Epitaxial (√3 × √3 )R30° ${\mathrm{ErSi}}_{1.7}$ films were grown on Si(111) by solid-phase epitaxy and examined in situ by ultrahigh-vacuum scanning tunneling microscopy (STM). Atomic resolution was achieved and the ${\mathrm{ErSi}}_{1.7}$(0001) surfaces were found to exhibit a high degree of structural order. Along with recent photoemission work, the analysis of high-resolution STM images shows that the surface atomic arrangement consists basically of a buckled Si layer without vacancies. An additional corrugation reflecting the √3 superstructure in bulk is superimposed on the p(1×1) structure.

• Received 13 December 1994

DOI:https://doi.org/10.1103/PhysRevB.51.10998