MICROWAVE DEVICES USING YBA2CU3O7-DELTA FILMS MADE BY PULSED LASER DEPOSITION

High-quality oriented thin films of YBa2Cu3O7-delta having transition temperatures > 88 K and critical current densities (at 77 K, zero magnetic field) > 10(6) A/cm2 have been made by pulsed laser deposition on <100> MgO and LaAlO3 substrates. The microwave surface resistance (R(s)) has been measured between 20 K and 120 K at 36 GHz by a copper cavity end-wall-replacement technique. R(S) measurements show consistently sharp transitions having high critical temperature onsets with low residual surface resistances (< 10 m-OMEGA at 36 GHz and 77 K). Microwave devices fabricated from films on MgO have included an X-Band modified 5-pole Chebyschev filter having an insertion loss of approximately .8 dB at 77 K. Irradiation of unpatterned films on LaAlO3 with 2 MeV H+ ions at a fluence increment of 10(16)/cm2 resulted in only a small shift (approximately 2 K) in the 36 GHz microwave transition temperature. No accompanying degradation in the residual surface resistance was observed within the sensitivity of our measurement.