Superconductivity in Nanowire Devices Formed by Al-Si Exchange

Development of devices that contain both superconducting and semiconducting components on a single chip is an important area of investigation for emerging quantum technologies. We have investigated superconductivity in nanowire devices fabricated using the Al-Si exchange process in silicon-on-insulator wafers. Aluminum from deposited contact electrodes undergoes an Al-Si exchange process with prepatterned Si nanowire device structures along the entire length of the nanowire, over micrometer length scales and at temperatures well below the Al−Si eutectic. The phase-transformed material is conformal with the predefined device patterns. In magneto-transport measurements, nanoring structures formed by this fabrication process exhibit periodic features in the differential resistance and in the critical current that result from fluxoid quantization. The retrapping current also exhibits oscillations. The devices can be operated in temperature/magnetic-field regimes where some components of the device are in the superconducting state while others are in a resistive state. Under these conditions the magneto-transport data exhibit more complex features which may provide insight into how these mixed-state devices could be further developed for uses in magnetometry and other quantum technologies. The details of the Al-Si exchange process also suggest that it could allow a range of new nanoscale superconducting-semiconducting device structures to be formed. In this presentation, our exploration of these superconducting nanowire devices and their promise for quantum technologies development will be discussed.