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  • 1.
    Hussain, Laiq
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS). Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Karimi, Mohammad
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS). Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Berg, Alexander
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Jain, Vishal
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS). Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Borgström, Magnus T.
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Gustafsson, Anders
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Samuelson, Lars
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Pettersson, Håkan
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS). Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Defect-induced infrared electroluminescence from radial GaInP/AlGaInP quantum well nanowire array light- emitting diodes2017Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, nr 48, artikel-id 485205Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radial GaInP/AlGaInP nanowire array light-emitting diodes (LEDs) are promising candidates for novel high-efficiency solid state lighting due to their potentially large strain-free active emission volumes compared to planar LEDs. Moreover, by proper tuning of the diameter of the nanowires, the fraction of emitted light extracted can be significantly enhanced compared to that of planar LEDs. Reports so far on radial growth of nanowire LED structures, however, still point to significant challenges related to obtaining defect-free radial heterostructures. In this work, we present evidence of optically active growth-induced defects in a fairly broad energy range in vertically processed radial GaInP/AlGaInP quantum well nanowire array LEDs using a variety of complementary experimental techniques. In particular, we demonstrate strong infrared electroluminescence in a spectral range centred around 1 eV (1.2 μm) in addition to the expected red light emission from the quantum well. Spatially resolved cathodoluminescence studies reveal a patchy red light emission with clear spectral features along the NWs, most likely induced by variations in QW thickness, composition and barriers. Dark areas are attributed to infrared emission generated by competing defect-assisted radiative transitions, or to trapping mechanisms involving non-radiative recombination processes. Possible origins of the defects are discussed. © 2017 IOP Publishing Ltd

  • 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, 16425, Sweden.
    Karim, A.
    Acreo Swedish ICT AB, Kista, 16425, Sweden.
    Anderson, J.
    Acreo Swedish ICT AB, Kista, 16425, 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, 02792, South Korea.
    Choi, W. J.
    Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, 02792, South Korea.
    Han, I. K.
    Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, 02792, South Korea.
    Lim, J. Y.
    Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, 02792, South Korea.
    SWIR-LWIR Photoluminescence from Sb-based Epilayers Grown on GaAs Substrates by using MBE2018Ingår i: Journal of the Korean Physical Society, ISSN 0374-4884, E-ISSN 1976-8524, Vol. 73, nr 11, s. 1604-1611Artikel i tidskrift (Refereegranskat)
    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 InAsxSb1−x 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 ÎŒm to 12 ÎŒm 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. © 2018, The Author(s).

  • 3.
    Jain, Vishal
    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 Nano, Lund University, Lund, Sweden.
    Heurlin, Magnus
    Solid State Physics and Nano, Lund University, Lund, Sweden.
    Karimi, Mohammad
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab). Solid State Physics and Nano, Lund University, Lund, Sweden.
    Hussain, Laiq
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab). Solid State Physics and Nano, Lund University, Lund, Sweden.
    Aghaeipour, Mahtab
    Solid State Physics and Nano, Lund University, Lund, Sweden.
    Nowzari, Ali
    Solid State Physics and Nano, Lund University, Lund, Sweden.
    Berg, Alexander
    Solid State Physics and Nano, Lund University, Lund, Sweden.
    Nylund, Gustav
    Solid State Physics and Nano, Lund University, Lund, Sweden.
    Capasso, Federico
    Harvard University, Cambridge, United States of America.
    Samuelson, Lars
    Solid State Physics and Nano, Lund University, Lund, Sweden.
    Borgström, Magnus T.
    Solid State Physics and Nano, 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). Solid State Physics and Nano, Lund University, Lund, Sweden.
    Bias-dependent spectral tuning in InP nanowire-based photodetectors2017Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, nr 11, artikel-id 114006Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanowire array ensembles contacted in a vertical geometry are extensively studied and considered strong candidates for next generations of industrial scale optoelectronics. Key challenges in this development deal with optimization of the doping profile of the nanowires and the interface between nanowires and transparent top contact. Here we report on photodetection characteristics associated with doping profile variations in InP nanowire array photodetectors. Bias-dependent tuning of the spectral shape of the responsivity is observed which is attributed to a Schottky-like contact at the nanowire-ITO interface. Angular dependent responsivity measurements, compared with simulated absorption spectra, support this conclusion. Furthermore, electrical simulations unravel the role of possible self-gating effects in the nanowires induced by the ITO/SiOx wrap-gate geometry. Finally, we discuss possible reasons for the observed low saturation current at large forward biases.  

