Excerpt from a much larger image of a Cu2O/Si interface (running from around 7 o'clock to 1 o'clock just to the right of the region shown in the image) in cross-section. This section shows parts of two pyramidal Si mounds on the right, and some fringes from a cuprous oxide column that nucleated between them (followed by columnar growth orthogonal to the substrate silicon wafer, viewed here down <011>).
Sixteen by sixteen darkfield decomposition of this image, for comparison with periodicities in the Fourier transform below, so as to determine the spatial origins of those periodicities in the field of view. In the center is the reduced-resolution bright field image. The outlying orange circles, associated with a weak Cu2O (040) spacing of only 1.065 Angstroms in the original image, were discovered to be associated with the main Cu2O (200) spacing from a look for spatial correlations in this image. This confirms that the Cu2O lattice seen higher in the specimen, whose (200) direction is tilted by about 4 degrees off the Silicon (100) surface normal, even at this very base of the growth column is part of a Cu2O single crystal showing cross-fringes in confirmation. This observation also makes this the second image we have which, after some careful filtering, might allow inspection of the epitaxy for evidence of dislocations at points of Cu2O/Si contact.
This is the power spectrum of the image at top, with periodicities labeled whose spacing and angles can be measured here, and whose spatial origin can be determined from the darkfield decomposition.