STEPS AND THE STRUCTURE OF THE (0001)ALPHA-ALUMINA SURFACE

The initial stages of facet formation on the (0001) a-alumina surface are explored through annealing vicinal single crystals for different l engths of time and characterizing the surface with atomic force micros copy. Faceting of the (0001) surface begins with the formation of 0.2 nm or similar to c/6 high steps (c=1.3 nm). These steps show a prefere nce for existing as pairs; the pairs then bunch together and form face ts which are typically multiples of c in height. In this fashion, sing le facets and faceted domains initially exist together on the same sur face. A faceted terrace-and-step morphology develops as the facet doma ins coalesce with longer annealing times.