Reversible phase transformation in the Pd2Si-PdSi thin-film system

Abstract

The thermal stability of thin PdSi films has been studied at temperatures ranging between 300 and 700 °C. The PdSi, when in contact with crystalline Si, transforms into Pd₂Si and Si at temperatures of 500–700 °C, a process contrary to the equilibrium‐phase diagram. The rate of transformation was found to depend on the structure and orientation of the Si. Upon heating above 750 °C, Pd₂Si transforms back to PdSi. However, PdSi is stable against annealing when in contact with Pd₂Si or an inert substrate SiO₂. We propose that the decomposition of PdSi into Pd₂Si and Si in the presence of crystalline Si is due to a lower interface energy of the Pd₂Si‐Si interface compared to that of the PdSi‐Si interface.