AlN epitaxial growth on atomically flat initially nitrided alpha-Al2O3 wafer

The (1 (1) over bar 02) alpha-Al2O3 surface and the initial nitriding AlN layer are investigated using the atomic-force microscope. The initial nitriding method is to convert the (1 (1) over bar 02) alpha-Al2O3 surface to a nanometer-thick AlN single-crystal buffer layer. The epitaxial AlN film is deposited by metalorganic chemical vapor deposition with and without the initial nitriding. Atomic step structure is found to be formed after the H-2 annealing. The atomic step structure is maintained during the initial nitriding time up to 5 min. Smooth AIN epitaxial films have been successfully deposited on the 2 inch diameter (1 (1) over bar 02) alpha-Al2O3 wafer without any inverse-twin throughout the wafer by keeping the atomic step structure of the initial nitriding buffer layer.