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Compositional analysis based on electron holography and a chemically sensitive reflection
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| Abstract |
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| 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. (C) 2001 Elsevier Science B.V. All rights reserved. |
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| Language |
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English
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| Source (journal) |
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Ultramicroscopy. - Amsterdam |
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| Publication |
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Amsterdam : 2001
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0304-3991
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88:1(2001), p. 51-61
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| ISI |
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000168940900005
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