Homoepitaxialn‐type InAs‐coupled superconducting junctions are investigated. Then‐type channel layer on ap‐type substrate has nearly the same mobility as bulk crystal and the layer can be isolated electrically from the substrate by the built‐in potential at thep‐ninterface. As a result, the critical current‐normal resistance (ICRN) product of the homoepitaxialn‐type InAs‐coupled junction is at least 30 times better than those of the bulkn‐type ones. The coherence length xgr;Nis calculated using the experimentally obtained carrier concentration, mobility, and effective mass. Temperature dependence ofICagrees with calculations based on the proximity effect theory which can be applied to the intermediate regime between the clean and dirty limits.
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