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Sample records for area hybrid photodiodes

  1. Hybrid Avalanche Photodiode Array Imaging

    NASA Astrophysics Data System (ADS)

    Aihara, Hiroaki

    A hybrid avalanche photodiode (APD) array is a vacuum tube containing a photocathode and an array of avalanche photodiodes. It is a hybrid device that combines a traditional phototube technology and an advanced semiconductor technology. A photon produces a photoelectron with quantum efficiency at the photocathode. Unlike a phototube with dynodes, multiplication of the photoelectron is provided by a bombardment of the accelerated photoelectron into the avalanche photodiode resulting in a number of electron-hole pairs and a subsequent avalanche multiplication of the secondary electrons at the pn junction of the reverse-biased diode. The resulting total gain ranging from 104 to 105 is large enough to retain a single-photon sensitivity by using low-noise amplifiers. Segmentation of the pn junction of the diode provides the position information of an incident photoelectron and enables imaging of an incident photon. We report the recent progress on R&D of a single-pixel large format hybrid APD and a multipixel hybrid APD array. A hybrid avalanche photodiode (APD) array is a vacuum tube containing a photocathode and an array of avalanche photodiodes. It is a hybrid device that combines a traditional phototube technology and an advanced semiconductor technology. A photon produces a photoelectron with quantum efficiency at the photocathode. Unlike a phototube with dynodes, multiplication of the photoelectron is provided by a bombardment of the accelerated photoelectron into the avalanche photodiode resulting in a number of electron-hole pairs and a subsequent avalanche multiplication of the secondary electrons at the pn junction of the reverse-biased diode. The resulting total gain ranging from 104 to 105 is large enough to retain a single-photon sensitivity by using low-noise amplifiers. Segmentation of the pn junction of the diode provides the position information of an incident photoelectron and enables imaging of an incident photon. We report the recent progress on R

  2. 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.

  3. Test of the DEP hybrid photodiode in 5 Tesla Magnet

    SciTech Connect

    Green, D; Freeman, J.; Ronzhin, A.; Cushman, R.; Heering, A.

    1997-10-01

    The CMS detector is designed so that the tile/fiber hadronic calorimeter (HCAL) is immersed in a 4 Tesla magnetic field. The Hybrid Photodiode (HPD) will be used as the photodetector. Below we present the experiment data which we obtained on the HPD behavior in a magnetic field.

  4. Chopped Radiation Measurements With Large Area Si Photodiodes

    PubMed Central

    Eppeldauer, George

    1998-01-01

    Frequency dependent response characteristics of photocurrent meters using large area, radiometric quality Si photodiodes have been analyzed. The current responsivity, the voltage noise and drift amplification, and the gain and bandwidth of the photocurrent-measuring analog control loop were calculated. The photodiodes were selected for high shunt resistance. The effect of the photodiode junction capacitance on the response characteristics was also analyzed. As a result of photocurrent gain dependent frequency compensations, the noise boosting effect was minimized at the output of the current meter. The loop gain and bandwidth were maximized. High-accuracy photocurrent measurements can be achieved using the described procedures for both dc and modulated optical radiation. PMID:28009366

  5. 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

  6. Amplifiers dedicated for large area SiC photodiodes

    NASA Astrophysics Data System (ADS)

    Doroz, P.; Duk, M.; Korwin-Pawlowski, M. L.; Borecki, M.

    2016-09-01

    Large area SiC photodiodes find applications in optoelectronic sensors working at special conditions. These conditions include detection of UV radiation in harsh environment. Moreover, the mentioned sensors have to be selective and resistant to unwanted signals. For this purpose, the modulation of light at source unit and the rejection of constant current and low frequency component of signal at detector unit are used. The popular frequency used for modulation in such sensor is 1kHz. The large area photodiodes are characterized by a large capacitance and low shunt resistance that varies with polarization of the photodiode and can significantly modify the conditions of signal pre-amplification. In this paper two pre-amplifiers topology are analyzed: the transimpedance amplifier and the non-inverting voltage to voltage amplifier with negative feedback. The feedback loops of both pre-amplifiers are equipped with elements used for initial constant current and low frequency signals rejections. Both circuits are analyzed and compared using simulation and experimental approaches.

  7. 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)

  8. Recent advances in very large area avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Squillante, Michael R.; Christian, James; Entine, Gerald; Farrell, Richard; Karger, Arieh M.; McClish, Mickel; Myers, Richard; Shah, Kanai S.; Taylor, David; Vanderpuye, Kofi; Waer, Peter; Woodring, Mitchell

    2003-09-01

    The Avalanche Photodiode (APD) is a unique device that combines the advantages of solid state photodetectors with those of high gain devices such as photomultiplier tubes (PMTs). APDs have internal gain that provides a high signal-to-noise ratio. APDs have high quantum efficiency, are fast, compact, and rugged. These properties make them suitable detectors for important applications such as LADAR, detection and identification toxic chemicals and bio-warfare agents, LIDAR fluorescence detection, stand-off laser induced breakdown spectroscopy (LIBS), and nuclear detectors and imagers. Recently there have been significant technical breakthroughs in fabricating very large APDs, APD arrays, and position sensitive APD arrays (PSAPD). Signal gain of over 10,000 has been achieved, single element APDs have been fabricated with active area greater than 40 cm2, monolithic pixelated arrays with up to 28 x 28 elements have been fabricated, and position sensitive APDs have been developed and tested. Additionally, significant progress has been made in improving the fabrication process to provide better uniformity and high yield, permitting cost effective manufacturing of APDs for reduced cost.

  9. High Photocurrent in Gated Graphene–Silicon Hybrid Photodiodes

    PubMed Central

    2017-01-01

    Graphene/silicon (G/Si) heterojunction based devices have been demonstrated as high responsivity photodetectors that are potentially compatible with semiconductor technology. Such G/Si Schottky junction diodes are typically in parallel with gated G/silicon dioxide (SiO2)/Si areas, where the graphene is contacted. Here, we utilize scanning photocurrent measurements to investigate the spatial distribution and explain the physical origin of photocurrent generation in these devices. We observe distinctly higher photocurrents underneath the isolating region of graphene on SiO2 adjacent to the Schottky junction of G/Si. A certain threshold voltage (VT) is required before this can be observed, and its origins are similar to that of the threshold voltage in metal oxide semiconductor field effect transistors. A physical model serves to explain the large photocurrents underneath SiO2 by the formation of an inversion layer in Si. Our findings contribute to a basic understanding of graphene/semiconductor hybrid devices which, in turn, can help in designing efficient optoelectronic devices and systems based on such 2D/3D heterojunctions. PMID:28781983

  10. 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).

  11. Monolithic and hybrid near infrared detection and imaging based on poly-Ge photodiode arrays

    NASA Astrophysics Data System (ADS)

    Masini, G.; Colace, L.; Petulla, F.; Assanto, G.; Cencelli, V.; DeNotaristefani, F.

    2005-02-01

    In recent years, several Ge-on-Si technologies for the fabrication of near infrared photodetectors on Si substrates were proposed. In particular, using a low temperature (300 °C) technique, we have demonstrated poly-Ge_on_Si detectors with high speed and good NIR responsivity. The low process temperature allows the monolithic integration of the detectors as a final step in the fabrication of Si CMOS integrated circuits. After an introduction on poly-Ge, we describe a novel integrated chip (NIRCAM-1) designed as a readout/control circuit for arrays of 64 (32) poly-Ge_on_Si photodetectors. The photodiodes, monolithically integrated (wire-bonded with a hybrid approach) on the IC, generate a photocurrent which is then ADC converted after subtraction of the dark component, thus allowing a convenient digital readout of the array. The extensive optoelectronic characterization of the IC is presented.

  12. Recent advances with mercuric iodide x-ray detectors and large-area silicon avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Dabrowski, Andrzej J.; Iwanczyk, Jan S.; Wang, Yuzhong J.; Madden, Michael C.; Szawlowski, Marek

    1993-10-01

    The paper presents advances in two sensor technologies: (1) Mercuric Iodide (HgI2) X-ray Detector Technology and, (2) Large Area Silicon Avalanche Photodiode (APD) Technology, which after years of development have recently produced commercially viable devices. Large Area Silicon Avalanche Photodiodes, which are solid-state light sensitive devices with internal amplification, combine the convenience, ruggedness and low power consumption of traditional semiconductor p-n and p-i-n photodiodes with the high light sensitivity and large photosensitive area approaching the active areas of traditional vacuum photomultiplier tubes. Device approaching 1-inch diameter with internal gain of up to 1000, have been developed by utilizing a beveled edge structure. By combining APD's with scintillation crystals, resolution of 6% (FWHM) was obtained for 662 keV energy line of 137Cs using a CsI(Tl) scintillator, and 7% (FWHM) was obtained using a NaI(Tl) scintillator. Resolution of 14% (FWHM) at room temperature and 11% (FWHM) at 0 degree(s)C have been obtained for APD's coupled to BGO scintillators. Rise times of 3 ns were measured by applying an impulse signal input, to a 200 mm2 device.

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

    NASA Astrophysics Data System (ADS)

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

    1992-03-01

    Avalanche photodiodes (APDs) 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 < 1 mm2. Recent advances in fabrication technology have, however, resulted in relatively low-noise devices of up to 1 in. in diameter. We have recently evaluated the performance as scintillation spectroscopy detectors of two commercial large-area avalanche photodiodes. These APDs exhibit exceptional performance: at 662 keV a 1-in. diameter device coupled to a CsI(Tl) scintillator and operating at room temperature yielded 6.9% resolution and a 1-cm device coupled to CsI(Tl) and cooled to 260 K gave 4.4% resolution, which is believed to be the best resolution ever recorded for a scintillation spectrometer.

  14. 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.

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

    PubMed

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

    2014-01-07

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  18. Highly sensitive visible-blind extreme ultraviolet Ni/4H-SiC Schottky photodiodes with large detection area.

    PubMed

    Hu, Jun; Xin, Xiaobin; Zhao, Jian H; Yan, Feng; Guan, Bing; Seely, John; Kjornrattanawanich, Benjawan

    2006-06-01

    Ni/4H-SiC Schottky photodiodes of 5 mm x 5 mm area have been fabricated and characterized. The photodiodes show less than 0.1 pA dark current at -4 V and an ideality factor of 1.06. A quantum efficiency (QE) between 3 and 400 nm has been calibrated and compared with Si photodiodes optimized for extreme ultraviolet (EUV) detection. In the EUV region, the QE of SiC detectors increases from 0.14 electrons/photon at 120 nm to 30 electrons/photon at 3 nm. The mean energy of electron-hole pair generation of 4H-SiC estimated from the spectral QE is found to be 7.9 eV.

  19. Planar avalanche photodiodes with edge breakdown suppression using a novel selective area growth based process

    NASA Astrophysics Data System (ADS)

    Pitts, O. J.; Hisko, M.; Benyon, W.; Bonneville, G.; Storey, C.; SpringThorpe, A. J.

    2017-07-01

    We propose and demonstrate a novel process to fabricate planar avalanche photodiodes using selective area growth (SAG) followed by a single Zn diffusion through the SAG material using the same dielectric mask. The tapered surface profile of the SAG epitaxy due to the enhancement of the growth rate in the vicinity of the mask edge modifies the diffusion profile, resulting in a gradual reduction of the diffusion depth towards the outer edge of the active area. The associated reduction of the electric field counteracts the edge curvature effect sufficiently to suppress edge breakdown. For undoped InP SAG epitaxy, small areas of higher electric field occur where the mask edge is along the [1 0 0] or [0 1 0] directions, associated with the formation of enhanced ridges in the SAG material in these locations. Similar ridges are observed for Si-doped InP and InP/InGaAs/InP SAG structures, but the enhancement of the electric field in these locations is significantly lower.

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

    PubMed

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

    2012-05-01

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

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

    SciTech Connect

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

    2012-05-15

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

  2. 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.

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

    PubMed

    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 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-xray/ extreme-UV applications involving synchrotron radiation.

  4. 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).

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. 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.

  8. 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

  9. A hybrid organic semiconductor/silicon photodiode for efficient ultraviolet photodetection.

    PubMed

    Levell, J W; Giardini, M E; Samuel, I D W

    2010-02-15

    A method employing conjugated polymer thin film blends is shown to provide a simple and convenient way of greatly enhancing the ultraviolet response of silicon photodetectors. Hybrid organic semiconductor/silicon photodetectors are demonstrated using fluorene copolymers and give a quantum efficiency of 60% at 200 nm. The quantum efficiency is greater than 34% over the entire 200-620 nm range. These devices show promise for use in high sensitivity, low cost UV-visible photodetection and imaging applications.

  10. 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

  11. Photodiodes based in La0.7Sr0.3MnO3/single layer MoS2 hybrid vertical heterostructures

    NASA Astrophysics Data System (ADS)

    Niu, Yue; Frisenda, Riccardo; Svatek, Simon A.; Orfila, Gloria; Gallego, Fernando; Gant, Patricia; Agraït, Nicolás; Leon, Carlos; Rivera-Calzada, Alberto; Pérez De Lara, David; Santamaria, Jacobo; Castellanos-Gomez, Andres

    2017-09-01

    The fabrication of artificial materials by stacking of individual two-dimensional (2D) materials is amongst one of the most promising research avenues in the field of 2D materials. Moreover, this strategy to fabricate new man-made materials can be further extended by fabricating hybrid stacks between 2D materials and other functional materials with different dimensionality making the potential number of combinations almost infinite. Among all these possible combinations, mixing 2D materials with transition metal oxides can result especially useful because of the large amount of interesting physical phenomena displayed separately by these two material families. We present a hybrid device based on the stacking of a single layer MoS2 onto a lanthanum strontium manganite (La0.7Sr0.3MnO3) thin film, creating an atomically thin device. It shows a rectifying electrical transport with a ratio of 103, and a photovoltaic effect with V oc up to 0.4 V. The photodiode behaviour arises as a consequence of the different doping character of these two materials. This result paves the way towards combining the efforts of these two large materials science communities.

  12. CLASSICAL AREAS OF PHENOMENOLOGY: Design of novel three port optical gates scheme for the integration of large optical cavity electroabsorption modulators and evanescently-coupled photodiodes

    NASA Astrophysics Data System (ADS)

    Liao, Zai-Yi; Yang, Hua; Wang, Wei

    2008-07-01

    This paper presents a novel scheme to monolithically integrate an evanescently-coupled uni-travelling carrier photodiode with a planar short multimode waveguide structure and a large optical cavity electroabsorption modulator based on a multimode waveguide structure. By simulation, both electroabsorption modulator and photodiode show excellent optical performances. The device can be fabricated with conventional photolithography, reactive ion etching, and chemical wet etching.

  13. Collaborations among Diverse Support Areas for Hybrid Success

    ERIC Educational Resources Information Center

    Haggar, Faye; Kelley, Bruce; Chen, Weichao

    2017-01-01

    Successful implementation of hybrid courses typically demands collaboration among diverse support areas on campus. This article examines these collaborations through the lens of Badrul Khan's theory of managing blended learning support. Also discussed is the central role that faculty developers can play in connecting these support areas to ensure…

  14. High-speed, large-area, p-i-n InGaAs photodiode linear array at 2-micron wavelength

    NASA Astrophysics Data System (ADS)

    Joshi, Abhay; Datta, Shubhashish

    2012-06-01

    We present 16-element and 32-element lattice-mismatched InGaAs photodiode arrays having a cut-off wavelength of ~2.2 um. Each 100 um × 200 um large pixel of the 32-element array has a capacitance of 2.5 pF at 5 V reverse bias, thereby allowing a RC-limited bandwidth of ~1.3 GHz. At room temperature, each pixel demonstrates a dark current of 25 uA at 5 V reverse bias. Corresponding results for the 16-element array having 200 um × 200 um pixels are also reported. Cooling the photodiode array to 150K is expected to reduce its dark current to < 50 nA per pixel at 5 V reverse bias. Additionally, measurement results of 2-micron single photodiodes having 16 GHz bandwidth and corresponding PIN-TIA photoreceiver having 6 GHz bandwidth are also reported.

  15. Lateral drift-field photodiode for low noise, high-speed, large photoactive-area CMOS imaging applications

    NASA Astrophysics Data System (ADS)

    Durini, Daniel; Spickermann, Andreas; Mahdi, Rana; Brockherde, Werner; Vogt, Holger; Grabmaier, Anton; Hosticka, Bedrich J.

    2010-12-01

    In this work a theoretical concept and simulations are presented for a novel lateral drift-field photodetector pixel to be fabricated in a 0.35 μm CMOS process. The proposed pixel consists of a specially designed n-well with a non-uniform lateral doping profile that follows a square-root spatial dependence. "Buried" MOS capacitor-based collection-gate, a transfer-gate, and an n-type MOSFET source/drain n + floating-diffusion serve to realize a non-destructive readout. The pixel readout is performed using an in-pixel source-follower pixel buffer configuration followed by an output amplifier featuring correlated double-sampling. The concentration gradient formed in the n-well employs a single extra implantation step in the 0.35 μm CMOS process mentioned and requires only a single extra mask. It generates an electrostatic potential gradient, i.e. a lateral drift-field, in the photoactive area of the pixel which enables high charge transfer speed and low image-lag. According to the simulation results presented, charge transfer times of less than 3 ns are to be expected.

  16. 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.

  17. Characterization and identification of the chemical constituents from tartary buckwheat (Fagopyrum tataricum Gaertn) by high performance liquid chromatography/photodiode array detector/linear ion trap FTICR hybrid mass spectrometry.

    PubMed

    Ren, Qiang; Wu, Caisheng; Ren, Yan; Zhang, Jinlan

    2013-02-15

    In recent years tartary buckwheat has become popular healthful food due to its antioxidant, antidiabetic and antitumor activities. However, its chemical constituents have not yet been fully characterized and identified. In this paper, a novel high performance liquid chromatography coupled with photodiode array detector and linear ion trap FTICR hybrid mass spectrometry (HPLC-PDA/LTQ-FTICRMS) method was established to characterize and identify a total of 36 compounds by a single run. The retention time, maximum UV absorption wavelength, accurate mass weight and characteristic fragment ions were collected on line. To confirm the structures, 11 compounds were isolated and identified by MS and NMR experiments. 1, 3, 6, 6'-tetra-feruloyl sucrose named taroside was a new phenlypropanoid glycoside, together with 3, 6-di-p-coumaroyl-1, 6'-di-feruloyl sucrose, 1, 6, 6'-tri-feruloyl-3-p-coumaroyl sucrose, N-trans-feruloyltyramine and quercetin-3-O-[β-D-xyloxyl-(1→2)-α-L-rhamnoside] were isolated for the first time from the Fagopyrum species. The research enriched the chemical information of tartary buckwheat. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. 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.

  19. High-power flip-chip mounted photodiode array.

    PubMed

    Cross, Allen S; Zhou, Qiugui; Beling, Andreas; Fu, Yang; Campbell, Joe C

    2013-04-22

    Four-element modified uni-traveling-carrier (MUTC) photodiode arrays (PDA) flip-chip bonded onto transmission lines on AlN substrates are demonstrated. High RF output powers of 26.2 dBm and 21.0 dBm are achieved at 35 GHz and 48 GHz, respectively, using a PDA with 28-μm diameter photodiodes. A systematic comparison between a PDA with four 20 μm-diameter elements and a discrete detector with the same active area (40-μm diameter) is presented. The PDA achieved higher output power and thermal dissipation compared to its discrete counterpart.

  20. Some studies of avalanche photodiode readout of fast scintillators

    SciTech Connect

    Holl, I.; Lorenz, E.; Natkaniez, S.; Renker, D.; Schmelz, C. |; Schwartz, B.

    1995-08-01

    Photomultipliers (PMs) are the classical readout element for scintillation detectors in high energy particle physics, nuclear physics, medical physics, industrial radiation monitors etc. Here, large area avalanche photodiodes with high performance, narrow operation tolerances and high reliability have recently become available. The authors report on some tests of their performance in the readout of fast scintillators.

  1. Absolute light and resolution measurements for sensitive CsI(Tl)/photodiode detectors

    NASA Astrophysics Data System (ADS)

    Meier, Michael M.

    2003-01-01

    To conserve volume and power, photodiode/scintillator combinations are strong candidates for gamma-ray detection in space applications. High sensitivity to MeV gamma rays necessitates large-volume scintillators, which are most effectively read out with large-area photodiodes. However, because photodiodes have unity gain, the electronic noise limits resolution, and therefore small-area photodiodes that minimize capacitance are preferred. Thus, optimization of resolution involves maximizing light production and transport in the scintillator and light collection in the photodiode, while minimizing photodiode area. Measurements of performance are reported for 1×1×1cm3/10×10mm2, 80cm3/18×18mm2, and 85cm3/10×10mm2 CsI(Tl)/photodiode combinations. Each large scintillator was a single crystal, machined to a geometry that comprised a 40mm diameter × 50mm height cylindrical section that was extended through a 20°conical section to a square face that matched the respective photodiode sensitive surface. Absolute scales were estimated for the light output by measuring the photodiode responses to 241Am (59.54keV), 57Co (122.06 and 136.47keV), and 133Ba (80.99keV) and assuming a value of 3.67eV/electron-hole pair. The photodiode quantum efficiencies for the CsI(Tl) emission spectrum, corrected for Si reflection back into the scintillator, was taken to be 0.835. We obtained values of 58.2, 46.7, and 34.6 photons/keV for the combined light production and transport into the CsI for the 1cm3, ~80cm3, and ~85cm3 detectors, respectively. The best measured resolutions at 662keVfor the detectors were 5.9%, 7.2%, and 7.4% FWHM, respectively.

  2. Photodiode circuits for retinal prostheses.

    PubMed

    Loudin, J D; Cogan, S F; Mathieson, K; Sher, A; Palanker, D V

    2011-10-01

    Photodiode circuits show promise for the development of high-resolution retinal prostheses. While several of these systems have been constructed and some even implanted in humans, existing descriptions of the complex optoelectronic interaction between light, photodiode, and the electrode/electrolyte load are limited. This study examines this interaction in depth with theoretical calculations and experimental measurements. Actively biased photoconductive and passive photovoltaic circuits are investigated, with the photovoltaic circuits consisting of one or more diodes connected in series, and the photoconductive circuits consisting of a single diode in series with a pulsed bias voltage. Circuit behavior and charge injection levels were markedly different for platinum and sputtered iridium-oxide film (SIROF) electrodes. Photovoltaic circuits were able to deliver 0.038 mC/cm(2) (0.75 nC/phase) per photodiode with 50- μm platinum electrodes, and 0.54-mC/cm(2) (11 nC/phase) per photodiode with 50-μ m SIROF electrodes driven with 0.5-ms pulses of light at 25 Hz. The same pulses applied to photoconductive circuits with the same electrodes were able to deliver charge injections as high as 0.38 and 7.6 mC/cm(2) (7.5 and 150 nC/phase), respectively. We demonstrate photovoltaic stimulation of rabbit retina in-vitro, with 0.5-ms pulses of 905-nm light using peak irradiance of 1 mW/mm(2). Based on the experimental data, we derive electrochemical and optical safety limits for pixel density and charge injection in various circuits. While photoconductive circuits offer smaller pixels, photovoltaic systems do not require an external bias voltage. Both classes of circuits show promise for the development of high-resolution optoelectronic retinal prostheses.

  3. 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.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    Kaminski, Yelena; Shauly, Eitan; Paz, Yaron

    2015-12-01

    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.

  6. Low latency, area, and energy efficient Hybrid Photonic Plasmonic on-chip Interconnects (HyPPI)

    NASA Astrophysics Data System (ADS)

    Sun, Shuai; Badaway, Abdel-Hameed A.; Narayana, Vikram; El-Ghazawi, Tarek; Sorger, Volker J.

    2016-03-01

    In this paper we benchmark various interconnect technologies including electrical, photonic, and plasmonic options. We contrast them with hybridizations where we consider plasmonics for active manipulation devices, and photonics for passive propagation integrated circuit elements, and further propose another novel hybrid link that utilizes an on chip laser for intrinsic modulation thus bypassing electro-optic modulation. Link benchmarking proves that hybridization can overcome the shortcomings of both pure photonic and plasmonic links. We show superiority in a variety of performance parameters such as point-to-point latency, energy efficiency, capacity, ability to support wavelength division multiplexing, crosstalk coupling length, bit flow density and Capability-to-Latency-Energy-Area Ratio.

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

    PubMed

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

    2015-02-15

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

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

    ERIC Educational Resources Information Center

    Perry, Claudia A.; Rice, Ronald E.

    1996-01-01

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

  9. Ultraviolet avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    McClintock, Ryan; Razeghi, Manijeh

    2015-08-01

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

  10. A protected area influences genotype-specific survival and the structure of a Canis hybrid zone.

    PubMed

    Benson, John F; Patterson, Brent R; Mahoney, Peter J

    2014-02-01

    It is widely recognized that protected areas can strongly influence ecological systems and that hybridization is an important conservation issue. However, previous studies have not explicitly considered the influence of protected areas on hybridization dynamics. Eastern wolves are a species of special concern and their distribution is largely restricted to a protected population in Algonquin Provincial Park (APP), Ontario, Canada, where they are the numerically dominant canid. We studied intrinsic and extrinsic factors influencing survival and cause-specific mortality of hybrid and parental canids in the three-species hybrid zone between eastern wolves, eastern coyotes, and gray wolves in and adjacent to APP. Mortality risk for eastern wolves in areas adjacent to APP was significantly higher than for other sympatric Canis types outside of APP, and for eastern wolves and other canids within APP. Outside of APP, the annual mortality rate of all canids by harvest (24%) was higher than for other causes of death (4-7%). Furthermore, eastern wolves (hazard ratio = 3.5) and nonresidents (transients and dispersing animals, hazard ratio = 2.7) were more likely to die from harvest relative to other Canis types and residents, respectively. Thus, eastern wolves dispersing from APP were especially vulnerable to harvest mortality. For residents, eastern wolf survival was more negatively influenced by increased road density than for other Canis types, further highlighting the sensitivity of eastern wolves to human disturbance. A cycle of dispersal from APP followed by high rates of mortality and hybridization appears to maintain eastern wolves at low density adjacent to APP, limiting the potential for expansion beyond the protected area. However, high survival and numerical dominance of eastern wolves within APP suggest that protected areas can allow rare hybridizing species to persist even if their demographic performance is compromised and barriers to hybridization are largely

  11. Interference effects in reticon photodiode array detectors.

    PubMed

    Mount, G H; Sanders, R W; Brault, J W

    1992-03-01

    A detector system incorporating the Reticon RL1024S photodiode array has been constructed at the National Oceanic and Atmospheric Administration Aeronomy Laboratory 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%. The detector, manufactured by EG&G Reticon, exhibits superior signal-to-noise characteristics at the light levels characteristic of scattered skylights, but interference in the passivating layer (a thin layer of SiO(2) that is deposited during the manufacture to protect the silicon active area from water vapor) causes major problems in achieving the required precision. The mechanism of the problems and the solution we have implemented are described in detail.

  12. Recent advances in organic photodiodes (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kippelen, Bernard; Khan, Talha M.; Fuentes-Hernandez, Canek; Diniz, Larissa; Lukens, Julia M.; Larrain, Felipe

    2016-09-01

    Although the detection of photons is ubiquitous, man-made photon detectors still limits the effectiveness of applications such as light/laser detection, photography, astronomy, quantum information science, medical imaging, microscopy, communications, and others. The performance of the technologically most advanced detectors based on CMOS semiconductor technology has improved during the last decades but at the detriment of increased complexity, higher cost, limited portability and compactness, and limited area. On the other hand, nature has produced a relatively simple detector with remarkable properties: the human eye. The exploration of new paradigms in photon detection using new material platforms might therefore provide a path to further challenge the frontiers of applications enabled by light. In this talk, we will report on the realization of solution-processed organic semiconductor visible spectrum photodetectors with a high specific detectivity above 1014 Jones, at least an order of magnitude larger than values found in photodiodes based on silicon. These detectors demonstrate a sub-pA current under reverse bias in the dark, making them suitable for detecting very low levels of light. The small dark current under reverse bias allows the characterization of these devices over 9 orders of magnitude of increasing light irradiance. The detectors are based on the device structure: tin-doped indium oxide / ethoxylated polyethylenimine / poly(3-hexylthiophene) : indene C60 bisadduct / molybdenum oxide / silver and present a path toward fabrication on flexible substrates. We will show that these detectors can operate over a large dynamic range in the self-powered photovoltaic mode where the light produces a photovoltage that can be measured directly without any external bias source. We believe that large-area flexible photodetectors with detectivity values comparable to or better than those displayed by silicon-based photodiodes will enable a wide variety of

  13. Electronic Hybridization of Large-Area Stacked Graphene Films

    DTIC Science & Technology

    2013-01-01

    synthesis and characterization of coupled bilayer graphene films that exhibit intimate contact over macroscopic areas (>cm2). The observation of... Graphene films were grown via low-pressure chem- ical vapor deposition ( CVD ) in Cu foil enclosures29 and transferred onto SiO2(100 nm)/Si substrates...and isopropyl alcohol, and dried with N2. Bilayer samples are generated by sequentially transferring a second CVD graphene layer onto the graphene /SiO2

  14. Macrolide Hybrid Compounds: Drug Discovery Opportunities in Anti- Infective and Anti-inflammatory Area.

    PubMed

    Paljetak, Hana Cipcic; Tomaskovic, Linda; Matijasic, Mario; Bukvic, Mirjana; Fajdetic, Andrea; Verbanac, Donatella; Peric, Mihaela

    2017-01-01

    Macrolides, polyketide natural products, and their 15-membered semi-synthetic derivatives are composed of substituted macrocyclic lactone ring and used primarily as potent antibiotics. Recently their usefulness was extended to antimalarial and anti-inflammatory area. Hybrid macrolides presented in this article are the next generation semi-synthetic compounds that combine pharmacophores from antibacterial, antimalarial and anti-inflammatory area with 14- and 15-membered azalide scaffolds. Antibacterial azalide hybrids with sulphonamides showed improved activity against resistant streptococci while quinolone conjugates demonstrated full coverage of respiratory pathogens including macrolide resistant strains and their efficacy was confirmed in mouse pneumonia model. Antimalarial macrolide hybrids, mainly involving (chloro)quinoline pharmacophores, showed outstanding activity against chloroquine resistant strains, favourable pharmacokinetics, promising in vivo efficacy as well as encouraging developmental potential. Anti-inflammatory hybrids were obtained by combining macrolides with corticosteroid and non-steroidal anti-inflammatory drugs. They were found active in in vivo animal models of locally induced inflammation, asthma, inflammatory bowel disease and rheumatoid arthritis and demonstrated improved safety over parent steroid drugs. Overall, macrolide hybrids possess significant potential to be developed as potent novel medicines in therapeutic areas of utmost pharmaceutical interest. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  15. 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.

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

    ERIC Educational Resources Information Center

    Perry, Claudia A.; Rice, Ronald E.

    1998-01-01

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

  17. PiN photodiode performance comparison for dosimetry in radiology applications.

    PubMed

    Oliveira, Charles N P; Khoury, Helen J; Santos, Edval J P

    2016-12-01

    Performance comparison of selected photodiodes for usage as radiation detectors for radio-protection is presented. In this study, based on the criteria of minimum sensitive area of 5mm(2), minimum half angle 60° and low cost, four commercial photodiodes are selected for evaluation: SFH205, SFH206, BPW34, and BPX90F. Photodiodes are low cost, small volume and lightweight detectors. As an electronic transducer, photodiode detector is an attractive approach for the development of low power portable electronic dosimeter for direct-reading real-time radiation dose measurement. The devices have been studied with respect to sensitivity (efficiency) in X-rays and gamma rays detection, repeatability and linearity in air kerma.

  18. Avalanche photodiodes for anticoincidence detectors

    NASA Astrophysics Data System (ADS)

    Cirignano, Leonard J.; Farrell, Richard; Redus, Robert H.; Squillante, Michael R.; Hunter, Stanley D.; Cuddapah, Rajani; Mukherjee, Reshmi

    1996-10-01

    Anticoincidence detectors are required for a variety of satellite instruments, including high energy gamma-ray telescopes, in order to differentiate ambient background radiation from signals of interest. Presently, most anticoincidence systems use scintillators coupled to photomultiplier tubes. We have demonstrated that it is now possible to use very high gain solid state avalanche photodiodes (APDs) as photodetectors for this application. A single APD coupled to a 30 cm multiplied by 30 cm multiplied by 0.95 cm plastic scintillator tile demonstrated 100% detection efficiency for minimum ionizing particles, with a low false positive rate. Multiple APDs enhance the signal to noise ratio in addition to providing redundancy. Relative to PMTs, APDs are compact, low power, and mechanically robust devices. Ground test data of APDs for anticoincidence shields is presented.

  19. Organic photodiodes for biosensor miniaturization.

    PubMed

    Wojciechowski, Jason R; Shriver-Lake, Lisa C; Yamaguchi, Mariko Y; Füreder, Erwin; Pieler, Roland; Schamesberger, Martin; Winder, Christoph; Prall, Hans Jürgen; Sonnleitner, Max; Ligler, Frances S

    2009-05-01

    Biosensors have successfully demonstrated the capability to detect multiple pathogens simultaneously at very low levels. Miniaturization of biosensors is essential for use in the field or at the point of care. While microfluidic systems reduce the footprint for biochemical processing devices and electronic components are continually becoming smaller, optical components suitable for integration--such as LEDs and CMOS chips--are generally still too expensive for disposable components. This paper describes the integration of polymer diodes onto a biosensor chip to create a disposable device that includes both the detector and the sensing surface coated with immobilized capture antibody. We performed a chemiluminescence immunoassay on the OPD substrate and measured the results using a hand-held reader attached to a laptop computer. The miniaturized biosensor with the disposable slide including the organic photodiode detected Staphylococcal enterotoxin B at concentrations as low as 0.5 ng/mL.

  20. High quantum efficiency annular backside silicon photodiodes for reflectance pulse oximetry in wearable wireless body sensors

    NASA Astrophysics Data System (ADS)

    Duun, Sune; Haahr, Rasmus G.; Hansen, Ole; Birkelund, Karen; Thomsen, Erik V.

    2010-07-01

    The development of annular photodiodes for use in a reflectance pulse oximetry sensor is presented. Wearable and wireless body sensor systems for long-term monitoring require sensors that minimize power consumption. We have fabricated large area 2D ring-shaped silicon photodiodes optimized for minimizing the optical power needed in reflectance pulse oximetry. To simplify packaging, backside photodiodes are made which are compatible with assembly using surface mounting technology without pre-packaging. Quantum efficiencies up to 95% and area-specific noise equivalent powers down to 30 fW Hz-1/2 cm-1 are achieved. The photodiodes are incorporated into a wireless pulse oximetry sensor system embedded in an adhesive patch presented elsewhere as 'The Electronic Patch'. The annular photodiodes are fabricated using two masked diffusions of first boron and subsequently phosphor. The surface is passivated with a layer of silicon nitride also serving as an optical filter. As the final process, after metallization, a hole in the center of the photodiode is etched using deep reactive ion etch.

  1. 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

    2016-06-17

    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.

  2. 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

  3. Hybrid lidar radar receiver for underwater imaging applications

    NASA Astrophysics Data System (ADS)

    Seetamraju, Madhavi; Gurjar, Rajan; Squillante, Michael; Derderian, Jeffrey P.

    2009-05-01

    In this work, we present research performed to improve the receiver characteristics for underwater imaging applications using the hybrid lidar-radar detection technique. We report the development of the next-generation coherent heterodyne receiver using modulation of the optical receiver's amplifier gain. Significant advantages in the receiver specifications are achieved using a large-area, high gain, low-noise silicon avalanche photodiode (APD) as the photodetector cum frequency mixer-demodulator. We demonstrate that heterodyne detection by gain modulation of APD can be used to increase the signal-to-noise ratio, detection sensitivity and bandwidth for the hybrid receiver system.

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  5. Heterogeneously integrated waveguide-coupled photodiodes on silicon-on-diamond (SOD)

    NASA Astrophysics Data System (ADS)

    Xie, Xiaojun; Ramaswamy, Anand; Shen, Yang; Yang, Zhanyu; Jacob-Mitos, Matt; Wang, Ye; Zang, Jizhao; Norberg, Erik; Fish, Greg; Campbell, Joe C.; Beling, Andreas

    2016-09-01

    We report on InP-based high power modified uni-traveling carrier (MUTC) photodiodes heterogeneously integrated on silicon on diamond (SOD) waveguides. Typical dark currents of MUTC photodiodes on SOD waveguides are 20 nA at - 5 V bias voltage. A 50-μm long photodiode has an internal responsivity of 1.07 A/W at 1550 nm wavelength. The bandwidths of photodiodes with active areas of 14×25 μm2, 14×50 μm2, 14×100 μm2 and 14×150 μm2 are 22 GHz, 16 GHz, 10 GHz and 7 GHz, respectively. The maximum output RF powers of 14×100 μm2 photodiodes are 13 dBm, 14.4 dBm and 15.3 dBm at 10 GHz, respectively. The maximum DC dissipated power is 0.67 W. To our knowledge, this is the first demonstration of III-V photodiodes integrated on SOD waveguides.

  6. Silicon photodiode characterization from 1 eV to 10 keV

    SciTech Connect

    Idzorek, G.C.; Bartlett, R.J.

    1997-10-01

    Silicon photodiodes offer a number of advantages over conventional photocathode type soft x-ray detectors in pulsed power experiments. These include a nominally flat response, insensitivity to surface contamination, low voltage biasing requirements, sensitivity to low energy photons, excellent detector to detector response reproducibility, and ability to operate in poor vacuum or gas backfilled experiments. Silicon photodiodes available from International Radiation Detectors (IRD), Torrance, California have been characterized for absolute photon response from 1 eV to 10 keV photon energy, time response, and signal saturation levels. The authors have assembled individually filtered photodiodes into an array designated the XUV-7. The XUV-7 provides seven photodiodes in a vacuum leak tight, electrically isolated, low noise, high bandwidth, x-ray filtered assembly in a compact package with a 3.7 cm outside diameter. In addition they have assembled the diodes in other custom configurations as detectors for spectrometers. Their calibration measurements show factor of ten deviations from the silicon photodiode theoretical flat response due to diode sensitivity outside the center `sensitive area`. Detector response reproducibility between diodes appears to be better than 5%. Time response measurements show a 10-90% rise time of about 0.1 nanoseconds and a fall time of about 0.5 nanoseconds. Silicon photodiodes have proven to be a versatile and useful complement to the standard photocathode detectors for soft x-ray measurement and are very competitive with diamond for a number of applications.

  7. Material and design engineering of (Al)GaN for high-performance avalanche photodiodes and intersubband applications

    NASA Astrophysics Data System (ADS)

    Razeghi, M.; Bayram, C.

    2009-05-01

    Numerous applications in scientific, medical, and military areas demand robust, compact, sensitive, and fast ultraviolet (UV) detection. Our (Al)GaN photodiodes pose high avalanche gain and single-photon detection efficiency that can measure up to these requirements. Inherit advantage of back-illumination in our devices offers an easier integration and layout packaging via flip-chip hybridization for UV focal plane arrays that may find uses from space applications to hostile-agent detection. Thanks to the recent (Al)GaN material optimization, III-Nitrides, known to have fast carrier dynamics and short relaxation times, are employed in (Al)GaN based superlattices that absorb in near-infrared regime. In this work, we explain the origins of our high performance UV APDs, and employ our (Al)GaN material knowledge for intersubband applications. We also discuss the extension of this material engineering into the far infrared, and even the terahertz (THz) region.

