Reflection Electron Microscope Observations of Dislocations and Surface Structure Phase Transition on Clean (111) Silicon Surfaces

Abstract

A recently reported surface study by means of ultra-high-vacuum reflection electron microscopy (Osakabe et al. : Surf. Sci. in press) was extended to further details of clean (111) silicon surfaces. A screw dislocation emergent at the surface was clearly identified as the place at which one surface step terminates with a characteristic line contrast. In the transformation between the (7×7) and (1×1) surface structures across 830°C, the surface steps act as nucleation sites : on cooling the (7×7) structure nucleates at the upper edge of the steps and grows along the upper terraces, while on heating the reversed process takes place.