Electron spectroscopy and scanning tunneling microscopy study of quasi-two-dimensional freezing at the liquid/vapor interface of Ga-Bi alloys.
We have studied the interfacial characteristics of Ga-rich liquid Ga-Bi alloys at various compositions and temperatures up to 300 degrees C by different electron spectroscopies under ultrahigh vacuum conditions. In particular, the thickness and thickness profiles of Bi-rich wetting and surface freezing films have been measured. It is found that at the surface freezing transition the Bi film thickness jumps from approximately 5 A to macroscopic values of over 100 A. This distinct behavior is discussed in comparison with the results in Ga-Pb. In addition, we report first scanning tunneling microscopy observations of the surface structure of a solidified Ga(0.989)Bi(0.011) alloy after passing a surface freezing transition. The topology at room temperature is characterized by extended, atomically flat Bi terraces covered by nanosized triangular two-dimensional Bi islands.
Issanin
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Institute of Physical Chemistry, University of Karlsruhe (TH), Kaiserstrasse 12, D-76128 Karlsruhe, Germany.
Turchanin
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Freyland
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