At 400 K, the absolute coverage of hydrogen (deuterium) adsorbed on the Si(100)-2×1 surface for different hydrogen-induced surface reconstruction phases was determined by nuclear reaction analysis and low-energy electron diffraction. The transition from a monohydride 2×1 phase to a dihydride plus monohydride 3×1 phase results in a distinct plateau on the curve of coverage versus exposure. With increasing atomic hydrogen (deuterium) exposure the coverage increases to about 1.7 monolayers with concomitant deterioration of the 3×1 phase, indicating etching of silicon backbonds. Prolonged exposure leads to an effective saturation coverage of 1.6±0.1 monolayers with further degradation of the 3×1 symmetry.

• Received 11 May 1993

DOI:https://doi.org/10.1103/PhysRevB.48.4952