Insight into the Ehrlich-Schwoebel barrier via three-dimensional atomic force microscopy mapping of surface potentials on Au (111).

Thin film growth is a critical process enabling modern applications ranging from electronic devices to advanced coatings. Among the parameters that govern thin film growth, the Ehrlich-Schwoebel barrier stands out with its tight control over interlayer transfer and, consequently, kinetics-dominated film morphology. Despite its importance, the precise measurement of the Ehrlich-Schwoebel barrier remains complicated, presenting a critical impediment to rational thin film design. Here, we provide an insight into the Ehrlich-Schwoebel barrier over monoatomic step edges on Au (111) surfaces via three-dimensional atomic force microscopy (3D-AFM) with sub-nanometer spatial precision, minimizing the need for empirical model assumptions or theoretical calculations. Our measurements provide a quantitative, real-space view of the complex potential energy and force landscape near step edges, verifying the presence of energy barriers and wells at the top and bottom of step edges, respectively. The effect of the herringbone reconstruction on the potential energy landscape is also analyzed, revealing an enhancement of interactions near the elbows and a slight attenuation of the ridges.