300 GHz Operation of Divider Circuits using High-Jc Nb/NbxSi1-x/Nb Josephson Junctions
David I. Olaya, Paul D. Dresselhaus, Samuel P. Benz
We are investigating high-current-density Josephson junctions with Nb(x)Si(1-x)-barriers in single- flux-quantum (SFQ) digital circuits to evaluate their performance at clock frequencies of hundreds of gigahertz. We fabricated static divider SFQ circuits with a- Nb(x)Si(1-x) and a-Si barriers for Jc ranging from 3.5kA/cm^2 to 85 kA/cm^2. For the lower Jc range (3.5 kA/cm^2 to 17 kA/cm^2) we used optical lithography, and for the 85 kA/cm^2 junctions we used e-beam lithography. We measured SFQ circuits with a maximum operating speed of 300 GHz by use of intrinsically shunted junctions having sub-micrometer dimensions and an 85 kA/cm^2 critical current density. These results demonstrate that silicide-barrier junctions have the potential to achieve high-speed SFQ circuits and higher density circuits because the junctions are small and dont require external shunt resistors.
, Dresselhaus, P.
and Benz, S.
300 GHz Operation of Divider Circuits using High-Jc Nb/NbxSi1-x/Nb Josephson Junctions, IEEE Transactions on Applied Superconductivity, [online], https://doi.org/10.1109/TASC.2014.2373317
(Accessed June 29, 2022)