PERFORMANCE OF SUPERCONDUCTING MICROWAVE DEVICES PASSIVATED WITH DIELECTRIC MATERIALS

We present a set of experiments which show that three dielectric proce ssing variables in particular affect the performance of superconductin g microwave devices: processing time and temperature, moisture content of the dielectric material, and surface interactions with the high te mperature superconductor (HTS). The changes in microwave performance o f a straight-line microstrip resonator before and after passivation we re quantified by measurements of the loaded and unloaded quality facto rs for each resonator. Dielectric materials of varying moisture conten t were used. The dielectrics were processed at different times and tem peratures. This study shows that the degradation of the microwave devi ces can be minimized by choosing dielectrics which (i) have a low mois ture content, (ii) interact as little as possible with the HTS surface , and (iii) can be rapidly processed at relatively low temperatures. ( C) 1997 American Institute of Physics.