Transport properties of ultra-scaled Ge/Si core/shell nanowires with highly transparent Al contacts.

Superconducting-semiconducting hybrid systems provide a rich domain for the investigation of electronic and quantum transport. Further, promising developments in their application in high performance nanoelectronics and quantum devices has motivated significant research and development. Nanowire heterostructures are of particular interest due to their quantum confinement properties allowing one to investigate transport in quasi one-dimensional systems. However, critical to their success is the fabrication of high quality and reproducible semiconductor-superconductor interfaces. Using a novel annealing technique, we have realised nanowire heterostructures consisting of crystalline-Al/Si core/shell leads contacting tuneable Ge/Si core/shell segments with atomically precise interfaces. We will present results of temperature dependent DC transport measurements on ultra-scaled devices. Reporting on the gate tuneable transport properties of these highly transparent devices including quantized conductance, tuneable Josephson current and multiple Andreev reflections and their applications as quantum devices.