EXPERIMENTAL BAND-STRUCTURE AND FERMI-SURFACE OF A 2-DIMENSIONAL ER SILICIDE ON SI(111)

High resolution angle resolved photoemission measurements on a monolayer of Er deposited on Si(111) and annealed at 400-degrees-C are presented. A series of two-dimensional energy bands attests to the formation of a surface silicide with a high degree of perfection. In particular, a prominent band with remarkably large hole lifetimes (approximately 200 meV) and a dispersion of approximately 1.65 eV crosses the Fermi level near the GAMMA-BAR point of the surface Brillouin zone. The two-dimensional Fermi surface is typical of a semi-metal and consists of small hole and electron pockets about the GAMMA-BAR and MBAR points respectively.