Fabrication and characterization of Al-Mn superconducting films for applications in TES bolometers*

Abstract

Superconducting transition edge sensor (TES) bolometers require superconducting films to have controllable transition temperatures T c in different practical applications. The value of T c strongly affects thermal conductivity and thermal noise performance of TES detectors. Al films doped with Mn (Al–Mn) of different concentrations can accomplish tunable T c . A magnetron sputtering machine is used to deposit the Al–Mn films in this study. Fabrication parameters including sputtering pressure and annealing process are studied and their influences on T c and superconducting transition width Δ T c are optimized. The Al–Mn films with Δ T c below 1.0 mK for T c in a range of 520 mK–580 mK are successfully fabricated.