Abstract
The AlN/α-Al2O3 heteroepitaxial interface is investigated using a transmission electron microscope. The epitaxial AlN film is deposited by metalorganic chemical vapor deposition with and without initial nitriding. The initial nitriding method is to convert the α-Al2O3 substrate surface to a nanometer-thick AlN single-crystal buffer layer in NH3 ambient just before AlN deposition. The (1\bar210)AlN/(1\bar102)α-Al2O3 interface with initial nitriding is found to be atomically flat, and no dislocation inside the postdeposited AlN is observed. We have confirmed that initial nitriding is excellent in improving the crystal quality of the AlN epitaxial layer.