Growth of atomically flat-surface aluminum nitride epitaxial film by metalorganic chemical vapor deposition

A high c-axis-oriented and atomically flat-surface aluminum nitride (AlN) film has been successfully deposited on a (0001)sapphire substrate by metalorganic chemical vapor deposition. We evaluated the dependences of surface roughness, tilted mosaicity and twisted mosaicity on the conditions of AlN deposition. It was found that the atomically flat-surface AlN film was deposited under the diffusion-limited area with suppression of vapor phase reaction at a substrate temperature of 1200°C and a V/III ratio of 800. It was also recognized that surface roughness was controlled by gas flow velocity, which is determined by both gas flow rate and pressure in reactor. Mean surface roughness (R_a) of the deposited AlN films was approximately 1 Å. The full width at half maximum of X-ray rocking curve for (0002) and (101̄2)AlN were approximately 100 and 2300 arcsec, respectively.