X-ray perfection study of Verneuil-grown SrTiO 3 crystals

Abstract

Dislocations, subgrain textures and other long-range strains in Verneuil-grown SrTiO 3 crystals, used widely as a substrate for growing high- T c superconducting thin films, have been studied by reflection and transmission X-ray topography to characterize the crystal in regard to structural perfection. It was found that dislocations are nearly aligned along the 〈1 0 0〉 directions and most of them are of pure edge type, presumably as a property of annealed crystals with simple cubic lattice. This entire dislocation alignment causes a strong long-range distortion about the [0 0 1] axis in anisotropic (1 1 0)-oriented crystal plates. Burgers vectors both of 〈1 0 0〉 and 〈1 1 0〉 types were observed. It was also found that the surfaces of some samples were finished highly strain-free as well as optically flat by the mechanochemical polishing.