The surface structure of a-plane (112¯0) Al2O3 single crystals with a <101¯0> inclined direction was studied as a function of annealing temperature using atomic force microscopy. The samples had a large increase in step height and terrace width with increasing annealing temperature. For the samples annealed at 1500°C and 1600°C the step edge structure became significantly faceted. The facets consisted of (0001) and (101¯2) planes as a result of these two planes being the ones with the lowest surface energies in Al2O3. In addition, the surface morphology displayed the formation of ridges 0.3nm high and ∼20nm wide at 1600°C which originate from a tendency of the surface to form a (4×1) reconstruction with the sharp step edges acting as reconstruction nucleation sites.

DOI: 10.1016/j.susc.2008.11.015
Version: za2963e q8za6 q8zb2 q8zc2 q8zd0 q8ze5 q8zff q8zg9