Structural characterization of MgO(100) surfaces

The structure, the microtopography and the cleanliness of MgO(100) surfaces have been investigated by a combination of thermal helium scattering, surface decoration and Auger spectroscopy. The microstructure and cleanliness are strongly dependent on the preparation of the surface. MgO surfaces obtained by cleavage under UHV are clean and present a high coefficient for coherent He reflection. MgO surfaces prepared by cleavage in air are contaminated and irreversibly damaged by water vapour. Such surfaces can be cleaned by vacuum annealing but the coefficient of coherent He reflection remains low because of the presence of a high number of defects.