  Epitaxial Al/GaAs/Al structures having controlled thickness of high-quality
GaAs and pristine interfaces have been fabricated using a wafer-bonding
technique. III-V semiconductor/Al structures are grown by molecular beam
epitaxy on III-V semiconductor substrates and bonded to silicon and sapphire.
Selective etching is used to remove the III-V substrate followed by surface
cleaning and superconductor regrowth, resulting in epitaxial Al/GaAs/Al
tri-layers on sapphire or silicon substrates. Structures are characterized with
reflection high energy electron diffraction, atomic force microscopy, X-ray
photoelectron spectroscopy, transmission electron microscopy, and X-ray
diffraction. Applications of these structures to the field of quantum
information processing is discussed.
