Angle-resolved photoemission study of electronic structure development during Ag growth on the Si(001) surface

Abstract

Angle-resolved photoelectron spectroscopy (ARPES) study of the initial Ag growth on the Si(001)2×1 surface has been performed using synchrotron radiation for Ag coverage up to 7.5 monolayer (ML) at room temperature. The evolution of Ag 4d and near-Fermi level valence band structures is investigated, which is interpreted consistently with the Stranski–Krastanov growth of Ag with an intermediate layer of roughly 1 ML. The ARPES spectra of the two-dimensional intermediate layer, the Si(001)2×1–Ag surface, are measured in more detail. This reveals three intrinsic surface-state bands and indicates the semiconducting nature of the intermediate layer. Two of these surface states at binding energies of ∼0.9 and ∼1.8 eV exhibit a close resemblance to the surface states of alkali-covered Si(001)2×1 surfaces. Based on these results the nature of bonding between Ag and Si for the initial adsorption is discussed.