Characterization of the low temperature behavior of thin Titanium/Titanium Nitride multilayer films

Titanium and titanium nitride layers were alternately sputtered on a high resistivity silicon wafer to obtain a multilayer film structure, for a total thickness ranging between 34 and 180 nm. The electrical resistance of the Ti/TiN film was characterized from room temperature down to the superconducting transition. Both the resistivity just above the transition and the critical temperature were investigated as a function of the total film thickness and the single TiN layer thickness, respectively. The obtained resistivity range is 67-312 μΩ cm. Exploiting the proximity effect, we were able to tune the critical temperature in the 0.29-4.5 K range. A comparison between experimental data and theoretical models is proposed in order to facilitate the a priori design of superconducting detectors.