While investigating the first stages in the growth of pulsed-laser deposited YBa2Cu3O7–δ on single terminated (100)SrTiO3 substrates, a study was made of the formation of these dislocations. It was found that the formation of linear defects occurred above a critical layer thickness where a coherent growth transition took place. Coherent islands were formed, surrounded by highly strained trenches. These trenches facilitated the formation of dislocation half-loops. Such half-loops relieved the misfit strain and formed misfit and threading dislocations. The number of threading dislocations therefore depended upon the island density. This explained the short-range lateral order of the threading dislocations and their decreasing density at high substrate temperatures.

Strong Pinning Linear Defects Formed at the Coherent Growth Transition of Pulsed Laser-Deposited YBa2Cu3O7–δ Films. B.Dam, J.M.Huijbregtse, J.H.Rector: Physical Review B, 2002, 65[6], 064528 (8pp)