  8. 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.

  9. Simulation of hybrid wind/solar systems for typical areas of Brazil and Cuba

    SciTech Connect

    Villar Ale, J.A.; Garcia, F.H.

    1999-07-01

    Brazil and Cuba share a common history of serious problems related to the electrification of their isolated communities. Both countries have renewable resources of energy that allow, for instance, the use of photovoltaic and wind systems. These systems can be used in an integrated way, known as hybrid systems, achieving better reliability and economy. This work presents a simplified methodology for the design of such systems to be applied to the electrification of rural areas in both countries.

  10. Transparent organic photodiodes stacked with electroluminescence devices

    NASA Astrophysics Data System (ADS)

    Komatsu, Takahiro; Sakanoue, Kei; Fujita, Katsuhiko; Tsutsui, Tetsuo

    2005-10-01

    Stacked devices that consisted of transparent organic photodiodes (TOPDs) and organic electroluminescence devices (OELs) were demonstrated. TOPDs were prepared by poly-(2-methoxy-5- (2'-ethylhexyloxy)-1,4-phenylene vinylene (MEH-PPV) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blend films as an active layer and transparent Au cathode (10 nm thick). These TOPDs showed about 45 % transmittance on average in visible light region (380-780 nm) and good correlation between incident light intensity and output photocurrent. Based on these results, the stacked devices were prepared by introducing OELs on TOPDs through a SiO insulating layer. The structure of OELs was ITO/Carbon/TPD/Alq3/LiF/Al. These stacked devices work as light emitting devices and also photo diodes. Since TOPDs have transparency, OELs can illuminate a paper put on the glass substrate through TOPDs and TOPDs can receive reflective light from the paper. Although the TOPDs also absorb light from OELs directly, the output signals from TOPDs changed according to the black and white pattern of the paper. These results show that the devices act as an image sensor having light emitting layer and light receiving layer in a same area.

  11. A hybrid fuzzy weight of evidence method in landslide susceptibility analysis on the Wuyuan area, China

    NASA Astrophysics Data System (ADS)

    Hong, Haoyuan; Ilia, Ioanna; Tsangaratos, Paraskevas; Chen, Wei; Xu, Chong

    2017-08-01

    The present study proposed a hybrid fuzzy weight of evidence model for constructing a landslide susceptibility map in the Wuyuan area, China, where disastrous landslide events have occurred. The model combines the knowledge of experts obtained through a fuzzy logic approach and a hybrid weight of evidence method. The estimated knowledge-based fuzzy membership value of each environmental variable is combined with data-based conditional probabilities to derive fuzzy posterior probabilities and landslide susceptibility. The developed model was compared with a landslide susceptibility map produced using the data-driven weight of evidence method, based on 510 landslide and non-landslide sites. The sites were identified by analyzing airborne imagery, field investigation and previous studies. Landside susceptibility for these sites was analyzed using 10 geo-environmental variables: slope, aspect, lithology, soil, rainfall, plan curvature, the normalized difference vegetation index, distance to roads, distance to rivers and distance to faults. The resultant hybrid fuzzy weight of evidence method showed high predictive power, with the area under the success and predictive curves being 0.770 and 0.746, respectively. Additional analyses showed that the developed model could work effectively even with limited data.

  12. Silicon avalanche photodiodes for direct detection of X-rays.

    PubMed

    Baron, Alfred Q R; Kishimoto, Shunji; Morse, John; Rigal, Jean Marie

    2006-03-01

    Silicon avalanche photodiodes (APDs) are discussed as fast X-ray detectors for synchrotron radiation. The emphasis is on ;direct' detection, where the X-ray is absorbed within the silicon APD itself, and, therefore, on use with medium-energy X-rays, <30 keV. The impact of APD structure on device performance is examined, and representative data from many different commercial devices are presented. Specific areas discussed include signal shapes, high-rate behavior, time resolution and pulse-height response. Data from several APD arrays are also presented, as is a detailed description of an integrated package system. Tables are included comparing commercially available devices, including arrays.

  13. 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.

  14. 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.

  15. Multichannel intensified photodiode for near infrared single photon detection

    NASA Astrophysics Data System (ADS)

    Aebi, Verle W.; Sykora, Derek F.; Jurkovic, Michael J.; Costello, Kenneth A.

    2011-05-01

    An overview of the Intensified Photodiode (IPD) is presented with an emphasis on IPDs optimized for use in the 950nm to 1350nm spectral range for single photon detection applications. The theory of operation of the IPD, two different electron optics designs, and device performance for a multichannel, 4x4 pixel array, low jitter IPD optimized for operation at 1060nm are presented in this paper. Key results include greater than 15% quantum efficiency, large active area, and less than 550ps impulse response.

  16. Effect of temperature on silicon PIN photodiode radiation detectors

    NASA Astrophysics Data System (ADS)

    Kim, Han Soo; Jeong, Manhee; Kim, Young Soo; Ha, Jang Ho; Cho, Seong Yeon

    2014-03-01

    One of the noise sources of a semiconductor radiation detector is thermal noise, which degrades the performance, such as the energy resolution and unexpected random pulse signals. In this study, PIN photodiode radiation detectors, with different active areas were designed and fabricated for an experimental comparison of the energy resolutions for different temperatures and capacitances by using a Ba-133 calibration gamma-ray source. The experimental temperature was approximately in the range from -7 to 24 °C and was controlled by using a peltier device. The design considerations and the electrical characteristics, such as the I-V and the C-V characteristics, are also addressed.

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

    SciTech Connect

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

    2016-03-29

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  19. Improved Photoresponse of Hybrid ZnO/P3HT Bilayered Photodetector Obtained Through Oriented Growth of ZnO Nanorod Arrays and the Use of Hole Injection Layer

    NASA Astrophysics Data System (ADS)

    Bilgaiyan, Anubha; Dixit, Tejendra; Palani, I. A.; Singh, Vipul

    2015-08-01

    We report highly oriented one-dimensional (1-D) growth of zinc oxide (ZnO) nanorod arrays (NRA) which were later utilized to fabricate hybrid photodiodes having the typical photodiode configuration of indium tin oxide (ITO)/ZnO/poly(3-hexylthiophene) (P3HT)/Ag. These functional hybrid bilayered photodiodes were found to have high rectification ratio under dark conditions and demonstrated enhanced responsivity under light illumination. Further, we studied the effect of an intermediate electron blocking layer of poly(ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) on the photodiode characteristics and demonstrated ITO/ZnO/P3HT/PEDOT:PSS/Ag photodiodes, reporting very high rectification ratio and responsivity in this bilayered configuration. The observed results are explained on the basis of the increased surface area of contact between the ZnO nanorods and the P3HT, and also the efficient hole injection into the P3HT layer from the top Ag electrode.

  20. 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.

  1. 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.

  2. Note: Galvanic isolated voltage source using a single photodiode.

    PubMed

    Stoican, O S

    2010-04-01

    A galvanic isolated voltage source able to provide several volts by using a single photodiode is described. A pulse-modulated laser beam is sent to a photodiode. By using a step-up transformer the amplitude of the variable voltage generated by the photodiode is increased. Adding a rectifier cell the variable voltage is converted back into a dc voltage.

  3. Organic light detectors: photodiodes and phototransistors.

    PubMed

    Baeg, Kang-Jun; Binda, Maddalena; Natali, Dario; Caironi, Mario; Noh, Yong-Young

    2013-08-21

    While organic electronics is mostly dominated by light-emitting diodes, photovoltaic cells and transistors, optoelectronics properties peculiar to organic semiconductors make them interesting candidates for the development of innovative and disruptive applications also in the field of light signal detection. In fact, organic-based photoactive media combine effective light absorption in the region of the spectrum from ultraviolet to near-infrared with good photogeneration yield and low-temperature processability over large areas and on virtually every substrate, which might enable innovative optoelectronic systems to be targeted for instance in the field of imaging, optical communications or biomedical sensing. In this review, after a brief resume of photogeneration basics and of devices operation mechanisms, we offer a broad overview of recent progress in the field, focusing on photodiodes and phototransistors. As to the former device category, very interesting values for figures of merit such as photoconversion efficiency, speed and minimum detectable signal level have been attained, and even though the simultaneous optimization of all these relevant parameters is demonstrated in a limited number of papers, real applications are within reach for this technology, as it is testified by the increasing number of realizations going beyond the single-device level and tackling more complex optoelectronic systems. As to phototransistors, a more recent subject of study in the framework of organic electronics, despite a broad distribution in the reported performances, best photoresponsivities outperform amorphous silicon-based devices. This suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto-electronic switch and memory.

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

    PubMed

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

    2013-07-29

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

  5. 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)

  6. Photodiode and photomultiplier areal sensitivity anomalies

    NASA Technical Reports Server (NTRS)

    Youngbluth, O., Jr.

    1977-01-01

    Several silicon photodiodes and photomultipliers were tested to determine signal variations as a light spot was scanned over the photosensitive surface of these detectors. Qualitative and quantitative data is presented to demonstrate the areal sensitivity anomalies. These anomalies are related back to the fabrication techniques of the manufacturers.

  7. 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.

  8. A photodiode based miniature sun sensor

    NASA Astrophysics Data System (ADS)

    Lü, Xiaozhou; Tao, Yebo; Xie, Kai; Wang, Songlin; Li, Xiaoping; Bao, Weimin; Chen, Renjie

    2017-04-01

    The solar vector is one of the most important parameters for attitude control of nanosatellites. This attitude control must be achieved without the sensors adding significantly to its size or mass. This paper presents a photodiode-based miniature sun sensor, which consists of two triangular pyramidal sensor unit structures, with each unit comprising three micro-silicon photodiodes. The two sensor units are installed on the diagonal of the nanosatellite to form a complete sun sensor capable of achieving a full-field range of solar vector measurements. In this paper, the mathematical model of the short-circuit currents of the silicon photodiodes as a function of the solar vector coordinates is deduced. A sensor sample was built and installed on a nanosatellite model, and the temperature compensation coefficient of the silicon photodiodes was obtained experimentally. The dynamic characteristic, linearity, hysteresis and repeatability of the component were measured. The sun sensor introduced in this paper can be placed on any satellite platform to allow a full range solar vector measurement, and this would result in an increase of only 1.86 g and 0.9 cm3 of the satellite’s mass and volume, respectively.

  9. Fabrication and characterization of Au/n-Si photodiode with lithium as back-surface-field

    NASA Astrophysics Data System (ADS)

    Keffous, A.; Zitouni, M.; Belkacem, Y.; Menari, H.; Chergui, W.

    2002-10-01

    In this work, we present a design and characterization of Schottky barrier Au/n-Si/Li based UV-VIS photodiode for application, such as solar UV monitoring, flame sensors and UV astronomy. The Schottky photodiode was realized with a thin layer of gold (Au) at the front side of high purity n-type silicon and lithium (Li) on the back side as back-surface-field (Li-BSF). The Li-BSF used was a new method which allow us to modulate and choice the depletion width. I- V characteristic, capacitance and spectral response were performed, the results were found in agreement with those determined by simulation method. A quantum efficiency (QE) of 47% at about 550 nm wavelength was obtained using only a thin gold layer as sensitive area. The thickness of gold used on the photodiode was around 125 Å, where 58% of light transmission was carried out.

  10. Silicon photodiode soft x-ray detectors for pulsed power experiments

    SciTech Connect

    Idzorek, G.C.; Bartlett, R.J.

    1997-10-01

    Silicon photodiodes offer a number of advantages over conventional photocathode type soft x-ray detectors in pulsed power experiments. These include a nominally flat response, insensitivity to surface contamination, low voltage biasing requirements, sensitivity to low energy photons, excellent detector to detector response reproducibility, and ability to operate in poor vacuum or gas backfilled experiments. Silicon photodiodes available from International Radiation Detectors (IRD), Torrance, California have been characterized for absolute photon response from 1 eV to 10 keV photon energy, time response, and signal saturation levels. The authors calibration measurements show factor of ten deviations from the silicon photodiode theoretical flat response due to diode sensitivity outside the center `sensitive area`. Detector response reproducibility between diodes appears to be better than 5%. Time response measurements show a 10-90% rise time of about 0.1 nanoseconds and a fall time of about 0.5 nanoseconds.

  11. 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.

  12. 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.

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

    PubMed

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

    2014-06-24

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

  14. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    PubMed Central

    Cho, Namchul; Li, Feng; Turedi, Bekir; Sinatra, Lutfan; Sarmah, Smritakshi P.; Parida, Manas R.; Saidaminov, Makhsud I.; Murali, Banavoth; Burlakov, Victor M.; Goriely, Alain; Mohammed, Omar F.; Wu, Tom; Bakr, Osman M.

    2016-01-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microarrays that are distinguishable from general polycrystalline perovskite materials in terms of their crystal orientation, film morphology and electronic properties. X-ray diffraction patterns reveal that the film is strongly oriented in the (112) and (200) planes parallel to the substrate. This film is structurally confined by directional crystal growth, inducing intense anisotropy in charge transport. In addition, the low trap-state density (7.9 × 1013 cm−3) leads to strong amplified stimulated emission. This ability to control crystal orientation and morphology could be widely adopted in optoelectronic devices. PMID:27830694

  15. Comparative study of fuel cell, battery and hybrid buses for renewable energy constrained areas

    NASA Astrophysics Data System (ADS)

    Stempien, J. P.; Chan, S. H.

    2017-02-01

    Fuel cell- and battery-based public bus technologies are reviewed and compared for application in tropical urban areas. This paper scrutinizes the reported literature on fuel cell bus, fuel cell electric bus, battery electric bus, hybrid electric bus, internal combustion diesel bus and compressed natural gas bus. The comparison includes the capital and operating costs, fuel consumption and fuel cycle emissions. To the best of authors knowledge, this is the first study to holistically compare hydrogen and battery powered buses, which is the original contribution of this paper. Moreover, this is the first study to focus on supplying hydrogen and electricity from fossil resources, while including the associated emissions. The study shows that compressed natural gas and hybrid electric buses appear to be the cheapest options in terms of total cost of ownership, but they are unable to meet the EURO VI emissions' standard requirement. Only fuel cell based buses have the potential to achieve the emissions' standard when the fuel cycle based on fossil energy was considered. Fuel cell electric buses are identified as a technology allowing for the largest CO2 emission reduction, making ∼61% decrease in annual emissions possible.

  16. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    NASA Astrophysics Data System (ADS)

    Cho, Namchul; Li, Feng; Turedi, Bekir; Sinatra, Lutfan; Sarmah, Smritakshi P.; Parida, Manas R.; Saidaminov, Makhsud I.; Murali, Banavoth; Burlakov, Victor M.; Goriely, Alain; Mohammed, Omar F.; Wu, Tom; Bakr, Osman M.

    2016-11-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microarrays that are distinguishable from general polycrystalline perovskite materials in terms of their crystal orientation, film morphology and electronic properties. X-ray diffraction patterns reveal that the film is strongly oriented in the (112) and (200) planes parallel to the substrate. This film is structurally confined by directional crystal growth, inducing intense anisotropy in charge transport. In addition, the low trap-state density (7.9 × 1013 cm-3) leads to strong amplified stimulated emission. This ability to control crystal orientation and morphology could be widely adopted in optoelectronic devices.

  17. Learning strategies used by undergraduate and postgraduate students in hybrid courses in the area of health.

    PubMed

    Peixoto, Henry Maia; Peixoto, Mariana Maia; Alves, Elioenai Dornelles

    2012-01-01

    This study aimed to investigate the learning habits and strategies of undergraduate and post-graduate students matriculated in hybrid courses in the area of healthcare at a Brazilian university. 220 graduate students were invited to participate in the research, of whom 67.27% accepted. An exploratory methodology was utilized, which analyzed quantitative data collected by a structured instrument. A similarity may be observed between undergraduate and postgraduate students concerning the majority of education habits and learning strategies, such as the large proportion of those who read more than half of the course content and of those who preferred to study alone, as well as in the high use of the majority of strategies evaluated. It is concluded that both the groups present appropriate study habits and satisfactorily used the learning strategies investigated.

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

    SciTech Connect

    Wardle, K.E.

    2013-07-01

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

  19. The large-area hybrid-optics RICH detector for the CLAS12 spectrometer

    DOE PAGES

    Mirazita, M.; Angelini, G.; Balossino, I.; ...

    2017-01-16

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

  20. Hybrid approach using TOPLATS and regression model for forecasting flash flood in mountainous area

    NASA Astrophysics Data System (ADS)

    Lee, B. J.; Yoon, S.

    2016-12-01

    A number of recent studies based on observation and climate modeling have reported Korea to be highly vulnerable to global warming, in particular for water resources. As Korea is exposed to flood hazards due to nature patterns, such as the concentrated annual precipitation in which approximately two thirds of the total precipitation is received during the summer monsoon season. The objective of this study is to develop the hybrid approach using the gridded hydrologic components of TOPLATS land surface model and statistic flash flood index model. The accuracy of this method is also examined in this study. The study area is the national capital region of Korea, and 38 flash flood damages had occurred from 2009 to 2013. The spatio-temporal resolutions of land surface model are 1h and 1 km, respectively. The gridded meteorological data are generated using the inverse distance weight method with automatic weather stations (AWSs) of Korea Meteorological Administration (KMA). The hydrological components, (e.g., surface runoff, soil water contents, and water table depth) of cells corresponding to the positions of 38 flood damages reasonably respond to the cell based hourly rainfalls. Under the total rainfall condition, the gridded flash flood index shows 71% to 87% from 4 h to 6 h in the lead time based on the rescue request time and 42% to 52% of accuracy at 0 h which means that the time period of the lead time is in a limited rescue request time. From these results, it is known that the hybrid approach using the cell based hydrological components from land surface model and the statistic flash flood index model has a capability in forecasting flash flood in the mountainous area.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  2. 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.

  3. Recent advances in avalanche photodiode technology

    NASA Astrophysics Data System (ADS)

    Squillante, Michael R.; Gordon, Jeffrey S.; Farrell, Richard; Vasile, Stefan A.; Daley, Kathleen; Oakes, Carlton E.; Vanderpuye, K.

    1993-12-01

    Avalanche photodiodes (APDs) are solid state devices having an internal signal gain which gives them a better signal-to-noise ratio than standard photodiodes. Although they have been studied for years, recent advances in the fabrication techniques have allowed the construction of multielement arrays (up to 10 X 10) with high performance capability. This progress has resulted in increased potential for exploiting the advantages of APDs in a variety of important applications including measurements requiring fast response such as nuclear and high energy physics research, industrial nondestructive testing, medical instrumentation, and biomedical research using low energy particles. Recent experimental data characterizing APDs and APD arrays used as x-ray, particle, and low level light detectors are presented.

  4. Reduction of Photodiode Nonlinearities by Adaptive Biasing

    DTIC Science & Technology

    2016-10-14

    on modulated optical carriers as a method of transporting high frequency and microwave information over sizeable distances. If the system bandwidth...Williams I EXECUTIVE SUMMARY RF photonic links impress information on modulated optical carriers as a method of transporting high frequency and microwave ...boards, and the light from each is combined and sent to the photodiode under test. Polarization rotators permitted the states of polarization to be

  5. Shot noise suppression in avalanche photodiodes.

    PubMed

    Ma, Feng; Wang, Shuling; Campbell, Joe C

    2005-10-21

    We identify a new shot noise suppression mechanism in a thin (approximately 100 nm) heterostructure avalanche photodiode. In the low-gain regime the shot noise is suppressed due to temporal correlations within amplified current pulses. We demonstrate in a Monte Carlo simulation that the effective excess noise factors can be < 1, and reconcile the apparent conflict between theory and experiments. This shot noise suppression mechanism is independent of known mechanisms such as Coulomb interaction, or reflection at heterojunction interfaces.

  6. 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

  7. 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.

  8. Silicon photodiodes with high photoconductive gain at room temperature.

    PubMed

    Li, X; Carey, J E; Sickler, J W; Pralle, M U; Palsule, C; Vineis, C J

    2012-02-27

    Silicon photodiodes with high photoconductive gain are demonstrated. The photodiodes are fabricated in a complementary metal-oxide-semiconductor (CMOS)-compatible process. The typical room temperature responsivity at 940 nm is >20 A/W and the dark current density is ≈ 100 nA/cm2 at 5 V reverse bias, yielding a detectivity of ≈ 10(14) Jones. These photodiodes are good candidates for applications that require high detection sensitivity and low bias operation.

  9. 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.

  10. A Hybrid Variational-Ensemble data assimilation scheme with systematic error correction for limited area ocean models

    NASA Astrophysics Data System (ADS)

    Oddo, Paolo; Storto, Andrea; Dobricic, Srdjan; Russo, Aniello; Lewis, Craig; Onken, Reiner; Coelho, Emanuel

    2017-04-01

    A hybrid variational-ensemble data assimilation scheme to estimate the vertical and horizontal components of the background-error covariance matrix for an ocean variational data assimilation system is presented and tested in a limited area ocean model. The high resolution limited area model is implemented in the western Mediterranean Sea where an extensive dataset has been collected during the Recognized Environmental Picture Experiments (REP14-MED) conducted in June 2014 by the Centre for Maritime Research and Experimentation with several partners. Observational data is used for assimilation and validation purposes. The hybrid scheme is used both to correct the systematic error introduced in the system from the external forcing (initialization, lateral and surface open boundary conditions) and model parameterization and to improve the representation of small scale errors in the background error covariance matrix. A 14-members ensemble system generated through perturbation of assimilated observations is run off-line for further use in the hybrid scheme. Results of four different experiments are compared. The reference experiment uses the classical stationary formulation of the background error covariance matrix and has no systematic error correction. The other three experiments account, or not, for systematic error correction and hybrid background error covariance matrix combining the static and the ensemble derived errors of the day. Results show that the hybrid scheme when used in conjunction with the systematic error correction reduces the mean absolute error of temperature and salinity misfit by 55% and 42% respectively versus statistics arising from standard climatological covariances without systematic error correction.

  11. Integrated organic optical sensor arrays based on ring-shaped organic photodiodes

    NASA Astrophysics Data System (ADS)

    Sagmeister, Martin; Lamprecht, Bernhard; Kraker, Elke; Haase, Anja; Jakopic, Georg; Köstler, Stefan; Ditlbacher, Harald; Galler, Nicole; Abel, Tobias; Mayr, Torsten

    2011-10-01

    We present an integrated optical sensor platform suitable for the parallel detection of multiple parameters in an array format. This sensor technology combines fluorescent sensor layers with ring-shaped thin-film organic photodiodes (OPDs), serving as integrated fluorescence detectors. The sensing layers are deposited by screen-printing on the upper side of a PET substrate, which is exposed to an analyte, whereas the ring-shaped photodiodes are monolithically integrated, by vapour phase deposition, on the backside of the transparent substrate, in correct alignment to the sensing layers. The monolithic integration of sensor layers and detectors on one common substrate as well as the special ring shaped form of the photodiodes guarantees that a maximum of the fluorescent light emitted from the sensor layers is collected. A key advantage of the above described sensor geometry is the straightforward potential to realise sensor arrays for the parallel detection of multiple parameters: different sensor spots are illuminated by commercial LEDs or alternatively with one large area OLED, and are read-out by individual integrated organic photodiodes, surrounding the respective sensor layers. Three different sensing principles including absorption, fluorescence and surface plasmon resonance can be applied in the same basic sensor platform. The functionality of the concept is demonstrated by an integrated oxygen sensor. Sensor schemes for the analytical parameters carbon dioxide, temperature and ammonia, are proposed. Efficient front end electronics enabling intensity and time domain detection of sensor signals for the testing and characterisation of the integrated sensor devices have been developed.

  12. Near-unity quantum efficiency of broadband black silicon photodiodes with an induced junction

    NASA Astrophysics Data System (ADS)

    Juntunen, Mikko A.; Heinonen, Juha; Vähänissi, Ville; Repo, Päivikki; Valluru, Dileep; Savin, Hele

    2016-12-01

    Ideal photodiodes can detect all incoming photons independently of the wavelength, angle or intensity of the incident light. Present-day photodiodes notably suffer from optical losses and generated charge carriers are often lost via recombination. Here, we demonstrate a device with an external quantum efficiency above 96% over the wavelength range 250-950 nm. Instead of a conventional p-n junction, we use negatively charged alumina to form an inversion layer that generates a collecting junction extending to a depth of 30 µm in n-type silicon with bulk resistivity larger than 10 kΩ cm. We enhance the collection efficiency further by nanostructuring the photodiode surface, which results in higher effective charge density and increased charge-carrier concentration in the inversion layer. Additionally, nanostructuring and efficient surface passivation allow for a reliable device response with incident angles up to 70°. We expect the considered device to improve data quality, reduce the area of photodiodes as well as decrease the cost per pixel.

  13. 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.

  14. 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.

  15. Feedback in close-coupled axial VCSEL-photodiode pairs

    NASA Astrophysics Data System (ADS)

    Geib, Kent M.; Serkland, Darwin K.; Peake, Gregory M.; Sanchez, Victoria M.

    2011-03-01

    We have been investigating the use of coaxial multimode VCSEL/PD (vertical cavity surface emitting laser/photodiode) pairs for positional sensing with emitter to target mirror distances on the order of 1mm. We have observed large variations in signal levels due to the strong optical feedback in these close-coupled systems, employing either heterogeneously integrated commercial components or our own monolithically integrated devices. The feedback effect is larger than anticipated due to the annular geometry of the photodetector. Even though there is very little change in the measured VCSEL total output power, the optical feedback induces variations in the transverse mode distributions in these multimode VCSELs. The higher order modes have a larger divergence angle resulting in changes in the reflected light power incident upon the active detector area for a large range of emitter/mirror separations. We will review the experimental details and provide strategies for avoiding these variations in detected power.

  16. Hybrid ARQ Error-Controlling Scheme for Robust and Efficient Transmission of UWB Body Area Networks

    NASA Astrophysics Data System (ADS)

    Suzuki, Haruka; Hernandez, Marco; Kohno, Ryuji

    This paper presents hybrid type-II automatic repeat request (H-ARQ) for wireless wearable body area networks (BANs) based on ultra wideband (UWB) technology. The proposed model is based on three schemes, namely, high rate optimized rate compatible punctured convolutional codes (HRO-RCPC), Reed Solomon (RS) invertible codes and their concatenation. Forward error correction (FEC) coding is combined with simple cyclic redundancy check (CRC) error detection. The performance is investigated for two channels: CM3 (on-body to on-body) and CM4 (on-body to a gateway) scenarios of the IEEE802.15.6 BAN channel models for BANs. It is shown that the improvement in performance in terms of throughput and error protection robustness is very significant. Thus, the proposed H-ARQ schemes can be employed and optimized to suit medical and non-medical applications. In particular we propose the use of FEC coding for non-medical applications as those require less stringent quality of service (QoS), while the incremental redundancy and ARQ configuration is utilized only for medical applications. Thus, higher QoS is guaranteed for medical application of BANs while allowing coexistence with non-medical applications.

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

    PubMed Central

    Gui, Chengcheng; Wang, Jian

    2015-01-01

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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Study on the relationship of dark current characteristics and materials surface defects of extended wavelength InGaAs photodiodes

    NASA Astrophysics Data System (ADS)

    Yan, Hongzhou; Tang, Hengjing; Deng, Shuangyan; Chen, Gang; Shao, Xiumei; Li, Tao; Li, Xue; Gong, Haimei

    2015-04-01

    Extended wavelength InGaAs photodiodes in 1.0~2.5μm spectral rang based on two types of material structures were investigated systematically. The first type InGaAs photodiode, marked by sample 1#, was fabricated using MOCVD epitaxial materials with P-i-N structure. The second type InGaAs photodiodes, marked by sample 2#, was fabricated using MBE epitaxial materials with P-i-N structure. The two types of photodiodes were fabricated by mesa etching technique, side-wall and surface passivation film. Dark current and voltage curves were measured by semiconductor parameters analyzer at different temperature, and dark current characteristics were analyzed using different perimeter to area method. The mechanism of the devices has been analysed. Polarization microscopy and conductive atomic force microscopy (c-AFM) have been used to investigate the local conductivity of the photodiodes' sensitive area. Combining the optical and c-AFM micrographs with dark current characteristics, we intended to characterize the relationships of the leak current and the defect. The results indicate that sample 1# has relative much more leak defects than that of sample 2#, and thus the dark current sample 1# is higher than that of sample 2# and. The defects are generated at the body of material and spread to the surface, and these defects cause very high dark current of sample 1#.

  5. Optimization of a HOT LWIR HgCdTe Photodiode for Fast Response and High Detectivity in Zero-Bias Operation Mode

    NASA Astrophysics Data System (ADS)

    Kopytko, M.; Kębłowski, A.; Madejczyk, P.; Martyniuk, P.; Piotrowski, J.; Gawron, W.; Grodecki, K.; Jóźwikowski, K.; Rutkowski, J.

    2017-10-01

    Fast response is an important property of infrared detectors for many applications. Currently, high-temperature long-wavelength infrared HgCdTe heterostructure photodiodes exhibit subnanosecond time constants while operating under reverse bias. However, nonequilibrium devices exhibit excessive low-frequency 1/ f noise that extends up to MHz range, representing a severe obstacle to their widespread application. Present efforts are focused on zero-bias operation of photodiodes. Unfortunately, the time constant of unbiased photodiodes is still at the level of several nanoseconds. We present herein a theoretical investigation of device design for improved response time and detectivity of long-wavelength infrared HgCdTe photodiodes operating at 230 K in zero-bias mode. The calculation results show that highly doped p-type HgCdTe is the absorber material of choice for fast photodiodes due to its high electron diffusion coefficient. The detectivity of such a device can also be optimized by using absorber doping of N A = 1 × 1017 cm-3. Reduction of the thickness is yet another approach to improve the device response. Time constant below 1 ns is achieved for an unbiased photodiode with absorber thickness below 4 μm. A tradeoff between the contradictory requirements of achieving high detectivity and fast response time is expected in an optically immersed photodiode with very small active area.

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

    PubMed

    Zelmer, Derek A; Campbell, Johnathon K

    2011-04-01

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

  7. A hybrid variational-ensemble data assimilation scheme with systematic error correction for limited-area ocean models

    NASA Astrophysics Data System (ADS)

    Oddo, Paolo; Storto, Andrea; Dobricic, Srdjan; Russo, Aniello; Lewis, Craig; Onken, Reiner; Coelho, Emanuel

    2016-10-01

    A hybrid variational-ensemble data assimilation scheme to estimate the vertical and horizontal parts of the background error covariance matrix for an ocean variational data assimilation system is presented and tested in a limited-area ocean model implemented in the western Mediterranean Sea. An extensive data set collected during the Recognized Environmental Picture Experiments conducted in June 2014 by the Centre for Maritime Research and Experimentation has been used for assimilation and validation. The hybrid scheme is used to both correct the systematic error introduced in the system from the external forcing (initialisation, lateral and surface open boundary conditions) and model parameterisation, and improve the representation of small-scale errors in the background error covariance matrix. An ensemble system is run offline for further use in the hybrid scheme, generated through perturbation of assimilated observations. Results of four different experiments have been compared. The reference experiment uses the classical stationary formulation of the background error covariance matrix and has no systematic error correction. The other three experiments account for, or not, systematic error correction and hybrid background error covariance matrix combining the static and the ensemble-derived errors of the day. Results show that the hybrid scheme when used in conjunction with the systematic error correction reduces the mean absolute error of temperature and salinity misfit by 55 and 42 % respectively, versus statistics arising from standard climatological covariances without systematic error correction.

  8. 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.

  9. Radon measurements with a PIN photodiode.

    PubMed

    Martín-Martín, A; Gutiérrez-Villanueva, J L; Muñoz, J M; García-Talavera, M; Adamiec, G; Iñiguez, M P

    2006-01-01

    Silicon photodiodes are well suited to detect alphas coming from different sources as neutron reactions or radon daughters. In this work a radon in air detecting device, using an 18x18 mm silicon PIN photodiode is studied. The ionized airborne decay products formed during radon diffusion were focused by an accelerating high voltage to the PIN surface. Several conducting rings were disposed inside a cylindrical PVC vessel in such a way that they reproduced the electric field created by a punctual charge located behind PIN position. Alpha spectra coming from the neutral and ionized species deposited on the PIN surface, dominated by 218Po and 214Po progeny peaks, were recorded for varying conditions. Those include radon concentration from a Pylon source, high voltage (thousands of volts) and PIN inverse bias voltage. Different parameters such as temperature and humidity were also registered during data acquisition. The increase in the particle collection efficiency with respect to zero electric field was compared with the corresponding to a parallel plates configuration. A discussion is made in terms of the most appropriate voltages for different radon concentrations.

  10. A high-speed lateral PIN polysilicon photodiode on standard bulk CMOS process

    NASA Astrophysics Data System (ADS)

    Zou, Wanghui; Xia, Yu; Chen, Diping; Zeng, Yun

    2017-03-01

    This paper reports a lateral PIN polysilicon photodiode on standard bulk complementary metal-oxidesemiconductor (CMOS) process for monolithically integrated high-speed optoelectronic integrated circuits (OEIC). A nominal undoped polysilicon as the photodetection area is intentionally created without introducing any process modification. With the device area of 50 × 50 μm2, a measured responsivity of 46 mA/W and a quantum efficiency of 11% were observed under the reverse voltage of 10 V and the wavelength of 520 nm. A compact equivalent circuit model for the proposed lateral photodiode is built to analyze the frequency response, and a bandwidth of over 20 GHz was obtained from the measured data, which is to the best of our knowledge the largest bandwidth ever reported based on standard bulk CMOS process.

  11. A Single-Chip Solar Energy Harvesting IC Using Integrated Photodiodes for Biomedical Implant Applications.

    PubMed

    Chen, Zhiyuan; Law, Man-Kay; Mak, Pui-In; Martins, Rui P

    2017-02-01

    In this paper, an ultra-compact single-chip solar energy harvesting IC using on-chip solar cell for biomedical implant applications is presented. By employing an on-chip charge pump with parallel connected photodiodes, a 3.5 × efficiency improvement can be achieved when compared with the conventional stacked photodiode approach to boost the harvested voltage while preserving a single-chip solution. A photodiode-assisted dual startup circuit (PDSC) is also proposed to improve the area efficiency and increase the startup speed by 77%. By employing an auxiliary charge pump (AQP) using zero threshold voltage (ZVT) devices in parallel with the main charge pump, a low startup voltage of 0.25 V is obtained while minimizing the reversion loss. A 4 Vin gate drive voltage is utilized to reduce the conduction loss. Systematic charge pump and solar cell area optimization is also introduced to improve the energy harvesting efficiency. The proposed system is implemented in a standard 0.18- [Formula: see text] CMOS technology and occupies an active area of 1.54 [Formula: see text]. Measurement results show that the on-chip charge pump can achieve a maximum efficiency of 67%. With an incident power of 1.22 [Formula: see text] from a halogen light source, the proposed energy harvesting IC can deliver an output power of 1.65 [Formula: see text] at 64% charge pump efficiency. The chip prototype is also verified using in-vitro experiment.

  12. Observation of 67 keV x-rays with a scintillation detector using proportional-mode silicon avalanche photodiode

    SciTech Connect

    Inoue, Keisuke; Kishimoto, Shunji

    2016-07-27

    We developed a scintillation X-ray detector using a proportional-mode silicon avalanche photodiode (Si-APD). We report a prototype detector using a lead-loaded plastic scintillator mounted on a proportional-mode Si-APD (active area size: 3 mm in diameter), which is operated at a low temperature. Using 67.41 keV X-rays, we could measure pulse-height spectra of scintillation light with a charge-sensitive preamplifier at 20, 0, and −35°C. Time spectra of the X-ray bunch structure were successfully recorded using a wideband and 60-dB-gain amplifier in hybrid-mode operation of the Photon Factory ring. We obtained a better time resolution of 0.51 ns (full width at half-maximum) for the single-bunch X-ray peak at −35°C. We were also able to observe a linear response of the scintillation pulses up to 8 Mcps for input photon rates up to 1.4 × 10{sup 8} photons/s.

  13. Photon counting techniques with silicon avalanche photodiodes.

    PubMed

    Dautet, H; Deschamps, P; Dion, B; Macgregor, A D; Macsween, D; McIntyre, R J; Trottier, C; Webb, P P

    1993-07-20

    The properties of avalanche photodiodes and associated electronics required for photon counting in the Geiger and the sub-Geiger modes are reviewed. When the Geiger mode is used, there are significant improvements reported in overall photon detection efficiencies (approaching 70% at 633 nm), and a timing jitter (under 200 ps) is achieved with passive quenching at high overvoltages (20-30 V). The results obtained by using an active-mode fast quench circuit capable of switching overvoltages as high as 15 V (giving photon detection efficiencies in the 50% range) with a dead time of less than 50 ns are reported. Larger diodes (up to 1 mm in diameter) that are usable in the Geiger mode and that have quantum efficiencies over 80% in the 500-800-nm range are also reported.

  14. Avalanche speed in thin avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Ong, D. S.; Rees, G. J.; David, J. P. R.

    2003-04-01

    The duration of the avalanche multiplication process in thin GaAs avalanche photodiodes is investigated using a full band Monte Carlo (FBMC) model. The results are compared with those of a simple random path length (RPL) model which makes the conventional assumptions of a displaced exponential for the ionization path length probability distribution function and that carriers always travel at their saturated drift velocities. We find that the avalanche duration calculated by the RPL model is almost twice of that predicted by the FBMC model, although the constant drift velocities used in the former model are estimated using the latter. The faster response predicted by FBMC model arises partly from the reduced dead space but mainly from the velocity overshoot of ionizing carriers. While the feedback multiplication processes forced by the effects of dead space extend the avalanche duration in short structures, the effects of velocity overshoot in the realistic model more than compensate, significantly improving multiplication bandwidth.

  15. 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.

  16. Internal quantum efficiency modeling of silicon photodiodes.

    PubMed

    Gentile, T R; Brown, S W; Lykke, K R; Shaw, P S; Woodward, J T

    2010-04-01

    Results are presented for modeling of the shape of the internal quantum efficiency (IQE) versus wavelength for silicon photodiodes in the 400 nm to 900 nm wavelength range. The IQE data are based on measurements of the external quantum efficiencies of three transmission optical trap detectors using an extensive set of laser wavelengths, along with the transmittance of the traps. We find that a simplified version of a previously reported IQE model fits the data with an accuracy of better than 0.01%. These results provide an important validation of the National Institute of Standards and Technology (NIST) spectral radiant power responsivity scale disseminated through the NIST Spectral Comparator Facility, as well as those scales disseminated by other National Metrology Institutes who have employed the same model.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  18. 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.

  19. 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.

  20. Initial characterization of a position-sensitive photodiode/BGO detector for PET (positron emission tomography)

    SciTech Connect

    Derenzo, S.E.; Moses, W.W.; Jackson, H.G.; Turko, B.T.; Cahoon, J.L.; Geyer, A.B.; Vuletich, T.

    1988-11-01

    We present initial results of a position-sensitive photodiode/BGO detector for high resolution, multi-layer positron emission tomography (PET). Position sensitivity is achieved by dividing the 3 mm /times/ 20 mm rectangular photosensitive area along the diagonal to form two triangular segments. Each segment was individually connected to a low-noise amplifier. The photodiodes and crystals were cooled to /minus/100/degree/C to reduce dark current and increase the BGO signal. With an amplifier peaking time of 17 ..mu..sec, the sum of the signals (511 keV photopeak) was 3200 electrons with a full width at half maximum (fwhm) of 750 electrons. The ratio of one signal to the sum determined the depth of interaction with a resolution of 11 mm fwhm. 27 refs., 7 figs.

