HIGH REACTION SELECTIVITY ON UV-LASER-INDUCED DESORPTION FROM CHLORINATED SI(111) 7X7 STUDIED BY SCANNING-TUNNELING-MICROSCOPY

Chlorinated Si(111) 7 x 7 surfaces were examined with scanning tunnell ing microscope images after pulsed laser irradiation at 266 and 355 nm with low laser fluence, where the thermal effect can be ignored. From the surface irradiated by the 266 nm laser, dichloride and trichlorid e species are desorbed, while monochloride species remain on the surfa ce. This desorption selectivity was not observed at 355 nm. These resu lts give useful information to elucidate the formation mechanism of a stripe pattern observed after 266 nm laser irradiation on a Cl-saturat ed Si(111) 7 x 7 surface.