  Silicon-based color-centers (SiCCs) have recently emerged as quantum-light
sources that can be combined with telecom-range Si Photonics platforms.
Unfortunately, using current SiCC fabrication, deterministic control over the
vertical emitter position is impossible due to ion-implantation's stochastic
nature. To overcome this bottleneck towards high-yield integration, we
demonstrate a radically innovative creation method for various SiCCs, solely
relying on epitaxial growth of Si and C-doped Si at atypically-low temperatures
in a ultra-clean growth environment. These telecom emitters can be confined
within sub-1nm thick layers embedded at arbitrary vertical positions within a
highly crystalline Si matrix. Tuning growth conditions and doping, different
SiCC types, e.g., W-centers, T-centers, G-centers, or derivatives like
G'-centers can be created, which are particularly promising as Si-based
single-photon sources and spin-photon interfaces. The zero-phonon emission from
G'-centers can be conveniently tuned by the C-concentration, leading to a
systematic wavelength shift and linewidth narrowing towards low emitter
densities.
