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@ARTICLE{Chen:916658,
      author       = {Chen, Genyu and Chakraborty, Debamitra and Cheng, Jing and
                      Mikulics, Martin and Komissarov, Ivan and Adam, Roman and
                      Bürgler, Daniel E. and Schneider, Claus M. and Hardtdegen,
                      Hilde and Sobolewski, Roman},
      title        = {{T}ransient {TH}z {E}mission and {E}ffective {M}ass
                      {D}etermination in {H}ighly {R}esistive {G}a{A}s {C}rystals
                      {E}xcited by {F}emtosecond {O}ptical {P}ulses},
      journal      = {Crystals},
      volume       = {12},
      number       = {11},
      issn         = {2073-4352},
      address      = {Basel},
      publisher    = {MDPI},
      reportid     = {FZJ-2023-00010},
      pages        = {1635 -},
      year         = {2022},
      abstract     = {We present comprehensive studies on the emission of
                      broadband, free-space THz transients from several highly
                      resistive GaAs samples excited by femtosecond optical
                      pulses. Our test samples are characterized by different
                      degrees of disorder, ranging from nitrogen-implanted to
                      semi-insulating and annealed semi-insulating GaAs crystals.
                      In our samples, we clearly observed transient THz emissions
                      due to the optical rectification effect, as well as due to
                      the presence of the surface depletion electrical field.
                      Next, we arranged our experimental setup in such way that we
                      could observe directly how the amplitude of surface-emitted
                      THz optical pulses is affected by an applied, in-plane
                      magnetic field. We ascribe this effect to the Lorentz force
                      that additionally accelerates optically excited carriers.
                      The magnetic-field factor η is a linear function of the
                      applied magnetic field and is the largest for an annealed
                      GaAs sample, while it is the lowest for an N-implanted GaAs
                      annealed at the lowest (300 °C) temperature. The latter is
                      directly related to the longest and shortest trapping times,
                      respectively, measured using a femtosecond optical
                      pump-probe spectroscopy technique. The linear dependence of
                      the factor η on the trapping time enabled us to establish
                      that, for all samples, regardless of their crystalline
                      structure, the electron effective mass was equal to 0.059 of
                      the electron mass m0, i.e., it was only about $6\%$ smaller
                      than the generally accepted 0.063m0 value for GaAs with a
                      perfect crystalline structure.},
      cin          = {PGI-6 / ER-C-2},
      ddc          = {540},
      cid          = {I:(DE-Juel1)PGI-6-20110106 / I:(DE-Juel1)ER-C-2-20170209},
      pnm          = {5213 - Quantum Nanoscience (POF4-521)},
      pid          = {G:(DE-HGF)POF4-5213},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000894870600001},
      doi          = {10.3390/cryst12111635},
      url          = {https://juser.fz-juelich.de/record/916658},
}