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Microstructure of YBa2Cu3O7-δ/Ag Bilayers Grown In Situ on Step-Edge SrTiO3 Substrates

Published online by Cambridge University Press:  15 February 2011

Z. H. Gong ,
J. K. Grepstad ,
S. Andersen  and
A. Bardal
Z. H. Gong
Affiliation:
Dept. of Physical Electronics, The Norwegian Institute of Technology, N-7034 Trondheim, Norway
J. K. Grepstad
Affiliation:
Dept. of Physical Electronics, The Norwegian Institute of Technology, N-7034 Trondheim, Norway
S. Andersen
Affiliation:
SINTEF Applied Physics, N-7034 Trondheim, Norway
A. Bardal
Affiliation:
SINTEF Applied Physics, N-7034 Trondheim, Norway
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Abstract

The microstructure of YBa2Cu3O7-δ(YBCO)/Ag bilayers sputter deposited in situ on step-edge SrTiO3 (STO) substrates, was carefully examined by transmission electron microscopy (TEM). Considerable variation in the YBCO film growth morphology is found near steps, including film protrusions beyond the step edges and film growth on slopes. Lattice images recorded near steps unveil a high density of crystalline defects in the film. An increased density of defects is also found near the substrate interface for film grown on etched STO surface. However, these defects are confined to the interface region and do not propagate beyond the scale of the STO surface roughness. Comparison of TEM lattice images of YBCO(100)/Ag and YBCO(001)/Ag junctions from the same specimen unveils a distinct difference in the interfacial microstructure of those two junctions. Whereas the former exhibits a sharp crystalline interface, the latter typically features a thin ( ∼ 20 Å ) interfacial layer of amorphous material. The YBCO film morphology and the high density of defects in the step edge region uncovered in this study suggest that manufacture of reproducible and uniform YBCO/Ag (Au)/YBCO (SNS) Josephson junctions using the step-edge technique, will prove a difficult task.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 401: Symposium G – Epitaxial Oxide Thin Films II , 1995 , 345
Copyright
Copyright © Materials Research Society 1996

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