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@INPROCEEDINGS{Gunel:133834,
      author       = {Gunel, Yusuf and Batov, Igor and Hardtdegen, Hilde and
                      Sladek, Kamil and Winden, Andreas and Weis, Karl and
                      Panaitov, Gregory and Grützmacher, Detlev and Schäpers,
                      Thomas},
      title        = {{S}upercurrent and {M}agnetoresistance {O}scillations
                      in{N}b/{I}n{A}s-{N}anowire/{N}b {J}osephson junctions},
      reportid     = {FZJ-2013-02225},
      year         = {2012},
      abstract     = {One of the common goals in semiconductor/superconductor
                      hybrid de-vices is to fabricate Schottky barrier free
                      contacts at the interface of the two materials.[1] The
                      natural formation of an electron accumu-lation layer on InAs
                      surfaces prohibits the formation of a Schottky barrier.
                      Therefore this material became the most preferred one for
                      semiconducting weak links in Josephson junctions. This
                      unique prop-erty of InAs in combination with the bottom-up
                      growth approach of nanowires, led to many interesting
                      experiments, e.g. tunable super-currents or Cooper pair beam
                      splitters.[3] In these experiments aluminum (Al) was used as
                      a superconducting material, which has a low critical
                      temperature (Tc) and a low critical magnetic eld (Bc). As an
                      alternative, we have used superconduct-ing Niobium (Nb) with
                      a high Tc and Bc that oers the advantage to study Josephson
                      properties in dierent regimes. In this report, we have used
                      InAs nanowires with two dierent bulk carrier
                      concentra-tions, i.e. 10 18 cm 3 (low doped) and 10 19 cm 3
                      (highly doped). The contacting process of Nb electrodes has
                      been realized by standard electron beam lithography. We
                      systematically investigated the basic Josephson properties,
                      i.e. the eect of temperature, magnetic eld and electric eld
                      on the super-current through InAs nanowires. By taking
                      advantage of the high Tc ( 9:3K) of the superconducting Nb,
                      we were able to measure a super-current up to 4.0K. The
                      highest critical current Ic 100nA has been measured at 0.4K
                      for a junctions with a highly doped InAs nanowire. For low
                      doped nanowire Josephson junctions, a full control of the
                      su-percurrent has been achieved by applying a gate bias. We
                      have found a monotonous dependence of the measured critical
                      current in the pres-ence of a perpendicular magnetic eld
                      rather than a Fraunhofer-like diraction pattern. The
                      experimental results have been compared to a recent
                      theoretical model of Ref.[4] In addition, we studied the
                      supercur-rent and conductance uctuations as a function of
                      gate voltage. Here, a remarkable enhancement of the
                      conductance uctuation amplitude has been observed. In the
                      last part, we have studied the magnetore-sistance
                      oscillations in the voltage state of Josephson junctions.
                      [1] Th. Schapers, Superconductor/Semiconductor Junctions,
                      174 (Springer Tracts on Modern Physics, 2001) [2] Y.-J. Doh,
                      J. A. van Dam, A. L. Roest, E. P. A. M. Bakkers, L. P.
                      Kouwenhoven, and S. D. Franceschi, Science 309, 272 (2005)
                      [3] L. Hofstetter, S. Csonka, J. Nygard, and C.
                      Schonenberger, Na-ture 461, 960 (2009) [4] J. C. Cuevas and
                      F. S. Bergeret, Phys. Rev. Lett. 99, 217002 (2007)},
      month         = {Jul},
      date          = {2012-07-27},
      organization  = {International Conference on the
                       Physics of Semiconductors 2012, Zürich
                       (CH), 27 Jul 2012 - 3 Aug 2012},
      subtyp        = {After Call},
      cin          = {PGI-9 / PGI-8},
      cid          = {I:(DE-Juel1)PGI-9-20110106 / I:(DE-Juel1)PGI-8-20110106},
      pnm          = {422 - Spin-based and quantum information (POF2-422)},
      pid          = {G:(DE-HGF)POF2-422},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/133834},
}