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@INPROCEEDINGS{Schnedler:1044267,
      author       = {Schnedler, Michael and Lan, Qianqian and Freter, Lars and
                      Butté, Raphaël and Grandjean, Nicolas and Carlin,
                      Jean-François and Eisele, Holger and Portz, Verena and Sun,
                      Qian and Ji, Keyan and Lymperakis, Liverios and Ebert,
                      Philipp and Dunin-Borkowski, Rafal},
      title        = {{F}ermi level pinning at nitride semiconductor surfaces and
                      interfaces},
      reportid     = {FZJ-2025-03137},
      year         = {2025},
      abstract     = {Fermi level pinning plays a crucial role in nitride
                      semiconductor growth, contact formation, and the engineering
                      of insulating layers. While pinning effects and carrier
                      accumulation have been widely studied at nitride surfaces,
                      their impact on interfaces remains equally significant. In
                      this presentation, we explore Fermi level pinning at
                      non-polar (10-10) surfaces and interfaces using scanning
                      tunneling spectroscopy, off-axis electron holography (EH) in
                      TEM, and complementary DFT calculations.First we discuss the
                      interplay of intrinsic surface states, defects, and air
                      exposure on the Fermi level pinning at non-polar GaN, AlInN,
                      AlGaN, and InN surfaces as well as the origin of electron
                      accumulation. The empty group III-derived dangling bond is
                      found to govern Fermi level pinning on most n-type group III
                      nitrides, but not for InN, where defects dominate. Likewise
                      for p-type doping defects govern the Fermi level pinning,
                      too. Air exposure is found to shift pinning levels toward
                      the band edges, attributed to water adsorption and
                      dissociation, passivating intrinsic and extrinsic gap
                      states. The results demonstrate that for all group III
                      nitride semiconductors, including InN electron accumulation
                      is not intrinsic, but rather extrinsically induced by
                      adlayers. Furthermore, we demonstrate the quantification of
                      Fermi level pinning by EH in TEM using the example of
                      focussed ion beam (FIB) implanted carbon. FIB preparation
                      induces a Fermi level pinning about 0.7 eV above the valence
                      band edge, attributed to C on N sites. Annealing experiments
                      allow to probe the defect dynamics and barriers. Notably, it
                      is demonstrated that carbon undergoes an atomic
                      site-switching process, transitioning from a substitutional
                      to an interstitial site where it becomes electrically
                      inactive upon annealing. These findings provide a profound
                      foundation for understanding the stability of insulating
                      layers in ternary nitrides and offer critical insights for
                      optimizing nitride-based electronic and insulating
                      structures.},
      month         = {Jul},
      date          = {2025-07-06},
      organization  = {15th International Conference on
                       Nitride Semiconductors, Malmö
                       (Sweden), 6 Jul 2025 - 11 Jul 2025},
      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)6},
      url          = {https://juser.fz-juelich.de/record/1044267},
}