INTERACTION OF OXYGEN WITH THIN COBALT FILMS

The interaction of oxygen with thin cobalt films supported on oxidized Si(100) substrates was studied using Auger electron spectroscopy (AES ) and work function changes (Delta phi) at 130 and 300 K. Oxygen uptak e curves were derived from the ratio changes of the O-KLL and Co-LMM A nger signals at 513 and 778 eV, respectively. They showed a constant s ticking coefficient (s(o)) up to approximate to 15 langmuirs, especial ly at 130 K, possibly indicating adsorption through a molecular precur sor that diffuses over the chemisorbed layer. At 300 K, s(o) = 0.2, wh ile at 130 K, 0.5 greater than or equal to s(o) greater than or equal to 0.3, depending on the dosing pressure. Up to approximate to 10 lang muirs O-2 at 300 K, the work function increased 0.20 eV. At that cover age, the Co MVV Auger transitions indicated an oxide formation. From t his coverage onward, the work function decreased, saturating at approx imate to 80 langmuirs with a value approximate to-1.2 eV below the cle an Co surface, pointing to oxygen diffusion into the bulk.