TEM investigation of interfaces during cuprous island growth

The geometry and epitaxial relationships of interfaces generated during the early-stage oxidation of Cu(1 0 0) surfaces were studied using transmission electron microscopy. The predominant orientation relationship between Cu2O islands and the Cu substrate is cube-on-cube growth, whereby equivalent planes and directions of oxide islands and the metal substrate are matched across the interface, while other epitaxies are occasionally observed. A 6 × 7 coincidence site lattice configuration is observed at the Cu–Cu2O interface for the cube-on-cube epitaxy. The geometry of Cu2O–Cu interfaces is found to depend on the specific epitaxial orientations of Cu2O islands with the Cu substrate: wedge-shaped interfaces are developed for cube-on-cube growth, and edge-on interfaces are formed for other epitaxies. These growth features are attributed to the minimization of the interface energy via the competing factors among the coincidence lattice misfit, misfit dislocations and the metal–oxide interface area.