Paper: 1999 Effect of beam energy and surface temperature on the dissociative adsorption of H2 on Si(001)

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

M. Dürr, M.B. Raschke, U. Höfer
The Journal of Chemical Physics 111 (23), 10411-10414
DOI PDF

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.