A p(2 x 2) surface reconstruction was observed at 800 to 900C for SrTiO3 (100), the temperature range used in the oxygen annealing of Y, Ba, Cu layers on SrTiO3 (100) substrates in the synthesis of high Tc superconducting thin films. As observed by Auger electron spectroscopy, high-temperature annealing causes calcium to segregate to the surface. Initially, at a Ca content of 3% upon a SrO-terminated SrTiO3 (100) surface, the Ca atom was incorporated in a superstructure, which was attributed to multiple scattering across the two topmost interfaces. When the surface Ca content was below 1% the p(2 x 2) surface reconstruction was induced. The p(2 x 2) surface reconstruction disappeared when the calcium content was removed.

Impurity-Induced 900C (2 x 2) Surface Reconstruction of SrTiO3(100). J.E.T.Andersen, P.J.Møller: Applied Physics Letters, 1990, 56[19], 1847