Schematic illustrations of (a) silicon-silicon bond dissociation and [(b)–(d)] silicon-hydrogen bond dissociation. The curved arrows illustrate the flow of electrons. We show only paths leading to chemisorption at silicon germanium intradimer sites. Similar structures hold for the corresponding interdimer paths and for germanium germanium sites. The larger empty circles denote silicon atoms, the large filled circles denote germanium atoms, and the smaller circles denote hydrogen atoms. We investigate only the cases where the germanium atom is the buckled-up atom at the adsorption site.
The potential energy curves for the reaction paths investigated for (a) silicon-silicon bond dissociation silicon-hydrogen bond dissociation mechanisms (b) A, (c) B, and (d) C. For each mechanism, the upper panel shows the results for adsorption at a silicon germanium site and the lower panel shows the results for adsorption at a germanium-germanium site. No precursor states were found for any of the paths we examined.
The potential energy curves for the reaction between adsorbed and an adsorbed hydrogen atom to form an adsorbed and a silane molecule that desorbs from the surface. The calculation was done for a silicon germanium site. Structure 1 is adsorbed and H.
The results for adsorption energy and barrier are tabulated here for each path and adsorption site. For each adsorption site, the first column is the adsorption energy and the second column is the adsorption barrier. For the SiSi site, results from Cheng et al. (Ref. 22) are included for comparison. Energies are in eV.
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