Misfit dislocations in the epitaxial (111) Cu₂O/(111) Cu system

Abstract

Direct TEM studies on the epitaxial growth of (111) Cu₂O on (111) Cu have been made. Flat monocrystalline (111) Cu substrates, approximately 1300 Å thick, were formed and annealed in-situ in a U.H.V.-RHEED system on (111) NaCl/mica bilayers using previously published techniques. These Cu films were oxidized at 350°C using partial oxygen pressures ranging from 1 × 10⁻⁶ to 5 × 10⁻⁵ torr and for times of 1 to 5 min. Electron microscopy shows that a laminar Cu₂O growth mode occurs for the shorter exposures along with the previously observed oxide pyramids. The coincidence lattice misfit strain between the laminar overgrowth and the Cu substrate is accommodated partially by edge dislocations lying along the three <110> directions in the (111) interface plane and by elastic strain in the bilayer. The Burgers vectors of these misfit dislocations are found to be α[110], α[101], and α[011], where a is the lattice constant of the Cu₂O unit cell.