Equilibrium and non-equilibrium hydrogen coverages on vicinal Si(001) surfaces: Diffusion barriers and binding energies

By: M. B. Raschke and U. Höfer

Physical Review B 59, 2783 (1999)

The surface kinetics of hydrogen adsorbed on vicinal Si(001) surfaces, misoriented towards the (110) direction, is investigated by means of optical second-harmonic generation. Following the selective saturation of the double-height DB steps by exposing the surface to a well-defined dose of molecular hydrogen, the transition from this nonequilibrium to an equilibrium hydrogen distribution is monitored in the temperature range between 580 and 730 K. A thermally activated diffusion process with a barrier of 1.7 +/- 0.15 eV associated with the step depletion is observed. From measurements of the equilibrium hydrogen coverage the steps are found to be energetically favored with a H2-chemisorption energy difference of ∼0.2 eV between step and terrace sites.