed

    Chirinos, Rosana; Campos, David; Betalleluz, Indira; Giusti, M Monica; Schwartz, Steven J; Tian, Qingguo; Pedreschi, Romina; Larondelle, Yvan

    2006-09-20

    Mashua (Tropaeolum tuberosum Ruíz and Pavón), an Andean tuber with high antioxidant activity, has sparked interest because of its traditional medicinal use. In this study, we evaluated the anthocyanin composition for three purple mashua genotypes and their contribution to the overall antioxidant activity of the tuber. Mashua anthocyanins, total phenolics, and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) antioxidant activity ranged from 45.5 to 131.9 mg of cyanidin 3-glucoside equivalents/100 g fresh weight (FW), 174.9 to 275.5 mg of gallic acid equivalents/100 g of FW, and 16.2 to 45.7 micromol of Trolox equivalents/g of FW, respectively. The high-performance liquid chromatography with photodiode array detection (HPLC-DAD) and HPLC-electrospray ionization tandem mass spectrometry (ESI/MS-MS) profiles revealed the presence of 11 different anthocyanins. The two major pigments (56.4-73.0% total area range at 520 nm) were identified as delphinidin 3-glucoside-5-acetylrhamnoside and delphinidin 3-sophoroside-5-acetylrhamnoside. Other pigments were delphinidin 3-glucoside-5-rhamnoside, delphinidin 3-sophoroside-5-rhamnoside, delphinidin 3-glucoside, cyanidin 3-sophoroside, and cyanidin 3-sophoroside-5-rhamnoside. Cyanidin 3-glucoside and cyanidin 3-rutinoside were only found in two genotypes, while pelargonidin 3-sophoroside and pelargonidin 3-sophoroside-5-rhamnoside were only found in the third one. Anthocyanins from mashua were the major contributors to the total ABTS values for only one of the three genotypes, suggesting that other phenolics present are playing a major role in the antioxidant power of mashua tubers. Results from this study provide important information for the Nutraceutical and Functional Food Market for the use of mashua anthocyanins not only as a source of natural colorants but also as a source of phytonutrients. PMID:16968067

  2. 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.

  3. 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.

  4. Solid state image sensing arrays

    NASA Technical Reports Server (NTRS)

    Sadasiv, G.

    1972-01-01

    The fabrication of a photodiode transistor image sensor array in silicon, and tests on individual elements of the array are described along with design for a scanning system for an image sensor array. The spectral response of p-n junctions was used as a technique for studying the optical-absorption edge in silicon. Heterojunction structures of Sb2S3- Si were fabricated and a system for measuring C-V curves on MOS structures was built.

  5. 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.

  6. 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.

  7. 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.

  8. 2048 pixel front illuminated linear CCD for spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Chao-min; Liu, Chang-ju; Zheng, Yu; Li, Ping

    2009-07-01

    The charge couple device(CCD) used in spectroscopy requests good response to the wave bands between 190-1000 nm. The common measure to carry out UV response is phosphor coatings or back illuminated. Among them, phosphors are wavelength converters that convert short-wavelength light into the visible spectral region. This technology needs adding special process which not only raises cost, reduces yield, but also reduces the resolution of the image. Back illuminated is reducing CCD thickness to 15um which is thinner than the normal paper by mechanical polishing and chemical corrosion after completing the front processes of CCD. This technology needs special instrument, complex process , and the yield is also low. Both phosphor coatings and back illuminated have some disadvantages such as low space resolution, complex process, low yield, high cost etc. The CCD of traditional structure has no response to the wavelength less than 350nm, the reason is that the length of UV penetrating through Si is shallow, the penetrating length is only 6.5nm of 300nm UV, the shorter wavelength UV, the shallower penetrating length. The junction depth of normal CCD process is above 200nm, some realize shallow junction through molecular beam epitaxy, but the instrument is expensive and the cost is high. The photosensitive area of normal structure CCD adopting portrait P-N junction, light incidences from N area, N area can't be completely depleted because of the restrict of physics, photon can't arrive depletion area directly. On the basis of thorough analysis traditional UV CCD, horizontal P-N junction structure of Photosensitive area is put forward, whose depletion can reach the surface, the photon falls depletion area directly, which can effectively carry out the absorption of the UV light and the collection of photoelectron. As the latent absorption of Si3N4 to UV with less than 248nm wavelength, the Si3N4 passivation on the photosensitive area is take out. The improved 2048 elements linear CCD achieves excellent wide spectral response, the maximum quantum efficiency comes to 65% in the ultraviolet band and the average quantum efficiency comes to 40% between 190nm and 1000nm wave band.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  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. 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.

  20. 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

  1. 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.

  2. 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.

  3. Self-guarding Schottky barrier infrared detector array

    NASA Astrophysics Data System (ADS)

    Shepherd, F. D., Jr.; Pellegrini, P. W.; Ludington, C. E.; Weeks, M. M.

    1985-07-01

    A two dimensional focal plane array of Schottky photodiodes on a silicon substrate for infrared imaging is presented. The array is designed for mating with multiplexing circuitry and has a self-guarding feature wherein adjacent Schottky electrodes act as guard electrodes. This feature allows a substantial increase of the focal plane area coverage ratio.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. Photosensitive biosensor array system using optical addressing without an addressing circuit on array biochips

    NASA Astrophysics Data System (ADS)

    Ahn, Chang-Geun; Ah, Chil Seong; Kim, Tae-Youb; Park, Chan Woo; Yang, Jong-Heon; Kim, Ansoon; Sung, Gun Yong

    2010-09-01

    This paper introduces a photosensitive biosensor array system with a simple photodiode array that detects photocurrent changes caused by reactions between probe and target molecules. Using optical addressing, the addressing circuit on the array chip is removed for low-cost application, and real cell addressing is achieved using an externally located computer-controllable light-emitting diode array module. The fabricated biosensor array chip shows a good dynamic range of 1-100 ng/mL under prostate-specific antigen detection, with an on-chip resolution of roughly 1 ng/mL.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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).

  9. 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 %.

  10. 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.

  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. 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).

  13. Synthetic Array Heterodyne Detection: Developments within the Caliope CO{sub 2} DIAL Program

    SciTech Connect

    Rehse, S.J.; Strauss, E.M.

    1995-09-01

    A new technique, Synthetic Array Heterodyne Detection, offers a wider field of view and improved signal to noise for coherent DIAL systems by reducing speckle interference. We have implemented a synthetic multi-pixel array using a CO{sub 2} laser on a single element HgCdTe photodiode.

  14. Future sensor system needs for staring arrays

    NASA Astrophysics Data System (ADS)

    Miller, John Lester

    2011-05-01

    This is a systems application paper regarding how sensor systems may use future technology FPAs. A historical perspective is discussed along with lessons learned from previous technologies. Future system requirements for strained super-lattice (SLS), quantum dots (QDOT) and traditional quantum well infrared photo-diodes (QWIP) arrays will be presented from both a commercial and military perspective. New potential markets will open up in the future if certain FPA technologies can reduce cost and provide higher sensitivities at higher operating temperatures.

  15. Analysis and modeling of optical crosstalk in InP-based Geiger-mode avalanche photodiode FPAs

    NASA Astrophysics Data System (ADS)

    Chau, Quan; Jiang, Xudong; Itzler, Mark A.; Entwistle, Mark; Piccione, Brian; Owens, Mark; Slomkowski, Krystyna

    2015-05-01

    Optical crosstalk is a major factor limiting the performance of Geiger-mode avalanche photodiode (GmAPD) focal plane arrays (FPAs). This is especially true for arrays with increased pixel density and broader spectral operation. We have performed extensive experimental and theoretical investigations on the crosstalk effects in InP-based GmAPD FPAs for both 1.06-μm and 1.55-μm applications. Mechanisms responsible for intrinsic dark counts are Poisson processes, and their inter-arrival time distribution is an exponential function. In FPAs, intrinsic dark counts and cross talk events coexist, and the inter-arrival time distribution deviates from purely exponential behavior. From both experimental data and computer simulations, we show the dependence of this deviation on the crosstalk probability. The spatial characteristics of crosstalk are also demonstrated. From the temporal and spatial distribution of crosstalk, an efficient algorithm to identify and quantify crosstalk is introduced.

  16. 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.

  17. 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

  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. 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.

  1. 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.

  2. 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.

  3. 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).

  4. 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.

  5. Infrared to visible image up-conversion using optically addressed spatial light modulator utilizing liquid crystal and InGaAs photodiodes

    NASA Astrophysics Data System (ADS)

    Solodar, A.; Arun Kumar, T.; Sarusi, G.; Abdulhalim, I.

    2016-01-01

    Combination of InGaAs/InP heterojunction photodetector with nematic liquid crystal (LC) as the electro-optic modulating material for optically addressed spatial light modulator for short wavelength infra-red (SWIR) to visible light image conversion was designed, fabricated, and tested. The photodetector layer is composed of 640 × 512 photodiodes array based on heterojunction InP/InGaAs having 15 μm pitch on InP substrate and with backside illumination architecture. The photodiodes exhibit extremely low, dark current at room temperature, with optimum photo-response in the SWIR region. The photocurrent generated in the heterojunction, due to the SWIR photons absorption, is drifted to the surface of the InP, thus modulating the electric field distribution which modifies the orientation of the LC molecules. This device can be attractive for SWIR to visible image upconversion, such as for uncooled night vision goggles under low ambient light conditions.

  6. 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.

  7. 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%.

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. Analysis and Enhancement of Low-Light-Level Performance of Photodiode-Type CMOS Active Pixel Images Operated with Sub-Threshold Reset

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata; Yang, Guang; Ortiz, Monico; Wrigley, Christopher; Hancock, Bruce; Cunningham, Thomas

    2000-01-01

    Noise in photodiode-type CMOS active pixel sensors (APS) is primarily due to the reset (kTC) noise at the sense node, since it is difficult to implement in-pixel correlated double sampling for a 2-D array. Signal integrated on the photodiode sense node (SENSE) is calculated by measuring difference between the voltage on the column bus (COL) - before and after the reset (RST) is pulsed. Lower than kTC noise can be achieved with photodiode-type pixels by employing "softreset" technique. Soft-reset refers to resetting with both drain and gate of the n-channel reset transistor kept at the same potential, causing the sense node to be reset using sub-threshold MOSFET current. However, lowering of noise is achieved only at the expense higher image lag and low-light-level non-linearity. In this paper, we present an analysis to explain the noise behavior, show evidence of degraded performance under low-light levels, and describe new pixels that eliminate non-linearity and lag without compromising noise.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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

  12. 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

  13. Post-processing Free Quantum Random Number Generator Based on Avalanche Photodiode Array

    NASA Astrophysics Data System (ADS)

    Yang, Li; Sheng-Kai, Liao; Fu-Tian, Liang; Qi, Shen; Hao, Liang; Cheng-Zhi, Peng

    2016-03-01

    Not Available Supported by the Chinese Academy of Sciences Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, Shanghai Branch, University of Science and Technology of China, and the National Natural Science Foundation of China under Grant No 11405172.

  14. Maximum detection range limitation of pulse laser radar with Geiger-mode avalanche photodiode array

    NASA Astrophysics Data System (ADS)

    Luo, Hanjun; Xu, Benlian; Xu, Huigang; Chen, Jingbo; Fu, Yadan

    2015-05-01

    When designing and evaluating the performance of laser radar system, maximum detection range achievable is an essential parameter. The purpose of this paper is to propose a theoretical model of maximum detection range for simulating the Geiger-mode laser radar's ranging performance. Based on the laser radar equation and the requirement of the minimum acceptable detection probability, and assuming the primary electrons triggered by the echo photons obey Poisson statistics, the maximum range theoretical model is established. By using the system design parameters, the influence of five main factors, namely emitted pulse energy, noise, echo position, atmospheric attenuation coefficient, and target reflectivity on the maximum detection range are investigated. The results show that stronger emitted pulse energy, lower noise level, more front echo position in the range gate, higher atmospheric attenuation coefficient, and higher target reflectivity can result in greater maximum detection range. It is also shown that it's important to select the minimum acceptable detection probability, which is equivalent to the system signal-to-noise ratio for producing greater maximum detection range and lower false-alarm probability.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  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. 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.