  1. 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.

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

    PubMed

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

    2016-04-01

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

  3. 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.

  4. Functional hybrid systems based on large-area high-quality graphene.

    PubMed

    Coraux, Johann; Marty, Laëtitia; Bendiab, Nedjma; Bouchiat, Vincent

    2013-10-15

    The properties of sp² carbon allotropes can be tuned and enriched by their interaction with other materials. The large interface to the outside world in these forms of carbon is ideally suited for combining in an optimal manner several functionalities thanks to this interaction. A wide range of novel materials holding strong promise in energy, optoelectronics, microelectronics, mechanics, or medical applications have been designed accordingly. Graphene, the last representative of this family of sp² carbon materials, has already yielded a wealth of hybrid systems. A new class of these hybrids is emerging, which allows researchers to exploit the properties of truly single-layer graphene. These systems rely on high-quality graphene. In this Account, we describe our recent efforts to develop hybrid systems through various approaches and with various scopes. Depending on the interaction between graphene and molecules, metal clusters, layers, and substrates, either graphene may essentially preserve the electronic properties that make it a unique platform for electronic transport, or new organization and properties in the materials may arise due to the graphene contact at the expense of deep modification of graphene's properties. We prepare our graphene samples by both mechanical exfoliation of graphite and chemical vapor deposition on metals. We use this to study graphene in contact with various species, which either decorate graphene or are intercalated between it and its substrate. We first address the electronic and magnetic properties in systems where graphene is in epitaxy with a metal and discuss the potential to manipulate the properties of both materials, highlighting graphene's role as a protective capping layer in magnetic functional systems. We then present graphene/metal dot hybrids, which can utilize the two-dimensional gas properties of Dirac fermions in graphene. These hybrids allow one to tune the coupling between clusters hosting electronically ordered

  5. New silicon photodiodes for detection of the 1064nm wavelength radiation

    NASA Astrophysics Data System (ADS)

    Wegrzecki, Maciej; Piotrowski, Tadeusz; Puzewicz, Zbigniew; Bar, Jan; Czarnota, Ryszard; Dobrowolski, Rafal; Klimov, Andrii; Kulawik, Jan; Kłos, Helena; Marchewka, Michał; Nieprzecki, Marek; Panas, Andrzej; Seredyński, Bartłomiej; Sierakowski, Andrzej; Słysz, Wojciech; Synkiewicz, Beata; Szmigiel, Dariusz; Zaborowski, Michał

    2016-12-01

    In this paper a concept of a new bulk structure of p+-υ-n+ silicon photodiodes optimized for the detection of fast-changing radiation at the 1064 nm wavelength is presented. The design and technology for two types of quadrant photodiodes, the 8-segment photodiode and the 32-element linear photodiode array that were developed according to the concept are described. Electric and photoelectric parameters of the photodiodes mentioned above are presented.

  6. 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.

  7. A functional material based photodiode for solar tracking systems

    NASA Astrophysics Data System (ADS)

    Dere, A.; Tataroğlu, A.; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed A.; El-Tantawy, F. Farid; Farooq, W. A.; Yakuphanoglu, F.

    2017-09-01

    To prepare phosphotungstic acid (PTA) thin film was used drop-coating method. The film was dropped on p-Si having ohmic contact. The electrical and photovoltaic properties the fabricated Al/p-Si/phospotungstic acid(PTA)/Al photodiode were investigated. The current-voltage (I-V) measurements were carried out under dark and various illumination intensities. Under illumination, the photocurrent of the photodiode was found to be higher than the dark current. The prepared photodiode exhibited photovoltaic behavior. Also, the transient photocurrent measurement confirms that the photocurrent is sensitive to the illumination intensities. In addition, the capacitance/conductance-voltage (C/G-V) measurements were studied in the frequency range of 10 kHz to 1 MHz. The capacitance decreases with increasing frequency, suggesting a continuous distribution of interface states. As result, the prepared photodiode can be used in optoelectronic device applications.

  8. Irradiation stability of silicon photodiodes for extreme-ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Scholze, Frank; Klein, Roman; Bock, Thomas

    2003-10-01

    Photodiodes are used as easy-to-operate detectors in the extreme-ultraviolet spectral range. At the Physikalisch-Technische Bundesanstalt photodiodes are calibrated with an uncertainty of spectral responsivity of 0.3% or less. Stable photodiodes are a prerequisite for the dissemination of these high-accuracy calibrations to customers. Silicon photodiodes with different top layers were exposed to intense extreme-ultraviolet irradiation. Diodes coated with diamondlike carbon or TiSiN proved to be stable within a few percent up to a radiant exposure of 100 kJ/cm2. The changes in responsivity could be explained as being due to carbon contamination and to changes in the internal charge collection efficiency. In ultrahigh vacuum, no indication of oxidation was found.

  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. Radiation threshold levels for noise degradation of photodiodes. Technical report

    SciTech Connect

    Aukerman, L.W.; Vernon, F.L.; Song, Y.

    1986-09-30

    Space radiation can increase the noise of photodiodes as a result of either a sustained ionizing-dose-rate effect or displacement damage. Elementary, straightforward models are presented for calculating radiation threshold levels and rad hit susceptibility. Radiation-effects experiments that verify these models are discussed. Calculations for room-temperature silicon p-i-n photodetectors, an avalanche photodiode, and a hypothetical cooled staring detector indicate that this damage mechanism should not be ignored for space and nuclear environments.

  11. 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.

  12. Controlled-layer and large-area MoS2 films encapsulated Au nanoparticle hybrids for SERS.

    PubMed

    Li, Zhen; Jiang, Shouzhen; Huo, Yanyan; Liu, Mei; Yang, Cheng; Zhang, Chao; Liu, Xiaoyun; Sheng, Yingqing; Li, Chonghui; Man, Baoyuan

    2016-11-14

    In this work, a facile and effective method for controlled-layer and large-area MoS2 films encapsulated Au nanoparticle hybrids is developed. With accurate Ar plasma treatment time control, the large-area MoS2 layers can be obtained from monolayer to trilayer. The fabricated MoS2@Au NPs with higher surface area exhibit excellent Raman enhanced effect for aromatic organic molecules (rhodamine 6G and crystal violet) and achieve the best when the monolayer MoS2@AuNPs was obtained. The limit of detection is found to be as low as 1 × 10-10 M. The MoS2@AuNPs was characterized by SEM, EDS, AFM, Raman spectroscopy, UV-Vis, XRD and HRTEM.

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

    NASA Astrophysics Data System (ADS)

    Biedron, William S.

    1995-11-01

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

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

    SciTech Connect

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

    2014-01-20

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

  15. Dye based photodiodes for solar energy applications

    NASA Astrophysics Data System (ADS)

    Mensah-Darkwa, K.; Ocaya, R.; Dere, A.; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed A.; Soylu, M.; Gupta, R. K.; Yakuphanoglu, F.

    2017-10-01

    Coumarin (CO) doped methylene blue (MB) organic photo-devices were fabricated. The CO-doped MB (0.00, 0.01, 0.03, 0.05, 0.1 wt% CO) were coated onto the surface of a p-type Si substrate by drop casting method. Some electrical parameters of the devices have been examined by current-voltage ( I- V), capacitance-voltage ( C- V), and conductance-voltage ( G- V) measurements. The fabricated devices had excellent rectifying properties. The diode exhibits a non-ideal diode behavior due to the series resistance and interface layer. The ideality factor, the barrier height, and the series resistance values of the diode as a function of doping and light illumination have been estimated using modified Cheung-Cheung and Norde's method. The highest I photo/ I dark photosensitivity of 5606 was observed for the diode having 0.01 CO doping at 100 mW/cm2 under -3 V. Furthermore, change of capacitance and conductance measurements with frequency is related to the existence of interface states. A maximum power conversion efficiency of 2.4% is estimated for the fabricated devices. The results reveal that coumarin-doped methylene blue/ p-Si heterojunction can be used as a photodiode in optoelectronic applications. It is also usable in low-power photovoltaic applications.

  16. Quality assurance using a photodiode array.

    PubMed

    Balderson, M J; Spencer, D P; Nygren, I; Brown, D W

    2011-01-31

    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 the present paper, we describe the development of a novel device that enables precise and automated measurement of geometric parameters for the purpose of improving initial setup accuracy, and for standardizing repeated quality control activities. The device consists of a silicon photodiode array, an evaluation board, a data acquisition card, and a laptop. Measurements that demonstrate the utility of the device are also presented. Using the device, we show that the radiation light field congruence for both 6 and 15 MV beams is within 1.3 mm. The maximum measured disagreement between radiation field edges and light field edges was 1.290 ± 0.002 mm, while the smallest disagreement between the light field and radiation field edge was 0.016 ± 0.003 mm. Because measurements are automated, ambiguities resulting from interobserver variability are removed, greatly improving the reproducibility of measurements across observers. We expect the device to find use in consistency measurements on linear accelerators used for stereotactic radiosurgery, during the commissioning of new linear accelerators, or as an alternative to film or other commercially available devices for performing monthly or annual quality control checks.

  17. Simulation of infrared avalanche photodiodes from first principles

    NASA Astrophysics Data System (ADS)

    Storebø, Asta Katrine; Goldar, Dara; Brudevoll, Trond

    2017-02-01

    The present article deals with device physics and modeling of an Hg0.28Cd0.72Te wide-area electron-initiated avalanche photodiode, with main input data extracted from first principles electronic structure codes. Due to the large dimensions of 30 μm x 30 μm x 11 μm a method which combines Monte Carlo transport simulation in the active multiplication layer with `weak conduction' modeling in the charge carrier exit paths is introduced. Consequences resulting from adding perturbative, non-self-consistent small-signal analyses upon a self-consistent, large-signal background bias simulation are briefly examined. Likewise, the issue of ambipolar versus independent electron-hole transport in the absorption layer is discussed. We investigate the effects of alloy scattering on avalanche gain and compare alloy scattering rates used in some recent studies. Alloy scattering is for this particular device and model shown to increase the gain by more than an order of magnitude at typical bias voltages.

  18. A hybrid predictive model for acoustic noise in urban areas based on time series analysis and artificial neural network

    NASA Astrophysics Data System (ADS)

    Guarnaccia, Claudio; Quartieri, Joseph; Tepedino, Carmine

    2017-06-01

    The dangerous effect of noise on human health is well known. Both the auditory and non-auditory effects are largely documented in literature, and represent an important hazard in human activities. Particular care is devoted to road traffic noise, since it is growing according to the growth of residential, industrial and commercial areas. For these reasons, it is important to develop effective models able to predict the noise in a certain area. In this paper, a hybrid predictive model is presented. The model is based on the mixing of two different approach: the Time Series Analysis (TSA) and the Artificial Neural Network (ANN). The TSA model is based on the evaluation of trend and seasonality in the data, while the ANN model is based on the capacity of the network to "learn" the behavior of the data. The mixed approach will consist in the evaluation of noise levels by means of TSA and, once the differences (residuals) between TSA estimations and observed data have been calculated, in the training of a ANN on the residuals. This hybrid model will exploit interesting features and results, with a significant variation related to the number of steps forward in the prediction. It will be shown that the best results, in terms of prediction, are achieved predicting one step ahead in the future. Anyway, a 7 days prediction can be performed, with a slightly greater error, but offering a larger range of prediction, with respect to the single day ahead predictive model.

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

    NASA Astrophysics Data System (ADS)

    Kim, Woo Joo; Hwang, Sun Young

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

  20. Compact gamma-ray detection system for space applications based on photodiodes and CsI(TI) scintillation crystals

    NASA Astrophysics Data System (ADS)

    Graue, Roland; Stuffler, Timo; Goebel, Thomas

    1996-10-01

    For the measurement of astronomical gamma ray radiation in the energy range 50 keV to several MeV usually photomultiplier tubes (PMT) with scintillation crystals are used. However, due to the internal detection mechanism high voltage and single photon counting are required leading to heavy and structurally unpractical systems. Even APD's (avalanche photodiodes) do not circumvent the problem of the high voltage. Recent improvements in the performance of semiconductor detectors allow the use of large area and low noise pin photodiodes as innovative scintillation detectors with 40 - 100 V operating voltage only. Tl-doped CsI as scintillation crystal with a superior light yield has not only a much higher photon output compared to the light yield of pure CsI and BGO crystals which are used for the gamma ray detection with PMTs, but has also a perfect matching of spectral properties of the photodiode. This paper presents a comprehensive comparison with conventional PMT scintillation detector systems and the development activities of full size breadboards with such a photodiode/CsI(Tl) detector set-up. The relevant functional performance test results have shown the high technical maturity of this detector system and the principal feasibility for the application either in the INTEGRAL spectrometer and imager anticoincidence shield (ACS) or in image central detector system. The dedicated ACS configuration design featuring optimized mass budget combined with high gamma ray stopping efficiency is figured.

  1. Hybrid expert system for decision supporting in the medical area: complexity and cognitive computing.

    PubMed

    Brasil, L M; de Azevedo, F M; Barreto, J M

    2001-09-01

    This paper proposes a hybrid expert system (HES) to minimise some complexity problems pervasive to the artificial intelligence such as: the knowledge elicitation process, known as the bottleneck of expert systems; the model choice for knowledge representation to code human reasoning; the number of neurons in the hidden layer and the topology used in the connectionist approach; the difficulty to obtain the explanation on how the network arrived to a conclusion. Two algorithms applied to developing of HES are also suggested. One of them is used to train the fuzzy neural network and the other to obtain explanations on how the fuzzy neural network attained a conclusion. To overcome these difficulties the cognitive computing was integrated to the developed system. A case study is presented (e.g. epileptic crisis) with the problem definition and simulations. Results are also discussed.

  2. 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.

  3. 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.

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

    USGS Publications Warehouse

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

    1994-01-01

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

  5. Quantifying direct DQPSK receiver with integrated photodiode array by assessing an adapted common-mode rejection ratio

    NASA Astrophysics Data System (ADS)

    Wang, J.; Lauermann, M.; Zawadzki, C.; Brinker, W.; Zhang, Z.; de Felipe, D.; Keil, N.; Grote, N.; Schell, M.

    2011-12-01

    In this work, a direct DQPSK receiver was fabricated, which comprises a polymer waveguide based delay-line interferometer (DLI); a polymer based optical hybrid, and two monolithic pairs of > 25 GHz bandwidth photodiodes that are vertically coupled to the polymer planar lightwave circuit (PLC) via integrated 45° mirrors. The common mode rejection ratio (CMRR) is used to characterize the performance of coherent receivers, by indicating the electrical power balance between the balanced detectors. However, the standard CMRR can only be measured when the PDs can be illuminated separately. Also, the standard CMRR does not take into account the errors in the relative phases of the receiver outputs. We introduce an adapted CMRR to characterize the direct receiver, which takes into account the unequal responsivities of the PDs, the uneven split of the input power by the DLI and hybrid, the phase error and the extinction ratio of the DLI and hybrid.

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

    PubMed

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

    2012-12-01

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

  7. Single-wavelength-pump bi-directional hybrid fiber amplifier for bi-directional local area network application

    NASA Astrophysics Data System (ADS)

    Guo, Mars Ning; Liaw, Shien-Kuei; Shum, Perry Ping; Chen, Nan-Kuang; Hung, Hsin-Kai; Lin, Chinlon

    2011-01-01

    This paper proposes a novel bi-directional hybrid fiber amplifier using a single-wavelength pump laser diode (LD) at 1495 nm. The hybrid amplifier is theoretically applied in a 50 km bi-directional local area network (LAN) with 26 ch × 10 Gb/s for bi-directional transmission. Thirteen C-band channels serve as downlink signals while the other 13 L-band channels are employed as uplink signals. Without loss of generality, four channels (two from each band) are experimentally analyzed. Erbium doped fiber (EDF) provides amplification for the C-band channels and Raman amplification amplifies the L-band channels. The pump efficiency is improved by employing a double-pass scheme for both the Erbium doped fiber amplifier (EDFA) and Raman fiber amplifier (RFA). The chromatic dispersion incurred by all the channels is precisely compensated for by inserting a fiber Bragg grating (FBG) array in appropriate locations along the dispersion compensating fiber (DCF) segments. Moreover, gain equalization of all the channels is achieved by adjusting the FBG reflectivity. Both the simulation results and experimental measurements confirm the proposed device feasibility and potential application in a bi-directional LAN.

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

    PubMed Central

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

    2015-01-01

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

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

    SciTech Connect

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

    1999-02-01

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

  10. Dark current study for CMOS fully integrated-PIN-photodiodes

    NASA Astrophysics Data System (ADS)

    Teva, Jordi; Jessenig, Stefan; Jonak-Auer, Ingrid; Schrank, Franz; Wachmann, Ewald

    2011-05-01

    PIN photodiodes are semiconductor devices widely used in a huge range of applications, such as photoconductors, charge-coupled devices and pulse oximeters for medical applications. The possibility to combine and to integrate the fabrication of the sensor with its signal conditioning circuitry in a CMOS process allows device miniaturization in addition to enhance its properties lowering the production and assembly costs. This paper presents the design and characterization of silicon based PIN photodiodes integrated in a CMOS commercial process. A high-resistivity, low impurity substrate is chosen as the start material for the PIN photodiode array fabrication in order to fabricate devices with a minimum dark current. The dark current is studied, analyzed and measured for two different starting materials and for different geometries. A model previously proposed is reviewed and compared with experimental data.

  11. 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.

  12. Recent advances in telecommunication avalanche photodiodes with nano-sized multiplication region

    NASA Astrophysics Data System (ADS)

    Zhao, Yanli; Zhang, Shibo; He, Suxiang

    2015-11-01

    This paper reviews the recent advances in telecommunication avalanche photodiodes with nano-sized multiplication region. A new low noise avalanche photodiode based on InP traditional material has been proposed for high speed optical communication.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    PubMed

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

    2012-03-12

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

  15. 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.

  16. 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.

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

    SciTech Connect

    Budzyn, Grzegorz Podzorny, Tomasz

    2016-06-28

    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.

  18. Hybrid Text: An Engaging Genre to Teach Content Area Material across the Curriculum

    ERIC Educational Resources Information Center

    Bintz, William P.; Ciecierski, Lisa M.

    2017-01-01

    The Common Core State Standards for English language arts expect that teachers will use narrative and informational texts to teach content area material across the curriculum. However, many teachers at all grade levels struggle to incorporate both kinds of text, especially given the vast amount of specialized content they are required to teach.…

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

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

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

  20. High quantum efficiency GaP avalanche photodiodes.

    PubMed

    McIntosh, Dion; Zhou, Qiugui; Chen, Yaojia; Campbell, Joe C

    2011-09-26

    Gallium Phosphide (GaP) reach-through avalanche photodiodes (APDs) are reported. The APDs exhibited dark current less than a pico-ampere at unity gain. A quantum efficiency of 70% was achieved with a recessed window structure; this is almost two times higher than previous work. © 2011 Optical Society of America

  1. Photonic nanojet-enhanced nanometer-scale germanium photodiode.

    PubMed

    Hasan, Mehdi; Simpson, Jamesina J

    2013-08-01

    A design challenge for photodiodes yielding both high speed and responsivity is the necessity to concentrate incident light into a subwavelength active volume region. Photonic nanojets have been reported in the literature as a means to focus an incident plane wave to a subwavelength-waist propagating beam with applications ranging from next-generation DVDs to characterizing subwavelength features within dielectric targets. In the present work, a new application of photonic nanojets is proposed, focusing electromagnetic energy into a photodiode. Three-dimensional finite-difference time-domain solutions are conducted to determine the advantages of photonic nanojet-enhanced photodiodes at near-infrared wavelengths (1310 nm). We find that photonic nanojets provide a factor of 26 increase in the volume-integrated electric field within the subwavelength active volume of the photodiode of size 0.0045 μm³. Furthermore, this increase is achieved independent of the incident polarization and over a broad bandwidth. Photonic nanojets may thus serve as an attractive alternative to plasmonics for some applications.

  2. Radiation and Temperature Hard Multi-Pixel Avalanche Photodiodes

    NASA Technical Reports Server (NTRS)

    Bensaoula, Abdelhak (Inventor); Starikov, David (Inventor); Pillai, Rajeev (Inventor)

    2017-01-01

    The structure and method of fabricating a radiation and temperature hard avalanche photodiode with integrated radiation and temperature hard readout circuit, comprising a substrate, an avalanche region, an absorption region, and a plurality of Ohmic contacts are presented. The present disclosure provides for tuning of spectral sensitivity and high device efficiency, resulting in photon counting capability with decreased crosstalk and reduced dark current.

  3. 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.

  4. Reading a CD-ROM without a photodiode

    NASA Astrophysics Data System (ADS)

    Wishon, Michael J.; Mourozeau, G.; Ng, K.; Sahai, A. A.; Locquet, Alexandre; Citrin, D. S.

    2016-04-01

    We use a laser diode from a commercial CD/DVD-ROM drive to detect changes in the surface of a diffraction grating without a photodiode. Specifically, we exploit the changing terminal voltage in the laser-diode due to changing feedback strength as the laser is rastered across the grating's surface.

  5. BiCMOS-integrated photodiode exploiting drift enhancement

    NASA Astrophysics Data System (ADS)

    Swoboda, Robert; Schneider-Hornstein, Kerstin; Wille, Holger; Langguth, Gernot; Zimmermann, Horst

    2014-08-01

    A vertical pin photodiode with a thick intrinsic layer is integrated in a 0.5-μm BiCMOS process. The reverse bias of the photodiode can be increased far above the circuit supply voltage, enabling a high-drift velocity. Therefore, a highly efficient and very fast photodiode is achieved. Rise/fall times down to 94 ps/141 ps at a bias of 17 V were measured for a wavelength of 660 nm. The bandwidth was increased from 1.1 GHz at 3 V to 2.9 GHz at 17 V due to the drift enhancement. A quantum efficiency of 85% with a 660-nm light was verified. The technological measures to avoid negative effects on an NPN transistor due to the Kirk effect caused by the low-doped I-layer epitaxy are described. With a high-energy collector implant, the NPN transit frequency is held above 20 GHz. CMOS devices are unaffected. This photodiode is suitable for a wide variety of high-sensitivity optical sensor applications, for optical communications, for fiber-in-the-home applications, and for optical interconnects.

  6. Traveling wave model of uni-traveling carrier photodiode

    NASA Astrophysics Data System (ADS)

    Khanra, Senjuti; Das Barman, Abhirup

    2015-06-01

    A traveling wave time domain model of bulk InGaAs/InP uni-traveling carrier photodiode is presented in terms of integral carrier density rate equation. The wavelength dependent responsivity at different absorption width has been derived from quantum mechanical principle. Output photocurrent response with time is found in close agreement with the experimental value.

  7. Influence of Be doping placement in InAs/GaSb superlattice-based absorber on the performance of MWIR photodiodes

    NASA Astrophysics Data System (ADS)

    Czuba, K.; Sankowska, I.; Jureńczyk, J.; Jasik, A.; Papis-Polakowska, E.; Kaniewski, J.

    2017-05-01

    Doping of the absorption region is one of the most crucial aspects in the narrow-bandgap semiconductor design of a photodiode, especially if it is adjacent to the p-n junction area. It has a significant impact on various dark current mechanisms, and thus the overall performance of these devices. In this work, the influence of Be doping placement in the absorption region of type-II InAs/GaSb superlattice-based homojunction photodiodes on their performance was investigated. The analysis of diffusion, generation-recombination, shunt and the tunnelling components of the dark current was performed over a wide range of temperatures. Moreover, performance-limiting factors were considered as well as their impact on the most important figures of merit of the photodetectors. The photodiodes with Be-doped InAs layers in the absorption region achieved the best performance.

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

    PubMed Central

    2011-01-01

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

  9. New integration concept of PIN photodiodes in 0.35μm CMOS technologies

    NASA Astrophysics Data System (ADS)

    Jonak-Auer, I.; Teva, J.; Park, J. M.; Jessenig, S.; Rohrbacher, M.; Wachmann, E.

    2012-06-01

    We report on a new and very cost effective way to integrate PIN photo detectors into a standard CMOS process. Starting with lowly p-doped (intrinsic) EPI we need just one additional mask and ion implantation in order to provide doping concentrations very similar to standard CMOS substrates to areas outside the photoactive regions. Thus full functionality of the standard CMOS logic can be guaranteed while the photo detectors highly benefit from the low doping concentrations of the intrinsic EPI. The major advantage of this integration concept is that complete modularity of the CMOS process remains untouched by the implementation of PIN photodiodes. Functionality of the implanted region as host of logic components was confirmed by electrical measurements of relevant standard transistor as well as ESD protection devices. We also succeeded in establishing an EPI deposition process in austriamicrosystems 200mm wafer fabrication which guarantees the formation of very lowly p-doped intrinsic layers, which major semiconductor vendors could not provide. With our EPI deposition process we acquire doping levels as low as 1•1012/cm3. In order to maintain those doping levels during CMOS processing we employed special surface protection techniques. After complete CMOS processing doping concentrations were about 4•1013/cm3 at the EPI surface while the bulk EPI kept its original low doping concentrations. Photodiode parameters could further be improved by bottom antireflective coatings and a special implant to reduce dark currents. For 100×100μm2 photodiodes in 20μm thick intrinsic EPI on highly p-doped substrates we achieved responsivities of 0.57A/W at λ=675nm, capacitances of 0.066pF and dark currents of 0.8pA at 2V reverse voltage.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

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

  12. Hybridization, natural selection, and evolution of reproductive isolation: a 25-years survey of an artificial sympatric area between two mosquito sibling species of the Aedes mariae complex.

    PubMed

    Urbanelli, Sandra; Porretta, Daniele; Mastrantonio, Valentina; Bellini, Romeo; Pieraccini, Giuseppe; Romoli, Riccardo; Crasta, Graziano; Nascetti, Giuseppe

    2014-10-01

    Natural selection can act against maladaptive hybridization between co-occurring divergent populations leading to evolution of reproductive isolation among them. A critical unanswered question about this process that provides a basis for the theory of speciation by reinforcement, is whether natural selection can cause hybridization rates to evolve to zero. Here, we investigated this issue in two sibling mosquitoes species, Aedes mariae and Aedes zammitii, that show postmating reproductive isolation (F1 males sterile) and partial premating isolation (different height of mating swarms) that could be reinforced by natural selection against hybridization. In 1986, we created an artificial sympatric area between the two species and sampled about 20,000 individuals over the following 25 years. Between 1986 and 2011, the composition of mating swarms and the hybridization rate between the two species were investigated across time in the sympatric area. Our results showed that A. mariae and A. zammitii have not completed reproductive isolation since their first contact in the artificial sympatric area. We have discussed the relative role of factors such as time of contact, gene flow, strength of natural selection, and biological mechanisms causing prezygotic isolation to explain the observed results.

  13. Single-photon detection beyond 1 µm: performance of commercially available germanium photodiodes.

    PubMed

    Lacaita, A; Francese, P A; Zappa, F; Cova, S

    1994-10-20

    Germanium avalanche photodiodes (APD's) working biased above the breakdown voltage detect single optical photons in the near-infrared wavelength range. We give guidelines for the selection of devices suitable for photon-counting applications among the commercial samples, and we discuss in detail how the devices should be operated to achieve the best performance, both in terms of noise-equivalent power (NEP) and the timing-equivalent bandwidth. We introduce the driving electronics and we show that, in the measurements of fast optical signals, the adoption of single-photon techniques is very favorable, notwithstanding that presently available photodiodes are not designed for this purpose. On the contrary, in the detection of cw signals, the lower NEP values achieved in photon counting may not be sufficient to justify the replacement of conventional analog p-i-n germanium detectors, which offer comparable performance with a definitely larger sensitive area. Finally, we show that, by properly choosing theoperating conditions, some selected APD's achieve an 85-ps time resolution in the detection of optical photons at a 1.3-µm wavelength, which corresponds to a timing-equivalent bandwidth of 1.8 GHz. To the best of our knowledge, this time resolution is the lowest reported to date for single-photon detectors in the near infrared.

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

    SciTech Connect

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

    1994-10-01

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

  15. Design, fabrication and physical analysis of TiN/AlN deep UV photodiodes

    NASA Astrophysics Data System (ADS)

    Barkad, H. A.; Soltani, A.; Mattalah, M.; Gerbedoen, J.-C.; Rousseau, M.; De Jaeger, J.-C.; BenMoussa, A.; Mortet, V.; Haenen, K.; Benbakhti, B.; Moreau, M.; Dupuis, R.; Ougazzaden, A.

    2010-11-01

    Deep-ultraviolet solar-blind photodiodes based on high-quality AlN films grown on sapphire substrates with a metal-semiconductor-metal configuration were simulated and fabricated. The Schottky contact is based on TiN metallization. The material is characterized by the micro-Raman spectroscopy and x-ray diffraction technique. The detector presents an extremely low dark current of 100 fA at -100 V dc bias for large device area as high as 3.1 mm2. It also exhibits a rejection ratio between 180 and 300 nm of three orders of magnitude with a very sharp cut-off wavelength at 203 nm (~6.1 eV). The simulation to optimize the photodiode topology is based on a 2D energy-balance model using the COMSOL® software. Simulation performed for different spacing for a given bias between electrodes show that a compromise must be found between the dark current and the responsivity for the optimization of the device performance. The measurement results are in good agreement with the model predictions.

  16. 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

  17. Enzyme-mimetic catalyst-modified nanoporous SiO2-cellulose hybrid composites with high specific surface area for rapid H2O2 detection.

    PubMed

    Jiang, Yijun; Wang, Wei; Li, Xiutao; Wang, Xicheng; Zhou, Jianwei; Mu, Xindong

    2013-03-01

    Mesoporous silica-cellulose hybrid composites were prepared by surface sol-gel coating process on nature cellulose substance. The template CTAB (hexadecyl trimethyl ammonium Bromide) in the silica film can be removed by extraction to obtain high specific surface area (80.7 m(2) g(-1)), which is 2 orders of magnitude higher than that of raw cellulose. In the following, the enzyme-mimetic catalyst and chromogenic agent were introduced onto the hybrid system. Just as the peroxidase, the resultant hybrid material exhibits extraordinary sensitivity for the H2O2 and shows an immediate and obvious color change. The detection limit is about 1 μmol L(-1) by the naked eye.

  18. Hydrodynamic rupture of liver in combat patient: a case of successful application of "damage control" tactic in area of the hybrid war in East Ukraine.

    PubMed

    Khomenko, Igor; Shapovalov, Vitalii; Tsema, Ievgen; Makarov, Georgii; Palytsia, Roman; Zavodovskyi, Ievgen; Ishchenko, Ivan; Dinets, Andrii; Mishalov, Vladimir

    2017-08-15

    The hybrid war of Russia against Ukraine has been started in certain districts of Donetsk and Luhansk oblasts within the Donbas area in 2014. We report a clinical case of a combat patient who was injured after the multiple launcher rocket system "Grad" shelling, diagnosed with hydrodynamic liver rupture followed by medical management with application of damage control (DC) tactic in conditions of hybrid war. The patient underwent relaparatomy, liver resection, endoscopic papillosphincterotomy, endoscopic retrograde cholecystopancreatography, stenting of the common bile duct, and VAC-therapy. Applied treatment modalities were effective; the patient was discharged on the 49th day after injury. To our best knowledge, this is the first report describing a successful application of DC tactic in the hybrid war in East Ukraine. From this case, we suggest that application of DC tactic at all levels of combat medical care could save more lives.

  19. 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.

  20. 10 Gbps silicon waveguide-integrated infrared avalanche photodiode.

    PubMed

    Ackert, Jason J; Karar, Abdullah S; Paez, Dixon J; Jessop, Paul E; Cartledge, John C; Knights, Andrew P

    2013-08-26

    We have fabricated monolithic silicon avalanche photodiodes capable of 10 Gbps operation at a wavelength of 1550 nm. The photodiodes are entirely CMOS process compatible and comprise a p-i-n junction integrated with a silicon-on-insulator (SOI) rib waveguide. Photo-generation is initiated via the presence of deep levels in the silicon bandgap, introduced by ion implantation and modified by subsequent annealing. The devices show a small signal 3 dB bandwidth of 2.0 GHz as well as an open eye pattern at 10 Gbps. A responsivity of 4.7 ± 0.5 A/W is measured for a 600 µm device at a reverse bias of 40 V.

  1. Planar InAs photodiodes fabricated using He ion implantation.

    PubMed

    Sandall, Ian; Tan, Chee Hing; Smith, Andrew; Gwilliam, Russell

    2012-04-09

    We have performed Helium (He) ion implantation on InAs and performed post implant annealing to investigate the effect on the sheet resistance. Using the transmission line model (TLM) we have shown that the sheet resistance of a p⁺ InAs layer, with a nominal doping concentration of 1x10¹⁸ cm⁻³, can increase by over 5 orders of magnitude upon implantation. We achieved a sheet resistance of 1x10⁵ Ω/Square in an 'as-implanted' sample and with subsequent annealing this can be further increased to 1x10⁷ Ω/Square. By also performing implantation on p-i-n structures we have shown that it is possible to produce planar photodiodes with comparable dark currents and quantum efficiencies to chemically etched reference mesa InAs photodiodes.

  2. 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.

  3. 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

  4. Heteroleptic neutral Ru(II) complexes based photodiodes

    NASA Astrophysics Data System (ADS)

    Elgazzar, Elsayed; Dayan, O.; Serbetci, Z.; Dere, A.; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed A.; El-Tantawy, Farid; Farooq, W. A.; Yakuphanoglu, F.

    2017-07-01

    The two complexes Ru (II) containing 2,6-bis(benzimidazol-2-yl)pyridine and 2-pyridine and 2-quinoline carboxylates were synthesized to fabricate organic photodiodes. The electrical properties of Au / Ru (II) complex (I) / n - Si / Al and Au / Ru (II) complex (II) / n - Si / Al diodes were investigated by current-voltage and capacitance-voltage measurements. The fabricated devices give a high rectification behavior with rectification ratio of 2.4 × 104 -2.1 × 103 at ± 4 V. The diodes exhibited a high photoconductivity based on trap levels within band gap. The series resistance and barrier height were calculated from (C - V) measurements and compared to other of (I - V) . The obtained results indicate that the prepared photodiodes can be used as photosensor for optoelectronic applications.

  5. 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

  6. Flexible germanium nanomembrane metal-semiconductor-metal photodiodes

    SciTech Connect

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

    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/cm{sup 2} 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.

  7. Surface plasmon resonance imaging biosensor based on silicon photodiode array

    NASA Astrophysics Data System (ADS)

    Yin, Shaoyun; Sun, Xiuhui; Deng, Qiling; Xia, Liangping; Du, Chunlei

    2010-11-01

    The detection limit of surface plasmon resonance imaging (SPRI) biosensor is constrained in part by the SPR biochip and in part by the resolution of the optical intensity of detecting instruments. In this paper, silicon photodiode is proposed as the optical intensity detecting element instead of the traditionally used charge coupled device (CCD), combining with high resolution analog/digital converter, this method can efficiently reduce the cost and increase the sensitivity of the SPRI system while keeping its virtue of multiple channels real time detecting. Based on this method, An SPRI experimental system with two channels is designed and the optical intensity of each channel is detected by a photodiode. By carrying out testing experiments using sucrose solution with different concentrations (corresponding to different refractive index), the system sensitivity of 10-6 refractive index unit (RIU) is obtained.

  8. Design, fabrication, and characterization of InSb avalanche photodiode

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    In this communication, the potentiality of InSb material as an avalanche photodiode (APD) device is investigated. Current density-voltage (J-V) characteristics at 77K of InSb pin photodiodes were simulated by using ATLAS software from SILVACO, in dark conditions and under illumination. In order to validate parameter values used for the modeling, theoretical J-V results were compared with experimental measurements performed on InSb diodes fabricated by molecular beam epitaxy. Next, assuming a multiplication process only induced by the electrons (e-APD), different designs of separate absorption and multiplication (SAM) APD structure were theoretically investigated and the first InSb SAM APD structure with 1μm thick multiplication layer was then fabricated and characterized.

  9. Locating hybrid individuals in the red wolf (Canis rufus) experimental population area using a spatially targeted sampling strategy and faecal DNA genotyping.

    PubMed

    Adams, Jennifer R; Lucash, Chris; Schutte, Leslie; Waits, Lisette P

    2007-05-01

    Hybridization with coyotes (Canis latrans) continues to threaten the recovery of endangered red wolves (Canis rufus) in North Carolina and requires the development of new strategies to detect and remove coyotes and hybrids. Here, we combine a spatially targeted faecal collection strategy with a previously published reference genotype data filtering method and a genetic test for coyote ancestry to screen portions of the red wolf experimental population area for the presence of nonred wolf canids. We also test the accuracy of our maximum-likelihood assignment test for identifying hybrid individuals using eight microsatellite loci instead of the original 18 loci and compare its performance to the Bayesian approach implemented in newhybrids. We obtained faecal DNA genotypes for 89 samples, 73 of which were matched to 23 known individuals. The performance of two sampling strategies - comprehensive sweep and opportunistic spot-check was evaluated. The opportunistic spot-check sampling strategy required less effort than the comprehensive sweep sampling strategy but identified fewer individuals. Six hybrids or coyotes were detected and five of these individuals were subsequently captured and removed from the population. The accuracy and power of the genetic test for coyote ancestry is decreased when using eight loci; however, nonred wolf canids are identified with high frequency. This combination of molecular and traditional field-based approaches has great potential for addressing the challenge of hybridization in other species and ecosystems.

  10. 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.

  11. III-Nitride Visible- and Solar-Blind Avalanche Photodiodes

    DTIC Science & Technology

    2007-12-01

    Manager: Dr. Donald Silversmith – Air Force Office of Scientific Research Principal Investigator: Professor Manijeh Razeghi Center for...photodiodes K. Minder, J.L. Pau, R. McClintock, P. Kung, C. Bayram, M. Razeghi and D. Silversmith Applied Physics Letters, Vol. 91, No. 7, p. 073513-1...M. Razeghi, E. Muñoz, and D. Silversmith Applied Physics Letters, Vol. 91, No. 04, p. 041104 -1-- July 23, 2007 3. Hole-initiated multiplication

  12. Wavelength dependence of silicon avalanche photodiode fabricated by CMOS process

    NASA Astrophysics Data System (ADS)

    Mohammed Napiah, Zul Atfyi Fauzan; Hishiki, Takuya; Iiyama, Koichi

    2017-07-01

    Avalanche photodiodes fabricated by CMOS process (CMOS-APDs) have features of high avalanche gain below 10 V, wide bandwidth over 5 GHz, and easy integration with electronic circuits. In CMOS-APDs, guard ring structure is introduced for high-speed operation by canceling photo-generated carriers in the substrate at the sacrifice of the responsivity. We describe here wavelength dependence of the responsivity and the bandwidth of the CMOS-APDs with shorted and opened guard ring structure.

  13. 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.

  14. 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.

  15. 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.

  16. Automated Sky-Compensating Photometer with a Silicon Photodiode

    NASA Astrophysics Data System (ADS)

    Riggs, J. D.; Alexander, D. R.

    1983-12-01

    This article describes the automated, sky-compensating filter photometer, currently being built and tested for the Lake Afton Public Observatory (LAPO) at Wichita State University, for use on the 16-inch Ritchey-Chretien telescope. Design emphasis is directed toward minimal user intervention due to varying user backgrounds. The instrumentation consists of a sky-compensating photometer, a Hamamatsu S1133-01 silicon photodiode detector, a programmable DC amplifier, and a computer dedicated to data collection and photometer control.

