Al2O3 α surface structure characterization by Rheed

The morphology of cu Al2O3 surfaces annealed in vacuum has been investigated by reflection high energy electron diffraction (RHEED). We have studied two kinds of faces: (0001) and ((1) over bar 012). The two faces behave differently. At high temperature the (0001) surface is unstable with only small facets and give evidence for variations of stoichiometry and structure with formation of an Al layer. The ((1) over bar 012) surfaces give large facets and the diffraction patterns are consistent with (2 x 1) surface structure.