title: Compositional analysis based on electron holography and a chemically sensitive reflection.
abstract: A method for compositional analysis of low-dimensional heterostructures is presented. The suggested procedure is based on electron holography and the exploitation of the chemically sensitive (0 0 2) reflection. We apply an off-axis imaging condition with the (0 0 2) beam strongly excited and centered on the optic axis. The first side band of the hologram is centered using an "empty" reference hologram obtained for a hole of the specimen. From the centered side band we use the phase of the central (0 0 0) and the amplitude of the (0 0 2) reflections to evaluate the local composition and the local specimen thickness in an iterative and self-consistent way. Delocalization effects that lead to a shift of the spatial information of (0 0 0) and (0 0 2) reflections are taken into account. The application of the procedure is demonstrated with an AlAs/GaAs(0 0 1) superlattice with a period of 5 nm. The concentration profiles obtained are discussed in relation to segregation. The measured segregation efficiency is R = 0.51 +/- 0.02.
authors.affiliation: EMAT, University of Antwerp, Belgium. rosenaue@lemming0.lem.uni-karlsruhe.de
authors.forename: A
authors.initials: A
authors.lastname: Rosenauer
authors.forename: D
authors.initials: D
authors.lastname: Van Dyck
authors.forename: M
authors.initials: M
authors.lastname: Arzberger
authors.forename: G
authors.initials: G
authors.lastname: Abstreiter