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.