Superconductivity in hyperdoped Ge by molecular beam epitaxy

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