Laser-induced mono-atomic-layer etching on Cl-adsorbed Si 111/ surfaces

We have studied ultraviolet laser-induced monolayer etching process on Cl-adsorbed Si 111.-7=7 surfaces with X-ray photoemission spectroscopy. We keep the fluence as low as 1 mJrcm2 to discuss electronic excitation and relaxation at the surface during this process. After irradiation, silicon di- and tri-chloride species on the surface disappear and monochlorides remain at the surfaces. We conclude that surface adatom polychlorides and rest-atom polychlorides are desorbed primarily as SiCl2 species, and that adatom monochlorides and rest-atom monochlorides are stable against irradiation. Photo-excited electrons andror holes in bulk induces the SiCl2 desorption at the surfaces. q1998 Elsevier Science B.V. All rights reserved.