Determination of epitaxial overlayer structures from high-energy electron scattering and diffraction

Abstract

Angle-resolved x-ray photoelectron and Auger data recently obtained by Egelhoff from epitaxially grown Cu on a Ni(001) substrate are analyzed with the use of a single-scattering cluster model. The intensity variations as a function of polar angle are well reproduced by this model, and it permits an analysis of the single-atom origins of the observed peaks. Forward scattering from the first few spheres of neighbors is found to dominate at energies & 900 eV, thus providing detailed information on the early stages of epitaxial growth.

Application of a novel multiple scattering approach to photoelectron diffraction and Auger electron diffraction

“…Considering now the MS results, we find reasonable agreement be~7een the (lx1) and (6x6) curves, especially well off the Going to 4 ML, we note that MS theory predicts too much of a defocussing effect for the scattering along [101], and that SS theory with a reduced attenuation length is actually in better agreement with experiment! The MS curve also has a pronounced higher-order peak about 23°away from the surface normal (67°on the scale of this figure); this is present also in the SS curves, and its more complex origin in forward-scattering plus higher order interference effects has been discussed in a previous analysis of Auger diffraction from epitaxial overlayers by Bullock and Fadley [38].…”

The Study of Surface Structures by Photoelectron Diffraction and Auger Electron Diffraction

“…As noted previously in the discussion of Fig. 22, this is due to the influence of higher orders of interference 71 and perhaps multiple scattering effects. 73 Thus, we conclude that the first 3-4 spheres of neighbors in any lattice will probably produce strong and simply interpretable forward scattering peaks.…”

“…The simple origin of these two peaks has also been directly verified by comparing SSC calculations with and without these important scatterers present. 71 Thus, simple forward scattering peaks from nearest and next-nearest neighbors are very useful in studies of epitaxy, as we have also discussed for the oxide case in the last section. However, the interpretation of weaker features such as those at 4J = 20° and 70° in Fig.…”

Epitaxial film crystallography by high-energy Auger and X-ray photoelectron diffraction

“…However, this phenomenon occurs only for relatively short interatomic spacings. Bullock and Fadley were the first to illustrate these effects by performing model scattering calculations for epitaxial Cu on Ni(001) [55]. In figure 13 we show the essence of these calculations.…”