Core-level photoemission study of 2D ordered Bi/Si(100) interfaces

A high resolution core-level photoemission investigation of 2D ordered Bi layers grown on Si(100)-(2×1) is presented. We study the Si 2p and Bi 5d core-levels at room temperature as a function of coverage and in the reconstructed phases. The different Bi structural configurations around the monolayer coverage and in the (2×n)- reconstructed phase are derived from the core-level lineshape evolution. By following the Fermi level pinning, the presence of Bi-induced occupied electronic states close to the Si mid-gap is suggested.