The structure analysis of nano-structured surfaces has become more and more important in the last years due to the strongly increasing field of nanotechnology and surface science. Direct imaging techniques are often used to characterize the surface morphology and the lateral spacings of such structures. The limitations of this methods are the very small observable area and the inability to determine buried and inner structures. Here, small angle x-ray scattering under grazing incident angles (GISAXS) is a very powerful tool. With this method one is able to determine sample surface structures as well as inner electron density fluctuations of the deposited material.

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In the last years the number of GISAXS investigations increased owing to the ability to perform such experiments at many experimental stations at synchrotron radiation sources. The method is now well established and the angular resolution of the scattering experiments is improved by using smaller beam sizes with low divergence. For the investigation of coatings, films and particles on surfaces, the GISAXS method has several important advantages over transmission scattering techniques. A highly intense scattering pattern is always obtained, even for films of nanoscale thickness, because the x-ray beam path length through the film plane is sufficiently long. The detectable length scales from a few to hundreds of nanometers are not limited by a beamstop which covers the information near qy = 0 due to the possibility to perform so-called out-of-plane scans in GISAXS geometry. There is a reduced bulk scattering from the substrate due to the limited penetration depth of the incoming beam at glancing angles near the critical angle of the substrate on which the film is deposited. The sample preparation methods like spin- or dip-coating, simple drop-casting or sputtering techniques are well established. GISAXS can be applied to determine internal morphologies of thin films as well as top surface morphologies of films, coatings and substrates.

Contents provided by Dr. A. Meyer - Institute of Physical Chemistry - University of Hamburg