The microstructures and interfaces of high-quality superlattices were investigated by means of high-resolution transmission electron microscopy. This revealed that the superlattices had atomically sharp interfaces between the oxide layers; with no interdiffusion. However, an intermediate layer (about 1nm in thickness) with many defects was observed at the film/substrate interface and was attributed to surface steps and dislocations at SrTiO3 substrate surfaces. On the other hand, the film did not exhibit extended defects which extended beyond several unit cells. This was achieved by the formation of c/3 or 2c/3 step stacking faults at the substrate surface steps.

Y.J.Li, G.C.Xiong, G.J.Lian, J.Li, Z.Z.Gan: Materials Science Forum, 1995, 189-190, 381-6