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Microstructure of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/Ag bilayers grown in situ on step-edge SrTiO{sub 3} substrates

Conference ·
OSTI ID:392179
;  [1]; ;  [2]
  1. Norwegian Inst. of Tech., Trondheim (Norway). Dept. of Physical Electronics
  2. SINTEF Applied Physics, Trondheim (Norway)
The microstructure of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}(YBCO)/Ag bilayers sputter deposited in situ on step-edge SrTiO{sub 3} (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 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 ({approximately}20 {angstrom}) 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.
OSTI ID:
392179
Report Number(s):
CONF-951155--; ISBN 1-55899-304-5
Country of Publication:
United States
Language:
English