  17. Design and fabrication of dioxyphenylcoumarin substituted cyclotriphosphazene compounds photodiodes

    NASA Astrophysics Data System (ADS)

    Elgazzar, Elsayed; Dere, A.; Özen, Furkan; Koran, Kenan; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed A.; Orhan Görgülü, Ahmet; El-Tantawy, F.; Yakuphanoglu, F.

    2017-06-01

    The present study introduces cyclotriphosphazene compounds substituted by dioxyphenylcoumarin as a photodiode application. Firstly, 7,8-dihydroxy-3-(3-methylphenyl)coumarin (1b) has been obtained by conventional as well as microwave assisted methods. Novel optoelectronic device characteristics for both mono and disubstituted dioxyphenylcoumarin bearing cyclotriphosphazene compounds (HCP-2 and HCP-4) have been synthesized from the reactions of cyclotriphosphazene containing dioxybiphenyl (HCP-1 and HCP-3) with compound 1b, respectively. The structures of compounds HCP 1-4 were identified by using elemental analysis, 1H, 13C-APT, 31P NMR and 2D HETCOR NMR and FT-IR spectroscopy methods. The Al/HCP-2/p-Si/Al and Al/HCP-4/-p-Si/Al photodiodes properties have been investigated from current-voltage (I - V) and capacitance-voltage (C - V) measurements. The electrical parameters of the prepared diodes such as ideality factor n and series resistance Rs were investigated in dark and at room temperature from (I - V) curve and Nord's method. As can be seen, the Al/HCP-2/p-Si/Al diode of high rectification ratio RR and with ideality factor greater than unity. The influence of light illuminations on the diode shows that the device can be used as photodiode with good efficiency. The barrier height ϕb and series resistance Rs have been calculated from the capacitance-voltage (C - V) and conductance-voltage (G - V) measurements under various applied frequencies from 10 kHz to 1 MHz. the high difference in the results of barrier height obtained from I-V and C-V calculations confirm the influence of series resistance and localized states on transport of charge carriers and the photodiode performance.

  18. 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.

  19. Investigation of avalanche photodiodes radiation hardness for baryonic matter studies

    NASA Astrophysics Data System (ADS)

    Kushpil, V.; Mikhaylov, V.; Ladygin, V. P.; Kugler, A.; Kushpil, S.; Svoboda, O.; Tlustý, P.

    2016-01-01

    Modern avalanche photodiodes (APDs) with high gain are good device candidates for light readout from detectors applied in relativistic heavy ion collisions experiments. The results of the investigations of the APDs properties from Zecotek, Ketek and Hamamatsu manufacturers after irradiation using secondary neutrons from cyclotron facility U120M at NPI of ASCR in Řež are presented. The results of the investigations can be used for the design of the detectors for the experiments at NICA and FAIR.

  20. Avalanche photodiode based detector for beam emission spectroscopy.

    PubMed

    Dunai, D; Zoletnik, S; Sárközi, J; Field, A R

    2010-10-01

    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 (≈10(8)-10(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).

  1. Vertically illuminated TW-UTC photodiodes for terahertz generation

    NASA Astrophysics Data System (ADS)

    Barrientos Z., Claudio M.; Calle G., Victor H.; Alvarez, Jaime A.; Mena, F. Patricio; Vukusic, Josip; Stake, Jan; Michael, Ernest A.

    2012-09-01

    More efficient and powerful continuous-wave photonic mixers as terahertz sources are motivated by the need of more versatile local oscillators for submillimeter/terahertz receiver systems. Uni-Travelling Carrier (UTC) photodiodes are very prospective candidates for reaching this objective, but so far only have been reported as lumped-elements or as edge-illuminated optical-waveguide travelling-wave (TW) devices. To overcome the associated power limitations of those implementations, we are developing a novel implementation of the UTC photodiodes which combines a travelingwave photomixer with vertical velocity-matched illumination in a distributed structure. In this implementation called velocity-matched travelling-wave uni-travelling carrier photodiode, it is possible to obtain in-situ velocity matching of the beat-fringes of the two angled laser beams with the submm/THz-wave on the stripline. In this way, minimum frequency roll-off is achieved by tuning the angle between the two laser beams. A first design of these TW-UTC PDs from our Terahertz Photonics Laboratory at University of Chile has been micro-fabricated at the MC2 cleanroom facility at Chalmers Technical University.

  2. 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

  3. U.S. EPA honors San Francisco Bay Area firm Hybrid Coating Technologies with Green Chemistry Award

    EPA Pesticide Factsheets

    SAN FRANCISCO - Today the U.S. Environmental Protection Agency recognized Hybrid Coating Technologies of Daly City, Calif. with a Presidential Green Chemistry Award for developing a safer, plant-based polyurethane for use on floors, furniture and in

  4. Pulsed irradiation of optimized, MBE grown, AlGaAs/GaAs radiation hardened photodiodes. Rev

    SciTech Connect

    Wiczer, J.J.; Fischer, T.A.; Dawson, L.R.; Osbourn, G.C.; Zipperian, T.E.; Barnes, C.E.

    1984-01-01

    An AlGaAs/GaAs double heterojunction, mesa isolated, photodiode grown by molecular beam epitaxy was irradiated with 18 MeV electrons, 1 to 10 MeV x-rays, and neutrons from a pulsed reactor. Test results indicate that the AlGaAs/GaAs photodiodes generate approximately 10 to 20 times less photocurrent during exposure to a pulse of ionizing-radiation than radiation hardened silicon PIN photodiodes. Studies of neutron induced permanent damage in the AlGaAs/GaAs photodiode show only small changes in optical responsivity and a factor of 8 increase in leakage currents after exposure to 3.6 x 10/sup 15/ neutrons/cm/sup 2/ and 900 krad gamma. The silicon PIN photodiode was exposed to only 28% of the fluence used on the AlGaAs photodiodes and we observed a 40% decrease in optical responsivity and a factor of 7000 increase in leakage current.

  5. Nonlinear Time-Variant Response in an Avalanche Photodiode Array Based Laser Detection and Ranging System

    DTIC Science & Technology

    2007-03-01

    Nonlinear Time-Variant Response in an Avalanche Photodiode Array Based Laser Detection and Ranging System THESIS Michael D. Seal, Captain, USAF AFIT...DISTRIBUTION UNLIMITED. AFIT/GEO/ENG/07-03 Nonlinear Time-Variant Response in an Avalanche Photodiode Array Based Laser Detection and Ranging System...time-variant behavior exhibited by an avalanche photodiode (APD) array based laser ranging and detec- tion (LADAR) system. This examination was

  6. Low-cost, High Performance Avalanche Photodiodes for Enabling High Sensitivity Bio-fluorescence Detection

    DTIC Science & Technology

    2012-04-01

    Detection Efficiency Avalanche Photodiode in Geiger - mode Operation. IEEE Phot. Tech. Lett. 2007, 19, 378–80. 5. Vurgaftman, I.; Meyer, J. R. Band...Low-cost, High Performance Avalanche Photodiodes for Enabling High Sensitivity Bio-fluorescence Detection (Final Report) by Anand V. Sampath...Research Laboratory Adelphi, MD 20783-1197 ARL-TR-5981 April 2012 Low-cost, High Performance Avalanche Photodiodes for Enabling High

  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. Guided-wave photodiode using through-absorber quantum-well-intermixing and methods thereof

    SciTech Connect

    Skogen, Erik J.

    2016-10-25

    The present invention includes a high-speed, high-saturation power detector (e.g., a photodiode) compatible with a relatively simple monolithic integration process. In particular embodiments, the photodiode includes an intrinsic bulk absorption region, which is grown above a main waveguide core including a number of quantum wells (QWs) that are used as the active region of a phase modulator. The invention also includes methods of fabricating integrated photodiode and waveguide assemblies using a monolithic, simplified process.

  9. 3D integration of Geiger-mode avalanche photodiodes aimed to very high fill-factor pixels for future linear colliders

    NASA Astrophysics Data System (ADS)

    Vilella, E.; Alonso, O.; Diéguez, A.

    2013-12-01

    This paper presents an analysis of the maximum achievable fill-factor by a pixel detector of Geiger-mode avalanche photodiodes with the Chartered 130 nm/Tezzaron 3D process. The analysis shows that fill-factors between 66% and 96% can be obtained with different array architectures and a time-gated readout circuit of minimum area. The maximum fill-factor is achieved when the two-layer vertical stack is used to overlap the non-sensitive areas of one layer with the sensitive areas of the other one. Moreover, different sensor areas are used to further increase the fill-factor. A chip containing a pixel detector of the Geiger-mode avalanche photodiodes and aimed to future linear colliders has been designed with the Chartered 130 nm/Tezzaron 3D process to increase the fill-factor.

  10. Electrodynamics of a planar photodiode discharge for an obliquely incident initiating laser pulse

    SciTech Connect

    Lazarev, Y. N. Syrtsova, Yu. G.

    2012-01-15

    An approximate analytic solution of Maxwell's equations is obtained inside a photodiode. Analysis of this solution shows that the earlier discovered significant decrease in the radiation field characteristics over an anode is caused by a considerable increase in the amplitude of a wave generated inside the photodiode, which for angles of incidence {theta} {yields} {pi}/2 achieves a value comparable to the initial electric field strength applied to the photodiode. In this case, the electromagnetic energy flux density inside the photodiode exceeds tens times or more the electromagnetic energy flux density over the anode. The results of numerical calculations confirm the analytic results.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  12. Conceptual Design of Large Surface Area Porous Polymeric Hybrid Media Based on Polyhedral Oligomeric Silsesquioxane Precursors: Preparation, Tailoring of Porous Properties, and Internal Surface Functionalization

    PubMed Central

    2013-01-01

    We report on the preparation of hybrid, organic–inorganic porous materials derived from polyhedral oligomeric vinylsilsesquioxanes (vinylPOSS) via a single-step molding process. The monolithic, large surface area materials are studied with a particular focus on morphology and porous properties. Radical vinyl polymerization of the nanometer-sized POSS building blocks is therefore utilized via a thermally initiated route and in porogenic diluents such as tetrahydrofuran and polyethylene glycols of varying composition. Careful choice of these porogenic solvents and proper choice of initiator concentration lead to highly porous monolithic building entities which show a rigid, 3D-adhered, porous structure, macroscopically adapting the shape of a given mold. The described materials reflect Brunauer–Emmett–Teller (BET) surface areas of 700 m2/g or more and maximum tunable mesopore volumes of up to 2 cm3/g. Experimental investigations demonstrate the option to tailor nanoporosity and macroporosity in the single-step free-radical polymerization process. While studies on the influence of the used porogenic solvents reveal tuneability of pore sizes due to the unique pore formation process, tailored existence of residual vinyl groups allows facile postpolymerization modification of the highly porous, large surface area hybrid materials exploited via thiol–ene “click” chemistry. Our developed, simply realizable preparation process explores a new route to derive porous organic–inorganic hybrid adsorbents for a wide variety of applications such as extraction, separation science, and catalysis. PMID:23489022

  13. Load Frequency Control of a Two-Area Thermal-Hybrid Power System Using a Novel Quasi-Opposition Harmony Search Algorithm

    NASA Astrophysics Data System (ADS)

    Mahto, Tarkeshwar; Mukherjee, V.

    2016-09-01

    In the present work, a two-area thermal-hybrid interconnected power system, consisting of a thermal unit in one area and a hybrid wind-diesel unit in other area is considered. Capacitive energy storage (CES) and CES with static synchronous series compensator (SSSC) are connected to the studied two-area model to compensate for varying load demand, intermittent output power and area frequency oscillation. A novel quasi-opposition harmony search (QOHS) algorithm is proposed and applied to tune the various tunable parameters of the studied power system model. Simulation study reveals that inclusion of CES unit in both the areas yields superb damping performance for frequency and tie-line power deviation. From the simulation results it is further revealed that inclusion of SSSC is not viable from both technical as well as economical point of view as no considerable improvement in transient performance is noted with its inclusion in the tie-line of the studied power system model. The results presented in this paper demonstrate the potential of the proposed QOHS algorithm and show its effectiveness and robustness for solving frequency and power drift problems of the studied power systems. Binary coded genetic algorithm is taken for sake of comparison.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  15. 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.

  16. Micro-diffraction Investigation of Localized Strain in Mesa-etched HgCdTe Photodiodes

    NASA Astrophysics Data System (ADS)

    Tuaz, Aymeric; Ballet, Philippe; Biquard, Xavier; Rieutord, François

    2017-09-01

    We present an x-ray micro-diffraction investigation of localized strain and lattice disorientation in HgCdTe layers with a submicronic resolution using a synchrotron white beam in Laue configuration. Diffraction peak displacement mapping evidences bending of the crystal planes around mesa-etched photodiodes, with strong dependence upon the processing steps. The etching step by itself does not induce any deformation within the layer, while the passivation step leads to sufficient strain for plastic deformation to occur at the lateral edges of the etching. The annealing step is found to have a healing effect on the layer, which reduces the overall deformation and even re-crystallizes plastically deformed areas of the layer.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. 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.

  19. InAlAs/InGaAs avalanche photodiode arrays for free space optical communication.

    PubMed

    Ferraro, Mike S; Clark, William R; Rabinovich, William S; Mahon, Rita; Murphy, James L; Goetz, Peter G; Thomas, Linda M; Burris, Harris R; Moore, Christopher I; Waters, William D; Vaccaro, Kenneth; Krejca, Brian D

    2015-11-01

    In free space optical communication, photodetectors serve not only as communications receivers but also as position sensitive detectors (PSDs) for pointing, tracking, and stabilization. Typically, two separate detectors are 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 PSDs and as communications receivers. This combined functionality allows for more flexibility and simplicity in optical system design without sacrificing the sensitivity and bandwidth performance of smaller, single-element data receivers. This work presents the development of APD arrays rated for bandwidths beyond 1 GHz with measured carrier ionization ratios of approximately 0.2 at moderate APD gains. We discuss the fabrication and characterization of three types of APD arrays along with their performance as high-speed photodetectors.

  20. 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.

  1. Novel Hybrid CMOS X-ray Detector Developments for Future Large Area and High Resolution X-ray Astronomy Missions

    NASA Astrophysics Data System (ADS)

    Falcone, Abe

    In the coming years, X-ray astronomy will require new soft X-ray detectors that can be read very quickly with low noise and can achieve small pixel sizes over a moderately large focal plane area. These requirements will be present for a variety of X-ray missions that will attempt to address science that was highly ranked by the 2010 Decadal Survey, including missions with science that overlaps with that of IXO and Athena, as well as other missions addressing science topics beyond those of IXO and Athena. An X-ray Surveyor mission was recently chosen by NASA for study by a Science & Technology Definition Team (STDT) so it can be considered as an option for an upcom-ing flagship mission. A mission such as this was endorsed by the NASA long term planning document entitled "Enduring Quests, Daring Visions," and a detailed description of one possible reali-zation of such a mission has been referred to as SMART-X, which was described in a recent NASA RFI response. This provides an example of a future mission concept with these requirements since it has high X-ray throughput and excellent spatial resolution. We propose to continue to modify current active pixel sensor designs, in particular the hybrid CMOS detectors that we have been working with for several years, and implement new in-pixel technologies that will allow us to achieve these ambitious and realistic requirements on a timeline that will make them available to upcoming X-ray missions. This proposal is a continuation of our program that has been work-ing on these developments for the past several years. The first 3 years of the program led to the development of a new circuit design for each pixel, which has now been shown to be suitable for a larger detector array. The proposed activity for the next four years will be to incorporate this pixel design into a new design of a full detector array (2k×2k pixels with digital output) and to fabricate this full-sized device so it can be thoroughly tested and

  2. Assessing the prevalence of hybridization between sympatric Canis species surrounding the red wolf (Canis rufus) recovery area in North Carolina.

    PubMed

    Bohling, Justin H; Waits, Lisette P

    2011-05-01

    Predicting spatial patterns of hybridization is important for evolutionary and conservation biology yet are hampered by poor understanding of how hybridizing species can interact. This is especially pertinent in contact zones where hybridizing populations are sympatric. In this study, we examined the extent of red wolf (Canis rufus) colonization and introgression where the species contacts a coyote (C. latrans) population in North Carolina, USA. We surveyed 22,000km(2) in the winter of 2008 for scat and identified individual canids through genetic analysis. Of 614 collected scats, 250 were assigned to canids by mitochondrial DNA (mtDNA) sequencing. Canid samples were genotyped at 6-17 microsatellite loci (nDNA) and assigned to species using three admixture criteria implemented in two Bayesian clustering programs. We genotyped 82 individuals but none were identified as red wolves. Two individuals had red wolf mtDNA but no significant red wolf nDNA ancestry. One individual possessed significant red wolf nDNA ancestry (approximately 30%) using all criteria, although seven other individuals showed evidence of red wolf ancestry (11-21%) using the relaxed criterion. Overall, seven individuals were classified as hybrids using the conservative criteria and 37 using the relaxed criterion. We found evidence of dog (C. familiaris) and gray wolf (C. lupus) introgression into the coyote population. We compared the performance of different methods and criteria by analyzing known red wolves and hybrids. These results suggest that red wolf colonization and introgression in North Carolina is minimal and provide insights into the utility of Bayesian clustering methods to detect hybridization. © 2011 Blackwell Publishing Ltd.

  3. Photon-to-digital photodiode imaging array

    NASA Astrophysics Data System (ADS)

    Mandl, William J.

    2001-10-01

    MOSAD©, Multiplexed OverSample Analog to Digital conversion, is a low power on focal plane analog to digital, A/D, process that places an oversample A/D at each pixel site. Two designs for a visible light staring array were developed with this approach. One used a silicon photo diode and the other used a photo gate for detection. The array was designed with a 320 X 240 format with the pixels placed on 16 micron centers. There are a total of 76,800 A/D's on the chip. The device is a monolithic integrated circuit that includes the sensors, A/D's and readout circuitry. A production 1.2 micron CCD/CMOS process was used in it construction. The A/D uses charge well switching at the pixel to convert the accumulated analog signal to digital data. There was negligible impact on the pixel area due to the A/D such that a fill factor of 73% was achieved with front side illumination for both approaches. At 400 samples per second, measured on chip power consumption is under 10 milliwatts. Noise measurements at sample rates from 400 samples per second to 1,600 samples per second were taken for both parts. It was found that the photo gate noise performance was four times better than the photo diode. At a nominal 28 times oversample, the photo diode obtained 8 to 9 bits performance and the photo gate achieved 10 to 11 bits. Nonuniformity variation was below the noise floor. No explanation for the difference in noise performance has yet been determined. This development was sponsored by NASA under a SBIR program.

  4. 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.

  5. 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

  6. 480 x 8 hybrid HgCdTe infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Kobayashi, Masako; Wada, Hideo; Okamura, Toshihiro; Kudo, Jun-ichi; Tanikawa, Kunihiro; Hikida, Soichiro; Miyamoto, Yoshihiro; Miyazaki, Shinji; Yoshida, Yukihiro

    2001-10-01

    This paper explains the technologies used for high-performance long linear arrays based on HgCdTe/CMOS hybrid multiplexers with bidirectional Time Delay and Integration (TDI) functions, and it describes the development of the first high-resolution Forward Looking Infrared (FLIR) system with the SXGA format. Long-wavelength Infrared (LWIR) photodiode arrays are fabricated using liquid-phase epitaxially grown HgCdTe on a CdZnTe substrate. Each photodiode array consists of 480x8-element n+/n-on-p diodes formed by B+ implantation. Each photodiode is surrounded by a crosswise drain diode to define the detection area. The diodes with a 10.3-μm cutoff wavelength had a typical zero-bias resistance of 10 MΩ and a shunt resistance of 1 GΩ. Four CMOS Read Out Integrated Circuits (ROICs) were used for bidirectional TDI and multiplex operations where each ROIC summed up and multiplexed eight signals from 120 channels. The ROIC also includes pixel deselection and gain control circuits along with the corresponding memory and writing means. The Infrared Focal Plane Arrays (IRFPAs) had a typical Noise Equivalent Temperature Difference (NETD) of 18 mK after TDI with F/1.55 optics and 10-μs integration. The FLIR system using the 480x8 IRFPA demonstrated a high spatial resolution of 1280 horizontal lines by 960 vertical lines (SXGA format) and NETD of less than 30 mK. The unique algorithm for image enhancement was successfully confirmed to be efficient.

  7. 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.

  8. 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.

  9. Thermal calibration of photodiode sensitivity for atomic force microscopy

    SciTech Connect

    Attard, Phil; Pettersson, Torbjoern; Rutland, Mark W.

    2006-11-15

    The photodiode sensitivity in the atomic force microscope is calibrated by relating the voltage noise to the thermal fluctuations of the cantilever angle. The method accounts for the ratio of the thermal fluctuations measured in the fundamental vibration mode to the total, and also for the tilt and extended tip of the cantilever. The method is noncontact and is suitable for soft or deformable surfaces where the constant compliance method cannot be used. For hard surfaces, the method can also be used to calibrate the cantilever spring constant.

  10. 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.

  11. 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.

  12. Radiation Threshold Levels for Noise Degradation of Photodiodes.

    DTIC Science & Technology

    1986-09-30

    for Noise Degradation of Photodiodes L. W. AUKERMAN , F. L. VERNON, Jr., and Y. SONG Electronics Research Laboratory Laboratory Operations The...PERFORMING ORG. REPORT NUMBER TR-0086 (6925-04)-2 7. AUTHOR(e) S. CONTRACT OR GRANT NUMBER(a) Lee W. Aukerman , Frank L. Vernon, Jr., and Yeong Song...Agency, Washington, D.C. (December 1971). 8. D. H. Seib and L. W. Aukerman , "Photodetectors for the 0.1 to 1.0 4m Spectral Region," Advances in

  13. 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.

  14. Vertically illuminated TW-UTC photodiodes for terahertz generation

    NASA Astrophysics Data System (ADS)

    Barrientos Z., Claudio; Calle, Victor; Diaz, Marcos; Mena, F. Patricio; Vukusic, Josip; Stake, Jan; Michael, Ernest A.

    2010-07-01

    More efficient continuous-wave photonic nearinfrared mixers as terahertz sources are investigated with the motivation to develop a universal photonic local oscillator for astronomical submillimeter/terahertz receiver systems. For this, we develop new concepts for vertically illuminated traveling-wave (TW) photomixers, TW Uni-Travelling Carrier (UTC) photodiodes. Device simulation/modeling and optical/terahertz testing is being done in the new terahertz photonics laboratory at the Electrical Engineering Department of the University of Chile, whereas device fabrication is performed at the MC2 cleanroom facility at Chalmers Technical University. We report on first progress in this direction.

  15. Vertically Illuminated TW-UTC Photodiodes for Terahertz Generation

    NASA Astrophysics Data System (ADS)

    Barrientos, C.; Calle, V.; Diaz, M.; Mena, F. P.; Vukusic, J.; Stake, J.; Michael, E. A.

    2010-03-01

    More efficient continuous-wave photonic near-infrared mixers as terahertz sources are investigated with the motivation to develop a universal photonic local oscillator for astronomical submillimeter/terahertz receiver systems. For this, our group has developed new concepts for vertically illuminated traveling-wave (TW) photomixers. The new device called TW-Uni-Travelling Carrier photodiodes (TW-UTC PD) was simulated, modeled and shall be optical/terahertz tested at the Electrical Engineering Department of the University of Chile, whereas device fabrication is performed at the MC2 cleanroom facility at Chalmers University of technology. We are reporting on first progresses in this direction.

  16. Electrically tuneable spectral responsivity in gated silicon photodiodes

    NASA Astrophysics Data System (ADS)

    Abid, Kamran; Wang, Xingsheng; Khokhar, Ali Z.; Watson, Scott; Al-Hasani, Sulaiman; Rahman, Faiz

    2011-12-01

    We report the observation of electrically tuneable spectral responsivity in silicon-based photodetectors. The current flowing through a lateral p-i-n junction photodiode can be changed by changing either the gate bias or the intensity of incident light, with the devices exhibiting typical optical responsivities of 65 A/W. The peak sensitivity of the device can be changed over the entire visible region by changing the gate voltage in a 5 V range. This happens because with increasing gate bias, an accumulation layer of holes is pulled closer to the Si-SiO2 interface, enhancing the blue response of the device.

  17. Waveguide-integrated telecom-wavelength photodiode in deposited silicon.

    PubMed

    Preston, Kyle; Lee, Yoon Ho Daniel; Zhang, Mian; Lipson, Michal

    2011-01-01

    We demonstrate photodiodes in deposited polycrystalline silicon at 1550 nm wavelength with 0.15 A/W responsivity, 40 nA dark current, and gigahertz time response. Subband absorption is mediated by defects that are naturally present in the polycrystalline material structure. The material exhibits a moderate absorption coefficient of 6 dB/cm, which allows the same microring resonator device to act as both a demultiplexing filter and a photodetector. We discuss the use of deposited silicon-based complementary metal-oxide semiconductor materials for nanophotonic interconnects.

  18. 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.

  19. 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.

  20. Current Kink and Capacitance Frequency Dispersion in Silicon PIN Photodiodes

    NASA Astrophysics Data System (ADS)

    Guo, Xia; Feng, Yajie; Liu, Qiaoli; Wang, Huaqiang; Li, Chong; Hu, Zonghai; He, Xiaoying

    2017-09-01

    Silicon PIN photodiodes in the visible wavelength range have been widely applied in aerospace, defense, security, medical, and scientific instruments because of their high sensitivity and low cost. In this paper, the phenomena of the current kink and the capacitance frequency dispersion are observed. Contamination at the p-type Ohmic contact interface is proposed to explain the current kink effect and capacitance frequency dispersion, according to the temperature-dependent I-V measurement results in which trap-assisted tunneling process demonstrated.

  1. Metalorganic chemical vapor deposition of HgCdTe for photodiode applications

    NASA Astrophysics Data System (ADS)

    Mitra, P.; Schimert, T. R.; Case, F. C.; Starr, R.; Weiler, M. H.; Kestigian, M.; Reine, M. B.

    1995-05-01

    Metalorganic chemical vapor depositon (MOCVD) in situ growth of p-on-n junctions for long wavelength infrared (LWIR) and medium wavelength infrared (MWIR) photodiodes is reported. The interdiffused multilayer process was used for the growth of the HgCdTe junctions on CdTe and CdZnTe substrates. The n-type region was grown undoped while the p-type layer was arsenic doped using tertiarybutylarsine. Following a low temperature anneal in Hg vapor, carrier densities of (0.2-2) x 1015 cm3 and mobilities of (0.7-1.2) x 105 cm2/V-s were obtained for n-type LWIR (x ~ 0.22) layers at 80K. Carrier lifetimes of these layers at 80 K are ~l-2 μs. For the p-type region arsenic doping was controlled in the range of (1-20) x 1016 cm-3. Arsenic doping levels in the junctions were determined by calibrated secondary ion mass spectroscopy depth profile measurements. Composition and doping of the p-on-n heterojunctions could be independently controlled so that the electrical junction could be located deeper than the change in the composition. The graded composition region between the narrow and wide (x = 0.28-0.30) bandgap regions are 1 2 μm depending on the growth temperature. Backside-illuminated variable-area circular mesa photodiode arrays were fabricated on the grown junctions as well as on ion implanted n-on-p MWIR junctions. The spectral responses are classical in shape. Quantum efficiencies at 80K are 42 77% for devices without anti-reflection coating and with cutoff wavelengths of 4.8 11.0 μm. Quantum efficiencies are independent of reverse bias voltage and do not decrease strongly at lower temperatures indicating that valence band barrier effects are not present. 80K RoA of 15.9 Ω-cm2 was obtained for an array with 11.0 μm cutoff. Detailed measurements of the characteristics of the MOCVD in situ grown and implanted photodiodes are reported.

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

    PubMed

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

    2011-03-28

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

  3. Spectral method for characterization of avalanche photodiode working as single-photon detector.

    PubMed

    Cavalcanti, Maria Daniela Santabaia; Mendonça, Fábio Alencar; Ramos, Rubens Viana

    2011-09-01

    In this Letter, a new method for avalanche photodiode characterization, based on the spectral analysis of the photocurrent produced during an avalanche, is proposed. The theory is developed, and an experimental characterization of an avalanche photodiode working in the Geiger mode with CW laser is performed.

  4. Characteristics of Various Photodiode Structures in CMOS Technology with Monolithic Signal Processing Electronics

    SciTech Connect

    Mukhopadhyay, Sourav; Chandratre, V. B.; Sukhwani, Menka; Pithawa, C. K.

    2011-10-20

    Monolithic optical sensor with readout electronics are needed in optical communication, medical imaging and scintillator based gamma spectroscopy system. This paper presents the design of three different CMOS photodiode test structures and two readout channels in a commercial CMOS technology catering to the need of nuclear instrumentation. The three photodiode structures each of 1 mm{sup 2} with readout electronics are fabricated in 0.35 um, 4 metal, double poly, N-well CMOS process. These photodiode structures are based on available P-N junction of standard CMOS process i.e. N-well/P-substrate, P+/N-well/P-substrate and inter-digitized P+/N-well/P-substrate. The comparisons of typical characteristics among three fabricated photo sensors are reported in terms of spectral sensitivity, dark current and junction capacitance. Among the three photodiode structures N-well/P-substrate photodiode shows higher spectral sensitivity compared to the other two photodiode structures. The inter-digitized P+/N-well/P-substrate structure has enhanced blue response compared to N-well/P-substrate and P+/N-well/P-substrate photodiode. Design and test results of monolithic readout electronics, for three different CMOS photodiode structures for application related to nuclear instrumentation, are also reported.

  5. Linearity improvement of high-speed avalanche photodiodes using thin depleted absorber operating with higher order modulation format.

    PubMed

    Nada, Masahiro; Hoshi, Takuya; Yamazaki, Hiroshi; Hashimoto, Toshikazu; Matsuzaki, Hideaki

    2015-10-19

    We present an avalanche photodiode (APD) with high-speed, high-responsivity and high-linearity operation to cope with higher order modulation format, such as pulse-amplitude modulation (PAM). A hybrid absorber configuration with thin depleted region which we newly employed successfully eliminates the space charge effect in the APD while maintaining high responsivity and operating speed. The fabricated APD shows an improved optical-input-electrical-output linearity for an optical input power over -8 dBm, and an optical receiver with this APD achieves both an error-free operation with a KP4 FEC and a high sensitivity of -17 dBm against a 28-Gbaud PAM4 signal.

  6. Fault tolerant photodiode and photogate active pixel sensors

    NASA Astrophysics Data System (ADS)

    Jung, Cory; Chapman, Glenn H.; La Haye, Michelle L.; Djaja, Sunjaya; Cheung, Desmond Y. H.; Lin, Henry; Loo, Edward; Audet, Yves R.

    2005-03-01

    As the pixel counts of digital imagers increase, the challenge of maintaining high yields and ensuring reliability over an imager"s lifetime increases. A fault tolerant active pixel sensor (APS) has been designed to meet this need by splitting an APS in half and operating both halves in parallel. The fault tolerant APS will perform normally in the no defect case and will produce approximately half the output for single defects. Thus, the entire signal can be recovered by multiplying the output by two. Since pixels containing multiple defects are rare, this design can correct for most defects allowing for higher production yields. Fault tolerant photodiode and photogate APS" were fabricated in 0.18-micron technology. Testing showed that the photodiode APS could correct for optically induced and electrically induced faults, within experimental error. The photogate APS was only tested for optically induced defects and also corrects for defects within experimental error. Further testing showed that the sensitivity of fault tolerant pixels was approximately 2-3 times more sensitive than the normal pixels. HSpice simulations of the fault tolerant APS circuit did not show increased sensitivity, however an equivalent normal APS circuit with twice width readout and row transistors was 1.90 times more sensitive than a normal pixel.

  7. 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.

  8. Quantifying the Area at Risk in Reperfused ST-Segment-Elevation Myocardial Infarction Patients Using Hybrid Cardiac Positron Emission Tomography-Magnetic Resonance Imaging.

    PubMed

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

    2016-03-01

    Hybrid positron emission tomography and magnetic resonance allows the advantages of magnetic resonance in tissue characterizing the myocardium to be combined with the unique metabolic insights of positron emission tomography. We hypothesized that the area of reduced myocardial glucose uptake would closely match the area at risk delineated by T2 mapping in ST-segment-elevation myocardial infarction patients. Hybrid positron emission tomography and magnetic resonance using (18)F-fluorodeoxyglucose (FDG) for glucose uptake was performed in 21 ST-segment-elevation myocardial infarction patients at a median of 5 days. Follow-up scans were performed in a subset of patients 12 months later. The area of reduced FDG uptake was significantly larger than the infarct size quantified by late gadolinium enhancement (37.2±11.6% versus 22.3±11.7%; P<0.001) and closely matched the area at risk by T2 mapping (37.2±11.6% versus 36.3±12.2%; P=0.10, R=0.98, bias 0.9±4.4%). On the follow-up scans, the area of reduced FDG uptake was significantly smaller in size when compared with the acute scans (19.5 [6.3%-31.8%] versus 44.0 [21.3%-55.3%]; P=0.002) and closely correlated with the areas of late gadolinium enhancement (R 0.98) with a small bias of 2.0±5.6%. An FDG uptake of ≥45% on the acute scans could predict viable myocardium on the follow-up scan. Both transmural extent of late gadolinium enhancement and FDG uptake on the acute scan performed equally well to predict segmental wall motion recovery. Hybrid positron emission tomography and magnetic resonance in the reperfused ST-segment-elevation myocardial infarction patients showed reduced myocardial glucose uptake within the area at risk and closely matched the area at risk delineated by T2 mapping. FDG uptake, as well as transmural extent of late gadolinium enhancement, acutely can identify viable myocardial segments. © 2016 American Heart Association, Inc.

  9. 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

  10. Gathering effect on dark current for CMOS fully integrated-, PIN-photodiodes

    NASA Astrophysics Data System (ADS)

    Teva, Jordi; Jonak-Auer, Ingrid; Schrank, Franz; Kraft, Jochen; Siegert, Joerg; Wachmann, Ewald

    2010-02-01

    PIN photodiodes are semiconductor devices widely used in a huge range of applications, such as photoconductors, charge-coupled devices, and pulse oximeters. The possibility to combine and to integrate the fabrication of the sensor with its signal conditioning circuitry in a CMOS process flow opens the window to device miniaturization enhancing its properties and lowering the production and assembly costs. This paper presents the design and characterization of silicon based PIN photodiodes integrated in a CMOS commercial process. A high-resistivity, low impurity float zone substrate is chosen as the start material for the PIN photodiode array fabrication in order to fabricate devices with a minimum dark current. The photodiodes in the array are isolated by a guard ring consisting of a n+-p+ diffusions. However, the introduction of the guard ring design, necessary for photodiode-to-photodiode isolation, leads to an increase of the photodiodes dark current. In this article, the new parasitic term on the dark current is identified, formulated, modelled and experimental proven and has finally been used for an accurate design of the guard ring.

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

    PubMed

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

    2015-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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.

  13. Systematic afterpulsing-estimation algorithms for gated avalanche photodiodes.

    PubMed

    Wiechers, Carlos; Ramírez-Alarcón, Roberto; Muñiz-Sánchez, Oscar R; Yépiz, Pablo Daniel; Arredondo-Santos, Alejandro; Hirsch, Jorge G; U'Ren, Alfred B

    2016-09-10

    We present a method designed to efficiently extract optical signals from InGaAs avalanche photodiodes (APDs) operated in gated mode. In particular, our method permits an estimation of the fraction of counts that actually results from the signal being measured, as opposed to being produced by noise mechanisms, specifically by afterpulsing. Our method in principle allows the use of InGaAs APDs at high detection efficiencies, with the full operation bandwidth, either with or without resorting to the application of a dead-time. As we show below, our method can be used in configurations where afterpulsing exceeds the genuine signal by orders of magnitude, even near saturation. The algorithms that we have developed are suitable to be used either in real-time processing of raw detection probabilities or in post-processing applications, after a calibration step has been performed. The algorithms that we propose here can complement technologies designed for the reduction of afterpulsing.

  14. 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.

  15. Avalanche Photodiodes as Fast X-ray Detectors.

    PubMed

    Kishimoto, S

    1998-05-01

    An avalanche photodiode (APD) detector provides a sub-nanosecond time resolution and an output rate of more than 10(8) counts s(-1) of synchrotron X-rays. Moreover, the APD has the advantage of low noise. A review of recent developments of detectors using APD devices designed for X-ray experiments is presented in this paper. One of the detectors has an excellent time response of 100 ps resolution and a narrow width on its response function, 1.4 ns at 10(-5) maximum. The other consists of a stack of four diodes and has a transmission structure. The stacked detector improved the efficiency for X-rays, e.g. 55% at 16.53 keV. The output rates reached more than 10(8) counts s(-1) per device.

  16. Cesium hafnium chloride scintillator coupled with an avalanche photodiode photodetector

    NASA Astrophysics Data System (ADS)

    Kurosawa, S.; Kodama, S.; Yokota, Y.; Horiai, T.; Yamaji, A.; Shoji, Y.; Král, R.; Pejchal, J.; Ohashi, Y.; Kamada, K.; Nikl, M.; Yoshikawa, A.

    2017-02-01

    Optical and scintillation properties of pure Cs2HfCl6 (CHC) single crystals were investigated. In particular, light output and energy resolution were measured using a Si avalanche photodiode (Si-APD), since the Si-APD has sufficient quantum efficiency of around 70 % at emission wavelength region of CHC around 420 nm. This CHC single crystal grown using the vertical Bridgeman method showed light output of 37,000± 2,000 photons/MeV . The FWHM energy resolution was determined to be 3.7± 0.5× (E/662 keV)-0.85± 0.03[%], where E [keV] is the gamma-ray energy. Moreover, the temperature dependence of the light output was stable from -5 to 30 oC, while the light output increased below -10 oC.

  17. Photon-counting techniques with silicon avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Dautet, Henri; Deschamps, P.; Dion, Bruno; MacGregor, Andrew D.; MacSween, D.; McIntyre, Robert J.; Trottier, C.; Webb, Paul P.

    1993-05-01

    Silicon avalanche photodiodes (APD) have been used for photon counting for a number of years. This paper reviews their properties and the associated electronics required for photon counting in the Geiger mode. Significant improvements are reported in overall photon detection efficiencies (approaching 75% at 633 nm), and timing jitter (under 200 ps) achieved at high over-voltages (20 - 30 V). Results obtained using an active-mode fast quench circuit capable of switching over-voltages as high as 20 V (giving photon detection efficiencies in the 50% range), are reported with a dead-time of less than 50 ns. Larger diodes (up to 1 mm diameter), usable in the Geiger mode, which have quantum efficiencies over 80% in the 500 - 800 nm range also are reported.

  18. 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.

  19. 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.

  20. SWIR HgCdTe photodiodes for LADAR applications

    NASA Astrophysics Data System (ADS)

    Boieriu, Paul; Park, J. H.; Hahn, S.-R.; Wijewarnasuriya, Priyalal; Stan, Barry; Sivananthan, S.

    2016-09-01

    The detection of infrared radiation is of great importance for many defense and civilian applications. Eyesafe short-wavelength infrared (SWIR) spectral range is particularly interesting due to atmospheric propagation through obscurants. Applications include low-cost, long-range target identification, identification of heavily obscured targets, obstacle avoidance, and high resolution imaging from a variety of platforms including hand-held devices, unmanned air vehicles, or ground vehicles. HgCdTe grown on CdTe/Si by molecular beam epitaxy (MBE) was processed into mini-arrays for 1.55 μm LADAR applications. Low-capacitance photodiodes (<10 pF) were demonstrated at room temperature with frequency responses exceeding 100 MHz. This paper discusses the device architecture and device performance results.

