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 (002) reflection. We apply an off-axis imaging condition with the (002) 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 (000) and the amplitude of the (002) 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 (000) and (002) reflections are taken into account. The application of the procedure is demonstrated with an AlAs/GaAs(001) 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.
Original language | English |
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Pages (from-to) | 51-61 |
Number of pages | 11 |
Journal | Ultramicroscopy |
Volume | 88 |
Issue number | 1 |
DOIs | |
State | Published - Jun 2001 |
Keywords
- Chemical sensitive reflection
- Compositional analysis
- Electron holography