Formation of Al/Au Bimetallic Interface Studied by Angle-Resolved X-Ray Photoelectron Spectroscopy (ARXPS)

Abstract

ARXPS (Angle-resolved X-ray photoelectron spectroscopy) measurements were performed on the thin aluminum films deposited on the gold polycrystalline substrate kept at the temperature of liquid nitrogen in order to characterize the interdiffusion process during early stages of Al/Au interface formation. The intermixing of Al and Au elements at Al/Au bimetallic interface occurred already at temperature of liquid nitrogen leading to the formation of the well-resolved component on the high binding energy side of Au(4f) core line corresponding to AlAu intermetallic phase. The formation of initial AlAu phase at Al/Au interface in our experimental conditions can be explained on the base of its thermodynamic stability. The sample annealing resulted in the growth of the amount of AlAu intermetallic compound formed at liquid nitrogen temperature with subsequent decomposition of the parent alloy phase and formation of AlAu2 intermetallics richer in Au atoms. Tikhonov regularization method was used to extract the aluminum in-depth concentration profile from the measured ARXPS intensities. L-curve analysis was applied to determine the regularization parameter.