AN ANGLE-RESOLVED PHOTOELECTRON-SPECTROSCOPY STUDY OF THE ELECTRONIC-STRUCTURES OF SI(001)2X2-AL AND SI(001)2X2-IN SURFACES

Angle-resolved photoelectron spectroscopy (ARPES) using synchrotron ra diation was employed to study the electronic structure of single-domai n Si(001)2x2-Al and -In surfaces. Five different dispersing surface st ate bands, denoted as S-1, S-2, S'(2), S-3 and S'(3), are identified w ithin bulk band gap with similar dispersions for both surfaces. From t heir dispersions and symmetry properties, the lowest-E(B) state S-1 is assigned as the surface state due to the dimer bond within the Al (In ) dimer and S-2, S'(2), S-3 and S'(3) due to the back bonds between Al (In) and top-most Si atoms. This result also gives a corroborating ev idence for the parallel dimer model of the surface structure.