Modern nanotechnology offers new possibilities to create artificial materials such as three‐dimensional (3D) ordered island crystals that might be of interest e.g., for optoelectronic applications. We demonstrate that a completely self‐organized body‐centered tetragonal lattice of SiGe dots can be achieved by reduced pressure chemical vapor deposition (RPCVD). Main subject of this paper is the application of different X‐ray diffraction techniques to study the structural properties of a large ensemble of buried SiGe dots with the target to optimize deposition conditions. This includes specular ω‐2Θ scans to reveal vertical periodicity and strain state, reciprocal space mapping to determine lateral arrangement and symmetry of dots, and in‐plane diffraction to get better inside to the lateral strain distribution close to the surface for further growth simulations.SEM cross‐section images of a SiGe/Si superlattice of imperfect lateral periodic structure of SiGe dots.