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@PHDTHESIS{Chen:996548,
      author       = {Chen, Ching-Jung},
      othercontributors = {Jungemann, Christoph and Waser, Rainer},
      title        = {{M}odeling the spatio-temporal evolution of oxygen
                      vacancies in valence change memory cells},
      school       = {Rheinisch-Westfälische Technische Hochschule Aachen},
      type         = {Dissertation},
      address      = {Aachen},
      publisher    = {RWTH Aachen University},
      reportid     = {RWTH-2024-10672},
      pages        = {1 Online-Ressource : Illustrationen},
      year         = {2024},
      note         = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University 2025; Dissertation, Rheinisch-Westfälische
                      Technische Hochschule Aachen, 2024},
      abstract     = {Valence change memory is a promising type of non-volatile
                      memory for next-generation applications. Compared to
                      contemporary NAND Flash, valence change memory cells exhibit
                      advantages such as lower power consumption and faster
                      operating speeds. In addition, devices can be fabricated by
                      existing semiconductor technologies. However, the underlying
                      physical mechanisms intrinsically impose difficulties in
                      manipulating the cell resistance precisely, leading to
                      endurance and data retention issues. It has been observed
                      that the variability of the electrical behavior can be
                      reduced by adopting a large current compliance, which limits
                      the maximum current flowing through the device, but
                      theoretical interpretations are still incomplete.
                      Specifically, most numerical models focus on devices with a
                      large current compliance, while the impact of a small
                      current compliance remains unclear. From a statistical
                      perspective, different tendencies in a wide range of current
                      compliances have been observed in measurements. Different
                      theoretical models have been proposed based on a simple
                      scheme, where one conductive path exists in the oxide layer.
                      However, none of these can explain the observed tendency in
                      a small current compliance regime. In addition, devices with
                      a small current compliance consume less power, thus offering
                      significant advantages for practical applications. The goal
                      of this work is the theoretical investigation of the
                      spatio-temporal evolution of oxygen vacancies resulting in a
                      resistive change of the valence change memory cell. By
                      treating oxygen vacancies as point defects, the same
                      viewpoint as in the density functional theory, findings from
                      ab initio calculations can be applied. This enriches the
                      understanding of local structures and physical quantities
                      during the oxygen migration. To this end, the measurements
                      at a macroscopic level can be explained by the
                      spatio-temporal evolution of oxygen vacancies at a
                      microscopic level. The discussion sheds light on engineering
                      devices for a specialized functionality.},
      cin          = {611410},
      ddc          = {621.3},
      cid          = {$I:(DE-82)611410_20140620$},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.18154/RWTH-2024-10672},
      url          = {https://publications.rwth-aachen.de/record/996548},
}