Structural study of Si(111)(2√3 x 3√3)R30°-Sn surfaces

In order to clarify the structure of high-temperature phase of Si(111)(2root3 x 2root3)R30degrees-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 x 1) structure but a disordered one and that the (2root3 x 2root3)R30degrees structure changes to the disordered one through a high-temperature (2root3 x 2root3)R30degrees structure newly found. A model for the (2root3 x 2root3)R30degrees 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 (2root3 x 2root3)R30degrees structure.