FABRICATION OF HYBRID SUPERCONDUCTOR-SEMICONDUCTOR NANOSTRUCTURES BY INTEGRATED ULTRAVIOLET ATOMIC-FORCE MICROSCOPE LITHOGRAPHY

Hybrid superconductor-semiconductor (S-Sm) nanostructures were fabrica ted by integrating standard ultraviolet photolithography and direct pa tterning of photoresist with an atomic force microscope (AFM). This no vel technology was used to fabricate Nb-InAs-Nb weak links comparable in length to the coherence length. These structures exhibit high criti cal currents up to 10 mu A/mu m in planar geometry at 0.3 K. The fabri cation protocol is based on the modification of photolithographically defined patterns by AFM static ploughing of the photoresist. Wet chemi cal etching is subsequently used for the definition of nanoscale S-Sm- S bridges. Additionally Lift-off procedures allowed the fabrication of submicron superconducting bridges. Successful fabrication of the nano structures was verified by electrical characterization and by AFM and scanning electron microscope structural characterization. (C) 1997 Ame rican Vacuum Society.