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@ARTICLE{Cao:841772,
      author       = {Cao, Zhao and Ermes, Markus and Lehnen, Stephan and Carius,
                      Reinhard and Bittkau, Karsten},
      title        = {{E}ffect of topography-dependent light coupling through a
                      near-field aperture on the local photocurrent of a solar
                      cell},
      journal      = {Physical chemistry, chemical physics},
      volume       = {20},
      number       = {2},
      issn         = {1463-9084},
      address      = {Cambridge},
      publisher    = {RSC Publ.},
      reportid     = {FZJ-2018-00076},
      pages        = {1098 - 1104},
      year         = {2018},
      abstract     = {An aperture-type scanning near-field optical microscope
                      (a-SNOM) is readily used for the optical and optoelectronic
                      characterizations of a wide variety of chemical, biological
                      and optoelectronic samples with sub-wavelength optical
                      resolution. These samples mostly exhibit nanoscale
                      topographic variations, which are related to local material
                      inhomogeneity probed either by an optical contrast or by
                      secondary effects such as photoconductivity or
                      photoluminescence. To date, in the interpretation and
                      evaluation of the measurement results from a-SNOM or derived
                      methods, often only the local material inhomogeneity is
                      taken into account. A possible influence of the optical
                      interaction between the scanning probe and the surface
                      topography is rarely discussed. In this paper, we present
                      experimental and theoretical investigation of the effects of
                      nanoscale topographic features on a-SNOM measurement
                      results. We conduct local photocurrent measurements on a
                      thin-film solar cell with an a-SNOM as the illumination
                      source. A clear correlation between the photocurrent
                      response and local topography is observed in all
                      measurements with a signal contrast of up to $~30\%,$
                      although the sample features homogeneous permittivity and
                      electrical properties. With the help of finite-difference
                      time-domain (FDTD) simulations, this correlation is
                      reproduced and local light coupling is identified as the
                      mechanism which determines the local photocurrent response.
                      Our results suggest that a-SNOM-based measurements of any
                      sample with material inhomogeneity will be superimposed by
                      the local light-coupling effect if surface topography
                      variation exists. This effect should always be taken into
                      consideration for an accurate interpretation of the
                      measurement results.},
      cin          = {IEK-5},
      ddc          = {540},
      cid          = {I:(DE-Juel1)IEK-5-20101013},
      pnm          = {121 - Solar cells of the next generation (POF3-121) /
                      CHEETAH - Cost-reduction through material optimisation and
                      Higher EnErgy outpuT of solAr pHotovoltaic modules - joining
                      Europe’s Research and Development efforts in support of
                      its PV industry (609788)},
      pid          = {G:(DE-HGF)POF3-121 / G:(EU-Grant)609788},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:29238764},
      UT           = {WOS:000419219700041},
      doi          = {10.1039/C7CP06783F},
      url          = {https://juser.fz-juelich.de/record/841772},
}