  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. 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.

  3. Robust Quantum Random Number Generator Based on Avalanche Photodiodes

    NASA Astrophysics Data System (ADS)

    Wang, Fang-Xiang; Wang, Chao; Chen, Wei; Wang, Shuang; Lv, Fu-Sheng; He, De-Yong; Yin, Zhen-Qiang; Li, Hong-Wei; Guo, Guang-Can; Han, Zheng-Fu

    2015-08-01

    We propose and demonstrate a scheme to realize a high-efficiency truly quantum random number generator (RNG) at room temperature (RT). Using an effective extractor with simple time bin encoding method, the avalanche pulses of avalanche photodiode (APD) are converted into high-quality random numbers (RNs) that are robust to slow varying noise such as fluctuations of pulse intensity and temperature. A light source is compatible but not necessary in this scheme. Therefor the robustness of the system is effective enhanced. The random bits generation rate of this proof-of-principle system is 0.69 Mbps with double APDs and 0.34 Mbps with single APD. The results indicate that a high-speed RNG chip based on the scheme is potentially available with an integrable APD array.

  4. Comprehensive analysis of new near-infrared avalanche photodiode structure

    NASA Astrophysics Data System (ADS)

    Czuba, Krzysztof; Jurenczyk, Jaroslaw; Kaniewski, Janusz

    2014-01-01

    The essential steps in simulations of modern separate absorption, grading, charge, and multiplication avalanche photodiode and their results are discussed. All simulations were performed using two commercial technology computer-aided design type software packages, namely Silvaco ATLAS and Crosslight APSYS. Comparison between those two frameworks was made and differences between them were pointed out. Several examples of the influence of changes made in individual layers on overall device characteristics have been shown. Proper selection of models and their parameters as well as its significance on results has been illustrated. Additionally, default values of material parameters were revised and adequate values from the literature were entered. Simulated characteristics of optimized structure were compared with ones obtained from measurements of real devices (e.g., current-voltage curves). Finally, properties of crucial layers in the structure were discussed.

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

    NASA Technical Reports Server (NTRS)

    Rosenfeld, D.; Bahir, G.

    1993-01-01

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

  6. Size- and shape-controlled conversion of tungstate-based inorganic-organic hybrid belts to WO3 nanoplates with high specific surface areas.

    PubMed

    Chen, Deliang; Gao, Lian; Yasumori, Atsuo; Kuroda, Kazuyuki; Sugahara, Yoshiyuki

    2008-10-01

    Two-dimensional monoclinic WO(3) nanoplates with high specific surface areas are synthesized through a novel conversion process using tungstate-based inorganic-organic hybrid micro/nanobelts as precursors. The process developed involves a topochemical transformation of tungstate-based inorganic-organic hybrid belts into WO(3) nanoplates via an intermediate product of H(2)WO(4) nanoplates, utilizing the similarity of the W-O octahedral layers in both H(2)WO(4) and WO(3). The as-obtained WO(3) nanoplates show a single-crystalline nanostructure with the smallest side along the [001] direction. The WO(3) nanoplates are 200-500 nm x 200-500 nm x 10-30 nm in size, and their specific surface areas are up to 180 m(2) g(-1). Photocatalytic measurements of visible-light-driven oxidation of water for O(2) generation in the presence of Ag(+) ions indicate that the activity of the as-obtained WO(3) nanoplates is one order of magnitude higher than that of commercially available WO(3) powders.

  7. Evaluation of high quantum efficiency silicon photodiodes for calibration in the 400 nm to 900 nm spectral region

    NASA Technical Reports Server (NTRS)

    Jorquera, Carlos; Bruegge, Carol; Duval, Valerie

    1992-01-01

    The reflectance and internal quantum efficiency (QE) of three single-element photodiodes are determined using two different light-trapping devices. The QED-200 light trapping device which is based on inversion layer photodiodes exhibits the best performance within the short wavelengths of the visible spectrum (VIS), while the A-O device based on p-n photodiodes, performs best in the long wave VIS up to 950 nm. The combination of the two light-traps provides nearly 100 percent external QE coverage from 400 to 950 nm. The reflectances and internal QE were determined within this spectral range for three photodiodes: UV100, an inversion layer photodiode; X-UV100, a shallow diffused n-p photodiode; and 10DPI/SB, a blue-enhanced p-n photodiode.

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

    PubMed

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

    2016-12-01

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

  9. Ultra-low noise single-photon detector based on Si avalanche photodiode.

    PubMed

    Kim, Yong-Su; Jeong, Youn-Chang; Sauge, Sebastien; Makarov, Vadim; Kim, Yoon-Ho

    2011-09-01

    We report operation and characterization of a lab-assembled single-photon detector based on commercial silicon avalanche photodiodes (PerkinElmer C30902SH, C30921SH). Dark count rate as low as 5 Hz was achieved by cooling the photodiodes down to -80 °C. While afterpulsing increased as the photodiode temperature was decreased, total afterpulse probability did not become significant due to detector's relatively long deadtime in a passively-quenched scheme. We measured photon detection efficiency >50% at 806 nm. © 2011 American Institute of Physics

  10. Improving an organic photodiode by incorporating a tunnel barrier between the donor and acceptor layers

    NASA Astrophysics Data System (ADS)

    Campbell, I. H.; Crone, B. K.

    2012-07-01

    We demonstrate increased photocurrent quantum efficiency in a model donor/acceptor (tetracene/C60) photodiode by incorporating an insulating tunnel barrier between the tetracene and C60 layers. Photodiode efficiency results from the interplay of a number of processes which add to or subtract from the overall device efficiency. The positive rates are those of exciton dissociation and charge separation, the negative rates include exciton and charge transfer complex recombination. We show that by introducing a thin insulating layer between the donor and acceptor layers in a photodiode, we can modify the exciton dissociation and charge transfer complex recombination rates and improve device performance.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    PubMed

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

    2014-12-10

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

  13. Characterization of silicon avalanche photodiodes for photon correlation measurements. 2: Active quenching.

    PubMed

    Brown, R G; Jones, R; Rarity, J G; Ridley, K D

    1987-06-15

    We continue examination of the photon correlation properties of silicon avalanche photodiodes operated in photon-counting mode by extending their operation from that of passive quenching(1) to active quenching, yielding shorter dead time and higher frequency operation.

  14. Characterization of a Photodiode Coupled with a Si Nanowire-FET on a Plastic Substrate

    PubMed Central

    Kwak, Kiyeol; Cho, Kyoungah; Kim, Sangsig

    2010-01-01

    In this study, a laterally coupled device composed of a photodiode and a Si nanowires-field-effect transistor (NWs-FET) is constructed on a plastic substrate and the coupled device is characterized. The photodiode is made of p-type Si NWs and an n-type ZnO film. The Si NWs-FET is connected electrically to the photodiode in order to enhance the latter’s photocurrent efficiency by adjusting the gate voltage of the FET. When the FET is switched on by biasing a gate voltage of −9 V, the photocurrent efficiency of the photodiode is three times higher than that when the FET is switched off by biasing a gate voltage of 0 V. PMID:22163398

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

    PubMed

    Neiswander, R S; Plews, G S

    1975-11-01

    With appropriate preamplifier design and cooled silicon photodiode and input field effect transistor, broad frequency bandwidth (e.g., 0.01 Hz to 100 kHz) performance comparable or better than that of photon noise limited photomultipliers can be achieved. The FET input preamplifier is operated current mode with a large feedback resistance. Consequent limited frequency response of the preamplifier is compensated by treble boosting at the postamplifier. Cooling the photodiode and input FET to 200 K eliminates photodiode dark current and FET gate reverse current shot noises as significant contributors. Remaining noise sources are FET voltage noise, minimized by small input capacitances, and feedback and FET load resistances Johnson noise. At an output SNR of 10, for example, the internal noise and the photon noise are about the same level. Thus the performance gain attributable to the photodiode's high quantum efficiency can be significant.

  16. Optical AND and NOT gates at 40 Gbps using electro-absorption modulator/photodiode pairs.

    SciTech Connect

    Tauke-Pedretti, Anna; Overberg, Mark E.; Skogen, Erik J.; Alford, Charles Fred; Sullivan, Charles Thomas; Vawter, Gregory Allen; Peake, Gregory Merwin; Torres, David L.

    2010-06-01

    We demonstrate an optical gate architecture using electro-absorption modulator/photodiode pairs to perform AND and NOT functions. Optical bandwidth for both gates reach 40 GHz. Also shown are AND gate waveforms at 40 Gbps.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  18. Epitaxially-grown Ge/Si avalanche photodiodes for 1.3 microm light detection.

    PubMed

    Kang, Y; Zadka, M; Litski, S; Sarid, G; Morse, M; Paniccia, M J; Kuo, Y-H; Bowers, J; Beling, A; Liu, H D; McIntosh, D C; Campbell, J; Pauchard, A

    2008-06-23

    We designed and fabricated Ge/Si avalanche photodiodes grown on silicon substrates. The mesa-type photodiodes exhibit a responsivity at 1310 nm of 0.54 A/W, a breakdown voltage thermal coefficient of 0.05%/ degrees C, a 3 dB-bandwidth of 10 GHz. The gain-bandwidth product was measured as 153 GHz. The effective k value extracted from the excess noise factor was 0.1.

  19. High-power high-linearity flip-chip bonded modified uni-traveling carrier photodiode.

    PubMed

    Li, Zhi; Fu, Yang; Piels, Molly; Pan, Huapu; Beling, Andreas; Bowers, John E; Campbell, Joe C

    2011-12-12

    We demonstrate a flip-chip bonded modified uni-traveling carrier (MUTC) photodiode with an RF output power of 0.75 W (28.8 dBm) at 15 GHz and OIP3 as high as 59 dBm. The photodiode has a responsivity of 0.7 A/W, 3-dB bandwidth > 15 GHz, and saturation photocurrent > 180 mA at 11 V reverse bias.

  20. Reducing the thermal stress in a heterogeneous material stack for large-area hybrid optical silicon-lithium niobate waveguide micro-chips

    NASA Astrophysics Data System (ADS)

    Weigel, P. O.; Mookherjea, S.

    2017-04-01

    The bonding of silicon-on-insulator (SOI) to lithium niobate-on-insulator (LNOI) is becoming important for a new category of linear and nonlinear micro-photonic optical devices. In studying the bonding of SOI to LNOI through benzocyclobutene (BCB), a popular interlayer bonding dielectric used in hybrid silicon photonic devices, we use thermal stress calculations to suggest that BCB thickness does not affect thermal stress in this type of structure, and instead, thermal stress can be mitigated satisfactorily by matching the handles of the SOI and LNOI. We bond LNOI with a silicon handle to a silicon chip, remove the handle on the LNOI side, and thermally cycle the bonded stack repeatedly from room temperature up to 300°C and back down without incurring thermal stress cracks, which do appear when using LNOI with a lithium niobate handle, regardless of the BCB thickness. We show that this process can be used to create many hybrid silicon-lithium niobate waveguiding structures on a single patterned SOI chip bonded to a large-area (16 mm × 4.2 mm) lithium niobate film.

  1. Modeling of InGaAs/InAlAs/InP avalanche photodiodes with undepleted absorber

    NASA Astrophysics Data System (ADS)

    Kaniewski, Janusz; Jurenczyk, Jaroslaw; Zak, Dariusz; Muszalski, Jan

    2012-01-01

    For high-bit rate and long-haul receivers in optical telecommunication systems the avalanche photodiodes are preferred since they offer an improvement of the receiver sensitivity by several decibels. Recently critical sensing and imaging applications stimulated development of modified avalanche photodiodes structures operating in 1.55 μm spectral range. For these devices speed is not further critical. Instead, very low current densities and low multiplication noises are the main requirements. The most advanced structure of avalanche photodiodes is known as Separate Absorption, Grading, Charge and Multiplication (SAGCM). In the present work the performance of uncooled InGaAs/InAlAs/InP avalanche photodiodes operating near 1.55 μm has been studied theoretically. Device modeling based on advanced drift - diffusion model with commercial Crosslight APSYS software has been performed. Conventional SAGCM avalanche photodiodes as well as devices with a relatively thick undepleted p-type InGaAs absorption region and thin InAlAs multiplication layer have been considered. This type of avalanche photodiodes enables to increase device quantum efficiency, reduce dark current and eliminate impact ionization processes within absorbing layer. Extensive calculations allowed for detailed analysis of individual regions of the device and determination of their influence on diode characteristics.

  2. Numerical analysis of the temperature field in silicon avalanche photodiode by millisecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Di; Jin, Guangyong; Wei, Zhi; Zhao, Hongyu

    2016-10-01

    Recent years, millisecond laser become a research hotspot. Avalanche photodiode (APD) based on silicon structure has excellent characteristics such as low noise and high-sensitivity. It is key components in receives for long-haul high-bit-rate optical communication system. The failure mechanism of silicon APD remains quite unknown, although some silicon p-i-n photodiode failure modes have been speculated. The COMSOL Multiphysics finite element analysis software was utilized in this paper. And the 2D model, which based on heat conduction equation, was established to simulate the temperature field of the silicon avalanche photodiode irradiated by millisecond laser. The model presented in the following section is a work which considers only melting of silicon by a millisecond laser pulse. The temperature dependences of material properties are taken into account, which has a great influence on the temperature fields indicated by the numerical results. The pulsed laser-induced transient temperature fields in silicon avalanche photodiode are obtained, which will be useful in the research on the mechanism of interactions between millisecond laser and photodiode. The evolution of temperature at the central point of the top surface, the temperature distribution along the radial direction in the end of laser irradiation and the temperature distribution along the axial direction in the end of laser irradiation were considered. Meanwhile, the fluence threshold value was obtained through the model. The conclusions had a reference value for revealing the mechanism of interactions between millisecond laser and the silicon avalanche photodiode.

  3. Development of printed ITO coatings on PET and PEN foil for flexible organic photodiodes

    NASA Astrophysics Data System (ADS)

    Heusing, S.; Oliveira, P. W.; Kraker, E.; Haase, A.; Palfinger, C.; Veith, M.

    2008-04-01

    ITO (tin doped indium oxide) coatings with a sheet resistance of 2 to 3 kΩ(square) were produced by gravure printing process on PET and PEN foil. The printing paste consisted of ITO nanoparticles which were dispersed in a solvent by using a surfactant. The dispersion was mixed with a binder and a photo initiator before printing. The printed films were hardened under UV-irradiation at low temperatures (< 130°C). The sheet resistance could be decreased by heat treatment at 120°C under forming gas atmosphere (N II/H II) to 1.5 kΩ(square). The transmission of the ITO coated PET and PEN foils is more than 80 % in the visible range. The ITO films were directly used as the bottom electrode in an organic photodiode (OPD). The setup of the OPD originates from the well known Tang photodiode, consisting of a stacked layer of copper phthalocyanine (p-type material) and perylene tetracarboxylic bisbenzimidazole (n-type material). The photodiodes are characterised via current-voltage (I-V) characteristics. The performance of the photodiodes with printed ITO on plastic substrates could be improved by the deposition of a PEDOT/PSS layer (Baytron (R) P) on the ITO coated foils and was then comparable to the performance of photodiodes with semi-transparent gold as anode on PET substrates. These results demonstrate the suitability of the printed ITO layers as anode for organic photodiodes.

  4. 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

  5. Modeling scintillator-photodiodes as detectors for megavoltage CT.

    PubMed

    Monajemi, T T; Steciw, S; Fallone, B G; Rathee, S

    2004-05-01

    The use of cadmium tungstate (CdWO4) and cesium iodide [CsI(Tl)] scintillation detectors is studied in megavoltage computed tomography (MVCT). A model describing the signal acquired from a scintillation detector has been developed which contains two steps: (1) the calculation of the energy deposited in the crystal due to MeV photons using the EGSnrc Monte Carlo code; and (2) the transport of the optical photons generated in the crystal voxels to photodiodes using the optical Monte Carlo code DETECT2000. The measured detector signals in single CdWO4 and CsI(Tl) scintillation crystals of base 0.275 x 0.8 cm2 and heights 0.4, 1, 1.2, 1.6 and 2 cm were, generally, in good agreement with the signals calculated with the model. A prototype detector array which contains 8 CdWO4 crystals, each 0.275 x 0.8 x 1 cm3, in contact with a 16-element array of photodiodes was built. The measured attenuation of a Cobalt-60 beam as a function of solid water thickness behaves linearly. The frequency dependent modulation transfer function [MTF(f)], noise power spectrum [NPS(f)], and detective quantum efficiency [DQE(f)] were measured for 1.25 MeV photons (in a Cobalt-60 beam). For 6 MV photons, only the MTF(f) was measured from a linear accelerator, where large pulse-to-pulse fluctuations in the output of the linear accelerator did not allow the measurement of the NPS(f). A two-step Monte Carlo simulation was used to model the detector's MTF(f), NPS(f) and DQE(f). The DQE(0) of the detector array was found to be 26% and 19% for 1.25 MeV and 6 MV photons, respectively. For 1.25 MeV photons, the maximum discrepancies between the measured and modeled MTF(f), relative NPS(f) and the DQE(f) were found to be 1.5%, 1.2%, and 1.9%, respectively. For the 6 MV beam, the maximum discrepancy between the modeled and the measured MTF(f) was found to be 2.5%. The modeling is sufficiently accurate for designing appropriate detectors for MVCT.

  6. Online management of lithium-ion battery based on time-triggered controller area network for fuel-cell hybrid vehicle applications

    NASA Astrophysics Data System (ADS)

    Li, Xiangjun; Li, Jianqiu; Xu, Liangfei; Ouyang, Minggao; Han, Xuebing; Lu, Languang; Lin, Chengtao

    This paper introduces a state of charge (SOC) estimation algorithm that was implemented for an automotive lithium-ion battery system used in fuel-cell hybrid vehicles (FCHVs). The proposed online control strategy for the lithium-ion battery, based on the Ah current integration method and time-triggered controller area network (TTCAN), incorporates a signal filter and adaptive modifying concepts to estimate the Li 2MnO 4 battery SOC in a timely manner. To verify the effectiveness of the proposed control algorithm, road test experimentation was conducted with an FCHV using the proposed SOC estimation algorithm. It was confirmed that the control technique can be used to effectively manage the lithium-ion battery and conveniently estimate the SOC.

  7. Simultaneous data communication and position sensing with an impact ionization engineered avalanche photodiode array for free space optical communication

    NASA Astrophysics Data System (ADS)

    Ferraro, Mike S.; Mahon, Rita; Rabinovich, William S.; Murphy, James L.; Dexter, James L.; Clark, William R.; Waters, William D.; Vaccaro, Kenneth; Krejca, Brian D.

    2017-02-01

    Photodetectors in free space optical communication systems perform two functions: reception of data communication signals and position sensing for pointing, tracking, and stabilization. Traditionally, the optical receive path in an FSO system is split into separate paths for data detection and position sensing. The need for separate paths is a consequence of conflicting performance criteria between position sensitive detectors (PSD) and data detectors. Combining the functionality of both detector types requires that the combinational sensor not only have the bandwidth to support high data rate communication but the active area and spatial discrimination to accommodate position sensing. In this paper we present a large area, concentric five element impact ionization engineered avalanche photodiode array rated for bandwidths beyond 1GHz with a measured carrier ionization ratio of less than 0.1 at moderate APD gains. The integration of this array as a combinational sensor in an FSO system is discussed along with the development of a pointing and stabilization algorithm.

  8. Use of models in large-area forest surveys: comparing model-assisted, model-based and hybrid estimation

    Treesearch

    Goran Stahl; Svetlana Saarela; Sebastian Schnell; Soren Holm; Johannes Breidenbach; Sean P. Healey; Paul L. Patterson; Steen Magnussen; Erik Naesset; Ronald E. McRoberts; Timothy G. Gregoire

    2016-01-01

    This paper focuses on the use of models for increasing the precision of estimators in large-area forest surveys. It is motivated by the increasing availability of remotely sensed data, which facilitates the development of models predicting the variables of interest in forest surveys. We present, review and compare three different estimation frameworks where...

  9. Current-mode CMOS hybrid image sensor

    NASA Astrophysics Data System (ADS)

    Benyhesan, Mohammad Kassim

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

  10. High Response in a Tellurium-Supersaturated Silicon Photodiode

    NASA Astrophysics Data System (ADS)

    Wang, Xi-Yuan; Huang, Yong-Guang; Liu, De-Wei; Zhu, Xiao-Ning; Zhu, Hong-Liang

    2013-03-01

    Single crystalline silicon supersaturated with tellurium are formed by ion implantation followed by excimer nanosecond pulsed laser melting (PLM). The lattice damaged by ion implantation is restored during the PLM process, and dopants are effectively activated. The hyperdoped layer exhibits high and broad optical absorption from 400 to 2500nm. The n+ p photodiodes fabricated from these materials show high response (6.9A/W at 1000nm) with reverse bias 12 V at room temperature. The corresponding cut-off wavelength is 1258nm. The amount of gain and extended cut-off wavelength both increase with increasing reverse bias voltage; above 100% external quantum efficiency is observed even at a reverse bias of 1 V. The cut-off wavelength with 0 V bias is shorter than the commercial silicon detector. This implies that the Burstein-Moss shift is due to hyperdoping. The amount of the extended cut-off wavelength increases with increasing reverse bias voltage, suggesting existence of the Franz—Keldysh effect.

  11. Spectral correction of silicon photodiode solar radiation detectors

    SciTech Connect

    Zhou, C.; Michalsky, J.

    1994-12-31

    The multi-filter rotating shadowband radiometer (MFRSR) is a ground- based instrument that uses a silicon photodiode sensor to measure shortwave global and diffuse horizontal irradiance from which direct normal irradiance is calculated. Besides this multiplexing advantage, silicon sensors are rugged, stable and have a fast time response. On the other hand, silicon sensors are both thermally and spectrally sensitive. They, as do all pyranometric sensors, have an imperfect cosine response, especially at high solar-zenith angles. In the MFRSR two of these problems are solved. The MFRSR`s cosine response is measured and corrected. An automatic heater maintains the MFRSR detector at a constant temperature near 40 {degree}C. This paper describes a correction scheme, based on sky conditions, to account for the remaining spectral bias. The data base for these corrections was collected in Albany, New York, during 1993. The MFRSR and WMO firstclass thermopile instruments were sampled every 15 seconds and 5- minute averages were compared. The differences in time response between silicon and thermopile instruments contributes substantially to the remaining root-mean-square error reported.

  12. A New Positioning Algorithm for Position-Sensitive Avalanche Photodiodes

    PubMed Central

    Zhang, Jin; Olcott, Peter D.; Levin, Craig S.

    2013-01-01

    We are using a novel position sensitive avalanche photodiode (PSAPD) for the construction of a high resolution positron emission tomography (PET) camera. Up to now most researchers working with PSAPDs have been using an Anger-like positioning algorithm involving the four corner readout signals of the PSAPD. This algorithm yields a significant non-linear spatial “pin-cushion” distortion in raw crystal positioning histograms. In this paper, we report an improved positioning algorithm, which combines two diagonal corner signals of the PSAPD followed by a 45° rotation to determine the X or Y position of the interaction. We present flood positioning histogram data generated with the old and new positioning algorithms using a 3 × 4 array of 2 × 2 × 3 mm3 and a 3 × 8 array of 1 × 1 × 3 mm3 of LSO crystals coupled to 8 × 8 mm2 PSAPDs. This new algorithm significantly reduces the pin-cushion distortion in raw flood histogram image. PMID:24307743

  13. New gamma detector modules based on micropixel avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Ahmadov, F.; Ahmadov, G.; Guliyev, E.; Madatov, R.; Sadigov, A.; Sadygov, Z.; Suleymanov, S.; Akberov, R.; Nuriyev, S.; Zerrouk, F.

    2017-01-01

    In this paper presented the results of the ionizing radiation detector modules, which developed on the basis of a new generation of micropixel avalanche photodiode (MAPD) of MAPD-3NK type. The samples were produced in cooperation with the Zecotek Photonics and characterized by the following parameters: sensitive area—3.7 mm × 3.7 mm, density of pixels—10000 pixels/mm2, photon detection efficiency—35-40% (at wavelength of 450-550 nm) and operation voltage—91 V. The beta particle and gamma ray detection performance of MAPD with different single scintillation crystal such as NaI, LFS and p-terphenyl was investigated. The gamma ray detector modules demonstrated a perfect linear behavior of detected signal amplitudes as a function of the gamma ray energy (from 26.3 keV up to 1.33 MeV). Energy resolution for 662 keV gamma rays was 11.2% and the minimum detectable energy was 26.3 keV.

  14. A New Positioning Algorithm for Position-Sensitive Avalanche Photodiodes.

    PubMed

    Zhang, Jin; Olcott, Peter D; Levin, Craig S

    2007-06-01

    We are using a novel position sensitive avalanche photodiode (PSAPD) for the construction of a high resolution positron emission tomography (PET) camera. Up to now most researchers working with PSAPDs have been using an Anger-like positioning algorithm involving the four corner readout signals of the PSAPD. This algorithm yields a significant non-linear spatial "pin-cushion" distortion in raw crystal positioning histograms. In this paper, we report an improved positioning algorithm, which combines two diagonal corner signals of the PSAPD followed by a 45° rotation to determine the X or Y position of the interaction. We present flood positioning histogram data generated with the old and new positioning algorithms using a 3 × 4 array of 2 × 2 × 3 mm(3) and a 3 × 8 array of 1 × 1 × 3 mm(3) of LSO crystals coupled to 8 × 8 mm(2) PSAPDs. This new algorithm significantly reduces the pin-cushion distortion in raw flood histogram image.

  15. Avalanche photodiodes and quenching circuits for single-photon detection

    NASA Astrophysics Data System (ADS)

    Cova, S.; Ghioni, M.; Lacaita, A.; Samori, C.; Zappa, F.

    1996-04-01

    Avalanche photodiodes, which operate above the breakdown voltage in Geiger mode connected with avalanche-quenching circuits, can be used to detect single photons and are therefore called single-photon avalanche diodes SPAD's. Circuit configurations suitable for this operation mode are critically analyzed and their relative merits in photon counting and timing applications are assessed. Simple passive-quenching circuits (PQC's), which are useful for SPAD device testing and selection, have fairly limited application. Suitably designed active-quenching circuits (AQC's) make it possible to exploit the best performance of SPAD's. Thick silicon SPAD's that operate at high voltages (250-450 V) have photon detection efficiency higher than 50% from 540-to 850-nm wavelength and still approximately 3% at 1064 nm. Thin silicon SPAD's that operate at low voltages (10-50 V) have 45% efficiency at 500 nm, declining to 10% at 830 nm and to as little as 0.1% at 1064 nm. The time resolution achieved in photon timing is 20 ps FWHM with thin SPAD's; it ranges from 350 to 150 ps FWHM with thick SPAD's. The achieved minimum counting dead time and maximum counting rate are 40 ns and 10 Mcps with thick silicon SPAD's, 10 ns and 40 Mcps with thin SPAD's. Germanium and III-V compound semiconductor SPAD's extend the range of photon-counting techniques in the near-infrared region to at least 1600-nm wavelength.

  16. 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.

  17. Avalanche photodiodes and quenching circuits for single-photon detection.

    PubMed

    Cova, S; Ghioni, M; Lacaita, A; Samori, C; Zappa, F

    1996-04-20

    Avalanche photodiodes, which operate above the breakdown voltage in Geiger mode connected with avalanche-quenching circuits, can be used to detect single photons and are therefore called singlephoton avalanche diodes SPAD's. Circuit configurations suitable for this operation mode are critically analyzed and their relative merits in photon counting and timing applications are assessed. Simple passive-quenching circuits (PQC's), which are useful for SPAD device testing and selection, have fairly limited application. Suitably designed active-quenching circuits (AQC's) make it possible to exploit the best performance of SPAD's. Thick silicon SPAD's that operate at high voltages (250-450 V) have photon detection efficiency higher than 50% from 540- to 850-nm wavelength and still ~3% at 1064 nm. Thin silicon SPAD's that operate at low voltages (10-50 V) have 45% efficiency at 500 nm, declining to 10% at 830 nm and to as little as 0.1% at 1064 nm. The time resolution achieved in photon timing is 20 ps FWHM with thin SPAD's; it ranges from 350 to 150 ps FWHM with thick SPAD's. The achieved minimum counting dead time and maximum counting rate are 40 ns and 10 Mcps with thick silicon SPAD's, 10 ns and 40 Mcps with thin SPAD's. Germanium and III-V compound semiconductor SPAD's extend the range of photon-counting techniques in the near-infrared region to at least 1600-nm wavelength.

  18. Foliage penetration optimization for Geiger-mode avalanche photodiode lidar

    NASA Astrophysics Data System (ADS)

    Johnson, Steven E.

    2013-05-01

    Geiger-mode avalanche photodiode (GMAPD) Lidar systems can be used to image targets that are partially concealed by foliage. This application of GMAPD Lidar is challenging because most APDs operating in Geiger- mode report only one range measurement per transmitted laser pulse. If a GMAPD makes a foliage range measurement, it cannot make a range measurement to a target concealed by the foliage. When too much laser energy is received, the vast majority of range measurements are from the foliage and only a small percentage are from the target. Some GMAPD Lidar systems can report their average detection probability during operation. The average detection probability, which is often called "P-det", is calculated over an array of GMAPDs, over multiple laser pulses, or over both. However, the detection probability does not distinguish between target range measurements, foliage range measurements, and noise events. In this paper, it is shown that when certain collection parameters are known, that the probability of detecting a target obscured by foliage can be maximized by selecting the appropriate "P-det". It is also shown that for a typical foliage penetration scenario where most of the reflected laser energy is from the foliage that operating with a "P-det" between 65% and 80% produces a near-maximum target detection probability.

  19. 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.

  20. 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.

  1. Single photon counting linear mode avalanche photodiode technologies

    NASA Astrophysics Data System (ADS)

    Williams, George M.; Huntington, Andrew S.

    2011-10-01

    The false count rate of a single-photon-sensitive photoreceiver consisting of a high-gain, low-excess-noise linear-mode InGaAs avalanche photodiode (APD) and a high-bandwidth transimpedance amplifier (TIA) is fit to a statistical model. The peak height distribution of the APD's multiplied dark current is approximated by the weighted sum of McIntyre distributions, each characterizing dark current generated at a different location within the APD's junction. The peak height distribution approximated in this way is convolved with a Gaussian distribution representing the input-referred noise of the TIA to generate the statistical distribution of the uncorrelated sum. The cumulative distribution function (CDF) representing count probability as a function of detection threshold is computed, and the CDF model fit to empirical false count data. It is found that only k=0 McIntyre distributions fit the empirically measured CDF at high detection threshold, and that false count rate drops faster than photon count rate as detection threshold is raised. Once fit to empirical false count data, the model predicts the improvement of the false count rate to be expected from reductions in TIA noise and APD dark current. Improvement by at least three orders of magnitude is thought feasible with further manufacturing development and a capacitive-feedback TIA (CTIA).

  2. 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.

  3. 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.

  4. 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

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

    PubMed

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

    2013-01-01

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

  6. Hybrid gas-to-particle conversion and chemical vapor deposition for production of high-surface area films

    NASA Astrophysics Data System (ADS)

    Nguyen, Quynh Tan

    A hybrid process, based upon gas-to-particle conversion and chemical vapor deposition, is presented as an alternative technique for producing porous films with the main advantages of solvent-free, low-substrate temperature operation. Starting from solid precursors, nanoparticles were produced in the vapor phase. Downstream of this reaction zone, these nanoparticles were collected via thermophoresis onto a cooled substrate forming a porous film. Initially, alumina (Al2O3) films were produced. Later, multi-component processing was explored by incorporating platinum (Pt) nanoparticles into the Al2O3 matrix leading to the production of Pt/Al 2O3 films by two routes: simultaneous precursor injection processing or by a layer-by-layer approach. In single component processing, the formation of nanoparticle aggregates was evident within the amorphous Al2O3 films. Aggregates, composed of these particles, are likely held together by relatively weak van der Waals forces leading to the observed poor physical cohesion. In multi-component processing, reasonable control of composition and distribution of species is possible with Pt nanoparticles appearing to be co-agglomerated with alumina. Deposited crystalline Pt nanoparticles may encourage the crystallization of the amorphous Al2O3. Finally, from chemisorption results, the produced sample appears to have potentially greater catalytic activity than a commercially available standard. A model is in development to study nanoparticle interactions with a gas and deposition occurring in stagnation flow onto the cooled horizontal substrate within the tubular reactor. Using velocity and temperature fields generated from numerical solutions to the Navier-Stokes and energy equations, particle trajectories were calculated from the summation of drag, gravitational, thermophoretic, and Brownian forces. In rectangular coordinates, cooling stage width to reactor diameter ratio, deposition stage temperature, and initial velocity were the

  7. Nanoscale avalanche photodiodes for highly sensitive and spatially resolved photon detection.

    PubMed

    Hayden, Oliver; Agarwal, Ritesh; Lieber, Charles M

    2006-05-01

    Integrating nanophotonics with electronics could enhance and/or enable opportunities in areas ranging from communications and computing to novel diagnostics. Light sources and detectors are important elements for integration, and key progress has been made using semiconducting nanowires and carbon nanotubes to yield electrically driven sources and photoconductor detectors. Detection with photoconductors has relatively poor sensitivity at the nanometre scale, and thus large amplification is required to detect low light levels and ultimately single photons with reasonable response time. Here, we report avalanche multiplication of the photocurrent in nanoscale p-n diodes consisting of crossed silicon-cadmium sulphide nanowires. Electrical transport and optical measurements demonstrate that the nanowire avalanche photodiodes (nanoAPDs) have ultrahigh sensitivity with detection limits of less than 100 photons, and subwavelength spatial resolution of at least 250 nm. Crossed nanowire arrays also show that nanoAPDs are reproducible and can be addressed independently without cross-talk. NanoAPDs and arrays could open new opportunities for ultradense integrated systems, sensing and imaging applications.

  8. Developments in HgCdTe avalanche photodiode technology and applications

    NASA Astrophysics Data System (ADS)

    Ashcroft, Andrew; Baker, Ian

    2010-04-01

    SELEX Galileo has developed avalanche photodiode technology in HgCdTe to serve a whole range of applications in defence, security, commercial and space research. Burst-illumination LIDAR (BIL), using a near-infrared pulse laser and a fast, gated detector, is now adopted for most long range imaging applications. New results from range trials using prototype systems based on multifunctional and 3D detectors are reported. In the astronomy field, APD arrays at 2.5 μm cutoff can provide near-single photon sensitivity for future wavefront sensors and interferometric applications. Under a contract from European Southern Observatories arrays have been successfully demonstrated with gains up to 20× and negligible dark current at 77K. Under a European Space Agency contract, a large area, single element detector has been designed for the 2.015μm CO2 absorption line. The sensor is specifically designed to be operated at 200K so that thermoelectric cooling is viable. The element is made up of many sub-pixel diodes each deselectable to ensure high breakdown in the macro-pixel. The latest results of the detector and its associated transimpedance amplifier (TIA) are presented.

  9. A three-phase time-correlation image sensor using pinned photodiode active pixels

    NASA Astrophysics Data System (ADS)

    Han, Sangman; Iwahori, Tomohiro; Sawada, Tomonari; Kawahito, Shoji; Ando, Shigeru

    2010-01-01

    A time correlation (TC) image sensor is a device that produces 3-phase time-correlated signals between the incident light intensity and three reference signals. A conventional implementation of the TC image sensor using a standard CMOS technology works at low frequency and with low sensitivity. In order to achieve higher modulation frequency and high sensitivity, the TC image sensor with a dual potential structure using a pinned diode is proposed. The dual potential structure is created by changing the impurity doping concentration in the two different potential regions. In this structure, high-frequency modulation can be achieved, while maintaining a sufficient light receiving area. A prototype TC image sensor with 366×390pixels is implemented with 0.18-μm 1P4M CMOS image sensor technology. Each pixel with the size of 12μm×12μm has one pinned photodiode with the dual potential structure, 12 transistors and 3capacitors to implement three-parallel-output active pixel circuits. A fundamental operation of the implemented TC sensor is demonstrated.

  10. A hybrid MBE-based growth method for large-area synthesis of stacked hexagonal boron nitride/graphene heterostructures

    PubMed Central

    Wofford, Joseph M.; Nakhaie, Siamak; Krause, Thilo; Liu, Xianjie; Ramsteiner, Manfred; Hanke, Michael; Riechert, Henning; J. Lopes, J. Marcelo

    2017-01-01

    Van der Waals heterostructures combining hexagonal boron nitride (h-BN) and graphene offer many potential advantages, but remain difficult to produce as continuous films over large areas. In particular, the growth of h-BN on graphene has proven to be challenging due to the inertness of the graphene surface. Here we exploit a scalable molecular beam epitaxy based method to allow both the h-BN and graphene to form in a stacked heterostructure in the favorable growth environment provided by a Ni(111) substrate. This involves first saturating a Ni film on MgO(111) with C, growing h-BN on the exposed metal surface, and precipitating the C back to the h-BN/Ni interface to form graphene. The resulting laterally continuous heterostructure is composed of a top layer of few-layer thick h-BN on an intermediate few-layer thick graphene, lying on top of Ni/MgO(111). Examinations by synchrotron-based grazing incidence diffraction, X-ray photoemission spectroscopy, and UV-Raman spectroscopy reveal that while the h-BN is relaxed, the lattice constant of graphene is significantly reduced, likely due to nitrogen doping. These results illustrate a different pathway for the production of h-BN/graphene heterostructures, and open a new perspective for the large-area preparation of heterosystems combining graphene and other 2D or 3D materials. PMID:28240323

  11. Relationship between isoseismal area and magnitude of historical earthquakes in Greece by a hybrid fuzzy neural network method

    NASA Astrophysics Data System (ADS)

    Tselentis, G.-A.; Sokos, E.

    2012-01-01

    In this paper we suggest the use of diffusion-neural-networks, (neural networks with intrinsic fuzzy logic abilities) to assess the relationship between isoseismal area and earthquake magnitude for the region of Greece. It is of particular importance to study historical earthquakes for which we often have macroseismic information in the form of isoseisms but it is statistically incomplete to assess magnitudes from an isoseismal area or to train conventional artificial neural networks for magnitude estimation. Fuzzy relationships are developed and used to train a feed forward neural network with a back propagation algorithm to obtain the final relationships. Seismic intensity data from 24 earthquakes in Greece have been used. Special attention is being paid to the incompleteness and contradictory patterns in scanty historical earthquake records. The results show that the proposed processing model is very effective, better than applying classical artificial neural networks since the magnitude macroseismic intensity target function has a strong nonlinearity and in most cases the macroseismic datasets are very small.

  12. A hybrid MBE-based growth method for large-area synthesis of stacked hexagonal boron nitride/graphene heterostructures.

    PubMed

    Wofford, Joseph M; Nakhaie, Siamak; Krause, Thilo; Liu, Xianjie; Ramsteiner, Manfred; Hanke, Michael; Riechert, Henning; J Lopes, J Marcelo

    2017-02-27

    Van der Waals heterostructures combining hexagonal boron nitride (h-BN) and graphene offer many potential advantages, but remain difficult to produce as continuous films over large areas. In particular, the growth of h-BN on graphene has proven to be challenging due to the inertness of the graphene surface. Here we exploit a scalable molecular beam epitaxy based method to allow both the h-BN and graphene to form in a stacked heterostructure in the favorable growth environment provided by a Ni(111) substrate. This involves first saturating a Ni film on MgO(111) with C, growing h-BN on the exposed metal surface, and precipitating the C back to the h-BN/Ni interface to form graphene. The resulting laterally continuous heterostructure is composed of a top layer of few-layer thick h-BN on an intermediate few-layer thick graphene, lying on top of Ni/MgO(111). Examinations by synchrotron-based grazing incidence diffraction, X-ray photoemission spectroscopy, and UV-Raman spectroscopy reveal that while the h-BN is relaxed, the lattice constant of graphene is significantly reduced, likely due to nitrogen doping. These results illustrate a different pathway for the production of h-BN/graphene heterostructures, and open a new perspective for the large-area preparation of heterosystems combining graphene and other 2D or 3D materials.

