The achievement of low contact resistance to indium phosphide: The roles of Ni, Au, Ge, and combinations thereof

摘要

We have investigated the electrical and metallurgical behavior of Ni, Au-Ni, and Au-Ge-Ni contacts on n-InP. We have found that very low values of contact resistivity rho(sub c) in the E-7 omega-sq cm range are obtained with Ni-only contacts. We show that the addition of Au to Ni contact metallization effects an additional order of magnitude reduction in rho(sub c). Ultra-low contact resistivities in the E-8 omega-sq cm range are obtained with both the Au-Ni and the Au-Ge-Ni systems, effectively eliminating the need for the presence of Ge in the Au-Ge-Ni system. The formation of various nickel phosphides at the metal-InP interface is shown to be responsible for the observed rho(sub c) values in the Ni and Au-Ni systems. We show, finally, that the order in which the constituents of Au-Ni and Au-Ge-Ni contacts are deposited has a significant bearing on the composition of the reaction products formed at the metal-InP interface and therefore on the contact resistivity at that interface.