The role of plasmon scattering in the quantitative contrast analysis of high-resolution lattice images of GaAs

摘要

We compare unfiltered, energy filtered zero loss and plasmon loss high-resolution lattice images from a cleaved GaAs wedge specimen. The filtered zero loss images exhibit lower lattice fringe amplitudes than the unfiltered images which can be explained only by the contributions of the plasmon images (whether coherently or incoherently) to the contrast being in phase with the filtered zero loss image contrast. The contrast maxima of the (200) lattice fringes occur at the same specimen thicknesses in the plasmon and zero-loss images, suggesting that the elastic and the plasmon scattering are coherently related at least for thicknesses up to 30nm.