Semiconductor-coupled Josephson junctions

Superconductor-semiconductor-superconductor junctions have been studied using 50-nm-thick silicon membranes sandwiched between niobium electrodes. The normal state resistance is determined by barriers at the interfaces. The supercurrent is well described by the Kupriyanov-Lukichev theory for the proximity effect in SINIS (superconductor-insulator-normal metal-insulator-superconductor) structures, whereas the voltage-carrying state is understood as resulting from a nonthermal distribution of electrons in the semiconductor. The details of the distribution depend on elastic and Andreev scattering at the interfaces. By analogy to semiconductor heterostructures, the authors propose that these structures be called superconducting quantum wells, a concept which is applicable to other double-barrier tunnel devices as well.<>