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 init ial nitriding method is to convert the (1 (1) over bar 02) alpha-Al2O3 surface to a nanometer-thick AlN single-crystal buffer layer. The epi taxial AlN film is deposited by metalorganic chemical vapor deposition with and without the initial nitriding. Atomic step structure is foun d to be formed after the H-2 annealing. The atomic step structure is m aintained during the initial nitriding time up to 5 min. Smooth AIN ep itaxial films have been successfully deposited on the 2 inch diameter (1 (1) over bar 02) alpha-Al2O3 wafer without any inverse-twin through out the wafer by keeping the atomic step structure of the initial nitr iding buffer layer.