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\ifmmode^\circ\else\textdegree\fi{} to [112\ifmmode\bar\else\textasciimacron\fi{}] is studied using high-temperature scanning tunneling microscopy (STM). Phase transitions on the vicinal Si(111) surface are observed in real time on an atomic scale. During cooling from above the (1\ifmmode\times\else\texttimes\fi{}1)-to-(7\ifmmode\times\else\texttimes\fi{}7) transition temperature, slender (111) facets with a 7\ifmmode\times\else\texttimes\fi{}7 structure appear, and these facets widen as the temperature decreases. At the initial stage of step bunching, no surface reconstruction is observed on the step bunch. Below 700 \ifmmode^\circ\else\textdegree\fi{}C, however, nucleation of reconstructed (331) facets starts on the step bunch. These STM results are compared with our previous reflection high-energy electron-diffraction results [Jpn. J. Appl. Phys. 30, 1337 (1991)].