Search Results - (Author, Cooperation:M. Kunst)

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  1. 1
    Staff View
    Publication Date:
    2015-03-04
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Keywords:
    Cultural Evolution/*history ; Europe/ethnology ; Genome, Human/genetics ; *Grassland ; History, Ancient ; Human Migration/*history ; Humans ; Language/*history ; Male ; Polymorphism, Genetic/genetics ; Population Dynamics ; Russia
    Published by:
    http://www.nature.com/

    Latest Papers from Table of Contents or Articles in Press
  2. 2
    Neitzert, H. C. ; Hirsch, W. ; Kunst, M.

    [S.l.] : American Institute of Physics (AIP)
    Published 1993
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    During removal of amorphous silicon films deposited on crystalline silicon substrates by dry etching in a hydrogen plasma the kinetics of mobile excess charge carriers have been followed by measuring the change of the microwave reflection after laser pulse illumination. Following the amplitude of the measured transient signals the thickness of the remaining amorphous silicon film can be determined and the decay in the nanosecond time range yields information about the defect density of the substrate surface. The impact of the plasma process on the surface recombination is shown and a criterion for endpoint detection is given in the case of a-Si:H removal from crystalline silicon covered with a SiO2 layer.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.353988

    Articles: DFG German National Licenses
  3. 3
    Kunst, M. ; Neitzert, H.-C.

    [S.l.] : American Institute of Physics (AIP)
    Published 1991
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    The relaxation of pulse-induced mobile charge carriers in a-Si:H films is followed by transient photoconductivity measurements in the microwave frequency range (time resolved microwave conductivity measurements). It is shown that a-Si:H films deposited at substrate temperatures lower than 150 °C are characterized by a lower electron drift mobility and a higher deep trap concentration for electrons than a-Si:H films deposited at 250 °C, where films deposited at 150 °C have only a lower drift mobility. Annealing of a film deposited at 30 °C leads to a higher drift mobility and a lower deep trap concentration with increasing annealing temperature. However, the (opto)electronic properties of the annealed films are still inferior to those of films deposited at the annealing temperature.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.347444

    Articles: DFG German National Licenses
  4. 4
    Swiatkowski, C. ; Sanders, A. ; Buhre, K.-D. ; Kunst, M.

    [S.l.] : American Institute of Physics (AIP)
    Published 1995
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    Theory and measurements of the conductivity and the (transient) photoconductivity in the microwave frequency range are presented. The theory is tested on noninvasive measurements of semiconductors with known properties, i.e., Si wafers, in a simple apparatus. Quantitative agreement between theory and experiment is found without the use of adjustable parameters. A contactless and accurate determination of the conductivity of Si wafers in a restricted conductivity range is proposed. The quantitative evaluation of photoconductivity measurements makes a detailed discussion of nonuniform photoconductivity possible. The requirements for reliable measurements of nonhomogeneous charge carrier kinetics are discussed. © 1995 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.360206

    Articles: DFG German National Licenses
  5. 5
    Grunow, P. ; Kunst, M.

    [S.l.] : American Institute of Physics (AIP)
    Published 1995
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    The use of the photothermal deflection (PD) technique for the characterization of semiconductors is investigated by measurements on crystalline silicon and CdS. The influence of the absorption profile and recombination at the back side is involved in the theoretical description and compared with experimental results. It is shown that reliable values for the electronic transport parameters can be determined. PD signals are relatively specific and enable one to assess the suitability of electronic transport models. The presence of nonlinear surface recombination due to space-charge fields can be deduced from the measurements of the deflection signal. Also, the inadequacy of linear volume recombination as a description for excess carrier decay in CdS is clearly observed. © 1995 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.358746

    Articles: DFG German National Licenses
  6. 6
    Neitzert, H. C. ; Layadi, N. ; Roca i Cabarrocas, P. ; Vanderhaghen, R. ; Kunst, M.

