Ohmic contacts of Pd/Zn/M(= Pd or Pt)/Au to p-type InP

Abstract

We have investigated the ohmic properties of Au/M(= Pd or Pt)/Zn/Pd/p-InP, focusing on the role of the third metal M in Au-free metallization. Both the lowest specific contact resistivity of 7 x 10(-6) Omega(.)cm(2) and a flat diffusion front were obtained for a sample with a Au/Pt/Zn/Pd/p-InP contact material after annealing at 400 degrees C for 4 min, indicating that the Pt layer was more effective than the Pd layer in preventing Zn out-diffusion during the annealing process. In addition to Au-free metallizations, we fabricated the Au-based metallization of Au/Cr/AuZn/Au/p-lnP in order to justify our ohmic contact process, and we compared its ohmic characteristics.