High-speed Nb/Nb-Si/Nb Josephson junctions for superconductive digital electronics
David I. Olaya, Burm Baek, Paul Dresselhaus, Samuel Benz
Josephson junctions with cosputtered amorphous Nb-Si barriers are being developed at NIST for use in voltage standard circuits. These junctions have the potential for a wide range of applications beyond voltage standards because their electrical properties can be tuned by controlling both the composition of the barrier and the barrier thickness. If the composition of the barrier is tuned so that the resistivity is close to the metal-insulator transition, the high resistivity allows junctions with a large characteristic voltage and reproducible critical current densities, which should be ideal for high-speed digital superconductive device applications. Because these junctions are intrinsically shunted, there is also no need for external shunt resistors which waste precious chip area. Presently, the AlOx-barrier junctions used in digital superconducting electronics suffer from poor reproducibility, particularly for the high critical-current densities needed for high-speed applications. In this paper, amorphous Nb-Si barrier junctions with characteristic voltages on the order of 1 mV and, consequently, characteristic frequencies on the order of hundreds of GHz, are demonstrated and shown to have reproducible electrical properties.
, Baek, B.
, Dresselhaus, P.
and Benz, S.
High-speed Nb/Nb-Si/Nb Josephson junctions for superconductive digital electronics, IEEE Transactions on Applied Superconductivity, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=33001
(Accessed June 6, 2023)