ELECTRONIC-STRUCTURE OF SI(113)2X2-CS SURFACE STUDIED BY ARUPS

The electronic structure of a Si(113)2 x 2-Cs surface has been investi gated by low energy electron diffraction (LEED) and angle-resolved ult raviolet photoelectron spectroscopy (ARUPS). The surface-band dispersi ons were measured along the symmetry axes, Gamma-U[33(2) over bar] and Gamma-W[1(1) over bar0$], in the surface Brillouin zone. Three surfac e states were observed at the binding energy of 0.7 (A(1)), 0.95 (A(2) ). and 1.65 eV (A(3)) below the Fermi level at Gamma with overall disp ersions of about 0.15, 0.5, and 0.2 eV, respectively. The A(2) and A(3 ) states revealed a 2 x 2 periodicity along the [33(2) over bar] direc tion. Considering the alkali-metal adsorptions on low-index Si surface s and measured Cs 3d/Si 2p XPS peak intensity ratios, the Cs-saturatio n coverage of the 2 x 2-Cs surface was assigned to about 6/8 monolayer . Based on the Cs-saturated adatom + tetramer model, the A(1) and A(2) states are identified as Cs-induced adatom and tetramer states, respe ctively. The A(3) State has a surface resonance-like character. (C) 19 98 Elsevier Science B.V.