DECAY LENGTHS FOR DIFFUSIVE TRANSPORT ACTIVATED BY ANDREEV REFLECTIONS IN AL N-GAAS/AL SUPERCONDUCTOR-SEMICONDUCTOR-SUPERCONDUCTOR JUNCTIONS/

In a highly doped GaAs semiconductor with superconducting contacts of Al, clear conductance peaks are observed at zero voltage bias and at V = +/-2 Delta/e, +/-Delta/e. The subharmonic energy gap structure orig inates from Andreev scattering with diffusive, but energy conserving, transport in the GaAs. The zero bias excess conductance is due to phas e-coherent transport. Both effects are suppressed when the distance be tween the superconducting electrodes exceeds the inelastic diffusion l ength in the GaAs normal channel.