He Diffraction from Semiconductor Surfaces

Abstract

The study of the Si(100) surface has proven to be an interesting start to the development of He diffraction into a quantitative structural tool for semiconductor surfaces. Several aspects of the problem have become better defined. For corrugated surfaces, simple scattering theories such as the eikonal or sudden approximation are not adequate, in particular in their treatment of multiple scattering, i.e. the diffraction probabilities are strongly coupled. However, they do allow qualitative features of the potential to be described. An accurate computation of the diffraction intensities for realistic potentials is a substantial undertaking. The attractive potential must be well understood as the phase shift variation over the unit mesh is large and the potential energy may also vary significantly over the unit mesh. A problem specific to the Si(100) is the lack of long range order in the secondary reconstruction which makes accurate comparison with theory difficult.