This title appears in the Scientific Report :
1999
Please use the identifier:
http://hdl.handle.net/2128/4448 in citations.
Untersuchung von oxidischen Isolationsmaterialien in heteroepitaktischen Bauelementen auf der Basis von Hochtemperatursupraleitern
Untersuchung von oxidischen Isolationsmaterialien in heteroepitaktischen Bauelementen auf der Basis von Hochtemperatursupraleitern
New Insulating Materials for High-Tc Superconductor Device Applications Most of high-Tc superconductor devices contain at least one interface between YBa2Cu307-x and a non-superconducting material. Due to the short coherence lengt:h of high-Tc compounds the electrica1 properties of these devices are...
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Personal Name(s): | Hojczyk, R. (Corresponding author) |
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Contributing Institute: |
Institut für Festkörperforschung; IFF |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
1999
|
Physical Description: |
III, 157 p. |
Dissertation Note: |
Aachen, Techn. Hochsch., Diss., 1999 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
ohne FE |
Series Title: |
Berichte des Forschungszentrums Jülich
3645 |
Subject (ZB): | |
Link: |
OpenAccess |
Publikationsportal JuSER |
New Insulating Materials for High-Tc Superconductor Device Applications
Most of high-Tc superconductor devices contain at least one interface between YBa2Cu307-x and a
non-superconducting material. Due to the short coherence lengt:h of high-Tc compounds the electrica1
properties of these devices are sensitive to the quality of the interface. In order to avoid a suppression of
the order parameter near the interface the selected non-superconducting material should have a high
degree of structural and chemical... Most of high-T$_{c}$ superconductor devices contain at least one interface between YBa$_{2}$Cu$_{3}$O$_{7-x}$ and a non-superconducting material. Due to the short coherence length of high-T$_{c}$ compounds the electrical properties of these devices are sensitive to the quality of the interface. In order to avoid a suppression of the order parameter near the interface the selected non-superconducting material should have a high degree of structural and chemical compatibility with YBa$_{2}$Cu$_{3}$O$_{7-x}$. The insultaing materials, which were selected from the viewpoint of structural and chemica1 compatibility, are La$_{2}$CuO$_{4+d}$, LaBa$_{2}$Cu$_{2}$NbO$_{8}$, PrBa$_{2}$Cu$_{2}$NbO$_{8}$, GdSr$_{2}$Cu$_{2}$RuO$_{8}$,and BaTbO$_{3}$. Thin films of these materials were prepared with high-pressure sputtering technique in pure oxygen. The structural and electrical properties of these films were investigated. The growth morphology of YBa$_{2}$Cu$_{3}$O$_{7-x}$/BaTbO$_{3}$/YBa$_{2}$Cu$_{3}$O$_{7-x}$ multilayer films were investigated by high-resolution transmission electron microscopy (HRTEM). Depending on the deposition temperature two types of interface between YBa$_{2}$Cu$_{3}$O$_{7-x}$ and BaTbO$_{3}$ were found. At relatively high deposition temperatures the misfit strain is mainly restricted to a narrow (smaller 1 nm) interface layer, whereas at lower temperature a semi coherent interface with well-localized misfit dislocations was observed. Insulating properties of BaTbO$_{3}$ were successfully tested for crossovers in multilayer devices. Furthermore field effect devices and Josephson junctions using BaTbO$_{3}$ as dielectric or barrier material have been investigated. The field effect devices consist of a 6 nm thick YBa$_{2}$Cu$_{3}$O$_{7-x}$ layer as a drain source channel which was covered by a 150 nm thick BaTbO$_{3}$ gate insulator. The temperature dependance of the drain-source resistance was measured for different gate voltages. The critical temperature of the drain-source channel was shifted of about 1-2 K due to the gate voltage. The ramp-type Josephson juntions included chemically as well as ion beam etched ramp-edges. In both cases the normal resistance decreases with decreasing temperature for a barrier thickness of 10 nm. For chemically etched junctions well defined Shapiro steps and a characteristic voltage of about 0,2 mV at 77 K were observed. |