Growth studies of hetero-epitaxial thin films with x-rays

Heteroepitaxial growth of lanthanide-metal films on W(110) was investigated with x rays. Lanthanide-metal films growth with high crystalline quality, revealing extended growth oscillations in the specularly reflected intensity. Furthermore, these systems are characterized by a sharp interface and are very well suited to investigate the specific characteristics of x rays in the study of heteroepitaxial growth. These characteristics include the dependence of the growth-oscillation period on the scattering vector in specular geometry and the influence of layer relaxations at the interface. Due to the large penetration depth of the x rays compared to the film thickness, details such as amplitudes and phases of the growth-oscillation curves are determined by the structure of the substrate/film interface during the whole growth process. The possibilities to obtain information about the interface structure from an analysis of the growth-oscillation curves are discussed.