    [S.l.] : American Institute of Physics (AIP)
    Published 1995
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    The damage induced by hydrogen and helium plasmas at the surface of crystalline silicon has been monitored in situ by time-resolved microwave conductivity and by spectroscopic ellipsometry measurements. Both plasma treatments increase the decay rate of the optically generated excess charge carriers and decrease the amplitude of the microwave reflection transients. While for the helium plasma a high density of electronic defects is created immediately after plasma ignition, a continuously increasing number of recombination centers is observed in the case of the hydrogen plasma exposure. In support of the transient microwave measurements, the analysis of the spectroscopic ellipsometry measurements reveals the creation of a damaged surface layer, which in the case of the helium plasma exposure has a high and in the case of the hydrogen plasma a low fraction of amorphous silicon. This can be explained by the different nature of the processes involved in the interaction of hydrogen (chemical) and helium (physical) plasmas with the silicon surface. After a constant plasma exposure time the damaged surface layer is thicker in the case of the hydrogen plasma exposure. Moreover, the helium plasma treatment produces a more defective overlayer as deduced from the faster decay of the transient microwave signals. © 1995 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.360302

    Articles: DFG German National Licenses
  7. 7
    Elmiger, J. R. ; Kunst, M.

    Woodbury, NY : American Institute of Physics (AIP)
    Published 1996
    Staff View
    ISSN:
    1077-3118
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    Contactless measurements of the conductance of silicon wafers with silicon nitride top layers are presented. The deposition of silicon nitride layers leads to an increase of the conductance, both for p-Si and n-Si. This is attributed to the increase of the number of electrons in the Si wafer, in an inversion layer in p-Si, and in an accumulation layer in n-Si. Comparison of the increase of the conductance with the fixed charge density in the nitride layer points to a strongly reduced electron mobility in these layers. It is shown that the change of the conductance increases with growing thickness of the nitride layer up to a thickness of 20 nm, whereafter a constant value is attained. © 1996 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.117772

    Articles: DFG German National Licenses
  8. 8
    Werner, A. ; Kunst, M. ; Moustakas, T. D.

    Woodbury, NY : American Institute of Physics (AIP)
    Published 1990
    Staff View
    ISSN:
    1077-3118
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    The influence of the silicon concentration on excess charge carrier kinetics in molecular beam epitaxy grown GaAs films has been studied by transient photoconductivity measurements with a contactless microwave conductivity technique. Several decay channels can be distinguished: an initial, fast second-order decay more active in low impurity films and at high excitation intensities, and a slower decay component characterized by effective decay times ranging from 6 μs for low impurity samples and increasing decay times with increasing Si concentration. The initial, fast second-order decay is attributed to electron-hole recombination and is quenched by hole traps present at higher Si concentrations. In low impurity samples, the slower decay channel is ascribed to a deep electron trapping channel which can be saturated at higher excitation intensities. In high impurity samples, the decay time exceeds 100 μs and may be due to electron-trapped hole transitions.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.103152

    Articles: DFG German National Licenses
  9. 9
    Kunst, M. ; Werner, A.

    [S.l.] : American Institute of Physics (AIP)
    Published 1985
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    It is shown that photoconductivity transients in a-Si:H measured in a coplanar electrode configuration and by microwave reflection are identical. This proves that transients obtained with these techniques reflect free charge carrier kinetics where the influence of contacts can be neglected. Evidence is given that charge carrier transport is different in the surface layer and in the bulk. The influence of the temperature and the exciting light intensity on transient photoconductivity data are explained by a tentative recombination model which takes dispersive transport of holes and electrons into account.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.335940

    Articles: DFG German National Licenses
  10. 10
    Kunst, M. ; Beck, G.

    [S.l.] : American Institute of Physics (AIP)
    Published 1986
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    The study of the excess conductivity induced in a material by pulsed optical excitation yields information on the optoelectronic properties of the material and is receiving increasing attention. As conventional conductivity techniques are hampered by the need to apply electrical contacts, we have investigated the reliability and the possibilities of microwave conductivity measurements. This paper first presents the general background for excess conductivity measurements in the microwave range, and then derives the quantitative relationship between the reflected microwave signal and the change in conductivity for a wafer of single-crystalline Si. For this sample, the theory of excess charge carrier kinetics is also developed. After a short description of our apparatus, kinetic measurements on a nano- and microsecond timescale are compared to theory.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.337612

    Articles: DFG German National Licenses
  11. 11
    Werner, A. ; Kunst, M.

