By placing several Si delta-doped layers close to the surface of a GaAs molecular beam epitaxy-grown crystal, we achieve a compensation of the Schottky barrier and obtain a good Ohmic contact between an in situ deposited (without breaking the vacuum) Al metallization layer and a highly modulation doped (n(++)) conduction layer embedded below the delta-doped layers in the GaAs crystal. When cooled to below the critical temperature (approximate to 1.2 K) of Al, superconductivity is induced in the conductive layer of the semiconductor. We have studied the current voltage (I-V) characteristics in a planar geometry where the Al has been removed in a thin stripe. We find a manifestation of the superconducting energy gap and a rich fine structure at injection energies both below and above the gap. (C) 1996 American Institute of Physics.
Bibliographical noteCopyright (1996) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
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