Abstract :
In this thesis, I present work made on several different types of devices each of
which permit us to understand fundamental properties about the material quality
of the Ge/SiGe heterostructure itself or some physics related to the inter-play of
device geometry, semiconductor properties and superconductivity. I have designed,
fabricated, and measured devices such as Hall-bars, Josephson junction field effect
transistors (JOFETS), gate-tunable superconducting transmons (gatemon), and
quantum-point contacts (QPC) in proximity to a super/semi contact.
Initial results on Hall-bars and JOFETS guide the design of more advanced
devices such as the gatemon superconducting qubit or in using QPCs to probe the
nature of the superconducting proximity effect in Ge. Overall, this work presents
a study of our material system of aluminium contacts to Ge quantum wells in
SiGe heterostructures specifically in the context of superconductor semiconductor
hybrid devices using the current strategy of fabricating devices and contacts here.
Comparisons with other materials are made where possible to put these results in
context.