Resistance vs time for a typical adsorption sequence for 0.095 ML sulfur precoverage, showing the initial sulfur dose and three subsequent oxygen doses. An Auger spectrum was measured after each dose. The interval between doses was approximately .
Surface resistance change vs oxygen coverage on a Cu(100) film with different sulfur precoverages at . The solid lines are the best-fit resistance-coverage curves obtained from the simulation described in the text. Compared to the linear coverage dependence without preadsorbed sulfur, interactions of S and O completely suppress the increase of surface resistance at high oxygen coverage until it levels off at a nearly constant maximum value.
Sample simulated adsorbate distributions for three different oxygen coverages and the corresponding changes in surface resistance with oxygen coverage for 0.095 ML sulfur coverage . Only a section of the full array is shown. (a) At low coverage, oxygen adsorbs far from the sulfur atoms, outside the effective range of suppression. The resistance change is not affected by sulfur. (b) With increasing oxygen coverage, O atoms occupy second-nearest-neighbor sites. The increase in resistance is slightly suppressed. (c) O atoms occupy first-nearest-neighbor sites. The resistance no longer increases with increasing oxygen coverage.
The simulated resistance change vs oxygen coverage for different values of the adsorption energy difference between first- and second-nearest-neighbor sites at 0.095 ML sulfur coverage . For significant deviations from the experimental data are observed.
Schematic depiction of the proposed interaction between partially occupied sulfur and oxygen orbitals that could result in the observed resistivity suppression.
Fitting parameters for the resistance contributions of the first- and second-nearest-neighbor sites, relative to the contribution of other sites without suppression. The three rows represent three different sulfur coverages.
Article metrics loading...
Full text loading...