ZnO Thin Film Structure Driven by Metal Surface Symmetry and Lattice Mismatch

In this work, we addressed the crystallographic structure of ultrathin zinc oxide films on metal single-crystal supports, namely, Pt(001) and Ag(111). The in-plane atomic arrangement gives rise to a low-energy electron diffraction pattern with 6 spots in hexagonal symmetry for the ZnO thin film on Ag(111) and 12 dots on a circle for the film on Pt(001) with surface lattice parameters of 0.34 and 0.33 nm, respectively. We observed that the ZnO film orientation and structure are driven by the underlying surface symmetry: wurtzite on Ag(111) and zinc-blende on Pt(001), as disclosed by high-resolution electron transmission microscopy. DFT calculations were used to predict the formation energy of ZnO thin films and their crystallographic structure stability. The results are promising for the engineering of ZnO thin films for different applications.