Surface structures of MgO(100) and SrTiO3(100) as revealed by atomic force microscopy

We have investigated surface structures of MgO(100) and SrTiO3(100) by atomic force microscopy. Atomically flat terraces separated by monatomic height steps could be obtained on the freshly cleaved MgO(100) surfaces. We have observed an atomic structure indicating a bulk terminated (1 X 1) structure on the terraces. We have found that nanocrystals, which might be an indication of the surface roughening, were formed on the MgO(100) surfaces after O-2 annealing. For SrTiO3(100), we have clarified that the step-terrace structure was obtained by O-2 annealing at 1100 K. Annealing at 1300 K, however, resulted in morphology changes from flat to rough and non-faceted surfaces.