Characterization of Thin MgO Films on Ag(001) by Low-Energy Electron Diffraction and Scanning Tunneling Microscopy

The evolution of the MgO(001) film morphology on Ag(001) was studied in dependence on the growth temperature (373-673 K) and grown MgO quantity (0.2-2 ML) by low-energy electron diffraction and scanning tunneling microscopy. We evidence an island growth mode of MgO for all temperatures. At 373 K, the MgO film exhibits a high island density, which is due to a too small surface mobility of the film compounds during the film growth. At a growth temperature of 673 K, silver hampers a perfect growth of MgO islands due to its high mobility, which leads to dendrites of MgO. The flattest and. largest MgO islands are obtained at a growth temperature of around 573 K, which is a compromise guaranteeing a sufficiently high Mg or MgO mobility but also an enough low diffusion of silver.