We demonstrate highly transparent vanadium-silicon and aluminium-silicon tunnel junctions, where silicon is doped to remain conducting even in cryogenic temperatures. We discuss using them in a cascaded electronic refrigerator with two or more refrigeration stages, and where different superconducting gaps are needed for different temperatures. The optimization of the whole cascade is a multidimensional problem, but we present an approximative optimization criterion that can be used as a figure of merit for a single stage only.
|Number of pages||5|
|Publication status||Published - 29 Sep 2020|
|MoE publication type||B1 Article in a scientific magazine|