Remarkable improvement in contact resistance property of the Ag-Pd alloy with oxide film by doping agents

In order to improve contact resistance properties of Ag-Pd alloy covered with contaminant films of oxide, Mg and Cr were used as additive dopants. For specimens of Ag(40 wt%)-Pd(60 wt%), Ag-Pd-Mg(0.1, 0.5, and 1.0 wt%), and Ag-Pd-Cr(0.1 and 0.5 wt%), formation and elemental compositions of oxide films thermally grown on the surface were examined by using electron diffractometry, X-ray photoelectron spectrometry (XPS) and ellipsometry. Then the effect of the oxide film on the contact resistance properties was clarified. The remarkable improvement of low contact resistance caused by the oxide film was found for Ag-Pd alloy with Mg dopant. However, for Cr dopant, the low contact resistance was not obtained as for the Ag-Pd alloy itself. The mechanism of this improvement was clarified by analysis of the film formation and its elemental compositions. As the composition of the film formed on the Ag-Pd-Mg alloy, PdO, MgO, and Ag were identified. On the contrary, for Ag-Pd-Cr, PdO, CrO, and Cr/sub 2/O/sub 3/ were found but not Ag. Moreover, for Pd-Ag, only PdO was found. Therefore, it is concluded that liberating Ag into the oxide film layer induced a remarkable improvement of the low contact resistance properties of the Ag-Pd alloy with Mg dopant.