Atomic structure of the InSb(001)-c(4x4) reconstruction determined by X-ray diffraction

The atomic structure of the Sb-terminated InSb(001)-c(4 x 4) reconstruction has been determined using X-ray diffraction. A total of 132 in-plane reflections were used to determine the structure in the surface plane. The out-of-plane structure was calculated by measuring intensity profiles along four integer-order and two fractional-order diffraction rods. The primitive unit cell of the c(4 x 4) phase consists of a group of three symmetric Sb dimers chemisorbed onto a complete Sb layer. The groups are found to be incomplete in similar to 1/3 of the cases. The calculated bond length of the central dimer is 2.91+/-0.02 Angstrom. The outer dimers are extended with a separation of 3.14+/-0.02 Angstrom. The bond angles are indicative of sp(3)-type bonding. The data suggests that the reconstruction is limited mainly to the top layer, with only slight relaxation of the underlying bulk layers. (C) 1998 Elsevier Science B.V.