Superlattices were discovered early in 1925 by Johansson and Linde after the studies on gold - copper and palladium -copper systems through their special X-ray diffraction patterns. Further experimental observations and theoretical modifications on the field were done by Bradley and Jay, Gorsky, Borelius, Dehlinger and Graf, Bragg and Williams and Bethe. Theories were based on the transition of arrangement of atoms in crystal lattices from disordered state to an ordered state.