  8. Patterning of visible/infrared dual-band microstrip filter arrays for multispectral imaging application

    NASA Astrophysics Data System (ADS)

    Lai, Jian-Jun; Liang, Hua-Feng; Zhou, Zhi-Ping; Fang, Guo-Jia; Li, Li

    2009-08-01

    Visible/infrared dual-band microstrip filter arrays have been developed to be integrated with 512 × 512 PtSi CCD imaging sensor chips for multispectral imaging when it operates in the front-illumination mode. A high visible transmittance and high infrared reflectance ZAO (ZnO:Al) based coating for visible passband and an interference absorbing filter film for a mid-infrared passband have been designed and deposited on sapphire substrates. An effective double-layer lift-off technique that is compatible with high temperature deposition has been developed to create thick microstrip infrared film. The infrared passband film using germanium and yttrium fluoride as high and low refractive indices materials have been deposited by ion-beam-assisted electron beam evaporation. Tested optical performance results reveal that the visible and near-infrared transmittance of the infrared passband film is very low, which makes it ideal for mid-infrared imaging. Environmental durability testing shows that the microstrip arrays have good mechanical and thermal performances for practical applications.

  9. Magnetic arrays

    DOEpatents

    Trumper, D.L.; Kim, W.; Williams, M.E.

    1997-05-20

    Electromagnet arrays are disclosed which can provide selected field patterns in either two or three dimensions, and in particular, which can provide single-sided field patterns in two or three dimensions. These features are achieved by providing arrays which have current densities that vary in the windings both parallel to the array and in the direction of array thickness. 12 figs.

  10. Magnetic arrays

    SciTech Connect

    Trumper, David L.; Kim, Won-jong; Williams, Mark E.

    1997-05-20

    Electromagnet arrays which can provide selected field patterns in either two or three dimensions, and in particular, which can provide single-sided field patterns in two or three dimensions. These features are achieved by providing arrays which have current densities that vary in the windings both parallel to the array and in the direction of array thickness.

  11. Two-dimensional beam-profile monitor using the Reticon MC510A array camera

    SciTech Connect

    Gottschalk, B.

    1981-08-01

    A quantitative two-dimensional beam profile may be obtained from a scintillator viewed by a Reticon camera which uses a 32 x 32 array of photodiodes as its sensing element. In this note, CAMAC-oriented data acquisition electronics which allow one either to transmit the profile to a computer, or to use the monitor in a stand-alone mode are described.

  12. Development of high performance SWIR InGaAs focal plane array

    NASA Astrophysics Data System (ADS)

    Nagi, Richie; Bregman, Jeremy; Mizuno, Genki; Oduor, Patrick; Olah, Robert; Dutta, Achyut K.; Dhar, Nibir K.

    2015-05-01

    Banpil Photonics has developed a novel InGaAs based photodetector array for Short-Wave Infrared (SWIR) imaging, for the most demanding security, defense, and machine vision applications. These applications require low noise from both the detector and the readout integrated circuit arrays. In order to achieve high sensitivity, it is crucial to minimize the dark current generated by the photodiode array. This enables the sensor to function in extremely low light situations, which enables it to successfully exploit the benefits of the SWIR band. In addition to minimal dark current generation, it is essential to develop photodiode arrays with higher operating temperatures. This is critical for reducing the power consumption of the device, as less energy is spent in cooling down the focal plane array (in order to reduce the dark current). We at Banpil Photonics are designing, simulating, fabricating and testing SWIR InGaAs arrays, and have achieved low dark current density at room temperature. This paper describes Banpil's development of the photodetector array. We also highlight the fabrication technique used to reduce the amount of dark current generated by the photodiode array, in particular the surface leakage current. This technique involves the deposition of strongly negatively doped semiconductor material in the area between the pixels. This process reduces the number of dangling bonds present on the edges of each pixel, which prevents electrons from being swept across the surface of the pixels. This in turn drastically reduces the amount of surface leakage current at each pixel, which is a major contributor towards the total dark current. We present the optical and electrical characterization data, as well as the analysis that illustrates the dark current mechanisms. Also highlighted are the challenges and potential opportunities for further reduction of dark current, while maintaining other parameters of the photodiode array, such as size, weight, temperature

  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. Photo sensor array technology development

    NASA Technical Reports Server (NTRS)

    Rossman, M. W.; Young, V. F.; Beall, J. R.

    1977-01-01

    The development of an improved capability photo sensor array imager for use in a Viking '75 type facsimile camera is presented. This imager consists of silicon photodiodes and lead sulfide detectors to cover a spectral range from 0.4 to 2.7 microns. An optical design specifying filter configurations and convergence angles is described. Three electronics design approaches: AC-chopped light, DC-dual detector, and DC-single detector, are investigated. Experimental and calculated results are compared whenever possible using breadboard testing and tolerance analysis techniques. Results show that any design used must be forgiving of the relative instability of lead sulfide detectors. A final design using lead sulfide detectors and associated electronics is implemented by fabrication of a hybrid prototype device. Test results of this device show a good agreement with calculated values.

  15. 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.

  16. Kokkos Array

    Energy Science and Technology Software Center (ESTSC)

    2012-09-12

    The Kokkos Array library implements shared-memory array data structures and parallel task dispatch interfaces for data-parallel computational kernels that are performance-portable to multicore-CPU and manycore-accelerator (e.g., GPGPU) devices.

  17. Systolic arrays

    SciTech Connect

    Moore, W.R.; McCabe, A.P.H.; Vrquhart, R.B.

    1987-01-01

    Selected Contents of this book are: Efficient Systolic Arrays for the Solution of Toeplitz Systems, The Derivation and Utilization of Bit Level Systolic Array Architectures, an Efficient Systolic Array for Distance Computation Required in a Video-Codec Based Motion-Detection, On Realizations of Least-Squares Estimation and Kalman Filtering by Systolic Arrays, and Comparison of Systolic and SIMD Architectures for Computer Vision Computations.

  18. Nanocylinder arrays

    DOEpatents

    Tuominen, Mark; Schotter, Joerg; Thurn-Albrecht, Thomas; Russell, Thomas P.

    2007-03-13

    Pathways to rapid and reliable fabrication of nanocylinder arrays are provided. Simple methods are described for the production of well-ordered arrays of nanopores, nanowires, and other materials. This is accomplished by orienting copolymer films and removing a component from the film to produce nanopores, that in turn, can be filled with materials to produce the arrays. The resulting arrays can be used to produce nanoscale media, devices, and systems.

  19. Nanocylinder arrays

    DOEpatents

    Tuominen, Mark; Schotter, Joerg; Thurn-Albrecht, Thomas; Russell, Thomas P.

    2009-08-11

    Pathways to rapid and reliable fabrication of nanocylinder arrays are provided. Simple methods are described for the production of well-ordered arrays of nanopores, nanowires, and other materials. This is accomplished by orienting copolymer films and removing a component from the film to produce nanopores, that in turn, can be filled with materials to produce the arrays. The resulting arrays can be used to produce nanoscale media, devices, and systems.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Design and fabrication of multi-channel photodetector array monolithic with arrayed waveguide grating

    NASA Astrophysics Data System (ADS)

    Qian-Qian, Lv; Pan, Pan; Han, Ye; Dong-Dong, Yin; Yu-Bing, Wang; Xiao-Hong, Yang; Qin, Han

    2016-03-01

    We have provided optical simulations of the evanescently coupled waveguide photodiodes integrated with a 13-channels AWGs. The photodiode could exhibit high internal efficiency by appropriate choice of layers geometry and refractive index. Aseamless joint structure has been designed and fabricated for integrating the output waveguides of AWGs with the evanescently coupled waveguide photodiode array. The highest simulation quantum efficiency could achieve 92% when the matching layer thickness of the PD is 120 nm and the insertion length is 2 μm. The fabricated PD with 320-nm-thick matching layer and 2-μm-length insertion matching layer present a responsivity of 0.87 A/W. Project supported by the National High Technology Research and Development Program of China (Grant Nos. 2013AA031401, 2015AA016902, and 2015AA016904), the National Natural Science Foundation of China (Grant Nos. 61176053, 61274069, and 61435002), and the National Basic Research Program of China (Grant Nos. 2012CB933503 and 2013CB932904).

  8. 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

  9. Micromolar 4-aminopyridine enhances invasion of a vertebrate neurosecretory terminal arborization: optical recording of action potential propagation using an ultrafast photodiode-MOSFET camera and a photodiode array

    PubMed Central

    1996-01-01

    Modulation of the amount of neuropeptide released from a neurosecretory tissue may be achieved by different means. These include alterations in the quantity secreted from each active nerve terminal or in the actual number of terminals activated. From the vertebrate hypothalamus, magnocellular neurons project their axons as bundles of fibers through the median eminence and infundibular stalk to arborize extensively and terminate in the neurohypophysis, where the neurohypophysial peptides and proteins are released into the circulation by a Ca-dependent mechanism. Elevating [Ca2+]o increases the magnitude of an intrinsic optical change in the neurohypophysial terminals that is intimately related to the quantity of neuropeptide released. Similarly, the addition of micromolar concentrations of 4-aminopyridine to the bathing solution enhances this change in large angle light scattering. However, we show here that, while these effects are superficially similar, they reflect different mechanisms of action. Evidence from intrinsic optical signals (light scattering) and extrinsic (potentiometric dye) absorption changes suggests that calcium increases the amount of neuropeptide released from each active terminal in the classical manner, while 4-aminopyridine exerts its secretagogue action by enhancing the invasion of action potentials into the magno-cellular neuron's terminal arborization, increasing the actual number of terminals activated. Physiologically, electrical invasion of the complex terminal arborization in the neurohypophysis may represent an extremely sensitive control point for modulation of peptide secretion. This would be especially effective in a neurohaemal organ like the posterior pituitary, where, in contrast with a collection of presynaptic terminals, the precise location of release is less important than the quantity released. PMID:8868047

  10. A novel PIN photodetector with double linear arrays for rainfall prediction

    NASA Astrophysics Data System (ADS)

    Yan, Yao; Xiong, Liu; Li, Yuan; Zhaohua, Zhang; Tianling, Ren

    2015-09-01

    A novel PIN (positive-intrinsic-negative) photodetector with double linear arrays that can be used to measure the diameter of precipitation particles and the space between two droplets in clouds is proposed. The sensitive unit is the PIN photodiode. The chip with a size of 10 × 8 mm2 has 128 photodiodes, and each row has 64 photodiodes. The device design, fabrication process and package are introduced in the paper. The photocurrent of the packaged chip was systematically tested with a red laser. Also the diameter of one water drop and the space between two water drops were measured. The minimum raindrop diameter which can be tested in this paper is 100 μm. This device can be useful for rainfall prediction. Project supported by the National Natural Science Foundation of China (No. 61434001) and the ‘Thousands Talents’ Program for Pioneer Researchers and Its Innovation Team, China.

  11. Characterization of novel Hamamatsu Multi Pixel Photon Counter (MPPC) arrays for the GlueX experiment

    SciTech Connect

    Soto, Orlando; Rojas, Rimsky; Kuleshov, Sergey V.; Hakobyan, Hayk; Toro, Alam; Brooks, William K.

    2013-12-01

    The novel Hamamatsu Multi Pixel Photon Counter Array S12045(X) is an array of 16 individual MPPCs (3x3 mm{sup 2}) (further in the paper MPPC array channel) each with 3600 G-APD (Geiger-mode Avalanche Photodiodes) pixels (50x50 [{micro}m{sup 2}]). Each MPPC in the array works with its individual reverse bias voltage mode (around 70 V). The paper summarizes the characterization process of MPPC arrays used in GlueX experiment (Hall D, Jefferson Lab). We studied the main features of each MPPC array channel for 2800 MPPC arrays at different temperatures. Two measurement stations were built to extract gain, breakdown voltage, photo detection efficiency (PDE), optical crosstalk and dark rate for each MPPC array channel. The hardware and the data analysis are described, which includes new analytical expressions to obtain the mean number of photo-electrons and optical crosstalk. The dynamical behavior of characterization parameters is presented as well.