  • 4.
    Jain, Vishal
    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 the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Heurlin, Magnus
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Lindgren, David
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Nowzari, Ali
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Hussein, Laiq
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Wallentin, Jesper
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Capasso, Federico
    School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA.
    Borgström, Magnus T.
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Gustafsson, Anders
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Samuelson, Lars
    Solid State Physics and the Nanometer Structure Consortium, 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). Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Large area photodetectors based on InP NWs with InAs/InAsP QWs2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Focal plane arrays have a widespread use in infrared imaging, which often rely on cryogenic cooling to curtail the dark current level necessary for a reasonable signal-to-noise ratio. Quantum well (QW) infrared photodetectors are uniform over large areas, but suffer from a severe drawback related to the selection rules for intersubband absorption. An interesting alternative is self-assembled III-V nanowires offering a key advantage owing to the enhanced absorption by optical resonance effects and strain relaxation.We present electrical and optical results from large ensembles of n+-i-n+ InP NWs, axially grown on InP substrates with InAs/InAsP QWs embedded within the i-segment, designed for both interband and intersubband detection. The NWs are contacted in a vertical geometry using 50 nm SiO2 as the insulating layer and ITO as the top contact. We first investigate the crystal quality of the InAsP QWs grown in 180 nm diameter NWs, using PL, CL and TEM. To achieve more abrupt InAs/InAsP QWs, we grow 130 nm diameter NWs and deplete the In present in the Au catalysts. The effect of n-doping on the device performance is studied by fabricating two different NW geometries, with and without an n+-segment grown before the nominal i-segment in the NW. In addition, the position of the QWs within the i-segment is varied to further scrutinize effects related to doping and crystal structure. Finally, we report spectrally resolved photocurrent results from the QWs in the near-infrared region and discuss about the further developments needed for intersubband detection.

  • 5.
    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, Lund University, Lund, Sweden.
    Jain, Vishal
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab). Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Heurlin, Magnus
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Nowzari, Ali
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Hussain, Laiq
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS). Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Lindgren, David
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Stehr, Jan Eric
    Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Buyanova, Irina A.
    Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Gustafsson, Anders
    Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    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). Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Room-temperature InP/InAsP Quantum Discs-in-Nanowire Infrared Photodetectors2017Ingår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 17, nr 6, s. 3356-3362Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The possibility to engineer nanowire heterostructures with large bandgap variations is particularly interesting for technologically important broadband photodetector applications. Here we report on a combined study of design, fabrication, and optoelectronic properties of infrared photodetectors comprising four million n+–i–n+ InP nanowires periodically ordered in arrays. The nanowires were grown by metal–organic vapor phase epitaxy on InP substrates, with either a single or 20 InAsP quantum discs embedded in the i-segment. By Zn compensation of the residual n-dopants in the i-segment, the room-temperature dark current is strongly suppressed to a level of pA/NW at 1 V bias. The low dark current is manifested in the spectrally resolved photocurrent measurements, which reveal strong photocurrent contributions from the InAsP quantum discs at room temperature with a threshold wavelength of about 2.0 μm and a bias-tunable responsivity reaching 7 A/W@1.38 μm at 2 V bias. Two different processing schemes were implemented to study the effects of radial self-gating in the nanowires induced by the nanowire/SiOx/ITO wrap-gate geometry. Summarized, our results show that properly designed axial InP/InAsP nanowire heterostructures are promising candidates for broadband photodetectors. © 2017 American Chemical Society.

  • 6.
    Wang, Qin
    et al.
    Acreo 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).
    Hussein, Laiq
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Song, Jindong
    Center for Optoelectronic Convergence Systems, KIST (Korean Institute of Science and Technology), Seoul, South Korea.
    Choi, Won Jun
    Center for Optoelectronic Convergence Systems, KIST (Korean Institute of Science and Technology), Seoul, South Korea.
    Han, Il Ki
    Center for Optoelectronic Convergence Systems, KIST (Korean Institute of Science and Technology), Seoul, South Korea.
    Lee, Eun Hye
    Center for Optoelectronic Convergence Systems, KIST (Korean Institute of Science and Technology), Seoul, South Korea.
    Park, Suk In
    Center for Optoelectronic Convergence Systems, KIST (Korean Institute of Science and Technology), Seoul, South Korea.
    Lim, Ju Young
    Laser-IT Center, Korea Photonics Technology Institute, Seoul, South Korea.
    Karim, Amir
    Acreo ICT AB, Kista, Sweden.
    Andersson, Jan Y.
    Acreo ICT AB, Kista, Sweden.
    Pettersson, Håkan
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab).
    MWIR interband transitions in type-II (III) In(GaAl)Sb quantum dots2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work we present an alternative approach for realizing desired IR devices with appropriate operating wavelengths in the MWIR region utilizing In(GaAl)Sb quantum dots embedded in an InAs matrix grown by MBE. The QDs exhibit spatially indirect interband transitions in a type-II broken bandgap alignment, with a transition energy that can be tuned by bandgap and strain engineering utilizing either the quantum dot size or the incorporation of Ga or (GaAl) into the QDs. Furthermore, the growth of such QDs does not require sophisticated epitaxial designs needed for superlattices or quantum cascade structures regarding large numbers of alternating layers and very exact interfaces. The QD structures are expected to exhibit key advantages for IR devices e.g. higher operating temperature, lower power consumption, size, weight, and cost. The structural and composition properties of designed and grown In(GaAl)Sb QDs were characterized using AFM, SEM, TEM, and XRD. The corresponding optical properties, both in terms of absorption and emission, were analyzed and compared for selected QD samples before and after annealing at 650 °C.

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