  13. Polymer planar lightwave circuit based hybrid-integrated coherent receiver for advanced modulation signals

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Han, Yang; Liang, Zhongcheng; Chen, Yongjin

    2012-11-01

    Applying coherent detection technique to advanced modulation formats makes it possible to electronically compensate the signal impairments. A key issue for a successful deployment of coherent detection technique is the availability of cost-efficient and compact integrated receivers, which are composed of an optical 90° hybrid mixer and four photodiodes (PDs). In this work, three different types of optical hybrids are fabricated with polymer planar lightwave circuit (PLC), and hybridly integrated with four vertical backside illuminated III-V PDs. Their performances, such as the insertion loss, the transmission imbalance, the polarization dependence and the phase deviation of 90° hybrid will be discussed.

  14. Signal and noise properties of position-sensitive avalanche photodiodes.

    PubMed

    Yang, Yongfeng; Wu, Yibao; Farrell, Richard; Dokhale, Purushottam A; Shah, Kanai S; Cherry, Simon R

    2011-10-07

    After many years of development, position-sensitive avalanche photodiodes (PSAPDs) are now being incorporated into a range of scintillation detector systems, including those used in high-resolution small-animal PET and PET/MR scanners. In this work, the signal, noise, signal-to-noise ratio (SNR), flood histogram and timing resolution were measured for lutetium oxyorthosilicate (LSO) scintillator arrays coupled to PSAPDs ranging in size from 10 to 20 mm, and the optimum bias voltage and working temperature were determined. Variations in the SNR performance of PSAPDs with the same dimensions were small, but the SNR decreased significantly with increasing PSAPD size and increasing temperature. Smaller PSAPDs (10 mm and 15 mm in width) produced acceptable flood histograms at 24 °C, and cooling lower than 16 °C produced little improvement. The optimum bias voltage was about 25 V below the break down voltage. The larger 20 mm PSAPDs have lower SNR and require cooling to 0-7 °C for acceptable performance. The optimum bias voltage is also lower (35 V or more below the break down voltage depending on the temperature). Significant changes in the timing resolution were observed as the bias voltage and temperature varied. Higher bias voltages provided better timing resolution. The best timing resolution obtained for individual crystals was 2.8 ns and 3.3 ns for the 10 mm and 15 mm PSAPDs, respectively. The results of this work provide useful guidance for selecting the bias voltage and working temperature for scintillation detectors that incorporate PSAPDs as the photodetector.

  15. Photodiode Preamplifier for Laser Ranging With Weak Signals

    NASA Technical Reports Server (NTRS)

    Abramovici, Alexander; Chapsky, Jacob

    2007-01-01

    An improved preamplifier circuit has been designed for processing the output of an avalanche photodiode (APD) that is used in a high-resolution laser ranging system to detect laser pulses returning from a target. The improved circuit stands in contrast to prior such circuits in which the APD output current pulses are made to pass, variously, through wide-band or narrow-band load networks before preamplification. A major disadvantage of the prior wide-band load networks is that they are highly susceptible to noise, which degrades timing resolution. A major disadvantage of the prior narrow-band load networks is that they make it difficult to sample the amplitudes of the narrow laser pulses ordinarily used in ranging. In the improved circuit, a load resistor is connected to the APD output and its value is chosen so that the time constant defined by this resistance and the APD capacitance is large, relative to the duration of a laser pulse. The APD capacitance becomes initially charged by the pulse of current generated by a return laser pulse, so that the rise time of the load-network output is comparable to the duration of the return pulse. Thus, the load-network output is characterized by a fast-rising leading edge, which is necessary for accurate pulse timing. On the other hand, the resistance-capacitance combination constitutes a lowpass filter, which helps to suppress noise. The long time constant causes the load network output pulse to have a long shallow-sloping trailing edge, which makes it easy to sample the amplitude of the return pulse. The output of the load network is fed to a low-noise, wide-band amplifier. The amplifier must be a wide-band one in order to preserve the sharp pulse rise for timing. The suppression of noise and the use of a low-noise amplifier enable the ranging system to detect relatively weak return pulses.

  16. Signal and Noise Properties of Position-Sensitive Avalanche Photodiodes

    PubMed Central

    Yang, Yongfeng; Wu, Yibao; Farrell, Richard; Dokhale, Purushottam A.; Shah, Kanai S.; Cherry, Simon R.

    2011-01-01

    After many years of development, position-sensitive avalanche photodiodes (PSAPDs) are now being incorporated into a range of scintillation detector systems, including those used in high-resolution small-animal PET and PET/MR scanners. In this work, the signal, noise, signal-to-noise ratio (SNR), flood histogram and timing resolution were measured for lutetium oxyorthosilicate (LSO) scintillator arrays coupled to PSAPDs ranging in size from 10–20 mm, and the optimum bias voltage and working temperature determined. Variations in the SNR performance of PSAPDs with the same dimensions were small, but the SNR decreased significantly with increasing PSAPD size and increasing temperature. Smaller PSAPDs (10 mm and 15 mm in width) produced acceptable flood histograms at 24 °C, and cooling lower than 16 °C produced little improvement. The optimum bias voltage was about 25 V below the break down voltage. The larger 20 mm PSAPDs have lower SNR and require cooling to 0–7 °C for acceptable performance. The optimum bias voltage also is lower (35 V or more below the break down voltage depending on the temperature). Significant changes in the timing resolution were observed as the bias voltage and temperature were varied. Higher bias voltages provided better timing resolution. The best timing resolution obtained for individual crystals was 2.8 ns and 3.3 ns for the 10 mm and 15 mm PSAPDs, respectively. The results of this work provide useful guidance for selecting the bias voltage and working temperature for scintillation detectors that incorporate PSAPDs as the photodetector. PMID:21896961

  17. 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.

  18. InGaAsP-based uni-travelling carrier photodiode structure grown by solid source molecular beam epitaxy.

    PubMed

    Natrella, Michele; Rouvalis, Efthymios; Liu, Chin-Pang; Liu, Huiyun; Renaud, Cyril C; Seeds, Alwyn J

    2012-08-13

    We report the first InGaAsP-based uni-travelling carrier photodiode structure grown by Solid Source Molecular Beam Epitaxy; the material contains layers of InGaAsP as thick as 300 nm and a 120 nm thick InGaAs absorber. Large area vertically illuminated test devices have been fabricated and characterised; the devices exhibited 0.1 A/W responsivity at 1550 nm, 12.5 GHz -3 dB bandwidth and -5.8 dBm output power at 10 GHz for a photocurrent of 4.8 mA. The use of Solid Source Molecular Beam Epitaxy enables the major issue associated with the unintentional diffusion of zinc in Metal Organic Vapour Phase Epitaxy to be overcome and gives the benefit of the superior control provided by MBE growth techniques without the costs and the risks of handling toxic gases of Gas Source Molecular Beam Epitaxy.

  19. Black silicon n-type photodiodes with high response over wide spectral range

    NASA Astrophysics Data System (ADS)

    Heinonen, Juha; Juntunen, Mikko A.; Laine, Hannu S.; Vähänissi, Ville; Repo, Päivikki; Dönsberg, Timo; Savin, Hele

    2017-05-01

    Commercial photodiodes suffer from reflection losses and different recombination losses that reduce the collection efficiency of photogenerated charge carriers. Recently, we realized a near-ideal silicon photodiode, which steps closer to the physical performance limits of silicon photodiodes than any other silicon photodiode realized before. Our device exhibits an external quantum efficiency above 95% over the wavelength range of 235 - 980 nm, and provides a very high response at incident angles of up to 70 degrees. The high quantum efficiency is reached by 1) virtually eliminating front surface reflectance by forming a "black silicon" nanostructured surface having dimensions in the range of wavelength of optical light and 2) using an induced junction for signal collection, formed by negatively charged alumina, instead of a conventional doped p-n junction. Here, we describe the latest efforts in further development of the photodiode technology. In particular, we report improvements both in the short wavelength response via better control of the surface quality, and superior response to photons with energies close to the silicon bandgap.

  20. Aerosol optical depth as observed by the Mars Science Laboratory REMS UV photodiodes

    NASA Astrophysics Data System (ADS)

    Smith, Michael D.; Zorzano, María-Paz; Lemmon, Mark; Martín-Torres, Javier; Mendaza de Cal, Teresa

    2016-12-01

    Systematic observations taken by the REMS UV photodiodes on a daily basis throughout the landed Mars Science Laboratory mission provide a highly useful tool for characterizing aerosols above Gale Crater. Radiative transfer modeling is used to model the approximately 1.75 Mars Years of observations taken to date taking into account multiple scattering from aerosols and the extended field of view of the REMS UV photodiodes. The retrievals show in detail the annual cycle of aerosol optical depth, which is punctuated with numerous short timescale events of increased optical depth. Dust deposition onto the photodiodes is accounted for by comparison with aerosol optical depth derived from direct imaging of the Sun by Mastcam. The effect of dust on the photodiodes is noticeable, but does not dominate the signal. Cleaning of dust from the photodiodes was observed in the season around Ls=270°, but not during other seasons. Systematic deviations in the residuals from the retrieval fit are indicative of changes in aerosol effective particle size, with larger particles present during periods of increased optical depth. This seasonal dependence of aerosol particle size is expected as dust activity injects larger particles into the air, while larger aerosols settle out of the atmosphere more quickly leading to a smaller average particle size over time.

  1. Aerosol Optical Depth as Observed by the Mars Science Laboratory REMS UV Photodiodes

    NASA Astrophysics Data System (ADS)

    Smith, M. D.; Zorzano, M. P.; Lemmon, M. T.; Martín-Torres, J.; Mendaza de Cal, T.

    2016-12-01

    Systematic observations taken by the REMS UV photodiodes on a daily basis throughout the landed Mars Science Laboratory mission provide a highly useful tool for characterizing aerosols above Gale Crater. Radiative transfer modeling is used to model the more than two Mars Years of observations taken to date taking into account multiple scattering from aerosols and the extended field of view of the REMS UV photodiodes. The retrievals show in detail the annual cycle of aerosol optical depth, which is punctuated with numerous short timescale events of increased optical depth. Dust deposition onto the photodiodes is accounted for by comparison with aerosol optical depth derived from direct imaging of the Sun by Mastcam. The effect of dust on the photodiodes is noticeable, but does not dominate the signal. Cleaning of dust from the photodiodes was observed in the season around Ls=270°, but not during other seasons. Systematic deviations in the residuals from the retrieval fit are indicative of changes in aerosol effective particle size, with larger particles present during periods of increased optical depth. This seasonal dependence of aerosol particle size is expected as dust activity injects larger particles into the air, while larger aerosols settle out of the atmosphere more quickly leading to a smaller average particle size over time.

  2. X-ray imaging sensor arrays on foil using solution processed organic photodiodes and organic transistors

    NASA Astrophysics Data System (ADS)

    Kumar, Abhishek; Moet, Date; van der Steen, Jan-Laurens; Tripathi, Ashutosh; Rodriguez, Francisco G.; Maas, Joris; Simon, Matthias; Reutten, Walter; Douglas, Alexander; Raaijmakers, Rob; Malinowski, Pawel E.; Myny, Kris; Shafique, Umar; Andriessen, Ronn; Heremans, Paul; Gelinck, Gerwin

    2014-05-01

    We demonstrate organic imaging sensor arrays fabricated on flexible plastic foil with the solution processing route for both photodiodes and thin film transistors. We used the photovoltaic P3HT:PCBM blend for fabricating the photodiodes using spin coating and pentacene as semiconductor material for the TFTs. Photodiodes fabricated with P3HT:PCBM absorb in the green part of the visible spectrum which matches with the typical scintillator output wavelength. The arrays consist of 32x32 pixels with variation in pixel resolution of 200μmx200μm, 300μmx300μm and of 1mmx1mm. The accurate reproducibility of shadow images of the objects demonstrates the potential of these arrays for imaging purposes. We also demonstrate that the crosstalk is relatively insignificant despite the fact that the active photodiode forms a continuous layer in the array. Since both photodiodes and TFTs are made of organic material, they are processed at low temperatures below 150°C on foil which means that these imaging sensors can be flexible, light weight and low cost when compared to conventional amorphous silicon based imaging sensors on rigid substrates. In combination with a scintillator on top of the arrays, we show the potential of these arrays for the X-ray imaging applications.

  3. 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.

  4. 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

  5. Aerosol Optical Depth as Observed by the Mars Science Laboratory REMS UV Photodiodes

    NASA Technical Reports Server (NTRS)

    Smith, M. D.; Zorzano, M.-P.; Lemmon, M.; Martin-Torres, J.; Mendaza de Cal, T.

    2017-01-01

    Systematic observations taken by the REMS UV photodiodes on a daily basis throughout the landed Mars Science Laboratory mission provide a highly useful tool for characterizing aerosols above Gale Crater. Radiative transfer modeling is used to model the approximately two Mars Years of observations taken to date taking into account multiple scattering from aerosols and the extended field of view of the REMS UV photodiodes. The retrievals show in detail the annual cycle of aerosol optical depth, which is punctuated with numerous short timescale events of increased optical depth. Dust deposition onto the photodiodes is accounted for by comparison with aerosol optical depth derived from direct imaging of the Sun by Mastcam. The effect of dust on the photodiodes is noticeable, but does not dominate the signal. Cleaning of dust from the photodiodes was observed in the season around Ls=270deg, but not during other seasons. Systematic deviations in the residuals from the retrieval fit are indicative of changes in aerosol effective particle size, with larger particles present during periods of increased optical depth. This seasonal dependence of aerosol particle size is expected as dust activity injects larger particles into the air, while larger aerosols settle out of the atmosphere more quickly leading to a smaller average particle size over time. A full description of these observations, the retrieval algorithm, and the results can be found in Smith et al. (2016).

  6. 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.

  7. Photon counting performance measurements of transfer electron InGaAsP photocathode hybrid photomultiplier tubes at 1064 nm wavelength

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoli; Krainak, Michael A.; Hasselbrack, William B.; La Rue, Ross A.

    2007-05-01

    We report the test results of a hybrid photomultiplier tube (HPMT) with a transfer electron (TE) InGaAsP photocathode and GaAs Schottky avalanche photodiode (APD) anode. Unlike Geiger mode InGaAsP APDs, these HPMTs (also known as intensified photodiode (IPD), vacuum APD, or hybrid photodetector) operate in linear mode without the need for quenching and gating. Their greatest advantages are wide dynamic range, high speed, large photosensitive area, and potential for photon counting and analog detection dual mode operation. The photon detection efficiency we measured was 25% at 1064 nm wavelength with a dark count rate of 60,000/s at -22 degrees Celsius. The output pulse width in response to a single photon detection is about 0.9 ns. The maximum count rate was 90 Mcts/s and was limited solely by the speed of the discriminator used in the measurement (10 ns dead time). The spectral response of these devices extended from 900 to 1300 nm. We also measured the HPMT response to 60 ps laser pulses. The average output pulse amplitude increased monotonically with the input pulse energy, which suggested that we can resolve photon number in an incident pulse. The jitter of the HPMT output was found to be about 0.5 ns standard deviation and depended on bias voltage applied to the TE photocathode. To our knowledge, these HPMTs are the most sensitive non gating photon detectors at 1064 nm wavelength, and they will have many applications in laser altimeters, atmospheric lidars, and free space laser communication systems.

  8. Hybrid photodetector for single-molecule spectroscopy and microscopy

    PubMed Central

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

    2011-01-01

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

  9. Hybrid photodetector for single-molecule spectroscopy and microscopy.

    PubMed

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

    2008-02-15

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

  10. Temperature dependence of commercial 4H-SiC UV Schottky photodiodes for X-ray detection and spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

    Two commercial-off-the-shelf (COTS) 4H-SiC UV photodiodes have been investigated for their suitability as low-cost high temperature tolerant X-ray detectors. Electrical characterisation of the photodiodes which had different active areas (0.06 mm2 and 0.5 mm2) is reported over the temperature range 0 °C to 140 °C together with measurements of the X-ray photocurrents generated when the detectors were illuminated with an 55Fe radioisotope X-ray source. The 0.06 mm2 photodiode was also investigated as a photon counting spectroscopic X-ray detector across the temperature range 0 °C to 100 °C. The depletion widths (at 120 V reverse bias) of the two diodes were found to be 2.3 μm and 4.5 μm, for the 0.06 mm2 and 0.5 mm2 detectors respectively, at 140 °C. Both devices had low leakage currents (<10 pA) at temperatures ≤40 °C even at high electric field strengths (500 kV/cm for 0.06 mm2 diode; 267 kV/cm for 0.5 mm2 diode). At 140 °C and similar field strengths (514 kV/cm for 0.06 mm2 diode; 269 kV/cm for 0.5 mm2 diode), the leakage currents of both diodes were <2 nA (corresponding to leakage current densities of 2.4 μA/cm2 and 0.3 μA/cm2 for each diode respectively). The results demonstrated that both devices could function as current mode detectors of soft X-rays at the temperatures <80 °C and that when coupled to a low noise charge sensitive preamplifier, the smaller diode functioned as a photon counting spectroscopic X-ray detector at temperatures ≤100 °C with modest energy resolution (1.6 keV FWHM at 5.9 keV at 0 °C; 2.6 keV FWHM at 5.9 keV at 100 °C). Due to their temperature tolerance, wide commercial availability, and the radiation hardness of SiC, such detectors are expected to find utility in future low-cost nanosatellite (cubesat) missions and cost-sensitive industrial applications.

  11. 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.

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

    DOE PAGES

    Martinez, Nicholas J. D.; Derose, Christopher T.; Brock, Reinhard W.; ...

    2016-08-09

    Here, 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 intomore » a 50 Ω load and open eye diagrams with 13 Gbps pseudo-random data at 1550 nm.« less

  13. Blue-enhanced thin-film photodiode for dual-screen x-ray imaging

    SciTech Connect

    Vygranenko, Y.; Vieira, M.; Sazonov, A.; Heiler, G.; Tredwell, T.; Nathan, A.

    2009-12-28

    This article reports on a-Si:H-based low-leakage blue-enhanced photodiodes for dual-screen x-ray imaging detectors. Doped nanocrystalline silicon was incorporated in both the n- and p-type regions to reduce absorption losses for light incoming from the top and bottom screens. The photodiode exhibits a dark current density of 900 pA/cm{sup 2} and an external quantum efficiency up to 90% at a reverse bias of 5 V. In the case of illumination through the tailored p-layer, the quantum efficiency of 60% at a 400 nm wavelength is almost double that for the conventional a-Si:H n-i-p photodiode.

  14. Effects of low-level boron doping on the photocurrent of amorphous silicon Schottky photodiodes

    NASA Astrophysics Data System (ADS)

    Kakinuma, H.; Kasuya, Y.; Sakamoto, M.; Shibata, S.

    1989-03-01

    The effects of low-level boron doping on the photocurrent-electric field (Jph-F) characteristics of amorphous silicon Schottky photodiodes were investigated by measuring the Jph-F characteristics of a lightly B-doped photodiode with a configuration of Cr/a-Si:H/tin-doped indium oxide (ITO). The Jph-F curves, which were found to be strongly dependent on the B-doping ratio, were analyzed on the basis of Crandall's (1984) theory, and the B-doping dependencies of the mobility-lifetime (mu-tau) product for electrons and holes were deduced. The effects of low-level B-doping on the mu-tau products and space charges of the photodiodes were discussed in terms of the charge state of the dangling bond state.

  15. 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.

  16. Some n-p (Hg,Cd)Te photodiodes for 8-14 micrometer heterodyne applications

    NASA Technical Reports Server (NTRS)

    Shanley, J. F.; Flanagan, C. T.

    1980-01-01

    The results describing the dc and CO2 laser heterodyne characteristics of a three element photodiode array and single element and four element photodiode arrays are presented. The measured data shows that the n(+)-p configuration is capable of achieving bandwidths of 475 to 725 MHz and noise equivalent powers of 3.2 x 10 to the minus 20th power W/Hz at 77 K and 1.0 x 10 to the minus 19th power W/Hz at 145 K. The n(+)-n(-)-p photodiodes exhibited wide bandwidths (approximately 2.0 GHz) and fairly good effective heterodyne quantum efficiencies (approximately 13-30 percent at 2.0 GHz). Noise equivalent powers ranging from 1.44 x 10 to the minus 19th power W/Hz to 6.23 x 10 to the minus 20th power W/Hz were measured at 2.0 GHz.

  17. Photosensitivity of Te-doped silicon photodiodes fabricated using femtosecond laser irradiation.

    PubMed

    Li, Rui; Du, Lingyan; Tang, Fei; Jiang, Yadong; Wu, Zhiming

    2016-12-20

    Microstructured Te-doped silicon is prepared via a femtosecond laser irradiating Si coated with Si-Te bilayer films, and photodiodes are successfully fabricated from this material. The samples are thermally annealed at 773 K for three different time durations. The effects of annealing time on microstructures, infrared absorptance, and photosensitivity of Te-doped silicon are investigated. From the scanning electronic microscope images and the optical absorptance spectra, the results show that the infrared absorptance decreases with the increase of annealing time durations, while the infrared photoresponse follows an opposite tendency. At 1064 nm, the responsivity achieves 2.4836 A/W at -10  V reverse bias for the Te-doped silicon photodiode annealed at 775 K for 2 h, which is higher than that of usual commercial Si photodiodes. These results are important for the fabrication of Te-doped silicon and facilitate its application in infrared detectors.

  18. 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.

  19. 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.

  20. 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.

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

    SciTech Connect

    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.

    2016-08-09

    Here, 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.

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

    DOE PAGES

    Martinez, Nicholas J. D.; Derose, Christopher T.; Brock, Reinhard W.; ...

    2016-08-09

    Here, 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 intomore » a 50 Ω load and open eye diagrams with 13 Gbps pseudo-random data at 1550 nm.« less

  3. Design, fabrication, and characterization of mid wavelength infrared avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Mallick, Shubhrangshu

    Photodetectors with high bandwidth and internal gain are required to detect highly attenuated optical signals for defense applications and long distance communication. Modern laser detection and ranging (LADAR) systems as well as weapon systems, used for long range military and astronomical applications, need to detect, recognize and track a variety of targets under a wide spectrum of atmospheric conditions. A continually varying atmospheric conditions and optical absorption by carbon dioxide, carbon monoxide and water vapor pose severe threats for the proper recognition of the target. The choice of an additional amplification stage along with the detection stage becomes obvious to enhance the signal to noise ratio at the receiver. Avalanche Photodiode (APD) plays a unique role by combing the detection and amplification stage and hence reduces the complexity. But due to the probabilistic nature associated with the incident radiation absorption and multiplication of the photo-generated carriers, the noise level (known as excess noise) of an APD increases and might result in the deterioration of the signal to noise ratio at the detector output. Participation of both electrons and holes in the avalanche mechanism increases the probability, hence the excess noise at the detector output. So, the goal of the APD design lies in the fact of the minimization of the excess noise along with a reasonable multiplication gain. In this research, two material systems, II-VI based Hg1-xCd xTe on Si, and III-V based InAs/GaSb strained layer superlattice (SLS) was studied extensively to achieve the noiseless avalanche characteristics in the mid wavelength infrared region. The electronic bandstructure of the multiplication region of these APDs were designed with the help of 14 band k.p model. The doping and thickness of individual layers were designed with the help of Atlas and Sentaurus simulation platform. The devices were fabricated using standard UV Photo-lithography and wet

  4. High-performance fused indium gallium arsenide/silicon photodiode

    NASA Astrophysics Data System (ADS)

    Kang, Yimin

    Modern long haul, high bit rate fiber-optic communication systems demand photodetectors with high sensitivity. Avalanche photodiodes (APDs) exhibit superior sensitivity performance than other types of photodetectors by virtual of its internal gain mechanism. This dissertation work further advances the APD performance by applying a novel materials integration technique. It is the first successful demonstration of wafer fused InGaAs/Si APDs with low dark current and low noise. APDs generally adopt separate absorption and multiplication (SAM) structure, which allows independent optimization of materials properties in two distinct regions. While the absorption material needs to have high absorption coefficient in the target wavelength range to achieve high quantum efficiency, it is desirable for the multiplication material to have large discrepancy between its electron and hole ionization coefficients to reduce noise. According to these criteria, InGaAs and Si are the ideal materials combination. Wafer fusion is the enabling technique that makes this theoretical ideal an experimental possibility. APDs fabricated on the fused InGaAs/Si wafer with mesa structure exhibit low dark current and low noise. Special device fabrication techniques and high quality wafer fusion reduce dark current to nano ampere level at unity gain, comparable to state-of-the-art commercial III/V APDs. The small excess noise is attributed to the large difference in ionization coefficients between electrons and holes in silicon. Detailed layer structure designs are developed specifically for fused InGaAs/Si APDs based on principles similar to those used in traditional InGaAs/InP APDs. An accurate yet straightforward technique for device structural parameters extraction is also proposed. The extracted results from the fabricated APDs agree with device design parameters. This agreement also confirms that the fusion interface has negligible effect on electric field distributions for devices fabricated

  5. In-house time-resolved photocrystallography on the millisecond timescale using a gated X-ray hybrid pixel area detector.

    PubMed

    Casaretto, Nicolas; Schaniel, Dominik; Alle, Paul; Wenger, Emmanuel; Parois, Pascal; Fournier, Bertrand; Bendeif, El Eulmi; Palin, Cyril; Pillet, Sébastien

    2017-08-01

    With the remarkable progress of accelerator-based X-ray sources in terms of intensity and brightness, the investigation of structural dynamics from time-resolved X-ray diffraction methods is becoming widespread in chemistry, biochemistry and materials science applications. Diffraction patterns can now be measured down to the femtosecond time-scale using X-ray free electron lasers or table-top laser plasma X-ray sources. On the other hand, the recent developments in photon counting X-ray area detectors offer new opportunities for time-resolved crystallography. Taking advantage of the fast read-out, the internal stacking of recorded images, and the gating possibilities (electronic shutter) of the XPAD hybrid pixel detector, we implemented a laboratory X-ray diffractometer for time-resolved single-crystal X-ray diffraction after pulsed laser excitation, combined with transient optical absorption measurement. The experimental method and instrumental setup are described in detail, and validated using the photoinduced nitrosyl linkage isomerism of sodium nitroprusside, Na2[Fe(CN)5NO]·2H2O, as proof of principle. Light-induced Bragg intensity relative variations ΔI(hkl)/I(hkl) of the order of 1%, due to the photoswitching of the NO ligand, could be detected with a 6 ms acquisition window. The capabilities of such a laboratory time-resolved experiment are critically evaluated.

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

    PubMed

    Diepold, Marc; Fernandes, Luis M P; Machado, Jorge; Amaro, Pedro; Abdou-Ahmed, Marwan; Amaro, Fernando D; Antognini, Aldo; Biraben, François; Chen, Tzu-Ling; Covita, Daniel S; Dax, Andreas J; Franke, Beatrice; Galtier, Sandrine; Gouvea, Andrea L; Götzfried, Johannes; Graf, Thomas; Hänsch, Theodor W; Hildebrandt, Malte; Indelicato, Paul; Julien, Lucile; Kirch, Klaus; Knecht, Andreas; Kottmann, Franz; Krauth, Julian J; Liu, Yi-Wei; Monteiro, Cristina M B; Mulhauser, Françoise; Naar, Boris; Nebel, Tobias; Nez, François; Santos, José Paulo; dos Santos, Joaquim M F; Schuhmann, Karsten; Szabo, Csilla I; Taqqu, David; Veloso, João F C A; Voss, Andreas; Weichelt, Birgit; Pohl, Randolf

    2015-05-01

    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.

  7. Ultralow-noise readout circuit with an avalanche photodiode: toward a photon-number-resolving detector.

    PubMed

    Tsujino, Kenji; Akiba, Makoto; Sasaki, Masahide

    2007-03-01

    The charge-integration readout circuit was fabricated to achieve an ultralow-noise preamplifier for photoelectrons generated in an avalanche photodiode with linear mode operation at 77 K. To reduce the various kinds of noise, the capacitive transimpedance amplifier was used and consisted of low-capacitance circuit elements that were cooled with liquid nitrogen. As a result, the readout noise is equal to 3.0 electrons averaged for a period of 40 ms. We discuss the requirements for avalanche photodiodes to achieve photon-number-resolving detectors below this noise level.

  8. Look-back-upon tree recurrence method for Geiger-mode avalanche photodiode performance prediction.

    PubMed

    Peng, Zhao; Yan, Zhang; Yuming, Hua; Weiping, Qian

    2015-08-15

    This Letter, for the first time, proposes the look-back-upon tree recurrence (LTR) method based on the Poisson statistics for discrete time to predict the performance of Geiger-mode avalanche photodiodes with a short dead time. The results of the proposed method correspond to the results of previous methods for diverse input fluxes. The LTR method possesses very low time and space complexity to allow for the real-time analysis of the Geiger-mode avalanche photodiodes' performance over the entire ranges of dead time and input diversity.

  9. 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.

  10. 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.

  11. 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)

  12. Probing higher order correlations of the photon field with photon number resolving avalanche photodiodes.

    PubMed

    Dynes, J F; Yuan, Z L; Sharpe, A W; Thomas, O; Shields, A J

    2011-07-04

    We demonstrate the use of two high speed avalanche photodiodes in exploring higher order photon correlations. By employing the photon number resolving capability of the photodiodes the response to higher order photon coincidences can be measured. As an example we show experimentally the sensitivity to higher order correlations for three types of photon sources with distinct photon statistics. This higher order correlation technique could be used as a low cost and compact tool for quantifying the degree of correlation of photon sources employed in quantum information science.

  13. 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.

  14. 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.

  15. A novel optimized hybrid fuzzy logic intelligent PID controller for an interconnected multi-area power system with physical constraints and boiler dynamics.

    PubMed

    Gomaa Haroun, A H; Li, Yin-Ya

    2017-09-14

    In the fast developing world nowadays, load frequency control (LFC) is considered to be a most significant role for providing the power supply with good quality in the power system. To deliver a reliable power, LFC system requires highly competent and intelligent control technique. Hence, in this article, a novel hybrid fuzzy logic intelligent proportional-integral-derivative (FLiPID) controller has been proposed for LFC of interconnected multi-area power systems. A four-area interconnected thermal power system incorporated with physical constraints and boiler dynamics is considered and the adjustable parameters of the FLiPID controller are optimized using particle swarm optimization (PSO) scheme employing an integral square error (ISE) criterion. The proposed method has been established to enhance the power system performances as well as to reduce the oscillations of uncertainties due to variations in the system parameters and load perturbations. The supremacy of the suggested method is demonstrated by comparing the simulation results with some recently reported heuristic methods such as fuzzy logic proportional-integral (FLPI) and intelligent proportional-integral-derivative (PID) controllers for the same electrical power system. the investigations showed that the FLiPID controller provides a better dynamic performance and outperform compared to the other approaches in terms of the settling time, and minimum undershoots of the frequency as well as tie-line power flow deviations following a perturbation, in addition to perform appropriate settlement of integral absolute error (IAE). Finally, the sensitivity analysis of the plant is inspected by varying the system parameters and operating load conditions from their nominal values. It is observed that the suggested controller based optimization algorithm is robust and perform satisfactorily with the variations in operating load condition, system parameters and load pattern. Copyright © 2017 ISA. Published by

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  17. Fast XUV 16 × 16 Array Hybrid Module for Plasma Imaging Applications

    NASA Astrophysics Data System (ADS)

    Alekseyev, Andrey G.; Belov, Alexandr M.; Zabrodsky, Vladimir V.; Sukhanov, Vladislav L.; Sorokin, Andrey A.; Peterson, Byron J.

    A hybrid matrix array detector is developed for ultra-fast plasma imaging applications with the use of XUV Si photodiodes (SPD diodes) manufactured according to Ioffe Institute original technology. A basic 16 × 16 hybrid module is comprised of eight stacked sub-modules with 2 × 16 linear SPD diode arrays combined with a circuit board with a 32-channel preamplifier and four 8-channel fast multiplexers. Array front size is 31 × 31 mm2 with ˜25 % sensitive area. The module has a “zero-edge” design providing an option of stacking into the larger arrays, if necessary. The data acquisition system (DAS) consists of eight 4-channel synchronous 12-bit ADC modules with 40 MS/s upper sampling rate, thus providing less than 1 μs minimum time for the complete read-out of the array. Each channel has a 64 MB on-board memory limiting the duration of the acquired period to 0.8 sec at the maximum sampling rate. A common TCP/IP Ethernet protocol is used for the data transmission into the main PC operating as a DAS control console, data preview and storage computer.

  18. 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.; D'Ambrosio, Philip

    2016-11-01

    High-sensitivity photodetectors serve two purposes in free-space optical communication: data reception and position sensing for pointing, tracking, and stabilization. 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 and communications receivers because of the conflicting performance criteria. 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, which is often seen in highly scintillated terrestrial and maritime optical links. While the Naval Research Laboratory 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 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 APD array rated for bandwidths beyond 1 GHz with measured carrier ionization ratios of 0.05 to 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.

  19. A study of the timing properties of position-sensitive avalanche photodiodes

    PubMed Central

    Wu, Yibao; Ng, Thomas SC; Yang, Yongfeng; Shah, Kanai; Farrell, Richard; Cherry, Simon R

    2009-01-01

    In this paper we study position-dependent timing shifts and timing resolution in position sensitive avalanche photodiodes (PSAPDs) and their effect on the coincidence window used in positron emission tomography (PET) systems using these devices. There is a delay in PSAPD signals that increases as the excitation position moves from the corner to the center of the device and the timing resolution concurrently worsens. The difference in timing between the center and corner can be up to 30.7 ns for a 14×14 mm2 area PSAPD. This means that a PSAPD-based PET system could require a very wide coincidence timing window (>60 ns) if this effect is not corrected, although the individual crystal pairs still have full-width half-maximum (FWHM) timing resolutions better than 7.4 ns. In addition to characterizing the timing properties of PSAPDs, two correction methods were developed and applied to data from a pair of PSAPD detectors. These two timing offset corrections reduced the timing shift of a crystal pair from 52.4 ns to 9.7 ns or 1.3 ns, improved FWHM timing resolution of the detector pair from 24.6 ns to 9.5 ns or 6.0 ns and reduced the timing window (sufficient to cover at least twice the FWHM for all crystal pairs) from 65.1 ns to 22.0 ns or 15.2 ns respectively. A two-step timing alignment method is proposed for a PET system consisting of multiple PSAPDs. Lastly, the effect of PSAPD size on the timing performance was also evaluated. PMID:19671971

  20. A study of the timing properties of position-sensitive avalanche photodiodes.

    PubMed

    Wu, Yibao; Ng, Thomas S C; Yang, Yongfeng; Shah, Kanai; Farrell, Richard; Cherry, Simon R

    2009-09-07

    In this paper, we study position-dependent timing shifts and timing resolution in position sensitive avalanche photodiodes (PSAPDs) and their effects on the coincidence window used in positron emission tomography (PET) systems using these devices. There is a delay in PSAPD signals that increases as the excitation position moves from the corner to the center of the device and the timing resolution concurrently worsens. The difference in timing between the center and the corner can be up to 30.7 ns for a 14 x 14 mm(2) area PSAPD. This means that a PSAPD-based PET system could require a very wide coincidence timing window (>60 ns) if this effect is not corrected, although the individual crystal pairs still have full-width half-maximum (FWHM) timing resolutions better than 7.4 ns. In addition to characterizing the timing properties of PSAPDs, two correction methods were developed and applied to data from a pair of PSAPD detectors. These two timing offset corrections reduced the timing shift of a crystal pair from 52.4 ns to 9.7 ns or 1.3 ns, improved the FWHM timing resolution of the detector pair from 24.6 ns to 9.5 ns or 6.0 ns and reduced the timing window (sufficient to cover at least twice the FWHM for all crystal pairs) from 65.1 ns to 22.0 ns or 15.2 ns, respectively. A two-step timing alignment method is proposed for a PET system consisting of multiple PSAPDs. Lastly, the effect of PSAPD size on the timing performance was also evaluated.

  1. State-of-the-art MCT photodiodes for cutting-edge sensor applications by AIM

    NASA Astrophysics Data System (ADS)

    Figgemeier, H.; Hanna, S.; Eich, D.; Fries, P.; Mahlein, K.-M.; Wenisch, J.; Schirmacher, W.; Beetz, J.; Breiter, R.

    2017-02-01

    For about 30 years, AIM has been ranking among the leading global suppliers for high-performance MCT infrared detectors, with its portfolio spanning the photosensitivity cut-off range from the SWIR to the VLWIR and from 1st generation to 3rd generation FPA devices. To meet the market demands for SWaP-C- and IR-detectors with additional functionalities such as multicolor detection, AIM employs both LPE and MBE technology. From AIḾs line of highest-performance single color detectors fabricated by LPE, we will present our latest excellent results of 5.3 μm cut-off MWIR MCT detectors with 1024x768 pixels and a 10 μm pixel pitch. AIM's powerful low dark current LWIR and VLWIR p-on-n device technology on LPE-grown MCT has now been extended to the MWIR spectral range. A comparison of results from n-on-p and p-on-n MWIR MCT planar photodiode arrays is presented. Operating temperatures of 160 K and higher, in conjunction with low defect density and excellent thermal sensitivity (NETD) are attained. The results achieved for LPE MWIR are compared to MBE MWIR data. For both the cost-efficient production of MWIR single color MCT detectors, as well as 3rd generation multicolor MCT detectors, AIM makes use of MBE growth of MCT on large-area GaAs substrates. The now-available AIM MWIR single color MBE MCT detectors grown on GaAs are qualified, delivered, and have reached a maturity fully meeting customers' requirements. Representing AIM's multicolor detector development, latest test results on a 640x512 pixels with a 20 μm pitch design will be presented. The MWIR/MWIR diodes demonstrate high QE, very low color cross talk, and excellent NETD in conjunction with low defect densities.

  2. Use of a vacuum-planar photodiode to drive an electro-optic Q switch directly.

    PubMed

    Stankov, K A; Milev, I Y

    1991-12-20

    A vacuum photodiode was used to drive a Pockels cell directly in an optical-feedback arrangement. This technique was used to achieve Q switching and a single-longitudinal-mode operation in a flash-lamp-pumped Nd:YAG laser. Synchronization within 2 ns with an external short-pulse laser source was demonstrated.

