Equilibration of ring-cluster surface phases and silicide islands for Co adsorbed on Si(111)

• Published in: Surface science Vol. 431; no. 1; pp. 232 - 241
• Main Authors: Phaneuf, R.J., Bennett, P.A., Marsi, M., Günther, S., Gregoratti, L., Casalis, L., Kiskinova, M.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-07-1999; Amsterdam Elsevier Science; New York, NY
• Subjects: Cobalt; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Low energy electron microscopy (LEEM); Physics; Silicides; Silicon; Solid-fluid interfaces; Surface chemical reactions; Surface diffusion; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Synchrotron radiation photoelectron spectroscopy; Low energy electron microscopy (LEEM); Silicides; Surface chemical reactions; Silicon; Surface diffusion; Synchrotron radiation photoelectron spectroscopy; Cobalt; Semiconductor materials; Adsorption; Cobalt silicides; Surface reactions; Transition elements; Experimental study; Island structure
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(99)00359-3

We have used scanning photoemission microscopy (SPEM) and low energy electron microscopy (LEEM) to investigate the equilibration of the submonolayer surface phases and silicide islands formed in the reactive system Co–Si(111). Real-time LEEM images of the surface during annealing show an irreversible conversion of the close-packed, ordered
(
7
×
7
)
‘ring-cluster’ phase, into a lower density, disordered ‘(1×1)’ ring-cluster structure, which occurs surrounding the silicide islands. SPEM images and microscopically resolved photoemission spectra show directly that the islands are CoSi
2 and that they draw Co away from the nearby surface, resulting in the formation of the lower coverage phase. LEEM observations during extended annealing of the ‘(1×1)’-RC phase in the presence of these islands indicate a further depletion of the ‘(1×1)’-RC phase and the eventual formation of the (7×7) reconstruction.