Ohmic contacts to n-GaAs and n-In(0.53)Ga(0.47)As: A thermodynamic approach

The fundamentals of the physics on metal/semiconductor contacts were reviewed. Various mechanisms for the formation of ohmic contacts to n-GaAs were summarized from a metallurgical point of view, while the exchange mechanism was treated in detail as it can lead to the formation of electrically and thermally reliable contacts with consistently simple metallurgy. A thermodynamic approach was utilized in the design of thermally stable ohmic contacts to n-GaAs and n-{dollar}rm Insb{lcub}0.53{rcub}Gasb{lcub}0.47{rcub}As.{dollar} By examining the phase equilibria in the relevant systems, the metallizations for n-GaAs were chosen so that they fit into the thermodynamic framework for the exchange mechanism to possibly operate; while thermodynamically stable phases were the choices for n-{dollar}rm Insb{lcub}0.53{rcub}Gasb{lcub}0.47{rcub}As{dollar} metallizations. The actual contacts were fabricated. Their electrical properties were characterized by the specific contact resistance. The interfacial characterizations were also performed on the contacts. The mechanism of the contact formation was then analyzed, and its consistency with the thermodynamic design was evaluated.