  12. Ultraviolet photodetectors and imaging arrays based on III-V nitride heterostructures

    NASA Astrophysics Data System (ADS)

    Brown, Jeffrey David

    2000-10-01

    The III-V nitride class of compound semiconductors has received much attention in the last decade. These materials have a wide, direct bandgap, making them a prime candidate for optoelectronic devices in the blue, green, and ultraviolet spectral regions. These materials exhibit impressive optical, electrical, and thermal properties, even though there are fundamental materials issues that are thus far unresolved. This work explores the application of III-V nitride semiconductors to optical detectors in the ultraviolet region of the electromagnetic spectrum. Metalorganic vapor phase epitaxy was used to synthesize thin film p-i-n photodiode structures on double side polished sapphire substrates; these films were characterized for optical, electrical and structural properties. The grown structures were designed to respond to a predetermined region of the UV spectrum when illuminated from the substrate side. These structures were fabricated into devices using generally accepted techniques for dry etching and p and n-contact metallizations. Test devices were characterized using tools developed by the author. These devices demonstrated as high as 80% quantum efficiency and extremely low dark currents; resulting in spectral detectivities as large as 6 * 1013 cmHz1/2W-1. Devices were designed and demonstrated for a series of detection regions ranging from 365 nm to 250 nm. Photolithography masks were designed to allow the fabrication of photodiode arrays that would hybridize to commercially available CMOS based readout integrated circuits (ROICs), used routinely for infrared photodiode imaging. Photodiode arrays were fabricated and indium bumps were deposited onto the diode contacts and the ROICs to provide electrical connection. The hybrid detector arrays were placed in leadless chip carriers, wirebonded, and connected to commercially available drive and readout circuitry. Images of UV scenes were focused onto the arrays using fused quartz lenses. These images and movies

  13. 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

  14. 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.

  15. Type II superlattice infrared focal plane arrays: Optical, electrical, and mid-wave infrared imaging characterization.

    NASA Astrophysics Data System (ADS)

    Little, John; Svensson, Stefan; Goldberg, Arnie; Kennerly, Steve; Olver, Kim; Hongsmatip, Trirat; Winn, Michael; Uppal, Parvez

    2006-03-01

    We have studied the infrared optical and temperature dependent electrical properties of 320 x 256 arrays of GaSb/InAs type II superlattice infrared photodiodes. Good agreement between single-pixel and focal plane array measurements of the photon-to- electron/hole conversion efficiency was obtained, and the infrared absorption coefficient extracted from these measurements was found to be comparable to that of HgCdTe with the same bandgap as the type II superlattice. Temperature and voltage dependent dark current measurements and the voltage dependent photocurrent generated by a 300 K background scene were described well using a semi-empirical model of the photodiode. We will show high-quality images obtained from the mid-infrared focal plane array operating at 78 K.

  16. Downsampling Photodetector Array with Windowing

    NASA Technical Reports Server (NTRS)

    Patawaran, Ferze D.; Farr, William H.; Nguyen, Danh H.; Quirk, Kevin J.; Sahasrabudhe, Adit

    2012-01-01

    In a photon counting detector array, each pixel in the array produces an electrical pulse when an incident photon on that pixel is detected. Detection and demodulation of an optical communication signal that modulated the intensity of the optical signal requires counting the number of photon arrivals over a given interval. As the size of photon counting photodetector arrays increases, parallel processing of all the pixels exceeds the resources available in current application-specific integrated circuit (ASIC) and gate array (GA) technology; the desire for a high fill factor in avalanche photodiode (APD) detector arrays also precludes this. Through the use of downsampling and windowing portions of the detector array, the processing is distributed between the ASIC and GA. This allows demodulation of the optical communication signal incident on a large photon counting detector array, as well as providing architecture amenable to algorithmic changes. The detector array readout ASIC functions as a parallel-to-serial converter, serializing the photodetector array output for subsequent processing. Additional downsampling functionality for each pixel is added to this ASIC. Due to the large number of pixels in the array, the readout time of the entire photodetector is greater than the time between photon arrivals; therefore, a downsampling pre-processing step is done in order to increase the time allowed for the readout to occur. Each pixel drives a small counter that is incremented at every detected photon arrival or, equivalently, the charge in a storage capacitor is incremented. At the end of a user-configurable counting period (calculated independently from the ASIC), the counters are sampled and cleared. This downsampled photon count information is then sent one counter word at a time to the GA. For a large array, processing even the downsampled pixel counts exceeds the capabilities of the GA. Windowing of the array, whereby several subsets of pixels are designated

  17. Epitaxial growth of HgCdTe 1.55-um avalanche photodiodes by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    de Lyon, Terence J.; Baumgratz, B.; Chapman, G. R.; Gordon, E.; Hunter, Andrew T.; Jack, Michael D.; Jensen, John E.; Johnson, W.; Johs, Blaine D.; Kosai, K.; Larsen, W.; Olson, G. L.; Sen, M.; Walker, B.

    1999-04-01

    Separate absorption and multiplication avalanche photodiode (SAM-APD) device structures, operating in the 1.1 - 1.6 micrometer spectral range, have been fabricated in the HgCdTe material system by molecular-beam epitaxy. These HgCdTe device structures, which offer an alternative technology to existing III-V APD detectors, were grown on CdZnTe(211)B substrates using CdTe, Te, and Hg sources with in situ In and As doping. The alloy composition of the HgCdTe layers was adjusted to achieve both efficient absorption of IR radiation in the 1.1 - 1.6 micrometer spectral range and low excess-noise avalanche multiplication. To achieve resonant enhancement of hole impact ionization from the split-off valence band, the Hg(subscript 1-x)Cd(subscript x)Te alloy composition in the gain region of the device, x equals 0.73, was chosen to achieve equality between the bandgap energy and spin-orbit splitting. The appropriate value of this alloy composition was determined from analysis of the 300 K bandgap and spin-orbit splitting energies of a set of calibration layers, using a combination of IR transmission and spectroscopic ellipsometry measurements. MBE-grown APD epitaxial wafers were processed into passivated mesa-type discrete device structures and diode mini-arrays using conventional HgCdTe process technology. Device spectral response, dark current density, and avalanche gain measurements were performed on discrete diodes and diode mini- arrays on the processed wafers. Avalanche gains in the range of 30 - 40 at reverse bias of 85 - 90 V and array-median dark current density below 2 X 10(superscript -4) A/cm(superscript 2) at 40 V reverse bias have been demonstrated.

  18. 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

  19. PRECISE THROUGHPUT DETERMINATION OF THE PanSTARRS TELESCOPE AND THE GIGAPIXEL IMAGER USING A CALIBRATED SILICON PHOTODIODE AND A TUNABLE LASER: INITIAL RESULTS

    SciTech Connect

    Stubbs, Christopher W.; Doherty, Peter; Cramer, Claire; Narayan, Gautham; Brown, Yorke J.; Lykke, Keith R.; Woodward, John T.; Tonry, John L.

    2010-12-15

    We have used a precision-calibrated photodiode as the fundamental metrology reference in order to determine the relative throughput of the PanSTARRS telescope and the Gigapixel imager, from 400 nm to 1050 nm. Our technique uses a tunable laser as a source of illumination on a transmissive flat-field screen. We determine the full-aperture system throughput as a function of wavelength, including (in a single integral measurement) the mirror reflectivity, the transmission functions of the filters and the corrector optics, and the detector quantum efficiency, by comparing the light seen by each pixel in the CCD array to that measured by a precision-calibrated silicon photodiode. This method allows us to determine the relative throughput of the entire system as a function of wavelength, for each pixel in the instrument, without observations of celestial standards. We present promising initial results from this characterization of the PanSTARRS system, and we use synthetic photometry to assess the photometric perturbations due to throughput variation across the field of view.

  20. Four-layer depth-of-interaction PET detector for high resolution PET using a multi-pixel S8550 avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Nishikido, Fumihiko; Inadama, Naoko; Oda, Ichiro; Shibuya, Kengo; Yoshida, Eiji; Yamaya, Taiga; Kitamura, Keishi; Murayama, Hideo

    2010-09-01

    Avalanche photodiodes (APDs) are being used as photodetectors in positron emission tomography (PET) because they have many advantages over photomultipliers (PMTs) typically used in PET detectors. We have developed a PET detector that consists of a multi-pixel APD and a 6×6×4 array of 1.46×1.46 mm 2×4.5 m LYSO crystals for a small animal PET scanner. The detector can identify four-layer depth of interaction (DOI) with a position-sensitive APD coupled to the backside of a crystal array by just an optimized reflector arrangement. Since scintillation lights are shared among many pixels by the method, weaker signals in APD pixels far from the interacting crystals are affected by noise. To evaluate the performance of the four-layer DOI detector with the APD and the influence of electrical noise on our method, we constructed a prototype DOI detector and tested its performance. We found, except for crystal elements on the edge of the crystal array, all crystal elements could be identified from the 2D position histogram. An energy resolution of 16.9% was obtained for the whole crystal array of the APD detector. The results of noise dependence of detector performances indicated that the DOI detector using the APD could achieve sufficient performance even when using application-specific integrated circuits.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Breadboard linear array scan imager using LSI solid-state technology

    NASA Technical Reports Server (NTRS)

    Tracy, R. A.; Brennan, J. A.; Frankel, D. G.; Noll, R. E.

    1976-01-01

    The performance of large scale integration photodiode arrays in a linear array scan (pushbroom) breadboard was evaluated for application to multispectral remote sensing of the earth's resources. The technical approach, implementation, and test results of the program are described. Several self scanned linear array visible photodetector focal plane arrays were fabricated and evaluated in an optical bench configuration. A 1728-detector array operating in four bands (0.5 - 1.1 micrometer) was evaluated for noise, spectral response, dynamic range, crosstalk, MTF, noise equivalent irradiance, linearity, and image quality. Other results include image artifact data, temporal characteristics, radiometric accuracy, calibration experience, chip alignment, and array fabrication experience. Special studies and experimentation were included in long array fabrication and real-time image processing for low-cost ground stations, including the use of computer image processing. High quality images were produced and all objectives of the program were attained.

  11. 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.

  12. 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.

  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. 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)

  15. 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.

  16. 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.

  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. Integrated array of 2-μm antimonide-based single-photon counting devices.

    PubMed

    Diagne, M A; Greszik, M; Duerr, E K; Zayhowski, J J; Manfra, M J; Bailey, R J; Donnelly, J P; Turner, G W

    2011-02-28

    A 32x32 Sb-based Geiger-mode (GM) avalanche photodiode array, operating at 2 μm with three-dimensional imaging capability, is presented. The array is interfaced with a ROIC (readout integrated circuit) in which each pixel can detect a photon and record the arrival time. The hybridized unit for the 1000-element focal plane array, when operated at 77K with 1 V overbias range, shows an average dark count rate of 1.5 kHz. Three-dimensional range images of objects were acquired. PMID:21369250

  20. Interagency arraying

    NASA Astrophysics Data System (ADS)

    Cox, Henry G.

    Activities performed to match ground aperture requirements for the Neptune encounter in August 1989 with the expected capabilities of the JPL Deep Space Network (DSN) are discussed. Ground aperture requirements, DSN capabilities, and the capabilities of other agencies are reviewed. The design and configurations of the receiver subsystem, combiner subsystem, monitor and control subsystem, recording subsystem, and supporting subsystems are described. The implementation of the Very Large Array-Goldstone Telemetry Array is discussed, and the differences involved with the Parkes-Canberra Telemetry Array implementation are highlighted. The operational concept is addressed.

  1. Enthalpy arrays

    NASA Astrophysics Data System (ADS)

    Torres, Francisco E.; Kuhn, Peter; de Bruyker, Dirk; Bell, Alan G.; Wolkin, Michal V.; Peeters, Eric; Williamson, James R.; Anderson, Gregory B.; Schmitz, Gregory P.; Recht, Michael I.; Schweizer, Sandra; Scott, Lincoln G.; Ho, Jackson H.; Elrod, Scott A.; Schultz, Peter G.; Lerner, Richard A.; Bruce, Richard H.

    2004-06-01

    We report the fabrication of enthalpy arrays and their use to detect molecular interactions, including protein-ligand binding, enzymatic turnover, and mitochondrial respiration. Enthalpy arrays provide a universal assay methodology with no need for specific assay development such as fluorescent labeling or immobilization of reagents, which can adversely affect the interaction. Microscale technology enables the fabrication of 96-detector enthalpy arrays on large substrates. The reduction in scale results in large decreases in both the sample quantity and the measurement time compared with conventional microcalorimetry. We demonstrate the utility of the enthalpy arrays by showing measurements for two protein-ligand binding interactions (RNase A + cytidine 2'-monophosphate and streptavidin + biotin), phosphorylation of glucose by hexokinase, and respiration of mitochondria in the presence of 2,4-dinitrophenol uncoupler.

  2. Array tomography: production of arrays.

    PubMed

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time consuming and require some practice to perfect. This protocol describes the sectioning of embedded tissues and the mounting of the serial arrays. The procedures require some familiarity with the techniques used for ultramicrotome sectioning for electron microscopy. PMID:21041397

  3. Array tomography: imaging stained arrays.

    PubMed

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time-consuming and require some practice to perfect. In this protocol, tissue arrays are imaged using conventional wide-field fluorescence microscopy. Images can be captured manually or, with the appropriate software and hardware, the process can be automated. PMID:21041399

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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%.

