SYNTHESIS AND CHARACTERIZATION OF ULTRA-THIN MGO FILMS ON MO(100)

Ultra-thin MgO films have been synthesized under UHV conditions by evaporating Mg onto Mo(100) in various background pressures of oxygen. Low-energy electron diffraction (LEED) studies show that MgO films grow epitaxially in the 200-600 K substrate temperature range with the (100) face of MgO oriented parallel to Mo(100). The one-to-one stoichiometry of the MgO films has been confirmed using Auger electron spectroscopy (AES) and temperature programmed desorption (TPD). A typical loss pattern. characteristic of single-crystal MgO, has been obtained by high-resolution electron energy-loss spectroscopy (HREELS). At low oxygen pressures, the MgO film grows via a mechanism of island nucleation with domains that coexist with metallic Mg particles. The heat of sublimation of three-dimensional MgO islands is dependent on the oxygen pressure during growth and relates to the coordination number of the Mg cations.