    [S.l.] : American Institute of Physics (AIP)
    Published 1988
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    Charge carrier dynamics in doped and undoped hydrogenated amorphous silicon (a-Si:H) films is studied by contactless time-resolved photoconductivity measurements. Subband-gap and above band-gap excitation are used to generate excess mobile charge carriers. In undoped a-Si:H the electron decay at charge carrier concentrations larger than 1016 cm−3 is mainly due to an electron-hole recombination which is controlled by hole dispersion. n doping introduces hole traps which increase the effective electron lifetime drastically as they quench this electron-hole recombination channel. At high n-doping levels the electron decay becomes faster due to an increase of the concentration of recombination centers upon doping. In lightly doped p-type samples the transient photoconductivity reflects the interaction of mobile holes with states in the valence-band tail. In heavily doped p- and n-type films the majority carriers decay by a second-order recombination process with trapped minority charge carriers. The transport parameters deduced agree with time-of-flight data.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.341465

    Articles: DFG German National Licenses
  12. 12
    Kunst, M. ; Beck, G.

    [S.l.] : American Institute of Physics (AIP)
    Published 1988
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    In previous work [J. Appl. Phys. 60, 3558 (1986)] an introduction was given to the study of charge carrier kinetics in semiconductors by microwave conductivity measurements. This paper compares quantitatively our experimental results to theoretical calculations for single-crystalline Si wafers, taking into account the dependence on the microwave frequency and the dark conductivity of the sample, which ranged from σ=0.2 to 400 Ω−1 m−1. In particular, difficulties arising from experimental conditions that cannot easily be treated by theory are discussed. It is shown that quantitative measurements of samples with low dark conductivity can be performed even in a very simple configuration, which permits determination of the sum of charge carrier mobilities.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.340013

    Articles: DFG German National Licenses
  13. 13
    Beck, G. ; Kunst, M.

    [S.l.] : American Institute of Physics (AIP)
    Published 1986
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    Conventional laser scanning techniques for the topological characterization of photoactive materials and devices are hampered by the need to apply electrical contacts. We present a technique to overcome this limitation using the relative change of reflected microwave power to probe the conductivity locally induced in the sample. After a discussion of the theoretical background and the limitations of the method the apparatus is described. Application to scan the surface of a semiconductor chip carrying an electrode structure is used to discuss the resolution and linearity.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.1138968

    Articles: DFG German National Licenses
  14. 14
    Kunst, M. ; Sies, H. ; Akerboom, T.P.M.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0005-2736
    Keywords:
    (Rat liver) ; ATP stimulation ; Membrane vesicle ; S-(2,4-Dinitrophenyl)glutathione uptake ; Transport
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1016/0005-2736(89)90389-1

    Articles: DFG German National Licenses
  15. 15
    Kunst, M. ; Sies, H. ; Akerboom, T.P.M.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0005-2736
    Keywords:
    (Rat liver) ; Glutathione S-transferase ; Membrane vesicle ; Photoaffinity labeling ; S-(4-Azidophenacyl)glutathione ; Transport
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1016/0005-2736(89)90168-5

    Articles: DFG German National Licenses
  16. 16
    Janson, J.P.M. ; Kunst, M. ; Rip, A. ; Bordewijk, P.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0009-3084
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Biology
    Chemistry and Pharmacology
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://linkinghub.elsevier.com/retrieve/pii/0009-3084(72)90010-2

    Articles: DFG German National Licenses
  17. 17
    Janson, J.P.M. ; Kunst, M. ; Rip, A. ; Bordewijk, P.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0009-3084
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Biology
    Chemistry and Pharmacology
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://linkinghub.elsevier.com/retrieve/pii/0009-3084(73)90045-5

    Articles: DFG German National Licenses
  18. 18
    Albert, K. ; Kunst, M. ; Bayer, E. ; Spraul, M. ; Bermel, W.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0021-9673
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Chemistry and Pharmacology
    Type of Medium:
    Electronic Resource
    URL:
    http://linkinghub.elsevier.com/retrieve/pii/S0021-9673(01)84489-7

    Articles: DFG German National Licenses
  19. 19
    Werner, A. ; Kunst, M. ; Beck, G. ; Lilie, J. ; Tributsch, H.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0038-1098
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://linkinghub.elsevier.com/retrieve/pii/0038-1098(85)90549-6

    Articles: DFG German National Licenses
  20. 20
    Kunst, M. ; Werner, A.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0038-1098
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://linkinghub.elsevier.com/retrieve/pii/0038-1098(85)91048-8

    Articles: DFG German National Licenses