Effect of oxygen on the stability of Ag islands on Si(111)-7 × 7 |
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Authors: | Dahai Shao Xiaojie Liu Ning Lu C-Z Wang Kai-Ming Ho MC Tringides PA Thiel |
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Institution: | 1. Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA;2. Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA;3. Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA;4. Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, USA |
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Abstract: | We have used scanning tunneling microscopy to probe the effect of oxygen exposure on an ensemble of Ag islands separated by a Ag wetting layer on Si(111)-7 × 7. Starting from a distribution dominated by islands that are 1 layer high (measured with respect to the wetting layer), coarsening in ultrahigh vacuum at room temperature leads to growth of 2-layer islands at the expense of 1-layer islands, which is expected. If the sample is exposed to oxygen, 3-layer islands are favored, which is unexpected. There is no evidence for oxygen adsorption on top of Ag islands, but there is clear evidence for adsorption in the wetting layer. Several possible explanations are considered. |
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