Structural Characterization and Modeling of the Aluminum (111) / Aluminum Oxide (0001) Interface

Abstract We are investigating the structure of the Al (11l)/Al2O3 (0001) interface. Interfaces for this study were produced by epitaxial thin film deposition of aluminum metal onto (0001) oriented single crystal α-Al2O3. The majority of grains within the films are oriented with: (0001)Al2O3 || (lll)Al [10Î0]Al2O3 || [ī10]Al This relationship results in a matching of the close-packed planes and directions of the aluminum metal with those of the oxygen ion sub-lattice in the Al2O3and allows for two variants related by 180° rotations about the aluminum [111] axis. A diffraction pattern showing these two variants is given in Figure 1. Figure 2 shows a HRTEM image of the heteroepitaxial aluminum/Al2O3 interface. The Al2O3 substrate and aluminum overlayer are imaged along the [10Ï0]Al2O3 and [ī10]A1 zones. Over the width of the image, the interface is sharp to within a few atomic layers. The calculated lattice misfit for the Al/Al2O3 system, taken as the difference between the translation vectors of a/3[10ī0]Al2O3 (2.7447 Å) and a/2[ī10]AI (2.8634 Å), is 4.3%. A fundamental issue is the manner in which this misfit is accommodated.