Effect of beam energy and surface temperature on the dissociative adsorption of H2 on Si(001)
Reviews and Highlights | Quantum Science | Molecular and Soft-matter | Ultrafast Nano-optics and Nanophotonics | Mineralogy and Geochemistry |
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M. Dürr, M.B. Raschke, U. Höfer
The Journal of Chemical Physics 111 (23), 10411-10414
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Dissociative adsorption of H2 from a high-flux supersonic molecular beam on flat and vicinal Si(001) surfaces was investigated by means of optical second harmonic generation (SHG). The initial sticking coefficients for terrace adsorption varied between 10-8 and 10-4. They revealed a strongly activated dissociation process, both with respect to the kinetic energy of the incident molecules (70 meV ≤ Ekin ≤ 380 meV) and the surface temperature (440K ≤ Ts ≤ 670 K). The results indicate that dynamical distortions of Si surface atoms can lower the effective adsorption barriers from 0.8±0.2 eV to almost negligible values. Previously proposed defect-mediated processes can be ruled out as a major adsorption channel.