Chapter 5 Heteroepitaxial metal growth: the effects of strain

Abstract

This chapter discusses heteroepitaxial metal growth. Epitaxial thin films have attracted considerable attention in recent years in the search for new materials. The growth of crystalline films on a crystalline substrate (epitaxy) offers the opportunity to create metastable structures with novel physical and chemical properties. A topical example is the heteroepitaxial growth of Fe on the Cu (100) surface in which the lattice misfit forces Fe films below a critical thickness to adopt the face-centered-cubic (fcc) structure of the Cu substrate, although under normal conditions Fe has a body-centered-cubic (bcc) structure. The fcc Fe-films are particularly interesting with respect to their magnetic properties. Because smooth epilayers with atomically abrupt interfaces are desired for most applications, the understanding and control of strain relief, and its influence on the film morphology are of primary importance. Dislocations can also act as preferred nucleation sites that can be understood in terms of localized strain, which either facilitates exchange or locally increases migration barriers or binding energies.