Water adsorption on an In/Si(111) surface: effect on the phase transition

초록

We investigated effects of water adsorption on the structural phase transition between the 4 x 1 phase and the 8 x 2 phase of an In/Si(111) surface using low-energy energy diffraction. We found that water molecules adsorbed on a 4 x 1 surface at room temperature decreased the transition temperature, by suppressing the condensation of the 8 x 2 phase. This role of water adsorbate contrasts to the previous observation that the adsorbate on the aged surface at 20 K enhanced the formation of the 8 x 2 phase. On the other hand, the adsorption of water on the 8 x 2 surface at low temperature caused disorder on surface but did not revert the 8 x 2 phase to the 4 x 1 phase. This result differs from the case of In impurities that also suppress the 4 x 1 -> 8 x 2 transition upon adsorption on the 4 x 1 phase and even revert the 8 x 2 to the 4 x 1 upon adsorption on the 8 x 2 phase.

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