Twinning and precipitates in YBa2Cu3O7–δ thin films grown onto vicinal SrTiO3 (100) substrates were investigated. The direction of the in-plane cut of the substrate was chosen to be close to [010] or [110]. In the first case, the surface steps created an anisotropic surface morphology, the YBa2Cu3O7 film grew with the c-axis perpendicular to the SrTiO3 (100) crystal lattice plane and twinning in one in-plane direction could be suppressed. In the second case, the substrate surface was dominated by kinks in the steps, the YBa2Cu3O7 film grew with the c-axis perpendicular to the surface geometrical plane and the film was unidirectionally twinned. Films deposited onto substrates cut along [110] were rather smooth, while deep holes were observed in films grown onto substrates vicinally cut along [010]. It was proved, by cross-sectional transmission electron microscopy, that these holes originated on Y2O3, CuO and Y2O3-CuO precipitates. No direct correlation was found between precipitate formation and microscopic substrate/film features.

Effect of Substrate Vicinality on the Formation of Precipitates and Twins in YBa2Cu3O7– δ Thin Films. R.I.Chakalova, T.J.Jackson, G.Passerieux, I.P.Jones, P.Mikheenko, C.M.Muirhead, C.N.W.Darlington: Physical Review B, 2004, 70[21], 214504 (6pp)