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@PHDTHESIS{Dylla:44172,
      author       = {Dylla, Thorsten},
      title        = {{E}lectron {S}pin {R}esonance and {T}ransient
                      {P}hotocurrent {M}easurements on {M}icrocrystalline
                      {S}ilicon},
      volume       = {43},
      school       = {Freie Universität Berlin},
      type         = {Dr. (Univ.)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-44172},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Energietechnik / energy technology},
      pages        = {X, 138 S.},
      year         = {2004},
      note         = {Record converted from VDB: 12.11.2012; Freie Universität
                      Berlin, Diss., 2004},
      abstract     = {The electronic properties of microcrystalline silicon
                      (μc-Si:H) films have been studied using electron spin
                      resonance (ESR), transient photocurrent time-of-flight (TOF)
                      techniques, and electrical conductivity measurements.
                      Structural properties were determined by Raman spectroscopy.
                      A wide range of structure compositions, from highly
                      crystalline films with no discernable amorphous content, to
                      predominantly amorphous films with no crystalline phase
                      contributions, was investigated. Models and possible
                      explanations concerning the nature and energetic
                      distribution of electronic defects as a function of film
                      composition are discussed. It is shown that the spin density
                      N$_{S}$ in μc-Si:H films is linked strongly to the
                      structure composition of the material. The highest N$_{S}$
                      is always found for material with the highest crystalline
                      volume fraction. With increasing amorphous content, N$_{S}$
                      decreases, which is attributed to increasing hydrogen
                      content and improved termination of dangling bonds.
                      Moreover, the amorphous phase content, incorporated between
                      the crystalline columns, appears to act as a passivation
                      layer, leading to more effective termination of unsatisfied
                      bonds at the column boundaries. Both reversible and
                      irreversible changes in the ESR signal and dark conductivity
                      due to atmospheric effects are found in μc-Si:H. These are
                      closely connected to the structure composition, in
                      particular the active surface area. The porous structure of
                      highly crystalline material facilitates in-diffusion of
                      atmospheric gases, which strongly affects the character
                      and/or density of surface states. Two contributing processes
                      have been identified, namely adsorption and oxidation. Both
                      processes lead to an increase of N$_{S}$. In the case of
                      adsorption the increase is identified as arising from
                      changes of the db2 resonance (g=2.0052), while the intensity
                      of the db1 resonance (g=2.0043) remains constant. With
                      increasing amorphous content the magnitude of both
                      adsorption and oxidation induced changes decreases, which
                      may be linked to the greater compactness of such films.
                      Measurements on n-type μc-Si:H films were used as a probe
                      of the density of gap states, confirming that the spin
                      density NS is related to the density of defects. The results
                      confirm that for a wide range of structural compositions,
                      the doping induced Fermi level shift in μc-Si:H is governed
                      by compensation of defect states, [...]},
      cin          = {IPV},
      cid          = {I:(DE-Juel1)VDB46},
      pnm          = {Photovoltaik},
      pid          = {G:(DE-Juel1)FUEK247},
      typ          = {PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/44172},
}