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@PHDTHESIS{Felter:866243,
      author       = {Felter, Janina},
      title        = {{D}ifferent growth modes of molecular adsorbate systems and
                      2{D} materials investigated by low-energy electron
                      microscopy},
      volume       = {206},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2019-05409},
      isbn         = {978-3-95806-434-8},
      series       = {Schriften des Forschungszentrums Jülich Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {vi, 114, XXXIV},
      year         = {2019},
      note         = {Dissertation, RWTH Aachen University, 2018},
      abstract     = {In this thesis, the growth of two organic molecules, PTCDA
                      and NTCDA, and of the 2D material hBN on copper surfaces are
                      investigated. The particular focus of this work lies on the
                      interplay of different interaction mechanisms occurring for
                      these systems which lead to completely different growth
                      modes including dendrite-like, fractal growth modes and
                      compact island formation. $\textbf{Organic Molecules}$ In
                      the first part of this thesis, the growth of PTCDA and NTCDA
                      on the Cu(001) surface are investigated. Although these two
                      molecules are chemically closely related, they exhibit two
                      different growth modes on this metal surface. For PTCDA on
                      Cu(001), it is well known that the attractive intermolecular
                      interaction of the PTCDA molecules, caused by the quadrupole
                      moment of the molecule, leads to the growth of compact
                      islands at already very low coverage [54, 66]. This process
                      is quantified in this work by determining three important
                      growth parameters which influence the island formation: the
                      critical cluster size, the cohesion energy of two PTCDA
                      molecules and the diffusion barrier of the adsorbed
                      molecules. By analyzing island size distributions within the
                      aggregation regime and applying methods developed for atomic
                      nucleation on surfaces, it was possible to determine the
                      critical cluster size i for temperatures between 300K and
                      390K. This parameter corresponds to the number of molecules
                      in the largest cluster of molecules which is not yet stable.
                      The fact that for temperatures below 317K two molecules are
                      already forming a stable cluster (i = 1) enabled to
                      calculate the diffusion barrier for individual molecules on
                      this surface: E$_{D}$ = (0.45 ± 0.21) eV. With increasing
                      temperature, one expects an increase of the critical cluster
                      size. However, the case of i = 2 is experimentally not
                      observed; instead at temperatures above 317K, four molecules
                      are needed to form a stable cluster (i = 3). This direct
                      change in critical cluster size from 1 to 3 is explained by
                      the specific geometric conditions for the case of
                      PTCDA/Cu(001). Furthermore, using pair-potential
                      calculations it is possible to determine a second crucial
                      energy for layer growth: the cohesion energy of two
                      molecules which amounts to E$^{(2)}_{B}$ = (0.89 ± 0.34)
                      eV. In contrast to PTCDA, NTCDA exhibits a completely
                      different growth mode on the same substrate in the
                      submonolayer regime for temperatures at and above room
                      temperature. Clear indications are found for a
                      dendrite-like, fractal growth mode. This finding is based on
                      BF-LEEM measurements indicating that no compact [...]},
      cin          = {PGI-3},
      cid          = {I:(DE-Juel1)PGI-3-20110106},
      pnm          = {899 - ohne Topic (POF3-899)},
      pid          = {G:(DE-HGF)POF3-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/866243},
}