EPITAXIAL-GROWTH OF AG DEPOSITED ON AIR-CLEAVED MGO(100) SURFACE BY MOLECULAR-BEAM DEPOSITION

The growth of Ag prepared by a molecular beam deposition method on air-cleaved MgO(100) surfaces with heat treatment at 1000-degrees-C for 30 min and without heat treatment has been studied using transmission electron microscopy, low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). In most cases, Ag crystals grow epitaxially on air-cleaved MgO(100) surfaces without heat treatment in a wide range of substrate temperatures. The heat treatment of air-cleaved MgO(100) is effective in promoting Ag epitaxial growth. The epitaxial temperature of Ag crystals on MgO(100) surfaces with heat treatment can be lowered to the room temperature. At room temperature, Ag films grow in Frank-Van der Merwe growth mode, while above 100-degrees-C, Ag crystals develop in Volmer-Weber growth mode. It is inferred from the present studies that segregated Fe3+ and Ca2+ impurities from the MgO bulk at high temperatures play a dominant role as nucleation sites of Ag.