التفاصيل البيبلوغرافية
| العنوان: |
Growth of Co clusters on thin films Al2O3/NiAl(100). |
| المؤلفون: |
Luo, M. F., Chiang, C. I., Shiu, H. W., Sartale, S. D., Wang, T. Y., Chen, P. L., Kuo, C. C. |
| المصدر: |
Journal of Chemical Physics; 4/28/2006, Vol. 124 Issue 16, p164709, 6p, 5 Color Photographs, 2 Graphs |
| مصطلحات موضوعية: |
THIN films, SCANNING tunneling microscopy, VAPOR-plating, COBALT, ATOMS, DYNAMICS |
| مستخلص: |
We present a scanning tunnel microscopy study of Co clusters grown through vapor deposition on Al2O3 thin films over NiAl(100) at different coverages and temperatures. Formation of Co clusters was observed at 90, 300, 450, and 570 K. At the three lower temperatures, we find narrow cluster size distributions and the mean sizes (with a diameter of 2.6 nm and a height of 0.7 nm) do not change significantly with the coverage and temperature, until the clusters start to coalesce. Even on 3–4-nm-wide crystalline Al2O3 strips where the deposited Co atoms are confined, the same features sustain. Only at 570 K the normal growth mode where the cluster size increases with the deposition coverage is observed, although the data are less conclusive. A simple modeling of kinetic surface processes on a strip confirms the normal growth mode, but fails to show a favored size unless additional energetic constraints are applied on the cluster sizes. Increasing Co coverages to cluster coalescence, a larger preferable size (mean diameter of 3.5 nm and height of 1.4 nm) appears for growth at 450 K. These two sizes are corroborated by morphology evolution of high Co coverages deposited at 300 K and annealed to 750 K, in which the coalescence is eliminated and the two preferable geometries appear and coexist. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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