Scanning Microscopy


A new formulation is presented for the use of crystallographic orientation effects in electron scattering to determine impurity lattice location. The development of electron channeling techniques is reviewed and compared to high energy ion channeling and to the Borrmann effect in x-ray diffraction. The advantages of axial over planar geometry are discussed. Delocalization effects are more serious for quantitative analysis than have generally been believed. The new formulation applies to any crystal lattice and quantitatively includes delocalization effects via c-factors, which have been experimentally determined for diamond structure semiconductors. For sublattice site location this formulation removes the two major approximations of the original ALCHEMI formulation, namely that all the inner shell excitations are perfectly localized, and that all of the impurity atoms occupy distinct crystallographic sites. As an example, we study the location of small perfectly coherent Sb precipitates within the Si lattice.

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