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  • 1.
    Ahmed, Rizwan
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Abbas, Shahid
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Electrical and Optical Characteristics of InP Nanowires based p-i-n Photodetectors2010Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Photodetectors are a kind of semiconductor devices that convert incoming light to an electrical signal. Photodetectors are classified based on their different structure, fabrication technology, applications and different sensitivity. Infrared photodetectors are widely used in many applications such as night vision, thermal cameras, remote temperature sensing, and medical diagnosis etc.

     

    All detectors have material inside that is sensitive to incoming light. It will absorb the photons and, if the incoming photons have enough energy, electrons will be excited to higher energy levels and if these electrons are free to move, under the effect of an external electric field, a photocurrent is generated.

     

    In this project Fourier Transform Infrared (FT-IR) Spectroscopy is used to investigate a new kind of photodiodes that are based on self-assembled semiconductor nanowires (NWs) which are grown directly on the substrate without any epi-layer. The spectrally resolved photocurrent (at different applied biases) and IV curves (in darkness and illumination) for different temperatures have been studied respectively. Polarization effects (at low and high Temperatures) have been investigated.  The experiments are conducted for different samples with high concentration of NWs as well as with lower concentration of NWs in the temperature range from 78 K (-195ºC) to 300 (27ºC). These photodiodes are designed to work in near infrared (NIR) spectral range.

     

    The results show that the NW photodetectors indeed are promising devices with fairly high break down voltage, change of photocurrent spectra with polarized light, low and constant reverse saturation current (Is). The impact of different polarized light on photocurrent spectra has been investigated and an attempt has been made to clarify the observed double peak of InP photocurrent spectrum. Our investigations also include a comparison to a conventional planar InP p-i-n photodetector.

     

    Fulltekst (pdf)
    FULLTEXT01
  • 2.
    Hussain, Laiq
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Pettersson, Håkan
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab).
    Wang, Q.
    Acreo Swedish ICT AB, Kista, Sweden.
    Karim, A.
    Acreo Swedish ICT AB, Kista, Sweden.
    Anderson, J.
    Acreo Swedish ICT AB, Kista, Sweden.
    Jafari, Mehrdad
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab).
    Song, J.
    Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, South Korea.
    Choi, W. J.
    Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, South Korea.
    Han, I. K.
    Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, South Korea.
    Lim, J. Y.
    Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, South Korea.
    SWIR-LWIR Photoluminescence from Sb-based Epilayers Grown on GaAs Substrates by using MBE2018Inngår i: Journal of the Korean Physical Society, ISSN 0374-4884, E-ISSN 1976-8524, Vol. 73, nr 11, s. 1604-1611Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Utilizing Sb-based bulk epilayers on large-scale low-cost substrates such as GaAs for fabricating infrared (IR) photodetectors is presently attracting significant attention worldwide. For this study, three sample series of GaAsxSb1−x, In1−xGaxSb, and InAsxSb1x with different compositions were grown on semi-insulating GaAs substrates by using molecular beam epitaxy (MBE) and appropriate InAs quantum dots (QDs) as a defect-reduction buffer layer. Photoluminescence (PL) signals from these samples were observed over a wide IR wavelength range from 2 μm to 12 μm in agreement with the expected bandgap, including bowing effects. In particular, interband PL signals from InAsxSb1−x and In1−xGaxSb samples even at room temperature show promising potential for IR photodetector applications.

    Fulltekst (pdf)
    fulltext
  • 3.
    Karimi, Mohammad
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS). Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Zeng, Xulu
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Witzigmann, Bernd
    Computational Electronics and Photonics Group and CINSaT, University of Kassel, Kassel, Germany.
    Samuelson, Lars
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Borgström, Magnus T.
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Pettersson, Håkan
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab). Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS). Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    High Responsivity of InP/InAsP Nanowire Array Broadband Photodetectors Enhanced by Optical Gating2019Inngår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 19, nr 12, s. 8424-8430Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High-performance photodetectors operating in the near-infrared (0.75−1.4 μm) and short-wave infrared (1.4−3.0 μm) portion ofthe electromagnetic spectrum are key components in many optical systems.Here, we report on a combined experimental and theoretical study of squaremillimeter array infrared photodetectors comprising 3 million n+−i−n+ In Pnanowires grown by MOVPE from periodically ordered Au seed particles. Thenominal i-segment, comprising 20 InAs0.40P0.60 quantum discs, was grown byuse of an optimized Zn doping to compensate the nonintentional n-doping.The photodetectors exhibit bias- and power-dependent responsivities reachingrecord-high values of 250 A/W at 980 nm/20 nW and 990 A/W at 532 nm/60nW, both at 3.5 V bias. Moreover, due to the embedded quantum discs, thephotoresponse covers a broad spectral range from about 0.70 to 2.5 eV, ineffect outperforming conventional single InGaAs detectors and dual Si/Gedetectors. The high responsivity, and related gain, results from a novel proposed photogating mechanism, induced by the complex charge carrier dynamics involving optical excitation and recombination in the quantum discs and interface traps, which reduces the electron transport barrier between the highly doped ncontact and the i-segment. The experimental results obtained are in perfect agreement with the proposed theoretical model and represent a significant step forward toward understanding gain in nanoscale photodetectors and realization of commercially viable broadband photon detectors with ultrahigh gain. © 2019 American Chemical Society.

  • 4.
    Karimi, Mohammad
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab). Solid State Physics and NanoLund, Department of Physics, Lund University, Lund, Sweden.
    Zeng, Zulu
    Solid State Physics and NanoLund, Department of Physics, Lund University, Lund, Sweden.
    Witzigmann, Bernd
    Computational Electronics and Photonics Group and CINSaT, University of Kassel, Germany.
    Samuelson, Lars
    Solid State Physics and NanoLund, Department of Physics, Lund University, Lund, Sweden.
    Borgström, Magnus T.
    Solid State Physics and NanoLund, Department of Physics, Lund University, Lund, Sweden.
    Pettersson, Håkan
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab). Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS). Solid State Physics and NanoLund, Department of Physics, Lund University, Lund, Sweden.
    Room temperature high responsivity SWIR/NIR photodetectors based on InAsP/InP NW array heterostructures2019Inngår i: Nanowire Week: Book of Abstracts, 2019, s. 188-188Konferansepaper (Fagfellevurdert)
  • 5.
    Nilsson, Carl Magnus
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligenta system (IS-lab).
    Carlsson, Jörgen
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Malmqvist, Lennart
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Persson, Willy
    Semtech Metallurgy AB, Lund, Sweden.
    Application of optical spectroscopy to paper production1999Inngår i: Optical measurement systems for industrial inspection / [ed] Malgorzata Kujawinska, Bellingham, Washington: SPIE - International Society for Optical Engineering, 1999, s. 318-325Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fluorescence from paper following excitation by either ultraviolet or visible light gives information on the chemical composition of the paper. This can be used for on-line monitoring of the paper during production. Such measurements can be performed non-intrusively at sampling rates high enough to give a sub-millimetre resolution at paper webs moving at velocities higher than 20 metres per second. Two types of fluorescence meters, operating at different wavelengths, have been constructed. Together with an optical speedometer they have been tested at newsprint producing paper mills. A fluorescence based method for scanning cross-directional newsprint profiles in the laboratory has been developed. From these measurements the relative shrinkage of the paper during drying can be calculated using time-frequency analysis.

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