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Figure 18
(a) A diffraction space map close to the 004 reflection from an InGaAs structure grown epitaxially onto a GaAs substrate. The data were collected with the beam selection diffractometer (Fewster, 2004BB12), with a single reflection 004 analyser crystal (stepping in Ω followed by a scan with movements in Ω and 2θ maintaining a 1:2 ratio). The strong fringing is associated with the layer structure (the shape transform) and occurs along the crystal surface normal. The streak where 2θ = 2Ω corresponds to the incident-beam divergence and the streak along 2θ for a constant Ω value corresponds to the detector acceptance range (in this case the diffraction profile of the analyser crystal). The remaining streak at constant 2θB for varying Ω values is the `enhancement' peak for the substrate (as in Fig. 4[link]b).

ISSN: 2053-2733
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