Rare-Earth Silicides Surface and Interface Structure

3 Rare-Earth Silicides Surface and Interface Structure 

The RE-silicon interface is reactive, with formation of a RE-rich silicide. Annealing facilitates the ordering and formation of an epitaxial Si-rich silicide layer. In the case of epitaxial phases on Si(lll), a s/i x V3)R30 superstructure is frequently observed, which is attributed to the ordering of Si vacancies in the bulk. The top layer of the silicide is a buckled layer of Si atoms similar to the Si(lll)-(1 x 1) surface, as identified for YSij 7 [92]. Similar (VI x V3)R30 superstructures have been observed for several other trivalent RE silicides [93-96]. 

A single-layer silicide is formed after deposition of 1 ML of RE and annealing. 

Medium-energy ion scattering (MEIS) has been also used to determine the atomic structure of two-dimensional RE sihcides on Si(lll) [lOOj. In the case of the Si(lll)-(1 x 1)-Er, the MEIS results agree with previous findings. Si(lll)-(1 X l)-Ho was found to exhibit a structure similar to the Er 2D silicide. 

The same technique has been used to investigate the surface structures of the two-dimensional RE silicides formed by Gd and Tm on Si(lll), and the findings 

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