The thickness-dependent electronic structures of Dy silicide films grown on a Si(1 1 1) surface have been investigated by angle-resolved photoelectron spectroscopy. Two (1 x 1) periodic bands, both of them cross the Fermi level, have been observed in the silicide films formed by Dy coverages of 1.0 monolayer and below, and more than five (root 3 x root 3) periodic bands have been observed in thicker films. Taking the (2 root 3 x 2 root 3) periodic structure of Dy atoms in the submonolayer silicide film into account, the periodicity of the two metallic bands indicate that they mainly originate from the orbitals of Si atoms, which form a (1 x 1) structure. Of the (root 3 x root 3) periodic bands observed in thick films, four of them are well explained by the folding of the (1 x 1) bands into a (root 3 x root 3) periodicity. Regarding the other band, the three (root 3 x root 3) periodic bands would originate from the electronic states related to the inner Si layers that form a (root 3 x root 3) structure, and the one observed in the 3.0 ML film only might originate from the electron located at the interface between bulk Si and the Dy silicide film. (C) 2009 Elsevier B. V. All rights reserved.