Observation of lattice fringes of the Si(111)–7×7 structure by reflection electron microscopy*

Lattice fringes of Si(111)–7×7 reconstructed surface structure in reflection electron microscopy (REM) are observed for the first time, and their characteristic features are presented. Due to a glancing reflection condition in REM, the fringes with a spacing of 2.3 nm of the 7×7 surface structure lattice are seen in a region of a certain defocus range (about 6–8 μm) in a foreshortened image. The glancing reflection geometry also results in a complicated dependence of fringe directions on imaging conditions (beam alignment, crystal orientation). A shift of the fringes across the surface atomic steps and out of phase boundaries is observed.