PROFILE ANALYSIS OF THIN-FILM X-RAY-DIFFRACTION PEAKS

In this study, we have analysed the X-ray diffraction peak profiles of thin films using the two main models usually applied to bulk material s: the integral width and the Warren-Averbach method, in thin films, t he structure is nanocrystalline leading to diffraction peak profiles v ery different from those found in the bulk. Consequently, the applicat ion of the usual deconvolution models sometimes gives erroneous result s, such as negative microdistortions or coherently diffracting domains sizes. This is probably due to the hypothesis underlying the models o r/and to the difficulties to perform a good profile Fourier transform due to a poorly defined background. The case of gold, platinum and tun gsten thin films are considered. The microdistortions are very importa nt (up to 5 X 10(-3)) compared with those of a heavily cord worked bul k materials (10(-3)) and the size of their coherently diffracting doma ins is nanometric (2-20 nm). The discussion of these results suggests some new directions for research in this area.