Metal Co-Adsorption Induced √21×√21 Superstructure on Si(111) Surface Studied by Reflection High-Energy Positron Diffraction

The Ag adsorption induced √21×√21 superstructure on the Si(111)-5×2-Au structure at high temperature, namely √21×√21-(Au,Ag), has been studied using reflection high-energy positron diffraction. The profiles of the rocking curves and the intensity distributions in the diffraction pattern are similar to those from the Ag or Au adsorption induced √21×√21 superstructure (√21×√21-Ag and √21×√21-(Ag,Au)) on the Si(111)-√3×√3-Ag structure below room temperature. Assuming all of the adsorption atoms as the Ag atoms, we analyzed the atomic structure of the √21×√21-(Au,Ag) surface on the bases of the dynamical diffraction theory. We found that the structure model is almost the same as the √21×√21-Ag and √21×√21-(Ag,Au) surfaces. [DOI: 10.1380/ejssnt.2009.432]