Josephson current in Nb/InAs/Nb highly transmissive ballistic junctions

Highly transmissive ballistic junctions are demonstrated between two superconducting Nb electrodes and the two-dimensional electron gas formed at an InAs/AISb heterojunction. A reproducible fabrication protocol is presented yielding good critical supercurrent values. Current-voltage characteristics were measured down to 0.4 K and the observed supercurrent behavior was analyzed within a ballistic model in the clean limit. This investigation allows us to demonstrate an intrinsic interface transmissivity exceeding 86%.