RIGOR, AND PLAN-VIEW SIMULATION OF SURFACES

This paper discusses the rigor of simulating plan-view images of surfaces using numerical multislice calculations. In particular, the validity of using a conventional multislice approach with individual atomic slices is tested versus a three-dimensional muitislice with the top and bottom surfaces specifically included; the result is that the two are identical when inelastic scattering is neglected and almost identical when it is included. These results also demonstrate that inelastic scattering cannot be neglected for surface plan-view simulations. For instance, the bulk-forbidden, surface-allowed spots are shown to correspond to true bulk Bloch waves which are damped in thicker crystals consistent with experimental observations. The existence of a strong top-bottom effect is also pointed out, which means that plan-view imaging is more sensitive to the bottom surface except in exceedingly thin crystals.