  We observe a maximum in the conductance of Aluminum / n-GaAs junctions at
temperatures 20 mK lower than the superconducting transition temperature. This
is the first observation of a non- monotonic behavior of the conductance near
the superconducting transition in superconducting normal junctions. To
accommodate this effect we calculate the full temperature dependence of the
conductance of these structures, invoking quasiclassical Green's functions in
the diffusive limit. In addition to the well-known low temperature peak at
temperatures on the order of the Thouless energy, we find a maximum near the
critical temperature. This peak has the same origin as the subgap conductance
observed in superconducting-normal junctions at low temperatures. Its
calculated magnitude and position are in good agreement with our experimental
observation.