  3. Recent Advances in Ultra-High-Speed Waveguide Photodiodes for Optical Communication Systems

    NASA Astrophysics Data System (ADS)

    Makita, Kikuo; Shiba, Kazuhiro; Nakata, Takeshi; Mizuki, Emiko; Watanabe, Sawaki

    This paper describes the recent advances in semiconductor photodiodes for use in ultra-high-speed optical systems. We developed two types of waveguide photodiodes (WG-PD) — an evanescently coupled waveguide photodiode (EC-WG-PD) and a separated-absorption-and-multiplication waveguide avalanche photodiode (WG-APD). The EC-WG-PD is very robust under high optical input operation because of its distribution of photo current density along the light propagation. The EC-WG-PD simultaneously exhibited a high external quantum efficiency of 70% for both 1310 and 1550nm, and a wide bandwidth of more than 40GHz. The WG-APD, on the other hand, has a wide bandwidth of 36.5GHz and a gain-bandwidth product of 170GHz as a result of its small waveguide mesa structure and a thin multiplication layer. Record high receiver sensitivity of -19.6dBm at 40Gbps was achieved. Additionally, a monolithically integrated dual EC-WG-PD for differential phase shift-keying (DPSK) systems was developed. Each PD has equivalent characteristics with 3-dB-down bandwidth of more than 40GHz and external quantum efficiency of 70% at 1550nm.

  4. 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.

  5. Temperature-Dependent Detectivity of Near-Infrared Organic Bulk Heterojunction Photodiodes.

    PubMed

    Wu, Zhenghui; Yao, Weichuan; London, Alexander E; Azoulay, Jason D; Ng, Tse Nga

    2017-01-18

    Bulk heterojunction photodiodes are fabricated using a new donor-acceptor polymer with a near-infrared absorption edge at 1.2 μm, achieving a detectivity up to 10(12) Jones at a wavelength of 1 μm and an excellent linear dynamic range of 86 dB. The photodiode detectivity is maximized by operating at zero bias to suppress dark current, while a thin 175 nm active layer is used to facilitate charge collection without reverse bias. Analysis of the temperature dependence of the dark current and spectral response demonstrates a 2.8-fold increase in detectivity as the temperature was lowered from 44 to -12 °C, a relatively small change when compared to that of inorganic-based devices. The near-infrared photodiode shows a switching speed reaching up to 120 μs without an external bias. An application using our NIR photodiode to detect arterial pulses of a fingertip is demonstrated.

  6. Influence of hot-carrier luminescence from avalanche photodiodes on time-correlated photon detection.

    PubMed

    Ulu, G; Sergienko, A V; Unlü, M S

    2000-05-15

    We present the results of our time-resolved measurements of hot-carrier luminescence from passively quenched Geiger-mode avalanche photodiodes. In time-correlated photon-counting (TCPC) experiments, hot-carrier luminescence interferes overwhelmingly with the coincidence spectrum, which results in artifacts. This potential problem should be taken into account in setting up TCPC experiments.

  7. Characterization of silicon avalanche photodiodes for photon correlation measurements. 3: Sub-Geiger operation.

    PubMed

    Brown, R G; Daniels, M

    1989-11-01

    We continue examination of the photon correlation properties of silicon avalanche photodiodes operated in the single-photon counting mode by extending their operation from that of passive [Appl. Opt. 25, 4122-4126 (1986)] and active [Appl. Opt. 26, 2383-2389 (1987)] quenching to the sub-Geiger mode, with potential for high quantum efficiency and very low afterpulsing.

  8. 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.

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

    PubMed

    Aull, Brian

    2016-04-08

    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.

  10. 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.

  11. 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.

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

    SciTech Connect

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

    2016-07-15

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

  13. Enabling luminescence decay time-based sensing using integrated organic photodiodes.

    PubMed

    Sagmeister, Martin; Tschepp, Andreas; Kraker, Elke; Abel, Tobias; Lamprecht, Bernhard; Mayr, Torsten; Köstler, Stefan

    2013-07-01

    The use of organic photodiodes (OPDs) for measuring phosphorescent lifetimes of optochemical oxygen sensors is described. Phosphorescent indicators with lifetimes ranging from ∼5 to 60 μs have been studied using light-emitting diodes as the excitation source and organic photodiodes integrated into the sensor substrate for detection. A measurement system using an adjusted electronic circuitry to detect photocurrents in the nanoampere range is presented. The response behaviour of the organic photodiodes has been characterized, and it was found that a forward (positive) bias had to be applied in order to decrease the response time of the OPDs to a range suitable for phosphorescence decay time measurements. A modulation cutoff frequency of ∼100 kHz has been determined, corresponding to a response time of the organic photodiodes of 1.6 μs. Two sensor dyes have been characterized regarding their lifetimes upon exposure to 0-20% oxygen, and it was shown that results comparable to literature data and inorganic photodetectors can be achieved.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

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

    SciTech Connect

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

    2013-09-10

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

  20. Studies of High Performance Indium Gallium Arsenide Metal-Semiconductor Photodiodes.

    NASA Astrophysics Data System (ADS)

    Gao, Wei

    1995-01-01

    The purpose of this study is to achieve high speed and high responsivity metal-semiconductor-metal (MSM) photodiodes, which includes material growth, device design, fabrication, and testing. Liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) growth were used to grow high purity InGaAs layers. To obtain high purity InGaAs layers, rare-earth elements (Yb, Ga, and Er) were used during LPE growth. The rare-earth elements react strongly with donor impurities to purify the epitaxial layers, resulting in higher mobility, lower carrier concentration, and higher photoluminescence efficiency in the rare-earth doped melt grown InGaAs layer. Unfortunately, rare-earth elements have high impurity levels and hardly interact with acceptor impurities; thus, causing undesired deep levels. Both abrupt and digital superlattice InAlAs barrier enhancement InGaAs MSM photodiodes were grown by MBE. To improve the photoresponsivity, a transparent conductive material, cadmium tin oxide (CTO) was used as the MSM contacts. The CTO functions as a Schottky contact, an optical window and an anti-reflection coating. The Schottky barrier height, which is vitally important for MSM photodiodes, was studied with CTO, ITO, Au, Ti, and Pt on InAlAs using the Norde method. The CTO MSM photodiodes showed a factor of almost two improvement in responsivity over conventional Ti/Au MSM photodiodes. Abrupt barrier enhancement MSM photodiodes using CTO and Ti/Au electrodes demonstrated 3-dB bandwidths of 0.3 and 0.8 GHz, respectively. However, digital grading of the heterojunction facilitated better carrier extraction resulting in increased bandwidths of 1.3 and 7.1 GHz, respectively, for CTO and Ti/Au. It was demonstrated that CTO possesses a low resistivity, high transparency, and good Schottky barrier height, which makes CTO a very attractive transparent conductor suitable for optoelectronic applications. Lastly, four novel structures were proposed to improve the responsivity and the bandwidth of

  1. Photodiode Camera Measurement of Surface Strains on Tendons during Multiple Cyclic Tests

    NASA Astrophysics Data System (ADS)

    Chun, Keyoung Jin; Hubbard, Robert Philip

    The objectives of this study are to introduce the use of a photodiode camera for measuring surface strain on soft tissue and to present some representative responses of the tendon. Tendon specimens were obtained from the hindlimbs of canines and frozen to -70°C. After thawing, specimens were mounted in the immersion bath at a room temperature (22°C), preloaded to 0.13N and then subjected to 3% of the initial length at a strain rate of 2%/sec. In tendons which were tested in two blocks of seven repeated extensions to 3% strain with a 120 seconds wait period between, the surface strains were measured with a photodiode camera and near the gripped ends generally were greater than the surface strains in the middle segment of the tendon specimens. The recovery for peak load after the rest period was consistent but the changes in patterns of surface strains after the rest period were not consistent. The advantages of a photodiode measurement of surface strains include the followings: 1) it is a noncontacting method which eliminates errors and distortions caused by clip gauges or mechanical/electronic transducers; 2) it is more accurate than previous noncontact methods, e.g. the VDA and the high speed photographic method; 3) it is a fully automatic, thus reducing labor for replaying video tapes or films and potential errors from human judgement which can occur during digitizing data from photographs. Because the photodiode camera, employs a solid state photodiode array to sense black and white images, scan targets (black image) on the surface of the tendon specimen and back lighting system (white image), and stored automatically image data for surface strains of the tendon specimen on the computer during cyclic extensions.

  2. Computer-aided strategies for archive retrieval and sensitivity enhancement in the identification of drugs by photodiode array detection in high-performance liquid chromatography.

    PubMed

    Fell, A F; Clark, B J; Scott, H P

    1984-12-21

    An archive retrieval algorithm for high-performance liquid chromatography with UV detection (HPLC-UV) has been developed for the first time for the rapid identification of spectra acquired by rapid-scanning photodiode array detection in HPLC. The algorithm is based on a database of spectra (normalised with respect to area), inverse files of key spectral features, a selective search window, with parabolic weighting factors and least-squares comparison of test and retrieved spectra. The performance of the library search system is demonstrated with respect to a small library of solutes, including: cortisone acetate, ethynyl estradiol, ethisterone, progesterone; caffeine, theobromine, theophylline and 8-chlorotheophylline; morphine and diamorphine; and cycloserine. Since photodiode array detection operates in the domains of both wavelength and time, to generate a matrix of (A, lambda, t) data, the optimum conditions for sensitivity enhancement by ensemble averaging in these domains have been examined. At a given observation wavelength, increase in the detector bandwidth (or "diode bunching") yields a value of delta lambda which gives optimum sensitivity; this value is systematically related to the spectral bandwidth of the analyte. Sensitivity can also be optimised by varying the integration period in the time domain. Sensitivity can be further increased by combination of these instrumental optima, for which there is evidence of dependence on the particular instrument design. Response was found to be linear for detector bandwidths up to twice the optimum value. The comparative sensitivity of some commercially-available photodiode array detectors has been assessed relative to that of conventional detectors under strictly controlled conditions.

  3. Integration of a concentric five element InAIAs/InGaAs avalanche photodiode array in a stabilized bi-static optical assembly

    NASA Astrophysics Data System (ADS)

    Ferraro, Mike S.; Mahon, Rita; Rabinovich, William S.; Murphy, James L.; Freeman, Wade T.; Frawley, Steve; Goetz, Peter G.; Burris, Harris R.; Thomas, Linda M.; Clark, William R.; Waters, William D.; Vaccaro, Kenneth; Krejca, Brian; Mathieu, Barry M.

    2014-06-01

    In free space optical communication, photodetectors serve not only as communications receivers but as position sensitive detectors (PSD) for pointing, tracking, and stabilization. Typically, two separate detectors are 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 PSDs and as data communication receivers. This combined functionality allows for more flexibility and simplicity in optical assembly design without sacrificing the sensitivity and bandwidth performance of smaller, single element data receivers. This work presents a large area, five element concentric avalanche photodiode array rated for bandwidths beyond 1GHz with a measured carrier ionization ratio of approximately 0.2 at moderate APD gains. We discuss the integration of this array in a bi-static optical interrogator where it acts as a data receiver and provides position information for pointing and stabilization. In addition to front-end and digital electronics design, we also describe the optical assembly design and the development of a pointing and stabilization algorithm.

  4. 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

  5. Simultaneous three-dimensional tracking of individual signals from multi-trap optical tweezers using fast and accurate photodiode detection.

    PubMed

    Ott, Dino; Nader, S; Reihani, S; Oddershede, Lene B

    2014-09-22

    Multiple-beam optical traps facilitate advanced trapping geometries and exciting discoveries. However, the increased manipulation capabilities come at the price of more challenging position and force detection. Due to unrivaled bandwidth and resolution, photodiode based detection is preferred over camera based detection in most single/dual-beam optical traps assays. However, it has not been trivial to implement photodiode based detection for multiple-beam optical traps. Here, we present a simple and efficient method based on spatial filtering for parallel photodiode detection of multiple traps. The technique enables fast and accurate 3D force and distance detection of multiple objects simultaneously manipulated by multiple-beam optical tweezers.

  6. 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

  7. Synthesis of water-dispersible poly-l-lysine-functionalized magnetic Fe3O4-(GO-MWCNTs) nanocomposite hybrid with a large surface area for high-efficiency removal of tartrazine and Pb(II).

    PubMed

    Hu, Dan; Wan, Xiaodong; Li, Xiaohui; Liu, Jianguo; Zhou, Chunhua

    2017-03-07

    In this study, a novel, effective and environment-friendly methods was used to prepare poly-l-lysine (PLL)-functionalized magnetic Fe3O4-(GO-MWCNTs) hybrid composite with large surface area and abundant hydroxyl and amino groups. The as-prepared PLL-Fe3O4-(GO-MWCNTs) nanocomposite was systematically characterized by FT-IR, XRD, TGA, SEM, TEM, VSM and EDX. The PLL-Fe3O4-(GO-MWCNTs) hybrid composite exhibited excellent adsorption performance for the removal of a dye (tartrazine) and a heave metal (Pb(II)). The result showed that adsorption of Pb(II) reached equilibrium in 30min and adsorption of tartrazine reached equilibrium in approximately 60min. Most importantly, PLL-Fe3O4-(GO-MWCNTs) hybrid possesses high adsorption capacity, rapid separation, and less time-consuming. The equilibrium adsorption capacity was 1038.42mgg(-1) for Pb(II) and 775.19mgg(-1) for tartrazine under the optimal conditions. These two pollutants removal were found to obey Langmuir adsorption model, while the kinetics of adsorption followed pseudo-second-order kinetic model. A possible adsorption mechanism has been proposed where the chelation between PLL and Pb(II) or electrostatic interaction between GO and tartrazine. These results demonstrated the potential applications of PLL-Fe3O4-(GO-MWCNTs) hybrid composite in deep-purification of polluted water. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Composite Scattering from the Electrically Very Large Ship-Sea Model Using the Hybrid High-Frequency Method

    NASA Astrophysics Data System (ADS)

    Luo, Wei; Zhang, Min; Zhou, Ping; Yin, Hong-Cheng

    2009-11-01

    A hybrid high-frequency method is proposed to analyze the bistatic electromagnetic scattering of the ship target on a very large two-dimensional randomly rough sea surface. The scattering of the ship-sea model is evaluated with the method of equivalent currents (MEC). The iterative physical optics method (IPO) is utilized to study the electromagnetic coupling effect caused by the hull and rough surface. The shadowing correction based on the Z-Buffer technology is introduced to eliminate the effects of the irrelevant scattering resources. The validity of the hybrid method is confirmed by the SAR simulation results and the scattering property of the ship-sea model is discussed.

  9. Increasing the response of PIN photodiodes to the ultraviolet

    NASA Technical Reports Server (NTRS)

    Burrous, C. N.; Whiting, E. E.

    1972-01-01

    Solid state device uses sapphire windows and avoids coatings which absorb ultraviolet radiation and ultimately alter detector geometry. Ultimate solution for ultraviolet response is geometry with maximum peripheral area and horizontal field structure to draw out photon induced current carriers.

  10. X ray and charged particle detection with CsI(Tl) layer coupled to a-Si:H photodiode layers

    NASA Astrophysics Data System (ADS)

    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 to 1000 microns 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.

  11. From hybrid swarms to swarms of hybrids

    USGS Publications Warehouse

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

    2014-01-01

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

  12. Photoelectric characteristics of an inverse U-shape buried doping design for crosstalk suppression in pinned photodiodes

    NASA Astrophysics Data System (ADS)

    Chen, Cao; Bing, Zhang; Xin, Li; Longsheng, Wu; Junfeng, Wang

    2014-11-01

    A design of an inverse U-shape buried doping in a pinned photodiode (PPD) of CMOS image sensors is proposed for electrical crosstalk suppression between adjacent pixels. The architecture achieves no extra fill factor consumption, and proper built-in electric fields can be established according to the doping gradient created by the injections of the extremely low P-type doping buried regions in the epitaxial layer, causing the excess electrons to easily drift back to the photosensitive area rarely with a diffusion probability; the overall junction capacitance and photosensitive area extensions for a full well capacity (FWC) and internal quantum efficiency (IQE) improving are achieved by the injection of a buried N-type doping. By considering the image lag issue, the process parameters of all the injections have been precisely optimized. Optical simulation results based on the finite difference time domain method show that compared to the conventional PPD, the electrical crosstalk rate of the proposed architecture can be decreased by 60%-80% at an incident wavelength beyond 450 nm, IQE can be clearly improved at an incident wavelength between 400 and 600 nm, and the FWC can be enhanced by 107.5%. Furthermore, the image lag performance is sustained to a perfect low level. The present study provides important guidance on the design of ultra high resolution image sensors.

  13. Generation-recombination effects on dark currents in CdTe-passivated midwave infrared HgCdTe photodiodes

    NASA Astrophysics Data System (ADS)

    Jozwikowska, A.; Jozwikowski, K.; Antoszewski, J.; Musca, C. A.; Nguyen, T.; Sewell, R. H.; Dell, J. M.; Faraone, L.; Orman, Z.

    2005-07-01

    The effect of an abrupt CdTe /HgCdTe passivation heterointerface on generation recombination and dark currents in n-on-p midwave infrared photodiodes with 5.2-μm cut-off wavelength has been investigated. Experimentally, it was observed that the zero-bias-dynamic resistance, R0, at low temperatures scales with the perimeter of the n-on-p junction, rather than with the junction area, suggesting that surface effects are dominant. The diode current-voltage characteristics at low temperatures indicate significant contributions from tunneling effects, which is the dominant leakage current mechanism for reverse bias greater than approximately 30mV. These two observations suggest that the region where the junction terminates at the CdTe /HgCdTe abrupt interface is responsible for the above effects. A two-dimensional model has been developed to investigate the dark current mechanisms in the vicinity of the junction termination at CdTe /HgCdTe interface, which also takes into account the effect of dislocations on generation-recombination processes. Calculated profiles of the energy bands and electric field along different cross sections of the photodiode indicate that the electric field achieves a maximum value of the order of mid -105V/cm in the region where the junction terminates at the CdTe /HgCdTe interface. The presence of such a high localized electric field in this area decreases the ionization energy of trap levels in the band gap and, hence, increases efficiency of the Shockley-Read-Hall generation-recombination processes. In addition to diffusion, generation recombination, and trap-assisted tunneling mechanisms, the calculations of dynamic resistance include Poole-Frenkel and phonon-trap-assisted tunneling effects. The best fit to the zero bias dynamic resistance versus temperature results has been obtained using an aerial dislocation density in the bulk of the HgCdTe layer equal to 106cm-2. Although the direct band-to-band tunneling and impact ionization

  14. Optimisation on the two-layer stack gamma detectors of CsI(Tl) coupled with a pin photodiode for non-destructive testing.

    PubMed

    Bai, Jin Hyoung; Whang, Joo Ho

    2011-07-01

    This paper proposed the two-layer stack scintillator-coupled photodiode detector to improve the measurement accuracy of the gamma-ray scanning. Both MCNPX and DETECT97 code were used to design the detector. The two manufactured two-layer stack gamma detectors were used to measure the density profile of the distillation column of the radiographic non-intrusive process diagnostic area. To compare the measurement accuracy of the density profile through the non-destructive transmission test, the relative error of the four fluids used for the process diagnostics was analysed. To summarise the measurement results with regard to the relative error of the NaI(Tl) detector and the manufactured detector by material as well as the total relative error, the total relative error of the NaI(Tl) detector was about 15.7 %, whereas that of the two-layer stack CsI(Tl) with photodiode detectors were about 5 %. This paper confirmed that the measurement accuracy of the detector proposed was improved by about three times as compared with the NaI(Tl) detector mostly used for non-destructive testing.

  15. Cooled photodiodes based on a type-II single p-InAsSbP/ n-InAs heterostructure

    NASA Astrophysics Data System (ADS)

    Il'inskaya, N. D.; Karandashev, S. A.; Latnikova, N. M.; Lavrov, A. A.; Matveev, B. A.; Petrov, A. S.; Remennyi, M. A.; Sevost'yanov, E. N.; Stus', N. M.

    2013-09-01

    Analysis of current-voltage and spectral characteristics of photodiodes based on a single p-InAsSbP/ n-InAs heterostructure formed on a heavily doped n +-InAs substrate ( n + ˜ 1018 cm-3) is presented. It is shown that, at low temperatures (77 < T < 190 K), the generation-recombination current flow mechanism typical of p-i-n diodes dominates. Expected parameters of the photodiode that can be obtained using these heterostructures are presented.

  16. Performance of InGaAs/InP Avalanche Photodiodes as Gated-Mode Photon Counters.

    PubMed

    Ribordy, G; Gautier, J D; Zbinden, H; Gisin, N

    1998-04-20

    We investigate the performance of separate absorption multiplication InGaAs/InP avalanche photodiodes as single-photon detectors for 1.3- and 1.55-mum wavelengths. First we study afterpulses and choose experimental conditions to limit this effect. Then we compare the InGaAs/InP detector with a germanium avalanche photodiode; the former shows a lower dark-count rate. The effect of operating temperature is studied for both wavelengths. At 173 K and with a dark-count probability per gate of 10(-4), detection efficiencies of 16% for 1.3 mum and 7% for 1.55 mum are obtained. Finally, a timing resolution of less than200 ps is demonstrated.

  17. HgCdTe avalanche photodiode detectors for airborne and spaceborne lidar at infrared wavelengths.

    PubMed

    Sun, Xiaoli; Abshire, James B; Beck, Jeffrey D; Mitra, Pradip; Reiff, Kirk; Yang, Guangning

    2017-07-10

    We report results from characterizing the HgCdTe avalanche photodiode (APD) arrays developed for lidar at infrared wavelengths by using the high density vertically integrated photodiodes (HDVIP(®)) technique. The results show >90% quantum efficiencies between 0.8 μm and the cut-off wavelength, >600 APD gain, near unity excess noise factor, 6-10 MHz electrical bandwidth and <0.5 fW/Hz(1/2) noise equivalent power (NEP). The detectors provide linear analog output with a dynamic range of 2-3 orders of magnitude at a fixed APD gain without averaging, and over 5 orders of magnitude by adjusting the APD gain settings. They have been used successfully in airborne CO2 and CH4 integrated path differential absorption (IPDA) lidar as precursors for use in space lidar.

  18. An InN/InGaN/GaN nanowire array guided wave photodiode on silicon

    NASA Astrophysics Data System (ADS)

    Hazari, Arnab; Zunaid Baten, Md.; Yan, Lifan; Millunchick, Joanna M.; Bhattacharya, Pallab

    2016-11-01

    The III-nitride nanowire heterostructure arrays with multiple InN disk light absorbing regions have been grown by plasma-assisted molecular beam epitaxy on (001)Si substrates, and guided wave photodiodes have been fabricated and characterized. The spectral photocurrent of the devices has been measured under reverse bias, and the data exhibit distinct shoulders in the range of 0.69-3.2 eV (0.39-1.8 μm). The estimated responsivity at a wavelength of 1.3 μm is 0.2 A/W. The nanowire photodiode response was also measured with an excitation at one facet provided by an edge-emitting laser fabricated with the same nanowire array and emitting at 1.3 μm.

  19. Pinch-off voltage modeling for CMOS image pixels with a pinned photodiode structure

    NASA Astrophysics Data System (ADS)

    Chen, Cao; Bing, Zhang; Longsheng, Wu; Xin, Li; Junfeng, Wang

    2014-07-01

    A novel analytical model of pinch-off voltage for CMOS image pixels with a pinned photodiode structure is proposed. The derived model takes account of the gradient doping distributions in the N buried layer due to the impurity compensation formed by manufacturing processes; the impurity distribution characteristics of two boundary PN junctions located in the region for particular spectrum response of a pinned photodiode are quantitative analyzed. By solving Poisson's equation in vertical barrier regions, the relationships between the pinch-off voltage and the corresponding process parameters such as peak doping concentration, N type width and doping concentration gradient of the N buried layer are established. Test results have shown that the derived model features the variations of the pinch-off voltage versus the process implant conditions more accurately than the traditional model. The research conclusions in this paper provide theoretical evidence for evaluating the pinch-off voltage design.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. The research and application of photodiodes for calibration of ultraviolet polarimeter UVP

    NASA Astrophysics Data System (ADS)

    Nevodovskiy, P. V.; Herayimchuk, M. D.; Vidmachenko, A. P.; Ivahiv, O. V.; Delets, A. S.

    2016-05-01

    To control of the main characteristics and for calibration of elements of the photodetector system of electro-optic equipment, necessary to use the etalon emitters. But they are very complex and expensive. Therefore for simplified of calibration and configuration of optical devices it is appropriate to use cheap and small in size, but specially selected light photodiodes. To do this on the basis of physical model of the block photodetector of board ultraviolet polarimeter (UVP) was created a special stand for selection and investigation of sources of electromagnetic radiation, which can be used for calibration of UVP and its individual units. It was developed a special methodology by which was done a lot of work on the study of different radiation sources, to identify the capabilities and features of the use of light photodiodes for calibration of electro-optical polarimeters.

  8. 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.

  9. HgCdTe Avalanche Photodiode Detectors for Airborne and Spaceborne Lidar at Infrared Wavelengths

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Abshire, James B.; Beck, Jeffrey D.; Mitra, Pradip; Reiff, Kirk; Yang, Guangning

    2017-01-01

    We report results from characterizing the HgCdTe avalanche photodiode (APD) sensorchip assemblies (SCA) developed for lidar at infrared wavelength using the high density vertically integrated photodiodes (HDVIP) technique. These devices demonstrated high quantum efficiency, typically greater than 90 between 0.8 micrometers and the cut-off wavelength, greater than 600 APD gain, near unity excess noise factor, 6-10 MHz electrical bandwidth and less than 0.5 fW/Hz(exp.1/2) noise equivalent power (NEP). The detectors provide linear analog output with a dynamic range of 2-3 orders of magnitude at a fixed APD gain without averaging, and over 5 orders of magnitude by adjusting the APD and preamplifier gain settings. They have been successfully used in airborne CO2 and CH4 integrated path differential absorption (IPDA) lidar as a precursor for space lidar applications.

  10. Spatial distortion correction and crystal identification for MRI-compatible position-sensitive avalanche photodiode-based PET scanners.

    PubMed

    Chaudhari, Abhijit J; Joshi, Anand A; Wu, Yibao; Leahy, Richard M; Cherry, Simon R; Badawi, Ramsey D

    2009-06-01

    Position-sensitive avalanche photodiodes (PSAPDs) are gaining widespread acceptance in modern PET scanner designs, and owing to their relative insensitivity to magnetic fields, especially in those that are MRI-compatible. Flood histograms in PET scanners are used to determine the crystal of annihilation photon interaction and hence, for detector characterization and routine quality control. For PET detectors that use PSAPDs, flood histograms show a characteristic pincushion distortion when Anger logic is used for event positioning. A small rotation in the flood histogram is also observed when the detectors are placed in a magnetic field. We first present a general purpose automatic method for spatial distortion correction for flood histograms of PSAPD-based PET detectors when placed both inside and outside a MRI scanner. Analytical formulae derived for this scheme are based on a hybrid approach that combines desirable properties from two existing event positioning schemes. The rotation of the flood histogram due to the magnetic field is determined iteratively and is accounted for in the scheme. We then provide implementation details of a method for crystal identification we have previously proposed and evaluate it for cases when the PET detectors are both outside and in a magnetic field. In this scheme, Fourier analysis is used to generate a lower-order spatial approximation of the distortion-corrected PSAPD flood histogram, which we call the 'template'. The template is then registered to the flood histogram using a diffeomorphic iterative intensity-based warping scheme. The calculated deformation field is then applied to the segmentation of the template to obtain a segmentation of the flood histogram. A manual correction tool is also developed for exceptional cases. We present a quantitative assessment of the proposed distortion correction scheme and crystal identification method against conventional methods. Our results indicate that our proposed methods lead to

  11. A prototype high-resolution animal positron tomograph with avalanche photodiode arrays and LSO crystals.

    PubMed

    Ziegler, S I; Pichler, B J; Boening, G; Rafecas, M; Pimpl, W; Lorenz, E; Schmitz, N; Schwaiger, M

    2001-02-01

    To fully utilize positron emission tomography (PET) as a non-invasive tool for tissue characterization, dedicated instrumentation is being developed which is specially suited for imaging mice and rats. Semiconductor detectors, such as avalanche photodiodes (APDs), may offer an alternative to photomultiplier tubes for the readout of scintillation crystals. Since the scintillation characteristics of lutetium oxyorthosilicate (LSO) are well matched to APDs, the combination of LSO and APDs seems favourable, and the goal of this study was to build a positron tomograph with LSO-APD modules to prove the feasibility of such an approach. A prototype PET scanner based on APD readout of small, individual LSO crystals was developed for tracer studies in mice and rats. The tomograph consists of two sectors (86 mm distance), each comprising three LSO-APD modules, which can be rotated for the acquisition of complete projections. In each module, small LSO crystals (3.7 x 3.7 x 12 mm3) are individually coupled to one channel within matrices containing 2x8 square APDs (2.6 x 2.6 mm2 sensitive area per channel). The list-mode data are reconstructed with a penalized weighted least squares algorithm which includes the spatially dependent line spread function of the tomograph. Basic performance parameters were measured with phantoms and first experiments with rats and mice were conducted to introduce this methodology for biomedical imaging. The reconstructed field of view covers 68 mm, which is 80% of the total detector diameter. Image resolution was shown to be 2.4 mm within the whole reconstructed field of view. Using a lower energy threshold of 450 keV, the system sensitivity was 350 Hz/MBq for a line source in air in the centre of the field of view. In a water-filled cylinder of 4.6 cm diameter, the scatter fraction at the centre of the field of view was 16% (450 keV threshold). The count rate was linear up to 700 coincidence counts per second. In vivo studies of anaesthetized rats

  12. Nanofabrication of Hybrid Optoelectronic Devices

    NASA Astrophysics Data System (ADS)

    Dibos, Alan Michael

    The material requirements for optoelectronic devices can vary dramatically depending on the application. Often disparate material systems need to be combined to allow for full device functionality. At the nanometer scale, this can often be challenging because of the inherent chemical and structural incompatibilities of nanofabrication. This dissertation concerns the integration of seemingly dissimilar materials into hybrid optoelectronic devices for photovoltaic, plasmonic, and photonic applications. First, we show that combining a single strip of conjugated polymer and inorganic nanowire can yield a nanoscale solar cell, and modeling of optical absorption and exciton diffusion in this device can provide insight into the efficiency of charge separation. Second, we use an on-chip nanowire light emitting diode to pump a colloidal quantum dot coupled to a silver waveguide. The resulting device is an electro-optic single plasmon source. Finally, we transfer diamond waveguides onto near-field avalanche photodiodes fabricated from GaAs. Embedded in the diamond waveguides are nitrogen vacancy color centers, and the mapping of emission from these single-photon sources is demonstrated using our on-chip detectors, eliminating the need for external photodetectors on an optical table. These studies show the promise of hybrid optoelectronic devices at the nanoscale with applications in alternative energy, optical communication, and quantum optics.

  13. 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}}) with noise of 375 e{sup {minus}} fwhm. When a four crystal / photodiode module is excited with a collimated line source of 511 key photons, the crystal of interaction is correctly identified 82% of the time. The misidentification rate can be greatly reduced and an 8{times}8 crystal / photodiode module constructed by using thicker depletion layer photodiodes or cooling to 0{degrees}C.

  14. Semi-Transparent ZnO-CuI/CuSCN Photodiode Detector with Narrow-Band UV Photoresponse.

    PubMed

    Yang, Zhi; Wang, Minqiang; Ding, Jijun; Sun, Zhongwang; Li, Le; Huang, Jin; Liu, Jing; Shao, Jinyou

    2015-09-30

    The ZnO homogeneous pn junction photodiode is quite difficult to fabricate due to the absence of stable p-type ZnO. So exploring reliable p-type materials is necessary to build a heterogeneous pn junction with n-type ZnO. Herein, we develop a simple and low-cost solution-processed method to obtain inorganic p-type CuI/CuSCN composite film with compact morphology, high conductivity, and low surface state. The improved performance of CuI/CuSCN composite film can be confirmed based on high-rectification ratio, responsivity, and open voltage of ZnO-CuI/CuSCN photodiode UV detectors. Moreover, photodiodes with novel top electrodes are investigated. Compared with commonly used Au and graphene/Ag nanowire (NWs) electrode, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) ( PSS) electrode prepared by Meyer rod-coating technique opens one route to obtain a semitransparent photodiode. The photodiode with PSS as the top electrode under reverse illumination has the highest photocurrent density due to higher UV transmittance of PSS transparent electrode compared with ITO glass. The low-energy consumption, and high responsivity, UV to visible rejection ratio and air stability make this ZnO-CuI/CuSCN photodiode quite promising in the UV-A detection field.

  15. Interdigitated microelectrode array-coupled bipolar semiconductor photodiode array (IMEA-PDA) microchip for on-chip electrochemiluminescence detection.

    PubMed

    Pal, Sukdeb; Kim, Min Jung; Tak, Yu Kyung; Kwon, Ho Taik; Song, Joon Myong

    2009-10-01

    This paper reports the design, fabrication and testing of a microchip wherein interdigitated microelectrode arrays (IMEA) were integrated with bipolar semiconductor photodiode array (PDA) chip to fabricate a highly compact embodiment for on-chip handling of solutions and electrochemiluminescence (ECL) detection. A 12 x 12 micro array of photodiodes, each coupled with an interdigitated microelectrode array (IMEA), an array of current amplifiers, and a photodiode element-addressing circuit were integrated into a single 2 x 2 cm² IC chip. Each photodiode had dimensions of 300 x 300 μm² and the photodiode-to-photodiode distance was 100 μm. The chip was successfully applied to the on-chip quantification of electro-chemiluminescing probe-labeled single stranded oligonucleotides. The minimum detectable limit at signal/noise ≥ 3 was found to be 5 x 10⁻¹⁴ moles of oligonucleotides with a sample volume as low as 5 microl (i.e., 10 fmole/μl). The attractive features of the developed IMEA-PDA microchip are that a plurality of samples can be analyzed simultaneously using a chip and that for a given sample the data can be averaged from values obtained from multiple, individually addressed pixels. These in turn bring in speed and statistical confidence in analysis. The IMEA-PDA microchip system has the potential to be used as a versatile and highly compact chemical analysis tool for chemical sensing and metrology applications.

  16. Voltage breakdown follower avoids hard thermal constraints in a Geiger mode avalanche photodiode.

    PubMed

    Viterbini, M; Nozzoli, S; Poli, M; Adriani, A; Nozzoli, F; Ottaviano, A; Ponzo, S

    1996-09-20

    A novel approach to single-photon detection by means of an avalanche photodiode is described and preliminary results obtained by implementation of a prototype are reported. The electronic circuit (breakdown voltage follower) avoids the use of complex temperature controls typically used with these devices, thus reducing system complexity and cost. Data obtained without any thermoregulation show the same behavior with respect to systems thermoregulated to within a few hundredths of a degree celsius.

  17. Recent advances in the detection of optical photons with silicon photodiodes

    NASA Astrophysics Data System (ADS)

    Lacaita, A.; Ghioni, M.; Zappa, F.; Ripamonti, G.; Cova, S.

    1993-03-01

    Geiger-mode avalanche photodiodes are interesting substitutes for conventional photomultiplier tubes in measurements of fast optical waveforms. In this paper we discuss the physical mechanisms involved in the detector operation and we clarify how these effects set a limit to the achievable timing performance. We show that a proper choice of the electric field profile is mandatory for the design of devices combining high quantum efficiency and timing resolution given by the ultimate transit time limit.

  18. 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.

  19. Organic photodiodes from homochiral l-proline derived squaraine compounds with strong circular dichroism.

    PubMed

    Schulz, Matthias; Mack, Majvor; Kolloge, Oliver; Lützen, Arne; Schiek, Manuela

    2017-03-08

    We suggest and explore a novel route towards organic photodetectors sensitive to the circular polarization state of light. For this, we insert fullerene-blended thin films of homochiral squaraine compounds acting as a highly circular dichroic active layer into conventional bulk hetero-junction photodiodes. Initially, we discuss steady-state characterization of photodiodes with unpolarized light. The homochiral, l-proline derived squaraine compounds are obtained via a chiral pool synthesis in sizable quantities. The aggregation behavior of the two compounds with varying side chain length is complex. They exhibit H-type spectral signatures only in colloidal solution, and both H- and J-type features with large splitting in neat and fullerene-blended thin films. We probe strong excitonic circular dichroism for both aggregate species, showing the most competitive dissymmetry factors up to -0.055 in fullerene-blended thin films. We vary the blend ratio and layer thickness of such active layers in the photodiodes. The device performance is in all cases limited by a low fill factor which is accompanied by a voltage-dependent photocurrent. Current-voltage measurements show light intensity dependent characteristics, which are S-shaped, contrary to our expectations, only for thin active layers independent of the blend ratio. The external quantum efficiency is in some cases extraordinarily high, exceeding 100 percent in the blue spectral range under modest reverse bias voltages for thin, fullerene-rich devices. However, the most promising are the devices with thick, donor-rich layers defined by a spectral overlap of the strongest photocurrent response and the maximum circular dichroism within the green spectral range. Thus, we demonstrate the feasibility of combining photodiode functionality and strong circular dichroism as intrinsic material properties.

  20. Vacuum photodiode detector array for broadband UV detection in a tokamak plasma.

    PubMed

    Zweben, S J; Menyuk, C R; Taylor, R J

    1979-08-01

    An array of vacuum photodiode detectors has been used to monitor discharge equilibrium, stability, and cleanliness in the Macrotor tokamak. These detectors use the photoelectric effect on small tungsten plates to measure UV emission in the band lambda approximately 200-1200 angstroms, and so are sensitive mainly to impurity line radiation in Macrotor. The response of this system to controlled impurity contamination experiments and to disruptions is described. The design, construction, and background problems associated with these detectors are discussed in detail.

  1. Feasibility study of an avalanche photodiode readout for a high resolution PET with nsec time resolution

    SciTech Connect

    Schmelz, C.; Ziegler, S.; Bradbury, S.M.; Holl, I.; Lorenz, E.; Renker, D.

    1995-08-01

    A feasibility study for a high resolution positron emission tomograph, based on 9.5 x 4 x 4 mm{sup 3} LSO crystals viewed by 3 mm diameter avalanche photodiodes, has been carried out. Using a Na{sup 22} source the authors determined a spatial resolution of 2.3 {+-} 0.1 mm, an energy resolution around 15 % and a time resolution of 2.6 nsec. Possible configurations for larger scale tests and a tomograph are given.

  2. 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.

  3. High sensitivity InAs photodiodes for mid-infrared detection

    NASA Astrophysics Data System (ADS)

    Ng, Jo Shien; Zhou, Xinxin; Auckloo, Akeel; White, Benjamin; Zhang, Shiyong; Krysa, Andrey; David, John P. R.; Tan, Chee Hing

    2016-10-01

    Sensitive detection of mid-infrared light (2 to 5 μm wavelengths) is crucial to a wide range of applications. Many of the applications require high-sensitivity photodiodes, or even avalanche photodiodes (APDs), with the latter generally accepted as more desirable to provide higher sensitivity when the optical signal is very weak. Using the semiconductor InAs, whose bandgap is 0.35 eV at room temperature (corresponding to a cut-off wavelength of 3.5 μm), Sheffield has developed high-sensitivity APDs for mid-infrared detection for one such application, satellite-based greenhouse gases monitoring at 2.0 μm wavelength. With responsivity of 1.36 A/W at unity gain at 2.0 μm wavelength (84 % quantum efficiency), increasing to 13.6 A/W (avalanche gain of 10) at -10V, our InAs APDs meet most of the key requirements from the greenhouse gas monitoring application, when cooled to 180 K. In the past few years, efforts were also made to develop planar InAs APDs, which are expected to offer greater robustness and manufacturability than mesa APDs previously employed. Planar InAs photodiodes are reported with reasonable responsivity (0.45 A/W for 1550 nm wavelength) and planar InAs APDs exhibited avalanche gain as high as 330 at 200 K. These developments indicate that InAs photodiodes and APDs are maturing, gradually realising their potential indicated by early demonstrations which were first reported nearly a decade ago.

