High-temperature superconductive devices on sapphire

The low-loss and uniform dielectric properties of sapphire make it attractive for high-performance microwave devices using high-temperature superconductors. YBa/sub 2/Cu/sub 3/O/sub 7/spl minus//spl delta// films have been deposited on oxide-buffered 5-cm-diameter wafers and demonstrated a surface resistance of 0.5 m/spl Omega/ at 10 GHz and 77 K. Long (9-ns) stripline delay lines have for the first time been produced on these substrates and have a measured insertion loss of 1.5 dB at 6 GHz and 77 K. Design techniques appropriate for the dielectric anisotropy of sapphire are discussed.<
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