A Reproducible Process For Mesoscopic Superconducting Indium Contacts To Gaas/Algaas Heterostructures

In this report we present a procedure to fabricate high transmissive superconducting (S) contacts by diffusing indium into GaAs/Al(x)Ga(1-x)As based high-mobility two-dimensional electron gas (2DEG). We use a thermostable trilayer resist for indium lift-off. By doing electrical measurements at low temperature and transmission electronic microscopy observations, we show that the current through the S/2DEG interface is carried by a few number of localized indium filaments providing a good contact with the 2DEG. The low dimensional nature of those filaments is characterized by phase slip centers in the I(V) curve of a shunted S/2DEG/S junction. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3153983]