Ni/Si(111) system: Formation and evolution of two- and three-dimensional phases studied by spectromicroscopy

The spatial variations in the composition and electronic structure of Ni/Si interfaces formed via reactive epitaxy at 830 K and successively annealed to 950 K have been studied by synchrotron-radiation scanning photoelectron microscopy, a method that combines chemical mapping with photoelectron spec troscopy from selected spots of the surface. The combination of submicron s patial resolution (less than or equal to 0.15 mu m) with high energy resolu tion allowed us to characterize the coexisting phases including micron-size d silicide islands and two-dimensional structures. Deposition of 0.7 ML Ni at 830 K produced domains of the root 19 phase with different Ni concentrat ion, coexisting with NiSi and NiSi2 islands. Annealing this interface to 95 0 K led to conversion of the root 19 to a (1 x 1)-RC structure (where RC is ring cluster), which appears to be more uniform than the root 19 surface. From the chemical maps and the Si 2p, Ni 3p, and valence-band spectra corre sponding to the coexisting phases the nature of the phases was determined a nd the mechanism of the Ni mass transport on the root 19 and (1 x 1)-RC sur faces was examined. [S0163-1829(99)08903-1].