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The authors present tunneling results for junctions comprising Mn doped Al films produced by sputter deposition, with Mn concentrations in the range of 0-5000 ppm. Our results for S'/I/S', S'/I/S, and N/I/S junctions demonstrate that Al-Mn alloys can serve both as superconductors with critical temperatures reduced from that of Al and as normal metals. The authors find Al-Mn in this doping range to be otherwise identical to pure Al in terms of its BCS-like tunnel characteristics (for superconductors) and its ability to produce high-quality tunnel barriers. [ABSTRACT FROM AUTHOR]

We demonstrate cooling of the electrons and phonons of a silicon nitride (Si-N) membrane by solid-state refrigerators based on normal metal/insulator/superconductor (NIS) tunnel junctions. We report a temperature reduction of the Si-N membrane from 260 mK to 240 mK, while the electrons in the normal metal of the refrigerator are cooled to 145 mK. We explain the mechanism for cooling an isolated membrane and make quantitative comparisons between experiment and a finite-element thermal model. The model indicates that increasing the thermal conductivity of the cold-fingers, improving the transparency of the tunnel junctions, and reducing the power load through the membrane will make it possible to cool the membrane from 260 mK to below 170 mK. The refrigeration of a membrane makes it possible to integrate other cryogenic devices that require sub-Kelvin temperatures for optimal performance, such as thin-film sensors. We demonstrate this integration by combining NIS refrigerators with an x-ray Transition-Edge-Sensor (TES). [ABSTRACT FROM AUTHOR]