Two-dimensional ordering of pentafluorobenzenethiol self-assembled monolayers on Au(1 1 1) prepared by ambient-pressure vapor deposition

Formation and surface structures of pentafluorobenzenethiol (PFBT) self-assembled monolayers (SAMs) on Au(1 1 1) prepared by ambient-vapor phase deposition were examined by means of scanning tunneling microscopy (STM) as a function of deposition temperature. PFBT SAMs formed at room temperature have disordered phases with bright aggregated domains, which are very similar to benzenethiol SAMs. As deposition temperature increases to 50 °C, partially ordered domains and large aggregated domains appeared. High-resolution STM clearly revealed that PFBT SAMs formed at 75 °C were composed of long-range, two-dimensional (2D) ordered domains, which can be described as a c(2×√3) structure. The results of this study clearly demonstrate that deposition temperature is a crucial factor for obtaining PFBT SAMs on Au(1 1 1) with a high degree of structural order.