ATOMIC-STRUCTURE OF THE INSB(001)-C(8X2) RECONSTRUCTION DETERMINED BYX-RAY-DIFFRACTION

We report a surface X-ray diffraction study of the indium-rich InSb(00 1)-c(8 x 2) reconstruction, which gives for the first time a detailed picture of the atomic structure. A total of 96 in-plane (hk) reflectio ns were used to determine the structure in the surface plane. The out- of-plane atomic positions were found by measuring along three crystal truncation rods (CTRs) where the total intensity distribution is the r esult of interference between bulk and surface contributions. The deta iled analysis disproves the missing dimer model proposed from earlier PES and STM measurements. It shows that the reconstruction is deeper t han the Sb-rich c(4 x 4) and is composed of chains of In atoms running along the [110] axis, separated by pairs of Sb dimers on top of the S b-terminated bulk. The proposed structure is consistent with recent ST M images and represents a significant departure from the models previo usly suggested for the c(8 x 2) reconstruction on any of the III-V (00 1) surfaces. (C) 1998 Elsevier Science B.V. All rights reserved.