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@PHDTHESIS{Mai:58946,
      author       = {Mai, Yaohua},
      title        = {{M}icrocrystalline silicon layers for thin film solar cells
                      prepared with {H}ot {W}ire {C}hemical {V}apour {D}eposition
                      and {P}lasma {E}nhanced {C}hemical {V}apour {D}eposition},
      volume       = {4254},
      issn         = {0944-2952},
      school       = {VR Chin. Tianjin},
      type         = {Dr. (Univ.)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-58946, Juel-4254},
      series       = {Berichte des Forschungszentrums Jülich},
      pages        = {144 p.},
      year         = {2007},
      note         = {Record converted from VDB: 12.11.2012; Tianjin, VR China,
                      Nankai Univ., Diss., 2006},
      abstract     = {High rate growth process, material quality and related
                      solar cell performance of hydrogenated microcrystalline
                      silicon ($\mu$c-Si:H) were investigated in this work. High
                      deposition rate (R$_{D}$) was achieved by very high
                      frequency (VHF) plasma-enhanced chemical vapor deposition
                      (PECVD) working at high pressure and high power (hphP).
                      Compared to the $\mu$c-Si:H material deposited with
                      conventional low pressure, low power (lplP), the hphP films
                      showed equivalent optical and electrical properties,
                      indicating their abilities as absorbers in thin film silicon
                      solar cells. The influences of the deposition parameters on
                      the solar cell deposition rate and performance were
                      systematically investigated in this thesis. It was found
                      that optimum cells were always found close to the transition
                      from highly microcrystalline to the amorphous growth and
                      with medium crystallinity. Variations of many deposition
                      parameters can tune the crystallinity. Among them, varying
                      silane concentration (SC) is the most easy and
                      straightforward way. Under optimized conditions, high
                      efficiency of 9.8\% was obtained at RD over 1 nm/s for a
                      single junction p-i-n solar cell. Efforts were also made to
                      find out the correlation between the material properties and
                      solar cell performance. The Raman structure depth profile
                      method revealed that hphP solar cells consisted of a more
                      amorphous incubation layer at the p/i interface, which was
                      found to reduce the short wavelength light response of the
                      solar cells. Besides PECVD, Hot Wire (HW) CVD is an
                      alternative method for $\mu$c-Si:H deposition. It was found
                      that HWCVD $\mu$c-Si H cells showed higher V$_{OC}$ and FF
                      than the PECVD cells in a wide range of i-layer
                      crystallinity. This was attributed to the better p/i
                      interface quality in the HWCVD cells. Inserting an intrinsic
                      microcrystalline p/i interface layer deposited by HWCVD into
                      PECVD cells nearly eliminated the above differences. Raman
                      structure depth profile, transmission electron microscopy
                      and selective area electron diffraction were applied to
                      investigate the structure properties of the solar cells.
                      However, differences could hardly be found in the already
                      homogeneous i-layers of PECVD and HWCVD cells. Thus the
                      positive effect of the HW-buffer for facilitating nucleation
                      was not observed. An amorphous HW-buffer layer in PECVD
                      cells resulted in a more amorphous p/i interface and an
                      increasing crystallinity along the growth axis. However,
                      such amorphous interface layer still enhanced the V$_{OC}$
                      and FF of the resulting cells. Therefore, it was concluded
                      that structure homogeneity was not the reason for the better
                      performance of the HWCVD cells. Applying the HW-buffer
                      concept to the PECVD hphP cells, we obtained a high
                      efficiency of 10.3\% at a high R$_{D}$ of 1.1 nm/s. This is
                      the highest efficiency reported so far for the single
                      junction $\mu$c-Si:H solar cells in p-i-n configuration.},
      cin          = {IEF-5},
      cid          = {I:(DE-Juel1)VDB813},
      pnm          = {Erneuerbare Energien},
      pid          = {G:(DE-Juel1)FUEK401},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/58946},
}