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@INPROCEEDINGS{Schierholz:155251,
      author       = {Schierholz, Roland and Duchamp, Martial and Asunción and
                      Godinho and Caballero},
      title        = {{S}pectrum imaging of {H}elium pores in amophous
                      {S}ilicon-coatings},
      school       = {Instituto de Ciencia de Materiales de Sevilla},
      reportid     = {FZJ-2014-04425},
      year         = {2014},
      abstract     = {In order to probe the helium distribution in porous
                      amorphous coatings of silicon grown by magnetron, we present
                      an extraction method of the Helium signal obtained from
                      STEM-EELS spectrum images [1]. The goal of the work is to
                      get a rough estimation of the Helium pressure inside the
                      pores and correlate this to the deposition parameters. For
                      this we modified the procedure described by Walsh [2] and
                      David et al. [3] and integrated this in MATLAB. With our
                      present architecture it is possible to read in images in dm3
                      format recorded on a with DigiScan by Gatan and undergo
                      several data treatment. For our purpose we selected
                      centering the zero loss peak and integrating it,
                      deconvolution, fitting of the plasmon intensity with one
                      narrow peak at ≈ 23 eV attributed to the Silicon bulk
                      plasmon and a wider one at ≈ 24 to 25 eV to adapt
                      contributions from surface oxide layer and carbon
                      contamination, and fitting of the residual intensity arsing
                      from the He-K edge at ≈ 22 eV with a gaussian. Part of the
                      procedure is visualized in Figure 2, which shows two spectra
                      from the same spectrum image one at the matrix position
                      (Figure 2 (a)) and the other at the pore center (Figure 2
                      (b)). The spectra were are already deconvoluted and the fit
                      to the Silicon plasmon is plotted red and the fit for the
                      SiO2 and the carbon contamination is plotted green. For both
                      positions the fit is satisfactory and for the pore position
                      and also the residual signal around 22 eV is well described
                      by the gaussian fit.The procedure allows to plot maps of all
                      fitting parameters and also to extract EFTEM images. Figure
                      1 shows (a) thickness map (b) the gaussian integral and (c)
                      the gaussian peak position for a selected spectrum image of
                      a single pore. The Helium density can be derived in two
                      ways, from the ratio of the Helium K-edge intensity/ to the
                      ZLP-intensity and by the energy shift of the edge position.
                      Both methods suffer from large errors around 30 $\%$ so the
                      cross check is an advantage. We will complete our results by
                      additional tomography experiments and correlate them to
                      compositional depth profiles measured with Rutherford
                      backscattering.},
      month         = {Jul},
      date          = {2014-07-07},
      organization  = {3rd European Conference on NanoFilms
                       $\&$ Al-NanoFunc final Conference:
                       Microstructural and chemical
                       chracterization in the nanoscale.,
                       Sevilla (Spain), 7 Jul 2014 - 11 Jul
                       2014},
      subtyp        = {Other},
      cin          = {IEK-9},
      cid          = {I:(DE-Juel1)IEK-9-20110218},
      pnm          = {123 - Fuel Cells (POF2-123)},
      pid          = {G:(DE-HGF)POF2-123},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/155251},
}