3-D STRUCTURAL ANALYSIS OF AG/SI(111) INTERFACES BY X-RAY DIFFRACTION. R. D. Aburano, Hawoong Hong, J. M. Roesler, K.-S. Chung, H. Chen and T.-C. Chiang, University of Illinois, and P. Zschack, ORISE.

The interface of the "prototypical nonreactive" Ag/Si(111) system exhibits different structures depending upon the interfacial preparation. Room temperature deposition of a Ag film on a clean Si(111)-(7x7) surface results in a Ag-modified (7x7) structure at the interface. This structure transforms to a bulk-like (1x1) structure when annealed above 200deg.C. This temperature is characteristic for the formation of the (3x3)R 30deg.-Ag reconstruction which is commonly observed for a monolayer of Ag adsorbed on Si(111). This (3x3)R 30deg.-Ag reconstruction is also not retained at the interface even when it is buried under a room temperature deposited Ag film. Crystal truncation rod analysis of the Ag-modified (7x7) and (1x1) structures revealed the preservation of the Si stacking fault in the former and a Ag-Si mixed layer at the interface in the latter. These results may provide some insight into the observed Shottky barrier height difference for these two interfaces.