Characterization of the (0001) cleavage surface of antimony single crystals using scanning probe microscopy: Atomic structure, vacancies, cleavage steps, and twinned interlayers

Abstract

Atomically resolved scanning tunneling microscopy images of the unreconstructed hexagonal structure of surface atoms on Sb(0001) are presented. Lateral and vertical lattice parameters have been determined. The interatomic spacing of 4.31 \AA{} $(\ifmmode\pm\else\textpm\fi{}0.05\AA{})$ on the Sb(0001) surface corresponds to the known bulk data. Cleavage has been found to occur always between adjacent double layers, yielding at least diatomic cleavage steps of 3.75 \AA{} $(\ifmmode\pm\else\textpm\fi{}0.10\AA{})$ height. Different kinds of defect structures on the cleavage plane have been imaged with atomic resolution. Point defects, caused by a single or by three missing surface atoms, have been uncovered. Stable imaging of cleavage steps, which were found to be straight along the atomic rows, has been achieved. Twinned interlayers formed upon cleavage of Sb even at room temperature have been revealed by atomic force microscopy. The mean twinning angle of $2.42\ifmmode^\circ\else\textdegree\fi{}$ $(\ifmmode\pm\else\textpm\fi{}0.20\ifmmode^\circ\else\textdegree\fi{})$ is quantitatively in accord with the value of $2.45\ifmmode^\circ\else\textdegree\fi{}$ predicted by the model of twinning in Sb crystals. The observed features are discussed with respect to other layered materials and with regard to their relevance for the use of Sb(0001) as a support of nanostructures.