Strong Nonlinear Response of Superconducting Tunnel Junctions due to Localized Traps

Publisher Website
Google Scholar
Abstract
The responsivity of a single superconducting tunnel junction for photon detection has been determined over a wide range of energy from optical to hard x ray. An unexpected rapid increase of responsivity is found in the ultraviolet regime. We show that the effect is due to the presence of localized traps—regions of locally reduced energy gap containing a number of confined states. The balance equations for nonequilibrium quasiparticles have been generalized to account for the effects of localized traps. Quantitative modeling yields the details of trap density and trapping probability.