Superconductivity in silicon-gallium alloys

Superconducting silicon-gallium (SiGa) is a promising new material with superconducting transition temperature above liquid helium temperature. SiGa can be fabricated with methods already utilized in semiconductor industry and it also enables superconductor-semiconductor hybrid structures.

In this thesis, fabrication and characteristics of superconducting SiGa alloy, fabricated via maskless focused ion beam (FIB) gallium implantation, with planar geometries including both low and high aspect ratio limits. Samples with variable implantation parameters were fabricated and characterized.

First, the FIB etch rates of silicon and silicon dioxide were determined. Additionally, implantation parameters including Ga ion dose, beam blur and pitch were optimized during the study. Next, superconductivity was demonstrated both in broad areas and nanowires with superconducting transition temperature of approximately 6.3 K. Finally, implant modulation via resist based masking was studied but unfortunately the investigated method was not found to be viable.