Fabrication and Characterization of SQUIDs With Nb/NbxSi1- x/Nb Junctions

Superconducting quantum interference devices (SQUIDs) with 3 μm × 3 μm or 4 μm × 4 μm self-shunted Nb/Nb
_x
Si
_1-x
/Nb Josephson junctions are designed and fabricated. By adjusting the Nb content and thickness of the Nb
_x
Si
_1-x
barrier, the parameters of the SQUIDs can be easily tuned. The optimal parameters for the barrier are found to be a thickness of around 15 nm and 7% Nb content. The I-V curve, V-Φ curve, and noise spectrum are measured for the SQUID. The high frequency noise for the SQUID is only about several hundred nΦ
₀
/√Hz. Another advantage for these devices is found, that it is not sensitive to the static electricity.