Degradation in molybdenum thin films and Mo/AuPd bilayers and its reduction by sidewall passivation

Molybdenum is a common material for superconducting thin films used, for example, in transition edge sensors as Mo/metal bilayers. For such applications long term stability of the superconducting parameters is essential, especially the critical temperature and the transition width. Our analysis of the effect of film oxidation on these parameters for Mo/AuPd bilayers shows that even slight oxidation will have a significant effect. A direct comparison shows the potential of sidewall passivation to reduce the degradation and stabilize these parameters.