Initial stages of ${\mathrm{ErSi}}_{1.7}$ formation on Si(111) surfaces were investigated by means of low-energy electron diffraction, angle-resolved ultraviolet photoemission spectroscopy, and x-ray-photoelectron forward-scattering techniques. Experimental data are presented that demonstrate the formation of a p(1×1) ordered-surface silicide by deposition of one Er monolayer onto Si(111) held at room temperature and subsequently annealed at 550 °C. The structure of this two-dimensional compound appears to be similar to a single ${\mathrm{ErSi}}_2$ layer (${\mathrm{AlB}}_2$ structure) with a reconstructed Si top layer.

• Received 12 November 1991

DOI:https://doi.org/10.1103/PhysRevB.45.8490