Dynamical calculation of high-resolution reflection electron microscopy lattice fringes from the Si(111)7 × 7 surface

Abstract

High-resolution reflection electron microscopy (HR-REM) lattice fringes for the flat Si(111)7 × 7 surface are simulated using our earlier reported theory of REM image formation. This simulation procedure employs a 2D Bloch wave formulation of dynamical (multiple scattering) elastic reflection high-energy electron diffraction (RHEED) theory combined with conventional electron microscopy (Abbé) imaging theory. One of the purposes of this study is to provide the first critical comparison of HR-REM images simulated using this procedure with experimental images for the Si(111)7 × 7 surface. It is found that it is possible to reproduce in the simulations all of the fringe periodicities observed in real HR-REM images from this surface. The incorporation into the simulation procedure of the effects of primary electron beam divergence and chromatic aberration is described in detail. The primary beam divergence is essential to reproduce in simulated images the correct defocusing behaviour. When these details are incorporated, the simulation procedure gives good agreement with experiment. This work shows that quantitative HR-REM image simulation constitutes a valuable interpretative tool to be used in support of experimental HR-REM. Published by Elsevier Science B.V.