X-ray diffuse scattering investigation of thin films

X-ray Diffuse Scattering (XDS) is presented, a technique, which determines the roughness, morphology and nanoparticle distribution of thin films. XDS is complementary to X-ray Diffraction and Reflectivity (XRD–XRR). The ability of XDS is demonstrated to investigate the films’ nanoscale surface structure and to determine additional geometrical features such as correlation length and fractal characteristics. It is shown that XDS can be used for the study of the surface morphology, as well as, phase identification of amorphous materials and combined with XRR for quantitative analysis of composite films using the Distorted Wave Born Approximation (DWBA) with the concept that the film surface behaves like a Self-Affined medium. As model systems we study nanocrystalline Boron Nitride (BN) and amorphous Carbon (a-C) films. XDS spectra of BN films containing both cubic and hexagonal phases exhibit two set of Yoneda peaks, located at angles characteristic of the corresponding BN densities, while BN films containing only hexagonal phase exhibit one characteristic set. This indicates that the two BN phases are not atomically mixed. The opposite: strong atomical mixture of sp2 and sp3 components, was found in a-C films by XDS. Additionally, the growth mechanism for a-C films deposited with or without ion bombardment assistance is predicted and discussed.