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@ARTICLE{Sommer:1007138,
      author       = {Sommer, Nils and Dittmann, Regina and Menzel, Stephan},
      title        = {{E}ffect of {O}xygen {E}xchange between {T}wo {O}xide
                      {L}ayers of a {M}emristive {B}ilayer {V}alence-{C}hange
                      {M}emory {C}ell on the {S}witching {P}olarity},
      journal      = {Physical review applied},
      volume       = {19},
      number       = {4},
      issn         = {2331-7019},
      address      = {College Park, Md. [u.a.]},
      publisher    = {American Physical Society},
      reportid     = {FZJ-2023-01962},
      pages        = {044084},
      year         = {2023},
      abstract     = {Valence-change memory (VCM) cells are promising candidates
                      for future nonvolatile memory devices. A special setup of
                      VCM devices consists of bilayer cells where two thin oxide
                      layers are placed in between two metal electrodes. One oxide
                      layer serves as a tunnel barrier, whereas the second oxide
                      layer is a highly doped conductive semiconductor.
                      Experiments show that an exchange of oxygen between the two
                      layers changes the resistance of the cell. However, the
                      exchange process and how it influences the resistance is not
                      well understood yet. With a drift-diffusion model for
                      electrons and oxygen vacancies, we investigate the movement
                      and exchange of oxygen vacancies and their influence on the
                      band structure as well as on the shape of the tunnel
                      barrier. The simulation results show that a high
                      oxygen-vacancy concentration lowers the height of the tunnel
                      barrier; thus it increases the conductivity of the bilayer
                      cell. The effect of the band lowering is stronger in
                      materials with low permittivity. Hence, two different
                      resistance states evolve if there is an exchange of oxygen
                      between the two oxide layers with different permittivities.
                      Thereby, the switching polarity depends on the relation of
                      the permittivities of the two oxide layers. Furthermore, it
                      is revealed that resistance switching can be induced by the
                      movement of vacancies only inside the conductive oxide,
                      without any oxygen exchange between the layers.},
      cin          = {PGI-7 / JARA-FIT},
      ddc          = {530},
      cid          = {I:(DE-Juel1)PGI-7-20110106 / $I:(DE-82)080009_20140620$},
      pnm          = {5233 - Memristive Materials and Devices (POF4-523) / BMBF
                      16ME0399 - Verbundprojekt: Neuro-inspirierte Technologien
                      der künstlichen Intelligenz für die Elektronik der Zukunft
                      - NEUROTEC II - (BMBF-16ME0399) / BMBF 16ME0398K -
                      Verbundprojekt: Neuro-inspirierte Technologien der
                      künstlichen Intelligenz für die Elektronik der Zukunft -
                      NEUROTEC II - (BMBF-16ME0398K)},
      pid          = {G:(DE-HGF)POF4-5233 / G:(DE-82)BMBF-16ME0399 /
                      G:(DE-82)BMBF-16ME0398K},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000981965200002},
      doi          = {10.1103/PhysRevApplied.19.044084},
      url          = {https://juser.fz-juelich.de/record/1007138},
}