Step-by-step Investigation of Atomically Flattening Processes of Au(111) Single Crystal Surfaces

Abstract

Flattening processes of a commercially available Au(111) single crystal surface were step-by-step investigated using atomic force microscopy (AFM), scanning tunneling microscopy (STM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS) from a micron scale to an atomic dimension. AFM images in a micron scale showed that there were many scratches with a few nm depth on the as-received Au(111) disk surface. SEM, EDX, and XPS results indicated that there were surface contaminations such as carbon and silicon species. As a first, these contaminations could be removed by dipping the disk in concentrated H2SO4 and then in boiling concentrated HF. The scratches described above were disappeared after annealing by a gas flame, which is a most popular method for Au(111) single crystal preparation. After the electrochemical polishing and annealing in an electric furnace under argon atmosphere, finally, atomically flat Au(111) surfaces with dimensions of more than 500 × 500 nm2 were obtained. With increasing of annealing period, larger terraces were obtained.