Gold-Germanium Based Ohmic Contacts to the Two-Dimensional Electron Gas at Selectively Doped Semiconductor Heterointerfaces

Results of a study of Ohmic contacts to the two dimensional electron gas (2DEG) at N sup (+) -n III-V semiconductor heterointerfaces are presented. In a comparison of alloyed metallizations based on the Au-27 at.% Ge eutectic system, the addition of Ni and method of deposition were found to have the largest effects in lowering the contact resistance. The Ni-Ge-Au Ohmic contact reproducibly gives a (width-normalized) contact resistance of less than 0.2 OMEGA- mm, which is adequate for MESFET applications using these structures.