MORPHOLOGY AND ORIENTATION OF NANOCRYSTALLINE ALN THIN-FILMS

This paper describes the surface morphology, composition, and structur e of aluminum nitride (AlN) thin films formed by single ion-beam sputt ering of Al. Either pure N2 or a N2 (75%) + H2 (25%) gas mixture was u sed as the feed gas for the ion gun. The films formed from the hydroge n containing feed gas were deposited on substrates either at room temp erature or at 200-degrees-C. The film surface was extremely smooth for films grown under all the deposition conditions: scanning force micro scopy indicated less-than-or-equal-to 1 nm average roughness over a 50 0 x 500 nm2 area. Transmission electron microscopy examination of the films showed that they were highly textured: the c axis of the AlN gra ins is preferentially oriented perpendicular to the film/substrate int erface. The films grown with pure N2 consisted of grains in the order of 100 nm in diameter whereas films formed with a hydrogen containing feed gas had at least an order of magnitude smaller grain size.