  Superconductor films on semiconductor substrates draw much attention recently
since the derived superconductor-based electronics have been shown promising
for future data process and storage technologies. By growing atomically uniform
single-crystal epitaxial Pb films of several nanometers thick on Si wafers to
form a sharp superconductor-semiconductor heterojunction, we have obtained an
unusual giant magnetoresistance effect when the Pb film is superconducting. In
addition to the great fundamental interest of this effect, the simple structure
and compatibility and scalability with current Si-based semiconductor
technology offer a great opportunity for integrating superconducting circuits
and detectors in a single chip.
