  Superconducting germanium films are an intriguing material for possible
applications in fields such as cryogenic electronics and quantum bits.
Recently, there has been great deal of progress in hyperdoping of Ga doped Ge
using ion implantation. The thin film growths would be advantageous allowing
homoepitaxy of doped and undoped Ge films opening possibilities for vertical
Josephson junctions. Here, we present our studies on the growth of one layer of
hyperdoped superconducting germanium thin film via molecular beam epitaxy. We
observe a fragile superconducting phase which is extremely sensitive to
processing conditions and can easily phase-segregate, forming a percolated
network of pure gallium metal. By suppressing phase segregation through
temperature control we find a superconducting phase that is unique and appears
coherent to the underlying Ge substrate.
