Observation of (5×5) Surface Reconstruction on Pure Silicon and its Stability Against Native-Oxide Formation

We report the observation of a (5×5) reconstruction on the pure Si (111) surface, which is induced and stabilized by a tensile strain. The stabilization is so strong that the reconstruction survives extended exposure to air and the formation of a native oxide layer. Modeling of experimental high-resolution transmission-electron-microscope profile images indicates that the native oxide is ordered. The (5×5) reconstruction can also be induced at an initially unreconstructed Si-oxide interface by application of tension and appropriate annealing.