DYNAMICAL THEORY OF RHEED FROM STEPPED SURFACES

A general analysis is presented of the calculation of reflection high energy electron diffraction (RHEED) from surfaces which are not monatomically flat. The specific case discussed is that of surfaces during epitaxial growth. The scattering due to the surface layer may be divided into the effect of the average potential, which can be treated accurately by fully dynamical calculations, and the disordered part, which to a good approximation can be treated by first order perturbation theory. It is found that the averaged potential contribution dominates the oscillations observed during the growth of successive monolayers and that the diffuse scattering has two components arising from the spread in the shapes and sizes of islands and from the distribution of islands on the surface. It is shown that the analysis is readily extended to cover the case of three-dimensional island growth. The relationship between this approach and some earlier studies is established.