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@PHDTHESIS{Babajani:200870,
      author       = {Babajani, Ninet},
      title        = {{L}adungstransportuntersuchungen an nanofunktionalen
                      {B}auelementen mit {D}iodencharakteristik basierend auf
                      funktionalisierten {N}anopartikeln},
      volume       = {42},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2015-03241},
      isbn         = {978-3-95806-026-5},
      series       = {Schriften des Forschungszentrums Jülich. Reihe Information
                      / information},
      pages        = {iv, 138, XLVII S.},
      year         = {2015},
      note         = {RWTH Aachen, Diss., 2014},
      abstract     = {The success of silicon-based information technology is
                      mainly based on its cost effectiveness and on its efficient
                      information storage in semiconductor memory cells. The
                      miniaturization of electronic components is a key element in
                      semiconductor technology that drives operating speed and
                      energy efficiency. However, further shrinking of device
                      structures will face huge technological challenges, so that
                      alternative technologies have to be considered. So called
                      hybrid concepts combine the existing silicon-based
                      electronics with new technologies such as molecular
                      electronics in which molecules or functionalized
                      nanoparticles are studied as electronic components. In this
                      work, different
                      electrode-molecule/nanoparticle/molecule-electrode devices
                      were investigated for their suitability as a diode device in
                      a CMOS compatible system. These arrangements were
                      systematically varied and the transport properties of
                      different mono- or bifunctionalized gold nanoparticles
                      (AuNPs) were characterized between homo- or heterometallic
                      nanoelectrodes (HoNE or HeNe). Mixed functionalized AuNPs
                      and Janus AuNPs (d = 14 $\pm$ 1 nm), with different
                      molecules on opposite hemispheres, were used as
                      bifunctionalized AuNP. The first step for understanding the
                      electron transport through these
                      electrode-molecule/AuNP/molecule-electrode devices was the
                      optimization and characterization of the individual
                      components of the devices. Investigations of the AuNPs and
                      AuNP adsorption on the different metals showed that the
                      binding of single-Janus-AuNPs can be controlled by the pH
                      buffer solution. Furthermore, surface-sensitive methods
                      (XPS) confirmed the functionality of the molecules after the
                      immobilization and drying and demonstrated the directed
                      orientation of the Janus-AuNPs. Optimizations in the process
                      of fabrication of HeNE, which involves electron-beam
                      lithography in combination with a hard mask, allowed to
                      produce HeNE, with a distance of d = 13 $\pm$ 2 nm, and a
                      yield of about 50\%. The AuNPs were immobilized between the
                      nano-electrodes by dielectrophoretic trapping. The
                      electrical characterization of the devices included the
                      analysis of the transport mechanisms, such as Arrhenius,
                      superexchange or tunneling transport. The tunnelling
                      transport was additionally analyzed by the Simmonsmodel,
                      Landauer formula and by „Transition Voltage
                      Spectroscopy“. The charge transport studies of mixed
                      functionalized AuNPs between the HeNe showed diode
                      characteristic due to the different HOMO/LUMO energies of
                      the twomolecules. However, mixed AuNPs showed an
                      uncontrolled orientation between the nanoelectrodes and
                      thus, random asymmetrical contacts are expected.
                      Alsomonofunctionalized AuNP were immobilized in order to
                      obtain diode characteristics. In this case the resulting
                      asymmetric contacts between the different metals and the
                      ligands should cause a rectifying behavior. However, the
                      diode characteristics remained unobserved due to water
                      molecules adsorbed to the ligand shell, which have an
                      approximately equal binding energy at both metal -molecule
                      contacts. Whereas for Janus AuNPs the targeted, directed
                      asymmetric I/U-characteristic can be proved due to the
                      different transmission coefficients of both
                      molecule-metal-contacts and the significantly different
                      HOMO/LUMO levels of themolecules on both hemispheres. In
                      addition to the tunneling process for the Janus-AuNP
                      devices, thermally activated transport processes were
                      observed under heliumor vacuum atmosphere.},
      keywords     = {Dissertation (GND)},
      cin          = {PGI-7},
      cid          = {I:(DE-Juel1)PGI-7-20110106},
      pnm          = {524 - Controlling Collective States (POF3-524)},
      pid          = {G:(DE-HGF)POF3-524},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/200870},
}