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@INPROCEEDINGS{Schnedler:1044269,
      author       = {Schnedler, Michael},
      title        = {{L}ight-excited scanning tunneling spectroscopy of
                      {III}-{V} semiconductors},
      reportid     = {FZJ-2025-03139},
      year         = {2024},
      abstract     = {The efficiency of solar cell and optoelectronic devices is
                      closely connected to the nanoscale distribution of charge
                      carriers. For example, defects can give rise to
                      non-radiative carrier recombination centers, reducing the
                      charge-carrier concentration locally. Such effects are
                      detrimental to both the electron-light and light-electron
                      conversion efficiencies in optoelectronic and solar cell
                      devices, respectively. In order to understand the physical
                      processes involved at the atomic scale, the materials used
                      in the device structures need to be investigated
                      simultaneously under illumination and with atomic
                      resolution.Photoexcited scanning tunneling spectroscopy
                      (STS) is ideally suited to probe the illumination-induced
                      local surface photovoltage, band bending, carrier
                      concentrations, and the electrostatic potential
                      distribution. A quantitative understanding of photoexcited
                      tunneling spectroscopy is unfortunately not at all straight
                      forward. This is further aggravated by the fact that only
                      for very few materials tunneling spectra can be intuitively
                      understood, while for all other materials simulations of the
                      tunnel current are a prerequisite for extracting the
                      underlying physics, even without illumination. Therefore, we
                      developed a theoretical modelling of photoexcited tunneling
                      spectroscopy using simulations of the exact sample structure
                      as “digital twin”. In this presentation, we will
                      illustrate the methodology and apply it to III-V
                      semiconductors to extract the local non-equilibrium
                      charge-carrier concentration and redistribution. The same
                      methodology is also applied to analyze tunneling spectra
                      without photoexcitation and off-axis electron holography
                      measurements in a transmission electron microscope to derive
                      potential maps, electron affinity differences, mean inner
                      potentials, polarization, band offsets, etc.},
      organization  = {Universität Münster - Seminar
                       "Aktuelle Fragen der Nanophysik",
                       Münster (Germany)},
      subtyp        = {Invited},
      cin          = {ER-C-1},
      cid          = {I:(DE-Juel1)ER-C-1-20170209},
      pnm          = {5351 - Platform for Correlative, In Situ and Operando
                      Characterization (POF4-535)},
      pid          = {G:(DE-HGF)POF4-5351},
      typ          = {PUB:(DE-HGF)31},
      url          = {https://juser.fz-juelich.de/record/1044269},
}