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@PHDTHESIS{Schfer:283566,
      author       = {Schäfer, Anna},
      title        = {{G}rowth and characterization of crystalline rare-earth
                      based thin oxide films for the application as gate
                      dielectric in nanotechnology},
      volume       = {46},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2016-01880},
      isbn         = {978-3-95806-111-8},
      series       = {Schriften des Forschungszentrums Jülich. Reihe Information
                      / Information},
      pages        = {xiii, 157 S.},
      year         = {2015},
      note         = {RWTH Aachen, Diss., 2015},
      abstract     = {For standard metal oxides semiconductor (MOS) field effect
                      transistors (FETs), but also for any other MOS based device
                      appropriate gate dielectrics are needed. Such dielectrics,
                      usually oxides, need to exhibit good layer quality and
                      stability, good insulating properties and typically high
                      permittivities. The aim of this work is to develop new
                      oxides for the use in standard Si transistors on the one
                      hand and for GaN based devices such as high electron
                      mobility transistors on the other hand. For Si MOSFETs a
                      standard atomic layer deposition (ALD) HfO$_{2}$ process is
                      extended to dope HfO$_{2}$ with Al and Lu. After process
                      optimization Hf$_{0.89}$Al$_{0.11}$O$_{2-\Delta}$ and
                      Hf$_{0.8}$Lu$_{0.2}$O$_{2-\Delta}$ transform into a
                      polycrystalline layer with large fractions of a high $\
                      kappa$ phase of HfO$_{2}$, most probably the cubic one, and
                      exhibit permittivities of 30 and 33, respectively. All
                      layers are smooth, the density of interface traps hardly
                      changes due to doping and leakage current densities for
                      Hf$_{0.8}$Lu$_{0.2}$O$_{2-\Delta}$ are as low as
                      10$^{0}8$A/cm$^{2}$ for an equivalent oxide thickness of 1.5
                      nm. For the application on GaN, crystalline GdScO$_{3}$ and
                      LaLuO$_{3}$ are investigated. Calculations on GdScO$_{3}$
                      reveal that the orthorhombic and cubic form of GdScO$_{3}$
                      have almost equal energies of formation while a hexagonal
                      crystal has a 500 eV per formula unit enhanced energy. Even
                      though the energy of formation is fairly high, the novel
                      hexagonal forms of GdScO$_{3}$ and LaLuO$_{3}$ could be
                      stabilized by pulsed laser deposition on GaN and on
                      Y$_{2}$O$_{3}$ on Si(111) which is used as alternative
                      growth template with hexagonal geometry. Thus the nature of
                      the substrate (polar/ non-polar) apparently determines the
                      structure of the oxide formed. Further analysis shows that
                      the two growth templates can promote the hexagonal or the
                      cubic forms of GdScO$_{3}$ and LaLuO$_{3}$ depending on
                      growth temperature and Y$_{2}$O$_{3}$ layer thickness.
                      Relative permittivities of approximately 26 are extracted
                      for both hexagonal GdScO$_{3}$ and hexagonal LaLuO$_{3}$.
                      All known phases of the two oxides have band gaps above 5 eV
                      which is important for the use as gate dielectric, e.g. to
                      minimize tunneling currents. Current voltage measurements
                      reveal leakage current densities of 1.2 X 10$^{-8}$
                      Acm$^{-2}$ at 1V for $\textit{EOT}$ = 3nm and a dielectric
                      breakdown above 2MVcm$^{-1}$ for hexagonal GdScO$_{3}$ on
                      GaN.},
      cin          = {PGI-9},
      cid          = {I:(DE-Juel1)PGI-9-20110106},
      pnm          = {521 - Controlling Electron Charge-Based Phenomena
                      (POF3-521)},
      pid          = {G:(DE-HGF)POF3-521},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/283566},
}