SURFACE-RESISTANCE OF LARGE-AREA TL2BA2CACU2O8 THIN-FILMS AT MICROWAVE AND MILLIMETER-WAVE FREQUENCIES MEASURED BY 3 NONCAVITY TECHNIQUES

The surface resistance R(s) of Tl2Ba2CaCu2O8 films fabricated on LaAlO 3 wafers up to 3 inches (7.6 cm) in diameter through a post-deposition anneal process was measured over the frequency range 5.55-94.1 GHz by the following techniques: 5.55 and 27.5 GHz high-temperature supercon ductor (HTS) sapphire resonators, 10 GHz parallel plate resonator, and 94.1 GHz scanning confocal resonator. R(s) was found to exhibit a qua dratic dependence on frequency f at 77 K: R(s) is-proportional-to f2.0 +/-0.1. The highest-quality films yield R(s) = 145 +/- 15 muOMEGA at 1 0 GHz and 77 K. Scanning confocal resonator mapping of R(s) across a 2 -inch (5.1 cm) diameter wafer yielded a base value for R(s) of 16 +/- 1 mOMEGA at 77 K and 94.1 GHz (equivalent to 180 +/- 10 muOMEGA at 10 GHz) and good uniformity in R(s) across the wafer. HTS-sapphire resona tor measurements of R(s) for fifteen 1.2 cm square parts cut from a 3- inch diameter wafer yielded R(s) values scaled to 10 GHz of 196 +/- 10 muOMEGA at 80 K. Similar values were measured for Tl2Ba2CaCu2O8 films prepared on both sides of a 2-inch diameter wafer. R(s) values at 10 GHz and 80 K of 147-214 muOMEGA were maintained over the course of 40 independent and successive deposition runs and corresponding anneals u nder nominally identical film fabrication conditions. Surface resistan ce at 5.55 GHz remained below 80 muOMEGA for maximum rf magnetic field s up to 85 Oe at 4.2 K and 7 Oe at 80 K, respectively. Results are com pared with predictions of the two-fluid model. The relative advantages and disadvantages of the different techniques for measuring surface r esistance are discussed.