Two concepts of introducing thin-film superconductivity in Ge and Si by use of Ga-ion implantation

We report on two unconventional routes of embedding superconducting nanolayers in a semiconducting environment. Ion implantation and subsequent annealing have been used for preparation of superconducting thin-films of Ga-doped germanium (Ge:Ga) [1] as well as 10 nm thin amorphous Ga-rich layers in silicon (Si:Ga) [2]. Structural investigations by means of XTEM, EDX, RBS/C, and SIMS have been performed in addition to low-temperature electrical transport and magnetization measurements. Regarding Ge:Ga, we unravel the evolution of T_c with charge-charrier concentration while for Si:Ga recently implemented microstructuring renders critical-current densities or more than 50 kA/cm². Combined with a superconducting onset at around 10 K, this calls for onchip application in novel heterostructured devices.