Charge transport in two-dimensional electron gas/insulator/superconductor junctions with Rashba spin-orbit coupling

We have studied the tunneling conductance in two-dimensional electron gas/insulator/superconductor junctions in the presence of Rashba spin-orbit coupling (RSOC). It is found that for low insulating barriers the tunneling conductance is suppressed by the RSOC while for high insulating barriers it is almost independent of the RSOC. We also find reentrant behavior of the conductance at zero voltage as a function of the RSOC for intermediate insulating barrier strengths. The results are essentially different from those predicted in ferromagnet/superconductor junctions. The present derivation of the conductance is applicable to arbitrary velocity operators with off-diagonal components.