Electronic structure and bonding at the Al-terminated Al(111)/α-Al₂O₃(0001) interface: A first principles study

We have performed ab initio calculations to determine the bonding character of the Al-terminated Al(111)/α-Al₂O₃(0001) interface. By using an optimized model in which all atomic coordinates were relaxed to their minimum energy positions, we have determined that Al-O bonds constitute the primary interfacial bonding interaction. Our electron localization, Mayer bond order, and Mulliken population analyses reveal that these bonds are very similar to the cation-anion bonds found in the bulk oxide, and are therefore mainly ionic, with a smaller amount of covalent character. However, there is also evidence of metal-cation bonding across the interface, a result which could be significant to understanding bonding at interfaces with other corundum-like oxides.