Fabrication and Structure of Co/Cu Artificial Superlattices

Highly oriented Co/Cu artificial superlattices were prepared using a UHV deposition technique. RHEED patterns were observed in situ during the fabrication process. The Co/Cu superlattices were grown at a relatively low temperature (50°C) onto Si (111) single-crystal substrates with Ag (111) buffer layers. The thickness of each layer was varied between 8 and 33 Å. From the RHEED patterns it was confirmed that the surfaces of both the Co and the Cu layers were atomically flat. X-ray measurements showed that all the samples had a compositionally modulated structure, and both Co and Cu layers had the fcc structure with coherent interfaces when Co layers were thinner than 16 Å. The Co/Cu superlattices were essentially single crystals containing stacking faults and twinning faults. The Co-Cu system is considered to be one of the most suitable for obtaining superlattices with sharp interfaces.