A HIGH TRANSITION TEMPERATURE SUPERCONDUCTING INTEGRATED CIRCUIT (DC SQUID, INPUT COIL, PLANAR COUPLING, MICROBRIDGE) | Posted on:1986-03-28 | Degree:Ph.D | Type:Thesis | University:Stanford University | Candidate:DIIORIO, MARK STEVEN | Full Text:PDF | GTID:2472390017459855 | Subject:Physics | Abstract/Summary: | | This thesis describes the design and fabrication of the first superconducting integrated circuit capable of operating at over 10 K. The primary component of the circuit is a dc SQUID (Superconducting QUantum Interference Device) which is extremely sensitive to magnetic fields. The dc SQUID consists of two superconductor-normal metal-superconductor (SNS) Josephson microbridges which are fabricated using a novel step-edge process which permits the use of high transition temperature superconductors. By utilizing electron-beam lithography in conjunction with ion-beam etching, very small microbridges can be produced. Such microbridges lead to high performance dc SQUIDs with products of the critical current and normal resistance reaching 1 mV at 4.2 K. These SQUIDs have been extensively characterized, and exhibit excellent electrical characteristics over a wide temperature range.; In order to couple electrical signals into the SQUID in a practical fashion, a planar input coil was integrated for efficient coupling. A process was developed to incorporate the technologically important high transition temperature superconducting materials, Nb-Sn and Nb-Ge, using integrated circuit techniques. The primary obstacles were presented by the metallurgical idiosyncrasies of the various materials, such as the need to deposit the superconductors at elevated temperatures, 800-900(DEGREES)C, in order to achieve a high transition temperature. Consequently, the fabrication process had to allow for these elevated deposition temperatures.; The completed circuits operated successfully over a wide temperature range, from 4.2 K to 14 K. Limitations were encountered in the form of an excess inductance. The origins of such an inductance have important and wide-ranging ramifications for superconducting devices employing the high transition temperature materials. | Keywords/Search Tags: | High transition temperature, Superconducting, Integrated circuit, Dc SQUID | | Related items |
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