  10. 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.

  11. 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.

  12. 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.

  13. Double-layer electrode based on TiO2 nanotubes arrays for enhancing photovoltaic properties in dye-sensitized solar cells.

    PubMed

    He, Zuoli; Que, Wenxiu; Sun, Peng; Ren, Jiangbo

    2013-12-26

    The present work reports a rapid and facile method to fabricate a novel double-layer TiO2 photoanode, which is based on highly ordered TiO2 nanotube arrays and monodispersive scattering microspheres. This double-layer TiO2 sphere/TNTA photoanode have got many unique structural and optical properties from TiO2 scattering microspheres, such as high specific surface area, multiple interparticle scattering, and efficient light-harvesting. Results indicate that this as-fabricated double-layer TiO2 sphere/TNTA front-illumination dye-sensitized solar cell, which is fabricated from the TiO2 nanotube arrays with a 17.4 μm length after TiCl4 treatment, exhibits a pronounced power conversion efficiency of 7.24% under an AM1.5 G irradiation, which can be attributed to the increased incident photon-to-current conversion and light-harvesting efficiency. PMID:24304127

  14. A bench-top megavoltage fan-beam CT using CdWO4-photodiode detectors. I. System description and detector characterization.

    PubMed

    Rathee, S; Tu, D; Monajemi, T T; Rickey, D W; Fallone, B G

    2006-04-01

    We describe the components of a bench-top megavoltage computed tomography (MVCT) scanner that uses an 80-element detector array consisting of CdWO4 scintillators coupled to photodiodes. Each CdWO4 crystal is 2.75 x 8 x 10 mm3. The detailed design of the detector array, timing control, and multiplexer are presented. The detectors show a linear response to dose (dose rate was varied by changing the source to detector distance) with a correlation coefficient (R2) nearly unity with the standard deviation of signal at each dose being less than 0.25%. The attenuation of a 6 MV beam by solid water measured by this detector array indicates a small, yet significant spectral hardening that needs to be corrected before image reconstruction. The presampled modulation transfer function is strongly affected by the detector's large pitch and a large improvement can be obtained by reducing the detector pitch. The measured detective quantum efficiency at zero spatial frequency is 18.8% for 6 MV photons which will reduce the dose to the patient in MVCT applications. The detector shows a less than a 2% reduction in response for a dose of 24.5 Gy accumulated in 2 h; however, the lost response is recovered on the following day. A complete recovery can be assumed within the experimental uncertainty (standard deviation <0.5%); however, any smaller permanent damage could not be assessed. PMID:16696485

  15. A bench-top megavoltage fan-beam CT using CdWO{sub 4}-photodiode detectors. I. System description and detector characterization

    SciTech Connect

    Rathee, S.; Tu, D.; Monajemi, T.T.; Rickey, D.W.; Fallone, B.G.

    2006-04-15

    We describe the components of a bench-top megavoltage computed tomography (MVCT) scanner that uses an 80-element detector array consisting of CdWO{sub 4} scintillators coupled to photodiodes. Each CdWO{sub 4} crystal is 2.75x8x10 mm{sup 3}. The detailed design of the detector array, timing control, and multiplexer are presented. The detectors show a linear response to dose (dose rate was varied by changing the source to detector distance) with a correlation coefficient (R{sup 2}) nearly unity with the standard deviation of signal at each dose being less than 0.25%. The attenuation of a 6 MV beam by solid water measured by this detector array indicates a small, yet significant spectral hardening that needs to be corrected before image reconstruction. The presampled modulation transfer function is strongly affected by the detector's large pitch and a large improvement can be obtained by reducing the detector pitch. The measured detective quantum efficiency at zero spatial frequency is 18.8% for 6 MV photons which will reduce the dose to the patient in MVCT applications. The detector shows a less than a 2% reduction in response for a dose of 24.5 Gy accumulated in 2 h; however, the lost response is recovered on the following day. A complete recovery can be assumed within the experimental uncertainty (standard deviation <0.5%); however, any smaller permanent damage could not be assessed.

  16. Pixel multiplexing technique for real-time three-dimensional-imaging laser detection and ranging system using four linear-mode avalanche photodiodes.

    PubMed

    Xu, Fan; Wang, Yuanqing; Li, Fenfang

    2016-03-01

    The avalanche-photodiode-array (APD-array) laser detection and ranging (LADAR) system has been continually developed owing to its superiority of nonscanning, large field of view, high sensitivity, and high precision. However, how to achieve higher-efficient detection and better integration of the LADAR system for real-time three-dimensional (3D) imaging continues to be a problem. In this study, a novel LADAR system using four linear mode APDs (LmAPDs) is developed for high-efficient detection by adopting a modulation and multiplexing technique. Furthermore, an automatic control system for the array LADAR system is proposed and designed by applying the virtual instrumentation technique. The control system aims to achieve four functions: synchronization of laser emission and rotating platform, multi-channel synchronous data acquisition, real-time Ethernet upper monitoring, and real-time signal processing and 3D visualization. The structure and principle of the complete system are described in the paper. The experimental results demonstrate that the LADAR system is capable of achieving real-time 3D imaging on an omnidirectional rotating platform under the control of the virtual instrumentation system. The automatic imaging LADAR system utilized only 4 LmAPDs to achieve 256-pixel-per-frame detection with by employing 64-bit demodulator. Moreover, the lateral resolution is ∼15 cm and range accuracy is ∼4 cm root-mean-square error at a distance of ∼40 m. PMID:27036763

  17. Pixel multiplexing technique for real-time three-dimensional-imaging laser detection and ranging system using four linear-mode avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Xu, Fan; Wang, Yuanqing; Li, Fenfang

    2016-03-01

    The avalanche-photodiode-array (APD-array) laser detection and ranging (LADAR) system has been continually developed owing to its superiority of nonscanning, large field of view, high sensitivity, and high precision. However, how to achieve higher-efficient detection and better integration of the LADAR system for real-time three-dimensional (3D) imaging continues to be a problem. In this study, a novel LADAR system using four linear mode APDs (LmAPDs) is developed for high-efficient detection by adopting a modulation and multiplexing technique. Furthermore, an automatic control system for the array LADAR system is proposed and designed by applying the virtual instrumentation technique. The control system aims to achieve four functions: synchronization of laser emission and rotating platform, multi-channel synchronous data acquisition, real-time Ethernet upper monitoring, and real-time signal processing and 3D visualization. The structure and principle of the complete system are described in the paper. The experimental results demonstrate that the LADAR system is capable of achieving real-time 3D imaging on an omnidirectional rotating platform under the control of the virtual instrumentation system. The automatic imaging LADAR system utilized only 4 LmAPDs to achieve 256-pixel-per-frame detection with by employing 64-bit demodulator. Moreover, the lateral resolution is ˜15 cm and range accuracy is ˜4 cm root-mean-square error at a distance of ˜40 m.

  18. 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.

  19. Microlens arrays

    NASA Astrophysics Data System (ADS)

    Hutley, Michael C.; Stevens, Richard F.; Daly, Daniel J.

    1992-04-01

    Microlenses have been with us for a long time as indeed the very word lens reminds us. Many early lenses,including those made by Hooke and Leeuwenhoek in the 17th century were small and resembled lentils. Many languages use the same word for both (French tilentillelt and German "Linse") and the connection is only obscure in English because we use the French word for the vegetable and the German for the optic. Many of the applications for arrays of inicrolenses are also well established. Lippmann's work on integral photography at the turn of the century required lens arrays and stimulated an interest that is very much alive today. At one stage, lens arrays played an important part in high speed photography and various schemes have been put forward to take advantage of the compact imaging properties of combinations of lens arrays. The fact that many of these ingenious schemes have not been developed to their full potential has to a large degree been due to the absence of lens arrays of a suitable quality and cost.

  20. Modulation Transfer Function Measurement of Infrared Focal-Plane Arrays with Small Fill Factors

    NASA Astrophysics Data System (ADS)

    de la Barrière, Florence; Druart, Guillaume; Guérineau, Nicolas; Rommeluère, Sylvain; Mugnier, Laurent; Gravrand, Olivier; Baier, Nicolas; Lhermet, Nicolas; Destefanis, Gérard; Derelle, Sophie

    2012-10-01

    This paper describes an original method to measure the modulation transfer function (MTF) of an infrared focal-plane array (IRFPA), based on a diffraction grating called a continuously self-imaging grating (CSIG). We give a general methodology to design the test bench, and we describe the data processing approach which has been developed to extract relevant information about the size of the photodiodes and filtering effects. The MTF measurement capability of this method is illustrated with a cooled IRFPA.

  1. A comparison of imaging methods for use in an array biosensor

    NASA Technical Reports Server (NTRS)

    Golden, Joel P.; Ligler, Frances S.

    2002-01-01

    An array biosensor has been developed which uses an actively-cooled, charge-coupled device (CCD) imager. In an effort to save money and space, a complementary metal-oxide semiconductor (CMOS) camera and photodiode were tested as replacements for the cooled CCD imager. Different concentrations of CY5 fluorescent dye in glycerol were imaged using the three different detection systems with the same imaging optics. Signal discrimination above noise was compared for each of the three systems.

  2. Design of solid state neutral particle analyzer array for National Spherical Torus Experiment-Upgrade

    SciTech Connect

    Liu, D. Heidbrink, W. W.; Zhu, Y. B.; Tritz, K.; Roquemore, A. L.; Medley, S. S.

    2014-11-15

    A new compact, multi-channel Solid State Neutral Particle Analyzer (SSNPA) diagnostic based on silicon photodiode array has been designed and is being fabricated for the National Spherical Torus Experiment-Upgrade (NSTX-U). The SSNPA system utilizes a set of vertically stacked photodiode arrays in current mode viewing the same plasma region with different filter thickness to obtain fast temporal resolution (∼120 kHz bandwidth) and coarse energy information in three bands of >25 keV, >45 keV, and >65 keV. The SSNPA system consists of 15 radial sightlines that intersect existing on-axis neutral beams at major radii between 90 and 130 cm, 15 tangential sightlines that intersect new off-axis neutral beams at major radii between 120 and 145 cm. These two subsystems aim at separating the response of passing and trapped fast ions. In addition, one photodiode array whose viewing area does not intersect any neutral beams is used to monitor passive signals produced by fast ions that charge exchange with background neutrals.

  3. Global Arrays

    SciTech Connect

    2006-02-23

    The Global Arrays (GA) toolkit provides an efficient and portable “shared-memory” programming interface for distributed-memory computers. Each process in a MIMD parallel program can asynchronously access logical blocks of physically distributed dense multi-dimensional arrays, without need for explicit cooperation by other processes. Unlike other shared-memory environments, the GA model exposes to the programmer the non-uniform memory access (NUMA) characteristics of the high performance computers and acknowledges that access to a remote portion of the shared data is slower than to the local portion. The locality information for the shared data is available, and a direct access to the local portions of shared data is provided. Global Arrays have been designed to complement rather than substitute for the message-passing programming model. The programmer is free to use both the shared-memory and message-passing paradigms in the same program, and to take advantage of existing message-passing software libraries. Global Arrays are compatible with the Message Passing Interface (MPI).

  4. Pacific Array

    NASA Astrophysics Data System (ADS)

    Kawakatsu, H.; Takeo, A.; Isse, T.; Nishida, K.; Shiobara, H.; Suetsugu, D.

    2014-12-01

    Based on our recent results on broadband ocean bottom seismometry, we propose a next generation large-scale array experiment in the ocean. Recent advances in ocean bottom broadband seismometry (e.g., Suetsugu & Shiobara, 2014, Annual Review EPS), together with advances in the seismic analysis methodology, have now enabled us to resolve the regional 1-D structure of the entire lithosphere/asthenosphere system, including seismic anisotropy (both radial and azimuthal), with deployments of ~10-15 broadband ocean bottom seismometers (BBOBSs) (namely "ocean-bottom broadband dispersion survey"; Takeo et al., 2013, JGR; Kawakatsu et al., 2013, AGU; Takeo, 2014, Ph.D. Thesis; Takeo et al., 2014, JpGU). Having ~15 BBOBSs as an array unit for 2-year deployment, and repeating such deployments in a leap-frog way (an array of arrays) for a decade or so would enable us to cover a large portion of the Pacific basin. Such efforts, not only by giving regional constraints on the 1-D structure, but also by sharing waveform data for global scale waveform tomography, would drastically increase our knowledge of how plate tectonics works on this planet, as well as how it worked for the past 150 million years. International collaborations might be sought.

