HIGH-TEMPERATURE SCANNING-TUNNELING-MICROSCOPY OBSERVATION OF PHASE-TRANSITIONS AND RECONSTRUCTION ON A VICINAL SI(111) SURFACE

The step structure of a vicinal Si(111) surface misoriented 10-degrees to [112BAR] is studied using high-temperature scanning tunneling micr oscopy (STM). Phase transitions on the vicinal Si(111) surface are obs erved in real time on an atomic scale. During cooling from above the ( 1 X 1)-to-(7 X 7) transition temperature, slender (111) facets with a 7 X 7 structure appear, and these facets widen as the temperature decr eases. At the initial stage of step bunching, no surface reconstructio n is observed on the step bunch. Below 700-degrees-C, however, nucleat ion of reconstructed (331) facets starts on the step bunch. These STM results are compared with our previous reflection high-energy electron -diffraction results