Metal/SI GaAs/Metal systems: Demonstration of unpinning of the Fermi level at the interface

The work reports on the study of metal/semi-insulating GaAs/metal systems with different contacts: Mg, Gd, In and AuGeNi eutectic. Charge carrier transport through the interface is characterized by the current-voltage measurements. Observed results: i) opposite generally accepted “ohmic, bulk limited” charge transport at low bias, ii) are in contradiction with the thermionic emission model of charge transport in M-SI GaAs, and iii) demonstrate the unpinning of the Fermi level at the M-SI GaAs interface.