APPARATUS FOR PRODUCING ULTRACLEAN BICRYSTALS BY THE MOLECULAR-BEAM EPITAXY GROWTH AND ULTRAHIGH-VACUUM BONDING OF THIN-FILMS

An apparatus has been designed and constructed which is capable of growing single-crystal thin films and then bonding them together face-to-face to produce bicrystals under ultrahigh vacuum (UHV) conditions. The films are grown in molecular beam epitaxy (MBE) system capable of growing well-characterized single-crystal thin films of metals, semiconductors, and high T(c) superconductors. It has the unique capability to perform multiple processing steps on a substrate within a continuous 10(-11) Torr (base pressure) UHV environment. The system is computer controlled and whole-growth sequence parameters can be readily programmed. This design allows the manufacture of films of new structural materials and the ability to change layer type or composition within atomic monolayer dimensions. The MBE chamber is connected to a surface analytical and bonding chamber into which the grown films can be transferred, characterized, and bonded together at controlled misorientations. The bonding operation is carried out in a 10(-10) Torr UHV environment, assuring cleanliness of interfaces. The system has the potential to produce a wide variety of new homophase and heterophase bicrystals containing interfaces in a form suitable for further study.