Study of interface formation on Co/Si(111)-7 x 7 using angle-resolved photoemission
The electronic structure of epitaxial layers of CoSi/sub 2/ on Si(111) substrates is of intense scientific interest both because these structures offer the possibility of novel high-speed electronic devices and because they are excellent model systems for understanding the systematics of epitaxial growth and of Schottky barrier formation. We have studied electronic structure using angle-resolved UV photoemission on three types of silicon--silicide samples: a thick CoSi/sub 2/ layer with CoSi/sub 2/--Si termination, thinner layers with CoSi/sub 2/--Co termination, and unannealed submonolayer deposits of Co on Si(111). The CoSi/sub 2/--Si sample shows electronic states in very close agreement with the energy bands for bulk CoSi/sub 2/ computed by Mattheiss and Hamann. The CoSi/sub 2/--Co samples have similar bulk states, but their outermost layers show a shift by 0.5 eV toward E/sub F/ of the Co(3d) states, apparently because the outermost Co atoms are less strongly reacted with Si. A state at -3 eV is found and attributed tentatively to an interface state of the Si(111)/CoSi/sub 2/ interface formed at 450 /sup 0/C. The electronic structure of unannealed deposits indicate a strong reaction between Co and Si. This suggests similarities between the bonding environment of the deposited Co and that of the outermost Co on the CoSi/sub 2/--Co surface.
- Research Organization:
- School of Applied Physics and Engineering, Cornell University, Ithaca, New York 14853
- OSTI ID:
- 6181943
- Journal Information:
- J. Vac. Sci. Technol., A; (United States), Vol. 7:3
- Country of Publication:
- United States
- Language:
- English
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