Mo/Au Bilayer Superconducting Transition Edge Sensor Tuning With Surface Modification Structures

We have conducted an experimental study tuning the critical temperature, transition width, normal resistance, and critical current of Mo/Au bilayer transition edge sensors (TES) using Nb stripes on the TES surface. The Nb stripes modify the TES parameters through the lateral proximity effect. We summarize the dependence of the shift in transition temperature and the broadening of the transition width on the separation length between the Nb stripes and leads. We calculate the Ginzburg-Landau coherence length of the TES in two methods. One takes advantage of the dependence of the TES normal resistance on the number of the TES and Nb contacts. Another utilizes the temperature dependence of the TES critical current. The two methods are in good agreement with a coherence length ξ₀ ≈ 0.4 μm.