  4. Effect of nitride chemical passivation of the surface of GaAs photodiodes on their characteristics

    NASA Astrophysics Data System (ADS)

    Kontrosh, E. V.; Lebedeva, N. M.; Kalinovskiy, V. S.; Soldatenkov, F. Yu; Ulin, V. P.

    2016-11-01

    Characteristics of GaAs photodiodes have been studied before and after the chemical nitridation of their surface in hydrazine sulfide solutions, which leads to substitution of surface As atoms with N atoms to give a GaN monolayer. The resulting nitride coatings hinder the oxidation of GaAs in air and provide a decrease in the density of surface states involved in recombination processes. The device characteristics improved by nitridation are preserved during a long time.

  5. The research of multi-alkali vacuum photodiode on heating and illuminating

    NASA Astrophysics Data System (ADS)

    Fu, Rongguo; Yang, Liu; Wang, Guiyuan; Wei, Yifang; Wang, Kun

    2016-10-01

    A novel concept for solar cell technology, photon-enhanced thermionic emission (PETE), was proposed for harvesting photonic and thermionic energy simultaneously. Researches show that the conversion efficiency of PETE is pretty high, calculated efficiencies for idealized devices can be above 50%, which is exceed the theoretical limits of single-junction photovoltaic cells. To explore whether the vacuum device can exhibit good performance under the conditions that combines illumination and heating, a multi-alkali vacuum photodiode is used as a quantum and thermal energy converter. The band gap of multi-alkali cathode is 1.1eV and the multi-alkali photocathode is employed at temperature below 350K.The current-voltage characteristic curve is measured under two different temperature conditions, so is the power-voltage curve. And the conversion efficiency of the multi-alkali vacuum photodiode is also calculated on the basis of experiment data. The experiment results show that the power converted by a heated and illuminated condition is greater than that obtained under illumination at room temperature or heating without illumination. The conversion efficiency of the multi-alkali vacuum photodiode is higher than that not be heated. This paper shows that the multi-alkali vacuum device presents better performance under the combined conditions. Although the power production and conversion efficiency are not very high in this research, the experiment demonstrates how the two forms of quantum and thermal of solar energy can be simultaneously utilized.

  6. Vertical solar blind Schottky photodiode based on homoepitaxial Ga2O3 thin film

    NASA Astrophysics Data System (ADS)

    Alema, Fikadu; Hertog, Brian; Osinsky, Andrei V.; Mukhopadhyay, Partha; Toporkov, Mykyta; Schoenfeld, Winston V.; Ahmadi, Elaheh; Speck, James

    2017-02-01

    High quality germanium doped β-Ga2O3 epitaxial film was grown by PMBE technique and fabricated into a vertical type Schottky photodiode with a Pt/nGa2O3/n+Ga2O3(010) structure. The photodiode exhibited excellent rectifying characteristics with a turn on voltage 1V and near zero bias leakage current 100 fA. The photoresponse measurement showed a true solar blind sensitivity with cutoff wavelength 260 nm and an out of band rejection ratio of 104. A maximum responsivity of 0.09 A/W at 230 nm was measured at zero bias, corresponding to an external quantum efficiency of 52 %. The time response of the photovoltaic diode is in the millisecond range and has no long-time decay component which is very common in the MSM photoconductive wide bandgap devices. The photodiode performance remains stable up to 300°C, suggesting its potential use for high temperature applications.

  7. Multimodal Photodiode and Phototransistor Device Based on Two-Dimensional Materials.

    PubMed

    Namgung, Seon; Shaver, Jonah; Oh, Sang-Hyun; Koester, Steven J

    2016-11-22

    With strong light-matter interaction in their atomically thin layered structures, two-dimensional (2D) materials have been widely investigated for optoelectronic applications such as photodetectors and photovoltaic devices. Depending on the aim of optoelectronic applications, different device structures have been employed. Lateral phototransistor structures have been employed for high optical gain, while vertical photodiode structures have been employed for fast response and low power operation. Herein, we demonstrate a multimodal photodetector platform based on 2D materials, combining both a phototransistor and a photodiode and taking the corresponding desirable characteristics from each structure within a single device. In this platform, a multilayered transition-metal dichalcogenide flake is transferred on top of metal electrodes, and a transparent gate electrode is employed. The channel region of the flake between electrodes operates as a phototransistor providing a high gain mode, while the electrode region in the same flake operates as a vertical Schottky photodiode providing a fast response mode. These modes can be dynamically selected by controlling the drain voltage and gate voltage.

  8. Optochemical sensor based on screenprinted fluorescent sensorspots surrounded by organic photodiodes for multianalyte detection

    NASA Astrophysics Data System (ADS)

    Kraker, E.; Lamprecht, B.; Haase, A.; Jakopic, G.; Abel, T.; Konrad, C.; Köstler, S.; Tscherner, M.; Stadlober, B.; Mayr, T.

    2010-08-01

    A compact, integrated photoluminescence based oxygen sensor, utilizing an organic light emitting device (OLED) as the light source and an organic photodiode (OPD) as the detection unit, is described. The detection system of the sensor array consists of an array of circular screen-printed fluorescent sensor spots surrounded by organic photodiodes as integrated fluorescence detectors. The OPD originates from the well-known Tang photodiode, consisting of a stacked layer of copper phthalocyanine (CuPc, p-type material) and perylene tetracarboxylic bisbenzimidazole (PTCBi, n-type material). An additional layer of tris-8-hydroxyquinolinatoaluminium (Alq3, n-type material) was inserted between the PTCBi layer and cathode. An ORMOCERR layer was used as encapsulation layer. For excitation an organic light emitting diode is used. The sensor spot and the detector are processed on the same flexible substrate. This approach not only simplifies the detection system by minimizing the numbers of required optical components - no optical filters have to be used for separating the excitation light and the luminescent emission-, but also has a large potential for low-cost sensor applications. The feasibility of the concept is demonstrated by an integrated oxygen sensor, indicating good performance. Sensor schemes for other chemical parameters are proposed.

  9. 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.

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

    PubMed

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

    2007-06-07

    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.

  11. Hg 1-x Cd xTe mid-wavelength infrared (MWIR) avalanche photodiode (APD) grown on Si substrate

    NASA Astrophysics Data System (ADS)

    Mallick, Shubhrangshu; Ghosh, Siddhartha; Velicu, Silviu; Zhao, Jun

    2007-09-01

    Photodetectors with high bandwidth and internal gain are required to detect highly attenuated optical signals for defense application and long distance communication. IR avalanche photodiodes (APDs) are best suited for this purpose due to their internal gain-bandwidth characteristics coupled with long range data transmission capability. For the past two decades, HgCdTe has been the most successful material for infrared photodetector applications. Recent advances in epitaxial growth techniques made possible the growth of advanced HgCdTe APD structures, but to the best of our knowledge all are grown on expensive substrates (e.g. CdZnTe, CdTe). We report for the first time HgCdTe-based MWIR (4.5 μm) p-i-n APD grown on Si substrate by molecular beam epitaxy (MBE). The devices were fabricated by 365nm UV photolithography and wet-etching technique. The diode had a junction area of 300μm diameter. The R 0A of the diode was 3 x 10 6 Ω-cm2 at 77K. Multiplication gains of 800 were measured at a reverse bias of 10 V in the linear operation regime. The gain increased exponentially as the reverse bias was increased, indicating that only one carrier is responsible for the impact ionization. Temperature dependence of the multiplication gain and of the breakdown voltage further confirms that avalanche multiplication dominates high reverse bias I-V characteristics.

  12. Development of an integrated four-channel fast avalanche-photodiode detector system with nanosecond time resolution

    NASA Astrophysics Data System (ADS)

    Li, Zhenjie; Li, Qiuju; Chang, Jinfan; Ma, Yichao; Liu, Peng; Wang, Zheng; Hu, Michael Y.; Zhao, Jiyong; Alp, E. E.; Xu, Wei; Tao, Ye; Wu, Chaoqun; Zhou, Yangfan

    2017-10-01

    A four-channel nanosecond time-resolved avalanche-photodiode (APD) detector system is developed at Beijing Synchrotron Radiation. It uses a single module for signal processing and readout. This integrated system provides better reliability and flexibility for custom improvement. The detector system consists of three parts: (i) four APD sensors, (ii) four fast preamplifiers and (iii) a time-digital-converter (TDC) readout electronics. The C30703FH silicon APD chips fabricated by Excelitas are used as the sensors of the detectors. It has an effective light-sensitive area of 10 × 10 mm2 and an absorption layer thickness of 110 μm. A fast preamplifier with a gain of 59 dB and bandwidth of 2 GHz is designed to readout of the weak signal from the C30703FH APD. The TDC is realized by a Spartan-6 field-programmable-gate-array (FPGA) with multiphase method in a resolution of 1ns. The arrival time of all scattering events between two start triggers can be recorded by the TDC. The detector has been used for nuclear resonant scattering study at both Advanced Photon Source and also at Beijing Synchrotron Radiation Facility. For the X-ray energy of 14.4 keV, the time resolution, the full width of half maximum (FWHM) of the detector (APD sensor + fast amplifier) is 0.86 ns, and the whole detector system (APD sensors + fast amplifiers + TDC readout electronics) achieves a time resolution of 1.4 ns.

  13. Waveguide-integrated vertical pin photodiodes of Ge fabricated on p+ and n+ Si-on-insulator layers

    NASA Astrophysics Data System (ADS)

    Ito, Kazuki; Hiraki, Tatsurou; Tsuchizawa, Tai; Ishikawa, Yasuhiko

    2017-04-01

    Vertical pin structures of Ge photodiodes (PDs) integrated with Si optical waveguides are fabricated by depositing Ge epitaxial layers on Si-on-insulator (SOI) layers, and the performances of n+-Ge/i-Ge/p+-SOI PDs are compared with those of p+-Ge/i-Ge/n+-SOI PDs. Both types of PDs show responsivities as high as 1.0 A/W at 1.55 µm, while the dark leakage current is different, which is consistent with previous reports on free-space PDs formed on bulk Si wafers. The dark current of the p+-Ge/i-Ge/n+-SOI PDs is higher by more than one order of magnitude. Taking into account the activation energies for dark current as well as the dependence on PD area, the dark current of the n+-Ge/i-Ge/p+-SOI PDs is dominated by the thermal generation of carriers via mid-gap defect levels in Ge, while for the p+-Ge/i-Ge/n+-SOI PDs, the dark current is ascribed to not only thermal generation but also other mechanisms such as locally formed conduction paths.

  14. Progress in MBE grown type-II superlattice photodiodes

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  15. Low Cost, High Performance Avalanche Photodiodes for Enabling High Sensitivity Bio-fluorescence Detection (First Year of a Two-year Program)

    DTIC Science & Technology

    2011-04-01

    Single-photon Detection Efficiency Avalanche Photodiode in Geiger - mode Operation. IEEE Phot. Tech. Lett. 2007, 19, 378–80. 3. Vurgaftman, I. I...Low Cost, High Performance Avalanche Photodiodes for Enabling High Sensitivity Bio-fluorescence Detection (First Year of a Two-year Program...Adelphi, MD 20783-1197 ARL-TR-5528 April 2011 Low Cost, High Performance Avalanche Photodiodes for Enabling High Sensitivity Bio-fluorescence

  16. Large format geiger-mode avalanche photodiode LADAR camera

    NASA Astrophysics Data System (ADS)

    Yuan, Ping; Sudharsanan, Rengarajan; Bai, Xiaogang; Labios, Eduardo; Morris, Bryan; Nicholson, John P.; Stuart, Gary M.; Danny, Harrison

    2013-05-01

    Recently Spectrolab has successfully demonstrated a compact 32x32 Laser Detection and Range (LADAR) camera with single photo-level sensitivity with small size, weight, and power (SWAP) budget for threedimensional (3D) topographic imaging at 1064 nm on various platforms. With 20-kHz frame rate and 500- ps timing uncertainty, this LADAR system provides coverage down to inch-level fidelity and allows for effective wide-area terrain mapping. At a 10 mph forward speed and 1000 feet above ground level (AGL), it covers 0.5 square-mile per hour with a resolution of 25 in2/pixel after data averaging. In order to increase the forward speed to fit for more platforms and survey a large area more effectively, Spectrolab is developing 32x128 Geiger-mode LADAR camera with 43 frame rate. With the increase in both frame rate and array size, the data collection rate is improved by 10 times. With a programmable bin size from 0.3 ps to 0.5 ns and 14-bit timing dynamic range, LADAR developers will have more freedom in system integration for various applications. Most of the special features of Spectrolab 32x32 LADAR camera, such as non-uniform bias correction, variable range gate width, windowing for smaller arrays, and short pixel protection, are implemented in this camera.

  17. 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.

  18. Study of evanescently-coupled and grating-assisted GaInAsSb photodiodes integrated on a silicon photonic chip.

    PubMed

    Gassenq, Alban; Hattasan, Nannicha; Cerutti, Laurent; Rodriguez, Jean Batiste; Tournié, Eric; Roelkens, Gunther

    2012-05-21

    In this paper we present GaInAsSb photodiodes heterogeneously integrated on SOI by BCB adhesive bonding for operation in the short-wave infrared wavelength region. Photodiodes using evanescent coupling between the silicon waveguide and the III-V structure are presented, showing a room temperature responsivity of 1.4A/W at 2.3 µm. Photodiode structures using a diffraction grating to couple from the silicon waveguide layer to the integrated photodiode are reported, showing a responsivity of 0.4A/W at 2.2 µm.

  19. Hybrid-integrated coherent receiver using silica-based planar lightwave circuit technology

    NASA Astrophysics Data System (ADS)

    Kim, Jong-Hoi; Choe, Joong-Seon; Choi, Kwang-Seong; Youn, Chun-Ju; Kim, Duk-Jun; Jang, Sun-Hyok; Kwon, Yong-Hwan; Nam, Eun-Soo

    2011-12-01

    A hybrid-integrated coherent receiver module has been achieved using flip-chip bonding technology, consisting of a silica-based 90°-hybrid planar lightwave circuit (PLC) platform, a spot-size converter integrated waveguide photodiode (SSC-WG-PD), and a dual-channel transimpedance amplifier (TIA). The receiver module shows error-free operation up to 40Gb/s and OSNR sensitivity of 11.5 dB for BER = 10-3 at 25 Gb/s.

  20. Evaluation of principal components analysis with high-performance liquid chromatography and photodiode array detection for the forensic differentiation of ballpoint pen inks.

    PubMed

    Kher, A A; Green, E V; Mulholland, M I

    2001-07-01

    Inks from seven black and eight blue ballpoint pens were separated by a high-performance liquid chromatography (HPLC) method utilizing a photodiode array detection (PDA). A classifier flowchart was designed for the chromatographic data based on the presence or absence of certain peaks at different wavelengths to qualitatively discriminate between the inks. The same data were quantitatively classified by principal components analysis (PCA) to estimate the separation between a pair of classes of ink samples. It was found that the black ballpoint pen inks were discriminated satisfactorily utilizing two-dimensional data of the peak areas and retention times at the optimum wavelengths. The blue pens were discriminated by analyzing the chromatographic data at four different wavelengths simultaneously with a cross-validated PCA. The results of this study indicated that HPLC-PDA coupled with chemometrics could make a powerful discriminating tool for the forensic chemist, especially when analyzing extensive and/or complex data.

  1. Optoelectronic measurement for parameters of high-speed flying objects based on laser screen and photodiode array

    NASA Astrophysics Data System (ADS)

    Zhao, Donge; Zhang, Bin; Liu, Ji; Xiao, Kai-jia; Wang, Lei

    2013-09-01

    The impacting or penetrating power of high-speed flying object can be evaluated by its mass and velocity, so the velocity and the mass are two key parameters. Here we present an optoelectronic measurement method for parameters of high-speed flying objects based on parallel laser screen and photodiode array. The system consists of two thin laser screens with parallel each other and certain distance, orthogonal two dimensional photodiode arrays, data acquisition module, control module and data transmission processing module. When the object flies through the thin screen, the incident light of some photodiodes at the corresponding position is blocked and the output states of the corresponding photodiodes are changed. The flying position, which can be used to correct the distance error, velocity and the overall dimension of the object are determined by high-speed sampling and storing all the output states of photodiode array at any sampling moment when the object flying through the thin screens. We employed a line-shaped laser diode and a Fresnel lens with long-focal-length and aberration-free to generate parallel laser screen. The high-speed large-amount parallel data sampling module is comprised of four FPGA-based boards with built-in FIFO buffer memory, and the control module is constructed by one FPGA board and a FLASH memory. Functions simulation and experiment results of the FPGA-based data acquisition storage and the LabVIEW-based data processing indicate that the method and the design are feasible.

  2. Hybrid Vehicles

    DTIC Science & Technology

    2008-12-08

    hybrid electric vehicles typically contain potentially hazardous levels of electrical voltage or current. It is important to protect the operators...60740. ITOP 2-2-607(1)41 is used for tracked vehicles. 13 TOP 2-1-003 08 December 2008 Hybrid electric vehicles often employ much more

  3. Application of the hybrid approach to the benchmark dose of urinary cadmium as the reference level for renal effects in cadmium polluted and non-polluted areas in Japan

    SciTech Connect

    Suwazono, Yasushi; Nogawa, Kazuhiro; Uetani, Mirei; Nakada, Satoru; Kido, Teruhiko; Nakagawa, Hideaki

    2011-02-15

    Objectives: The aim of this study was to evaluate the reference level of urinary cadmium (Cd) that caused renal effects. An updated hybrid approach was used to estimate the benchmark doses (BMDs) and their 95% lower confidence limits (BMDL) in subjects with a wide range of exposure to Cd. Methods: The total number of subjects was 1509 (650 men and 859 women) in non-polluted areas and 3103 (1397 men and 1706 women) in the environmentally exposed Kakehashi river basin. We measured urinary cadmium (U-Cd) as a marker of long-term exposure, and {beta}2-microglobulin ({beta}2-MG) as a marker of renal effects. The BMD and BMDL that corresponded to an additional risk (BMR) of 5% were calculated with background risk at zero exposure set at 5%. Results: The U-Cd BMDL for {beta}2-MG was 3.5 {mu}g/g creatinine in men and 3.7 {mu}g/g creatinine in women. Conclusions: The BMDL values for a wide range of U-Cd were generally within the range of values measured in non-polluted areas in Japan. This indicated that the hybrid approach is a robust method for different ranges of cadmium exposure. The present results may contribute further to recent discussions on health risk assessment of Cd exposure.

  4. Single and few photon avalanche photodiode detection process study

    NASA Astrophysics Data System (ADS)

    Blazej, Josef; Prochazka, Ivan

    2009-07-01

    We are presenting the results of the study of the Single Photon Avalanche Diode (SPAD) pulse response risetime and its dependence on several key parameters. We were investigating the unique properties of K14 type SPAD with its high delay uniformity of 200 μm active area and the correlation between the avalanche buildup time and the photon number involved in the avalanche trigger. The detection chip was operated in a passive quenching circuit with active gating. This setup enabled us to monitor the diode reverse current using an electrometer, a fast digitizing oscilloscope, and using a custom design comparator circuit. The electrometer reading enabled to estimate the photon number per detection event, independently on avalanche process. The avalanche build up was recorded on the oscilloscope and processed by custom designed waveform analysis package. The correlation of avalanche build up to the photon number, bias above break, photon absorption location, optical pulse length and photon energy was investigated in detail. The experimental results are presented. The existing solid state photon counting detectors have been dedicated for picosecond resolution and timing stability of single photon events. However, the high timing stability is maintained for individual single photons detection, only. If more than one photon is absorbed within the detector time resolution, the detection delay will be significantly affected. This fact is restricting the application of the solid state photon counters to cases where single photons may be guaranteed, only. For laser ranging purposes it is highly desirable to have a detector, which detects both single photon and multi photon signals with picoseconds stability. The SPAD based photon counter works in a purely digital mode: a uniform output signal is generated once the photon is detected. If the input signal consists of several photons, the first absorbed one triggers the avalanche. Obviously, for multiple photon signals, the

  5. Negative response of HgCdTe photodiode induced by nanosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Xu, Zuodong; Zhang, Jianmin; Lin, Xinwei; Shao, Bibo; Yang, Pengling

    2017-05-01

    Photodetectors' behavior and mechanism of transient response are still not understood very well, especially under high photon injection. Most of the researches on this topic were carried out with ultra-short laser pulse, whose pulse width ranged from femtosecond scale to picosecond scale. However, in many applications the durations of incident light are in nanosecond order and the light intensities are strong. To investigate the transient response characteristics and mechanisms of narrow-bandgap photovoltaic detectors under short laser irradiation, we performed an experiment on HgCdTe photodiodes. The n+-on-p type HgCdTe photodiodes in the experiment were designed to work in spectrum from 1.0μm to 3.0μm, with conditions of zero bias and room temperature. They were exposed to in-band short laser pulses with dwell time of 20 nanosecond. When the intensity of incident laser beam rose to 0.1J/cm2 order, the photodiodes' response characteristics turned to be bipolar from unipolar. A much longer negative response with duration of about 10μs to 100μs followed the positive light response. The amplitude of the negative response increased with the laser intensity, while the dwell time of positive response decreased with the laser intensity. Considering the response characteristics and the device structure, it is proposed that the negative response was caused by space charge effect at the electrodes. Under intense laser irradiation, a temperature gradient formed in the HgCdTe material. Due to the temperature gradient, the majority carriers diffused away from upper surface and left space charge at the electrodes. Then negative response voltage could be measured in the external circuit. With higher incident laser intensity, the degree of the space charge effect would become higher, and then the negative response would come earlier and show larger amplitude.

  6. Extremely Efficient Multiple Electron-hole Pair Generation in Carbon Nanotube Photodiodes

    NASA Astrophysics Data System (ADS)

    Gabor, Nathaniel

    2010-03-01

    The efficient generation of multiple electron-hole (e-h) pairs from a single photon could improve the efficiency of photovoltaic solar cells beyond standard thermodynamic limits [1] and has been the focus of much recent work in semiconductor nanomaterials [2,3]. In single walled carbon nanotubes (SWNTs), the small Fermi velocity and low dielectric constant suggests that electron-electron interactions are very strong and that high-energy carriers should efficiently generate e-h pairs. Here, I will discuss observations of highly efficient generation of e-h pairs due to impact excitation in SWNT p-n junction photodiodes [4]. To investigate optoelectronic transport properties of individual SWNT photodiodes, we focus a laser beam over the device while monitoring the electronic characteristics. Optical excitation into the second electronic subband E22 ˜ 2 EGAP leads to striking photocurrent steps in the device I-VSD characteristics that occur at voltage intervals of the band gap energy EGAP/ e. Spatially and spectrally resolved photocurrent combined with temperature-dependent studies suggest that these steps result from efficient generation of multiple e-h pairs from a single hot E22 carrier. We conclude that in the SWNT photodiode, a single photon with energy greater than 2EGAP is converted into multiple e-h pairs, leading to enhanced photocurrent and increased photo-conversion efficiency. [1] W. Shockley, and H. J. Queisser, Journal of Applied Physics 32, 510 (1961). [2] R. D. Schaller, and V. I. Klimov, Physical Review Letters 92 (18), 186601 (2004). [3] R. J. Ellingson, et al, Nano Letters, 5 (5), 865-871 (2005). [4] Nathaniel M. Gabor, Zhaohui Zhong, Ken Bosnick, Jiwoong Park, and Paul McEuen, Science, 325, 1367 (2009).

  7. 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.

  8. A Geiger-mode avalanche photodiode array for X-ray photon correlation spectroscopy.

    PubMed

    Johnson, I; Sadygov, Z; Bunk, O; Menzel, A; Pfeiffer, F; Renker, D

    2009-01-01

    X-ray photon correlation spectroscopy (XPCS) provides an opportunity to study the dynamics of systems by measuring the temporal fluctuations in a far-field diffraction pattern. A two-dimensional detector system has been developed to investigate fluctuations in the frequency range of several Hz to kHz. The X-ray detector system consists of a thin 100 microm scintillation crystal coupled to a Geiger-mode avalanche photodiode array. In this article the elements of the system are detailed and the detector for XPCS measurements is demonstrated.

  9. All-silicon spherical-Mie-resonator photodiode with spectral response in the infrared region.

    PubMed

    Garín, M; Fenollosa, R; Alcubilla, R; Shi, L; Marsal, L F; Meseguer, F

    2014-03-10

    Silicon is the material of choice for visible light photodetection and solar cell fabrication. However, due to the intrinsic band gap properties of silicon, most infrared photons are energetically useless. Here, we show the first example of a photodiode developed on a micrometre scale sphere made of polycrystalline silicon whose photocurrent shows the Mie modes of a classical spherical resonator. The long dwell time of resonating photons enhances the photocurrent response, extending it into the infrared region well beyond the absorption edge of bulk silicon. It opens the door for developing solar cells and photodetectors that may harvest infrared light more efficiently than silicon photovoltaic devices that are so far developed.

  10. Resonant normal-incidence separate-absorption-charge-multiplication Ge/Si avalanche photodiodes.

    PubMed

    Dai, Daoxin; Chen, Hui-Wen; Bowers, John E; Kang, Yimin; Morse, Mike; Paniccia, Mario J

    2009-09-14

    In this work the impedance of separate-absorption-charge-multiplication Ge/Si avalanche photodiodes (APD) is characterized over a large range of bias voltage. An equivalent circuit with an inductive element is presented for modeling the Ge/Si APD. All the parameters for the elements included in the equivalent circuit are extracted by fitting the measured S(22) with the genetic algorithm optimization. Due to a resonance in the avalanche region, the frequency response of the APD has a peak enhancement when the bias voltage is relatively high, which is observed in the measurement and agrees with the theoretical calculation shown in this paper.

  11. Multipixel silicon avalanche photodiode with ultralow dark count rate at liquid nitrogen temperature.

    PubMed

    Akiba, M; Tsujino, K; Sato, K; Sasaki, M

    2009-09-14

    Multipixel silicon avalanche photodiodes (Si APDs) are novel photodetectors used as silicon photomultipliers (SiPMs), or multipixel photon counter (MPPC), because they have fast response, photon-number resolution, and a high count rate; one drawback, however, is the high dark count rate. We developed a system for cooling an MPPC to liquid nitrogen temperature and thus reduce the dark count rate. Our system achieved dark count rates of <0.2 cps. Here we present the afterpulse probability, counting capability, timing jitter, and photon-number resolution of our system at 78.5 K and 295 K.

  12. InGaAs-InP avalanche photodiodes with dark current limited by generation-recombination.

    PubMed

    Zhao, Yanli; Zhang, Dongdong; Qin, Long; Tang, Qi; Wu, Rui Hua; Liu, Jianjun; Zhang, Youping; Zhang, Hong; Yuan, Xiuhua; Liu, Wen

    2011-04-25

    Separate absorption grading charge multiplication avalanche photodiodes (SAGCM APDs) are widely accepted in photon starved optical communication systems due to the presence of large photocurrent gain. In this work, we present a detailed analysis of dark currents of planar-type SAGCM InGaAs-InP APDs with different thicknesses of multiplication layer. The effect of the diffusion process, the generation-recombination process, the tunneling process and the multiplication process on the total leakage current is discussed. A new empirical formula has been established to predict the optimal multiplication layer thickness of SAGCM APDs with dark current limited by generation-recombination at multiplication gain of 8.

  13. 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.

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

    PubMed Central

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

    2012-01-01

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

  15. 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.

  16. 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.

  17. Detection probabilities for photon-counting avalanche photodiodes applied to a laser radar system.

    PubMed

    Henriksson, Markus

    2005-08-20

    Arrays of photon-counting avalanche photodiodes with time-resolved readout can improve the performance of three-dimensional laser radars. A comparison of the detection and false-alarm probabilities for detectors in linear mode and in Geiger mode is shown. With low background radiation their performance is comparable. It is shown that in both cases it will be necessary to process several laser shots of the same scene to improve detection and reduce the false-alarm rate. Additional calculations show that the linear mode detector is much better at detecting targets behind semitransparent obscurations such as vegetation and camouflage nets.

  18. Acquisition algorithm for direct-detection ladars with Geiger-mode avalanche photodiodes.

    PubMed

    Milstein, Adam B; Jiang, Leaf A; Luu, Jane X; Hines, Eric L; Schultz, Kenneth I

    2008-01-10

    An optimal algorithm for detecting a target using a ladar system employing Geiger-mode avalanche photodiodes (GAPDs) is presented. The algorithm applies to any scenario where a ranging direct detection ladar is used to determine the presence of a target against a sky background within a specified range window. A complete statistical model of the detection process for GAPDs is presented, including GAPDs that are inactive for a fixed period of time each time they fire. The model is used to develop a constant false alarm rate detection algorithm that minimizes acquisition time. Numerical performance predictions, simulation results, and experimental results are presented.

  19. 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.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Overbeck, Jay A.; Salisbury, Michael S.; Mark, Martin B.; Watson, Edward A.

    1995-11-01

    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 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.

  3. 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.

  4. 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.

  5. Autoconfocal transmission microscopy based on two-photon induced photocurrent of Si photodiodes

    PubMed Central

    Joo, Chulmin; Zhan, Chun; Li, Qing; Yazdanfar, Siavash

    2010-01-01

    We describe a simple, self-aligned confocal transmission microscopy technique based on two-photon induced photocurrents of silicon photodiodes. Silicon detectors produce photocurrents in quadratic dependence on incident intensity under the pulsed illumination of light with wavelengths longer than 1.2 μm. We exploit this nonlinear process to reject out-of-focus background and perform depth-sectioning microscopic imaging. We demonstrate a comparable background rejection capability of the technique to linear confocal detection, and present three-dimensional imaging in biological specimens. PMID:20664675

  6. Polymer based 3D photonic crystals applied on the surface of LEDs and photodiodes

    NASA Astrophysics Data System (ADS)

    Pudiš, Dušan; Goraus, Matej; Tłaczała, Marek; Gašo, Peter; Kováč, Jaroslav; Dawidowski, Wojciech; Jandura, Daniel; Å ušlik, Ľuboš; Durišová, Jana; Lettrichová, Ivana; Ściana, Beata

    2017-05-01

    Progress in nanotechnologies accelerated the polymer based photonics, where simple and cheap solutions often bring comparable and sometimes also novel interesting results. Good candidates are polymer photoresists and siloxane materials with unique mechanical and optical properties. We present laser lithography as efficient tool for fabrication of different three-dimensional (3D) structures embedded in polydimethylsiloxane (PDMS) membranes. Presented concept of PDMS based thin membranes with 3D structures works as an effective diffraction element for modification of radiation pattern diagram of light emitting diodes and changes also the angular photoresponse of photodiodes. All these results were demonstrated on two types of 3D structures - spheres arranged in cubic lattice and woodpile structure.

  7. Performance of a process, near infrared, photo-diode array based instrument for hydrocarbon fuels analysis

    SciTech Connect

    Workman, J. Jr; McDermott, L.

    1995-12-31

    The use of a 1024 element silicon photodiode-array (PDA) detector for the design of analytical spectrophotometers has been proposed since the early 1970s. The practical implementation of this technology did not occur for another decade. Traditional problems associated with interferometer-and moving dispersive grating based systems arise from mechanical misalignment and wear of critical moving parts with time. PDA technology represents the potential of increased measurement longevity due to a fixed grating and detector assembly. The purpose of this paper is to delineate the particulars of design and performance characteristics associated with using PDA-based spectrophotometer for hydrocarbon fuels analysis.

  8. 50-Gbit/s vertical illumination avalanche photodiode for 400-Gbit/s Ethernet systems.

    PubMed

    Nada, Masahiro; Yokoyama, Haruki; Muramoto, Yoshifumi; Ishibashi, Tadao; Matsuzaki, Hideaki

    2014-06-16

    50-Gbit/s error-free operation is demonstrated by a high-speed avalanche photodiode for the first time. The APD exhibits 3-dB bandwidth of 35 GHz and excellent receiver sensitivity of -10.8 dBm at a BER of 10(-12) against non-return to zero input optical signals. These results indicate our APD is promising for the systems with serial baud rate of 50 Gbit/s such as 400-Gbit/s Ethernet systems.

  9. 10μm thin transmissive photodiode produced by ALBA Synchrotron and IMB-CNM-CSIC

    NASA Astrophysics Data System (ADS)

    Cruz, C.; Jover-Manas, G.; Matilla, O.; Avila, J.; Juanhuix, J.; Pellegrini, G.; Quirion, D.; Rodriguez, J.

    2015-03-01

    Thin silicon photodiodes are common X-ray beam diagnosis devices at synchrotron facilities. Here we present a new device featuring an extremely thin layer that allows X-ray transmission over 90% for energies above 10 keV. The diode has a radiation-hard silicon junction with silicon dioxide passivation and a protective entrance window. These outstanding features make this device suited for diagnostic applications in X-ray synchrotron beamlines. Hereby preliminary results of X-ray transmission, responsivity and uniformity are presented.

  10. Magnetostriction measuring device based on an optical fiber sensor with an annular photodiode.

    PubMed

    de Manuel, V; Del Real, R P; Alonso, J; Guerrero, H

    2007-09-01

    A new simple and sensitive dilatometer to measure magnetostriction of ribbons has been developed, based on an optical fiber sensor using an annular photodiode. The optical fiber is used bidirectionally, both for emission and detection of light, simplifying the access to the ribbon under test. The working principle is based on the measurement by reflection of the longitudinal displacement of the ribbon end. For a Vitroperm amorphous ribbon of 100 mm length, 21 microm thickness, and 8.3 mm width, a displacement of 2.571 microm with a maximum uncertainty of 8 nm has been obtained.

  11. Triangular-barrier quantum rod photodiodes: Their fabrication and detector characteristics

    SciTech Connect

    Ohmori, M.; Kobayashi, Y.; Vitushinskiy, P.; Nakamura, S.; Kojima, T.; Sakaki, H.

    2014-02-24

    We have fabricated a GaAs-based triangular-barrier photodiode, in which self-assembled InGaAs quantum rods (Q-rods) are embedded in its barrier region. Transport study at 100 K has shown that electrons start to flow mainly through Q-rods when a bias is set above a threshold. Upon illumination, photo-generated holes are found to accumulate in the middle portion of Q-rods and efficiently lower the local barrier height, yielding the responsivity as high as 10{sup 5} A/W at the incident light of 1 fW.

  12. Self-scanned photodiode array - High performance operation in high dispersion astronomical spectrophotometry

    NASA Technical Reports Server (NTRS)

    Vogt, S. S.; Tull, R. G.; Kelton, P.

    1978-01-01

    A multichannel spectrophotometric detector system has been developed using a 1024 element self-scanned silicon photodiode array, which is now in routine operation with the high-dispersion coude spectrograph of the University of Texas McDonald Observatory 2.7-m telescope. Operational considerations in the use of such arrays for high precision and low light level spectrophotometry are discussed. A detailed description of the system is presented. Performance of the detector as measured in the laboratory and on astronomical program objects is described, and it is shown that these arrays are highly effective detectors for high dispersion astronomical spectroscopy.

  13. Trap-assisted tunneling in AlGaN avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Shao, Z. G.; Gu, Q. J.; Yang, X. F.; Zhang, J.; Kuang, Y. W.; Zhang, D. B.; Yu, H. L.; Hong, X. K.; Feng, J. F.; Liu, Y. S.

    2017-06-01

    We fabricated AlGaN solar-blind avalanche photodiodes (APDs) that were based on separate absorption and multiplication (SAM) structures. It was determined experimentally that the dark current in these APDs is rapidly enhanced when the applied voltage exceeds 52 V. Theoretical analyses demonstrated that the breakdown voltage at 52 V is mainly related to the local trap-assisted tunneling effect. Because the dark current is mainly dependent on the trap states as a result of modification of the lifetimes of the electrons in the trap states, the tunneling processes can be modulated effectively by tuning the trap energy level, the trap density, and the tunnel mass.

  14. 700-W diffusion-cooled large-area 40.68-MHz excited CO2 laser employing split-wave hybrid confocal resonator

    NASA Astrophysics Data System (ADS)

    Vitruk, Peter; Schemmer, James; Byron, Stan

    1998-09-01

    A novel non-waveguide, non-free-space CO2 laser resonator cavity, referred to as the split-wave hybrid (SWH) resonator, is described. Traditional resonator mirrors combined with two specially designed light reflecting electrode walls, which enclose the active medium, form the SWH resonator cavity. Light reflecting walls in the split-wave resonator act as wave-front-splitting mirrors in an interferometer, similar to a Fresnel double mirror or Lloyd mirror interferometer. Wave- front of the intra-cavity laser beam is significantly tilted with respect to the resonator walls, which facilitates lowest order mode selection in this resonator. Additionally, electrode wall surfaces contain discontinuities, which further enhances non-waveguide mode discrimination in the SWH resonator.

  15. Characterization of InGaAs avalanche photodiode arrays with varying geometries for free-space optical communication

    NASA Astrophysics Data System (ADS)

    Ferraro, Mike S.; Burris, Harris R.; Mahon, Rita; Rabinovich, William S.; Freeman, Wade T.; Murphy, James L.; Goetz, Peter G.; Moore, Christopher I.; Thomas, Linda M.; Clark, William R.; Waters, William D.; Vaccaro, Kenneth; Krejca, Brian D.

    2012-06-01

    Photodiode arrays are instrumental in providing pointing and tracking information for free space optical communication systems. Recent advances in the fabrication and development of low noise, high bandwidth avalanche photodiode (APD) arrays have enabled these devices to be used not only as position sensitive detectors (PSD) for tracking but also as communications receivers. In a collaborative effort with Optogration, Inc., the U.S. Naval Research Laboratory has developed avalanche photodiode arrays with three different geometries: a 3x3 square pixel array, a centered hexagonal pixel array, and a 5 pixel concentric array configuration with a center pixel and four periphery pixels. The characterization and performance of each array geometry will be described along with associated front-end and digital electronics. Design tradeoffs for maximizing the performance of a given array geometry will also be discussed.

  16. 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.

  17. 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.

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

    SciTech Connect

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

    2013-12-02

    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.

  19. Silicon-on-insulator shortwave infrared wavelength meter with integrated photodiodes for on-chip laser monitoring.

    PubMed

    Muneeb, M; Ruocco, A; Malik, A; Pathak, S; Ryckeboer, E; Sanchez, D; Cerutti, L; Rodriguez, J B; Tournié, E; Bogaerts, W; Smit, M K; Roelkens, G

    2014-11-03

    This paper demonstrates a very compact wavelength meter for on-chip laser monitoring in the shortwave infrared wavelength range based on an optimized arrayed waveguide grating (AWG) filter with an integrated photodiode array. The AWG response is designed to obtain large nearest neighbor crosstalk (i.e. large overlap) between output channels, which allows accurately measuring the wavelength of a laser under test using the centroid detection technique. The passive AWG is fabricated on a 220 nm silicon-on-insulator (SOI) platform and is combined with GaInAsSb-based photodiodes. The photodiodes are heterogeneously integrated on the output grating couplers of the AWG using DVS-BCB adhesive bonding. The complete device with AWG and detectors has a footprint of only 2 mm(2) while the measured accuracy and resolution of the detected wavelength is better than 20pm.

  20. Cross-Species Hybridization with Fusarium verticillioides Microarrays Reveals New Insights into Fusarium fujikuroi Nitrogen Regulation and the Role of AreA and NMR

    USDA-ARS?s Scientific Manuscript database

    In filamentous fungi, the GATA-type transcription factor AreA plays a major role in transcriptional activation of genes needed to utilize poor nitrogen sources. Previously we have shown that in Fusarium fujikuroi AreA also controls genes involved in biosynthesis of nitrogen-free secondary metabolit...