High T/sub c/ thin film and device development

Thin films of the high-T/sub c/ superconductor YBa/sub 2/Cu/sub 3/O/sub y/ have been deposited on various substrates by diode and magnetron sputtering using bulk sintered targets. These films have been analyzed by a variety of methods: scanning electron microscopy, X-rays, electron beam microprobe, mass spectroscopy and Raman spectroscopy. The stoichiometries of the films have been measured as a function of the radial position from the center of the sputtered beam at a fixed target-substrate distance. Patterning of the films has been carried out to form planar structures such as strip lines, microbridges and RF SQUIDs (superconducting quantum interference devices). The DC current-voltage characteristics of the microbridges were measured as a function of temperature. RF SQUID behavior has been observed for single-loop devices and their properties established at 4.2 K and higher temperatures. Flux-locked noise spectra with a 1/f noise power response were recorded in the frequency range from 0.01 to approximately=100 Hz. RF SQUID signals have been observed for temperatures up to 55 K.<
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