COMPARISON OF THE INITIAL OXIDATION OF POLYCRYSTALLINE INDIUM AND ULTRATHIN DEPOSITS OF INDIUM ON THE AU(111) SURFACE

Previous studies have shown that alloying occurs when indium deposits equivalent to a few monolayers are evaporated onto Au (111). This arti cle compares the initial oxidation of the ultrathin alloy to that of p olycrystalline bulk indium. Auger electron spectroscopy, electron ener gy loss spectroscopy, low energy electron diffraction, and work-functi on change measurements were conducted under ultrahigh vacuum condition s at room temperature. Oxidation of the polycrystalline sample follows first-order Langmuir kinetics, and saturates by 1 X 10(3) L (1 L = 10 (-6) Torr s), to form a 4.5 Angstrom thick oxide layer. The stoichiome try of the compound is In2O3. The oxygen uptake of the alloy saturates with less than two layers of In-Au alloy present, and an oxide layer of different stoichiometry is generated, 4.2 Angstrom thick. It is sug gested that gold may be participating in the alloy stoichiometry. The results are compared to another study of oxidation of bulk indium. (C) 1998 American Vacuum Society.