Superconducting layers by gallium implantation and short-term annealing in semiconductors

Superconducting layers in silicon and germanium are fabricated via gallium implantation through a thin SiO₂ cover layer and subsequent rapid thermal annealing. Gallium accumulation at the SiO₂/Si and SiO₂/Ge interfaces is observed but no pure gallium phases were found. In both cases superconducting transition occurs around 6 – 7 K which can be attributed to the metallic conduct-ing, gallium rich interface layer. However, the superconducting as well as the normal-state transport properties in gallium overdoped silicon or germanium are different.