Structural and Electronic Properties of Barium Silicide on Si(100)

Abstract

Barium silicides formed on the Si(100) surface have been investigated by scanning tunneling microscopy/spectroscopy (STM/STS). The structure of the silicide surface depends on the preparation procedure; three kinds of silicide phases coexist on the surface when 2 monolayers (MLs) of Ba are deposited on Si(100) at the specimen temperature of 850 K, while two of the three phases appear when 2 MLs of Ba are deposited on Si(100) at room temperature, followed by annealing at 850 K. The STS result indicates that all the phases show semiconducting behavior with a band gap of ∼ 1.3 eV and that one of the three phases has local density of states (LDOS) at 2.5 eV below the Fermi energy, which coincides with the reported results of metastable de-excitation spectroscopy (MDS) and ultraviolet photoelectron spectroscopy (UPS).