X-ray study of the superstructure in heavily doped porous indium phosphide

An indium-phosphide InP sample subjected to the pore-generation procedure and then doped with S atoms is studied by the methods of X-ray diffraction analysis (XRD) and small-angle X-ray scattering (SAXS) (with Cu$K_{\alpha1}$-radiation). The XRD data demonstrate that the sample consists of (coherent) aligned homogeneous components. A point detector is used to obtain, in the anomalous transmission mode by Borrmann, a set of SAXS curves at sample positions varied by azimuthal rotations. The SAXS data are used to simulate a 2D SAXS pattern for the sample under study, which makes it possible to determine the long-distance translation symmetry and, consequently, the presence of a superstructure. The interplanar distances in the superstructure in the directions (110) and (1$\bar1$0) of the InP lattice are found to be $\sim$260 and 450 nm, respectively. The symmetry group of the superstructure is determined as $C_{2v}$ in the (001) plane of the sample lattice.