Cryogenic on-wafer microwave characterization of GaAs MESFETs and superconducting coplanar resonance and transmission lines structures

摘要

Abstract: This work directly compares coplanar superconducting transmission lines and single-pole resonators patterned from YBCO to aluminum structures for use in GaAs/YBCO hybrid circuitry. A cryogenic on- wafer station was used to make s-parameter measurements of passive coplanar circuits as well as to characterize the performance of GaAs MESFETs at 80 K. Comparisons were made between measured data and theoretical results for passive YBCO and aluminum structures. The YBCO film was also measured using a parallel plate technique to determine microwave surface resistance to establish a correlation between patterned film and thin film microwave properties. Small-signal models were constructed to accurately predict the operation of 0.25 $mu@m gate length GaAs MESFETs at 80 K under a variety of bias conditions. The cutoff frequency and maximum frequency of operation of the GaAs MESFETs increased by 29% and 13% respectively under a drain-source voltage of 2.0 V (Id $EQ 100% Idss) as the temperature was lowered from 300 K to 80 K. !11