The possibility of realizing anyons in solid state physics [243, 365] fuels the development of superconductor semiconductor hybrid structures. A host of physical phenomena, which are rooted in the interaction between superconductors and semiconductors, have produced spectacular experimental results [5, 102, 127, 235]. Theoretical treatise [101, 243, 293] raise expectations, conditioned on continued material improvement. The state of the art of epitaxial superconductor - semiconductor materials, are Aluminum thin films deposited in the molecular beam epitaxy machine after growth of the semiconductor [180], whose superconducting properties limit the experimental work. A DC magnetron sputtering system was built and connected to two molecular beam epitaxy machines, to deposit superconductors with improved properties on the semiconductors without breaking vacuum. This enables oxide free interfaces, which are necessary to achieve epitaxy of the superconductor on the semiconductor. DC magnetron sputtering can deposit low vapor pressure metals at low temperatures. Furthermore, it provides a wide variety of possible compound materials and versatility in tuning the deposition parameters. The system had to be custom built, due to the stringent ultra high vacuum conditions set by the molecular beam epitaxy machines. The deposition of niobium on gallium arsenide with the new DC magnetron system was investigated as a function of deposition power and the effect of the interface oxide. The thereby calibrated films are studied in their charge transport behavior across the superconductor semiconductor interface and showed signatures of Andreev reflection. First results from experiments using the semiconductor-superconductor hybrid materials are presented. The magnetic field mediated interaction between the type II superconductor niobium and a two dimensional electron system in gallium arsenide have been investigated. The semiconductor structure grown by molecular beam epitaxy is based on shallow inverted two dimensional electron systems in gallium arsenide, previously optimized in the group [183, 184]. After the deposition of the superconductor, the material was processed into a Hall structure with self-aligned contacts and a global backgate. The samples show the typical Hall and Shubiknov deHaas traces associated with a two dimensional electron gas and the niobium is still superconducting. However, there are no signatures of an interaction between the type II superconductor and the two dimensional electron gas. This is likely due to the dirty limit niobium and the high electron density in the two dimensional electron gas
