Q-DEPENDENCE OF THE GROWTH-OSCILLATION PERIOD OF X-RAY REFLECTIVITY IN HETEROEPITAXY - HO W(110)/

We report on pronounced oscillations of the specular x-ray reflectivit y as a function of deposited material in epitaxial growth of Ho on W(1 10). In specular geometry, the periods of these growth oscillations ar e found to scale inversely with the length of the scattering vector q. This behavior is shown to be characteristic for heteroepitaxial growt h, while in homoepitaxy the oscillation period is independent of q. Th e q dependence has to be accounted for in growth studies with x rays, in particular when growth-oscillation periods are related to the numbe r of deposited layers.