  5. Global Arrays

    Energy Science and Technology Software Center (ESTSC)

    2006-02-23

    The Global Arrays (GA) toolkit provides an efficient and portable “shared-memory” programming interface for distributed-memory computers. Each process in a MIMD parallel program can asynchronously access logical blocks of physically distributed dense multi-dimensional arrays, without need for explicit cooperation by other processes. Unlike other shared-memory environments, the GA model exposes to the programmer the non-uniform memory access (NUMA) characteristics of the high performance computers and acknowledges that access to a remote portion of the sharedmore » data is slower than to the local portion. The locality information for the shared data is available, and a direct access to the local portions of shared data is provided. Global Arrays have been designed to complement rather than substitute for the message-passing programming model. The programmer is free to use both the shared-memory and message-passing paradigms in the same program, and to take advantage of existing message-passing software libraries. Global Arrays are compatible with the Message Passing Interface (MPI).« less

  6. Evaluation of Photodiode and Thermopile Pyranometers for Photovoltaic Applications: Preprint

    SciTech Connect

    Sengupta, M.; Gotseff, P.; Stoffel, T.

    2012-09-01

    Accurately determining PV module performance in the field requires measurement of solar irradiance reaching the PV panel at a high level of accuracy and known uncertainty. Silicon detectors used in various solar energy measuring instruments including reference cells are potentially an attractive choice for multiple reasons that include faster responsivity than thermopile detectors, cheaper cost and lower maintenance. The main drawback though is the fact that the silicon detectors are only spectrally responsive in a narrow part of the solar spectrum. Therefore, to determine broadband solar irradiance a calibration factor that converts the narrowband response to broadband is required. Normally this calibration factor is a single number determined under standard conditions but then used for various scenarios including varying air-mass, panel orientation and atmospheric conditions. This would not have been an issue if all wavelengths that form the broadband spectrum responded uniformly to atmospheric constituents. Unfortunately the scattering and absorption signature varies widely across wavelengths and the calibration factor computed under certain test conditions is not appropriate for other conditions. This paper lays out the issues that will arise from the use of silicon detectors for PV performance measurement in the field. We also present a comparison of simultaneous spectral and broadband measurements from silicon and thermopile detectors and estimated measurement errors when using silicon devices for both array performance and resource assessment.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Solar-blind AlGaN 256x256 p-i-n detectors and focal plane arrays

    NASA Astrophysics Data System (ADS)

    Reine, M. B.; Hairston, A.; Lamarre, P.; Wong, K. K.; Tobin, S. P.; Sood, A. K.; Cooke, C.; Pophristic, M.; Guo, S.; Peres, B.; Singh, R.; Eddy, C. R., Jr.; Chowdhury, U.; Wong, M. M.; Dupuis, R. D.; Li, T.; DenBaars, S. P.

    2006-02-01

    This paper reports the development of aluminum-gallium nitride (AlGaN or Al xGa 1-xN) photodiode technology for high-operability 256×256 hybrid Focal Plane Arrays (FPAs) for solar-blind ultraviolet (UV) detection in the 260-280 nm spectral region. These hybrid UV FPAs consist of a 256×256 back-illuminated AlGaN p-i-n photodiode array, operating at zero bias voltage, bump-mounted to a matching 256×256 silicon CMOS readout integrated circuit (ROIC) chip. The unit cell size is 30×30 μm2. The photodiode arrays were fabricated from multilayer AlGaN films grown by MOCVD on 2" dia. UV-transparent sapphire substrates. Improvements in AlGaN material growth and device design enabled high quantum efficiency and extremely low leakage current to be achieved in high-operability 256×256 p-i-n photodiode arrays with cuton and cutoff wavelengths of 260 and 280 nm, placing the response in the solar-blind wavelength region (less than about 280 nm) where solar radiation is heavily absorbed by the ozone layer. External quantum efficiencies (at V=0, 270 nm, no antireflection coating) as high as 58% were measured in backilluminated devices. A number of 256×256 FPAs, with the AlGaN arrays fabricated from films grown at three different facilities, achieved response operabilities as high as 99.8%, response nonuniformities (σ/μ) as low as 2.5%, and zero-bias resistance median values as high as 1×10 16 ohm, corresponding to R 0A products of 7×10 10 ohm-cm2. Noise Equivalent Irradiance (NEI) data were measured on these FPAs. Median NEI values at 1 Hz are 250-500 photons/pixel-s, with best-element values as low as 90 photons/pixel-s at 1 Hz.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. Quantification of patulin in fruit leathers by ultra-high-performance liquid chromatography-photodiode array (UPLC-PDA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Patulin is a mycotoxin commonly found in certain fruit and fruit products. For this reason many countries have established regulatory limits pertaining to, in particular, apple juice and apple products. Fruit leathers are produced by dehydrating fruit puree, leaving a sweet product that has a leathe...

  18. Detection of charged particles and X-rays by scintillator layers coupled to amorphous silicon photodiode arrays

    SciTech Connect

    Jing, T.; Drewery, J.; Hong, W.S.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V.; Goodman, C.A.; Wildermuth, D.

    1995-04-01

    Hydrogenated amorphous silicon (a-Si:H) p-i-n diodes with transparent metallic contacts are shown to be suitable for detecting charged particles, electrons, and X-rays. When coupled to a suitable scintillator using CsI(Tl) as the scintillator we show a capability to detect minimum ionizing particles with S/N {approximately}20. We demonstrate such an arrangement by operating a p-i-n diode in photovoltaic mode (reverse bias). Moreover, we show that a p-i-n diode can also work as a photoconductor under forward bias and produces a gain yield of 3-8 higher light sensitivity for shaping times of 1 {mu}s. n-i-n devices have similar optical gain as the p-i-n photoconductor for short integrating times ( < 10{mu}s). However, n-i-n devices exhibit much higher gain for a long term integration (10ms) than the p-i-n ones. High sensitivity photosensors are very desirable for X-ray medical imaging because radiation exposure dose can be reduced significantly. The scintillator CsI layers we made have higher spatial resolution than the Kodak commercial scintillator screens due to their internal columnar structure which can collimate the scintillation light. Evaporated CsI layers are shown to be more resistant to radiation damage than the crystalline bulk CsI(Tl).

  19. Quality evaluation of Houttuynia cordata Thunb. by high performance liquid chromatography with photodiode-array detection (HPLC-DAD).

    PubMed

    Yang, Zhan-nan; Sun, Yi-ming; Luo, Shi-qiong; Chen, Jin-wu; Chen, Jin-wu; Yu, Zheng-wen; Sun, Min

    2014-03-01

    A new, validated method, developed for the simultaneous determination of 16 phenolics (chlorogenic acid, scopoletin, vitexin, rutin, afzelin, isoquercitrin, narirutin, kaempferitrin, quercitrin, quercetin, kaempferol, chrysosplenol D, vitexicarpin, 5-hydroxy-3,3',4',7-tetramethoxy flavonoids, 5-hydroxy-3,4',6,7-tetramethoxy flavonoids and kaempferol-3,7,4'-trimethyl ether) in Houttuynia cordata Thunb. was successfully applied to 35 batches of samples collected from different regions or at different times and their total antioxidant activities (TAAs) were investigated. The aim was to develop a quality control method to simultaneously determine the major active components in H. cordata. The HPLC-DAD method was performed using a reverse-phase C18 column with a gradient elution system (acetonitrile-methanol-water) and simultaneous detection at 345 nm. Linear behaviors of method for all the analytes were observed with linear regression relationship (r(2)>0.999) at the concentration ranges investigated. The recoveries of the 16 phenolics ranged from 98.93% to 101.26%. The samples analyzed were differentiated and classified based on the contents of the 16 characteristic compounds and the TAA using hierarchical clustering analysis (HCA) and principal component analysis (PCA). The results analyzed showed that similar chemical profiles and TAAs were divided into the same group. There was some evidence that active compounds, although they varied significantly, may possess uniform anti-oxidant activities and have potentially synergistic effects. PMID:24577906

  20. Simultaneous Quantitative Determination of 12 Active Components in Yuanhu Zhitong Prescription by RP-HPLC Coupled with Photodiode Array Detection

    PubMed Central

    Zhang, Xiaokai; Zhang, Song; Yang, Qian; Cao, Wei; Xie, Yanhua; Qiu, Pengcheng; Wang, Siwang

    2015-01-01

    Background: Yuanhu Zhitong prescription (YZP) is a famous traditional Chinese medicine formula, which is officially recorded in Chinese Pharmacopoeia for the treatment of stomach pain, hypochondriac pain, headache and dysmenorrhea caused by qi-stagnancy and blood stasis. It is the first report for the simultaneous determination of 12 active components in YZP. Objective: A newly, simple, accurate and reliable method for the separation and determination of 12 active components (protopine, α-allocryptopine, coptisine, xanthotol, palmatine, dehydrocorydaline, glaucine, tetrahydropalmatine, tetrahydroberberine, imperatorin, corydaline, isoimperatorin) in YZP was developed and validated using HPLC-PAD. Materials and Methods: The analytes were performed on a Phenomenex Luna-C18 (2) column (250×4.6 mm, 5.0 μm) with a gradient elution program using a mixture of acetonitrile and 0.1% phosphoric acid water solution (adjusted with triethylamine to pH 5.6) as mobile phase. Analytes were performed at 30°C with a flow rate of 1.0 mL/min. Results: The validated method was applied to analyze four major dosage forms of YZP coming from different manufacturers with good linearity (r2, 0.9981~0.9999), precision (RSD, 0.24~2.89%), repeatability (RSD, 0.15~3.34%), stability (RSD, 0.14~3.35%), recovery (91.13~110.81%) of the 12 components. Conclusion: The proposed method enables the separation and determination of 12 active components in a single run for the quality control of YZP. PMID:25709212

  1. Emerging contaminant determination in water samples by liquid chromatography using a monolithic column coupled with a photodiode array detector.

    PubMed

    Salvatierra-Stamp, Vilma Del C; Ceballos-Magaña, Silvia G; Gonzalez, Jorge; Jurado, Jose M; Muñiz-Valencia, Roberto

    2015-06-01

    Concern about the presence of emerging contaminants in the environment has increased because biological activity at low concentrations has been observed. The difficulty of detecting and quantifying these compounds encourages the development of analytical methods with highly sensitive and selective analytical procedures. Pharmaceuticals, pesticides, and industrial chemicals are used and finally discarded to the environment. This paper provides a rapid and sensitive analytical method for the quantification of eight emerging contaminants (carbamazepine, carbofuran, bisphenol A, diuron, 17 α ethinylestradiol, ametryn, carbazole, and triclosan). A two-level full factorial design for optimization of chromatographic separation and sample preparation was performed. The separation using a monolithic column (Onyx C18) achieved baseline resolution for all compounds in 4.6 min. The optimized sample treatment involved a preconcentration step by means of solid-phase extraction using HF Bond Elut-C18 cartridges, achieving an enrichment factor of 2222. Under optimum conditions, good linearity was obtained with a correlation coefficient higher than 0.999. The limits of detection and quantification for carbamazepine, carbofuran, bisphenol A, diuron, 17 α ethinylestradiol, ametryn, and carbazole were in the range of 0.01-208.7 and 0.03-695.7 ng L(-1), respectively, and for triclosan, the limit of detection and quantification was 0.67 and 2.25 μg L(-1), respectively. Precision evaluated as relative standard deviations was lower than 15 %. The proposed method was found robust. Finally, the method was successfully applied to superficial water samples. PMID:25860655

  2. Installation of soft X-ray array diagnostics and its application to tomography reconstruction using synthetic KSTAR X-ray images.

