Electron Diffraction Studies of the Epitaxy of Cu Single Crystals. II. Early Stages of Epitaxy and Interfacial Dislocation Networks

The first stages of epitaxy were investigated with reflection HEED methods for continuous Cu, Cu2O, and Ag films on Cu single-crystal substrates. A new kind of diffraction pattern was obtained from the Cu{111} planes. It is produced by networks of interfacial dislocations. In case of the Cu layers, hexagonal arrangements of screw dislocations are formed in a pure twist boundary. The corresponding Burgers vectors are of the type ½〈110〉. For the Cu2O and Ag films, hexagonal and rhombohedric networks, respectively, of interfacial edge dislocations with Burgers vectors ⅙〈112〉 are probably present. The dislocation densities and modifications in the film lattice constants for the latter two epitaxial systems are in good agreement with values predicted by the theory of interfacial dislocations.