Anewmechanismformisfitdislocationgeneration.PDFVIP

Journal of Crystal Growth 234 (2002) 603–609 A new mechanism for misfit dislocation generation: superdislocations associated with Ruddlesden–Popper planar defects a, a a b b J.S. Wu *, C.L. Jia , K. Urban , J.H. Hao , X.X. Xi a Institut fur Festkorperforschung, Forschungszentrum Julich GmbH, D-52425 Julich, Germany . . . . b Department of Physics, The Pennsylvania State University, University Park, PN 16802, USA Received 4 September 2001; accepted 8 September 2001 Communicated by R. Kern Abstract We have investigated by high-resolution transmission electron microscopy SrTiO3/SrRuO3 bilayer films epitaxially grown on LaAlO substrate. At the SrRuO /LaAlO interface we frequently observe dissociated superdislocations in 3 3 3 connection with Ruddlesden–Popper-type planar defects. These superdislocations can contribute to misfit relaxation equivalent to a perfect misfit dislocation with Burgers vector a /1 1 0S. The formation and the geometry of this defect arrangement is discussed in detail. The Sr-rich Ruddlesden–Popper-defect can be introduced by composition fluctuations durin gfilm deposition. It can be concluded that it can act as a source for the generation of misfit dislocations. r 2002 Elsevier Science B.V. All rights reserved. PACS: 68.55.Ac; 68.37.Lp; 61.72.Ff Keywords: A1. High resolution electron microscopy (HRTEM); A1. Interface structure; A1.