    PubMed

    Lee, Seung Hun; Jang, Juhyeok; Hong, Joohwan; Pacella, D; Romano, A; Gabellieri, L; Jang, Siwon; Kim, Junghee; Choe, Wonho

    2014-11-01

    Four-array system of soft X-ray diagnostics was installed on KSTAR tokamak. Each array has 32 viewing chords of two photo-diode array detectors with spatial resolution of 2 cm. To estimate signals from the soft X-ray radiation power, typical ne, Te, and argon impurity line radiation profiles in KSTAR are chosen. The photo-diodes were absolutely calibrated as a function of the incident photon energy in 2-40 keV range with a portable X-ray tube. Two-dimensional Te image properties by multi-energy method were simulated and visualized with six combinations of beryllium filter sets within the dynamic range of signal ratio. PMID:25430392

  3. Installation of soft X-ray array diagnostics and its application to tomography reconstruction using synthetic KSTAR X-ray images

    SciTech Connect

    Lee, Seung Hun; Jang, Juhyeok; Hong, Joohwan; Jang, Siwon; Choe, Wonho; Pacella, D.; Romano, A.; Gabellieri, L.; Kim, Junghee

    2014-11-15

    Four-array system of soft X-ray diagnostics was installed on KSTAR tokamak. Each array has 32 viewing chords of two photo-diode array detectors with spatial resolution of 2 cm. To estimate signals from the soft X-ray radiation power, typical n{sub e}, T{sub e}, and argon impurity line radiation profiles in KSTAR are chosen. The photo-diodes were absolutely calibrated as a function of the incident photon energy in 2–40 keV range with a portable X-ray tube. Two-dimensional T{sub e} image properties by multi-energy method were simulated and visualized with six combinations of beryllium filter sets within the dynamic range of signal ratio.

  4. 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.

  5. B+ Ion Implanted n+ on P HgCdTe Photovoltaic Arrays

    NASA Astrophysics Data System (ADS)

    Shi, Yanli

    2005-10-01

    B+ ion implantation technology has been utilized to fabricate n+ on P HgCdTe photovoltaic arrays with the HgCdTe epitaxial materials grown by the liquid phase epitaxial method. The effects of implanting energy and dose on doping profile and approximate junction depth were calculated in detail; the calculated results are well consistent with the measurement results by the second ion mass spectrum experimental technique (SIMS). The 10×10 photodiode arrays in which each pixel size is nominally 20×20 μm2 and the pitch is 30 μm were made to investigate the electro-optic performance of devices. The device characterization such as array uniformity and optical crosstalk was nondestructively investigated using a scanning laser microscope. The two-dimensional maps of laser beam induced current (LBIC) signal have shown good uniformity for the fabricated arrays, and there is no optical crosstalk between the arrays for the B+ ion implantation conditions used at the implanting energy of 130 KeV and the dose of 2×1014 cm2. The primary performance of photodiodes the zero bias dynamic resistance junction area product R0A, infrared response spectrum, and the detectivity D* have been measured, and the typical values for the test photodiodes with cutoff wavelength of 9.2 μm measured at 77°K are: R0A = 13.5'Ω.cm2, average blackbody detectivity D* = 7.18×1010 cm Hz1/2W-1. By further optimizing the implantation conditions and the quality of materials, excellent performances of photovoltaic detectors can be expected.

  6. Semiconductor arrays with multiplexer readout for gamma-ray imaging: results for a 48 × 48 Ge array

    NASA Astrophysics Data System (ADS)

    Barber, H. B.; Augustine, F. L.; Barrett, H. H.; Dereniak, E. L.; Matherson, K. L.; Meyers, T. J.; Perry, D. L.; Venzon, J. E.; Woolfenden, J. M.; Young, E. T.

    1994-12-01

    We are developing a new kind of gamma-ray imaging device that has sub-millimeter spatial resolution and excellent energy resolution. The device is composed of a slab of semiconductor detector partitioned into an array of detector cells by photolithography and connected to a monolithic circuit chip called a multiplexer (MUX) for readout. Our application is for an ultra-high-resolution SPECT system for functional brain imaging using an injected radiotracer. We report here on results obtained with a Hughes 48 × 48 Ge PIN-photodiode array with MUX readout, originally developed as an infrared focal-plane-array imaging sensor. The device functions as an array of individual gamma-ray detectors with minimal interpixel crosstalk. Linearity of energy response is excellent up to at least 140 keV. The array exhibits excellent energy resolution, ˜ 2 keV at ≤ 140 keV or 1.5% FWHM at 140 keV. The energy resolution is dominated by MUX readout noise and so should improve with MUX optimization for gamma-ray detection. The spatial resolution of the 48 × 48 Ge array is essentially the same as the pixel spacing, 125 μm. The quantum efficiency is limited by the thin Ge detector (0.25 mm), but this approach is readily applicable to thicker Ge detectors and room-temperature semiconductor detectors such as CdTe, HgI 2 and CdZnTe.

  7. Solid State Neutral Particle Analyzer Array on NSTX

    SciTech Connect

    K. Shinohara; D.S. Darrow; A.L. Roquemore; S.S. Medley; F.E. Cecil

    2004-05-13

    A Solid State Neutral Particle Analyzer (SSNPA) array has been installed on the National Spherical Torus Experiment (NSTX). The array consists of four chords viewing through a common vacuum flange. The tangency radii of the viewing chords are 60, 90, 100, and 120 cm. They view across the three co-injection neutral beam lines (deuterium, 80 keV (typ.) with tangency radii 48.7, 59.2, and 69.4 cm) on NSTX and detect co-going energetic ions. A silicon photodiode used was calibrated by using a mono-energetic deuteron beam source. Deuterons with energy above 40 keV can be detected with the present setup. The degradation of the performance was also investigated. Lead shots and epoxy are used for neutron shielding to reduce handling any hazardous heavy metal. This method also enables us to make an arbitrary shape to be fit into the complex flight tube.

  8. Arrayed Diagnostic Development on the HyperV Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Brockington, Samuel; Case, Andrew; Messer, Sarah; Bomgardner, Richard; Witherspoon, F. D.

    2008-11-01

    The sparkgap injected plasma accelerator is one of several coaxial railguns constructed at HyperV to accelerate dense plasmas to high velocities. A circumferential array of 112 high voltage tungsten electrodes ablates polyethylene to form and inject a toroidally shaped plasma into the annular breech at the rear of the accelerator. A pulse forming network then applies several hundred kiloamps to the coaxial electrodes to accelerate the plasma. A 4-chord laser deflectometer and a 32-sensor fast photodiode array are being developed to help resolve the structure, density, and velocity of the accelerated plasma jet for different accelerator parameters. We present details of the diagnostic designs and initial data. Work supported by the U.S. DOE Office of Fusion Energy Sciences.

  9. Plasmonic nanohole arrays on Si-Ge heterostructures: an approach for integrated biosensors

    NASA Astrophysics Data System (ADS)

    Augel, L.; Fischer, I. A.; Dunbar, L. A.; Bechler, S.; Berrier, A.; Etezadi, D.; Hornung, F.; Kostecki, K.; Ozdemir, C. I.; Soler, M.; Altug, H.; Schulze, J.

    2016-03-01

    Nanohole array surface plasmon resonance (SPR) sensors offer a promising platform for high-throughput label-free biosensing. Integrating nanohole arrays with group-IV semiconductor photodetectors could enable low-cost and disposable biosensors compatible to Si-based complementary metal oxide semiconductor (CMOS) technology that can be combined with integrated circuitry for continuous monitoring of biosamples and fast sensor data processing. Such an integrated biosensor could be realized by structuring a nanohole array in the contact metal layer of a photodetector. We used Fouriertransform infrared spectroscopy to investigate nanohole arrays in a 100 nm Al film deposited on top of a vertical Si-Ge photodiode structure grown by molecular beam epitaxy (MBE). We find that the presence of a protein bilayer, constitute of protein AG and Immunoglobulin G (IgG), leads to a wavelength-dependent absorptance enhancement of ~ 8 %.

  10. Performance of focal plane arrays for the photon counting arrays (PCAR) program

    NASA Astrophysics Data System (ADS)

    Blessinger, Michael A.; Enriquez, Marlon; Groppe, Joseph V.; Flynn, Kevin; Sudol, Thomas M.; Onat, Bora M.; Kleinhans, William E.

    2007-04-01

    The DARPA PCAR program is sponsoring the development of low noise, near infrared (1.5 μm wavelength) focal plane arrays (FPAs) for night vision applications. The first phase of this work has produced a collection of 640 x 512 pixel, 20 μm pitch FPAs with low noise. The approach was to design four different read out integrated circuits (ROICs), all compatible with the same bump-bonded InGaAs photodiode detector array. Two of the designs have capacitive transimpedance amplifier (CTIA) pixels, each with a somewhat different amplifier design and with two different sizes of small integration capacitors. The third design is a source follower per detector (SFD) pixel, integrating on the detector capacitance. The fourth design also integrates on the detector capacitance, but uses a moderate gain, in-pixel amplifier to boost the signal level, and also has a differential pixel output. All four designs require off-chip correlated sampling to achieve the desired noise level. The correlated sampling is performed digitally in the data acquisition software. Each design is capable of 30 frames per second read out rate, and has a dynamic range of 1000:1 using a rolling, non-snapshot integration. The designs were fabricated in a standard CMOS foundry process, and were bump-bonded to InGaAs detector arrays. All four designs are working without any significant design errors, and are producing low noise imaging, with less than 50 electrons rms noise per pixel after correlated double sampling.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Active pixel sensor array with multiresolution readout

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R. (Inventor); Kemeny, Sabrina E. (Inventor); Pain, Bedabrata (Inventor)

    1999-01-01

    An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node. There is also a readout circuit, part of which can be disposed at the bottom of each column of cells and be common to all the cells in the column. The imaging device can also include an electronic shutter formed on the substrate adjacent the photogate, and/or a storage section to allow for simultaneous integration. In addition, the imaging device can include a multiresolution imaging circuit to provide images of varying resolution. The multiresolution circuit could also be employed in an array where the photosensitive portion of each pixel cell is a photodiode. This latter embodiment could further be modified to facilitate low light imaging.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. Status of very long infrared-wave focal plane array development at DEFIR

    NASA Astrophysics Data System (ADS)

    Gravrand, O.; Chorier, Ph.

    2009-05-01

    The very long infrared wavelength (>14μm) is a very challenging range for the design of large HgCdTe focal plane arrays. As the wavelength gets longer (ie the semiconductor gap gets smaller), the physic of photodiodes asks for numerous technological improvements to keep a high level of detection performance. DEFIR (LETI-Sofradir common research team) has been highly active in this field during the last few years. The need (mainly expressed by the space industry ESA and CNES) of very long wave focal plane arrays appears very demanding in terms of dark current, defect density and of course quantum efficiency. This paper aims at presenting a status of long and very long wave focal plane array development at DEFIR for three different ion implanted technologies: n on p mercury vacancies doped technology, n on p extrinsic doped technology, and p on n arsenic on indium technology. Special focus is done to 15μm cut off n/p focal plane array fabricated in our laboratory demonstrating high uniformity, diffusion and shot noise limited photodiodes at 50K.

  12. 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.

  13. 320x256 solar-blind focal plane arrays based on Al{sub x}Ga{sub 1-x}N

    SciTech Connect

    McClintock, R.; Mayes, K.; Yasan, A.; Shiell, D.; Kung, P.; Razeghi, M.

    2005-01-03

    We report AlGaN-based backilluminated solar-blind ultraviolet focal plane arrays operating at a wavelength of 280 nm. The electrical characteristics of the individual pixels are discussed, and the uniformity of the array is presented. The p-i-n photodiode array was hybridized to a 320x256 read-out integrated circuit entirely within our university research lab, and a working 320x256 camera was demonstrated. Several example solar-blind images from the camera are also provided.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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%.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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).

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. Receiver Performance of CO2 and CH4 Lidar with Low Noise HgCdTe Avalanche Photodiodes

    NASA Astrophysics Data System (ADS)

    Sun, X.; Abshire, J. B.

