Resonant transport in Nb/GaAs/AlGaAs heterostructures: Realization of the de Gennes-Saint-James model

Resonant transport is demonstrated in a hybrid superconductor-semiconductor heterostructure junction grown by molecular beam epitaxy on GaAs. This heterostructure realizes the model system introduced by de Gennes and Saint-James in 1963 [P. G. de Gennes and D. Saint-James, Phys. Lett. 4, 151 (1963)]. At low temperatures a single marked resonance peak is shown superimposed to the characteristic Andreevdominated subgap conductance. The observed magnetotransport properties are successfully analyzed within the random matrix theory of quantum transport, and ballistic effects are included by directly solving the Bogoliubov-de Gennes equations.