engleski

Modeling of 2D GISAXS of nano-crystalline silicon thin films

Grazing-Incidence Small-Angle X-ray Scattering (GISAXS) spectra of nano-crystalline silicon thin films were simulated using the freely available FORTRAN program IsGISAXS. This program calculates the particles form factor in the distorted-wave Born approximation, which describes correctly the reflection-refraction effects at the substrate surface. In model calculations, the samples were assumed as a mixture of random oriented nano-crystals and voids 2-30 nm in size, embedded in an amorphous matrix. Several particle shapes and size distributions were tested using, as initial values in the calculation, the data estimated by HRTEM . The calculated spectra were compared with GISAXS measurements done at the Austrian SAXS line at the synchrotron Elettra (Trieste). By varying the initial values in, the calculated, spectra were fitted to the experimental values until a reasonable match was obtained. The in that way obtained individual particle sizes, size distribution and volume contribution of each element used in the model calculation were compared with the results from Raman and optical spectroscopy. GISAXS was performed at different grazing incidence angles which allows for depth resolution and enables a better comparison with the other applied methods. The obtained results and usefulness of the described procedure in the analysis of thin films will be discussed.

GISAXS; nano-crstalline silicon; HRTEM

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