Anisotropic structural modulation of epitaxial Au(111) thin films on striped Ag substrates

Au films grown on striped substrates [Ag/Si(111)-(4x1)-In] acting as an atomic-scale geometrical template were studied by scanning tunneling microscopy, low-energy electron diffraction and Auger electron spectroscopy. The two-step growth method, consisting of low-temperature deposition followed by a mild annealing to room temperature, was employed to form the Au films. The Au films grow in a layer-by-layer fashion on the atomically striped Ag substrates. Scanning tunneling microscope images reveal that the Au films are anisotropically modulated at the initial stage of the growth with stacking-fault induced steps on the Ag substrate. These steps, however, do not form uniformly throughout the surface, and their density decreases with increasing Au coverage due to higher stacking-fault energy of Au. These observations indicate the importance of low stacking-fault energy for the growth of atomic-scale periodic stripe structure.