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  • 1.
    Amin, Mohammed Nurul
    et al.
    Halmstad University, School of Information Technology. amin _ m 154@yahoo.com.
    Alam, Md. Obaidul
    Halmstad University, School of Information Technology. obai_ aust@yahoo.com.
    Landin, Lars
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Electrical and optical characteristics of Infrared Photodetectors based on InP nanowire2011In: 14th International Conference on Computer and Information Technology, ICCIT 2011, p. 629-634, article id 6164864Article in journal (Refereed)
    Abstract [en]

    High speed photodetectors are most sophisticated optoelectronic devices, because it has high photo sensitivity, and allow a large wavelength range of detection as a receiver from 750 nm to 1.3-1.55 μm in the optical communication system. Since the last decade, the electrical and optical characteristics of photodetectors have been investigated to improve their performance and price. We have worked on two different type of infrared photodetectors based on nanowire. One photodetector was p-n photodiode, and the other one was p-i-n structure. We investigated the detector performance at 77K-300K temperature corresponding with wavelength in darkness and under illumination as regarding breakdown voltage, sensitivity, and quantum efficiency. We have also compared the differences between the two photodetectors performance characteristics. © 2011 IEEE.

  • 2.
    Jain, Vishal
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Wallentin, Jesper
    Physics Department, Lund University, Lund, Sweden.
    Borgström, Magnus
    Physics department, Lund university, Lund, Sweden.
    Storm, Kristian
    Physics Department, Lund University, Lund, Sweden.
    Landin, Lars
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Wickert, Peter
    Sol Voltaics AB, Lund, Sweden.
    Capasso, Federico
    Harvard University, Cambridge, Massachusetts, USA.
    Samuelson, Lars
    Physics Department, Lund university, Lund, Sweden.
    Pettersson, Håkan
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    A comparative study of nanowire based infrared p+-i-n+ photodetectors2012Conference paper (Refereed)
    Abstract [en]

    We present a comparative study of electrical and optical properties of two types of p+-i-n+ photodetectors based on self-assembled ensembles of vertical InP nanowires (NWs) monolithically grown on InP. The detectors differ in the type of p+ contact, one detector geometry has p+-i-n+ segments integrated into the NWs (type A) while the other detector has i-n+ NW segments grown directly on a p+ substrate(type B). The samples were prepared by first depositing 80 nm Au nanoparticles on a p+ InP substrate using an aerosol technique and subsequently growing NWs using MOVPE. The NWs have a polytypecrystal structure of alternating wurtzite and zincblende segments. The processing of the detectors include deposition of SiO2, followed by an etching step to remove the oxide from the tip of the NWs, and finally sputtering of ITO on 1x1 mm2 device areas. The two most prominent differences between the detectors concern the current-voltage (I-V) characteristics and the spatial location of generated photocurrent. From spectrally resolved photocurrent measurements, we conclude that the photocurrent in detector type A is primarily generated in the NWs, whereas the photocurrent in type B detectors mainly stems from the substrate. Photogenerated carriers in the substrate diffuse to the NWs where they are effectively funnelled into the NWs. The I-V characteristics of the type A detector displays a non-trivial transport behaviour for forward biases, whereas type B shows excellent rectifying behavior with an ideality factor of about 2.5. We will discuss detailed analysis of the spectral fingerprints of the two detector types revealing the mixed crystal phase of the polytype NWs and bandstructure effects, temperature dependence of the I-V characteristics and typical photodetector parameters.

  • 3.
    Pettersson, Håkan
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Landin, Lars
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Fu, Ying
    Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Kleverman, Mats
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Borgström, Magnus
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Seifert, Werner
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Samuelson, Lars
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Photocurrent spectroscopy on self-assembled InAs quantum dots embedded in InP2005In: Microelectronics Journal, ISSN 0026-2692, Vol. 36, no 3-6, p. 227-230Article in journal (Refereed)
    Abstract [en]

    In this work, we report on an overview of recent results from Fourier transform photocurrent (FTPC) measurements in the infrared spectral region on ensembles of self-assembled InAs quantum dots embedded in a matrix of InP. In interband PC, clear signals related to the dots are observed. Comparing the PC- and PL spectra, we observe that the fundamental transition is absent in the PC spectra, which we interpret in terms of Pauliblocking due to a filled electron ground state of the dots. Our results furthermore suggest that an Auger process is involved in forming the interband PC signal. In intersubband PC, peaks related to transitions from the dots' ground- and first excited states to the conduction band of the matrix are observed. Using a novel approach of combining FTPC with illumination from an additional external non-modulated light source, we have measured the spectral distribution of photoionization of excitons in quantum dots and found an exciton binding energy in good agreement with theoretical calculations.

  • 4.
    Pettersson, Håkan
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Landin, Lars
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Kleverman, Mats
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Seifert, Werner
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Samuelson, Lars
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Fu, Ying
    Phys. Electron. and Photonics, Department of Physics, Gothenburg University, Gothenburg, Sweden.
    Willander, Magnus
    Phys. Electron. and Photonics, Department of Physics, Gothenburg University, Gothenburg, Sweden.
    Intersubband photoconductivity of self-assembled InAs quantum dots embedded in InP2004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 95, no 4, p. 1829-1831Article in journal (Refereed)
    Abstract [en]

    The results from photoconductivity (PC) measurements on InAs dots embedded in InP are presented. The PC technique is recently applied to the study of InAs dots embedded in matrices of GaAs and Al0.3Ga0.7As matrix, respectively. It is demonstrated that this technique reveals important new physical insight into the electronic structure of the InAs/InP dots, information that cannot easily be obtained by other techniques.

