Dynamical Scattering Effects at Grazing Incidence Conditions

Abstract

In the previous chapter, X-ray diffuse scattering from free-standing nanoscale islands was simulated exclusively by using the simple kinematical theory. The corresponding experiments were carried out at large angles of incidence $\alpha_i$ compared with the critical angle of total external reflection so that refraction effects and the influence of the specularly reflected wave could be neglected. However, for grazing-incidence/exit scattering geometries such as GISAXS and GID these dynamical effects have to be taken into account, and the simulations have to be performed in the framework of the distorted-wave Born approximation. In order to visualize these dynamical effects, the model system of LPE-grown SiGe islands described in Chap. was again chosen. These islands are especially suitable, owing to their high perfection regarding uniform shape and size. Moreover, they are large enough to give a sufficiently high scattering signal. This enables us to qualitatively and quantitatively check the validity of the DWBA approach.