YBCO wafer qualification by surface resistance measurements combined with performance studies of microstrip resonators

High quality double-sided YBCO wafers with ceria buffered sapphire substrat es are analysed for the lateral homogeneity and field dependence of the sur face resistance (R-S) using an open resonator at 145 GHz and a dielectric r esonator at 8.5 GHz. In a following step, a set of linear microstrip resona tors are patterned on these wafers and are analysed for their high frequenc y performance at 4 GHz. The results reveal surface resistance analysis of Y BCO wafers as a reliable basis for materials qualification, At low power le vels the high Q-factors of the microstrip resonators (about 30 000) are con sistent with the measured R-S-values at the considerably higher frequencies , Further the power handling capabilities of the resonators agree with the measured field dependence of R-S. Surface resistance mappings at 145 GHz ef fectively indicates critical film areas for non-optimum microstrip resonato r performance. (C) 2001 Elsevier Science B.V. All rights reserved.