Fabrication, Characterization, and Studies of Physical Properties of High-Temperature Superconductor and Iii-V Semiconductor Hybrid System
Abstract
The discovery of new high temperature superconductors (HTSC) above liquid nitrogen temperature has made applications of superconductivity more feasible. The advantage of superconductivity and reduced cryogenic cost is expected to have technological impacts in many fields. This dissertation is devoted to the pursuit of growing high quality HTSC on semiconductor substrates as well as preserving the substrate quality for making practical device structures. An in situ technique in a special designed deposition system was developed for the formation of HTSC YBaCuO thin films. Even with the in situ growth of YBaCuO at a relatively low temperature 635^circC, serious interactions occur between the YBaCuO film and the directly deposited GaAs substrate. We first found the suitability of MgO as buffer layers for YBaCuO growth on GaAs, and developed a deposition scheme to form epitaxial MgO on GaAs. The quality of the high T_{rm c} super-semi hybrid structure was greatly improved by the use of an epitaxial MgO buffer layer to serve as a good template for YBaCuO and to prevent the interactions at the interface. Post-growth assessment on GaAs substrates was performed to confirm the effectiveness of the MgO buffer layer in preserving the substrate quality. The success of MgO buffer layers enabled us to fabricate a suitable high T_{rm c} super -semi structure to study the magnetization and flux creep of YBaCuO probed by the adjacent semiconductors. A simple model was developed to show the sensitivity and resolution that can be achieved in the super-semi structure. The penetration depth of YBaCuO can also be extracted from that model using the results of flux-trapping measurements.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1994
- Bibcode:
- 1994PhDT.......114T
- Keywords:
-
- GROUP III-V;
- YTTRIUM BARIUM COPPER OXIDE;
- Engineering: Materials Science; Physics: Condensed Matter