Effect of Surface Plasmons on Energy Filtered RHEED Rocking Curves from a Si(111)-7×7 Surface

Abstract

Energy filtered (EF) RHEED rocking curves of the specular beam from the Si(111)‐7×7 surface in the [112‐] azimuth have been measured and analyzed by means of a dynamical calculation of two‐dimensional (2D) Bloch waves taking account of the surface plasmon loss. It is demonstrated that the surface plasmon loss plays an important role in the explanation of RHEED rocking curves. The effect of the surface plasmon loss does not decrease in a simple way as the glancing angle increases and is classified into two groups depending on the localization of the Bloch wave field.

New approaches to the imaging of surface potentials

“…But this limited range is compensated by the higher information content of the two-dimensional CB-RHEED pattern compared to the conventional one-dimensional rocking curve. The changes in relative intensities after elastic filtering observed in [27] occur in the direction of the reciprocal rods normal to the surface and seem to be only appreciable when the intensity is recorded along a large portion of the rod. Since our findings so far show no significant change of the shape of elastic linescans through CB-RHEED discs compared to the unfiltered scans and because of the high sensitivity of the CB patterns to changes in the surface structure, it may be possible to refine atomic positions from CB-RHEED patterns based on pattern matching only, without energy filtering.…”

“…A smaller probe size is therefore highly desirable. The calculated intensities depend strongly on the imaginary potential used to treat surface plasmon losses [26,27]. We use in this calculation an empirical mean absorption potential of the form [28]…”

“…The values used here are V 0 = 1, a = 0.5. It has recently been observed experimentally that elastic filtering changes the relative intensities of rocking curves and that incorporation of an extended absorption potential into calculations to account for plasmon losses can lead to shifts in rocking curve maxima [27]. Therefore, further study of the surface plasmon influence on the elastic rocking curve is necessary for quantitative analysis of RHEED intensities.…”