Electrical and metallurgical behavior of Au/Zn contacts to p -type indium phosphide

The metallurgical and electrical behavior of Au/Zn contacting metallization on p-type InP is investigated as a function of the zinc content in the metallization. It was found that ohmic behavior can be achieved with Zn concentrations as small as 0.05 at. % Zn. For Zn concentrations between 0.1 and 36 at. % the contact resistivity was found to be independent of the Zn content. For low Zn concentrations the realization of ohmic behavior was found to require the growth of the compound Au2P3 at the metal-InP interface. The magnitude of the specific contact resistivity is shown to be very sensitive to the growth rate of the interfacial Au2P3 layer. The possibility of exploiting this sensitivity to provide low-resistance contacts while avoiding the semiconductor structural damage that is normally attendant to contact formation is discussed. Evidence is presented, finally, that the presence of Zn in the Au-Zn/p-InP contact system lowers the contact resistivity by effecting an increase in the work function of the Au2P3 interfacial layer.