Rocking curves of reflection high-energy positron diffraction from hydrogen-terminated Si(111) surfaces

Reflection high-energy positron diffraction experiments have been performed for Si(111) surfaces terminated with atomic hydrogen. From the rocking cur ve for the specular beam, the first to the fifth Bragg peaks were observed. The curve also showed an unanticipated dip in the total reflection region( theta<1.4 degrees), not found in the numerical analysis for the ideally hyd rogen-terminated flat surface. This difference is attributed to the scatter ing of positrons by roughness and/or SiH3 molecules on the surface, as conf irmed in further numerical analysis.