Suppression of Josephson currents in ballistic junctions by an injection current

Control of the critical current in a superconductor/two-dimensional electro n gas Josephson junction by means of an injection current is reported. The control mechanism is explained by a theoretical model, which takes ballisti c transport across the junction and diffusive transport through the semicon ductor wire structure into account. Measurements on a Nb-AlGaSb/InAs-Nb jun ction show that the strong suppression of the critical current can, in prin ciple, be explained by the theoretical model. Deviations are due to the non linear current-voltage characteristics of the superconductor/two-dimensiona l electron gas interface and the two-dimensionality of the supercurrent tra nsport. (C) 1999 Academic Press.