RHEED wave functions and the effect of reconstruction on secondary electron emission from the Si(1 0 0) surface

The effect of surface reconstruction on contrast in scanning electron microscopy of the Si(1 0 0)-2 × 1 surface is investigated. A theory of the initial secondary production rate is developed and an upper bound on the rate is shown to depend on the product of the integrated intensities of the initial and final RHEED states. These states are calculated with a reflection matrix method and their depth dependence is investigated. The results are used to analyse scanning electron microscopy contrast in images of 1 × 2- and 2 × 1-regions of the Si(1 0 0)-2 × 1 surface reported by Watanabe et al. The calculated integrated intensities are consistent with the experimental images and with the experimentally observed dependence of the contrast on the azimuth of the incident electron beam. This supports the idea that the observed contrast is caused by the effect of surface reconstruction on the RHEED states.