High-temperature scanning tunneling microscopy study of Si(111) surface structure changes caused by Ga surface diffusion

In order to clarify dynamical transition behaviors among Ga-induced superstructures' on Si(111) surface, a Ga block was placed on a Si(111) surface elevated at 175degreesC and 500degreesC and surface structure changes caused by Ga surface diffusion from the Ga block were in-situ studied by high-temperature scanning tunneling microscopy. Successive structure changes from 7 x 7 dimer adatom stacking-fault (DAS) to 6.3 x 6.3 structure through alpha'-7 x 7 were observed in detail on the Si(111) surface at 170degreesC. No intermediate structure appeared between 7 x 7 DAS and (root3 xroot3)R30 structures on the Si(111) surface at 500degreesC.