  • 5.
    Pettersson, Håkan
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Landin, Lars
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Liu, R. S.
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Seifert, Werner
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Pistol, Mats Erik
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Samuelson, Lars
    Division of Solid State Physics, Lund University, Lund, Sweden.
    Photoexcitation of excitons in self-assembled quantum dots2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, no 21, p. 5046-5048Article in journal (Refereed)
    Abstract [en]

    Using an approach of combining Fourier transform infrared spectroscopy with resonant illumination from a secondary external light source, we have measured the photocurrent (PC) for multiple layers of self-assembled InAs dots embedded in a matrix of InP. Without external illumination, we observe photoexcitation of electrons from bound states in the dots to the InP barrier. By additional illumination from the external light source, a strong broadening of the PC signal is observed. We interpret this broadening in terms of photoexcitation of electrons in the presence of additional holes in the dots created by the external light source. We extract the spectral distribution of the photoexcitation process at 6 and 77 K, respectively, and show by comparison with theoretical calculations that it is consistent with an exciton binding energy of 20 meV.

  • 6.
    Pettersson, Håkan
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Trägårdh, Johanna
    Solid State Physics and the Nanometer Consortium, Lund University, Lund, SUEDE.
    Persson, Ann I.
    Solid State Physics and the Nanometer Consortium, Lund University, Lund, SUEDE.
    Landin, Lars
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Hessman, Dan
    Solid State Physics and the Nanometer Consortium, Lund University, Lund, SUEDE.
    Samuelson, Lars E.
    Solid State Physics and the Nanometer Consortium, Lund University, Lund, SUEDE.
    Infrared Photodetectors in Heterostructure Nanowires2006In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 6, no 2, p. 229-232Article in journal (Refereed)
    Abstract [en]

    We report on spectrally resolved photocurrent measurements on single self-assembled nanowire heterostructures. The wires, typically 3 μm long with an average diameter of 85 nm, consist of InAs with a 1 μm central part of InAsP. Two different sets of wires were prepared with phosphorus contents of 15 ±3% and 35 ±3%, respectively, as determined by energy-dispersive spectroscopy measurements made in transmission electron microscopy. Ohmic contacts are fabricated to the InAs ends of the wire using e-beam lithography. The conduction band offset between the InAs and InAsP regions virtually removes the dark current through the wires at low temperature. In the optical experiments, interband excitation in the phosphorus-rich part of the wires results in a photocurrent with threshold energies of about 0.65 and 0.82 eV, respectively, in qualitative agreement with the expected band gap of the two compositions. Furthermore, a strong polarization dependence is observed with an order of magnitude larger photocurrent for light polarized parallel to the wire than for light polarized perpendicular to the wire. We believe that these wires form promising candidates as nanoscale infrared polarization-sensitive photodetectors.

  • 7.
    Pettersson, Håkan
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Zubritskaya, Irina
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Nghia, Ngo Tuan
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Wallentin, Jesper
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Borgström, Magnus T.
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Storm, Kristian
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Landin, Lars
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Wickert, Peter
    Sol Voltaics AB, Ideon Science Park, Lund, Sweden.
    Capasso, Federico
    School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA.
    Samuelson, Lars
    Solid State Physics and the Nanometer Structure Consortium, Lund University, Lund, Sweden.
    Electrical and optical properties of InP nanowire ensemble p(+)-i-n(+) photodetectors2012In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 13, article id 135201Article in journal (Refereed)
    Abstract [en]

    We report on a comprehensive study of electrical and optical properties of efficient near-infrared p(+)-i-n(+) photodetectors based on large ensembles of self-assembled, vertically aligned i-n(+) InP nanowires monolithically grown on a common p(+) InP substrate without any buffer layer. The nanowires have a polytype modulated crystal structure of wurtzite and zinc blende. The electrical data display excellent rectifying behavior with an ideality factor of about 2.5 at 300 K. The ideality factor scales with 1/T, which possibly reflects deviations from classical transport models due to the mixed crystal phase of the nanowires. The observed dark leakage current is of the order of merely similar to 100 fA/nanowire at 1 V reverse bias. The detectors display a linear increase of the photocurrent with reverse bias up to about 10 pA/nanowire at 5 V. From spectrally resolved measurements, we conclude that the photocurrent is primarily generated by funneling photogenerated carriers from the substrate into the NWs. Contributions from direct excitation of the NWs become increasingly important at low temperatures. The photocurrent decreases with temperature with an activation energy of about 50 meV, which we discuss in terms of a temperature-dependent diffusion length in the substrate and perturbed transport through the mixed-phase nanowires. © 2012 IOP Publishing Ltd.

  • 8.
    Trägårdh, Johanna
    et al.
    Solid State Physics, Lund University, Lund, Sweden.
    Persson, Ann
    Solid State Physics, Lund University, Lund, Sweden.
    Hessman, Dan
    Solid State Physics, Lund University, Lund, Sweden.
    Pettersson, Håkan
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Landin, Lars
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Samuelson, Lars
    Solid State Physics, Lund University, Lund, Sweden.
    Photocurrent Spectroscopy on Single Heterostructure Nanowires2005In: Symposium EE: Progress in Semiconductor Materials V-Novel Materials and Electronic and Optoelectronic Applications, 2005, p. 753-753Conference paper (Refereed)
1 - 8 of 8
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