engleski

GISAXS and WAXS analysis of amorphous-nanocrystalline silicon thin films

The amorphous-nanocrstalline silicon thin film multilayer structures were deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) on the glass or glass + SnOx substrate with various silicon nanocrystal size distributions and volume fractions. The samples were examined by Grazing Incidence Small Angle X-ray Scattering (GISAXS) and Wide Angle X-ray Scattering (WAXS) at the Austrian SAXS beamline (Synchrotron Elettra, Trieste) using X-ray beam energy of 8 keV. The grazing incidence angle varied from the critical angle to 0.02 deg. above the critical angle. This allowed the examination of the samples at different depth and distinguished surface scattering contribution from particles scattering in bulk. Contribution of surface scattering was estimated using results of Atomic Force Microscopy (AFM) image roughness analysis. Sizes of “ particles” calculated from horizontal and vertical sections of 2D GISAXS patterns were between a 2 and 20 nanometers. Since GISAXS is sensitive to electron density difference (contrast) between the scattering bodies and the surrounding matrix, it is not evident whether the particles are nanocrystals or just voids embedded in amorphous matrix. However, the size of crystals calculated from analysis of peaks line-shape in WAXS spectra and crystal size distribution obtained from HRTEM images agree well with size of “ particles” estimated from GISAXS, strongly indicating that observed particles are silicon nanocrystals.

amorphous-nanocrytalline silicon; GISAXS; GIWAXS; HRTEM; nanoparticles

nije evidentirano