SUPERCONDUCTOR-SEMICONDUCTOR JUNCTIONS WITH INAS AL(GA)SB QUANTUM-WELLS/

We report on the fabrication and the electrical characterization of th e superconductor (Pb alloy)-semiconductor (InAs) junctions. Submicron scale superconducting weak link devices were fabricated on InAs/AlGaSb . The contact resistance of sequentially evaporated In/Pb/In and An/Pb /In electrodes were reduced to be 0.2 Ohm mm. The differential resista nce of the weak link devices measured between 2.6 and 5.5 K revealed m ultiple Andreev reflection indicating ballistic carrier transport in t he superconductor-semiconductor junction. The modulation of conductanc e across the superconducting electrodes has been demonstrated on the P b alloy-InAs structure for the first time by applying gate bias voltag es at 4.2 K.