    2012-12-01

    NASA Goddard Space Flight Center (GSFC) is currently developing CO2 lidars at 1.57 μm wavelength for the Active Sensing of CO2 Emission over Days, Nights, and Seasons (ASCENDS) mission. One of the major technical challenges is the photodetectors that have to operate in short wave infrared (SWIR) wavelength region and sensitive to received laser pulses of only a few photons. We have been using InGaAs photocathode photomultiplier tubes (PMT) in our airborne simulator of the CO2 lidar that can detect single photon with up to 10% quantum efficiency at <1.6 μm wavelength. However it was difficult to maintain a sufficiently wide signal dynamic range and single photon sensitivity at the same time with the PMTs. There may also be a lifetime limitation with the InGaAs photocathode PMT for a multi-year space mission. We have been developing HgCdTe avalanche photodiode (APD) SWIR detector systems with DRS Technologies, Reconnaissance, Surveillance and Target Acquisition (RSTA) Division as an alternative photodetector for our CO2 lidars. The new HgCdTe APDs have typically a >50% quantum efficiency, including the effect of fill-factor, from 0.9 to 4.5 μm wavelength. DRS RSTA will integrate a low noise read-out integrated circuit (ROIC) with the HgCdTe APD array into a low noise analog SWIR detector with near single photon sensitivity. The new HgCdTe APD SWIR detector assembly is expected to improve the receiver sensitivity of our CO2 lidar by at least a factor of two and provide a sufficient wide signal dynamic range. The new SWIR detector systems can also be used in the CH4 lidars at 1.65 μm wavelength currently being developed at GSFC. The near infrared PMTs have diminishing quantum efficiency as the wavelength exceeds 1.6 μm. InGaAs APDs have a high quantum efficiency but too high an excess noise factor to achieve near quantum limited performance. The new HgCdTe APDs is expected to give a much superior performance than the PMTs and the InGaAs APDs. In this paper, we

  13. Optoelectronic properties of photodiodes for the mid-and far-infrared based on the InAs/GaSb/AlSb materials family

    NASA Astrophysics Data System (ADS)

    Fuchs, Frank; Buerkle, L.; Hamid, R.; Herres, N.; Pletschen, Wilfried; Sah, R. E.; Kiefer, Rudolf; Schmitz, J.

    2001-06-01

    The optoelectronic properties of short-period InAs/(GaIn)Sb superlattices (SLs) grown by molecular beam epitaxy on GaSb substrates are discussed. We report on the optimization of the SL materials properties with special emphasis on the use for infrared detection devices. The materials quality is evaluated by using high resolution x-ray diffraction, atomic force microscopy, and photoluminescence spectroscopy. In- plane magneto-transport investigations were performed applying mobility spectrum analysis. The SL diodes were analyzed performing standard electro-optical measurements. The observation of resonances in the I-V curves in the regime of Zener-tunneling due to Wannier-Stark localization opens a new tool for the electrical investigation of photodiodes with low band gap energy. The status of the processing technology is reported demonstrating the feasibility for the fabrication of 256 X 256 focal plane arrays operating in the 8-to-12 micrometers atmospheric window. In addition, results are given for mid-infrared SL-diodes, grown with lattice matched AlGaAsSb barriers instead in the binary InAs/GaSb SL system.

  14. An investigation of signal performance enhancements achieved through innovative pixel design across several generations of indirect detection, active matrix, flat-panel arrays

    SciTech Connect

    Antonuk, Larry E.; Zhao Qihua; El-Mohri, Youcef; Du Hong; Wang Yi; Street, Robert A.; Ho, Jackson; Weisfield, Richard; Yao, William

    2009-07-15

    Active matrix flat-panel imager (AMFPI) technology is being employed for an increasing variety of imaging applications. An important element in the adoption of this technology has been significant ongoing improvements in optical signal collection achieved through innovations in indirect detection array pixel design. Such improvements have a particularly beneficial effect on performance in applications involving low exposures and/or high spatial frequencies, where detective quantum efficiency is strongly reduced due to the relatively high level of additive electronic noise compared to signal levels of AMFPI devices. In this article, an examination of various signal properties, as determined through measurements and calculations related to novel array designs, is reported in the context of the evolution of AMFPI pixel design. For these studies, dark, optical, and radiation signal measurements were performed on prototype imagers incorporating a variety of increasingly sophisticated array designs, with pixel pitches ranging from 75 to 127 {mu}m. For each design, detailed measurements of fundamental pixel-level properties conducted under radiographic and fluoroscopic operating conditions are reported and the results are compared. A series of 127 {mu}m pitch arrays employing discrete photodiodes culminated in a novel design providing an optical fill factor of {approx}80% (thereby assuring improved x-ray sensitivity), and demonstrating low dark current, very low charge trapping and charge release, and a large range of linear signal response. In two of the designs having 75 and 90 {mu}m pitches, a novel continuous photodiode structure was found to provide fill factors that approach the theoretical maximum of 100%. Both sets of novel designs achieved large fill factors by employing architectures in which some, or all of the photodiode structure was elevated above the plane of the pixel addressing transistor. Generally, enhancement of the fill factor in either discrete or

  15. An investigation of signal performance enhancements achieved through innovative pixel design across several generations of indirect detection, active matrix, flat-panel arrays

    PubMed Central

    Antonuk, Larry E.; Zhao, Qihua; El-Mohri, Youcef; Du, Hong; Wang, Yi; Street, Robert A.; Ho, Jackson; Weisfield, Richard; Yao, William

    2009-01-01

    Active matrix flat-panel imager (AMFPI) technology is being employed for an increasing variety of imaging applications. An important element in the adoption of this technology has been significant ongoing improvements in optical signal collection achieved through innovations in indirect detection array pixel design. Such improvements have a particularly beneficial effect on performance in applications involving low exposures and∕or high spatial frequencies, where detective quantum efficiency is strongly reduced due to the relatively high level of additive electronic noise compared to signal levels of AMFPI devices. In this article, an examination of various signal properties, as determined through measurements and calculations related to novel array designs, is reported in the context of the evolution of AMFPI pixel design. For these studies, dark, optical, and radiation signal measurements were performed on prototype imagers incorporating a variety of increasingly sophisticated array designs, with pixel pitches ranging from 75 to 127 μm. For each design, detailed measurements of fundamental pixel-level properties conducted under radiographic and fluoroscopic operating conditions are reported and the results are compared. A series of 127 μm pitch arrays employing discrete photodiodes culminated in a novel design providing an optical fill factor of ∼80% (thereby assuring improved x-ray sensitivity), and demonstrating low dark current, very low charge trapping and charge release, and a large range of linear signal response. In two of the designs having 75 and 90 μm pitches, a novel continuous photodiode structure was found to provide fill factors that approach the theoretical maximum of 100%. Both sets of novel designs achieved large fill factors by employing architectures in which some, or all of the photodiode structure was elevated above the plane of the pixel addressing transistor. Generally, enhancement of the fill factor in either discrete or continuous

  16. MBE growth of HgCdTe avalanche photodiode structures for low-noise 1.55 μm photodetection

    NASA Astrophysics Data System (ADS)

    de Lyon, T. J.; Baumgratz, B.; Chapman, G.; Gordon, E.; Hunter, A. T.; Jack, M.; Jensen, J. E.; Johnson, W.; Johs, B.; Kosai, K.; Larsen, W.; Olson, G. L.; Sen, M.; Walker, B.; Wu, O. K.

    1999-05-01

    Molecular-beam epitaxy (MBE) has been utilized to fabricate HgCdTe heterostructure separate absorption and multiplication avalanche photodiodes (SAM-APD) sensitive to infrared radiation in the 1.1-1.6 μm spectral range, as an alternative technology to existing III-V APD detectors. Device structures were grown on CdZnTe(211)B substrates using CdTe, Te, and Hg sources with in situ In and As doping. The composition of the HgCdTe alloy layers was adjusted to achieve both efficient absorption of IR radiation in the 1.1-1.6 μm spectral range and low excess-noise avalanche multiplication. The Hg 1- xCd xTe alloy composition in the gain region of the device, x=0.73, was selected to achieve equality between the bandgap energy and spin-orbit splitting to resonantly enhance the impact ionization of holes in the split-off valence band. The appropriate value of this alloy composition was determined from analysis of the 300 K bandgap and spin-orbit splitting energies of a set of calibration layers, using a combination of IR transmission and spectroscopic ellipsometry measurements. MBE-grown APD epitaxial wafers were processed into passivated mesa-type discrete device structures and diode mini-arrays using conventional HgCdTe process technology. Device spectral response, dark current density, and avalanche gain measurements were performed on the processed wafers. Avalanche gains in the range of 30-40 at reverse bias of 85-90 V and array-median dark current density below 2×10 -4 A/cm 2 at 40 V reverse bias have been demonstrated.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. The EAS-1000 array

    SciTech Connect

    Khristiansen, G.B.; Fomin, IU.A.; Chasnikov, I.IA.; Ivanenko, V.M.; Efimov, N.N. )

    1989-01-01

    The requirements for a newly constructed EAS array are summarized, and the EAS-1000 array now under construction is described. The array is depicted, and its accuracy in finding EAS parameters is shown. The expected statistics in observing EAS of different energies are presented for the most important scientific problems the array is supposed to solve.

  4. Collection of photogenerated charge carriers in small-pitched infrared photovoltaic focal plane arrays

    NASA Astrophysics Data System (ADS)

    Chekanova, Galina V.; Drugova, Albina A.; Kholodnov, Viacheslav; Nikitin, Mikhail S.

    2010-10-01

    Technology of infrared (IR) photovoltaic (PV) focal plane arrays (FPA) covering spectral range from 1.6 to 14 μm gradually moves from simple quasi-matrix (linear) arrays like as 4×288 pixels to large format high definition arrays 1280×1024 pixels and more. Major infrared detector materials for PV technology are InSb and its alloys and ternary alloys Hg1-xCdxTe. Progress in IR PV technology was provided in last decade by serious improvement in material growing techniques. Increasing of PV array format is related always to decreasing of pixel size and spacing between neighbor pixels to minimal size reasonable from point of view of infrared physics. So pitch is small (15-25 μm) in large format arrays. Ambipolar diffusion length of photogenerated charge carriers can exceed pitch many times in high quality absorption layers of PV arrays. It means that each pixel can collect excess charge carriers generated far from n+-p junction border. Optimization of resolution, filling factor and cross-talking level of small-pitched PV FPA requires comprehensive estimation of photodiode's (PD) pixel performance depending on pixel and array design, material properties and operating conditions. Objective of the present work was to develop general approach to estimate collection of photogenerated charge carriers in small-pitched arrays.

  5. Solar array drive system

    NASA Technical Reports Server (NTRS)

    Berkopec, F. D.; Sturman, J. C.; Stanhouse, R. W.

    1976-01-01

    A solar array drive system consisting of a solar array drive mechanism and the corresponding solar array drive electronics is being developed. The principal feature of the solar array drive mechanism is its bidirectional capability which enables its use in mechanical redundancy. The solar array drive system is of a widely applicable design. This configuration will be tested to determine its acceptability for generic mission sets. Foremost of the testing to be performed is the testing for extended duration.

  6. Integrated infrared array technology

    NASA Technical Reports Server (NTRS)

    Goebel, J. H.; Mccreight, C. R.

    1986-01-01

    An overview of integrated infrared (IR) array technology is presented. Although the array pixel formats are smaller, and the readout noise of IR arrays is larger, than the corresponding values achieved with optical charge-coupled-device silicon technology, substantial progress is being made in IR technology. Both existing IR arrays and those being developed are described. Examples of astronomical images are given which illustrate the potential of integrated IR arrays for scientific investigations.

  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. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Low bandgap mid-infrared thermophotovoltaic arrays based on InAs

    NASA Astrophysics Data System (ADS)

    Krier, A.; Yin, M.; Marshall, A. R. J.; Kesaria, M.; Krier, S. E.; McDougall, S.; Meredith, W.; Johnson, A. D.; Inskip, J.; Scholes, A.

    2015-11-01

    We demonstrate the first low bandgap thermophotovoltaic (TPV) arrays capable of operating with heat sources at temperatures as low as 345 °C, which is the lowest ever reported. The individual array elements are based on narrow band gap InAs/InAs0.61Sb0.13P0.26 photodiode structures. External power conversion efficiency was measured to be ∼3% from a single element at room temperature, using a black body at 950 °C. Both 25-element and 65-element arrays were fabricated and exhibited a TPV response at different source temperatures in the range 345-950 °C suitable for electricity generation from waste heat and other applications.

  7. 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.

  8. Optical cross-talk effect in a semiconductor photon-counting detector array

    NASA Astrophysics Data System (ADS)

    Prochazka, Ivan; Hamal, Karel; Kral, Lukas; Blazej, Josef

    2005-09-01

    Solid state single photon detectors are getting more and more attention in various areas of applied physics: optical sensors, communication, quantum key distribution, optical ranging and Lidar, time resolved spectroscopy, opaque media imaging and ballistic photon identification. 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 InGaAs/InGaAsP at the Czech Technical University in Prague during the last 20 years. They have been tailored for numerous applications. Recently, there is a strong demand for the photon counting detector in a form of an array; even small arrays 10x1 or 3x3 are of great importance for users. Although the photon counting array can be manufactured, there exists a serious limitation for its performance: the optical cross-talk between individual detecting cells. This cross-talk is caused by the optical emission of the avalanche photon counting structure which accompanies the photon detection process. We have studied in detail the optical emission of the avalanche photon counting structure in the silicon shallow junction type photodiode. The timing properties, radiation pattern and spectral distribution of the emitted light have been measured for various detection structures and their different operating conditions. The ultimate limit for the cross-talk has been determined and the methods for its limitation have been proposed.

