Thermal response of Josephson junction arrays on silicon nitride membranes

Abstract

In order to study the vortex dynamics in Josephson junction arrays under temperature perturbations we have build Pb/Cu structures on top of Si3N4 membranes. Membranes with an area of 1 mm2 and with a thickness of 650 nm were fabricated by anisotropic etching of a silicon substrate previously covered with a low stress nitride film. By e-beam lithography and thermal evaporation we defined two similar SNS Josephson arrays one on top of the membrane and another on the bulk substrate. The heat source was provided illuminating the sample space with a conventional LED placed a few millimeters away from the substrate. Using the superconducting transition of both arrays the thermal response of the system has been characterized obtaining a cut-off frequency of 150 Hz and the power efficiency of our setup.