Superconducting weak link devices using lead alloy-InAs/AlGaSb heterostructures

Fabrication and transport properties of InAs/AlGaSb superconducting weak link devices are reported. Transport properties of two terminal devices have been measured between 2.6 K and 5.5 K, and oscillations of differential resistance due to multiple Andreev reflection have been observed. The three terminal device with a gate showed good FET performance with transconductance of 314 mS/mm at 4.2 K although superconducting current has not been modulated on the device for gate length of 0.74 /spl mu/m. The process to reduce contact resistance between the PbIn alloy and InAs is also discussed, which should be crucial to demonstrate the superconducting transistor.