  9. Electronic component design and testing for multielement IR arrays with CCD readout devices

    NASA Astrophysics Data System (ADS)

    Darchuk, Sergey D.; Derkach, Yurii P.; Kononenko, Yu. G.; Reva, Vladimir P.; Sizov, Fiodor F.; Tetyorkin, Vladimir V.

    1997-08-01

    P-channel silicon direct injection read-out devices with p- type buried channel CD multiplexers which consist of input circuits, shift register and output circuits were designed, fabricated and tested. Read-out devices were designed for using with IR p-n-photodiode linear arrays. The dynamical range of p-type read-out devices was estimated to be of the order of 60 dB at T equals 80 K. The two-phase p-channel CCD shift register was designed with 5 MHz clock frequency operation. Transfer efficiency without fat zero was 0.99985 at 1.0 MHz.

  10. A 4 π charged-particle detector array for light-ion-induced nuclear fragmentation studies

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, K.; Alexander, A.; Bracken, D. S.; Brzychczyk, J.; Dorsett, J.; Ensman, R.; Renshaw Foxford, E.; Hamilton, T.; Komisarcik, K.; McDonald, K. N.; Morley, K. B.; Poehlman, J.; Powell, C.; Viola, V. E.; Yoder, N. R.; Ottarson, J.; Madden, N.

    1994-12-01

    Operating characteristics of the Indiana Silicon Sphere 4 π detector array are outlined. The detector geometry is spherical, with 90 telescopes in the forward hemisphere and 72 at backward angles, covering a total solid angle of 74% of 4π. Each telescope consists of a simple gas-ion chamber, operated with C3F8 gas, followed by a 0.5 mm thick ion-implanted silicon detector and a 28 mm CsI(Tl) crystal, readout by a photodiode. Custom-built bias supplies and NIM preamp/shaper modules were used in conjunction with commercial CFD, TDC and ADC CAMAC units.

  11. 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

  12. 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.

  13. Development of the HgCdTe Avalanche Photodiode Detectors and the Improvement in the CO2 Lidar Performance for the ASCENDS Mission

    NASA Astrophysics Data System (ADS)

    Sun, X.; Abshire, J. B.; Chen, J. R.; Ramanathan, A. K.; Mao, J.

    2015-12-01

    NASA Goddard Space Flight Center (GSFC) is developing the CO2 lidar as a candidate for the NASA's planned ASCENDS mission under the support of Earth Science Technology Office (ESTO) IIP and ATI-QRS programs. A new type of HgCdTe avalanche photodiode (APD) detector has been developed by the DRS Technologies under the IIP program. The new detectors achieved >70% quantum efficiency, including the effect of the fill factor, over the spectral range from 0.4 to 4.3 μm, which significantly improves the receiver performance of our CO2 lidar and enabled other remote sending measurements. The HgCdTe APD arrays have 80 μm square pixels in a 4x4 array along with a bank of 16 preamplifiers on the same chip carrier. Test results at both DRS and GSFC showed the HgCdTe APD array has achieved, an APD gain of 500-1000, 8-10 MHz electrical bandwidth, and an average noise equivalent power (NEP) of <0.5 fW/Hz1/2. It has demonstrated at least a 3 orders of magnitude dynamic range at a fixed APD gain setting. The gains of the APD and the preamplifier can also be adjusted to further extend the receiver dynamic range. During summer 2014 we successfully demonstrated airborne lidar measurements of column CO2 using one of these detectors. The Aerospace Corporation is currently building a 3U CubeSat with one of these detectors in a small closed-cycle cryocooler as the primary payload under the ESTO In-space Validation of Earth Science Technology (InVEST) program. The CubeSat is scheduled to be launched in late 2016 and will fly in a low Earth orbit and monitor the performance for at least a year. We have also updated the performance analysis of a space-based version of our CO2 lidar with the new HgCdTe APD detector. For the retrievals, a least-square-error method is used to fit the measured transmittances to a predetermined line shape function using 8 to 16 sampling wavelengths. The error in the derived total optical depth and the CO2 mixing ratio are estimated via the standard error

  14. Twenty-channel bolometer array for studying impurity radiation and transport in the TCS field-reversed configuration

    NASA Astrophysics Data System (ADS)

    Kostora, M. R.; Hsu, S. C.; Wurden, G. A.

    2006-10-01

    A bolometer array diagnostic has been developed for the University of Washington Translation, Confinement, and Sustainment (TCS) field-reversed configuration (FRC) experiment in order to measure radially resolved total radiated power per unit length of the FRC. This will provide radiation energy loss information, useful in power balance and impurity studies. The 20-element photodiode bolometer will be mounted at the midplane of the TCS cylindrical vacuum chamber to view the rotating magnetic field (RMF) generated FRC plasma. Key features of this new bolometer array are (1) extensive electrical shielding against the RMF, (2) robust electrical isolation, (3) trans-impedance amplifiers using a microcoax interface at the array and a fiber optic interface to the screen room, and (4) a custom glass-on-metal socket for the 20-element photodiode chip to ensure high vacuum compatibility. The bolometer array can be retracted behind a gate valve using a stepper motor to protect it during vacuum chamber bakeout. The slit assembly housing is interchangeable to provide flexibility for the viewing sightlines.

  15. Axiom turkey genotyping array

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Axiom®Turkey Genotyping Array interrogates 643,845 probesets on the array, covering 643,845 SNPs. The array development was led by Dr. Julie Long of the USDA-ARS Beltsville Agricultural Research Center under a public-private partnership with Hendrix Genetics, Aviagen, and Affymetrix. The Turk...

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Implementation of Strategies to Improve the Reliability of III-Nitride Photodetectors towards the Realization of Visible and Solar-Blind Imaging Arrays

    NASA Astrophysics Data System (ADS)

    Bulmer, John J.

    isolates conductive pathways in III-Nitrides using an electrochemical etch and novel foam passivation technique. Establishing improved photodiode performance and device reliability, 4x4 and 8x8 arrays of GaN p-i-n photodiodes were demonstrated and integrated with external circuitry to generate image patterns using 360nm illumination. This work represents significant progress towards the realization of reliable III-Nitride UV detectors arrays and future directions are proposed in order to demonstrate large-scale arrays for high-resolution ultraviolet imaging.

  4. 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.

  5. A 64 single photon avalanche diode array in 0.18 µm CMOS standard technology with versatile quenching circuit for quick prototyping

    NASA Astrophysics Data System (ADS)

    Uhring, Wilfried; Le Normand, Jean-Pierre; Zint, Virginie; Dumas, Norbert; Dadouche, Foudil; Malasse, Imane; Scholz, Jeremy

    2012-04-01

    Several works have demonstrated the successfully integration of Single-photon avalanche photodiodes (SPADs) operating in Geiger mode in a standard CMOS circuit for the last 10 years. These devices offer an exceptional temporal resolution as well as a very good optical sensitivity. Nevertheless, it is difficult to predict the expected performances of such a device. Indeed, for a similar structure of SPAD, some parameter values can differ by two orders of magnitude from a technology to another. We proposed here a procedure to identify in just one or two runs the optimal structure of SPAD available for a given technology. A circuit with an array of 64 SPAD has been realized in the Tower-Jazz 0.18 μm CMOS image sensor process. It encompasses an array of 8 different structures of SPAD reproduced in 8 diameters in the range from 5 μm up to 40 μm. According to the SPAD structures, efficient shallow trench insulator and/or P-Well guard ring are used for preventing edge breakdown. Low dark count rate of about 100 Hz are expected thanks to the use of buried n-well layer and a high resistivity substrate. Each photodiode is embedded in a pixel which includes a versatile quenching circuitry and an analog output of its cathode voltage. The quenching system is configurable in four operation modes; the SPAD is disabled, the quenching is completely passive, the reset of the photodiode is active and the quenching is fully active. The architecture of the array makes possible the characterization of every single photodiode individually. The parameters to be measured for a SPAD are the breakdown avalanche voltage, the dark count rate, the dead time, the timing jitter, the photon detection probability and the after-pulsing rate.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. High-speed on-chip windowed centroiding using photodiode-based CMOS imager

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata (Inventor); Sun, Chao (Inventor); Yang, Guang (Inventor); Cunningham, Thomas J. (Inventor); Hancock, Bruce (Inventor)

    2003-01-01

    A centroid computation system is disclosed. The system has an imager array, a switching network, computation elements, and a divider circuit. The imager array has columns and rows of pixels. The switching network is adapted to receive pixel signals from the image array. The plurality of computation elements operates to compute inner products for at least x and y centroids. The plurality of computation elements has only passive elements to provide inner products of pixel signals the switching network. The divider circuit is adapted to receive the inner products and compute the x and y centroids.

  12. High-speed on-chip windowed centroiding using photodiode-based CMOS imager

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata (Inventor); Sun, Chao (Inventor); Yang, Guang (Inventor); Cunningham, Thomas J. (Inventor); Hancock, Bruce (Inventor)

    2004-01-01

    A centroid computation system is disclosed. The system has an imager array, a switching network, computation elements, and a divider circuit. The imager array has columns and rows of pixels. The switching network is adapted to receive pixel signals from the image array. The plurality of computation elements operates to compute inner products for at least x and y centroids. The plurality of computation elements has only passive elements to provide inner products of pixel signals the switching network. The divider circuit is adapted to receive the inner products and compute the x and y centroids.

  13. Thermophotovoltaic Array Optimization

    SciTech Connect

    SBurger; E Brown; K Rahner; L Danielson; J Openlander; J Vell; D Siganporia

    2004-07-29

    A systematic approach to thermophotovoltaic (TPV) array design and fabrication was used to optimize the performance of a 192-cell TPV array. The systematic approach began with cell selection criteria that ranked cells and then matched cell characteristics to maximize power output. Following cell selection, optimization continued with an array packaging design and fabrication techniques that introduced negligible electrical interconnect resistance and minimal parasitic losses while maintaining original cell electrical performance. This paper describes the cell selection and packaging aspects of array optimization as applied to fabrication of a 192-cell array.

  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. Solar-blind AlGaN 256×256 p-i-n detectors and focal plane arrays

    NASA Astrophysics Data System (ADS)

    Reine, M. B.; Hairston, A.; Lamarre, P.; Wong, K. K.; Tobin, S. P.; Sood, A. K.; Cooke, C.; Pophristic, M.; Guo, S.; Peres, B.; Singh, R.; Eddy, C. R. _Jr., Jr.; Chowdhury, U.; Wong, M. M.; Dupuis, R. D.; Li, T.; DenBaars, S. P.

    2006-02-01

    This paper reports the development of aluminum-gallium nitride (AlGaN or Al xGa 1-xN) photodiode technology for high-operability 256×256 hybrid Focal Plane Arrays (FPAs) for solar-blind ultraviolet (UV) detection in the 260-280 nm spectral region. These hybrid UV FPAs consist of a 256×256 back-illuminated AlGaN p-i-n photodiode array, operating at zero bias voltage, bump-mounted to a matching 256×256 silicon CMOS readout integrated circuit (ROIC) chip. The unit cell size is 30×30 μm2. The photodiode arrays were fabricated from multilayer AlGaN films grown by MOCVD on 2" dia. UV-transparent sapphire substrates. Improvements in AlGaN material growth and device design enabled high quantum efficiency and extremely low leakage current to be achieved in high-operability 256×256 p-i-n photodiode arrays with cuton and cutoff wavelengths of 260 and 280 nm, placing the response in the solar-blind wavelength region (less than about 280 nm) where solar radiation is heavily absorbed by the ozone layer. External quantum efficiencies (at V=0, 270 nm, no antireflection coating) as high as 58% were measured in back-illuminated devices. A number of 256×256 FPAs, with the AlGaN arrays fabricated from films grown at three different facilities, achieved response operabilities as high as 99.8%, response nonuniformities (σ/μ) as low as 2.5%, and zero-bias resistance median values as high as 1×10 16 ohm, corresponding to R0A products of 7×10 10 ohm-cm2. Noise Equivalent Irradiance (NEI) data were measured on these FPAs. Median NEI values at 1 Hz are 250-500 photons/pixel-s, with best-element values as low as 90 photons/pixel-s at 1 Hz.

  18. 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.

  19. 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.

  20. 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.