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@PHDTHESIS{Xu:828408,
      author       = {Xu, Chencheng},
      title        = {{I}n situ studies of the growth and oxidation of complex
                      metal oxides by pulsed laser deposition},
      volume       = {140},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2017-02369},
      isbn         = {978-3-95806-204-7},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {IV, 159 S.},
      year         = {2017},
      note         = {RWTH Aachen, Diss., 2016},
      abstract     = {Pulsed Laser Deposition (PLD) is a versatile deposition
                      technique for complex metal oxide thin films and
                      heterostructures. Without sophisticated parameter
                      engineering, a stoichiometric transfer between target and
                      substrate can take place in a large pressure range of
                      different gas ambient. As a result, PLD is widely applied in
                      many research laboratories. However, the basic processes
                      during PLD growth are not well understood. Therefore most of
                      the research groups only carry out parameter optimization
                      for PLD empirically. Although the thin film properties can
                      be enhanced by empirical optimization of growth parameters,
                      the exact correlation between PLD growth process and thin
                      film property is hardly known. A better understanding in the
                      correlation between PLD growth and thin film properties is
                      gaining arising attention with its increasing importance for
                      different complex metal oxide based electronics nowadays.
                      The aspects to be investigated are different in various
                      material systems. The first example is the Resistive Random
                      Access Memories (ReRAM) based on complex metal oxides, e.g.
                      SrTiO$_{3}$ (STO) thin films, where the defects like cation
                      vacancies in thin oxide films play a crucial role for the
                      switching behavior. Only by understanding the defect
                      formation process during the PLD process a rational design
                      of defects in the thin film could be possible. The
                      $\textit{in-situ}$ studies on the defect formation process
                      during STO thin film growth are thus necessary. The second
                      example is the conductive interface between two band
                      insulators, e.g. LaAlO$_{3}$ (LAO) and STO. Since its
                      discovery one decade ago, the formation process of the
                      conductive interface is not well understood. To understand
                      the physical mechanism behind the conductive interface
                      formation, it is of pivotal importance to learn when the
                      formation takes place. Furthermore, the conductivity of
                      LAO/STO heterostructures are significantly influenced by the
                      defects like oxygen vacancies, which can be
                      incorporated/eliminated both by growth and post-annealing
                      process. So the $\textit{in-situ}$ study on the conductive
                      interface formation and the study on the oxygen vacancy
                      incorporation/elimination process during the growth and
                      annealing process are needed. In this work the
                      $\textit{in-situ}$ study on the defect formation process
                      during STO homoepitaxy is carried out. The cation
                      non-stoichiometries in STO thin films are introduced by the
                      preferential scattering process during laser plume
                      propagation. STO thin films with cation non-stoichiometry
                      remains at the early growth stage within 2D growth mode. The
                      defects are in this growth stage point defects inhibiting
                      surface diffusion through surface strain. The cation
                      non-stoichiometry leads further to the formation of extended
                      defects as growth proceeds and the growth mode is changed.
                      As an example, the Sr rich STO exhibits firstly 2D growth
                      with subsequent surface termination change from TiO$_{2}$ to
                      SrO at low film thickness, whereas the further growth
                      establishes anti-phase boundaries and lead to 3D island
                      growth. The conductive interface formation process between
                      LAO and STO is studied $\textit{in-situ}$ and
                      $\textit{real-time}$ with Oblique Incidence Reflectance
                      Difference technique (OIRD). In addition, the incorporation
                      and elimination processes of oxygen vacancies in LAO/STO
                      heterostructures are investigated as well. It is observed
                      from the growth process that the first 3 unit cells (u.c.)
                      LAO differ from the rest of LAO unit cells, indicating the
                      electronic transfer happens at 3 u.c. and does not influence
                      the first 3 u.c. LAO. The incorporation of oxygen vacancies
                      into the STO takes place during the PLD growth of LAO, while
                      the elimination of oxygen vacancies in STO is optimal at the
                      growth temperature and pressure. The main reason for the
                      incorporation of oxygen vacancies in STO is the impinging
                      particles with high kinetic energy.},
      cin          = {PGI-7},
      cid          = {I:(DE-Juel1)PGI-7-20110106},
      pnm          = {899 - ohne Topic (POF3-899)},
      pid          = {G:(DE-HGF)POF3-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2017080808},
      url          = {https://juser.fz-juelich.de/record/828408},
}