Determination of the Parameters of Tunneling Barriers of Superconducting Tunnel Structures for Submillimeter Receivers

Abstract

Abstract—The parameters of the tunneling barrier of Nb/Al–AlO_x/Nb Josephson junctions were estimated in a wide range of current densities using the Simmons method. It is shown that with an increase in resistivity R_nS from 60 to 2100 Ω μm² (a reduction in the density of the tunneling current of junction J from 3.5 to 0.1 kA/cm²), the height of the tunneling barrier increases from 0.85 to 1.18 eV and its width increases from 10.7 to 13.3 Å. The experimentally observed linear dependence of the tunneling barrier parameters on R_nS made it possible to estimate the capacitance of junctions in the range of R_nS 10–30 Ω μm² required to create low-noise submillimeter-range receivers.