STRUCTURE AND DEFECTS OF AN ORDERED ALUMINA FILM ON NIAL(110)

Via oxidation a well ordered Al2O3 film may be grown on an ordered NiA l(110) surface. Its structure has been studied with SPA-LEED (spot-pro file analysis) as well as with scanning tunneling microscopy (STM). Th e oxide overlayer grows strictly two-dimensional with a thickness of c lose to 5 Angstrom. Double diffraction spots have been observed but th ey are very weak, thus not excluding the existence of an interfacial l ayer between NiAl(110) and the oxide film. STM provides preliminary ev idence for such a film and presents first clues to what the structure of the interface may be. The defect structure of the Al2O3 film has be en investigated. In addition to boundaries between two rotational doma ins constituting the Al2O3 film, we also identify anti-phase domain bo undaries through both the SPA-LEED as well as the STM measurements.