Surface structural sensitivity of convergent-beam RHEED: Si (001)2x1 models compared with dynamical simulations

The aim of this work is to evaluate the sensitivity of convergent-beam RHEE D for the refinement of surface atomic structure. We have compared experime ntal and theoretical convergent-beam RHEED patterns from the silicon (0 0 1 ) reconstructed surface. The experiment was carried out in a custom designe d UHV diffraction camera,using a micron sized probe. Both experimental and theoretical CB-RHEED patterns show complex details, highly sensitive to the surface structure. The multiple scattering simulations were based on two e xperimental structural models which make different assumptions for dimer ti lt, one derived from X-ray diffraction results, and another from LEED data. The simulated CB-RHEED patterns using the X-ray model were found to be in closer agreement with our experiment than the LEED model. However, the agre ement is not entirely satisfactory, suggesting that further improvement on this model is necessary. (C) 2000 Elsevier Science B.V. All rights reserved .