Adatom-induced donor states during the early stages of Schottky-barrier formation: Ga, In, and Pb on Si(113)

We performed angle-resolved ultraviolet and soft-x-ray photoelectron spectroscopy for the early stages of Schottky-barrier formation of Ga, In, and Pb on Si(113) at room temperature. In the coverage region below 0.1 monolayer a band-bending behavior, typical for donor states, is found. The energies of the adatom-induced donor states in the band gap depend on the adatoms. The Schottky barrier reaches its final value at a coverage of about one monolayer. The values are 0.35 eV above the valence-band maximum for In and Ga and 0.425 eV for Pb. Measurements with Xe interlayers were made to verify that these interfaces are not reactive.