![]() ![]() The extraction of structural information from Laue oscillations has been challenging due to the lack of a discussion of all relevant physical phenomena in a single reference that relates structural parameters to Laue intensities and provides examples illustrating the development of structural models from experimental data. In addition, the number of Laue oscillations observed on either side of the Bragg reflection varies significantly from sample to sample, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,. The Laue function results in symmetric intensities of satellite reflections on either side of the Bragg maxima, but an asymmetric distribution of intensities on each side is also frequently observed. Furthermore, the intensity of experimental Laue oscillations often differs from those predicted from the Laue function. In these reports, differences between the total film thickness calculated from Kiessig fringes in the XRR data and the thickness of the crystalline layers obtained via the Laue oscillations were found. There are only a few reports in the literature where both the oscillations in the X-ray reflectivity (XRR) at low diffraction angles and the Laue oscillations observed in the vicinity of a Bragg reflection are used to detect potential excess material. The thickness obtained in this manner is often taken to be the total film thickness, which assumes that there is no additional thickness from amorphous or non-crystallographically aligned layers present above and/or below the diffracting crystal. The most common quantitative analysis of Laue oscillations utilizes an equation derived from the Laue interference function to extract the total thickness of the crystalline phase, ,, ,, ,, ,. While it is true that Laue oscillations are a qualitative indicator of sample quality, the presence of Laue oscillations also provides an opportunity to gain significant structural information about films. The presence of Laue oscillations is frequently used as evidence of “the high crystallinity of samples”, “the uniformity of the film and smoothness of the interfaces”, or that “the out-of-plane order is high and coherent over the entire film thickness”. Generally, the presence of Laue oscillations are taken as confirmation that grown films are of high quality, homogenous, contain only the targeted compound, and have smooth and planar top and bottom interfaces, ,, ,, ,,. First predicted by Max von Laue, the Laue interference function relates the number of unit cells in the diffracting crystal to the distribution of diffracted intensity. Laue oscillations result from the incomplete destructive interference of a finite number of unit cells and occur when a sample consists of domains with the same number of unit cells across most of the area being probed. ![]()
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