Formation, Lattice Alignment, and Coalescence of the Moiré Pattern of h-BN-Like Zinc Oxide on Ag(111)

Abstract

The properties of thin films largely differ from those of bulk material. Moreover, deviations from their idealized structure might influence their properties, both structurally and electronically. We characterize the formation of ultrathin zinc oxide (ZnO) layers on Ag(111) using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, low-energy electron diffraction, and scanning tunneling microscopy. Our study clarifies the film formation during reactive deposition, yielding a h-BN-like layer with a 7 × 7 superstructure, and reveals variations within the moiré pattern. The incomplete attenuation of the surface state, despite layer-by-layer formation, is attributed to silver patches within the ZnO layer, resulting from a diffusive Ag gas at the formation temperature of 600 K. Moreover, the nucleation of higher layers at domain boundaries highlights the importance of maintaining a low number of nuclei before the onset of film formation.