Fermi-Level Depinning of GaAs for Ohmic Contacts

In summary, we successfully demonstrate the unpinning of the Fermi level in n-GaAs through the insertion of an ultrathin insulator to reduce the penetration of MIGS from the metal into the semiconductor. We are able to transform the current from rectifying Schottky behavior, to increased conduction, to tunneling limited, simply by increasing the SiN thickness, verifying the ability for SiN to modulate the barrier height. A minimum contact resistance and maximum reverse current is obtained for a SiN thickness of 1.5 nm. We expect this method can be used to make non-alloyed low resistance ohmic contacts to n-GaAs, and can be applied to unpin other III-V Fermi levels.