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

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 ΔT_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.