Microwave devices using YBa sub 2 Cu sub 3 O. sub 7 minus delta. films made by pulsed laser deposition

High-quality oriented thin films of YBa{sub 2}Cu{sub 3}O{sub 7} {delta} having transition temperatures {gt}88 K and critical current densities (at 77 K, zero magnetic field) {gt}10{sup 6} A/cm{sup 2} have been made by pulsed laser deposition on {l angle}100{r angle} MgO and LaAlO{sub 3} substrates. The microwave surface resistance (R{sub s}) has been measured between 20 K and 120 K at 36 GHz by a copper cavity end-wall-replacement technique. R{sub s} measurements show consistently sharp transitions having high critical temperature onsets with low residual surface resistances ({lt}10 m{omega} at 36 GHz and 77 K). Microwave devices fabricated from films on MgO have included an X-Band modified 5-pole Chebyshev filter having an insertion loss of {approximately}8 dB at 77 K. Irradiation of unpatterned films on LaAlO{sub 3} with 2 MeV H{sup +} ions at a fluence increment of 10{sup 16} /cm{sup 2} resulted in only a small shift ({approximately}2 K) in the 36 GHz microwave transition temperature.