Influence of Pt atoms on the low temperature formation of epitaxial Pd monosilicide

The effect of Pt concentration in Pd thin films on the nucleation and growth of PdSi and Pd_xPt_1-xSi (ternary monosilicide) has been investigated by transmission electron microscopy (TEM). Low concentration of Pt (10 at. %) in Pd film enhances PdSi formation at lower temperature than previously reported. It has been proposed that PdSi formation is governed by its slow nucleation. However, in our studies, the nucleation of PtSi, which is substituted for that of PdSi, triggers the subsequent PdSi growth at low temperatures. High concentration of Pt (55 at. %) in Pd-Pt alloy film lowers the temperature of the phase transformation from metal-rich silicide to monosilicide (Pd_xPt_1-xSi). The temperature is the same as that of PtSi formation. In both cases, the monosilicide layers (about 20 nm) have an epitaxial relationship with (111) Si substrates.