Transmission Electron Microscopic Observation of AlN/α-Al₂O₃ Heteroepitaxial Interface with Initial-Nitriding AlN Layer

Abstract

The AlN/α-Al 2 O 3 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-Al 2 O 3 substrate surface to a nanometer-thick AlN single-crystal buffer layer in NH 3 ambient just before AlN deposition. The (1\bar210)AlN/(1\bar102)α-Al 2 O 3 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.