Synchrotron x-ray scattering studies of semiconductor (111) surface reconstruction

Some unifying principles of the mechanisms governing reconstruction at semiconductor surfaces will be discussed. Sources of synchrotron x-radiation are then shown to be an important asset in the problem of surface structure determination. Three recent examples of the application of x-ray diffraction techniques to semiconductor (111) surfaces will then be presented to illustrate the general remarks. (i) A structure determination of the InSb(111) surfaces shows very clear evidence of charge transfer leading to valence change in the top two layers of the structure. (ii) Structural analysis of the famous Si(111) 7×7 reconstructed is discussed in the light of certain models. (iii) A 7×7 state of Ge(111) seen in epitaxial films of Ge on Si(111) is attributed to compressive strain.