Both time-resolved 2-photon photo-electron spectroscopy and scanning tunnelling microscopy were utilized for investigating the role of C-defects in the electronic property and dynamics of the p-type Si(001)(2x1) surface. It was found that the C-defect caused Fermi-level pinning when its density was more than 0.05 monolayer. The change in the inverse of the product of the bulk-to-surface electron transition rate S and in the extinction lifetime of the surface excited electron was examined as a function of the C-defect density, and it was found that the change doubled when the C-defect density increased from 0 to 0.1 monolayer on the surface. This indicated that the C-defect played an important (but limited) role in the surface carrier dynamics of Si(001).

Electronic Properties and Electron Dynamics of the Si(001)(2×1) Surface with C-Defects. S.Tanaka, K.Tanimura: Physical Review B, 2008, 77[19], 195323 (8pp)