Subsurface dimerization in III-V semiconductor (001) surfaces

We present the atomic structure of the c(8 X 2) reconstructions of InSb-, I nAs-, and GaAs-(001) surfaces as determined by surface x-ray diffraction us ing direct methods. Contrary to common belief, group III dimers are not pro minent on the surface, instead subsurface dimerization of group m atoms tak es place in the second bilayer, accompanied by a major rearrangement of the surface atoms above the dimers to form linear arrays. By varying the occup ancies of four surface sites the (001)-c(8 X 2) reconstructions of III-V se miconductors can be described in a unified model.