Abstract
In order to clarify the structure of high-temperature phase of Si(111)(2√3×2√3)R30°–Sn surfaces, in situ scanning tunneling microscopic observations were performed. The study led to important findings that the high-temperature phase is not a (1×1) structure but a disordered one and that the (2√3×2√3)R30° structure changes to the disordered one through a high-temperature (2√3×2√3)R30° structure newly found. A model for the (2√3×2√3)R30° structure at room temperature was proposed through an ab initio structure relaxation calculation, which can explain well the features of diffraction intensity, Paterson function and scanning tunneling images of the (2√3×2√3)R30° structure.