Fabrication of Superconducting Transistors using InAs/(AlGa)Sb Quantum Wells

We report on a fabrication process of superconducting weak links and superconducting transistors, which contain two-dimensional electrons in InAs/(AlGa)Sb quantum well. The superconducting transistors with lead alloy superconducting contacts were fabricated by using electron beam lithography, lift-off, and wet chemical etching processes. We have succeeded in fabricating a superconducting transistor with 0.4 µ m channel length and 0.17 µ m gate length between superconducting electrodes. Although the ideal performance of superconducting transistors has not been achieved yet, we present the results of superconducting weak links. The process of reducing contact resistance between lead alloy and InAs is also discussed, which is crucial to demonstrate the performance of the superconducting transistor.