  Recent improvements in materials growth and fabrication techniques may
finally allow for superconducting semiconductors to realize their potential.
Here we build on a recent proposal to construct superconducting devices such as
wires, Josephson junctions, and qubits inside and out-of single crystal silicon
or germanium. Using atomistic fabrication techniques such as STM hydrogen
lithography, heavily-doped superconducting regions within a single crystal
could be constructed. We describe the characteristic parameters of basic
superconducting elements---a 1D wire and a tunneling Josephson junction---and
estimate the values for boron-doped silicon. The epitaxial, single-crystal
nature of these devices, along with the extreme flexibility in device design
down to the single-atom scale, may enable lower-noise or new types of devices
and physics. We consider applications for such super-silicon devices, showing
that the state-of-the-art transmon qubit and the sought-after phase-slip qubit
can both be realized. The latter qubit leverages the natural high kinetic
inductance of these materials. Building on this, we explore how kinetic
inductance based particle detectors (e.g., photon or phonon) could be realized
with potential application in astronomy or nanomechanics. We discuss super-semi
devices (such as in silicon, germanium, or diamond) which would not require
atomistic fabrication approaches and could be realized today.
