Back-reflection images obtained from single-crystal semiconductor substrates using Laue microdiffraction with medium-to-high energy x rays may contain double spots, one strong and one weak, for the higher-energy reflections. Some of the weaker spots originate from the back surface of the sample and are due to dynamic diffraction from a finite crystal. Others may be due to epitaxial thin films on the substrate. The intensity and position of the back-surface peaks depend on the x-ray energy, sample characteristics, and diffraction geometry. We provide a set of simple equations that can be used to calculate the separation of such peak pairs. These equations can be used to identify the peaks from the back surface of the sample.
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We also scanned the detector equipped with an analyzer crystal. The secondary peak from the exit surface could not be detected in this case because it was almost parallel with the primary peak.
The last data point in Fig. 7(a), where , was measured with the length dimension of the sample strip rotated to be parallel to the incident beam.
In such a case, as the beam approaches a highly strained region, the penetration depth would also change.
