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 gro wing single-crystal thin films and then bonding them together face-to- face to produce bicrystals under ultrahigh vacuum (UHV) conditions. Th e films are grown in molecular beam epitaxy (MBE) system capable of gr owing well-characterized single-crystal thin films of metals, semicond uctors, 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 c ontrolled and whole-growth sequence parameters can be readily programm ed. This design allows the manufacture of films of new structural mate rials and the ability to change layer type or composition within atomi c monolayer dimensions. The MBE chamber is connected to a surface anal ytical and bonding chamber into which the grown films can be transferr ed, 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 con taining interfaces in a form suitable for further study.