X-ray standing waves in a heterostructure: application to a Zn(1-x)CoxO epilayer on ZnO(00.1)-O substrate.

X-ray standing waves (XSW) in a thin epitaxic film are treated in the framework of the dynamical theory. It is demonstrated that the fluorescence yield around the main peak of the rocking curve has essentially the same characteristics as that of the usual XSW on a bulk crystal surface. Thus, XSW provide a direct method to probe the atom position in a thin film.