Abstract: X-ray wave diffraction devices are constructed using atomic layer epetaxy. A crystalline substrate is prepared with one or more surface areas on which multiple pairs of layers of material are to be deposited. These layers are then formed by atomic layer epetaxy on the surface areas of the substrate, one on top of another, with the material of each layer of each pair being selected to have a different index of refraction from that of the material of the other layer of each pair. The layers are formed so that the thickness of each layer of a pair is substantially the same as that of the corresponding layer of every other pair and so that x-ray waves impinging on the layers may be reflected therefrom. Layer pairs having a thickness of about 20 angstroms or less are formed on the substrate.