X-ray determination of the GaSb(111)2x2 surface structure.

We have examined the GaSb(111)2x2 surface prepared by sputtering and annealing using grazing-incidence x-ray diffraction. Our structure factor analysis shows the similarity between this surface and the vacancy-buckling model for GaAs, GaP and InSb (111): it contains one Ga vacancy per unit cell and an adjustment of bond angles associated with valence change of the remaining surface atoms. Analysis of the integer-order intensities unambiguously determines the mode of attachment (registry) of the surface layer with the bulk crystal.